Machine tool and control method of machine tool

Patent metadata

Field	Value
Publication number	US-12269111-B2
Application number	US-202117923643-A
Country	US
Kind code	B2
Filing date	Jun 28, 2021
Priority date	Jun 30, 2020
Publication date	Apr 8, 2025
Grant date	Apr 8, 2025

Abstract

A machine tool and a control method for the machine tool, which determine the degree of misalignment during friction joint, are provided. The machine tool (an automatic lathe 1) includes: a first spindle 10 rotatably holding a first workpiece (a workpiece W1); a second spindle 20 arranged to face the first spindle and rotatably holding a second workpiece (a remaining workpiece W2); and a controller 40a, while rotating at least one of the first workpiece or the second workpiece, relatively moving the first spindle and the second spindle so as to get closer to each other and pushing a rear end portion of the second workpiece against a front end portion of the first workpiece to frictionally join the first and second workpieces. The controller has a misalignment amount detector detecting a misalignment amount s of the second workpiece with respect to the first workpiece during the friction joint.

First claim

The invention claimed is:

1. A machine tool comprising:
a first spindle rotatably holding a first workpiece;
a second spindle arranged so as to face the first spindle and rotatably holding a second workpiece;
a controller, while rotating at least one of the first workpiece held by the first spindle or the second workpiece held by the second spindle, relatively moving the first spindle and the second spindle so as to get closer to each other and pushing a rear end portion of the second workpiece against a front end portion of the first workpiece to frictionally join the first and second workpieces; and
a spindle mover comprising a motor configured to move the second spindle in a direction intersecting a rotation axis of the second spindle,
wherein the controller has a misalignment amount detector detecting a misalignment amount of the second workpiece with respect to the first workpiece during the friction joint,
wherein the misalignment amount detector obtains the misalignment amount of the second workpiece with respect to the first workpiece on the basis of a load applied to the motor.

2. The machine tool according to claim 1 , wherein the spindle mover is configured to move the second spindle in the direction intersecting the rotation axis of the second spindle during the friction joint on the basis of the misalignment amount of the second workpiece with respect to the first workpiece, which is detected by the misalignment amount detector.

3. The machine tool according to claim 2 , wherein a timing at which the second spindle is moved in the direction intersecting the rotation axis of the second spindle is immediately after the first spindle stops rotating, immediately before the first spindle stops rotating, or while rotation speed of the first spindle is gradually decreasing.

4. The machine tool according to claim 2 , wherein the controller has a misalignment direction detector detecting a misalignment direction of the second workpiece with respect to the first workpiece during the friction joint by comparing the misalignment amount of the second workpiece with respect to the first workpiece, which is detected by the misalignment amount detector, and a rotation phase of the first spindle.

5. The machine tool according to claim 4 , wherein the second spindle mover moves the second spindle in the direction intersecting the rotation axis of the second spindle so as to decrease the misalignment amount of the second workpiece with respect to the first workpiece on the basis of the misalignment amount of the second workpiece with respect to the first workpiece, which is detected by the misalignment amount detector, and the misalignment direction of the second workpiece with respect to the first workpiece, which is detected by the misalignment direction detector.

6. A control method of a machine tool including:
a first spindle rotatably holding a first workpiece;
a second spindle arranged so as to face the first spindle and rotatably holding a second workpiece transferred from the first spindle;
a controller having a misalignment amount detector and controlling operation of the first spindle and the second spindle and
a spindle mover comprising motor configured to move the second spindle in a direction intersecting a rotation axis of the second spindle, the control method comprising the steps of:
while rotating at least one of the first workpiece held by the first spindle or the second workpiece held by the second spindle, relatively moving the first spindle and the second spindle so as to get closer to each other and pushing a rear end portion of the second workpiece against a front end portion of the first workpiece to frictionally join the first and second workpieces;
detecting, via the misalignment amount detector, a misalignment amount of the second workpiece with respect to the first workpiece during friction joint by pushing the rear end portion of the second workpiece against the front end portion of the first workpiece, the misalignment amount detector obtaining the misalignment amount of the second workpiece with respect to the first workpiece on the basis of a load applied to the motor;
detecting a misalignment direction of the second workpiece with respect to the first workpiece during the friction joint; and
moving the second spindle in a direction intersecting a rotation axis of the second spindle during the friction joint so as to decrease the misalignment amount of the second workpiece with respect to the first workpiece on the basis of the detected misalignment amount of the second workpiece with respect to the first workpiece and the detected misalignment direction of the second workpiece with respect to the first workpiece.

7. The machine tool according to claim 1 , wherein the controller has a misalignment direction detector detecting a misalignment direction of the second workpiece with respect to the first workpiece during the friction joint by comparing the misalignment amount of the second workpiece with respect to the first workpiece, which is detected by the misalignment amount detector, and a rotation phase of the first spindle.

Assignees

• Citizen Watch Co Ltd

Inventors

• Kitakaze Ayako

Classifications

• B23Q2735/062

  in a lathe · CPC title

• B23Q2717/003

  in lathes · CPC title

• B23Q17/22

  for indicating or measuring existing or desired position of tool or work {(B23Q16/005 takes precedence)} · CPC title

• B23K20/1255

  Tools therefor, e.g. characterised by the shape of the probe · CPC title

• B23K20/125

  Rotary tool drive mechanism · CPC title