Servo Die Cushion Control Apparatus Abnormal Force Detection
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Solution Overview
Problem
Conventional die cushion mechanisms using servo-motors face challenges in immediately detecting abnormalities in force production and inappropriate position control, leading to potential malfunctions and safety issues due to malfunctions in force detection or incorrect input commands.
Innovation Solution
A control apparatus for the die cushion mechanism incorporating a servo-motor, featuring a force commanding section, a force detecting section, a force controlling section, and an abnormality preventing section that includes an abnormality judging section, alarm section, and current limiting capabilities to ensure safe and proper force and position control by comparing detected values with predetermined thresholds and adjusting control states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a servo-motor is used as a drive source for the die cushion mechanism, then the response performance of force control is improved, but the ability to immediately detect abnormalities in force production or position control is deteriorated
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the actual force produced by the servo-motor and comparing it with the commanded force value. The abnormality preventing section receives feedback from both the force detecting section (actual force) and the force commanding section (commanded force), and automatically detects abnormalities when discrepancies occur, enabling immediate response to control issues.
2Manufacturing precision
If the control scheme is changed from position control to force control based on collision detection, then the accuracy of press working is improved, but the safety against undetected abnormalities is deteriorated
Solution Approach 1:
The patent applies preliminary action by establishing a safety monitoring system that is active before abnormalities can cause damage. The abnormality preventing section continuously compares commanded force with actual force from the force detecting section, and is prepared to immediately switch control modes or trigger alarms before undetected abnormalities can lead to unsafe conditions or poor work quality.
3Adaptability or versatility
If force control is executed based on predetermined force command values, then the adaptability to different pressing conditions is improved, but the risk of error in inputting force command values is increased
Solution Approach 1:
The system uses feedback to verify force command execution by comparing the commanded force value from the force commanding section with the actual force measured by the force detecting section. The abnormality preventing section monitors this feedback loop and can detect when the actual force deviates from the commanded force, indicating potential input errors or system malfunctions, thereby reducing the risk of harmful effects from incorrect force commands.
Data Source
AI summary
A control apparatus for controlling a die cushion mechanism including a servo-motor as a drive source and producing a force adapted to be applied outside. The control apparatus includes a force commanding section for commanding a force to be produced by the die cushion mechanism; a force detecting section for detecting a force produced by the die cushion mechanism; a force controlling section for executing a force control on the servo-motor, based on a force command value commanded by the force commanding section and a force detected value detected by the force detecting section; and an abnormality preventing section for preventing, in association with a control state of the servo-motor, the die cushion mechanism from producing an abnormal force.