Tool break detecting method and system preventing false alarms due to rough surfaces

Patent 4849741 Issued on July 18, 1989. Estimated Expiration Date:

January 13, 2008. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Acoustic detection of tool break events in machine tool operations
Patent #: 4636779
Issued on: 01/13/1987
Inventor: Thomas , et al.

Acoustic monitoring of cutting conditions to detect tool break events
Patent #: 4636780
Issued on: 01/13/1987
Inventor: Thomas , et al.

Acoustic tool break detection system and method
Patent #: 4642617
Issued on: 02/10/1987
Inventor: Thomas , et al.

Method and apparatus for discriminating cutting state from non-cutting state in machine tool
Patent #: 4656868
Issued on: 04/14/1987
Inventor: Azuma , et al.

Detector to discriminate between tool break acoustic signatures and spiky noise Patent #: 4707687
Issued on: 11/17/1987
Inventor: Thomas , et al.

Inventor

Thomas, Charles E.

Application

No. 07/143901 filed on 01/13/1988

US Classes:

340/683, Vibration340/680, Machine tool73/104, SURFACE AND CUTTING EDGE TESTING73/660Rotating machinery or device

Examiners

Primary: Swann, III, Glen R.

Attorney, Agent or Firm

International Classes

G05B 19/406 (20060101)
G05B 19/4065 (20060101)

Abstract

Substantial cutting condition changes which occur in intermittent bursts as rough surfaced workpieces are turned generate specific vibration signal signatures known as the runout condition. Either an upper or a lower threshold is set and all mean signal samples are compared with the threshold value. When the mean cutting noise exceeds the upper threshold or stays below the lower threshold for a preset number of signal samples, a tool break alarm is generated. Techniques are given to reduce false alarms on runout during initial rough surface cuts. The system comprises an accelerometer or other sensor whose signal is processed to attenuate lower frequency machinery noise and to detect the signal energy in a band below 100 kHz, then sampled, and the digitized signal samples analyzed by pattern recognition logic.

Other References

Hayashi et al., "Automatic Tool Touch and Breakage Detection in Turning", General Electric Company, Technical Information Series, No. 85 CRD 097, pp. 1-11 (Jun. 1985)