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TECHNICAL PAPERS

A New Type of Controllable Mechanical Press: Motion Control and Experiment Validation

[+] Author and Article Information
W. Z. Guo1

Department of Automation and Computer Aided Engineering,  The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China

K. He, K. Yeung

Department of Automation and Computer Aided Engineering,  The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China

R. Du2

Department of Automation and Computer Aided Engineering,  The Chinese University of Hong Kong, Shatin, NT, Hong Kong, Chinardu@acae.cuhk.edu.hk

1

Currently at the School of Mechanical Engineering, Shanghai Jiaotog University, Shanghai, China.

2

To whom correspondence should be addressed.

J. Manuf. Sci. Eng 127(4), 731-742 (Jul 21, 2004) (12 pages) doi:10.1115/1.1954791 History: Received September 22, 2003; Revised July 21, 2004

This paper is the second part of our study on designing a new type of metal forming press. In the first part of the study (Du, R., and Guo, W. Z., 2003, ASME J. Mech. Des., 125(3), pp. 582–592), a new controllable mechanical press is introduced that consists of a large constant-speed motor (CSM) and a small variable-speed servomotor (VSM). The CSM provides up to 80% of the power while the VSM tunes the motion of the ram. This new design has a number of advantages: it is flexible (i.e., its ram motion is programable), fast (its speed is limited only by the mechanical motion), and energy efficient (the CSM can use a large flywheel to ease the large instantaneous metal forming force). This paper focuses on the motion control and experiment validation. First, the inverse kinematics is presented, which gives the relationship between the ram travel and (i) the input angular displacements, velocities, and accelerations of the two motors. Next, a trajectory-planning method is given. Then, the sensitivity analysis is carried out, which helps to determine the key dimensions of the press and the error compensation scheme. Finally, two experiments are shown to demonstrate that the new press can accomplish different tasks.

Copyright © 2005 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Illustration of the new design

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Figure 2

Effect of the initial angular positions

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Figure 3

Illustration of the boundaries of the ram travel

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Figure 4

The ram travel when the VSM does not run a full cycle: (a) the ram travel never touches the boundary curves and (b) the ram travel is on the boundary curves for a period of time

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Figure 5

Illustration of the via points in trajectory planning. The graph on the left shows the given via points as a function of θ1, in which the top curve (in red) and the bottom curve (in green) are upper and lower boundaries of the ram travel, respectively. The graph on the right shows the corresponding input angular positions in the joint space (θ1,θ2).

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Figure 6

Simulation results of the sensitivity analysis: (a) sensitivity of the structural parameters: red solid line–r1, blue dashed line–r2, purple dotted line–r3, green solid line–r4, and black dashed dotted line–r5; (b) sensitivity of the assembly parameters; red solid line–d1, blue dashed line–d2, and purple dotted line–e; and (c) sensitivity of the motion parameters; red solid line–θ1 and blue dashed line–θ2

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Figure 7

Compensation of the time independent errors by trajectory planning

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Figure 8

Compensation of the motor rotation errors by feedback control

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Figure 15

New press to be built

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Figure 14

Comparison between the simulation and experiment results

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Figure 13

Simulation results for Example 2

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Figure 12

Comparison between the simulation and experiment results

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Figure 10

Control block diagram

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Figure 9

Experiment setup: (a) front view and (b) back view

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Figure 11

Simulation results for Example 1

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