Metal cutting tool wear indicator method and system

• US 5,266,929 A
• Filed: 05/26/1992
• Issued: 11/30/1993
• Est. Priority Date: 05/26/1992
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Carmichael, Jerry H., Diei, Edward N.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US07/888,065
• Time in Patent Office: 553 Days
• Field of Search: 340/680, 364/551.02, 73/104, 73/660
• US Class Current: 340/680
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G05B 19/4065 Monitoring tool breakage, life or condition

Abstract

In a metal cutting tool wear indicator system, a ratio of an estimated ultrasonic emission signal from a metal cutting process to a measured ultrasonic emission signal, e.g. UE/UE is utilized in place of a prior ratio of horsepower to ultrasonic emission, e.g. HP/UE, together with a continuous revision of the estimator during the cutting process.

Claims

1. A method of determining metal cutting tool wear in a metal cutting process comprising

(a) deriving an ultrasonic emission electrical signal, ue, from said cutting process,

(b) processing said ue signal to derive a mean average signal, ue, therefrom,

(c) deriving a horsepower electrical signal, hp, from said cutting process,

(d) processing said hp signal to derive a mean average hp signal, hp, therefrom,

(e) programming an electrical signal processing calculator to calculate a quadratic function of said hp to determine an estimated mean average of said ue signal, ue, for said cutting process,

(f) processing said ue and ue signals in an adjustable ratio processor to determine a ue/ue value correlated to cutting tool wear.

2. The invention as recited in claim 1 wherein said adjustable ratio processor includes signal generating means activated when said ratio reaches a predetermined and time related value.

3. The invention as recited in claim 1 wherein said ue signal is derived from a ue signal processed through a separate processing path comprising a Hilbert transform filter to remove spikes and through one of a pair of matched synchronous filters to provide a mean average ue signal, ue, corrected for rotational variance.

4. The invention as recited in claim 3 wherein said hp signal is derived from an hp signal passed through a separate process path comprising a Tare filter and the other of said matched synchronous filters to provide a mean average hp signal, hp.

5. A method of determining metal cutting tool wear comprising

(a) deriving an electrical hp signal from said cutting tool representative of the horsepower being applied to said tool during its metal cutting process,

(b) deriving an electrical ue signal from said cutting tool corresponding to the ultrasonic emission from said tool--during its metal cutting process;

(c) passing said ue signal through a processing path having electrical signal components including one of a matched pair of synchronous filters which provide a mean average ue signal, ue, for said process,

(d) passing said hp signal through a separate processing path having electrical signal processing components therein including the other one of said matched pair of synchronous filters to provide a mean average hp signal, hp,

(e) passing said hp signal into a quadratic function processor and ue estimator correlated to the quadratic function a(hp)² +b(hp)+c to determine an estimated mean average ue, ue, as an output signal,

(f) passing said hp signal and said ue signal into a coefficient calculator to determine the quadratic coefficient b as an estimated b,b --b--

(g) continuously passing said estimated coefficient b signal to said quadratic function and ue estimator to continuously calculate said estimated mean average ue, ue, for the cutting process,

(h) passing said ue signal and said ue signal to a further coefficient calculator to determine the quadratic coefficient c as an estimated c, c, from the expression c=ue-ue, said c being an input signal to said quadratic function processor and ue estimator,

(i) passing said ue signal and said ue signal into an adjustable ratio processor to determine a ratio value from the ratio ue/ue which indicates tool wear.

6. The invention as recited in claim 5 wherein said further coefficient c calculator interconnects said paths to receive said ue signal from one of said synchronous filters and said ue signal from said quadratic function processor and ue estimator.

7. The invention as recited in claim 5 wherein said coefficient --b-- calculator interconnects said separate paths and said matched pair of synchronous filters to continuously provide a calculated ratio of ue/hp as the --b-- coefficient of said quadratic function.

8. The invention as recited in claim 5 wherein a quadratic coefficient calculator interconnects said one synchronous filter and said quadratic estimator and their output signals to continuously determine the difference between the mean average ue and estimated average ue as the coefficient --c-- of said quadratic function.

9. The invention as recited in claim 5 wherein said coefficient calculators are adapted to continuously revise said coefficients during a metal cutting process.

10. The invention as recited in claim 5 wherein said adjustable ratio processor incorporates tool wear signal means with an adjustable time interval for said signal means so that said tool wear ratio value may be time adjusted to persist for a predetermined period of time to activate said signal means.