AutoForm Hydro

iletisim: [email protected]

ALGHAFORM PAYLASIMIDIR iletisim: [email protected] www.forum.alghaform.com

6 AutoForm–Hydro

AutoForm–Hydro is an AutoForm Software package for simulation of tube hydroforming processes – processes that use internal fluid pressure, acting in conjunction with the movement of axial and radial tools, to form and shape tubular blanks. In simulations using AutoForm–Hydro, load application through the fluid medium may be specified by pressure–, volume– and height–control. In the first variant, pressure–control, evolution of pressure during the forming process is specified by the user, and the resulting volumetric change is computed during the analysis. In the second case, volume–control, the desired change of volume is specified and the required pressure is calculated. The third variant, height–control, allows the user to define the approximate radial expansion of the tube during the deformation process. The resulting volumetric change and the required pressure are then calculated during the analysis. Volume– and height–control may be used in the early stages of process design, when pressure history and optimal tool kinematics are as yet unknown. Pressure–control should be used if the user already has a reasonable idea of its evolution during the deformation process (experience, similar processes, similar parts, etc.). The following tube deformation process components may be simulated using AutoForm–Hydro: • • • •

Prebending Annealing Preforming (closing of tools without fluid medium) Hydroforming (Forming with fluid medium)

In the current version, version 3.1, prebending is simulated in a single time step. This is a stable and efficient way to simulate prebending whereby changes in thickness and material hardening arising from prebending may be computed. However, change in cross sectional shape during prebending cannot be established using this single–step approach. www.forum.alghaform.com

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If shape of the tube cross section is important to simulate accurately subsequent forming stages (for example, if the prebent tube does not have the right shape in its cross section, it may not be possible to position it in the hydroforming tools), prebending may be simulated using the preforming process step. CAD models of the prebending tools – components of the complete tool that define the bent shape of the tube – are required in this case. The current version does not allow the simulation of rotary prebending operations. One of the most important features of AutoForm–Hydro is its user– friendliness and the ease with which simulations may be set up, run and evaluated. As with all other AutoForm Software packages, preprocessing and data input are tailored to the logical needs of the different simulation types. Such a user–friendly design of the software allows even the casual/occasional user to set up and run simulations and to thus carry out feasibility assessments reliably, easily and quickly. This chapter illustrates the application as well as features of the AutoForm–Hydro software package based on a series of tutorial lessons. Each lesson introduces new software features and highlights some of the wide variety of application possibilities. It is recommended that the user work through the lessons in the order listed here as this order represents a progression in the complexity of usage and features, and since each lesson assumes familiarity with features illustrated in the previous ones. In particular, Lesson 1 gives a very detailed description of the steps involved in the preparation and set up of a typical AutoForm– Hydro simulation, and is ideal for introducing the new user to the software. Special applications are described in detail in subsequent lessons where some familiarity with the software is assumed.

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Contents of the Workshop „AutoForm–Hydro“ Lesson 1

Set up of a Simulation with Linear Pressure History. History. . . . . . . . . . 4 • • • • • • •

Lesson 2

Specification of Axial Tools and their Movement . . . . . . . . . . 48 • • • • •

Lesson 3

Creating a new simulation file Importing CAD–geometry Specifying upper– and lower–tools Defining initial tube geometry Setting up process steps Starting the simulation Post processing results of the simulation

Opening an existing simulation file Inserting new tools (axial tools) Modifying the process step hydroforming Starting the simulation Post processing results of the simulation

Definition of Time–dependent Pressure– and Tool–Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 • Specifying an annealing process step • Defining fluid pressure versus time • Defining tool movement as a function of time

Lesson 4

Simulation of Hydroforming using a Counterpunch . . . . . . . . 71 • • • •

Defining geometry of a counterpunch Specifying working direction for counterpunch Specifying fluid pressure versus time Specifying movements (distance versus time) of counterpunch and axial tools


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Lesson 1: Set up of a Simulation with Linear Pressure History

6. 1 Lesson 1: Set up of a Simulation with Linear Pressure History As a first step in setting up, running and evaluating an AutoForm–Hydro simulation, it is necessary to open a new simulation file and to name it appropriately. This simulation file provides the right context, within the AutoForm–User Interface, for importing required data – CAD geometries, lines, material data, etc. – and for setting up a simulation as desired. In the present lesson, tool geometries will be defined on the basis of imported CAD geometries, the initial tube will be defined from its centerline and diameter, and a process sequence (comprising prebending, closing and hydroforming steps) will be established, with linear pressure evolution during hydroforming. Following these steps, the simulation may be started up, and simulation results may be evaluated/post processed. Fig. 1.1

Part geometry lesson 1

Import of a CAD–geometry

Starting up the AutoForm User–Interface The AutoForm–User Interface may be started up either by double– clicking on the pre–defined AutoForm icon on the user’s desktop, or by using the command xaf at the prompt of an open UNIX shell window. The User Interface displays the AutoForm Logo upon start up.


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Lesson 1: Set up of a Simulation with Linear Pressure History Fig. 1.2

AutoForm–User Interface Creating a new simulation file User interface

File > New ... > New file > File name: hy_lesson_01 > OK

Fig. 1.3

Dialog box: New file • File name: Enter name of *.sim file (without extension) • Units: Select units to be used for inputs. Length units should be the same as used in the CAD system. www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History • Geometric error tolerance: Enter value of acceptable chordal deviation error, to be used for meshing (see below). Default value is adapted to the length units selected under Units. Typical values are between 0.05 and 0.1 mm. Note: Note An input field, in any of the AutoForm input utilities, that is highlighted in red indicates that user input is mandatory in the respective field. Upon appropriate user input, these fields turn white. Input fields containing software default parameter values are also displayed in white; the user may modify the parameter values in these fields as required. Importing CAD–geometry Clicking on the OK button after completing inputs in the New file dialog box starts up the Geometry generator – a utility for importing and preprocessing surface geometry. Fig. 1.4

Geometry generator: Prepare page


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Lesson 1: Set up of a Simulation with Linear Pressure History The surfaces representing tool geometry (CAD–model of the tool) need to be imported and used to define tools for the simulation. These surfaces may be imported either from an IGES– or from a VDAFS–format file. During the process of importing such files, the AutoForm–Automesher automatically converts (in the background) the analytical surface descriptions into a mesh, and displays the meshed geometry in the main display. The meshed geometry may be examined visually for problems such as untrimmed or overlapping surfaces, and/or gaps between surfaces. If such problems do exist, they need to be fixed in the CAD system, and the corrected tool geometry needs to be re–exported (in IGES– or VDAFS–format), and re–imported into the AutoForm–User Interface. Reading in and meshing the CAD–model Geometry generator

File > Import ... The dialog box Import geometry is displayed. Here the format of the geometry file has to be selected. For Lesson 1 the CAD data of the tools is available in IGES–format.

Fig. 1.5

Dialog: Import geometry Import geometry > Format: IGES > OK Upon clicking OK, a file browser dialog box (Select a file) opens up from where the user selects the file to be imported.


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Dialog: Select a file Select a file > Files: hy_lesson_01_tools.igs > OK Upon clicking the button OK a new dialog box – the AutoForm– Automesher interface – opens up. Fig. 1.7

Dialog box: AutoForm–Automesher interface


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Lesson 1: Set up of a Simulation with Linear Pressure History The quality of mesh created over the tool surfaces in the IGES–format file is controlled by the AutoForm–Automesher parameters listed in the interface. Parameters:

• Error tolerance: Determines the chordal deviation error for meshing. This value is taken from the New file input interface (default: 0.1; see Fig. 1.3), but may be modified here. If the imported surface geometry has small radii (2 mm or less), this value should be reduced to 0.05. • Max side length: Maximum element side length in flat areas.

Faces:

• Treat only: Only faces with specified numbers will be meshed. • Exclude: Faces with specified numbers will not be meshed.

Layers:

• Treat only: Only layers with specified numbers will be meshed. • Exclude: Layers with specified numbers will not be meshed. Program: afmesh_3.1 > OK Clicking the OK button starts up automatic mesh generation using the AutoForm–Automesher (afmesh_3.1). Mesh generation typically requires a few seconds. The progress of the mesh generation can be tracked in the output area of the AutoForm–Automesher interface. Following mesh generation, the meshed geometry is displayed in the main display. Note: Note Please refer to Lesson 2 and Lesson 4 of the workshop AutoForm–User Interface for detailed instructions on controlling the display of geometry in the main display of the AutoForm–User Interface. No further inputs or actions are required in the Geometry generator, and it may therefore be closed. All further inputs may be defined entirely from within the AutoForm–Input generator.

Geometry generator

File > Dismiss


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Lesson 1: Set up of a Simulation with Linear Pressure History

Working with the Input generator

Start of the input generator

User interface

Model > Input generator ... Upon making the above menu selection, a dialog box appears wherein the type of simulation set up (Incremental, OneStep or Hydro) needs to be selected and the sheet/tube thickness needs to be specified.

Fig. 1.8

Dialog box: Simulation type Selection of the type of simulation Simulation type > Simulation type: Hydro Upon selecting Hydro the dialog changes to the form: Fig. 1.9

Window: Simulation type Hydro www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History Choice of tube wall thickness Simulation type > Tube thickness: 1.2 > OK The Input generator utility (Fig 1.10) opens up. The Input generator is organized into 6 pages with their respective tabs titled as follows: Title, Tools, Tube, Lube, Process and Control. These titles indicate the type of input data to be specified in each page. Further, tab titles highlighted in red indicate that one or more user inputs are required in the corresponding page. Although explicit user input may not be required in pages titled in black, the user is advised to check the correctness of the default input values in these pages before starting a simulation: AutoForm only checks for the presence of parameters in these pages, but NOT for their correctness/appropriateness for the simulation being set up. It is recommended that the user traverse the pages from left to right completing the required definitions/inputs under each page. Fig. 1.10

Input generator: Title page www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History Input generator: Title Under Title, the user may include a brief description of the present simulation/product. The content of this box is displayed in the lower left corner of the main window and also appears as an annotation on a postscript printout/file output. Title

Title: hy_lesson_01 (training, date) Note: Note While a brief title – consisting of the simulation file name, username and current date – is automatically created, this may be edited and modified by the user. In addition to the Title field, the user may write in a description of the current level of development, material, etc. in the field titled Comments (Fig. 1.10). Input generator: Tools Two types of tools may be specified for an AutoForm–Hydro simulation: Lateral and Axial. • Lateral: Lateral tools work/move “laterally” to the tube. For example upper– and lower–die, all preforming tools, sliders, counterpressure punch (radial punch) etc. • Axial: Axial tools work/move „axially“ to the tube. Axial punches/counterpunches – that are used to facilitate targeted material flow in the forming zone – may be defined using this option. Only two axial tools can be defined. Axial start at the beginning of the tube and Axial end at the end of the tube. A page needs to be created under the Tools page for each tool in the simulation. One such page, for the lateral tool (die), is already defined (Fig. 1.11). Tool pages for additional tools need to be created by the user. In Lesson 1 two lateral tools (upper– and lower– die) have to be defined. Definition and usage of axial tools will be described in Lesson 2.


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Input generator: Tools page First the predefined tool die needs to be renamed as upper_die. This is accomplished very easily by clicking the mouse pointer in the input field Name (Fig. 1.11) and typing in the new name. Tools

die > Tool name > Name: upper_die > Enter The subpage die is thus renamed as upper_die. Tool geometry must now be defined. This may be carried out by using one of two options: Reference ... and Read f. file ... (Fig 1.11). • Reference: Based on the tool geometry entities already imported (Geometry generator). Currently active meshed faces of the selected imported entity may be assigned to the tool.


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Lesson 1: Set up of a Simulation with Linear Pressure History • Read f. file: By reading in tool geometry previously saved to file in AutoForm–format (e.g. tool data from earlier simulations). Tools

upper_die > Geometry: Reference ... A new dialog box appears (Fig. 1.12) wherein faces may be selected that may then be defined as the tool geometry. The following are the available options for selecting faces:

Fig. 1.12

Window: Reference tool geometry • Current geometry: The valid geometry is displayed and all further actions refer to this geometry. If more than one geometry is available in the geometry generator the appropriate one may be selected here. • Pick faces: In the current version of AutoForm–Hydro, Pick faces is the only available method for identifying geometry (tool surfaces) for subsequent definition. • Activate/Deactivate: Faces may be picked or highlighted using the right–mouse button (or Shift – right mouse button). Once picked, these faces may be activated or deactivated using the Activate/Deactivate button. If a picked face is already active, it may only deactivated. Conversely, an active face may only be deactivated. Also, it is only possible either to activate or to deactivate a face at a time: it is not possible to activate a few of the picked faces and to simultaneously deactivate others. • Activate all: The button Activate all activates all faces. This option is used to activate the whole model. • Toggle active: The button Toggle active inverts the activation status of the objects in the geometry file: it activates www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History the deactivated objects and deactivates those that are activated. The faces of the tool upper_die are selected as follows: To select a face that will be part of the tool to be defined, click on the desired face with the right mouse button Note: Note Several faces can be selected using the Shift – right mouse button combination. This key combination may also be used to create a rectangular “rubber band” which may be used to enclose a set of faces to be selected. Two selection possibilities are available: Only those faces that lie entirely within the rubber band may be selected, or those faces that are entirely within the rubber band and those that intersect the rubber band may be selected. It is possible to toggle between these options as follows: File > Preferences > Select crossing (on or off). Select the faces which represent the tool to be defined, and activate them, as shown in Fig. 1.13. Fig. 1.13

Necessary faces for the tool upper_die Complete the definition of tool geometry, after picking the appropriate faces, by clicking on OK in the Reference tool geometry dialog box. Reference tool geometry > Activate > OK www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History No further inputs are required in this subpage of the Tools page. However a short description of Position and Offset is given here: • Position: Positioning is used to move the tools into correct position prior to start of the simulation. The input fields correspond to the x–, y– and z–coordinate. • Offset: An input for the offset means that from the new tool an offset is created with the value in this field. Usually it is not necessary to specify any offset for hydroforming. In the field Working direction the working direction for each tool is defined: • dx dy dz: A vector in x–, y– and z–direction determines the working direction for the tool. • Move: Movement of the tools in or opposite to working direction is defined here. Tools

upper_die > Working direction > dx dy dz: 0, 0, –1 > Move: -10 Note: Note The input for Move must be –10 because the tool is moved against the working direction. It is also possible to define the working direction by a start/end point or by a default curve/line. Tool stiffness is specified in the Stiffness input field. A stiffness value of approximately 50 is appropriate and should not be changed. When complete, the upper_die tool input page appears as shown in Fig. 1.14.


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Inputs for the tool upper_die in the page Tools It is necessary to define another tool (lower_die) for the simulation. To do this, a new subpage has to be created under the Tools page. Tools Fig. 1.15

Add tool ... The Add tool (Fig. 1.15) dialog box opens up.

Dialog box: Add tool www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History • Type of tool: The type of the tool (Lateral or Axial, see above) is defined here. • Default tool settings: Input values, except geometry, of an earlier defined tool can be taken over (Use settings of tool:), or the standard settings (Use default settings) can be selected. Note: Axial start or Axial end end) only standard settings Note For axial tools (Axial are available. Selection of type and settings for the new tool Tools

Add tool > Type of tool > Lateral > Use settings of tool: upper_die > Add tool A new Tools page opens up, with the settings carried over from the tool page upper_die. For this new tool the name, the geometry and the working direction must be defined. The procedure to do so is same as described above. Settings for the new tool

Tools

tool2 > Name: lower_die > Enter Geometry > Reference ... Select faces, from the geometry displayed in the main display, by using the Shift–right mouse button combination (Fig. 1.16), and activate the selected ones using the Activate button in the dialog box Reference tool geometry. Reference tool geometry > Activate > OK

Tools

lower_die > Working direction > dx dy dz: 0, 0, 1 Note: -10) Note Setting for Move (-10 -10 was taken over from tool upper_die automatically.


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Necessary faces for the tool lower_die After the inputs for the tool lower_die are completed, the subpage for this tool should appear as shown in Fig. 1.17.


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Inputs for the tool lower_die in the page Tools All specifications on the page Tools are thus complete for Lesson 1. Input generator: Tube All details relating to the tubular blank material are specified on this page (Fig. 1.18). Note: Note The designation tube includes all semi–finished material with any cross section drawn along a defined axis.


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Input generator: Tube page Three dimensional geometry of the tube axis needs to be specified first. If a pre–bent tube is used during hydroforming, the axis of this pre– bent tube needs to be defined here. This specification is essential even if prebending of the tube is to be simulated using Prebending as the first process step. Note: Note The pre–bent tube axis must be present as a curve. Bend information such as axis and radius of bend may not be used here. There are different ways to define the tube axis: • Input: Contour of tube axis is created using the Curve editor. • Import: The tube axis is specified directly by import from a CAD file. www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History • Copy from: The tube axis is specified as a copy of an existing curve. This curve can be selected from curves listed in the Curve manager. These curves may have been imported into the Curve manager from a CAD–file, or they may have been already generated in AutoForm. Note: Note After definition of the tube axis the button labeled Input changes to read Edit. Edit Now tube axis can be edited using the Curve editor. To specify the tube axis an existing curve from a CAD file is selected. Import of a tube axis Tube

Axis > Import ... The dialog box Import line(s) (Fig. 1.19) appears. Here the format of the file to be imported has to be selected. For Lesson 1, the CAD data of the tube axis has been saved in IGES–format

Fig. 1.19

Dialog box: Import line(s) Import line(s) > Format: IGES > OK The often–encountered dialog box – Select a file – opens up, and the IGES–file for the tube axis can be selected. Select a file > Files: > hy_lesson_01_axis.igs > OK Upon clicking the button OK the AutoForm–Automesher interface appears. No further inputs have to be specified, and the mesher afmesh_3.1 is started by clicking OK. Program: afmesh_3.1 > OK www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History After completion of meshing the dialog box Select curve (Fig. 1.20) appears. Here all meshed curves are listed, and the appropriate one may be selected for the definition of the tube axis. Fig. 1.20

Dialog: Select curve Select curve > Curve 1 > OK Note: Note It is also possible to select one or more curves in the main display with the right mouse button. Tube cross section needs to be specified next. Similar to the definition of tube axis, there are several input modes to specify tube cross section. Additionally circular cross section may be defined using the button Circle. Here the outer diameter may be specified. (Fig. 1.21). Fig. 1.21

Dialog: Cross section - Circle Tube

Cross section > Circle ... > Cross section - Circle > Outer diameter: 58 > OK Note: Note Always the so–called neutral fiber has to be defined for the cross section, except the definition of the cross section by Circle. Circle In this case the outer diameter will be automatically converted to the neutral fiber. www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History It is possible to influence the position of the cross section relative to the tube axis. This can be done using the field Cross section: • Axis pos: Input boxes may be used to specify the position of the tube axis relative to the center of the cross section defined. If these boxes are empty, or if both boxes have the value 0, the tube axis is positioned to pass through the center of the cross section. If a x– and/or y–value is input, the tube axis is positioned accordingly with respect to the center of the cross section of the tube. • Ref X: This option is useful only if the cross section is noncircular. The cross section can be rotated around the tube axis by the specification of a vector. For Lesson 1, it is not necessary to define either Axis pos, or Ref X.. Here it is possible to move the position of the tube in x–, y– and/or z–direction. In the field Properties, material properties of the tube must be specified. • Thickness: Thickness of the tube wall. Although this value is specified when starting up the Input generator, it may be modified here. • Material: The user may select an appropriate pre–existing material data file from the available material database (Import), or set up the material data by specifying all of the required material properties (Input). Either way, the specified material characteristics may be reviewed by clicking on the View button. • Rolling direction: Here the rolling direction of the tube needs to be specified. The rolling direction may be either Axial or Circumferential. Definition of thickness and the material of the tube Properties > Thickness: 1.2 > Material: FeP04_1 > Rolling direction: Axial

Tube

After the inputs for the tube are finished the page tube should appear as shown in Fig. 1.22.


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Inputs for the tube on the Tube page Input generator: Lube On this page a coefficient of friction for all defined tools is specified (Fig. 1.23): • Constant: Friction is specified with a constant coefficient for all defined tools. It is possible to select pre–defined values with the buttons Special lubrication, Standard and Clean. If User defined is selected, an input is necessary. • Table: It is possible to define different coefficients of friction for each tool. Note: Note Pre–defined/default values may be modified in the file AutoForm.cfg, located in the AutoForm software installation directory.


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Input generator: Lube page Definition of the coefficient of friction Lube

Lubrication > Constant > Constant: User defined: 0.1 The completed Lube page should appear as shown in Fig. 1.23. Input generator: Process The process step hydroforming is pre–defined on the page Process as standard.


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Input generator: Process page For the present simulation, additional process steps must be defined. Therefore it is necessary to add process subpages under the page Process. Process

Add process step ... The dialog Add process step appears (Fig. 1.25)


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Dialog: Add process step There are three different types of process steps in AutoForm– Hydro: • Prebending: This type is used to simulate prebending processes. • Forming: All forming processes, except the prebending, may be simulated using this type of process. • Annealing: Using this type, an annealing process step may be defined. Note: Note The appearance of a new process subpage depends upon the type of process selected to be specified. In some cases, no user inputs are required beyond selection of that process type. Selection of process step Prebending Add process step > Type of process step: Prebending The dialog Add process step changes its appearance (Fig. 1.26)


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Dialog: Add process step, step Type: Prebending Further inputs cannot be specified in this dialog. Preforming may be simulated only as the first step and can only be defined once at the beginning of a simulation. With Add process step a new process step subpage will be added under the page Process. The name of this new process step may be changed; also, it is possible to define if the start (Start locked) or the end (End locked) of the tube should be locked when simulating prebending. Note: Note Prebending of the tube is simulated in this process step in a single increment. This process step allows the computation of thickness and hardening distribution only, and not changes in the tube cross section. For Lesson 1 predefined/default inputs are used. The page for the Prebending should now appear as shown in Fig. 1.27.


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Inputs for Prebending on the Process page A new process step has to be defined for closing the tools. Add process step ... > Add process step > Type of process step: Forming

Process

Dialog Add process step looks as shown in Fig. 1.28.


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Dialog box: Add process step, step Type: Forming For this type of process step it is possible to specify further inputs in the dialog Add process step: • Forming step – default settings: The settings of a previously defined process step (Use settings of forming step:) may be taken over, or standard defaults (Use default settings) can be selected. • Insert position: In this field the position of the new process step is determined. One of the existing process steps has to be identified. After this, it is necessary to specify whether the new process step should be inserted before (Insert before) or inserted after (Insert after) the selected process step. Further inputs in the dialog box Add process step (see Fig. 1.28): Add process step > Use default settings > Insert before > hydroforming > Add process step A new subpage (hydroforming2) is added under the page Process. The following inputs need to be specified here: • Name: In this field the name of the process step must be entered. • Type: The process step Forming has the following subtypes:


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Lesson 1: Set up of a Simulation with Linear Pressure History • Preforming: Used to simulate preform operations (except for prebending) or the closing of the tools without fluid medium. This is the default for the process step Forming. • Hydroforming: The hydroforming process (forming with fluid medium) may also be defined here. There are different ways of specifying a hydroforming process step, as will be explained during the description of the process step Hydroforming. Note: Note The subpage changes its appearance depending on the type of the process step Forming selected. Inputs for the new process step hydroforming2 > Process step > Name: closing > Type: Preforming

Process

The subpage for this process step should look like shown below: Fig. 1.29

Inputs for the process step Forming on the page Process www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History Further specifications refers to the tool control and the defaults for time: • Tool Control: All defined tools are listed (in case not all tools are shown, the button Show all must be pressed in/ turned on). Three control mode possibilities are available for each tool. • Non-active: Tool is not used during this process step. • Stationary: Tool is active but stationary during this process step. • Displcmnt: Tool moves during this process step. A velocity needs to be specified for this tool. • Duration: Here the duration of the process step is specified. • Until time: The time – measured from start of simulation – until completion of this process step. • Until closure: Time needed to close two tools against one another is established automatically based on contact between these tools. • During time: The time – measured from start of this process step – until completion of this process step. Following inputs for tool– and time–control should be taken specified: Process

closing > Tool control > upper_die > Control mode: Displcmnt > Forming step - tool setup > Velocity: 1 > Set lower_die > Control mode: Displcmnt > Forming step - tool setup > Velocity: 1 > Set Duration > During time > Time: 10 Note: Note The duration of the process step depends on the distance of the tools and the selected velocity. With a distance of 20 mm between upper– and lower–die, and a specified velocity of 1 for both tools, the duration of movement of both tools towards one another is 10 s. The subpage for the process step closing should appear as shown in Fig. 1.30 upon completion of inputs.


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Inputs for closing under the page Process Hydroforming is defined as the last process step. When opening the input generator a process step hydroforming is already predefined, and must be modified for this lesson. The type of this forming process step is hydroforming (see above). This process type offers the following options to control of load (fluid pressure) evolution: • Pressure–control: The evolution of pressure is specified. • Volume–control: The desired change of volume is specified and the required pressure evolution is calculated during the simulation. • Height–control: The approximate radial expansion of the tube has to be defined. The required pressure evolution is calculated during the simulation.


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Lesson 1: Set up of a Simulation with Linear Pressure History Note: Note This process subpage’s appearance depends on the selected load control method. Inputs specific to the load control option chosen need to be provided. In this lesson hydroforming will be done using an increasing pressure during the process. This option (Hydroforming, Pressure) is predefined for the type Hydroforming. Further inputs for tool and pressure control as well as the specification of the time must be completed. Process

hydroforming > Tool control > Show all > upper_die > Control mode: Stationary > lower_die > Control mode: Stationary Inputs for the process of pressure must be specified in the field Hydroforming. Clicking on the button No pressure starts up the dialog box Pressure (Fig. 1.31).

Fig. 1.31

Dialog box: Pressure For pressure–controlled processes, there are two ways to define pressure: • End p: The end pressure has to be specified. • Time variable: The increase of pressure is defined as dependent on time. Note: Note Pressure inputs are made in N/mm². Options available in this dialog box depend on the particular pressure input mode chosen (End End p, variable), and may require additional inputs. p Time variable


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Lesson 1: Set up of a Simulation with Linear Pressure History In this lesson the end pressure (at end of process step) is specified. Use of the time variable pressure option is described in Lesson 3. Pressure > End p > Value: 70 > Set Time input also needs to be completed as follows: Process

hydroforming > Duration > During time > Time: 70 The subpage for the process step hydroforming should appear as shown in Fig. 1.32 upon completion of all above inputs.

Fig 1.32

Inputs for hydroforming on the page Process This completes the input of process parameters and description for this simulation. Inputs under the Control page are reviewed below.


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Lesson 1: Set up of a Simulation with Linear Pressure History Input generator: Control Fig. 1.33

Input generator: Control page Inputs on this page (Fig. 1.33) may be numerical (Main), or may be a selection of result variables (Rslts). Default settings may be used over for Lesson 1 except for the following changes. Control

Main > Restart/post output > WriteRestart (switch off) Rslts > Contact results > Contact distance above (switch on) All necessary inputs are now complete, and the simulation may be started, after savings the inputs. The simulation will be saved under the name that was entered in the dialog box New file. The Save as option may be used to save the www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History inputs to a file with a different name. The user may save the input data from time to time to avoid loss of data in the event of crash of the workstation, loss of power, etc. Input generator

File > Save Job > Start simulation/View log The window Start job appears (Fig. 1.34).

Fig. 1.34

Window: Start job Only one simulation may run at any time. Additional simulations may be set up and queued using the Queue option at the bottom of the Start job window. These additional simulations may be added either to the end or start of the current queue. The simulation can be started by clicking on the button Start. Start job > Program: afhydro_3.1 > Start Computed results are appended progressively to the input data – geometry, process parameters, control parameters – saved in the www.forum.alghaform.com

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Lesson 1: Set up of a Simulation with Linear Pressure History simulation file specified in the New file input box. Currently available simulation results may be viewed at any time after starting the simulation by reopening the simulation file (File > Reopen) in main display. After the entire simulation is completed, the window Start job should be closed using the Dismiss button.

Analysis of results In the following the analysis of the most important result variables will be discussed. Open the *.sim file after the solver finished the calculation. User interface

File > Reopen Go to the end of the computed simulation:

User interface

Time > hydroforming Note: Note This can also be achieved with the combination of keys Ctrl – E. There are different ways to display result variable: • Using icons: A subset of the computed results (Thickness, Thinning, ...) may be displayed by using corresponding icons displayed on the right side of the main window (Fig. 1.35). • Results menu: All selected result variable are listed under Result variables in the Results menu (Fig. 136).

Fig. 1.35

Icons for the result variables www.forum.alghaform.com

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Result variables pull–down menu Formability The result variable Formability displays the strain state at different locations on the formed tube/sheet (based on the Forming Limit Diagram – FLD), and gives the user an overall picture of formability. Different colors are used to denote the following qualitative types of strain states. • Cracks: Areas of cracks. These areas are above the Forming Limit Curve (FLC) of the material used. • Excess. Thinning: In these areas thinning is higher than the acceptable thinning level (default value for steel 30%). • Risk of cracks: These areas may crack. By default this area is within a 20% zone below the FLC. • Safe: All areas which have no defects – wrinkles, thinning or cracks. • Insuff. Stretching: Areas which do not have enough strain (default 2%). • Wrinkling tendency: Areas where wrinkles might appear. In these areas the material has compressive stress but no compressive strain. • Wrinkles: Areas where wrinkles can be expected, depending on geometry curvature, thickness and tool contact. Material in these areas has compressive strains.


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Lesson 1: Set up of a Simulation with Linear Pressure History Display of the result variable Formability User interface

Results > Result variables ... > Formability > Dismiss or Select icon Formability. Display of the result variable Formability in the main display (Fig. 1.37).

Fig. 1.37

Display of the result variable Formability in the main display In this example cracks can be expected on one side of the dome. On the opposite side, there exists the risk of cracks (Fig. 1.37). The default–values of result variable Formability can be changed in the following menu:


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Lesson 1: Set up of a Simulation with Linear Pressure History User interface

Results > Formability ...

Fig. 1.38

Dialog: AutoForm - Formability The small plot shows the different strain regions/states with respect to the FLC. Thinning Another result variable that is often used is the percentage thinning of the material (Thinning). Display of the result variable Thinning in the main display: Results > Result variables ... > Thinning > Dismiss

User interface

or Select icon Thinning.


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Lesson 1: Set up of a Simulation with Linear Pressure History Display of the result variable Thinning in the main display (Fig. 1.39). Fig. 1.39

Display of the result variable Thinning in the main display A scale is displayed in the lower part of the main window with a range of 30% thinning (-0.3) to 10% thickening (0.1) colored from yellow to green (depending on the use color settings). The exact thinning level at any location on the formed tube/sheet may be displayed by clicking at that location on the tube/sheet (in the main display) using the right mouse button. Esc removes the labels from the display. To find the maximum thinning and the maximum thickening of the part use the following options: User interface

Results > Show max Results > Show min


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Display of the result variable Thinning with min and max values in the main display Note: Note The labels for max and min cannot be removed with the key Esc. Esc They have to be switched off by using Results > Show max and Results > Show min as toggle switches. To analyze the areas with high values for thinning the range of the Thinning scale must be changed. Results > Ranges ...

User interface

The dialog AutoForm – Min/Max Editor appears.


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Dialog: AutoForm – Min/Max Editor Note: Note The AutoForm - Min/Max Editor may also be accessed from the Results menu in the user interface: Results > Result variables: Ranges. Ranges • Min/Max Simulation: Use min and max values of the whole simulation. • Min/Max Increment: Use min and max values of the current increment. • Simulation default: Use default min and max values. • Manual: Use user defined min and max values. Change the values for the scale manually: AutoForm – Min/Max Editor > Manual > Min.: -0.4 > Max.: -0.2 > Return > Dismiss Display should correspond to Fig. 1.42. All areas with less than 20% thinning are displayed in green (depending on the chosen color settings).


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Display of the result value Thinning with min value –0.4 and max value –0.2. –0.2 Contact distance above With this result variable the distance of each element to the surfaces of the tools is displayed. Thus it is possible to check if the tube is formed out at the end of the simulation, i.e. if it has contact to the tool everywhere. If this is not the case, the pressure must be increased or the radii have to be increased. Results > Result variables ... > Contact distance above > Dismiss

User interface

The range of the scale may be modified to obtain a more meaningful display: Results > Ranges ... > Manual > Min.: 0 > Max.: 1 > Return > Dismiss

User interface

The display should correspond to Fig. 1.43.


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Display of the result value Contact distance above with min value 0 and max value 1 You can see that the part is not formed out completely in the area of the dome, in particular at the radii in this region. Simulation predicts cracks in the area of the dome when using the load control method specified here. In Lesson 2, it will be attempted to prevent splitting by trying to push material into the forming zone.


47

Lesson 2: Specification of Axial Tools and their Movement

6. 2 Lesson 2: Specification of Axial Tools and their Movement Building on the simulation from Lesson 1, we show in this chapter how to improve the result (cracks within the area of the dome). For this, the existing simulation from Lesson 1 is read in. Since the formability within the area of the dome is exhausted and results in cracks, to after–push over tried directed material into the transformation zone. This is implemented by axial tools (– slide gate valves), which are to be defined as new tools. In the hydroforming process step, these redefined axial tools must be considered and the axial tool movement should be determined. During the following analysis we see that the results (among other things regarding the cracks) could be improved substantially (Fig. 2,1). Fig. 2.1

Calculated part lesson 2

Read in a simulation For this example, an existing simulation is used and modified as required. For this a prepared *.sim file is available, which is based on Lesson 1. File > Open

User interface

The dialog opens with Select a file (Fig. 2.2). www.forum.alghaform.com

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Lesson 2: Specification of Axial Tools and their Movement Fig. 2.2

Dialog: Select a file Select the following sim file in the dialog Select a file: Files: hy_lesson_02.sim > OK The geometry from Lesson 1 is shown in the main window and the input generator for a Hydro simulation is opened.


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Lesson 2: Specification of Axial Tools and their Movement Fig. 2.3

Geometry in the user interface Some modifications in the input generator must be made now.

Modifications in the Input generator

Input generator: Title The title for the new simulation can be modified. Title

Title: hy_lesson_02 (training, date) After this, you can continue to work on the Tools page. Input generator: Tools Here the axial tools must be defined, with which the material is to be moved directly into the transformation zone. As mentioned in Lesson 1, only an axial tool can used for the start of tubing, Axial start, and an axial tool at the tube end, Axial end has to be defined. Note: Note The axial tools are created automatically. It is not possible in the present version to define your own geometry for the axial tools.


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Lesson 2: Specification of Axial Tools and their Movement Create the axial punch: Tools

Add tool ... > Add tool > Axial start > Use default setting > Add tool A new tool was defined of the type Axial start. Now, the name must be modified: tool3 > Tool name > Name: axial_start > Enter Further specification are not required here. Note: Note The working direction is set to standard by default. This working direction is then the direction (curved) of the tubing axle. In addition, it is possible to define for the working direction a vector (dx dx dy dz dz). The second axial tool is similarly created:

Tools

Add tool ... > Add tool > Axial end > Use default setting > Add tool > tool4 > Tool name > Name: axial_end > Enter Thus, the axial tools are defined. Further specification must be only given now on the Process page. Input generator: Process On the Process page, only the process step hydroforming has to be redefined and must be selected. The redefined axial tools are set by default to Non active and must be all inserted with Show. First, the tool control for axial_start is defined:

Process

hydrofoming > Tool control > axial_start > Control mode: Displcmnt


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Lesson 2: Specification of Axial Tools and their Movement The dialog Forming step - tool setup appears, in which a constant rate (Constant velocity) or a shift in dependency of the time (Time variable displacement) for the axial tool can be selected for axial_start (Fig. 2.4). Fig. 2.4

Dialog: Forming Step – tool setup Note: Note In order to check for which axial end the tool attacks b, this tool can be displayed in the main window, by clicking on the button named axial_start on the bottom right in the main window. This applies similarly to all other tools. Define the velocity for the axial tool axial_start: Forming Step - tool setup > Constant velocity > Value: 0.01 > Set Note: Note Option Time variable displacement is explained in lesson 3. Thus the control inputs of the tool axial_start are completed. Now the specification for the tool axial_end will be defined: hydrofoming > Tool control > axial_end > Control mode: Displcmnt > Forming Step – tool setup > Constant velocity > Value: 0.1 > Set

Process

Thus the specification on the Process page is finished.


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Lesson 2: Specification of Axial Tools and their Movement The page for the process step hydroforming should look as in Fig. 2.5 now. Fig. 2.5

Specification for hydroforming on the Process page From the Control page, make sure the WriteRestart option is switched off and under Rslts the post variable Contact distance above is switched on Now the simulation can be started: Input generator

File > Save Job > Start simulation ... > Start job > Program: afhydro_3.1 > Start After the calculation is complete, the *.sim file is re–opened and the results can be analyzed. Close the Start job window with Dismiss.

User interface

File > Reopen Time > hydroforming www.forum.alghaform.com

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Lesson 2: Specification of Axial Tools and their Movement

Analysis of the simulation results

Formability First the simulation is examined with the Formability criterion. The post variable is activated by clicking the Formability button on the icons menu located on the right side of the main window (moving the mouse over each icon shows the label). It is clearly seen that the critical areas of the dome are now no longer at risk of splitting (Fig. 2.6). Fig. 2.6

Representation of the post variable Formability in the main display


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Lesson 2: Specification of Axial Tools and their Movement Thinning Now the second post variable Thinning will be analyzed. The Icon Thinning is selected. From the Thinning plot, it is clear that an improvement of the result has been achieved by the axial tool movement (Fig. 2.7). Fig. 2.7

Representation of the post variable Thinning in the main display Contact distance above The forming–out of the pipe can be checked with the Contact distance above result criteria: User interface

Results > Result variables ... > Contact distance above > Dismiss Results > Ranges ... > Manual > Min.: 0 > Max.: 1 > Return > Dismiss


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Lesson 2: Specification of Axial Tools and their Movement The representation in the main display should look as in Fig. 2.8: Fig. 2.8

Representation of the post variable Contact distance above in the main display It can be seen that the forming–out the pipe has been improved by the axial tool movement. The pipe is almost completely formed out. There are only certain small areas in the dome, which have a small distance of the pipe to the tool surface. Finally, the Forming Limit Diagram is to be analyzed. Forming Limit Diagram The Forming Limit Diagram (FLD) describes the failure of the sheet metal due to cracks. In the FLD the Forming Limit Curve (strain states above those failure/cracks are detected) is represented as a black curve. Into this diagram, all finite elements of a simulation with the two main strain results (major and minor) are shown. So one can judge the robustness of a reforming process also visually in this diagram.


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Lesson 2: Specification of Axial Tools and their Movement This diagram is activated with the following instruction in the main window: User interface

Results > FLD ... By selecting Show all (on the top right), all the elemental strains are shown in this diagram (Fig. 2.9). In the current example, all strains are situated below the border deformation curve. This indicates that the process is quite safe and robust from a formability standpoint.

Fig. 2.9

Representation of all finite elements in the forming limit diagram at the end of the forming process It is also possible to plot the colors of the post variable Formability in the forming limit diagram: AutoForm – FLD > Diagram > Formability


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Lesson 2: Specification of Axial Tools and their Movement The representation is then as in Fig. 2.10. Fig. 2.10

Representation of all finite elements in the forming limit diagram with the colors of the post variable Formability The window AutoForm - FLD is closed with Dismiss. The user interface can be closed as follows: File > Quit or hot keys Ctrl – Q

User interface


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control

6. 3 Lesson 3: Definition of Time–dependent Pressure– and Tool Control Tube hydroforming requires numerous process steps for manufacturing: The semi finished tube undergoes prebending, annealing and hydroforming with time–variable pressure increase and axial tool displacement. To achieve this in simulation, it is necessary to define lateral and axial tools first. Next, we need to specify prebending and annealing. Finally, it is necessary to add time–pressure–control and time variable tool movement. Fig 3.1

Part geometry Creating a new project File > New ... > New file > File name: hy_lesson_03 > OK Meshing and import of CAD geometry The CAD tool data for this example is provided in IGES – format. Geometry generator > File > Import ... > Import geometry > Format: IGES > OK > Select a file > Files: hy_lesson_03_tools.igs > OK This opens the meshing dialog: Program: afmesh_3.1 > OK

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Lesson 3: Definition of Time–dependent Pressure– and Tool Control After meshing, the full tool appears in the main display. Close the Geometry generator: Geometry generator > File > Dismiss Input generator data User interface

Model > Input generator > Simulation type > Hydro For this example please use an initial wall thickness of 1.2 mm. Simulation type > Tube thickness: 1.2 > OK Input generator: Title

Title

Title: hy_lesson_03 (training, date) Input generator: Tools In case the semi tube is not formed by tool closure, it is not necessary to define the above– and below tools. Only one (closed) tool is sufficient. Lesson 3 will contain one lateral tool only. Definition of a lateral tool:

Tools

Geometry > Reference ... In the main window, select all faces using the right mouse button (Fig. 3.2) and open the Reference tool geometry dialog using Activate. Reference tool geometry > Activate > OK


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Fig. 3.2

Faces for the lateral tool Fig. 3.3

Input for lateral moving tool on Tools page www.forum.alghaform.com

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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Please use the default settings for tool working direction and stiffness (Fig. 3.3). Definition of axial moving tools: Tools

Add tool … Add tool > Axial start > Use default setting > Add tool tool2 > Tool name > Name: axial_start > Enter Please use the default settings for tool working direction. The last remaining tool is axial_end. For this definition, follow the procedure described for tool axial_start accordingly.

Tools

Add tool … Add tool > Axial end > Use default setting > Add tool tool3 > Tool name > Name: axial_end > Enter Please use the default settings for tool working direction. This completes the entries on Tools page for Lesson 3. Input generator: Tube Enter the data for the semi finished tube: Tube centerline, outer tube diameter, material data, etc. The tube centerline for this lesson is provided in IGES–format which can be imported as follows:

Tube

Axis > Import ... Import line (s) > Format: IGES > OK > Select a file > Files: hy_lesson_03_axis.igs > OK Program: afmesh_3.1 > OK After meshing is complete, select the tube centerline in the main window using the right mouse button (Fig. 3.4). Select curve > OK


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Fig. 3.4

Center axis This example features a circular cross section. Therefore, definition can be achieved using the tube outer diameter. Tube

Cross section > Circle ... Cross section - Circle > Outer diameter: 51 > OK


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Tube position and material (FeP04_1) are according to default values (Fig. 3.5). Fig. 3.5

Input data on Tube page Input generator: Lube Lube

Lubrication > Constant > Constant > User defined: 0.15 Input generator: Process Next, define process steps prebending, annealing and tube hydroforming. Prebending Add process step ... Add process step > Type of process step > Prebending > Add process step

Process


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Process

Prebending > Process Step > Type: Prebending > End locked Annealing After prebending, define the process step annealing. This stress relieving procedure may be added after each forming process. Annealing provides better material forming capabilities for the main forming process. For calculation purposes, this is achieved by resetting stresses and strains in the part, yet saving the tube thickness values. You may also change the material properties during annealing.

Fig. 3.6

Definition of annealing • Initial material: Base material (before annealing) • New material: New material data (after annealing) Upon working with default–values, AutoForm–Hydro will calculate with the r–values data. Optionally you can choose a material www.forum.alghaform.com

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Lesson 3: Definition of Time–dependent Pressure– and Tool Control from the AutoForm database or create a user defined material (e. g. via Input … on Tube page) or by file import. • View: Displays stress–strain–curve, forming limit diagram and materials’ r–values. • Import: Import of a material file (*.mat) Defining the annealing process: Add process step ... Add process step > Type of process step > Annealing > Insert position > hydroforming > Insert before > Add process step

Process

Please use default values for annealing (Initial material, New material). Tube Hydroforming The main, final process step is hydroforming. hydroforming > Process step > Type: Hydroforming > Pressure Tool control > Show all > die > Control mode: Stationary

Process

Axial tool movement (axial_start and axial_end) is described by a function of time and displacement. hydroforming > axial_start > Control mode: Displcmnt Forming step - tool setup > Time variable displacement Pressing the button Time variable displacement activates the box Time - Displacement - Table in dialog Forming step - tool setup activated.


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control This allows for a definition of tool movement dependent on time. Fig. 3.7

Dialog: Forming step - tool setup • Add: Allows for definition of data sets (Time - Displacement). • From start: The input is defined for beginning of the process. If the data is not sufficient for the entire process step, the pressure value will be kept constant until end of process is reached. • From end: If pressure is known at the end of the process, the definition may start from there. Input data in the box will start at the end of the process and calculate backwards. • At end: In this case the pressure–line will be used in the defined direction. However, the final value is moved towards the ends of the process step. It may happen that the pressure–line is unknown at the beginning. In this case, the first pressure value will be used until time–control is activated. For this lesson please use the following settings in the Forming step - tool setup dialog box: Time: 0 > Displacement: 0 Time: 10 > Displacement: 4 > Add Time: 40 > Displacement: 5 > Add Time: 100 > Displacement: 5 > From start > Set


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Lesson 3: Definition of Time–dependent Pressure– and Tool Control For axial_end–tool use data according to tool movement of axial_start. hydroforming > axial_end > Control mode: Displcmnt Forming step - tool setup > Time variable displacement Time: 0 > Displacement: 0 Time: 10 > Displacement: 4 > Add Time: 40 > Displacement: 5 > Add Time: 100 > Displacement: 5 > From start > Set Finally, enter the time controlled pressure increase. The increase of pressure in the active media is defined similar to the way you have specified the axial tool displacement. Process

hydroforming > Hydroforming > Pressure: No pressure Pressure > Time variable Pressing the button Time variable activates the field Time variable pressure in the Pressure window. This allows for definition of pressure increase as a function of time (Fig. 3.8).

Fig. 3.8

Dialog: Pressure Please use the following values as input: Time: 0 > Pressure: 0 Time: 10 > Pressure: 10 > Add Time: 40 > Pressure: 40 > Add Time: 100 > Pressure: 100 > From start > Set www.forum.alghaform.com

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Lesson 3: Definition of Time–dependent Pressure– and Tool Control Note: Note You may use the same time steps for pressure increase and displacement of axial cylinders. In this case, process control will be by pressure–displacement. Finally, enter the process time for forming. By default, this is 500 seconds. For this process, adjustment is necessary because tool displacement was set to 100 seconds during time–pressure–development. Process

hydroforming > Duration > During time > Time: 100 The complete hydroforming process should look like Fig. 3.9 now.

Fig. 3.9

Definition of hydroforming process Input generator: Control These default values can be used for calculation (Fig. 3.10). www.forum.alghaform.com

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Lesson 3: Definition of Time–dependent Pressure– and Tool Control It is recommended to switch off the option WriteRestart in Main. Switch on Contact distance above under Rslts.

Control Fig. 3.10

Control–Main page Start of Simulation File > Save

Input generator

Job > Start simulation/View log … Start job > Program: afhydro_3.1 > Start


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Lesson 4: Simulation of Hydroforming using Counterpunch

6. 4 Lesson 4: Simulation of Hydroforming using Counterpunch A tube is formed by prebending, followed by inner pressure forming with time dependent pressure increase and axial tool movement. At first the lateral tool, counter tool and axial tool are defined. Then the forming process is specified by a time dependent pressure control and tool movement. Fig. 4.1

Part geometry Preparation of simulation Open a new simulation file: File > New ... > New file > File name: hy_lesson_04 > OK Geometry generator opens. Importing and Meshing the CAD geometry The CAD tool data for this example is provided in IGES – format. Geometry generator

File > Import ... Format: IGES > OK > Select a file > Files: hy_lesson_04_tools.igs > OK > Program: afmesh_3.1 > OK www.forum.alghaform.com

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Lesson 4: Simulation of Hydroforming using Counterpunch Close the Geometry generator. Geometry generator

File > Dismiss Generate simulation input Model > Input generator Simulation type > Simulation type: Hydro > Tube thickness: 1.2 > OK The tube shall have a wall thickness of 1.2 mm in this example. Input generator: Title

Title

Title: hy_lesson_04 (training, date) Input generator: Tools Definition of lateral tool In this example only one lateral tool (die) is defined.

Tools

die > Geometry > Reference ... Reference tool geometry > Pick faces Now the necessary patches for tool will be selected (Fig. 4.2). Ctrl – X (View from +X) Select patches in main display with right mouse button – Shift key and activate patches with option Activate in Reference tool geometry menu. Reference tool geometry > Activate > OK


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Lesson 4: Simulation of Hydroforming using Counterpunch Fig. 4.2

Necessary patches for lateral tool Default values for working direction and stiffness will be accepted (Fig. 4.3).


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Inputs for lateral tool on Tools page Definition of counter tool Use of a counter tool is necessary in hydroforming process, if special features are to be formed out of tube, e.g. a T–form. The forming of these features and the material flow can be controlled with a counter tool. Cracks would occur if such counter tools were not used. Next is the setup for the counter tool. Tools

Add tool … Add tool > Type of tool: Lateral > Default tool settings: Use settings of tool: die > Add tool For this tool name, the geometry working direction must be defined.


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Lesson 4: Simulation of Hydroforming using Counterpunch Tools

tool2 > Tool name > Name: countertool > Enter countertool > Geometry: Reference ... Reference tool geometry > Pick faces Select necessary patches for the counter tool (Fig. 4.4). Select patches in main display with right mouse button – Shift key and activate patches with option Activate in Reference tool geometry menu. Reference tool geometry > Activate > OK

Fig. 4.4

Necessary patches for counter tool Working direction of counter tool must be defined. Two possibilities exist: • In the field named Working direction a vector can be specified (Fig. 4.5). • With the Copy from option a vector can be imported from CAD (Fig. 4.5).


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Inputs for counter tool on Tools page In this example the Copy from option is used. To use Copy from option, curves must be imported first. Two possibilities exist: • Use of Curve managers • Import of curves on Tube page option Axis Import Option 1: Use of Curve managers Model > Curve manager ... Curve manager opens. (Fig. 4.6) Curve manager > File > Import ...


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Curve manager Import lines menu opens. Import line(s) > Format: IGES > OK > Select a file > Files: hy_lesson_04_axis.igs > OK > Program: afmesh_3.1 > OK Imported lines are displayed in main display and in Curve manager as Curve 1 and Curve 2. These two lines are the center line of the tube and working direction of the counter tool respectively. Close Curve manager. Curve manager > File > Dismiss Use Copy from on Tools page of Input generator to define working direction. countertool > Working direction: Copy f. ... Select curve menu opens. Select green line with right mouse button. In Curve manager it can be seen that green line is Curve 2. Select curve > OK AutoForm - Question menu for determination of orientation opens. AutoForm - Question > Keep Option 2: Use Import option on Tube page. Tube

Axis > Import … www.forum.alghaform.com

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Lesson 4: Simulation of Hydroforming using Counterpunch Import line(s) > Format: IGES > OK > Select a file > Files: hy_lesson_04_axis.igs > OK > Program: afmesh_3.1 > OK Imported lines are displayed in main display and in Curve manager as Curve 1 and Curve 2. Close Select curve menu. Select curve > Cancel Use Copy from to define working direction. countertool > Working direction: Copy f. ... Select curve menu opens. Select green line with right mouse button. In Curve manager, it can be seen that green line is Curve 2. Select curve > OK AutoForm - Question menu for determination of orientation opens. AutoForm - Question > Keep Counter tool must be positioned using Move. countertool > Working direction > Move: -10 Inputs on Countertool page are completed. Definition of axial tools Add tool … Add tool > Type of tool: Axial start > Use default setting > Add tool

Tools

tool3 > Tool name > Name: axial_start > Enter The tool tool3 has been renamed axial_start. axial_start > Working direction: Automatic Last tool to define is axial_end. Procedure is the same as for axial_start. www.forum.alghaform.com

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Lesson 4: Simulation of Hydroforming using Counterpunch Tools

Add tool … Add tool > Type of tool: Axial end > Use default setting > Add tool tool4 > Tool name > Name: axial_end > Enter axial_end > Working direction: Automatic Inputs for tools are completed. Input generator: Tube Tube center line must be specified. Curves are already imported. Tube center line can be defined using Copy from option.

Tube

Axis > Copy from … Select tube center line with right mouse button. Select curve > OK Another input is the tube–profile. In this example, it is a circular tube, so the profile can be specified by specifying the outer diameter.

Tube

Cross section > Circle ... Cross section - Circle > Outer diameter: 60 > OK


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Lesson 4: Simulation of Hydroforming using Counterpunch Default values are taken for the position and material (FeP04_1) (Fig. 4.7) Fig. 4.7

Inputs for tube on Tube page Input generator: Lube Lubrication > Constant > Constant: User defined: 0.1 Input generator: Process Process steps Prebending and Hydroforming must be defined. Prebending Process

Add process step ... Add process step > Type of process step > Prebending > Add process step prebending > Process Step >Type: Prebending: End locked


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Lesson 4: Simulation of Hydroforming using Counterpunch Attention: axial_start) Attention After Prebending, Prebending the free end of the tube (axial_start axial_start is not perpendicular to the tube center line. This is due to bending of the tube. Therefore, the tube center line must be shortened to avoid problems in the following simulation. Tube

Axis > Edit ... Curve editor opens and the tube center line is displayed in main display.

User interface

Ctrl – X (View +X) Select last point with the right mouse button (Fig. 4.8).

Fig. 4.8

Display of tube center line in edit mode Coordinates of selected point are displayed in Curve editor. Modify y–coordinate (Fig. 4.9). Curve editor > Base > Y: 10 > OK


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Curve editor Hydroforming Now Hydroforming must be defined (Fig. 4.10). Select subpage hydroforming on the Process page. Process

hydroforming > Process step > Type: Hydroforming: Pressure Tool control > Show all die > Control mode: Stationary Tool movement of counter tool and axial tool (axial_end) are described by a time–dependent displacement function. Tool movement of axial tool axial_start is not preferred for this process since geometric. Wrinkles might occur. countertool > Control mode: Displcmnt Forming step - tool setup >Time variable displacement Buttons Time variable displacement activates field Time - Displacement - Table in Forming step - tool setup menu, so that tool movement can be specified as being time–dependent. Use following values: Time: 0 > Displacement: 0 Time: 40 > Displacement: 2 > Add Time: 80 > Displacement: 4 > Add Time: 120 > Displacement: 6 > Add Time: 160 > Displacement: 8 > Add Time: 200 > Displacement: 10 > From start > Set


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www.alghaform.com

Lesson 4: Simulation of Hydroforming using Counterpunch Repeat for tool axial_end. axial_end > Control mode: Displcmnt For this lesson, the following values in the Forming step - tool setup dialog are should be defined: Use following values: Time: 0 > Displacement: 0 Time: 40 > Displacement: 2 > Add Time: 80 > Displacement: 4 > Add Time: 120 > Displacement: 6 > Add Time: 160 > Displacement: 8 > Add Time: 200 > Displacement: 10 > From start > Set Tool axial_start is set to Stationary: axial_start > Control mode: Stationary Last input is the time–dependent pressure function. hydroforming >Hydroforming > Pressure: No pressure Pressure >Time variable Button Time variable activates the Time variable pressure input field. Time: 0 > Pressure: 0 Time: 40 > Pressure: 10 > Add Time: 80 > Pressure: 15 > Add Time: 120 > Pressure: 20 > Add Time: 160 > Pressure: 30 > Add Time: 200 > Pressure: 40 > From start > Set Duration has to be specified. hydroforming > Duration > During time > Time: 200


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Definition of hydroforming process Input generator: Control WriteRestart OFF Contact distance above ON Start the Simulation File > Save

Input generator

Job > Start simulation Start job > Program: afhydro_3.1 > Start


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AutoForm Hydro

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