JP2003156323A - Three-dimensional shape measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a highly accurate shape measurement while a contact-type probe is not tilted, even on a slope in a measuring apparatus by which the three-dimensional shape of a work is measured by scanning the shape by the contact-type probe supported by an elastic body. SOLUTION: The three-dimensional shape measuring apparatus, having the contact-type probe supported by a plurality of elastic bodies, is constituted in such a way that coefficients of elasticity of the plurality of elastic bodies are different. The measuring apparatus is constituted in such a way that, from among the plurality of elastic bodies, the coefficients of elasticity of the elastic bodies installed on the side closer to the work of the probe coming into contact with the work becomes larger than those of the elastic bodies installed on a side more distant from the work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring apparatus for measuring a three-dimensional shape of a measuring object with high accuracy by scanning the measuring object with a contact type probe supported by an elastic body.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No. 2000-298013 has been disclosed as a contact type probe to be mounted in three-dimensional surface shape measurement. The conventional example is shown in FIG. In FIG. 2, 201 is a probe shaft with a sphere that comes into contact with a workpiece at the tip, 202 is a workpiece to be measured by the probe 201, 203 is a probe holder, and 204 and 205 are for holding the probe 201 in the probe holder 203. It is a leaf spring. Reference numeral 206 denotes a displacement meter that detects the position of the probe 201. The probe holder 203 is driven in the Z-axis direction (probe vertical direction) (driving mechanism not shown) to bring the probe 201 into contact with the work 202. At this time, the position of the probe holder 203 in the probe axial direction is controlled so that the amount of displacement of the leaf springs 204 and 205 becomes constant, that is, the output of the displacement sensor 206 becomes constant. By tracing the surface of the work 202 in this state and measuring the positions of the probe holder 203 and the probe 201, the three-dimensional shape of the work 202 can be measured.

[0003]

Generally, in the contact type probe in the three-dimensional measuring apparatus as shown in the conventional example of FIG. 2, the leaf springs 204 and 205 are displaced by an extremely weak force in the axial direction of the probe. However, the ability to make almost no displacement in the direction orthogonal to the probe axis is required. That is, in the contact-type shape measurement, the shape of the work is measured by tracing the probe 201 on the work while controlling the position of the probe holder 203 so that the deformation amounts of the leaf springs 204 and 205 are constant. At this time, the leaf spring 20
The deformation amount of Nos. 4 and 205 becomes the contact pressure between the work and the probe 201. Generally, the smaller the contact pressure is, the more preferable the force of the leaf springs 204 and 205 in the probe axial direction is. On the other hand, Fig. 3 shows how a contact probe traces an inclined surface. In FIG. 3, f is the force that the contact point of the probe receives from the slope. If the surface is horizontal, the force received from the contact point of the probe is only in the Z direction, but in the case of an inclined surface, it also acts in the X direction, that is, in the direction orthogonal to the probe axis, as indicated by f in FIG. When the probe 201 receives a force in the X direction as indicated by f in FIG.
If the rigidity of the leaf springs 204 and 205 in the X direction is weak, the probe 201 moves to the probe holder 2.
It leans against 03. In this way, the probe 201
Is tilted with respect to the probe holder 203, even if the output of the displacement sensor 206 is the same, the probe 201 and the work 20
The positional relationship of No. 2 changes, and the distance between the probe holder 203 and the work 202 also changes, so that shape measurement cannot be performed correctly. Therefore, the leaf springs 204 and 205 are required to have a force that does not displace in the direction orthogonal to the probe axis.

However, if the thickness of the leaf springs 204 and 205 is reduced or the shape thereof is changed in order to reduce the contact pressure, the direction perpendicular to the probe axis also becomes weak, and the probe tilts to cause an error in measurement. Alternatively, there is a problem that the contact pressure becomes strong when a leaf spring having a high rigidity in a direction orthogonal to the probe axis is used so that the probe does not tilt.

The present invention has been devised in order to solve these problems, and a third-order method for accurately measuring a three-dimensional shape measurement in which a contact type probe supported by an elastic body scans an object to be measured. The original shape measuring device.

[0006]

In a three-dimensional shape measuring device for measuring a shape by scanning a three-dimensional shape of an object with a contact-type probe that is supported by two or more elastic bodies, the contact-type probe is supported. The elastic moduli of two or more elastic bodies are different. Further, of the two or more elastic bodies that support the probe shaft, the elastic body installed closer to the workpiece than the probe contacting the workpiece has a higher elastic modulus than the workpiece. Is larger than the elastic modulus of.

Two or more elastic bodies that support the probe shaft have different elastic moduli, and further, of the two or more elastic bodies that support the probe shaft, the elastic body is installed closer to the work than the probe contacting the work. By setting the elastic modulus of the elastic body to be larger than that of the elastic body installed farther from the work, the elastic modulus in the axial direction of the probe shaft can be kept small and the direction perpendicular to the axis of the probe shaft can be suppressed. Therefore, the elastic modulus can be relatively increased. As a result, the contact pressure of the probe to the measurement work is reduced, and the shape measurement error caused by the tilt of the probe is not generated.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

[0009]

1 is a view showing a cross section of a probe unit in which a probe shaft and a probe holder according to the present invention are combined.

In FIG. 1, reference numeral 101 denotes a probe, and a ball such as a steel ball or a ruby is adhered to the tip of the probe or 10 is attached by vacuum or the like.
It is fixed at 1. 102 is an object to be measured, and the probe 10
The tip sphere of 1 traces the surface of this work. 103
Is a probe holder, and 104 and 105 are leaf springs.
The probe 101 has a leaf spring 10 on the probe holder 103.
4 and 105, and the leaf spring 104,
The probe 101 is attached so that it can be displaced in the Z direction by the deformation of 105. In this embodiment, the probe 101 is replaced with the probe holder 103.
Of the leaf springs 104 and 105 fixed to the probe spring sphere, that is, the leaf spring 104 on the side closer to the work 102 is made thicker than the leaf spring 105 on the side farther from the work 102. Specifically, the leaf spring 104
Has a thickness of 100 μm, and the leaf spring 105 has a thickness of 50 μm. By making the leaf spring 104 thicker than the leaf spring 105, the leaf spring 104 becomes a spring having a larger elastic modulus. By doing so, the leaf spring 104 near the workpiece 102 also has a high rigidity in the lateral direction, that is, a rigidity in the X-axis direction. However, the rigidity in the Z direction is equal to that of the leaf springs 104 and 105.
Since the elastic modulus is combined, the thickness of the leaf spring 104 can be made lower than that of the leaf spring 105. In the case of this embodiment, the difference between the leaf spring 104 and the leaf spring 105 is only the thickness, and the other shapes are the same. FIG. 4 shows the leaf springs 104 and 105 in the vertical direction, that is, Z in FIG.
It is the shape seen from the direction. In FIG. 4, a hole 401 is a portion for fixing the probe shaft 101, a hole 402 is a portion for fixing the leaf spring to the work holder 103, and the work holder 103 is fixed at three positions.

Next, 106 is a reflecting mirror for the laser length measuring device. Reference numeral 107 denotes a probe shaft base to which the probe holder 103 is fixed. Probe shaft base 10
Although not shown in the drawing, 7 is an XY movement table (not shown) so that it can move in the vertical direction, that is, the Z-axis direction.
Supported by. The reflecting mirror 106 is attached so that the moving distance in the Z direction of the probe shaft base 107 to which the probe shaft 101 and the probe holder 103 are fixed can be measured by a laser length measuring machine from a measurement reference (not shown). .

A scale 108 is attached to the probe 101. The sensor 109 reads the position of the scale 108 and is fixed to the probe holder 103. The scale 108 is an optical scale, and the sensor 1
09 by the probe holder 101 of the probe shaft 101
The position with respect to 3 can be read without contact.

Next, the operation will be described. The work 102 and the probe 101 are initially separated from each other, and a Z-axis direction moving mechanism provided on the probe shaft base 107 is driven by a command from a computer or a controller (not shown) to drive the work 10.
The probe 101 is brought into contact with 2. At this time, the leaf spring 10
4 and 105 bend, and the position of the probe shaft 101 changes with respect to the probe holder 103. This change amount is read by the signals from the scale 108 and the sensor 109, and the movement of the probe shaft base 107 in the Z-axis direction is stopped at a predetermined change amount. The amount of change of the sensor 109 at this time is the contact pressure due to the bending of the leaf springs 104 and 105. When the output of the sensor 109 reaches a predetermined value, a command is issued to an XY drive mechanism (not shown) that supports the probe base 107 to move the work 102 within a desired range. At this time, the movement mechanism of the probe base 107 in the Z-axis direction controls in the Z-axis direction so that the output from the sensor 109 remains at a predetermined value. During this time, the probe shaft 1
The position of the probe shaft 101 and the probe base 107 with respect to the measurement reference is measured by the laser length measuring device at any time by the reflection mirror 106 attached to 01.
While moving in the XY directions in this way, the probe base 10
It is possible to measure the three-dimensional shape of the work 102 by controlling 7 in the Z-axis direction and reading the position of the reflection mirror 106 with a laser length measuring device.

The above is the operation of the three-dimensional shape measuring apparatus using the contact probe.

In the present invention, the leaf spring 104 and the leaf spring 105 have the same shape except for the thickness, but the elastic modulus may be changed by changing the shape. Also in this case, the leaf spring 10
It is desirable that the rigidity of No. 4 is larger than that of the leaf spring 105. In addition, the thickness of the leaf spring is t
1. When the thickness of the leaf spring 105 is t2, approximately t1 =
It is desirable to set so as to have a relationship of 2 × t2.

In the present invention, the probe 101 is supported by the probe holder 103 by two leaf springs 104 and 105, but it may be supported by three or more. At this time, it is desirable to increase the thickness of the leaf spring that supports the probe on the probe holder on the side closest to the workpiece with respect to the probe shaft, or to make the shape highly rigid.

Further, in the present invention, the probe shaft is in the vertical direction and the work 102 is located below the probe 101.
The structure may be such that the work is on the top and the probe shaft 101 approaches the work 102 from below. Similarly, the structure may be such that the probe axis moves not in the vertical direction but in the horizontal direction, that is, the X-axis direction and the Y-axis direction. Also at this time, the probe 101
The leaf spring for supporting the probe on the lobe holder 103 is preferably formed by increasing the thickness of the leaf spring that supports the probe on the probe holder on the side closer to the work or by increasing the rigidity.

[0018]

According to the present invention, the three-dimensional shape of an object is
In a three-dimensional shape measuring device that measures a shape by scanning with a contact probe supported by at least two elastic bodies, the elastic modulus of two or more elastic bodies supporting the probe shaft is different, Of the two or more elastic bodies that support the workpiece, the elastic modulus of the elastic body installed closer to the workpiece than the probe that contacts the workpiece is greater than the elastic modulus of the elastic body placed farther from the workpiece. In addition, the two or more elastic bodies that support the probe shaft are leaf springs, and the thickness of the leaf spring installed on the side closer to the work of the probe contacting the work is farther from the work. By making it thicker than the thickness of the leaf spring installed, while suppressing the elastic modulus of the probe shaft in the axial direction to a small value,
The elastic modulus can be relatively increased in the direction orthogonal to the axis of the probe shaft. As a result, the contact pressure of the probe with respect to the measurement work is reduced, while eliminating the shape measurement error caused by the tilt of the probe.

[Brief description of drawings]

FIG. 1 is a probe shaft cross-sectional view of a contact-type three-dimensional shape measuring apparatus embodying the present invention.

FIG. 2 is a sectional view of a probe shaft of a conventional contact-type three-dimensional shape device.

FIG. 3 is a conceptual diagram of a contact probe in contact with an inclined surface.

FIG. 4 is a shape view of a leaf spring supporting a probe shaft of a contact type three-dimensional measuring apparatus embodying the present invention.

[Explanation of symbols]

101 probe 102 DUT 103 probe holder 104, 105 leaf spring 106 reflective mirror 107 Probe axis base 108 scale 109 sensor

Claims (5)

[Claims] 1. A three-dimensional shape measuring device for measuring a shape by scanning a three-dimensional shape of an object with a contact-type probe that supports two or more elastic bodies, and two or more pieces that support the contact-type probe. A three-dimensional shape measuring apparatus characterized in that the elastic bodies of the elastic bodies have different elastic moduli. 2. The three-dimensional shape measuring apparatus according to claim 1, wherein, of the two or more elastic bodies supporting the contact type probe, a probe tip to be brought into contact with an object to be measured,
The elastic body installed closer to the elastic body should have a structure or shape such that it has a larger elastic modulus than the elastic body installed farther from the tip of the probe that contacts the measurement object. A three-dimensional shape measuring device characterized by. 3. The three-dimensional shape measuring apparatus according to claim 1, wherein the two or more elastic bodies that support the contact type probe are leaf springs. 4. The three-dimensional shape measuring apparatus according to claim 3, wherein two or more leaf springs supporting the contact type probe have different thicknesses. 5. The three-dimensional shape measuring apparatus according to claim 4, wherein one of the thicknesses of two or more leaf springs supporting the contact probe is closer to a probe tip to be brought into contact with an object to be measured. A three-dimensional shape measuring device characterized in that the thickness of the leaf spring installed is thicker than the thickness of the leaf spring installed farther from the tip of the probe that contacts the measurement object.