Machine tool with worn-detection function for tool

• US 5,921,726 A
• Filed: 04/22/1997
• Issued: 07/13/1999
• Est. Priority Date: 04/23/1996
• Status: Expired due to Term

• Current Assignee: Toshiba Kikai Kabushiki Kaisha (Shibaura Machine Co., Ltd.)
• Original Assignee: Toshiba Kikai Kabushiki Kaisha (Shibaura Machine Co., Ltd.)
• Inventors: Momochi, Takeshi, Nagashima, Kazuo, Shiozaki, Masahito, Fujie, Hideo
• Primary Examiner(s): Pitts, Andrea L.
• Assistant Examiner(s): Bhargava, Adesh
• Application Number:
  US08/837,725
• Time in Patent Office: 812 Days
• Field of Search: 408/6, 408/5, 408/11, 408/10, 364/474.17, 313/798-815, 313/438, 313/650, 73/104
• US Class Current: 408/6
• CPC Class Codes: B23Q 1/70 Stationary or movable members for carrying working-spindles for attachment of tools or work B23Q1/01 takes precedence; designed to be moved by using particular mechanisms B23Q1/44
• CPC Class Codes: B23Q 17/0957 Detection of tool breakage detecting failure of drills B23B49/001
• CPC Class Codes: B23Q 17/0961 by measuring power, current or torque of a motor
• CPC Class Codes: Y10T 408/14 Responsive to condition of Tool or tool-drive

Abstract

A machine with a worn detection function for a tool capable of reliably carrying out a worn detection for a tool. A present consumption power PW1 of a built-in motor 19, driving a main shaft 11, is watched and compared with a reference consumption power PW2, previously defined, by using a load meter 31, an A/D converter 32, a comparator 33 and a processing unit 34, thereby wear on the tool 12 is detected when the consumption power PW1 is larger than the reference consumption power PW2 as a cutting process is advanced. The main shaft 11 is supported by air static-pressure bearings 14 to 18, so that noise created with rotating, which exert an influence upon the consumption-power detected value, is extremely smaller as compared with the conventional antifriction bearing and so on. Thereby allowing delicate fluctuation of the consumption power to be detected, and naturally the worn detection for the tool 12 to be ensured.

Claims

1. A machine tool with a worn detection function for a tool, comprising:

a main shaft attached with the tool and supported by an air static-pressure bearing to be rotated;

a shaft driving motor driving said main shaft to rotate;

a consumption-power detection means for detecting consumption power of said shaft driving motor; and

a worn-detection means for detecting wear on the tool by memorizing a reference consumption power of said shaft driving motor and comparing the reference consumption power with consumption power detected by said consumption-power detection means, wherein said worn-detection means includes a cut-starting detector for detecting the start of a cutting process for a predetermined work piece by using the consumption power obtained from said consumption-power detection means, a reference-value stored area storing the consumption power of said shaft driving motor during the cutting process for the predetermined work piece as time-series values in elapsed-time from the start of the cutting process and outputting the reference consumption power of the time points, an accord controller for fetching the reference consumption power corresponding to the present time from said reference-value stored area, based on the elapsed time from the start of the cutting process, detected by said cut-starting detector, to the present time, and a comparing area for comparing the reference consumption power fetched by said accord controller, with the present consumption power obtained from said consumption-power detection means, said reference-value stored area storing and said accord controller fetching the reference consumption power at predetermined sampling times.

2. The machine tool with the worn detection function for the tool according to claim 1, wherein said reference-value stored area and said accord controller store and fetch the reference consumption power at every predetermined sampling time inputted from the outside.

3. The machine tool with the worn detection function for the tool according to claim 1, wherein said worn-detection means memorize an admissible differential value, inputted from the outside, and determines that the tool is worn when a difference of the consumption power, detected by said consumption-power detection means, and the reference consumption power is larger than the admissible differential value.

4. The machine tool with the worn detection function for the tool according to claim 1, wherein said worn-detection mean;

memorize the consumption power, obtained from said consumption-power detection means, as the reference consumption power when the first cutting process for a predetermined work piece is carried out.

5. The machine tool with the worn detection function for the tool according to claim 1, wherein said worn-detection means memorize the consumption power, obtained from said consumption-power detection means, as the new reference consumption power in each of cutting processes for the predetermined work piece.

6. A machine tool with a worn detection function for a tool, comprising:

a main shaft attached with the tool and supported by an air static-pressure bearing to be rotated;

a shaft driving motor driving said main shaft to rotate;

a consumption-power detection means for detecting consumption power of said shaft driving motor; and

a worn-detection means for memorizing an admissible differential value, inputted from the outside, and a reference consumption power of said shaft driving motor, and determining that the tool is worn when a difference of the reference consumption power and the consumption power, detected by said consumption-power detection means, is larger than the admissible differential value, and wherein said worn-detection means includes a cut-starting detector for detecting the start of a cutting process for a predetermined work piece by using the consumption power obtained from said consumption-power detection means, a reference-value stored area storing the consumption power of said shaft driving motor during the cutting process for the predetermined work piece as time-series values in elapsed-time from the start of the cutting process and outputting the reference consumption power of the time points, an accord controller for fetching the reference consumption power corresponding to the present time from said reference-value stored area, based on the elapsed time from the start of the cutting process, detected by said cut-starting detector, to the present time, and a comparing area for comparing the reference consumption power fetched by said accord controller, with the present consumption power obtained from said consumption-power detection means, said reference-value stored area storing and said accord controller fetching the reference consumption power at predetermined sampling times.

7. A machine tool with a worn detection function for a tool, comprising:

a main shaft attached with the tool and supported by an air static-pressure bearing to be rotated;

a shaft driving motor driving said main shaft to rotate;

a consumption-power detection means for detecting consumption power of said shaft driving motor; and

a worn-detection means for memorizing an admissible differential value, inputted from the outside, and a reference consumption power of said shaft driving motor, and determining that the tool is worn when a difference of the reference consumption power and the consumption power, detected by said consumption-power detection means, is larger than the admissible differential value, the worn-detection means having a cut-starting detector detecting a start of a cutting process for a predetermined work piece by using the consumption obtained from said consumption-power detection means, a reference-value stored area storing the consumption power of said shaft driving motor, during the cutting process for the predetermined work piece, as time-series values in response to elapsed-time from at the start of the cutting process and outputting the reference consumption power of time points, an accord controller fetching the reference consumption power corresponding to the present time from said reference-value stored area on the basis of the elapsed-time from the start of the cutting process, detected by said cut-starting detector, to the present time, and a comparing area comparing the reference consumption power, fetched by said accord controller, with the present consumption power, obtained from said consumption-power detection means, so that said reference-value stored area and said accord controller store and fetch the reference consumption power at every predetermined sampling time inputted from the outside.

8. The machine tool with the worn detection function for the tool according to claim 7, wherein said worn-detection means memorize the consumption power, obtained from said consumption-power detection means, as the reference consumption power when the first cutting process for a predetermined work piece is carried out.

9. The machine tool with the worn detection function for the tool according to claim 7, wherein said worn-detection means memorize the consumption power, obtained from said consumption-power detection means, as the new reference consumption power in each of cutting processes for the predetermined work piece.