Numerical controller with machining time prediction unit and machining error prediction unit

• US 8,938,316 B2
• Filed: 02/23/2012
• Issued: 01/20/2015
• Est. Priority Date: 05/20/2011
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Otsuki, Toshiaki, Hanaoka, Osamu
• Primary Examiner(s): PATEL, RAMESH B
• Application Number:
  US13/403,006
• Publication Number:
  US 20120296462A1
• Time in Patent Office: 1,062 Days
• Field of Search: 700159-160, 700173-174, 700/181, 700/186, 700188-190, 700/192, 703/4, 703/13, 703/19, 703/22
• US Class Current: 700/160
• CPC Class Codes: G05B 19/4069 Simulating machining process on screen G05B19/4068 takes precedence
• CPC Class Codes: G05B 2219/35346 VMMC: virtual machining measuring cell simulate machining process with modeled errors, error prediction
• CPC Class Codes: G05B 2219/36219 Calculate machining information, like time, surface to be machined from program
• CPC Class Codes: G05B 2219/36252 Generate machining program based on a simulation to optimize a machine parameter
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

In connection with a machining program used in machining a workpiece by means of a machine tool controlled by a numerical controller, interpolation data, a command position point sequence, and a servo position point sequence for each processing period are determined by simulation by designating speed data for giving a machining speed and precision data for giving a machining precision. A predicted machining time for workpiece machining is determined based on the determined interpolation data, and a predicted machining error for workpiece machining is determined based on the determined command and servo position point sequences. Further, the precision data and the speed data are determined for the shortest predicted machining time within a preset machining error tolerance, based on a plurality of predicted machining times and a plurality of predicted machining errors.

Claims

1. A numerical controller for drivingly controlling a machine tool which machines a workpiece based on a machining program, the numerical controller comprising:

a designation unit for designating speed data for giving a machining speed and precision data for giving a machining precision;

a simulation unit which determines a command position point sequence and a servo position point sequence for each processing period by simulating a program analysis process, an interpolation process, a post-interpolation acceleration/deceleration process, and a servo operation, using the speed data and the precision data designated for the machining program by the designation unit;

a machining time prediction unit which determines a predicted machining time during which the workpiece will be machined in the simulation unit; and

a machining error prediction unit which determines a predicted machining error caused when the workpiece will be machined using the command position point sequence and the servo position point sequence determined by the simulation unit.

2. The numerical controller according to claim 1, wherein

the machining error prediction unit acquires the command position point sequence and the servo position point sequence for each processing period of the simulation by the simulation unit,

a distance from a specific command position in the command position point sequence to the servo position point sequence or a perpendicular line drawn from the specific command position to a line segment which connects adjacent points in each servo position, whichever is shorter, is determined to be an error in the specific command position, and

the greatest of the errors in the specific command positions is determined to be an error between the command position point sequence and the servo position point sequence.

3. The numerical controller according to claim 1, wherein

the machining error prediction unit acquires the command position point sequence and the servo position point sequence for each processing period of the simulation by the simulation unit,

a distance from a specific servo position in the servo position point sequence to the command position point sequence or a perpendicular line drawn from the specific servo position to a line segment which connects adjacent points in each command position, whichever is shorter, is determined to be an error in the specific servo position, and

the greatest of the errors in the specific servo positions is determined to be an error between the command position point sequence and the servo position point sequence.

4. The numerical controller according to claim 1, wherein

the machining error prediction unit acquires the command position point sequence and the servo position point sequence for each processing period of the simulation by the simulation unit,

a distance from a specific command position in the command position point sequence to the servo position point sequence or a perpendicular line drawn from the specific command position to a line segment which connects adjacent points in each servo position, whichever is shorter, is determined to be an error in the specific command position,

the greatest of the errors in the specific command positions is determined to be an error from the command position point sequence to the servo position point sequence,

a distance from a specific servo position in the servo position point sequence to the command position point sequence or a perpendicular line drawn from the specific servo position to a line segment which connects adjacent points in each command position, whichever is shorter, is determined to be an error in the specific servo position,

the greatest of the errors in the specific servo positions is determined to be an error from the servo position point sequence to the command position point sequence, and

the greater of the error from the command position point sequence to the servo position point sequence and the error from the servo position point sequence to the command position point sequence is determined to be an error between the command position point sequence and the servo position point sequence.

5. The numerical controller according to claim 1, wherein the machining time prediction unit and the machining error prediction unit determine a plurality of predicted machining times and a plurality of predicted machining errors based on a plurality of designated precision data and a plurality of designated speed data, and determine the precision data and the speed data for the shortest predicted machining time within a preset machining error tolerance, based on the plurality of predicted machining times and the plurality of predicted machining errors determined thereby.

6. The numerical controller according to claim 1, wherein

the numerical controller controls a multi-axis machine comprising a rotary axis,

the machining error prediction unit determines a three-dimensional command position point sequence and a three-dimensional servo position point sequence of a tool center point position based on the command position point sequence and the servo position point sequence, and

the error between the command position point sequence and the servo position point sequence is determined with the three-dimensional command position point sequence and the three-dimensional servo position point sequence used as the command position point sequence and the servo position point sequence, respectively.

7. The numerical controller according to claim 1, wherein the precision data is given by machining condition data based on an allowable acceleration or an allowable corner speed difference.