A Microcomputer-Based Quality Control Monitor for a High-Speed Cold-Heading Machine
A variety of small components, particularly fasteners, is produced by cold-heading machines at rates approaching 700 items/min. A problem commonly encountered is the incidence of cracked heads especially in pan-head fasteners with a cruciform-type drive recess. Large batches of fasteners that have defects are rejected during production on the basis of a conventional acceptance sampling scheme. These batches are subsequently 100% inspected which leads to large bottlenecks in production and considerable work in progress. The cracking is believed attributable to randomly occurring defects in the wire feedstock such as piping and surface flaws and attempts to eliminate this problem by preprocess inspection of the material have proved ineffective except in very severe cases. This paper describes the development and operating principles of a microcomputer-based quality monitor which uses information derived from the forming loads applied by the heading machine. The system identifies defective items as they are produced and provides information for automatic rejection before they reach the finished batch. The monitor uses the concept of real-time envelope evaluation, and derives information which not only identifies the production of defectives, but can also be utilized to protect the machine from accidental damage in the event of production problems.
KeywordsWeld Nugget Defective Item Slave Processor Accidental Damage Permissible Deviation
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