DESIGN OF I.C ENGINE CAM SHAFT
A camshaft is a shaft to which a cam cam is is fastened or of which a cam forms fo rms an int integr egral al part. Camshafts are responsible for the accurately-timed fuel injections required by internal combustion engines. Camshafts have multiple cams on them, which are used to open valves through either direct contact or pushrods. A camshaft is directly coupled to the crankshaft, so that the valve openings are timed accordingly. accordingly. Then with the use of C!" three-dimensional model of the cam shaft is obtained. "nce the CA# model is obtained, the part is analy$ed using %"&'# (")% (")% simula simulatio tion n tool tool by applyi applying ng chille chilled d iron iron materi material al and the loads loads are are applied. The materials used in the camshaft depend upon the quality and type of engine engine being being manufact manufactured. ured. *or most mass-prod mass-produced uced automobil automobiles, es, chilled chilled cast iron is iron is used. This This material is a good choice for high volume volume production. A chilled iron camshaft has a resistance against wear because the camshaft lobes have been chilled, generally making them harder. (hen making chilled iron castings, other elements are added to the iron before casting to make the material more suitable for its application.
INTRO IN TRODUC DUCTI TION ON CAM: A projection on a rotating part in machinery, designed to make sliding
contact with another part while rotating and to impart reciprocal or variable motion to it. Cams are used to convert rotary motion into reciprocating motion
CAMSHAFT: A shaft with one or more cams attached to it, e.g. working of valves
in an internal combustion engine is controlled by camshaft. Cam shaft is called the +brain of the engine.
CAM TERMINOLOGY
INTRO IN TRODUC DUCTI TION ON CAM: A projection on a rotating part in machinery, designed to make sliding
contact with another part while rotating and to impart reciprocal or variable motion to it. Cams are used to convert rotary motion into reciprocating motion
CAMSHAFT: A shaft with one or more cams attached to it, e.g. working of valves
in an internal combustion engine is controlled by camshaft. Cam shaft is called the +brain of the engine.
CAM TERMINOLOGY
Base Circe: The smallest circle centered on the cam rotation ais, and tangent to
the cam surface. The si$e of the base circle is dictated by spatial restrictions of the application.
Trace !"i#t: A theoretical point on the follower, corresponding to the point of a
fictitious knife-edge follower. follower. 't is used to generate the pitch curve. 'n the case of a roller follower, follower, the trace point is at the center of the roller.
H"mee $"si H"m $"siti"# ti"#:: Th Thee ori rien enta tati tion on of th thee ca cam m th that at co corr rres espo pond ndss to
displacement
on a
curve.
Refere#ce Circe %"r !rime circe&: A circle centered at the cam ais whose radius
is equal to the distance to the trace point. 't is the smallest circle from the cam center through the pitch curve
$ress're A#(e: The angle between the direction of motion of the follower and the
direction of the cam contact force is called pressure angle. /ressure angle should not eceed 0
.
$itch c'r)e1 The path generated by the trace point at the follower is rotated about
a stationary cam. *"r+i#( c'r)e1 The working surface of a cam in contact with the follower. *or
the knife-edge follower of the plate cam, the pitch curve and the working curves coincide. 'n a close or grooved cam there is an inner profile and an outer working curve.
CAM SHA$E
2.
$LATE
CAM " DISC
CAM1
The follower moves in a plane perpendicular to the ais of rotation of the camshaft. A translating translating or a swing arm follower must be constrained to maintain contact with the cam profile. 3.
GROO,ED
CAM or c"se-
This is a plate cam with the follower riding in a groove in the face of the cam.
Gr"")e- cam
cam1
2.
CYLINDRICAL
CAM OR
BARREL
CAM
The roller follower operates in a groove cut on the periphery of a cylinder. The follower may translate or oscillate. 'f the cylindrical surface is replaced by a conical one, a conical cam results 3.
END CAM
This cam has a rotating portion of a cylinder. The follower translates or oscillates, whereas the cam usually rotates. The end cam is rarely used because of the cost and the difficulty in cutting its contour.
Ci#-rica cam a#- E#- cam
MOTION OF THE CAM
(hen the cam turns through one motion cycle, the follower eecutes a series of events consisting of rises, dwells and returns. Rise is the motion of the follower away from the cam center, -/e is the motion during which the follower is at rest4 and ret'r# is the motion of the follower toward the cam center.
Lift:
5
&obe lift is the distance the lifter moves in one direction
5
&obe lift is the difference in measurement between the nose of the lobe and the base circle of the lobe
5
6alve lift is what most people are taking about when they refer to lift and is simply lobe lift multiplied by the rocker arm ratio
MATERIALS USED IN CAMSHAFT:
Camshaft material is the most important detail in stopping premature wear of performance camshafts. There are various materials that camshafts are manufactured from1-
CAST IRONS
0. HARDENABLE IRON:
This is 7rade 28 cast iron with an addition of 29 chrome to create : to 89 free carbide. After casting, the material is flame;or induction hardened, to give a ockwell hardness of :3 to :< on the C %cale. 't is not the most suitable material for performance camshafts in overhead cam =">C? engines.
3.S$HEROIDAL GRA$HITE CAST IRON 1NO*N AS SG IRON:
A material giving similar characteristics to hardenable. 'ts failing as a camshaft material is hardness in its cast form, which tends to scuff bearings in adverse conditions. The material will heat treat to :3 to :@ ockwellC. This material was used by *iat in the 2@Bs
0. CHILLED CHROME CAST IRON: Chilled iron is 7rade 28 cast iron with 29 chrome. (hen the camshaft is cast in the foundry, machined steel moulds the shape of the cam lobe are incorporated in the mould. (hen the iron is poured, it hardens off very quickly =known as chilling?, causing the cam lobe material to form a matri of carbide =this material will cut glass? on the cam lobe. This material is eceedingly scuff-resistant and is the only material for producing quantity ">C performance camshafts.
CONCLUSION OF CAST CAMSHAFTS:
(hen purchasing a camshaft, enquire which material the camshafts are produced from. A chilled iron camshaft may be more epensive, but its resistance to wear in all conditions, far eceeds any other type of cast iron.
STEEL CAMSHAFTS
0. CARBON STEEL 2 EN3 %BS456 636M76& 8EN44%BS456 656M99&:
sed mainly in the 20 to 2D: period and is currently used for induction hardened camshafts in conjunction with roller cam followers, due to the throughhardening characteristics of the material.
. ALLOYED STEELS 2 EN;90 AISI 3<6 a#- EN;7:
sed by Eritish &eyland in the A %eries and E %eries engine and best when run against a chilled cam follower. ;. NITRIDING STEEL 2 EN76B:
The best steel for camshafts. (hen nitrided it gives a surface hardness and finish similar to chilled iron.(e used this when replacing chilled iron camshafts in competition engines. This material is used on several of the current *2 engines.
CONCLUSION
'n general, steel is a good camshaft material. >owever, the type of steel has to be matched with the cam follower it runs against, as different grades of steel have different scuff characteristics.
DESIGN $ROCEDURE:
$r"fie Desi(# acc"r-i#( t" re='ireme#t:
#esign a cam for operating the ehaust valve of an oil engine. 't is required to give equal uniform acceleration and retardation during opening and closing of the valve each of which corresponds to <F of cam rotation. The valve must remain in the fully open position for 3F of cam rotation.
The lift of the valve is 08.: mm and the least radius of the cam is D mm. The follower is provided with a roller of radius of 3 mm and its line of stroke passes through the ais of the cam.
$r"!"se- $r"fie Desi(#: C"#str'cti"#
*irst of all, the displacement diagram, as shown in *ig 2, is drawn as discussed in the following steps1
2. #raw a hori$ontal line A%T/ such that A% represents the angular displacement of the cam during opening = i.e out stroke? of the valve =equal to <F?, to some suitable scale. The line %T represents the dwell period of 3F i.e the period during which the valve remains fully open and T/ represents the angular displacement during closing =i.e return stroke? of the valve which is equal to <F.
fi(. 0
2. #ivide A% and T/ into any number of equal even parts =say si?. 3. #raw vertical lines through points , 2, 3,0 etc. and equal to lift of the valve i.e 08.: mm. 0. #ivide the vertical lines 0f and 0BfB into si equal parts as shown by the points a, b, c. .. and aB, bB , cB in figure 2. D. %ince the valve moves with equal uniform acceleration and retardation, therefore the displacement diagram for opening and closing of a valve consists of double parabola. :. Complete
the
displacement
diagram
as
shown
in
*ig.
2
Fi(>
Gow the profile of the cam, with a roller follower when its line of stroke passes through the ais of cam as shown in *ig 3
METHODS OF MANUFACTURING:
0. CASTING:
Chilled cast iron is primarily used for production of cam shaft. The development of automobile industry and engine power brings up more advance requirement for properties of camshaft. 'n casting process, there are more chances of casting defects such as shrinkage defect, porosity, crack, insufficient pouring. >owever for higher loads in roller contact, cast camshafts with induction hardened cam lobes can be used.
3. FORGING: *orged or manufactured from a steel bar camshafts are also used for certain high loaded diesel engines. These are produced on computer-controlled forging systems with integrated heat treatment or machined from steel bar.
;. MACHINING: Hachining is necessary for giving final dimension to the cam.
A. (hile using Casted or *orged CAH only *inal Hachining is require to achieve
final si$e within the required tolerances. 'n this process casted or forged CAH are in the required shape but their si$e is maintained by machining and finishing operation.
B. (hile sing Hetal Eillet =metal rod?, the profile of cam is obtained by removing
ecess material which from metal billet. 'n this process only machining is required to manufacture CAH.
A detailed description of the processes for mass manufacturing is as follows1
2.TURNING ? DRILLING1 The raw forging is put in this machine and center drilling and turning on one side is done here.
3. TURNING: >ere the turning of the < journals takes place. There are D tools used for this turning I ough, Geutral, &eft and ight tool. Also, 7rooving and /arting operation is performed on the left side of the shaft.
0. DRILLING: This machine drills the diameter D.: dowel hole which is used as reference for further operations.
D. GRINDING @OURNALS: >ere grinding and finish grinding of the < journals takes place. Carborundum wheels are used for grinding.
:. GRINDING ON FACE: An angular grinding wheel is used for the face grinding operation. At this stage, inspection is done after every 2 components using gauges.
<. DRILL DO,EL HOLE: 7rinding of the Cam is done here. The dowel hole is taken as the reference.
8. LA$$ING:
To give superfinish in microns, lapping is done using lapping paper on the Cams. @. SLITTING: This machine makes a slit in the right side of the shaft to fit in the engine. The cutter used is a %aw cutter and pneumatic deburring is done here.
. AIR ? *ATER CLEANING: This is the (ashing Hachine where water and air jets are used to clean the component of dust, oil, chips etc.
2. INS$ECTION: This is a Heasuring Hachine used to check for tolerances unouts and #iameters of journals = all < and center D?. The machine then declares the component as "), G7, or EA#.
INTRODUCTION TO CAD
C"m!'ter>ai-e- -esi(# =CAD?, also known as c"m!'ter>ai-e- -esi(# a#-rafti#( =CADD?, is the use of computer technology for the process of design and
design-documentation. Computer Aided #rafting describes the process of drafting with a computer. CA## software, or environments, provides the user with inputtools for the purpose of streamlining design processes4 drafting, documentation, and manufacturing processes. CA## output is often in the form of electronic files for print or machining operations. The development of CA##-based software is in direct correlation with the processes it seeks to economi$e4 industry-based software =construction,
manufacturing,
etc.?
typically
uses
vector-based
=linear?
environments whereas graphic-based software utili$es raster-based =piilated? environments.
CA## environments often involve more than just shapes. As in the manual drafting of technical and engineering drawings, the output of CA# must convey information, such as materials, processes, dimensions, and tolerances, according to application-specific conventions. CA# may be used to design curves and figures in two-dimensional =3#? space4 or curves, surfaces, and solids in three-dimensional =0#? objects. CA# is an important industrial art etensively used in many applications, including automotive, shipbuilding, and aerospace industries, industrial and architectural design, prosthetics, and many more. CA# is also widely used to produce computer animation for special effects in movies, advertising and technical manuals. The modern ubiquity and power of computers means that even perfume bottles and shampoo dispensers are designed using techniques unheard of by engineers of the 2<s. Eecause of its enormous economic importance, CA# has been a major driving force for research in computational geometry, computer graphics =both hardware and software?, and discrete differential geometry. The design of geometric models for object shapes, in particular, is often called computer-aided geometric design
=CA7#?.Current
computer-aided
design
software packages range from 3# vector -based drafting systems to 0# solid and surface modellers. Hodern CA# packages can also frequently allow rotations in three dimensions, allowing viewing of a designed object from any desired angle, even from the inside looking out. %ome CA# software is capable of dynamic mathematic modeling, in which case it may be marketed as CADD J computeraided design and drafting.
CA# is used in the design of tools and machinery and in the drafting and design of all types of buildings, from small residential types =houses? to the largest commercial and industrial structures =hospitals and factories?. CA# is mainly used for detailed engineering of 0# models and;or 3# drawings of physical components, but it is also used throughout the engineering process from conceptual design and layout of products, through strength and dynamic analysis of assemblies to definition of manufacturing methods of components. 't can also be used to design objects. CA# has become an especially important technology within the scope of computer-aided technologies, with benefits such as lower product development costs and a greatly shortened design cycle. CA# enables designers to lay out and develop work on screen, print it out and save it for future editing, saving time on their drawings. T!es "f CAD S"ft/are
2D CAD Two-dimensional, or 3#, CA# is used to create flat drawings of products and structures. "bjects created in 3# CA# are made up of lines, circles, ovals, slots and curves. 3# CA# programs usually include a library of geometric images4 the ability to create Ee$ier curves, splines and polylines4 the ability to define hatching patterns4 and the ability to provide a bill of materials generation. ;D CAD
Three-dimensional =0#? CA# programs come in a wide variety of types, intended for different applications and levels of detail. "verall, 0# CA# programs create a realistic model of what the design object will look like, allowing designers to solve potential problems earlier and with lower production costs. %ome 0# CA#
programs include Autodesk 'nventor, Co Create %olid #esigner, /ro;!ngineer %olid !dge, %olid (orks, nigraphics GK and 6K CA#, CAT'A 6:.
3D Wireframe and Surface Modeling CA# programs that feature 0# wireframe and surface modeling create a skeletonlike inner structure of the object being modeled. A surface is added on later. These types of CA# models are difficult to translate into other software and are therefore rarely used anymore.
Solid Modeling %olid modeling in general is useful because the program is often able to calculate the dimensions of the object it is creating. Hany sub-types of this eist. Constructive %olid 7eometry =C%7? CA# uses the same basic logic as 3# CA#, that is, it uses prepared solid geometric objects to create an object. >owever, these types of CA# software often cannot be adjusted once they are created.
INTRODUCTION: CREO 0. CAD
Computer aided design =cad? is defined as any activity that involves the effective use of the computer to create, modify, analy$e, or document an engineering design. CA# is most commonly associated with the use of an interactive computer graphics system, referred to as cad system. The term CA#;CAH system is also used if it supports manufacturing as well as design applications. . I#tr"-'cti"# t" CREO
C!" is a suite of programs that are used in the design, analysis, and manufacturing of a virtually unlimited range of product. 'n C!" we will be dealing only with the major front Iend module used for pan and assembly design
and model creation, and production of engineering drawings Schamtic+""%7& . There are wide ranges of additional modules available to handle tasks ranging from sheet metal operations, piping layout mold design, wiring harness design, GC machining and other operations. 'n a nutshell, C!" is a parametric, feature-based solid modeling system, Feat're ase- means that you can create part and assembly by defining feature like etrusions, sweep, cuts, holes, slots, rounds, and so on, instead of specifying low-level geometry like lines, arcs, and circleL features are specifying by setting values and attributes of element such as reference planes or surfaces direction of creation, pattern parameters, shape, dimensions and others. $arametric means that the physical shape of the part or
assembly is driven by the values assigned to the attributes =primarily dimensions? of its features. /arametric may define or modify a featureBs dimensions or other attributes at any time. *or eample, if your design intent is such that a hole is centered on a block, you can relate the dimensional location of the hole to the block dimensions using a numerical formula4 if the block dimensions change, the centered hole position will be recomputed automatically.
+%olid Hodeling means that the computer model to create it able to contain all the information that a real solid object would have. The most useful thing about the solid modeling is that it is impossible to create a computer model that is ambiguous or physically non-reali$able. /TC was founded in 2@:, by %amuel /eisakhovich 7insberg, who previously worked at /rime Computer, Computer vision =C6? and Applicon. /ro;!G7'G!! =a.k.a. /ro;!?, the companyMs first product, shipped in 2@@. Nohn #eere became /TCBs first customer. "nce an initial version of /ro;!G7'G!! was developed, the company received venture capital funding from Charles
iver
Associates
and
%teve
(alske
became
the
C!".
/ro;!G7'G!! was the first commercially successful parametric feature based solid modeler. Through a combination of innovative technology, and no-holds barred sales tactics, /TC quickly became a major force in the CA# industry. 'ts strong ascent continued unabated until the mid-2s, when the introduction of Hicrosoft (indows GT, and the availability of commercial geometric modeling libraries opened the door to a new generation of low-cost competitors and /TCMs reputation for overly aggressive sales tactics alienated many of its customers. These competitors, symboli$ed by %olid works, squee$ed /TC from the bottom, while more established companies like ni graphics and 'EH held the
Mhigh groundM in automotive and aerospace industries. /TCMs sales began a multiyear decline from which it took years to recover. 't took a new CA# product and an epanded product line, but /TC has been able to transform itself over the past 2 years into the third largest provider of /roduct &ifecycle Hanagement software. "n #ecember 3, 3< %tandard L /oorMs bumped /TC off its %L/ : 'nde, and replaced it instead with the newly spun-off natural gas company %pectra !nergy Corp. =GO%!1 %!?. /arametric then bumped /ier 2 'mports 'nc. =GO%!1 /'?, a retailer of home furnishings, down one spot and off the bottom of the %L/ Hidcap D 'nde 'n 3@, /TC once again achieved revenues of over P2 billion something it had not been able to accomplish since 2. Creo !lements;/ro, a product formerly known as /ro;!G7'G!! is a parametric, integrated 0# CA#;CAH;CA! solution created by /arametric Technology Corporation =/TC?. 't was the first to market with associative solid software. The application runs on Hicrosoft (indows platform, and provides solid modeling, assembly modeling and drafting, finite element analysis, and GC and tooling functionality for mechanical engineers. The /ro;!G7'G!! name was changed to Creo !lements;/ro on "ctober 3@, 32, coinciding with /TCBs announcement of Creo, a new design software application suite.
C!" !lements;/ro =formerly /ro;!G7'G!!?, /TCMs parametric, integrated 0# CA#;CAH;CA! solution, is used by discrete manufacturers for mechanical engineering, design and manufacturing.
Companies use Creo !lements;/ro to create a complete 0# digital model of their products. The models consist of 3# and 0# solid model data which can also be used downstream in finite element analysis, rapid prototyping, tooling design, and CGC manufacturing.
All data is associative and interchangeable between the CA#, CA! and CAH modules without conversion. A product and its entire bill of materials =E"H? can be modeled accurately with fully associative engineering drawings, and revision control information. The associativity functionality in Creo !lements;/ro enables users to make changes in the design at any time during the product development process and automatically update downstream deliverables. This capability enables concurrent engineering design, analysis and manufacturing engineers working in parallel and streamlines product development processes. Almost thirty five years, /ro !ngineer has been the most powerful and popular three dimensional computer aided design software in the industry. 't has the most
variety in terms of advancement in product development capabilities that are currently available on the market. The current version of /ro !ngineer is simple to use and learn. 't is also very affordable, no matter whether you have small or medium si$e company. Easically, it has every functionality that a small business requires to be successful. There are many client testimonials that provide product feedback. This is very important because it is always good to hear it straight from your peers. Hany people who represent the small business sector were recently asked about why they used this particular CA# software. The testimonials were located in various countries and represented various industries, too. They eplained how the software provided a positive impact on their operations and the feedback was quite comprehensive. Almost everyone has business operations that involve daily tasks, including product design. %ome types of projects and product design include the creation of an overall design for the primary components. This is an assembly type that could be assisted by the /ro !ngineer program. "nce you have created the digital model you may need to apply plastics on the form. The software allows you to create the styling and surfacing as it is able to simulate the characteristics of different materials. This step will then drive the
design for all the product sub-components. The pro !ngineer software allows you to drive the complete design from a single primary file. (hen this product is used, be sure to be aware of the specifications and references in the very beginning of the project. 'f changes need to be made, the software can do it automatically. Eoth the measurements and the design of the components can be altered according to your desire. This creates very big opportunities for time saving processes, which is why this software program is such a powerful tool. (ithout the ability to make changes so easily, you would have to make drafts for every component on an individual basis. 'f for eample the complete dimensions of your design change, some types of software would force you to change each individual component where as/ro !ngineer allows you to change all the units and measurements easily in one go. 't can also be used for production. (hen three dimensional files are sent to a manufacturer, they can construct the tooling straight from the files that were sent. %ince the file is 0# and it has all the necessary measurements, it can save you from the task of needing to create the two dimensional sketches that the manufacturer used to have to have in order to review the part.
Oou can easily make call outs to the important measurements that you want them to perform total analysis on. This is a real time saver. 'n fact, it can save about twenty per cent of the time that you would generally spend on the whole process. 'f you need a powerful solution for your product development process, /ro !ngineer is a good choice, as it allows you to work more efficiently and with improved design verification.
There are si core C!" concepts. Those are1
•
%olid Hodeling
•
*eature Eased
•
/arametric
•
/arent ; Child elationships
•
Associative
•
Hodel Centric
The display of C!" will be as below 2 >ide the browser by clicking on the arrows at the right of the screen, as shown in the figure. Oou should now see the graphics area where parts will be displayed. 3 %elect Q*ileR -S Q%et (orking #irectoryR from the menu bar, and select the folder in which you downloaded the part. All work you do will be saved to the folder you set as the working directory. 0 %elect Q*ileR -S Q"penR from the menu bar, and select the part you downloaded.
; Ca!aiities a#- Be#efits:
2
Complete 0# modeling capabilities enable you to eceed quality arid time to arid time to market goals.
3 Haimum
production
efficiency
through
automated
generation
of
associative C tooling design, assembly instructions, and machine code. 0 Ability to simulate and analysis virtual prototype to improve production performance and optimi$ed product design. D Ability to share digital product data seamlessly among all appropriate team members : Compatibility with myriad CA# tools-including associative data echange and industry standard data formats.
7 Feat'res "f CREO
C!" is a one-stop for any manufacturing industry. 't offers effective feature, incorporated for a wide variety of purpose. %ome of the important features are as follows1
•
%imple and powerful tool
•
/arametric design
•
*eature-based approach
•
/arent child relationship
•
Associative and model centric
7.0. Sim!e a#- $"/erf' T""
C!" tools are used friendly. Although the eecution of any operation using the tool can create a highly comple model 7.. $arametric Desi(#
C!" designs are parametric. The term +parametric means that the design operations that are captured can be stored as they take place. They can be used effectively in the future for modifying and editing the design. These types of modeling help in faster and easier modifications of design. 7.;. Feat're>Base- A!!r"ach
*eatures are the basic building blocks required to create an object. C!" models are based on the series of feature. !ach feature builds upon the previous feature, to create the model =only one single feature can be modified at a time?.
!ach feature may appear simple, individually, but collectively forms a comple part and assemblies. The idea behind feature based modeling is that the designer construct on object, composed of individual feature that describe the manner in which the geometry supports the object, if its dimensions change. The first feature is called the base feature. 7.7. $are#t Chi- Reati"#shi!
The parent child relationship is a powerful way to capture your design intent in a model. This relationship naturally occurs among features, during the modeling process. (hen you create a new feature, the eisting feature that are referenced, become parent to the feature 7.9. Ass"ciati)e a#- M"-e Ce#tric
C!" drawings are model centric. This means that C!" models that are represented in assembly or drawings are associative. 'f changes are made in one module, these will automatically get updated in the referenced module. 9. CREO Basic Desi(# M"-es
(hen a design from conception to completion in pro;engineer, the design information goes through three basic design steps.
2
Creating the component parts of the design
3 Noining the parts in an assembly that records the relative position of the parts. 0 Creating mechanical drawing based on the information in the parts and the assembly. < Assem i# CREO :
Eottom-p #esign =Hodeling?1 The components =parts? are created first and then added to the assembly file. This technique is particularly useful when parts already eist from previous designs and are being re-used. 8.Top-#own #esign =Hodeling?1 The assembly file is created first and then the components are created in the assembly file. The parts are build relative to other components. seful in new designs 'n practice, the combination of Top-#own and Eottom-p approaches is used. As you often use eisting parts and create new parts in order to meet your design needs. #egrees of *reedom1 An object in space has si degrees of freedom. 5 Tra#sati"# I movement along K, O, and ais =three degrees of freedom?
5 R"tati"# I rotate about K, O, and ais =three degrees of freedom? Assembly Constraints1 'n order to completely define the position of one part relative to another, we must constrain all of the degrees of freedom. Mate, Align, and Insert Mate
Two selected surfaces become co-planar and face in opposite directions. This constrains 0 degrees of freedom =two rotations and one translation? Mate Offset
Two surfaces are made parallel with a specified offset distance . Align Coincident
Two selected surfaces become co-planar and face in the same direction. Can also be applied to revolved surfaces. This constrains 0 degrees of freedom =two rotations and one translation?. (hen Align is used on revolved surfaces, they become coaial =aes through the centers align?.
Align Offset
This can be applied to planar surfaces only4 surfaces are made parallel with a specified offset distance.
Align Orient
Two planar surfaces are made parallel, not necessarily co-planar, and face the same direction =similar to Align "ffset ecept without the specified distance?. Insert
This constrain can only be applied to two revolved surfaces in order to make them coaial =coincident?. Fundamentals of assembly in CREO :
'n pull down menu *ile, select new and then choose Assembly option.
A--i#( C"m!"#e#ts:
'n the pull-down menu, select
Insert SComponent S Assemble"r pick the Add
Component button in the right toolbar.
Erowse and open the file for the first component.
CREO M"-'es • • • • • •
%ketcher =3#? /art =0#? Assembly #rawing and #rafting %heet Hetal endering
Feat'res "f CREO e#(i#eeri#(:
/ro;engineering is a one-stop for any manufacturing industry. 't offers effective feature, incorporated for a wide variety of purpose. %ome of the important features are as follows1
•
%imple and powerful tool
•
/arametric design
•
*eature-based approach
•
/arent child relationship
•
Associative and model centric
Sim!e a#- $"/erf' T""
C!" tools are used friendly. Although the eecution of any operation using the tool can create a highly comple model $arametric Desi(#
C!" designs are parametric. The term +parametric means that the design operations that are captured can be stored as they take place. They can be used effectively in the future for modifying and editing the design. These types of modeling help in faster and easier modifications of design. Feat're>Base- A!!r"ach
*eatures are the basic building blocks required to create an object. C!" engineering wildfire models are based on the series of feature. !ach feature builds upon the previous feature, to create the model =only one single feature can be
modified at a time?. !ach feature may appear simple, individually, but collectively forms a comple part and assemblies. The idea behind feature based modeling is that the designer construct on object, composed of individual feature that describe the manner in which the geometry supports the object, if its dimensions change. The first feature is called the base feature.
$are#t Chi- Reati"#shi!
The parent child relationship is a powerful way to capture your design intent in a model. This relationship naturally occurs among features, during the modeling process. (hen you create a new feature, the eisting feature that are referenced, become parent to the feature.
Ass"ciati)e a#- M"-e Ce#tric
/ro;!ngineering wildfire drawings are model centric. This means that /ro;!ngineering models that are represented in assembly or drawings are associative. 'f changes are made in one module, these will automatically get updated in the referenced module.
CREO Basic Desi(# M"-es
(hen a design from conception to completion in pro;engineer, the design information goes through three basic design steps.
Creating the component parts of the design Noining the parts in an assembly that records the relative position of the parts. Creating mechanical drawing based on the information in the parts and the assembly.
C!" consider these steps as separate +modes, each with its own characteristics, files etensions, and relation with the other model. As you build a design model it is important to remember that a information, dimensions, tolerances, and relational formulas are passed from model to the net bi directional. This means that if you change your design at any model level. C!" reflect it all model levels automatically.'f it is planned ahead and the use associative features correctly, you can save significant time in the design and engineering change order process. Assem i# CREO: B"tt"m>U! Desi(# %M"-ei#(&:
The components =parts? are created first and then added to the assembly file. This technique is particularly useful when parts already eist from previous designs and are being re-used. Top-#own #esign =Hodeling?1 The assembly file is created first and then the components are created in the assembly file. The parts are build relative to other components. seful in new designs 'n practice, the combination of Top-#own and Eottom-p approaches is used. As you often use eisting parts and create new parts in order to meet your design needs. De(rees "f Free-"m:
An object in space has si degrees of freedom. 5 Tra#sati"# I movement along K, O, and ais =three degrees of freedom? 5 R"tati"# I rotate about K, O, and ais =three degrees of freedom? Assem C"#strai#ts:
'n order to completely define the position of one part relative to another, we must constrain all of the degrees of freedom. Mate, Align, and Insert Mate
Two selected surfaces become co-planar and face in opposite directions. This constrains 0 degrees of freedom =two rotations and one translation?
Mate Offset
Two surfaces are made parallel with a specified offset distance . Align Coincident
Two selected surfaces become co-planar and face in the same direction. Can also be applied to revolved surfaces. This constrains 0 degrees of freedom =two rotations and one translation?. (hen Align is used on revolved surfaces, they become coaial =aes through the centers align?. Align Offset This can be applied to planar surfaces only4 surfaces are made parallel
with a specified offset distance. Align Orient
Two planar surfaces are made parallel, not necessarily co-planar, and face the same direction =similar to Align "ffset ecept without the specified distance?. Insert
This constrain can only be applied to two revolved surfaces in order to make them coaial =coincident?. Ste!s f"r m"-ei#( "f cam shaft i# cre":
AU!trude material1
Solid Extrude
2. %elect the front plane and click at etrude icon . 't will get you into the sketching window. 3. sing a circle tool make a simple circle of your desired diameter =just for practicing? and click at ok button .
Now the creo parametric will show you the preview of your extrude. You can change the depth of extrude by moving the white square. To do this just click and hold at the white square and move your mouse to change the length.
Two types of extrude depth we can learn at this moment.
•
Blind
•
Symmetric
Blind option is shown in above figure and it is by default active. To use symmetric option click at extrude depth tool menu! and select the symmetric option you will see that extrude become equally distributed with reference to sketching plane.
I#tr"-'cti"# An etrude feature is based on a two-dimensional sketch. 't linearly etrudes a sketch perpendicular to the sketching plane to create or remove material. Oou can either select the sketch first or then start the !trude tool, or you can start the !trude tool and then select the sketch. 'n this eercise we will try to learn about •
S"i- Etr'-e
•
Etr'-e c't8A--
•
Etr'-e Thic+e# C't8A--
•
Ta!!er
Also we will use etrude types such as •
Bi#-
•
Smmetric
•
Thr"'(h a
•
Thr"'(h '#ti
•
T" seecte-
>ere is the dashboard option used in etrude tool. ' label it to show you the function of the representative option. S"i-: this option is selected by default to make solid etrude. S'rface: This can be used to etrude the sketch as surface. Etr'-e -e!th t"": is used to control etrude by specifying some
constraints. De!th )a'e: used to specify the dimension of depth. %ome etrude
types do not need this. I#)ert t"": used to change the direction of etrude opposite to the
reference direction. Rem")e materia: this tool is used to remove the material while
etruding. Thic+e# t"": is used to etrude as thick sheet. Thickness value can be
adjust by entering the value in bo =just right to the thicken tool?. The invert tool net to the thicken tool is used to specify the direction of thickness by three ways. 2. "ne side 3. Eoth sides1 thickness will be symmetric to the sketch boundary. 0. "ther side
(hen we click at the etrude depth tool a drop down menu will open in which you can see the following icons representing the specific conditions for etrude.one thing you should note that these option will be available when you will try to make etrude on eisting surface or model. 2?
Bi#-: this is the default option. 'n simple words the depth is blind
for program and we have to provide it. 3?
Smmetric: This option provides you the equal etrude on the
both side of sketching plane. 0?
T" #et: using this option you can stop etrude to very net
surface that etrude encountered. #epth dimension is not required for this option D?
Thr"'(h A: This option will generate etrude that through to the
whole model. #epth dimension is not required. :?
Thr"'(h '#ti: This option will cause etrude to stop at the
specified;selected surface and section must pass through the selected surface.
T" seecte-: it is just like the through until option ecept that
section -"es #"t have to pass through the selected surface.
I#sert !a#e !arae t" etr'-e serface
Etr'-e /ith the sha!e "f cam !r"fie as sh"/#
Ma+e i#er !atter# "f a")e etr'-e- feat're
