Metal Spinning for Forming Non-circular Shapes Hirohiko Arai Low-Formability-Materials Processing Group Advanced Manufacturing Research Institute National Institute of Advanced Industrial Science & Technology (AIST)
[Contents] 1. Metal Spinning 2. Forming of Non-circular Shapes 2.1 Synchronous spinning 2.2 Force-controlled spinning 3. Development of Metal Spinning Machine
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[Metal Spinning] Roller
Roller
Blank
Mandrel
shear spinning
Mandrel Blank
conventional spinning
- Plastic forming process for metal sheet - Forcing material onto a rotating mandrel using a roller tool
Products of Metal Spinning
Aerospace parts
Industrial art
Nuclear power plant equipments
Semiconductor process & Medical equipments
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Merits of Metal Spinning • Only one mandrel → Low-cost setup • Small forming force → small machinery, little noise/vibration • Shapes that sheet metal stamping or deep drawing cannot make • Precision products and good surface finishing • Saving material compared with cutting process Limited production of a variety of products Prototyping and product development
[Robotic Metal Spinning] Metal Spinning Sense of force (Skilled worker) Small forming force Dexterous motion … Suitable Task for Robot Technology Limited production of a wide variety High added value … Profitability of Robot Intelligence
Metal Spinning + Robot Control Technique - Flexible and Intelligent Forming Process - New Application Area for Robot Control
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[Forming of Non-circular Shape] Metal Spinning ... Axisymmetric shape (circular cross-section)
Non-circular Product ・ Elliptical or polygonal cross-section ・ Eccentric or oblique axis ・ Surface embossing foregoing methods: special forming devices Ù Application of robot control
[Synchronous Spinning] Radial displacement
Final Shape B Blank shape A
x θ
Roller tool Desired Shape C
Radial displacement x = x(θ) of roller tool … synchronized with rotation angle θ
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Two-roller Metal Spinning Machine chuck
Main spindle
AC servo motor (1.3KW) x5 (Main spindle: servo control)
work
z’
x-axis range 100mm
z
z-axis range 200mm x,z rated force 5000N
roller
x
x’
x,z rated speed 0.25m/sec Main spindle 300rpm max. DNC from PC via Ethernet
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Forming of Elliptic Tube-end Pure Aluminum Tube (A1050TD-H) φ 50mm, t=1.5mm, length 100mm
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Curved and Oblique Spinning Roller moves in axial and radial directions
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[Force-Controlled Metal Spinning] Desired shape: Fitting material to mandrel Non-circular mandrel Controlling pushing force of forming roller Following contour of mandrel … Non-circular product (same shape as mandrel ) Velocity Control Roller Rotation Force Control
Mandrel Blank
Experimental Metal Spinning Machine
700mm
y-axis: 150mm
700mm
x-axis: 150mm
Roller Stator magnet
Gear
Motor
Force sensor Roller Mandrel
Force Sensor
Material + Mandrel
Actuator for roller : linear brushless servo motor Continuous force 1000 N, Peak speed 3.0 m/s
Actuator for mandrel : servo motor + planetary gear Continuous torque 14 Nm, Rated speed 270 rpm
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Examples of Non-circular Products (Pure Aluminum Sheet t=1.0mm)
Forming of Pyramid Shape … combination of synchronous and force-controlled spinning
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Synchronous spinning: approximate shape Force-controlled spinning: finishing
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[Development of Prototype Machine for Non-circular Shapes] Collaboration with a Company (Daito Spinning Co.) … developed a MS machine prototype driven by linear motor
Specifications of Prototype Width 2875mm x Depth 1820mm x Height 1895mm Ｘ-axis (radial): Linear Servo Motor, rated thrust 4000N Z-axis (axial): Servo Motor + Ball Screw, rated thrust 10000N Spindle: Servo Motor + Planetary Gear rated power 7.5kW, rated speed 375rpm Work: Max. diameter 400mm length 350mm Backup roller
Forming roller
Z-axis
Tailstock
X-axis
Spindle Mandrel
Blank holder
Knockout mechanism
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Examples of Non-circular Products
[Future Works] - Variety of Shape
Practical machine
forming know-how
- Stronger Force stainless steel thick material
- Faster Forming servo response
User companies Trial Jig & parts material design Process development
Machine manufacturer Sample parts AIST
Machine programming
Machine tuning Machine design Trial data experiment
Forming know-how
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“ROBOSPIN” Robotic Metal Spinning Machine for Non-circular Products - Non-circular shapes (elliptical, polygonal, eccentric, etc.) can be formed using robot control technology. - This technology is suitable for small production lots with a variety of designs, prototyping and product development because of the low tooling cost and short turnaround. The National Institute of Advanced Industrial Science and Technology (AIST) and Daitoh Spinning Co., Ltd. have jointly developed a novel metal spinning machine, "RoboSpin," which can form non-circular shapes. (1) A linear motor is adopted to actuate the forming roller and thus control the forming force rapidly. (2) The spindle is driven by a servo motor to exactly synchronize with the motion of the forming roller. RoboSpin can form various non-circular products with elliptical, eccentric and polygonal shapes, which conventional metal spinning machines cannot handle. “RoboSpin” Metal Spinning Machine
Forming a Pyramid Shape
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Examples of Non-circular Products
■ Development of RoboSpin ■ Metal spinning is a plastic forming process that shapes a metal sheet or tube by forcing it onto a rotating mandrel using a roller tool. It is widely used for making round hollow metal products in various industries, such as the automotive, aerospace, electronics, medical, lighting, architectural, etc. This forming process is suitable for limited production lots of a wide variety of products and it is particularly effective in prototyping and product development, since it needs only one mandrel, which costs much less than the dies for metal stamping or deep drawing. AIST has been studying metal spinning methods in which robot technologies are applied, with the aim of developing versatile and intelligent forming processes. In particular, AIST is conducting R&D on the metal spinning of noncircular shapes. Metal spinning products have been inherently limited to axisymmetric shapes that have circular cross sections around the rotation axis. However, there is a potential demand for non-circular products formed by metal spinning which have elliptical, polygonal, eccentric or other non-circular cross sections. Metal spinning will be used more widely if it can produce a variety of non-circular products. AIST and Daitoh Spinning Co., Ltd., a manufacturer specialized in metal spinning machines, have recently developed "RoboSpin" as a functional prototype of a metal spinning machine for forming non-circular products.
■ Methods of Forming Non-circular Shapes ■ RoboSpin performs two basic metal spinning actions to form non-circular products: force-controlled metal spinning and synchronous metal spinning. In Force-controlled Metal Spinning, a non-circular mandrel is used. The pushing force of the forming roller is controlled so that the material is forced onto the mandrel. Meanwhile, the forming roller is driven at a constant velocity parallel to the mandrel axis. The roller follows the contour of the mandrel to fit the material to the mandrel. Finally, a non-circular product of the same shape as the mandrel is fabricated.
Feeding velocity
Roller Rotation
Pushing force
Mandrel Blank Force-controlled Metal Spinning
While a non-circular product is being spun, the roller must move forward and backward very rapidly. In Robospin, a linear motor directly drives the roller. The roller can quickly track the contour of the mandrel, and the forming time of the non-circular product is thus reduced. Another method of forming non-circular products is Synchronous Metal Spinning. The radial displacement, x, of the roller is controlled in synchrony with the rotation angle, θ, of the work piece. The trajectory of the contact point between the roller and the work piece creates the desired crosssection shape. This method is especially effective in forming non-circular tubes, since no mandrel is necessary. The combination of synchronous metal spinning and force-controlled metal spinning can easily deal with complex shapes and lowformability materials.
Final cross-section Blank
Forming process
Radial displacement x = x(θ)
θ Rotation Roller Current cross-section
Synchronous Metal Spinning Forming process
■ Other Functions ■ Various helpful functions, which are implemented in conventional metal spinning machines, are also integrated into RoboSpin. - A teaching-playback function using a joystick for PNC spinning (circular products only). - Utility functions for the forming task ... automatic tailstock, blank holder, backup roller, knockout mechanism, etc. Specifications of RoboSpin Size
Width 2875mm × Depth 1820mm × Height 1895mm
X-axis (radial)
Linear Servo Motor rated thrust 4000N
Z-axis (axial)
Servo Motor + Ball Screw rated thrust 10000N
Spindle
Servo Motor + Planetary Gear rated power 7.5kW rated speed 375rpm
Work
Max. diameter 400mm length 350mm
Backup roller
Forming roller
Z-axis
Tailstock
X-axis
Spindle Mandrel Knockout mechanism
Contact Dr. Hirohiko Arai Advanced Manufacturing Research Institute National Institute of Advanced Industrial Science & Technology (AIST) 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 JAPAN phone: +81-29-861-7088 fax: +81-29-861-7098 E-mail：
[email protected] http://staff.aist.go.jp/h.arai/
Blank holder
