Browse Prior Art Database

Time-Delay Interlock Circuit for Stepper Motors in Manufacturing Equipment

IP.com Disclosure Number: IPCOM000113451D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Singletary, A: AUTHOR

Abstract

Tools and equipment designed for internal use within IBM must comply with the terms of an internal safety document which details the rules, codes and standards necessary to ensure equipment safety and consistency, including equipment safety interlocks. These interlocks are mechanical or electrical systems which prevent personnel operating the equipment from coming into contact with potential hazards. The described invention relates to interlocks which are intended to deactivate moving mechanical systems.

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This is the abbreviated version, containing approximately 79% of the total text.

Time-Delay Interlock Circuit for Stepper Motors in Manufacturing
Equipment

      Tools and equipment designed for internal use within IBM must
comply with the terms of an internal safety document which details
the rules, codes and standards necessary to ensure equipment safety
and consistency, including equipment safety interlocks.  These
interlocks are mechanical or electrical systems which prevent
personnel operating the equipment from coming into contact with
potential hazards.  The described invention relates to interlocks
which are intended to deactivate moving mechanical systems.

      Of particular interest is the safety rule which states
"Programmed machine controls shall not be used for safety
interlocks".  This requirement may be very difficult to satisfy in
modern automated equipment, as most significant features are
controlled by programmable microprocessors.  The disclosed method and
apparatus allow a graceful shutdown via the programmable machine
controls while still complying with all of the standard safety
procedures.

      The solution is accomplished through the use of a time delay
circuit.  When a potentially hazardous situations occurs, an open
interlock switch triggers a time delay relay and simultaneously
generates a signal to the machine controller.  During the delay
period, the moving elements may be decelerated and placed in a safe
state by the machine controller.  At the end of the delay period, a
true hardware interlock is acc...