Control device for machine tool and machine tool including the control device

Patent metadata

Field	Value
Publication number	US-10241493-B2
Application number	US-201515129242-A
Country	US
Kind code	B2
Filing date	Mar 24, 2015
Priority date	Mar 26, 2014
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

To provide a machine tool and a control device for the machine tool that can smoothly cut a workpiece while segmenting chips by feeding a cutting tool in a feed direction while reciprocally vibrating the cutting tool along the feed direction on the basis of a condition set by a user. The machine tool (100) or the control device (C) includes: a setting unit (C1, C2) for utilizing a number of rotations of relative rotation of a workpiece (W) and the cutting tool, a number of reciprocal vibrations of the cutting tool per rotation of the relative rotation, and a vibration frequency dependent on a period in which the control device (C) can execute an operating instruction when the workpiece W is machined as parameters and for setting values of two of the parameters to a control section (C1); and a correcting unit (C1) for setting the remaining one of the parameters to a predetermined value and correcting the values of the two of the parameters set by the setting unit on the basis of the value of the remaining one of the parameters.

First claim

The invention claimed is:

1. A machine tool having:
a cutting tool for cutting a workpiece, a rotating unit for rotating the cutting tool and the workpiece relative to each other;
a feeding unit for feeding the cutting tool and the workpiece in a predetermined feed direction;
a vibration unit for reciprocally vibrating the cutting tool and the workpiece relative to each other; and
a control device having:
a numerical value setting section configured to set values of two parameters from the group consisting of a number of rotations of the cutting tool and the workpiece relative to each other, a number of vibrations of the reciprocal vibration per rotation of the cutting tool and the workpiece relative to each other, and a vibration frequency dependent on a period in which the control device can execute an operating instruction when the workpiece is machined; and
a control section for making the machine tool machine the workpiece via rotation of the cutting tool and the workpiece relative to each other, and via the feeding of the cutting tool to the workpiece with reciprocal vibration of the cutting tool and the workpiece relative to each other by the vibration unit, for setting the remaining one of the said parameters to a predetermined value, and for correcting the values of said two of the parameters set by the numerical value setting section in dependence on the value of the remaining one of said parameters.

2. The machine tool according to claim 1 , wherein the vibration unit reciprocally vibrates the cutting tool and the workpiece relative to each other along the feed direction.

3. The machine tool according to claim 2 , wherein the vibration unit reciprocally vibrates the cutting tool and the workpiece relative to each other so that a portion of the workpiece that is cut with the cutting tool in forward movement of the reciprocal vibration overlaps a portion of the workpiece that is cut with the cutting tool in backward movement of the reciprocal vibration.

4. The machine tool according to claim 1 , wherein the control section sets said remaining one of the parameters to a predetermined value and corrects the values of said two parameters so that the number of rotations will be inversely proportional to the number of vibrations with a constant that is based on the vibration frequency.

5. The machine tool according to claim 4 , wherein said two parameters are the number of rotations and the number of vibrations, and the control section determines the vibration frequency on the basis of a value calculated according to the number of rotations and the number of vibrations set by the numerical value setting section and corrects the value of the number of rotations or the number of vibrations set by the numerical value setting section to a predetermined value on the basis of the vibration frequency determined by the control section.

6. The machine tool according to claim 5 , wherein the numerical value setting section sets an allowable range of the number of vibrations, and wherein the control section calculates a value of the number of vibrations on the basis of the number of rotations set by the numerical value setting section and the vibration frequency determined by the control section, corrects the calculated value of the number of vibrations to a value within the allowable range, and corrects the value of the number of vibrations set by the numerical value setting section to the corrected value.

7. The machine tool according to claim 5 , wherein the control section calculates a value of the number of vibrations on the basis of the number of rotations set by the numerical value setting section and the vibration frequency determined by the control section, corrects the value of the number of vibrations set by the numerical value setting section to a value that is obtained by adding 0.5 to an integer closest to the calculated value of the number of vibrations, and corrects the value of the number of rotations set by the numerical value setting section to a value calculated from the corrected value of the number of vibrations and the vibration frequency determined by the control section.

8. The machine tool according claim 1 , wherein the control section sets the speed of forward movement in each reciprocal vibration of the cutting tool toward the workpiece to a speed slower than the speed of backward movement in each reciprocal vibration of the cutting tool.

9. The machine tool according to claim 1 , wherein
a predetermined vibration amplitude of the reciprocal vibration with which machining operation of the workpiece can be executed is preliminarily determined;
the control section controls said reciprocal vibration so that the amplitude of reciprocal vibration gradually increases to said predetermined vibration amplitude at the beginning of the machining operation; and
said control section sets the amplitude of the reciprocal vibration on the basis of a ratio of the amplitude to the predetermined vibration amplitude, the ratio being calculated by raising a ratio of an elapsed time to a time period needed to reach the predetermined vibration amplitude to a power of a predetermined number.

10. The machine tool according to claim 1 , wherein the machine tool comprises: a spindle, a spindle moving mechanism to move the spindle holding the workpiece in an axial direction; and a tool post moving mechanism to move a tool post holding the cutting tool toward the spindle, and the feeding unit includes the spindle moving mechanism and the tool post moving mechanism and feeds the cutting tool to the workpiece via cooperation of the spindle moving mechanism and the tool post moving mechanism.

11. The machine tool according to claim 1 , wherein a spindle holding the workpiece is fixed on the machine tool, the machine tool comprises a tool post moving mechanism to move a tool post holding the cutting tool in multiple directions, and the feeding unit includes the tool post moving mechanism and feeds the cutting tool to the workpiece by moving the tool post in a feed direction toward the spindle positioned in the feed direction.

12. The machine tool according to claim 1 , wherein a tool post holding the cutting tool is fixed on the machine tool, the machine tool comprises a spindle moving mechanism to move a spindle holding the workpiece in multiple directions, and the feeding unit includes the spindle moving mechanism and feeds the cutting tool to the workpiece by moving the spindle in a feed direction toward the tool post positioned in the feed direction.

Assignees

• Citizen Watch Co Ltd
• Citizen Machinery Co Ltd

Inventors

• Kitakaze Ayako
• Muramatsu Masahiro
• Oyama Toshinari
• Sannomiya Kazuhiko

Classifications

• G05B2219/49277

  Oscillating, swinging feed drive, for grinding · CPC title

• G05B19/19 Primary

  characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path · CPC title

• B23Q17/00

  Arrangements for {observing,} indicating or measuring on machine tools (for automatic control or regulation of feed movement, cutting velocity or position of tool or work B23Q15/00) · CPC title

• G05B2219/49382

  Movement reciprocating · CPC title

• B23B25/02

  Arrangements for chip-breaking in turning-machines (on cutting tools B23B27/22) · CPC title