Method and apparatus of sequential control for safety for machine tools

• US 4,725,943 A
• Filed: 07/05/1985
• Issued: 02/16/1988
• Est. Priority Date: 07/09/1984
• Status: Expired due to Term

• Current Assignee: Amada Company Limited
• Original Assignee: Amada Company Limited
• Inventors: Kuriyama, Haruhiko, Anjo, Toshiaki
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): MACDONALD, ALLEN R
• Application Number:
  US06/751,856
• Time in Patent Office: 956 Days
• Field of Search: 364/184, 364/185, 364/186, 364/187, 364/474, 364/475, 371/62, 318/626
• US Class Current: 700/79
• CPC Class Codes: G05B 19/4063 Monitoring general control system G05B19/4062 takes precedence

Abstract

A method and apparatus for safety control for a numerically controlled machine tool, including outputting a control signal to the machine tool based upon a code signal received from a numerical control means; outputting a completion signal to the numerical control means when an operation completion signal is received from the machine tool; and outputting a stop signal to the means to stop the machine tool if no operation completion signal is received within a predetermined time.

Claims

1. A method for safety control for sequential control operation of a machine tool by a numerical control means acting in cooperation with a sequencer means to prevent unsafe operation of said machine tool, comprising the steps of:

generating a code signal by said numerical control means;

applying said code signal to said sequencer means;

outputting a control signal from said sequencer means to the machine tool by a code operator in response to the code signal generated by the numerical control means;

outputting a completion signal to said numerical control means by said code operator to continue sequential control operation of said machine tool when an operation completion signal is outputted by the machine tool; and

outputting a stop signal from said sequencer means to the numerical control means by a timer means to stop said numerical control means if no operation completion signal is outputted by the machine tool within a predetermined time.

2. A method for safety control according to claim 1, further comprising the steps of:

activating said timer means in response to the code signal; and

deactivating the timer means in response to the operation completion signal in the predetermined time during which the operation completion signal is to be outputted by the machine tool.

3. An apparatus for safety control for sequential control operation of a machine tool to prevent unsafe operation of said machine tool, comprising:

numerical control means for supplying a control signal for operation of the machine tool;

sequencer means for receiving the control signal supplied by said numerical control means and controlling sequential operation of the machine tool, said sequencer means including;

means for outputting the control signal to the machine tool in response to a code signal outputted by the numerical control means;

means for outputting a completion signal to the numerical control means in response to an operation completion signal outputted by the machine tool to continue sequential control operation;

timer means activated in response to the code signal outputted by said numerical control means and deactivated in response to the operation completion signal from the machine tool, for outputting a stop signal to said numerical control means to interrupt the unsafe operation of the machine tool only when said timer means is not deactivated in response to the operation completion signal within a predetermined time.

4. An apparatus for safety control for sequential control operation of a machine tool by numerical control means to prevent unsafe operation of said machine tool, which machine tool outputs an operation completion signal upon completion of the sequential operation, comprising:

sequencer means for receiving a code signal for operation of the machine tool supplied by said numerical control means, said sequencer means including;

a code decoder which decodes the code signal outputted by the numerical control means;

a code operator which outputs a control signal according to the code signal to the machine tool in response to the code signal decoded by the code decoder and outputs a completion signal to the numerical control means in response to the operation completion signal outputted by the machine tool; and

watch dog timer means which is activated in response to the code signal decoded by the code decoder and is deactivated in response to the operation completion signal outputted by the machine tool, for ouputting a stop signal to said numerical control means to interrupt the unsafe operation of the machine tool only when said watch dog timer means is not deactivated in response to the operation completion signal within a predetermined time.