Industrial machine and method for measuring amount of expansion/contraction of industrial machine

Patent metadata

Field	Value
Publication number	US-9664629-B2
Application number	US-201414514882-A
Country	US
Kind code	B2
Filing date	Oct 15, 2014
Priority date	Nov 11, 2013
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

An industrial machine includes a moving mechanism moving one of a probe and a tool relative to a work piece, using three displacement axes parallel to each of three orthogonal axis directions; a low thermal expansion member formed with a material having a smaller thermal expansion coefficient than a material forming a structural element of the moving mechanism; and an expansion/contraction measurer measuring, using the low thermal expansion member as a reference, an amount of expansion/contraction of the structural element in one of the three orthogonal axis directions, the expansion/contraction occurring due to a change in temperature.

First claim

What is claimed is:

1. An industrial machine comprising:
a moving mechanism configured to move one of a probe and a tool relative to a work piece, by using three moving axes parallel to each of three orthogonal axis directions;
a low thermal expansion member comprising a material having a smaller thermal expansion coefficient than a material forming a structural element of the moving mechanism; and
an expansion/contraction measurer configured to measure, using the low thermal expansion member as a reference, an amount of expansion/contraction of the structural element in one of the three orthogonal axis directions, the expansion/contraction occurring due to a change in temperature.

2. The industrial machine according to claim 1 , wherein the low thermal expansion member is provided in a hollow space located on an interior of the structural element.

3. The industrial machine according to claim 1 , wherein the expansion/contraction measurer includes one of a differential transformer-type displacement sensor having a contact stylus head, an eddy current-type displacement sensor, a capacitance-type displacement sensor, and an optical displacement sensor.

4. The industrial machine according to claim 1 , further comprising:
a temperature detection sensor configured to detect the temperature of the low thermal expansion member; and
an expansion/contraction corrector configured to calculate the amount of expansion/contraction of the low thermal expansion member based on the temperature, the thermal expansion coefficient of the low thermal expansion member, and dimensions of the low thermal expansion member at a reference temperature, the expansion/contraction corrector further configured to correct the amount of expansion/contraction of the structural element based on the amount of expansion/contraction of the low thermal expansion member.

5. The industrial machine according to claim 1 , wherein:
the three orthogonal axis directions include an X-axis direction, a Y-axis direction, and a Z-axis direction,
the moving mechanism comprises:
a base;
a Y-table supported by the base and configured to be moved in the Y-axis direction relative to the base;
a fixed bridge affixed to the base;
an X-slider supported by the fixed bridge and configured to be moved in the X-axis direction relative to the fixed bridge; and
a Z-ram supported by the X-slider, and configured to be moved in the Z-axis direction relative to the X-slider, the Z-ram further configured to hold one of the probe and the tool,

a top surface on which the work piece is configured to be installed is formed on the Y-table,
the top surface of the Y-table is orthogonal to the Z-axis direction,
the fixed bridge comprises:
a first column and a second column, each standing upright along the Z-axis direction on two sides in the X-axis direction straddling the Y-table; and
an X-beam supported by the first column and the second column and configured to guide the X-slider in the X-axis direction,

the low thermal expansion member comprises:
a first low thermal expansion member comprising a material having a smaller thermal expansion coefficient than the material forming the first column; and
a second low thermal expansion member comprising a material having a smaller thermal expansion coefficient than the material forming the second column, and

the expansion/contraction measurer is further configured to measure the amount of Z-axis direction expansion/contraction of the first column by using the first low thermal expansion member as the reference, and is further configured to measure the amount of Z-axis direction expansion/contraction of the second column by using the second low thermal expansion member as the reference.

6. The industrial machine according to claim 5 further comprising:
a Z-scale fixated to the Z-ram and extending in the Z-axis direction; and
a Z-detection device provided to the X-slider and configured to read a value of the Z-scale, wherein:
the first low thermal expansion member comprises a first top end and a first bottom end positioned respectively at each of two Z-axis direction sides,
the first bottom end is fixed so as to prevent displacement in the Z-axis direction relative to a base-side end of the first column, and the first top end is allowed to freely displace in the Z-axis direction relative to the first column due to a difference in thermal expansion between the first low thermal expansion member and the first column,
the second low thermal expansion member comprising a second top end and a second bottom end positioned respectively at each of two Z-axis direction sides,
the second bottom end is fixed so as to prevent displacement in the Z-axis direction relative to a base-side end of the second column, and the second top end is allowed to freely displace in the Z-axis direction relative to the second column due to a difference in thermal expansion between the second low thermal expansion member and the second column,
the expansion/contraction measurer is further configured to measure the amount of Z-axis direction expansion/contraction of the first column by using the first top end as a reference, and is further configured to measure the amount of Z-axis direction expansion/contraction of the second column by using the second top end as the reference,
Z-axis direction positions of the first bottom end and the second bottom end generally match a Z-axis direction position of the top surface of the Y-table, and
Z-axis direction positions of the first top end and the second top end generally match a Z-axis direction position of a detection reference point of the Z-detection device.

7. The industrial machine according to claim 1 , wherein:
the three orthogonal axis directions include an X-axis direction, a Y-axis direction, and a Z-axis direction,
the moving mechanism comprises:
a base having a top surface configured to accept a work piece to be installed thereon;
a Y-carriage having a bridge structure supported by the base and configured to be moved in the Y-axis direction relative to the base;
an X-slider supported by the Y-carriage and configured to be moved in the X-axis direction relative to the Y-carriage; and
a Z-ram supported by the X-slider, configured to be moved in the Z-axis direction relative to the X-slider, and further configured to hold one of the probe and the tool,

the top surface of the base is orthogonal to the Z-axis direction,
the Y-carriage comprises:
a column and a supporter, each standing upright along the Z-axis direction, separated from each other in the X-axis direction; and
an X-beam supported by the column and the supporter and configured to guide the X-slider in the X-axis direction,

the low thermal expansion member comprises:
a first low thermal expansion member comprising a material having a smaller thermal expansion coefficient than the material forming the column; and
a second low thermal expansion member comprising a material having a smaller thermal expansion coefficient than the material forming the supporter, and

the expansion/contraction measurer is further configured to measure the amount of Z-axis direction expansion/contraction of the column by using the first low thermal expansion member as a reference, and is further configured to measure the amount of Z-axis direction expansion/contraction of the supporter by using the second low thermal expansion member as the reference.

8. The industrial machine according to claim 7 , further comprising:
a Z-scale fixated to the Z-ram and extending in the Z-axis direction; and
a Z-detection device provided to the X-slider and reading a value of the Z-scale, wherein:
the first low thermal expansion member comprises a first top end and a first botto

Assignees

• Mitutoyo Corp

Inventors

• Sakai Hisayoshi

Classifications

• G01B5/0014

  due to temperature (on machine tools B23Q11/0003) · CPC title

• G01N25/16 Primary

  by investigating thermal coefficient of expansion · CPC title

• G01B5/008

  using coordinate measuring machines · CPC title

• G01B21/045

  Correction of measurements (G01B9/02055 takes precedence) · CPC title