Variable Speed Electric Motor Control for Mechanical Press Cycle Optimization
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Solution Overview
Problem
Traditional mechanical presses require complex and time-consuming adjustments for die changes and maintenance, with fixed production cycles that interrupt production for optimization, and have limitations in force transmission and peak power consumption.
Innovation Solution
A method for controlling the speed of an electric drive motor in a mechanical press to vary throughout the production cycle, allowing for dynamic control of the press cycle beyond 360 degrees, eliminating the need for a flywheel and enabling reduced peak power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional flywheel-driven mechanical press is used, then the press can maintain a fixed production cycle with consistent pressing speed, but the production cycle time cannot be optimized without interrupting production and adjusting mechanical components
Solution Approach 1:
The patent applies dynamics by replacing the fixed-speed flywheel drive with a variable speed electric motor that can dynamically adjust its rotational speed throughout the production cycle. This allows the press to accelerate during non-pressing phases and maintain optimal speed during pressing operations, optimizing production cycle time without requiring mechanical adjustments. The motor speed can be programmatically controlled to match the optimal speed profile for each phase of the cycle.
Solution Approach 2:
The patent implements parameter changes by varying the motor speed parameter throughout the production cycle rather than maintaining a constant speed. The motor can operate at different speeds during different phases: higher speeds during acceleration and non-pressing periods, and controlled speeds during the pressing phase. This dynamic parameter adjustment eliminates the need to interrupt production for mechanical reconfiguration.
2Productivity
If the motor speed is increased to reduce production cycle time, then productivity improves, but peak power consumption increases
Solution Approach 1:
The patent applies periodic action by implementing a cyclical speed profile where the motor operates at high speed during non-pressing phases and reduces speed during the pressing phase. This periodic variation in speed allows the system to maintain high overall productivity while managing peak power consumption, as the motor does not need to sustain maximum speed throughout the entire cycle. The high-speed periods are interspersed with lower-speed periods, creating a rhythmic operation pattern.
Solution Approach 2:
The patent uses dynamics to dynamically adjust motor speed based on the operational phase. The motor accelerates rapidly during non-pressing phases to minimize cycle time, then smoothly transitions to the appropriate speed for the pressing operation. This dynamic speed control allows the system to achieve short production cycle times while avoiding sustained peak power consumption, as the motor only operates at high power levels during necessary acceleration phases rather than continuously.
3Adaptability or versatility
If a ball-screw drive is used to eliminate the flywheel, then the peak power requirement increases, but the press can achieve programmable slide motion
Solution Approach 1:
The patent applies mechanics substitution by replacing the ball-screw mechanical drive with a direct motor-driven approach. Instead of using a ball-screw mechanism that converts rotational motion to linear motion through mechanical threads, the invention uses the motor's rotational output directly to drive the press slide through a simpler transmission system. This substitution eliminates the mechanical complexity of the ball-screw while managing peak power requirements through intelligent speed control.
4Productivity
If mechanical braking is used to bring the press to a standstill, then the press can complete its cycle, but mechanical wear and maintenance requirements increase
Solution Approach 1:
The patent applies mechanics substitution by replacing the mechanical braking system with an electrical braking solution. Instead of using mechanical brake pads and drums that create friction and wear, the invention uses the electric motor's electrical control capabilities to decelerate and stop the press slide. The motor can be controlled to reverse torque or apply electrical braking forces, bringing the press to a standstill without mechanical contact and wear. This eliminates the need for brake maintenance while ensuring complete cycle completion.
Data Source
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AI summary
A method for operating a mechanical press comprising at least one electric drive motor (20), a drive control means for controlling at least one said motor, a ram (23), a mechanical means (27, 25) for translating rotational motion of the at least one said motor to linear motion of said ram in a first rotation direction, into a linear motion of said ram arranged to be lowered and raised along a linear path (S) for operating said press to carry out a press cycle including a pressing part and one or more non-pressing parts of said press cycle, and by providing a control output to said drive control means such that the speed (WM) of the at least one said drive motor is varied during at least one said pressing or non-pressing part of a said press cycle. The press may be reversed between production cycles. A press and system including a such press are also described.