Rotary table device and method of controlling the rotary table device

Patent metadata

Field	Value
Publication number	US-10442050-B2
Application number	US-201816112981-A
Country	US
Kind code	B2
Filing date	Aug 27, 2018
Priority date	Sep 1, 2017
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

In a method of controlling a rotary table device, a clamp mechanism drive unit is controlled to unclamp a brake disk. Thereafter, a pressure of working fluid supplied to an unclamp fluid chamber is decreased, and a motor drive unit is controlled to rotate a motor. Then, the abrasion quantity of the piston and the clamp member is calculated based on a reference pressure and a pressure when the load torque of a spindle exceeded a reference load torque.

First claim

What is claimed is:

1. A rotary table device including a clamp mechanism, the clamp mechanism comprising:
a brake disk configured to rotate together with a spindle which rotates a workpiece;
a piston configured to move in a clamping direction in which the brake disk is clamped and an unclamping direction in which the brake disk is unclamped;
a clamp member configured to hold the brake disk between the clamp member and the piston which has moved in the clamping direction; and
a biasing member configured to bias the piston by a restoration force of elastic deformation in the clamping direction,
the rotary table device comprising:
a clamp mechanism drive unit configured to supply working fluid to a clamp fluid chamber to move the piston in the clamping direction, in a case of clamping the brake disk, and supply the working fluid to an unclamp fluid chamber to move the piston in the unclamping direction and change a pressure of the supplied working fluid, in a case of unclamping the brake disk,
a motor drive unit configured to drive the motor which rotates the spindle;
a pressure detection unit configured to detect the pressure of the working fluid;
a load detection unit configured to detect the load torque of the spindle;
a drive control unit configured to control the clamp mechanism drive unit to unclamp the brake disk, and thereafter, decrease the pressure of the working fluid supplied to the unclamp fluid chamber and control the motor drive unit to rotate the motor; and
an abrasion quantity calculation unit configured to calculate an abrasion quantity of the piston and the clamp member based on a reference pressure and the pressure of the working fluid when the load torque of the spindle exceeded the reference load torque.

2. The rotary table device according to claim 1 , wherein the reference load torque is a torque generated by adding a predetermined torque to the load torque of the spindle when the motor is rotated by unclamping the brake disk using the working fluid at a predetermined pressure.

3. The rotary table device according to claim 1 , wherein the reference pressure is a pressure of the working fluid when the load torque of the spindle exceeds the reference load torque, in a state where the piston and the clamp member have no abrasion, after the brake disk is unclamped, the pressure of the working fluid supplied to the unclamp fluid chamber is decreased, and the motor is rotated.

4. The rotary table device according to claim 1 , wherein the abrasion quantity calculation unit is configured to calculate the abrasion quantity of the piston and the clamp member using a following equation (1):
Δ W n =( V 0 −V n )· S/k   (1)

where ΔW n is the abrasion quantity calculated currently, V 0 is the reference pressure, V n is the pressure of the working fluid when the load torque of the spindle exceeded the reference load torque, S is an effective area of the unclamp fluid chamber, k is a modulus of elasticity of the biasing member, and n is an integer of 1 or more.

5. The rotary table device according to claim 1 , further comprising a remaining product life calculation unit configured to calculate a remaining product life until the abrasion quantity of the piston and the clamp member reaches a predetermined maximum abrasion quantity based on the abrasion quantity calculated by the abrasion quantity calculation unit.

6. The rotary table device according to claim 5 , wherein the remaining product life calculation unit is configured to calculate the remaining product life based on the abrasion quantity calculated in past and the abrasion quantity calculated currently by the abrasion quantity calculating unit, a time interval between a timing at which the abrasion quantity was calculated in the past and a timing at which the abrasion quantity was calculated currently by the abrasion quantity calculating unit, and the maximum abrasion quantity.

7. The rotary table device according to claim 6 , wherein the remaining product life calculation unit is configured to calculates the remaining product life using the following equation (2):
LT n =( T n −T n-j )·(Δ W max −ΔW n )/(Δ W n −ΔW n-j )  (2)

where LT n denotes the remaining product life, ΔW n denotes the abrasion quantity calculated currently, ΔW n-j denotes the abrasion quantity calculated j-th times before, T n denotes the timing at which the abrasion quantity ΔW n was calculated, T n-j denotes the timing at which the abrasion quantity ΔW n-j was calculated, ΔW max denotes the maximum abrasion quantity, n is an integer of 2 or more, and j denotes an integer of 1 or more but less than n.

8. A method of controlling a rotary table device including a clamp mechanism, the clamp mechanism comprising:
a brake disk configured to rotate together with a spindle which rotates a workpiece;
a piston configured to move in a clamping direction in which the brake disk is clamped and an unclamping direction in which the brake disk is unclamped;
a clamp member configured to hold the brake disk between the clamp member and the piston which has moved in the clamping direction; and
a biasing member configured to bias the piston by a restoration force of elastic deformation in the clamping direction,
the rotary table device comprising:
a clamp mechanism drive unit configured to supply working fluid to a clamp fluid chamber to move the piston in the clamping direction, in a case of clamping the brake disk, and supply the working fluid to an unclamp fluid chamber to move the piston in the unclamping direction and change a pressure of the supplied working fluid, in a case of unclamping the brake disk; and
a motor drive unit configured to drive the motor which rotates the spindle;
the method comprising the steps of:
detecting the pressure of the working fluid;
detecting the load torque of the spindle;
controlling the clamp mechanism drive unit to unclamp the brake disk, and thereafter, decrease the pressure of the working fluid supplied to the unclamp fluid chamber and control the motor drive unit to rotate the motor; and
calculating an abrasion quantity of the piston and the clamp member based on a reference pressure and the pressure of the working fluid when the load torque of the spindle exceeded the reference load torque.

9. The method of controlling the rotary table device according to claim 8 , wherein the reference load torque is a torque generated by adding a predetermined torque to the load torque of the spindle when the motor is rotated by unclamping the brake disk using the working fluid at a predetermined pressure.

10. The method of controlling the rotary table device according to claim 8 , wherein the reference pressure is a pressure of the working fluid when the load torque of the spindle exceeds the reference load torque, in a state where the piston and the clamp member have no abrasion, after the brake disk is unclamped, the pressure of the working fluid supplied to the unclamp fluid chamber is decreased, and the motor is rotated.

11. The method of controlling the rotary table device according to claim 8 , wherein, in the step of calculating the abrasion quantity, the abrasion quantity of the piston and the clamp member is calculated using a following equation (3):
Δ W n =( V 0 −V n )· S/k   (3)

where ΔW n is the abrasion quantity calculated currently, V 0 is the reference pressure, V n is the pressure of the working fluid when the load torque of the spindle exceeded the reference load torque, S is an effective area of the unclamp fluid chamber, k is a modulus of elasticity of the biasing member, and n is an integer of 1 or more.

12. The method of cont

Assignees

• Fanuc Corp

Inventors

• Xia Zhizhen

Classifications

• B23Q16/105 Primary

  clamping with a disc brake · CPC title

• B23Q17/008

  Life management for parts of the machine (tool life management B23Q17/0995) · CPC title

• B23Q1/52 Primary

  a single rotating pair · CPC title

• F16D66/00

  Arrangements for monitoring working conditions, e.g. wear, temperature · CPC title

• B23Q2220/004

  Rotary tables · CPC title