Load monitoring system for progressive dies
First Claim
1. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal over a substantial portion of at least one operating cycle, and peak finding means responsive to the time series of numerical load values for automatically indicating which of the numerical load values within an individual operating cycle represent at least two different peak loads applied to said member within said individual operating cycle in comparison to adjacent numerical load values within said individual operating cycle.
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Abstract
A press control system monitors and is responsive to the loads associated with individual die stations in a progressive die. The system detects chipped, dull, or excessively loaded portions of the progressive die and provides automatic quality monitoring of the parts produced by the press. The system provides a display of press load as a function of time scaled by the speed of the press. The press load as a function of time is automatically analyzed to determine and display the number of die stations and the peak loads associated with each die station in the progressive die. The peak loads are compared to limit values that depend in part on the past history of the press in order to monitor the condition of the progressive die and if necessary to shut down the press. The number and quality of parts produced by the press are also determined from the peak loads. Gradual wear of the die is monitored to determined when sharpening is required. To detect anomalies at any phase in the press cycle, the press load is compared between successive cycles. A master/slave computer system is disclosed for monitoring and controlling multiple presses.
97 Citations
40 Claims
- 1. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal over a substantial portion of at least one operating cycle, and peak finding means responsive to the time series of numerical load values for automatically indicating which of the numerical load values within an individual operating cycle represent at least two different peak loads applied to said member within said individual operating cycle in comparison to adjacent numerical load values within said individual operating cycle.
- 5. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal, peak finding means responsive to the time series of numerical load values for automatically indicating which of the numerical load values represent peak loads cyclically applied to said member, resolver means for indicating individual cycles of the loads applied to said member, and automatic means responsive to the indication of individual cycles for associating the numerical load values representing peak loads with their order of occurrence within individual cycles, graphing means for graphically displaying the time series of numerical load values starting at approximately a predetermined phase of an individual cycle indicated by the resolver means, and annotating means for automatically labeling the peaks on the graph with their respective load values representing peak loads.
- 7. A system for monitoring loads that are cyclically applied to a force carrying member comprising load transducer means mounted on said force carrying member for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal, resolver means for indicating individual cycles of the loads applied to said member, graphing means for graphically displaying the time series of numerical load values starting at approximately a predetermined phase of an individual cycle indicated by the cycle indicating means, and speed determining means, responsive to the indication of the cycle indicating means, for indicating the frequency of the cycles of the loads applied to said force carrying member, wherein the graphing means has automatic means for adjusting the time scale of the graphical display in response to the indication of the speed determining means.
- 9. A system for monitoring loads that are cyclically applied to a force carrying member in a press fitted with a progressive die having a plurality of die stations, each die station being adapted to create respective loads applied to the force carrying member during each load cycle, said system comprising, in combination, a load transducer means for generating an electrical signal indicating the load applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal, peak finding means responsive to the time series of numerical load values for automatically indicating which of the numerical load values represent peak loads cyclically applied to said load member, means for periodically generating a trigger signal at approximately a predetermined phase in the load cycle, and means for automatically associating the numerical load values representing peak loads with corresponding ones of the die stations by sequentially associating the peak loads occurring after the most recent trigger signal with the die stations.
- 20. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal, means responsive to the time series of numerical load values for determining at least one peak load for each individual cycle, and means for comparing the peak loads to at least one predetermined threshold value to generate a control signal, wherein said means for comparing generates a press control signal by comparing an average of said peak loads for successive cycles to said predetermined threshold value.
- 26. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the stress applied to said member, analog-to-digital converter means for generating a time series of numerical load values representative of said electrical signal, resolver means for indicating individual cycles of the loads that are applied to said member, means responsive to the time series of numerical load values and the resolver means for determining at least one peak load for each individual cycle, and means for comparing the peak loads to a set of predetermined threshold values to generate a control signal, wherein said set of threshold values includes a high limit threshold, a low limit threshold, a high material threshold and a low material threshold, and wherein said means for comparing generates said control signal to stop the application of said loads when any one of said peak loads is substantially outside of the range between the high and low limit thresholds, and when an average of said peak loads for successive cycles is substantially outside of the range between the high and low material thresholds.
- 30. A system for monitoring loads that are cyclically applied to a force carrying member comprising a load transducer means for generating an electrical signal indicating the force applied to said member, resolver means for indicating individual cycles of the loads applied to said member and also indicating phase points over at least a substantial part of the cycle of load application, analog-to-digital converter means for generating respective numerical load values representative of the value of said electrical signal at said phase points for successive cycles of load application, and means for comparing the numerical load values for the same phase points between at least two successive cycles of load application.
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39. A system for the monitoring and control of a plurality of machines for cyclically applying force, said system comprising:
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for each machine, a load transducer for generating an electrical load signal indicating the force carried by a force carrying member of said machine, resolver means for generating an electrical signal indicating the phase of the force application cycle, a slave microcomputer with an analog-to-digital converter and input/output circuits for digitizing the load signal, said slave microcomputer executing a procedure for storing the digitized values in random access memory, finding peak values of the load signal, comparing the peak values to at least one predetermined threshold value, and generating a control signal to stop the respective machine from cyclically applying said force when the peak values substantially reach said threshold value; said system further comprising a master microcomputer including means for graphing, storing, and tabulating data, wherein said master microcomputer is linked via a digital data link to said slave microcomputer and said master and slave microcomputers execute procedure to permit an operator at the master microcomputer to request and obtain from a selected slave microcomputer selected digitized values of the load signal for a respective one of the machines, and to obtain the peak values found by a selected slave microcomputer. - View Dependent Claims (40)
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Specification