# US 10,442,050 B2 · Rotary table device and method of controlling the rotary table device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,442,050 B2 - Document ID: US10442050B2 - Status: Granted - Kind: B2 - Application number: 16/112,981 - Filed: 2018-08-27 - Published: 2019-03-07 - Granted: 2019-10-15 - Earliest claimed: 2017-09-01 - Assignees: Fanuc Corporation - Applicants: Fanuc Corporation - Inventors: Zhizhen Xia - Web page: https://patentgrep.com/patent/US10442050B2 ## CPC - B23Q 16/105: {clamping with a disc brake} - F16D 55/22: by clamping an axially-located rotating disc between movable braking members, e.g. movable brake discs or brake pads - F16D 66/00: Arrangements for monitoring working conditions, e.g. wear, temperature - B23Q 2220/004: Rotary tables - F16D 2066/006: {without direct measurement of the quantity monitored, e.g. wear or temperature calculated form force and duration of braking} - F16D 2121/06: for releasing a normally applied brake - B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) 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. ### Claim 4 (depends on 1) 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): ΔWn=(V0−Vn)·S/k (1) where ΔWn is the abrasion quantity calculated currently, V0 is the reference pressure, Vn 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. ### Claim 5 (depends on 1) 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. ### Claim 6 (depends on 5) 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. ### Claim 7 (depends on 6) 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): LTn=(Tn−Tn-j)·(ΔWmax−ΔWn)/(ΔWn−ΔWn-j) (2) where LTn denotes the remaining product life, ΔWn denotes the abrasion quantity calculated currently, ΔWn-j denotes the abrasion quantity calculated j-th times before, Tn denotes the timing at which the abrasion quantity ΔWn was calculated, Tn-j denotes the timing at which the abrasion quantity ΔWn-j was calculated, ΔWmax 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. ### Claim 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. ### Claim 9 (depends on 8) 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. ### Claim 10 (depends on 8) 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. ### Claim 11 (depends on 8) 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): ΔWn=(V0−Vn)·S/k (3) where ΔWn is the abrasion quantity calculated currently, V0 is the reference pressure, Vn 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. ### Claim 12 (depends on 8) The method of controlling the rotary table device according to claim 8, comprising the step of calculating 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 in the step of calculating the abrasion quantity. ### Claim 13 (depends on 12) The method of controlling the rotary table device according to claim 12, wherein, in the step of calculating the remaining product life, the remaining product life is calculated based on the abrasion quantity calculated in past and the abrasion quantity calculated currently in the step of calculating the abrasion quantity, 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 in the step of calculating the abrasion quantity, and the maximum abrasion quantity. ### Claim 14 (depends on 13) The method of controlling the rotary table device according to claim 13, wherein, in the step of calculating the remaining product life, the remaining product life is calculated using the following equation (4): LTn=(Tn−Tn-j)·(ΔWmax−ΔWn)/(ΔWn−ΔWn-j) (4) where LTn denotes the remaining product life, ΔWn denotes the abrasion quantity calculated currently, ΔWn-j denotes the abrasion quantity calculated j-th times before, Tn denotes the timing at which the abrasion quantity ΔWn was calculated, Tn-j denotes the timing at which the abrasion quantity ΔWn-j was calculated, ΔWmax 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.