Abstract: A mechanical press shapes parts by driving a ram into a metal sheet to deform it into a desired form. Because this process is widely used-from forming pop cans to shaping car body panels-mechanical presses play a crucial role in global manufacturing. The metal forming industry has recently encountered a shift towards servomotor drivetrains that can electronically alter the ram motion profile. The objective of this research is to develop alternative linkage drivetrain designs that generate prescribed ram motions while maintaining acceptable joint forces. By focusing on a drivetrain linkage, this study leverages the advantages over their servo-driven counterparts, including higher speeds, lower costs, greater precision, and improved energy efficiency. The research evaluates five drivetrain designs under industrial conditions to enhance the dwell phase and achieve the required joint forces. Two of these designs are currently prevalent in the industry, while the remaining three offer potential advancements.
Novel High-Speed Mechanical Press Designs Optimized for Improved Ram Dwell Limited by Joint Force Considerations
Tianze Xu
Advisors: Andrew Murray & David Myszka
Department of Mechanical & Aerospace Engineering
Press Geometries Studied
(a) Knuckle
(b) Knuckle-Ternary
(c) GFBS
(d) GFBS-Ternary
Building upon the crank-driven as a baseline, we explored four alternative drivetrain configurations:
Knuckle: an alternate mechanism used in industry.
Knuckle–Ternary: Incorporates a ternary link to enhance motion flexibility.
GFBS (Geared Five-Bar with Sliding Output): Introduces gear coupling for improved motion control.
GFBS–Ternary: Combines both approaches to achieve the most advanced performance.
Optimization Approach – Desired I/O
Crank Slider
Optimization Approach – Error Calculation
Knuckle-Joint
Forward Kinematic Equations
Input – Output Equation
Fmincon( );
function
Optimization Flow Chart
Optimize Flow Chart
Ram Line
Approach – Force Analysis
Knuckle Force Analysis
Optimize Chat Flow with Force Constraint
Optimization Result
Figure above illustrates the input-output plot generated using the proposed optimization method under varying maximum joint load-force constraints. The horizontal axis represents the angle (driving angle of link a), while the vertical axis denotes the stroke trajectory of the press slider (with 2mm indicating contact with the workpiece). The plot shows that as the allowable maximum force decreases; the dwell correspondingly reduces.
The Input-Output Plot for different max load-force constrain