# US 6,202,002 B1 · Automatic monitoring of tool status

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- Number: US 6,202,002 B1
- Document ID: US6202002B1
- Status: Granted
- Kind: B1
- Application number: 09/101,237
- Filed: 1998-09-02
- Granted: 2001-03-13
- Earliest claimed: 1996-01-03
- Assignees: Omat Ltd.
- Inventors: Boris Fainstein; Eduard Tabachnik; Mark Zuckerman; Igor Rubashkin
- Web page: https://patentgrep.com/patent/US6202002B1

## CPC

- G05B 19/4065: Monitoring tool breakage, life or condition
- B23Q 17/0957: {Detection of tool breakage (detecting failure of drills B23B49/001)}
- B23Q 17/0961: {by measuring power, current or torque of a motor}
- G05B 2219/37258: Calculate wear from workpiece and tool material, machining operations
- G05B 2219/37344: Torque, thrust, twist, machining force measurement
- G05B 2219/49078: Control of feed only
- G05B 2219/49099: Cutting force, torque
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)
- B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT

## Abstract

Automatic monitoring system and method for providing an instantaneous tool status indication for a stock removal cutter when cutting workpieces in accordance with a given machining operation for which a substantially new stock removal cutter of the same type has a reference average tool wear coefficient R0. The system includes a torque monitor (7) for measuring a main drive cutting torque M during the cutting of an ith successive workpiece. Coupled to the torque monitor (7), is an instantaneous tool wear coefficient processor (13) for calculating a plurality of instantaneous tool wear coefficients r(j) during the cutting of the ith successive workpiece. Coupled to the instantaneous tool wear coefficient processor (13) is an average tool wear coefficient processor (14) for calculating an average tool wear coefficient R(i) from the plurality of instantaneous tool wear coefficient r(j) And finally, coupled to the average tool wear coefficient processor (14) is a tool wear coefficient comparator (15) for comparing each average tool wear coefficient R(i) to the reference average tool wear coefficient R0 to provide an instantaneous tool status indication for the stock removal cutter for each ith successive workpiece.

## Claims

### Claim 1

A system for automatically monitoring tool status so as to provide an instantaneous tool status indication for a stock removal cutter cutting identical workpieces in accordance with a given machining operation for which a substantially new stock removal cutter of the same type has a reference average tool wear coefficient R0, the system comprising:
(a) means for determining a main drive cutting torque M during the cutting of an ith successive workpiece;
(b) an instantaneous tool wear coefficient processor for calculating a plurality of instantaneous tool wear coefficients r(j) for the stock removal cutter during the cutting of said ith workpiece;
(c) an averace tool wear coefficient processor for calculating an average tool coefficient R(i) for the stock removal cutter from said plurality of instantaneous tool wear coefficients r(j); and
(d) a tool wear coefficient comparator for comparing said average tool wear coefficient R(i) to the reference average tool wear coefficient R0 to provide an instantaneous tool status indication for the stock removal cutter after cutting each ith successive workpiece;
characterized in that
said instantaneous tool wear coefficient processor calculates an instantaneous tool wear coefficient r(j) in accordance with the general relationship: M(j)=A0F(j)αr(j)βwherein F is the instantaneous feed rate of the relative movement between the stock removal cutter and a workpiece and A0, α and β are coefficients dependent on the stock removal cutter cum workpiece material combination.

### Claim 2 (depends on 1)

The system according to claim 1, wherein said instantaneous tool wear coefficient processor calculates an instantaneous tool wear coefficient r(j) in accordance with the general relationship: M(j)=A0FZ(j)αr(j)βfor when the stock removal cutter is a milling cutter and Fz is the feed per tooth of the milling cutter.

### Claim 3

A method for automatically monitoring tool status so as to provide an instantaneous tool status indication for a stock removal cutter cutting identical workpieces in accordance with a given machining operation for which a substantially new stock removal cutter of the same type has a reference average tool wear coefficient R0. the method comprisina the steps of.
(a) determining a main drive cutting torque M during the cutting of an ith successive workpiece;
(b) calculating a plurality of instantaneous tool wear coefficients r(j) for the stock removal cutter during the cutting of the ith successive workpiece.
(c) calculating an average tool wear coefficient R(i) for the stock removal cutter from said plurality of instantaneous tool wear coefficients r(j); and
(d) comparing said average tool wear coefficient R(i) to the reference average tool wear coefficient R0 to provide an instantaneous tool status indication for the stock removal cutter after cutting each ith successive workpiece;
characterized in that
step (b) includes calculating an instantaneous tool wear coefficient r(j) in accordance with the general relationship: M(j)=A0F(j)αr(j)βwherein F is the instantaneous feed rate of the relative movement between the stock removal cutter and a workpiece and A0, α and β are coefficients dependent on the stock removal cutter cum workpiece material combination.

### Claim 4 (depends on 3)

The method according to claim 3, wherein step (b) includes calculating an instantaneous tool wear coefficient r(j) in accordance with the general relationship: M(j)=A0Fzαr(j)βfor when the stock removal cutter is a milling cutter and Fz is the feed per tooth of the milling cutter.