Signal processing system and signal processing method for cutting tool with abrasion sensor

• US 6,556,925 B1
• Filed: 08/29/2000
• Issued: 04/29/2003
• Est. Priority Date: 11/30/1999
• Status: Expired due to Fees

• Current Assignee: Koji Kajimura, Kyocera Corporation
• Original Assignee: Kajimura Koji, Kyocera Corporation
• Inventors: Nagato, Yoshio, Ryabov, Oleg, Mori, Kazuo
• Primary Examiner(s): Nghiem, Michael
• Assistant Examiner(s): LAU, TUNG S
• Application Number:
  US09/650,951
• Time in Patent Office: 973 Days
• Field of Search: 702/34, 702/81, 304/511, 139/449, 340/453, 364/726, 364/575, 180/103, 382/152
• US Class Current: 702/34
• CPC Class Codes: B23B 27/145 characterised by having a special shape
• CPC Class Codes: B23Q 17/0952 during machining
• CPC Class Codes: G01N 3/56 Investigating resistance to wear or abrasion
• CPC Class Codes: G01N 3/58 Investigating machinability by cutting tools; Investigating the cutting ability of tools

Abstract

For determination of the expiration of the life of a cutting tool on the basis of a resistance signal from sensor lines, a true signal component indicative of the abrasion of the sensor lines should be extracted from the resistance signal. In a signal processing method according to the present invention, an output of an abrasion sensor is sampled in a predetermined sampling cycle (Step S1), and then the sampled data is passed through a median filter for elimination of a noise therefrom (Step S2). Further, the noise-free data is passed through a separation filter (Step S3). By the separation filter, reduction data having a time-serially reduced in value is separated and eliminated from the noise-free data. As a result, true data indicative of a change in the resistance of the sensor is obtained. The true data is subjected to a counter function process (Step S4) thereby to determine how many sensor lines have been cut off by the abrasion. The expiration of the life of the cutting tool is detected when the number of the cut-off sensor lines reaches a predetermined number (Step S5).

Claims

1. A signal processing system for a cutting tool having an abrasion sensor provided on a cutting edge thereof for detecting abrasion and breakage thereof occurring due to a cutting operation, the signal processing system comprising:

means for sampling an output of the abrasion sensor in a predetermined sampling cycle to obtain measurement data;

noise eliminating means for eliminating a noise from the obtained measurement data;

reduction data separating means for separating reduction data having a time-serially reduced in value from the noise-free data; and

life expiration determining means for determining an abrasion degree and breakage of the cutting tool on the basis of process data obtained by the separation of the reduction data.

2. A signal processing system as set forth in claim 1, wherein the noise eliminating means comprises median process means for outputting a median of a predetermined number of sampled group data.

3. A signal processing system as set forth in claim 1,

wherein the abrasion sensor comprises a plurality of sensor lines extending parallel to each other along a cutting ridge of the cutting tool,

wherein the life expiration determining means determines the abrasion degree and breakage of the cutting tool by relating the process data to the number of the sensor lines.

4. A signal processing system as set forth in claim 3, wherein the life expiration determining means determines an initial resistance value of the plurality of sensor lines on the basis of an initial value of the process data, then determines a resistance threshold which is increased in response to cut-off of each of the sensor lines, and provides an output whenever a value of the process data exceeds the resistance threshold to indicate that the number of the cut-off sensor lines is increased.

5. A signal processing system as set forth in claim 2,

wherein the abrasion sensor comprises a plurality of sensor lines extending parallel to each other along a cutting ridge of the cutting tool,

wherein the life expiration determining means determines the abrasion degree and breakage of the cutting tool by relating the process data to the number of the sensor lines.

6. A signal processing system as set forth in claim 5, wherein the life expiration determining means determines an initial resistance value of the plurality of sensor lines on the basis of an initial value of the process data, then determines a resistance threshold which is increased in response to cut-off of each of the sensor lines, and provides an output whenever a value of the process data exceeds the resistance threshold to indicate that the number of the cut-off sensor lines is increased.

7. A signal processing system as set forth in claim 1, wherein the cutting tool comprises a throw-away tip provided with the abrasion sensor and a holder for holding the throw-away tip, and the abrasion sensor is capable of detecting the abrasion degree and breakage of the throw-away tip.

8. A signal processing method for a cutting tool having an abrasion sensor provided on a cutting edge thereof for detecting abrasion and breakage thereof occurring due to a cutting operation, the signal processing method comprising the steps of:

sampling an output of the abrasion sensor in a predetermined sampling cycle;

eliminating a noise from the sampled data;

separating reduction data having a time-serially reduced in value from the noise-free data; and

determining an abrasion degree and breakage of the cutting tool on the basis of process data which is obtained by the separation of the reduction data and is free from time-serial reduction in value.

9. A method as set forth in claim 8,

wherein the abrasion sensor comprises a plurality of sensor lines extending parallel to each other along a cutting ridge of the cutting tool,

wherein the process data has a value which increases time-serially stepwise by increments associated with the number of the sensor lines.