Servomotor Press Machine Control Device Malfunction Response
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Solution Overview
Problem
Conventional die cushion mechanisms using hydraulic or pneumatic units cannot vary pressure effectively, leading to excessive force increases when a malfunction occurs in either the slide or die cushion, potentially damaging the press machine, as they are controlled separately and lack interconnected control.
Innovation Solution
A control device for a press machine using a servomotor as a drive source, featuring a slide control part and a die cushion control part with detectors and transmitters to detect malfunctions and adjust positions to prevent excessive force by moving the slide or die cushion away from each other when a malfunction is detected, thereby stopping their motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate control devices are used for the slide and die cushion, then each component can be controlled to a predetermined position, but when a malfunction occurs in one component, the other continues moving based on normal position commands causing excessive force increase
Solution Approach 1:
The patent merges the control functions of the slide and die cushion into an integrated control system where the control device receives position commands for both components and coordinates their movements. The control device calculates position commands for the die cushion based on the slide's position command and current positions, ensuring synchronized operation. This integration allows the system to treat malfunctions in one component as signals to adjust the other component's movement, preventing excessive force buildup while maintaining coordinated control.
2Reliability
If the die cushion is stopped immediately upon malfunction detection, then the die cushion safety is improved, but the slide may continue moving causing excess force increase and machine damage
Solution Approach 1:
The patent implements a feedback mechanism where the control device continuously monitors the operational status of both the slide and die cushion. When a malfunction is detected in one component, the control device uses this feedback information to adjust the position commands for the other component. Specifically, the control device calculates modified position commands that account for the malfunctioning component's status, ensuring that the operational component does not move into a position that would cause excessive force. This feedback loop enables coordinated safety responses that protect against both component-specific failures and system-wide damage.
3Device complexity
If hydraulic or pneumatic units are used for the die cushion, then the structure is simple, but the pressure cannot be varied corresponding to the amount of drawing
Solution Approach 1:
The patent replaces the hydraulic or pneumatic drive system with a servomotor-based mechanical drive system. The servomotor receives position commands from the control device and directly drives the die cushion mechanism through a lead screw or similar mechanical transmission. This substitution enables precise control of the die cushion's position and force output by varying the servomotor's rotation angle and speed according to the slide's drawing progress. The mechanical drive system maintains structural simplicity while providing the adaptability to vary pressure corresponding to the amount of drawing, which hydraulic or pneumatic systems cannot achieve.
Data Source
AI summary
A control device for a press machine, by which one of the slide and the die cushion is suitably controlled, when a malfunction occurs in the other, such that the force between the slide and the die cushion does not excessively increase. The control device includes a slide control part for controlling the motion of the slide and a die cushion control part for controlling the motion of the die cushion. A first transmitter transmits an abnormal signal from the die cushion control part to the slide control part when a first detector detects a malfunction of the die cushion. The slide control part is configured to move the slide, when receiving the abnormal signal, such that the slide is away from the position of the die cushion at the time of receiving the abnormal signal by a certain distance and, to stop the slide.