TAPPING MACHINE

• US 20130039707A1
• Filed: 06/29/2012
• Published: 02/14/2013
• Est. Priority Date: 08/08/2011
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: OKITA, Tadashi, TAKAYAMA, Kenichi
• Granted Patent: US 8,662,799 B2
• Time in Patent Office: Days
• US Class Current: 408/9
• CPC Class Codes: B23G 1/18 Machines with one working spindle
• CPC Class Codes: G05B 19/416 characterised by control of velocity, acceleration or deceleration G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/41082 Timer, speed integration to control duration of backlash correction
• CPC Class Codes: G05B 2219/41216 Two lookup tables, for forward and reverse movement
• 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
• CPC Class Codes: Y10T 408/172 Responsive to Tool

Abstract

A tapping machine (1) executes a tapping operation by operating a spindle motor (21) and a feed axis motor (31) in synchronization, and includes a spindle reversal detector unit (34) for detecting the reversed operation of the spindle during the tapping operation, and a reverse correction amount production unit (35) for producing a reverse correction amount for improving follow-up performance of reversed operation of the feed axis at the time when the reversed operation of the spindle is detected by the spindle reversal detector unit (34). When the reversed operation is detected by the spindle reversal detector unit, the reverse correction amount produced by the reverse correction amount production unit (35) is added to the speed instruction on a speed control loop of the feed axis control unit (30) or to an integrator (41) of the speed control loop.

Claims

1. A tapping machine comprising:

a spindle motor for rotating a tapping tool about a spindle;

a rotational angle detector unit for detecting the rotational angle of said spindle motor or the spindle;

a feed axis motor for driving a feed axis to which said tapping tool is attached;

a position detector unit for detecting the position of said feed axis motor or said feed axis;

a move instruction value production unit for producing a move instruction value for said spindle motor;

a spindle control unit for driving said spindle motor based on a position deviation between said move instruction value produced by said move instruction value production unit and the rotational angle detected by said rotational angle detector unit;

a feed axis synchronization instruction value production unit for producing a move instruction value for the feed axis based on said detected rotational angle and a screw pitch of said tapping tool; and

a feed axis control unit for driving said feed axis motor based on a position deviation between said move instruction value produced by said feed axis synchronization instruction value production unit and the position value detected by said position detector unit, to thereby execute the tapping operation by operating said spindle motor and said feed axis motor in synchronization;

said tapping machine, further, comprising;

a spindle reversal detector unit for detecting the reversed operation of said spindle during the tapping operation; and

a reverse correction amount production unit for producing a reverse correction amount for improving follow-up performance of reversed operation of said feed axis at the time when the reversed operation of said spindle is detected by said spindle reversal detector unit;

wherein when the reversed operation is detected by said spindle reversal detector unit, the reverse correction amount produced by said reverse correction amount production unit is added to the speed instruction on a speed control loop of said feed axis control unit or to an integrator of said speed control loop.

2. The tapping machine as set forth in claim 1, wherein said spindle reversal detector unit detects the reversed operation of said spindle if a real moving amount of said spindle or said spindle motor as monitored in a predetermined control period is not zero and has a sign different from that of the real moving amount of the last time.

3. The tapping machine as set forth in claim 1, wherein a predetermined value is added to said reverse correction amount over a predetermined period of time.

4. The tapping machine as set forth in claim 1, wherein an initial value of said reverse correction amount is calculated based upon a torque instruction of just before the reversed operation of said feed axis motor or upon said integrator, said reverse correction amount decreasing depending upon the torque instruction after the reversed operation of said feed axis motor, upon the integrator of the speed loop, or upon the moving distance of said feed axis motor.

5. The tapping machine as set forth in claim 1, wherein said reverse correction amount varies in proportion to a synchronization error between the spindle and the feed axis motor.

6. The tapping machine as set forth in claim 2, wherein a predetermined value is added to said reverse correction amount over a predetermined period of time.

7. The tapping machine as set forth in claim 2, wherein an initial value of said reverse correction amount is calculated based upon a torque instruction of just before the reversed operation of said feed axis motor or upon said integrator, said reverse correction amount decreasing depending upon the torque instruction after the reversed operation of said feed axis motor, upon the integrator of the speed loop, or upon the moving distance of said feed axis motor.

8. The tapping machine as set forth in claim 2, wherein said reverse correction amount varies in proportion to a synchronization error between the spindle and the feed axis motor.