Device and method for controlling machine tool

• US 7,847,502 B2
• Filed: 01/02/2008
• Issued: 12/07/2010
• Est. Priority Date: 01/04/2007
• Status: Active Grant

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Ma, Chengbin, Okita, Tadashi, Iwashita, Yasusuke, Kawamura, Hiroyuki
• Primary Examiner(s): Duda; Rina I
• Application Number:
  US12/003,818
• Publication Number:
  US 20080164834A1
• Time in Patent Office: 1,070 Days
• Field of Search: 318/567, 318/568.22, 318/569, 318/571, 318/600, 318/632
• US Class Current: 318/567
• 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
• CPC Class Codes: G05B 2219/49177 Runout, eccentricity, unbalance of tool or workpiece
• CPC Class Codes: G05B 2219/49313 Machining about eccentric center different from rotational center of workpiece
• CPC Class Codes: G05B 2219/50174 Machine tool y-1, y-2, z, A-axis, table x, c-axis

Abstract

A device for controlling a feed motion of a feed control axis and a rotary motion of a rotary control axis, both axes being provided in a machine tool so that the rotary control axis is fed along the feed control axis. The device includes an interference estimating section estimating an interference generated between the feed control axis and the rotary control axis, based on a position command instructed to at least one of the feed control axis and the rotary control axis and a position and mass information of an eccentric load carried by the rotary control axis; and a command correcting section correcting a current command given to at least one of the feed control axis and the rotary control axis, based on the interference estimated by the interference estimating section.

Claims

1. A device for controlling a feed motion of a feed control axis and a rotary motion of a rotary control axis, said feed control axis and said rotary control axis being provided in a machine tool so that said rotary control axis is fed along said feed control axis, comprising:

an interference estimating section estimating an interference generated between said feed control axis and said rotary control axis, based on a position command instructed to at least one of said feed control axis and said rotary control axis and a position and mass information of an eccentric load carried by said rotary control axis, by calculating a force exerted on said rotary control axis due to a thrust applied to said eccentric load during the feed motion of said feed control axis, or by calculating a force exerted on said feed control axis due to a centripetal force and a tangential force applied to said eccentric load during the rotary motion of said rotary control axis; and

a command correcting section correcting a current command given to at least one of said feed control axis and said rotary control axis, based on said interference estimated by said interference estimating section.

2. A device as set forth in claim 1, wherein said interference estimating section estimates said interference prior to, by one or more control periods, a period of a motion control of at least one of said feed control axis and said rotary control axis executed in accordance with said position command;

and wherein said command correcting section corrects said current command at said period of said motion control.

3. A device as set forth in claim 1, further comprising a constant changing section changing a calculation constant used by said interference estimating section to estimate said interference, in response to a change in said eccentric load.

4. A device as set forth in claim 1, further comprising an eccentricity information estimating section estimating said position and mass information of said eccentric load, based on an interference-basis current command instructed to either one of said feed control axis or said rotary control axis in a state where said interference estimating section does not estimate said interference;

wherein said interference estimating section estimates said interference by using said position and mass information estimated by said eccentricity information estimating section.

5. A method for controlling a feed motion of a feed control axis and a rotary motion of a rotary control axis, said feed control axis and said rotary control axis being provided in a machine tool so that said rotary control axis is fed along said feed control axis, comprising:

estimating an interference generated between said feed control axis and said rotary control axis, based on a position command instructed to at least one of said feed control axis and said rotary control axis and a position and mass information of an eccentric load carried by said rotary control axis, by calculating a force exerted on said rotary control axis due to a thrust applied to said eccentric load during the feed motion of said feed control axis, or by calculating a force exerted on said feed control axis due to a centripetal force and a tangential force applied to said eccentric load during the rotary motion of said rotary control axis; and

correcting a current command given to at least one of said feed control axis and said rotary control axis, based on said interference thus estimated.

6. A method as set forth in claim 5, wherein estimating an interference includes estimating said interference prior to, by one or more control periods, a period of a motion control of at least one of said feed control axis and said rotary control axis executed in accordance with said position command;

and wherein correcting a current command includes correcting said current command at said period of said motion control, based on said interference thus estimated.

7. A method as set forth in claim 5, further comprising, when estimating an interference, changing a calculation constant used to estimate said interference, in response to a change in said eccentric load.

8. A method as set forth in claim 5, further comprising estimating said position and mass information of said eccentric load, based on an interference-basis current command instructed to either one of said feed control axis or said rotary control axis in a state where said interference is not estimated;

wherein estimating an interference includes estimating said interference by using said position and mass information thus estimated.