Thread cutting machine with synchronized feed and rotation motors

• US 4,879,660 A
• Filed: 03/28/1988
• Issued: 11/07/1989
• Est. Priority Date: 03/31/1987
• Status: Expired due to Term

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Asakura, Koichi, Matsumoto, Takenori, Demura, Makoto
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Kulbaski, James J.
• Application Number:
  US07/174,508
• Time in Patent Office: 589 Days
• Field of Search: 364/474.15, 364/474.3, 408/9, 408/10, 318/39, 318/571
• US Class Current: 700/173
• CPC Class Codes: G05B 19/186 Generation of screw- or gearlike surfaces
• CPC Class Codes: G05B 2219/42186 Master slave, motion proportional to axis
• CPC Class Codes: G05B 2219/43006 Acceleration, deceleration control
• CPC Class Codes: G05B 2219/45216 Tapping
• CPC Class Codes: Y10T 408/165 to control Tool rotation
• CPC Class Codes: Y10T 408/17 to control infeed

Abstract

A thread cutting machine is provided with a control system in which, according to one aspect, the rotation of the spindle is controlled in the synchronous manner following up the feed amount of the spindle head and the rotation instruction is computed in accordance with the feed deviation, In another aspect, the feed of the spindle head is controlled in the synchronous manner following up the rotation of the spindle and the feed instruction is computed in accordance with the rotation deviation. In a further aspect, the rotation instruction is operated in accordance with the feed speed and the feed acceleration. In still a further aspect, the feed instruction is computed in accordance with the rotation speed and the rotation acceleration. In the preferred embodiments disclosed herein, the synchronism between the rotation of the spindle and the feed of the spindle head can be remarkably improved with various control modes, thus achieving the high speed thread cutting working with high accuracy.

Claims

1. In a thread cutting machine including a spindle for holding a thread cutting tool, a spindle head for supporting said spindle, a spindle motor for rotating said spindle, a feed motor for driving said spindle head, a detector for detecting a rotating position of said spindle, and a detector for detecting a feed position and a feed amount of said spindle head, and wherein said thread cutting is conducted under synchronous driving operation of said spindle motor and said feed motor, said thread cutting machine comprising:

means for computing a feed deviation between a feed instruction and a feed position of said spindle head detected by the feed position detector;

means operatively connected to said feed deviation computing means for driving the feed motor in accordance with the feed deviation;

means operatively connected to said feed deviation computing means for computing a rotation instruction corresponding to the feed deviation on the basis of a thread pitch;

means operatively connected to said feed position detector for computing a rotation correction value corresponding to the detected feed amount of the spindle head on the basis of the thread pitch;

means operatively connected to said rotation correction value computing means and said spindle rotating position detector for computing a rotation deviation between said rotation correction value and the rotation position of said spindle;

means operatively connected to said rotation deviation computing means for correcting the rotation instruction on the basis of said rotation deviation and

means operatively connected to said correcting means for driving said spindle motor in accordance with the corrected rotation instruction.

2. In a thread cutting machine including a spindle for holding a thread cutting tool, a spindle head for supporting said spindle, a spindle motor for rotating said spindle, a feed motor for driving said spindle head, a detector for detecting a rotating position of said spindle, a detector for detecting a feed position and a feed amount of said spindle head, and wherein said thread cutting is conducted under synchronous driving operation of said spindle motor and said feed motor, said thread cutting machine comprising:

means for computing a rotation deviation between a rotation instruction and a rotating position of said spindle detected by the rotating position detector;

means operatively connected to said rotation deviation computing means for driving said spindle motor for rotating said spindle in accordance with the rotation deviation;

means operatively connected to said rotation deviation computing means for computing a feed instruction corresponding to the said rotation deviation on the basis of a thread pitch;

means operatively connected to said rotation position detector for computing a feed correction value corresponding to the detected rotating position of the spindle on the basis of the thread pitch;

means operatively connected to said feed correction value computing means and said feed position detector for computing a feed deviation between the feed correction value and the feed amount of said spindle head;

means operatively connected to said feed deviation computing means for correcting the feed instruction on the basis of said feed deviation; and

means operatively connected to said correcting means for driving the feed motor in accordance with the corrected feed instruction.

3. In a thread cutting machine including a spindle for holding a thread cutting tool, a spindle head for supporting said spindle, a spindle motor for rotating said spindle, a feed motor for driving said spindle head, a detector for detecting a rotating position of said spindle, a detector for detecting a feed position and a feed amount of said spindle head, and wherein thread cutting is conducted under synchronous driving operation of said spindle motor and said feed motor, said thread cutting machine comprising:

means for computing a feed deviation between a feed instruction and a feed position of said spindle head detected by the feed position detector;

means operatively connected to said feed deviation computing means for driving the feed motor in accordance with the feed deviation;

means for computing feed speed and acceleration;

means for computing a rotation instruction corresponding to the computed feed speed and acceleration on the basis of a thread pitch;

means operatively connected to said feed position detector for computing a rotation correction value corresponding to the detected feed amount of said spindle head on the basis of the thread pitch;

means operatively connected to said rotation correction computing means and said spindle position detector for computing a rotation deviation between the rotation correction value and the rotating position of said spindle;

means operatively connected to said rotation deviation computing means for correcting the rotation instruction on the basis of said rotation deviation; and

,

means operatively connected to said correcting means for driving said spindle motor for rotating said spindle in accordance with the corrected rotation instruction.

4. The thread cutting machine according to claim 3 wherein said rotation instruction computing means serves to compute a feed acceleration in accordance with a feed instruction.

5. The thread cutting machine according to claim 3 wherein said rotation instruction computing means serves to compute a feed acceleration in accordance with the detected feed amount of said spindle head.

6. The thread cutting machine according to claim 3 wherein said rotation instruction computing means serves to compute a feed acceleration in accordance with the feed deviation.

7. In a thread cutting machine including a spindle for holding a thread cutting tool, a spindle head for supporting said spindle, a spindle motor for rotating said spindle, a feed motor for driving said spindle head, a detector for detecting a rotating position of said spindle, a detector for detecting a feed position and a feed amount of said spindle head, and wherein thread cutting working is conducted under synchronous driving operation of said spindle motor and said feed motor, said thread cutting machine comprising:

means for computing a rotation deviation between a rotation instruction and a rotating position of said spindle detected by the rotating position detector;

means operatively connected to said rotation deviation computing means for driving said spindle motor in accordance with the rotation deviation;

means for computing a rotation speed and an acceleration;

means for computing a feed instruction corresponding to the computed feed speed and acceleration on the basis of a thread pitch;

means operatively connected to said feed instruction computing means for computing a feed correction value corresponding to the detected rotating position of said spindle on the basis of the thread pitch;

means operatively connected to said feed correction computing means and said feed position detector for computing a feed deviation between the feed correction value and the detected feed amount of the spindle head;

means operatively connected to said feed deviation computing means for correcting the feed instruction on the basis of said feed deviation; and

means operatively connected to said correcting means for driving the feed motor in accordance with said corrected feed instruction.

8. The thread cutting machine according to claim 7, wherein said feed instruction computing means serves to compute a rotation acceleration in accordance with the rotation instruction.

9. The thread cutting machine according to claim 7 wherein said feed instruction computing means serves to compute a rotation acceleration in accordance with the rotating position of said spindle.

10. The thread cutting machine according to claim 7, wherein said feed instruction computing means serves to compute a rotation acceleration in accordance with the rotation deviation.