Numerical control apparatus

Patent metadata

Field	Value
Publication number	US-9897992-B2
Application number	US-201214400879-A
Country	US
Kind code	B2
Filing date	May 22, 2012
Priority date	May 22, 2012
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A numerical control apparatus that controls a machine tool including a plurality of linear axes and rotation axes, and controls a relative tool posture with respect to work on a table includes a program reading unit that sequentially reads a tool posture with respect to the work from a machining program, a determining unit that determines whether the read tool posture is within a predetermined tool posture range, a tool-posture control unit that determines control content of the tool posture according to the determination by the determining unit, and an interpolation/acceleration and deceleration processing unit that controls the linear and rotation axes according to the control content of the tool posture. When the read tool posture is within the predetermined range, the tool-posture control unit determines rotation axis angles of the rotation axes such that a change of tool posture from the last tool posture is limited.

First claim

The invention claimed is:

1. A numerical control apparatus that controls a machine tool including a plurality of linear axes and a first rotation axis and a second rotation axis and controls a relative tool posture of a tool with respect to work placed on a table, the numerical control apparatus comprising:
a program reading unit that sequentially reads, from a machining program including a plurality of blocks described by a command code to the machine tool, for each of the blocks, a tool posture of the tool with respect to the work;
a determining unit that determines whether or not the read tool posture is within a predetermined tool posture range;
a tool-posture control unit that determines control content of the tool posture according to a result of the determination by the determining unit; and
an interpolation/acceleration and deceleration processing unit that controls the plurality of linear axes and the two or more rotation axes according to the determined control content of the tool posture, wherein:
the predetermined tool posture range includes a peculiar posture in which a principal plane of the table and a center axis of a tool cross perpendicularly to each other, and which corresponds to an angle of the first rotation axis,
when, for each of the read blocks, an angle of the first rotation axis at a start point of the read block is within the predetermined tool posture range and an angle of the first rotation axis at an end point of the read block is within the predetermined tool posture range, the determining unit determines that the read tool posture is within the predetermined tool posture range, and
when the read tool posture is within the predetermined tool posture range, the tool-posture control unit determines a rotation axis angle of the second rotation axis such that a change of an angle of the second rotation axis from a last angle of the second rotation axis is limited to a certain value and when the read tool posture is outside of the predetermined tool posture range, the tool-posture control unit determines the rotation axis angle of the second rotation axis such that the change of the angle of the second rotation axis angle is permitted to exceed the certain value.

2. The numerical control apparatus according to claim 1 , further comprising a storing unit that stores the tool posture controlled by the interpolation/acceleration and deceleration processing unit.

3. The numerical control apparatus according to claim 1 , wherein, when the read tool posture is within the predetermined tool posture range, the tool-posture control unit determines a rotation axis angle of the second rotation axis such that the last angle of the second rotation axis is retained.

4. The numerical control apparatus according to claim 1 , wherein the tool-posture control unit changes a rotation axis angle of the second rotation axis to gradually increase or gradually reduce the rotation axis angle of the second rotation axis from a tool posture at the time of an entrance of the tool into the predetermined tool posture range to a tool posture immediately before an exit of the tool from the predetermined tool posture range.

5. The numerical control apparatus according to claim 4 , wherein the tool-posture control unit changes, according to moving distances of the linear axes, a unit amount by which the rotation axis angles should be gradually increased or gradually reduced.

6. The numerical control apparatus according to claim 1 , wherein, when the read tool posture is within the predetermined tool posture range, the tool-posture control unit determines a rotation axis angle of the first rotation axis such that a change of an angle of the first rotation axis from a last angle of the first rotation axis is not limited.

7. The numerical control apparatus according to claim 1 , wherein
the peculiar posture is a posture where the angle of the first rotation axis is 0 degrees, the principal plane of the table and the center axis of the tool crossing perpendicularly to each other at the angle, and
the predetermined tool posture range is a range of predetermined angles with respect to the angle of the first rotation axis at the peculiar posture.

Assignees

• Tsuda Takeshi
• Suzuki Keiichiro
• Mitsubishi Electric Corp

Inventors

• Tsuda Takeshi
• Suzuki Keiichiro

Classifications

• G05B2219/41188

  Compensate position error between two different axis as function of type of transducer · CPC title

• G05B2219/37618

  Observe, monitor position, posture of tool · CPC title

• G05B19/4103 Primary

  Digital interpolation · CPC title

• G05B19/19 Primary

  characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path · CPC title