CONTROL SYSTEM OF MACHINE TOOL

• US 20160089759A1
• Filed: 09/22/2015
• Published: 03/31/2016
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: MORITA, Yuuki, TAJIMA, Daisuke
• Granted Patent: US 10,001,212 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23Q 15/12 Adaptive control, i.e. adjusting itself to have a performance which is optimum according to a preassigned criterion
• CPC Class Codes: B23Q 17/008 Life management for parts of the machine tool life management B23Q17/0995
• CPC Class Codes: B23Q 17/0985 by measuring temperature
• CPC Class Codes: F16H 61/42 involving adjustment of a pump or motor with adjustable output or capacity F16H61/46 takes precedence
• CPC Class Codes: F16H 61/46 Automatic regulation in accordance with output requirements
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence

Abstract

A control system of a machine tool with a rotary type spindle and a feed axis which generates feed motion of the spindle, comprising a current detecting part which detects a current through a spindle motor for driving the spindle, a temperature detecting part which detects a motor temperature, a remaining time estimating part which uses a predetermined maximum allowable temperature and a detected temperature value by the temperature detecting part as the basis to estimate a remaining time until the motor temperature would reach the maximum allowable temperature on the assumption that the detected current value by the current detecting part at the time of the detected temperature value would continue to flow through the spindle motor, and a feed speed changing part which changes speed of the feed motion in accordance with the estimated value of the remaining time.

Claims

1. A control system of a machine tool with a rotary type spindle and a feed axis which generates feed motion of said spindle with respect to a workpiece, comprising

a current detecting part which detects a current which flows through a spindle motor which drives said spindle,

a temperature detecting part which detects a temperature of said spindle motor,

a remaining time estimating part which uses a predetermined maximum allowable temperature of said spindle motor and a detected temperature value by said temperature detecting part as the basis to estimate a remaining time until the temperature of said spindle motor reaches said maximum allowable temperature on the assumption that where the detected current value by said current detecting part at the time of the detected temperature value would continue to flow through said spindle motor, and

a feed speed changing part which changes speed of said feed motion in accordance with the estimated value of said remaining time by the remaining time estimating part.

2. The control system of a machine tool according to claim 1, wherein

said feed speed changing part decreases speed of said feed motion with a predetermined slope and by a predetermined amount of change if an estimated value of said remaining time by said remaining time estimating part is equal to or less than a predetermined threshold value.

3. The control system of a machine tool according to claim 2, wherein

said feed speed changing part decreases speed of said feed motion by said amount of change, and then increases speed of said feed motion increase by another amount of change smaller than said amount of change.

4. The control system of a machine tool according to claim 1, further comprising

a feed speed detecting part which detects speed of said feed motion,

a correspondence calculating part which uses the estimated value of said remaining time by said remaining time estimating part, the detected speed value by said feed speed detecting part, and the detected current value by said current detecting part as the basis to calculate the correspondence between speed of said feed motion and said remaining time if the estimated value of said remaining time by said remaining time estimating part is equal to or less than a predetermined threshold value, and

a feed speed specifying part which specifies a speed value of said feed motion corresponding to said threshold value of said remaining time, from said correspondence calculated by said correspondence calculating part, wherein

said feed speed changing part decreases speed of said feed motion toward the speed value specified by said feed speed specifying part.