Cushion Pad Position and Load Sensing for Double Blank Detection
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Solution Overview
Problem
Existing double blank detection methods for press machines are inaccurate due to low resolution in slide position and press load detection, leading to time-consuming adjustments and unreliable detection of double blanks, especially in heavy and large press machines without die cushion devices.
Innovation Solution
A double blank detecting device that utilizes die cushion position and load signals for accurate detection, employing a position signal acquiring unit and load signal acquiring unit to identify double blanks based on stable and responsive cushion pad position and load signals, with adjustable abnormality identification values for enhanced detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If slide position and press load are detected to identify double blanks, then double blank detection is implemented, but detection accuracy is low due to large change range and low resolution
Solution Approach 1:
The cushion pad serves as an intermediary element between the slide and the workpiece. By detecting the position and load of the cushion pad instead of directly detecting slide position and press load, the system achieves higher measurement precision. The cushion pad amplifies the displacement effect caused by double blanks, making it easier to detect with available sensors.
Solution Approach 2:
The detection function is segmented into two independent measurements: cushion pad position detection and cushion pad load detection. This segmentation allows each measurement to be optimized independently, with the position detection capturing displacement and the load detection capturing force, thereby improving overall detection accuracy compared to direct slide position measurement.
2Reliability
If limit switch is used in die for double blank detection, then mechanical detection is achieved, but detection stability is poor due to machine vibration at excessive state
Solution Approach 1:
The mechanical limit switch detection system is replaced with an electrical sensing system that measures cushion pad position and load. This substitution eliminates the mechanical contact and switching actions that are susceptible to vibration interference, providing more stable and reliable detection under vibrating conditions.
Solution Approach 2:
The cushion pad acts as a mediator that isolates the detection system from the high-vibration environment of the slide and die contact zone. By measuring cushion pad parameters rather than direct die contact parameters, the system achieves more stable measurements despite machine vibration.
3Measurement precision
If fine adjustment is performed for each die to tune limit switch, then detection calibration is achieved, but adjustment time is excessive
Solution Approach 1:
The system performs self-calibration by automatically establishing the relationship between cushion pad position and workpiece thickness during normal operation. The controller stores the detected cushion pad position when a single blank is present as the reference value, eliminating the need for manual fine adjustment of each die while maintaining detection accuracy.
Solution Approach 2:
The system implements automatic feedback-based calibration where the controller continuously monitors cushion pad position and load, compares them against stored reference values, and automatically adjusts detection thresholds. This feedback mechanism replaces manual tuning with automated adaptation, significantly reducing adjustment time.
4Measurement precision
If slide position detection is used for double blank identification, then position-based detection is achieved, but resolution is insufficient for heavy and large press machines
Solution Approach 1:
The detection system is segmented into independent cushion pad position and load measurement components. This segmentation allows the use of high-resolution sensors on the lighter cushion pad assembly rather than requiring high-resolution measurement of the entire heavy slide assembly, thereby achieving sufficient resolution without being constrained by the large size and weight of the press machine.
Data Source
AI summary
The double blank detecting device for a press machine uses a press machine with a die cushion device attached thereto, and automatically and repeatedly forms blank materials one by one. The double blank detecting device includes: a position signal acquiring unit that acquires a die cushion position signal indicating a position of a cushion pad of the die cushion device; a load signal acquiring unit that acquires a die cushion load signal indicating a die cushion load generated in the cushion pad of the die cushion device; and a double blank detecting unit that detects, as a double blank, a state where a plurality of the blank materials are overlapped, based on the die cushion position signal and the die cushion load signal that are acquired.