Punching Press Feed Control for Lower Servo Torque Peaks
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Solution Overview
Problem
Servo feeds in modern punching presses require powerful servo drives due to large accelerations and torques needed, leading to increased investment costs and potential material handling restrictions.
Innovation Solution
A method for operating a punch press where the synchronization of the feed movement profile with the crank or eccentric drive is cancelled upon triggering a press stop, allowing the feed movement profile to be completed independently of the drive rotation, reducing the maximum torque requirement for the feed axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the feed movement profile is synchronized with the crank drive rotation angle, then the positioning precision and safety are improved, but the torque requirement and servo drive power increase significantly
Solution Approach 1:
The patent applies dynamics by making the synchronization relationship between feed movement and crank drive rotatable or adjustable. The control unit can dynamically switch between synchronized mode (for positioning precision) and independent mode (for reducing torque requirements), allowing the system to adapt its behavior based on operational requirements rather than being fixed in one mode
Solution Approach 2:
The patent changes the parameter of synchronization by introducing a controllable synchronization state that can be switched on or off. When synchronization is enabled, the feed movement profile follows the crank drive rotation angle for precise positioning. When disabled, the feed can operate independently with reduced torque requirements, thus dynamically adjusting the synchronization parameter to balance precision and power consumption
2Manufacturing precision
If large accelerations are provided on the feed axes to maintain synchronization, then the feed positioning accuracy is improved, but the torque requirement and investment costs increase
Solution Approach 1:
The system dynamically adjusts the acceleration profile based on whether synchronization is active. During synchronized operation, accelerations are coordinated with the crank drive cycle to maintain positioning accuracy. During independent operation, the acceleration profile can be optimized for the specific feed task without needing to match crank drive dynamics, reducing the required servo drive power and investment costs
Solution Approach 2:
The patent changes the acceleration parameter by allowing it to be independently controlled when synchronization is disabled. This enables the use of lower acceleration values that are sufficient for the feed task without needing to provide the large accelerations required for tight synchronization, thereby reducing torque requirements and equipment investment costs while maintaining acceptable positioning accuracy
3Reliability
If the feed length is extended to monitor target position at every point, then the safety is improved, but the braking angle and press cycle time increase
Solution Approach 1:
The patent applies dynamics by making the feed length and monitoring points adaptable based on the operational phase. During synchronized operation, the feed length can be extended with monitoring at multiple points to ensure safety. During independent operation after synchronization cancellation, the feed length can be optimized for the specific task without requiring extended monitoring, thus reducing the braking angle and press cycle time while maintaining safety through the independent control capability
Data Source
AI summary
A method for operating a punching press with a press plunger driven by a crank drive, which operates in a machining zone of the punching press against a stationary clamping plate, and with a servo feed apparatus for intermittently feeding a band of material to be processed to the machining zone. In punching mode, the press plunger is moved back and forth by the crank drive between a first movement dead point (0°), in which the press plunger is at maximum distance from the clamping plate, and a second movement dead point (180°), in which the press plunger is at minimum distance from the clamping plate. In the process, the material band is pushed by the servo feed apparatus around the first movement dead point (0°) in a first rotation angle window (3) of the crank drive by a certain length into the machining zone and processed in a second rotation angle window during the feed pauses. The feed movement of the servo feed drive takes place according to an electronically defined feed movement profile (5), which is followed in the first rotation angle window (3) in an electronically synchronized manner to the rotation of the crank drive (4). When a press stop (6) is triggered in the first rotation angle window (3), the synchronization of the feed movement profile (5) with the rotation of the crank drive (4) is canceled and the feed movement profile (5) is moved to the end independently of the rotation of the crank drive (4). This mode of operation reduces the maximum torque requirement of the feed axes for servo feeds operated angularly synchronously with the crank drive of the press plunger, so that smaller and therefore more cost-effective servo drives can be used or more load can be moved with a given servo drive.