Vibration-sensing tool break and touch detector optimized for machining conditions

• US 4,724,524 A
• Filed: 06/12/1985
• Issued: 02/09/1988
• Est. Priority Date: 06/12/1985
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Thomas, Charles E., Lee, Minyoung, Harris, Lawson P., Hayashi, Steven R., Bedard, James F.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Lastova, John R.
• Application Number:
  US06/744,083
• Time in Patent Office: 972 Days
• Field of Search: 364/167, 364/170, 364/474, 364/475, 364/508, 364/157, 364/148, 318/572, 73/104, 73/587, 73/660, 340/680
• US Class Current: 700/175
• CPC Class Codes: B23Q 17/0971 by measuring mechanical vibrations of parts of the machine arrangements for measuring vibrations B23Q17/12
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition
• CPC Class Codes: G05B 2219/37351 Detect vibration, ultrasound

Abstract

A Machine Tool Monitor detects significant cutting tool breakage and the first contact of an advancing tool to a workpiece, and does this by monitoring vibration signals produced by the machining of parts and interpreting patterns in these signals. Information from the part program improves the performance of the detector and optimizes it for the cutting conditions called for by the machine tool control. The analog channel gain of the monitor is adjusted and parameters controlling the digital pattern recognition logic are selected using part program information on machining parameters. The tool touch or tool break detection mode is selected by the part program.

Claims

1. A method of optimizing the performance of a monitor installed on a machine tool which is controlled by a machine tool control having a part program, comprising the steps of:

sensing vibrations resulting from interaction of a cutting tool with a workpiece and from other machine tool noise sources and generating a vibration signal;

preprocessing said signal in an analog channel which has an adjustable gain, attenuates lower frequency machinery noise, and generates an analog waveform representative of the amplitude of vibrations in a chosen band below 100 KHz;

analyzing samples of said analog waveform in a digital processor to detect, by means of pattern recognition logic, signal patterns characteristic of significant tool breakage and light rubbing contact of said tool and workpiece, and generating tool break and tool touch alarms which are sent to said machine tool control; and

adjusting the gain of said analog channel using part program information on machining parameters including workpiece surface speed, feed rate, depth of cut, and workpiece and tool description to optimize operation of said monitor for the cutting conditions called for by said machine tool control.

2. The method of claim 1 further including the step of using said part program information on machining parameters including finish/rough cut description and spindle revolutions per minute, to determine logic parameters controlling break detection logic which is part of said pattern recognition logic.

3. The method of claim 2 further including the step of selecting the tool break or tool touch mode of operation of said monitor from information in said part program.