JP7310618B2 - Contact probe and coordinate measuring device - Google Patents

Description

The present invention relates to contact probes and coordinate measuring devices.

There is known a three-dimensional measuring apparatus that measures the coordinates of a workpiece by attaching a probe to the tip of a moving unit that can move in any direction and scanning the workpiece while the tip of the probe shaft is in contact with the workpiece (Patent Document 1-3).
A hard tip ball is provided at the tip of the probe shaft, and the three-dimensional measuring device detects the coordinates of the probe when the tip ball provided on the probe shaft is brought into contact with the workpiece and scanned. to measure the dimensions and shape of the workpiece.

JP 2006-329862 A Japanese Utility Model Laid-Open No. 1-160301 Japanese Unexamined Patent Application Publication No. 2006-201105

However, when measuring the size and shape of a workpiece including a narrow part such as a minute groove, if the diameter of the tip ball provided on the probe shaft is larger than the size of the narrow part, the tip ball may not be the workpiece to be measured. It becomes difficult to contact the position. In the probe used in the conventional three-dimensional measuring device, in order to secure the rigidity of the probe shaft, the diameter of the tip ball is about φ0.3mm, and the diameter of the probe shaft is about 0.2mm. ing. Even if such a minimum size probe is used, if the radius of curvature of the groove to be measured is smaller than the radius of curvature of the tip ball, the tip ball cannot be inserted into the groove and the tip ball cannot be positioned at the desired measurement position. cannot be contacted.

In that case, it is conceivable to further reduce the size of the tip ball and the probe shaft, but reducing the size to below the minimum size of the probe significantly reduces the mechanical strength of the probe itself. As a result, when the tip ball is brought into contact with a workpiece, it becomes difficult for the probe to receive the reaction force from the tip ball, and the probe may be deformed or damaged in some cases. In addition, if the size of the probe remains the same and only the tip ball is made smaller, even if the tip ball is of a size that allows it to be inserted into the narrow groove of the object to be measured, the probe shaft will be bent during the process of inserting the tip ball into the groove. It interferes with other parts of the workpiece, and the tip ball cannot reach the measurement surface of the groove, making measurement impossible.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a contact probe and a coordinate measuring apparatus that are capable of simple and highly accurate measurement while securing the strength of the probe even in a narrow portion of a workpiece. .

The present invention consists of the following configurations.
(1) A contact probe comprising a probe shaft and a contact portion fixed to the probe shaft,
The probe shaft portion has at least one support shaft that supports the contact portion at its tip,
The contact portion is
a contact portion main body having a circular or elliptical cross-sectional shape along the longitudinal direction of the support shaft;
at least one protrusion provided on the outer periphery of the contact portion main body and protruding radially outward;
has
The curvature radius of the cross-sectional shape including the longitudinal center line of the support shaft at the tip of the protrusion is smaller than the curvature radius of the cross-sectional shape including the longitudinal center line at the outer peripheral edge of the contact portion main body.
Contact probe.
(2) the contact probe according to (1) above;
and a probe support that supports the contact probe,
A coordinate measuring apparatus for measuring the coordinates of the work by relatively scanning the work while the protrusion provided on the contact portion of the contact probe is in contact with the work and measuring the position of the contact probe.

According to the present invention, it is possible to perform simple and highly accurate measurement while securing the strength of the probe even in a narrow portion of the work.

FIG. 1 is a perspective view of a coordinate measuring device. FIG. 2 is a side view of the contact probe of the first configuration example. FIG. 3 is a bottom view of the contact-type probe viewed from below in the axial direction of the probe shaft. FIG. 4 is a cross-sectional view of the contact portion of the contact-type probe vertically bisected. FIG. 5 is an explanatory diagram showing how coordinates of a workpiece are measured by a contact probe. FIG. 6 is an explanatory diagram schematically showing the operation of the contact-type probe. FIG. 7 is a partially enlarged cross-sectional view of the work in the axial direction, showing the dimensions of the contact portion of the contact probe and the work. FIG. 8 is a partially enlarged plan view of the work shown in FIG. 7 as viewed from above in the axial direction. 9A and 9B are diagrams showing another example of the contact portion that constitutes the contact-type probe, in which (A) is a bottom view of the contact portion provided with two protrusions, and (B) is a contact portion provided with three protrusions. It is a bottom view of the part. FIG. 10 is a perspective view of the contact portion in the first modified example of the contact probe. FIG. 11 is a perspective view of a contact portion in a second modification of the contact probe. FIG. 12 is an explanatory diagram showing how the contact probe for the second configuration example is attached to the electric micrometer and the measurement is performed. FIG. 13 is an explanatory diagram showing how the contact probe for the third configuration example is attached to the dial gauge for measurement. FIG. 14 is a schematic perspective view of a contact probe of a fourth configuration example. 15 is an enlarged view of the A portion of the contact probe shown in FIG. 14. FIG. FIG. 16 is an explanatory diagram showing how the contact probe shown in FIG. 14 is used to measure a workpiece.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a case where an outer ring of a rolling bearing is used as a workpiece to be measured will be described as an example, but the object to be measured is not limited to this.

<First configuration example>
(Configuration of coordinate measuring device)
FIG. 1 is a perspective view of a coordinate measuring apparatus 100. FIG.
A coordinate measuring apparatus 100 includes a base 11 , a horizontal guide mechanism 21 and a support block 25 .
A surface plate 15 having a horizontal (XY plane) stage surface 13 is arranged on the upper surface of the base 11 . A fixing jig 17 is fixed to the stage surface 13 , and the workpiece W is positioned on the stage surface 13 by the fixing jig 17 .

Here, the X-, Y-, and Z-axes orthogonal to each other are defined as the XY plane for the stage surface 13 and the Z direction for the vertical direction. The Y-axis is the moving direction of the horizontal guide mechanism 21 and the X-axis is the moving direction of the support block 25 .

The horizontal guide mechanism 21 has a guide portion 23 that supports the support block 25 so as to be movable in the X-axis direction, and a pair of struts 19 that support the guide portion 23 . The lower sides of the pair of struts 19 are supported by both sides of the surface plate 15 of the base 11 so as to be movable in the Y direction. The horizontal guide mechanism 21 is driven in the Y direction by a drive source (not shown) to allow the support block 25 to move in the Y direction.

The support block 25 supported by the guide portion 23 can be moved in the X direction by being driven by a drive source (not shown).

Below the support block 25, a measuring head 27 is supported so as to be able to move up and down. The measuring head 27 can be moved in the Z direction by being driven by a drive source (not shown). Thereby, the measuring head 27 is movable in the X, Y, and Z directions.

The measuring head 27 is provided with a probe supporting portion 29 at its lower end. A contact probe 41 having a probe shaft portion 45 and a contact portion 43 shown in FIG. 2 is attached to the tip of the probe support portion 29 .

As shown in FIG. 1, the contact probe 41 can be moved to any position in a three-dimensional space by moving the horizontal guide mechanism 21 in the Y direction and the support block 25 in the X and Z directions.

In the coordinate measuring apparatus 100 configured as described above, first, the workpiece W is positioned and fixed on the stage surface 13 of the surface plate 15 using the fixing jig 17 . Then, the contact probe 41 is relatively scanned along the surface of the work W while the contact portion 43 of the contact probe 41 is in contact with the surface of the fixed work W. As a result, the dimensions and shape of the workpiece W are measured by scanning.

(Configuration of contact probe)
FIG. 2 is a side view of the contact probe 41 of the first configuration example. FIG. 3 is a bottom view of the contact-type probe 41 viewed from below the probe shaft portion 45 in the axial direction.
The contact-type probe 41 has a rod-shaped probe shaft portion (support shaft) 45 and a contact portion 43 fixed to the tip of the probe shaft portion 45 .

The contact portion 43 has a contact portion main body 61 and a plurality of (four in total in this configuration) projections 71A, 71B, 71C, and 71D provided on the outer circumference of the contact portion main body 61 . The contact portion main body 61 has a spherical outer peripheral surface and a circular cross-sectional shape along the longitudinal direction of the probe shaft portion 45 . The protrusions 71A, 71B, 71C, and 71D are arranged at the maximum diameter portion in a cross section including the longitudinal centerline of the probe shaft portion 45 of the contact portion main body 61, and protrude radially outward from the outer peripheral surface of the contact portion main body 61. there is These multiple protrusions 71A, 71B, 71C, and 71D are arranged on the outer periphery of the contact portion main body 61 at regular intervals in the circumferential direction around the longitudinal center line of the probe shaft portion 45 .

Moreover, the contact-type probe 41 may be attached to the probe support portion 29 via the holder 51 when the outer diameter of the probe shaft portion 45 is small (for example, 1 mm or less). For the holder 51 , a suitable size is selectively used according to the size of the contact probe 41 . The holder 51 has a mounting portion 53 formed with a male screw having a diameter larger than that of the probe shaft portion 45 and a probe holding portion 55 having a chuck hole 57 . The contact probe 41 is fixed to the measuring head 27 by screwing the attachment portion 53 to the internal thread (not shown) of the probe support portion 29 . An end portion of the probe shaft portion 45 is inserted into the chuck hole 57 to detachably support the probe shaft portion 45 .

Although the probe shaft portion 45 is shown here as having a cylindrical shape, it may have another shape such as a prismatic shape or a conical shape as long as it can support the contact portion main body 61 . Further, the contact portion main body 61 is not limited to a spherical shape, and may have other shapes such as a shape (for example, an ellipsoid) in which the cross section perpendicular to the longitudinal direction of the probe shaft portion 45 has a long axis and a short axis. good. The contact portion main body 61 may be an ellipsoid having an elliptical cross-sectional shape along the longitudinal direction of the probe shaft portion 45 . It is preferable that the contact portion main body 61 has a shape in which the maximum width in the direction perpendicular to the longitudinal direction is larger than the maximum width in the longitudinal direction of the probe shaft portion 45, because the projection can be inserted into a narrower area.

By exchanging the holder 51 with a holder 51 having an appropriate size, the contact probe 41 having the above configuration can be held by the probe support portion 29 in various sizes.

A measurement pressure is applied to the probe shaft portion 45 when the contact portion 43 is brought into contact with the workpiece W to perform coordinate measurement. Therefore, the probe shaft portion 45 requires rigidity to the extent that it does not bend greatly due to this measurement pressure. On the other hand, if a strong external force were to act, it is preferable to use a material that deforms itself and suppresses the influence on the probe supporting portion 29 . For this reason, the probe shaft portion 45 is preferably made of a metal material such as copper, which has appropriate rigidity and flexibility. The probe shaft portion 45 may be made of an aluminum material other than the copper material, or may be made of a stainless steel material as necessary.

Each of the projections 71A, 71B, 71C, and 71D shown in FIG. 3 is composed of a spherical body 73 (in the following description, the projections 71A, 71B, 71C, and 71D are also referred to as a spherical body 73). Each ball 73 is inserted into a through-hole formed in the contact portion main body 61 and fixed.

FIG. 4 is a cross-sectional view of the contact portion 43 of the contact-type probe 41 vertically bisected (a cross-sectional view along the longitudinal direction of the probe shaft portion).
The contact portion main body 61 is formed with a housing recess 65 that is a through hole. The accommodation recess 65 is formed along the radial direction perpendicular to the axial direction of the probe shaft portion 45 through the spherical center Oc of the contact portion main body 61 . The housing recess 65 has an inner diameter that is the same as or slightly larger than the outer diameter of the spherical body 73 . Further, the accommodation recess 65 may have a tapered shape with a smaller diameter toward the center Oc of the contact portion main body 61 .

Half of the ball 73 is inserted into the housing recess 65, and in this state, the ball 73 is fixed to the housing recess 65 with an adhesive. Therefore, the remaining half of the sphere 73 protrudes radially outward from the surface of the contact portion main body 61 to form protrusions 71A, 71B, 71C, and 71D. On the non-projecting side of the sphere 73, half of the spherical surface is fixed to the inner surface of the receiving recess 65 with an adhesive. That is, since the hemispherical portion of the sphere 73 up to the equator is inserted into the housing recess 65, the sphere 73 is joined to the inner wall surface of the housing recess 65 over the entire circumference of the equator position, and the housing recess 65 is filled with the adhesive. By doing so, the half of the spherical surface on the non-projecting side of the sphere 73 functions as a joint surface. Therefore, when the ball 73 is fixed with the adhesive, it is firmly fixed to the housing recess 65 . The accommodation recess 65 formed in the contact portion main body 61 is not limited to a through hole, and may be, for example, a concave bottomed hole along the surface of the spherical body 73 .

A fitting recess 63 is formed in the contact portion main body 61 on the connection side with the probe shaft portion 45 . A fitting convex portion 47 formed at the lower end of the probe shaft portion 45 is fitted into the fitting concave portion 63 together with an adhesive, so that the contact portion main body 61 and the probe shaft portion 45 are joined with the adhesive. Alternatively, the tip surface of the probe shaft portion 45 may be formed as a concave surface, and the fitting concave portion 63 and the fitting convex portion 47 may not be provided and both may be fixed with an adhesive.

The contact portion main body 61 is preferably made of, for example, a material that facilitates processing of the accommodating recess 65 and has rigidity capable of reliably supporting the spherical body 73, and is preferably made of, for example, ruby. In addition, metal materials such as stainless steel, copper, and aluminum may be used.

The sphere 73 preferably contains one selected from the group consisting of ruby, sapphire, diamond, ceramics, and cemented carbide. By using such a material with high hardness, it is possible to prevent damage due to contact with the workpiece W. In addition, the materials described above can be processed with high accuracy by laser, and are less subject to size restrictions than other machining methods. Therefore, even if the sphere 73 has a very small size, it can be processed with high accuracy. In particular, if the ruby sphere 73 is used for the ruby contact portion main body 61, the linear expansion coefficients of both are equal, so that it is less likely to be affected by thermal strain due to temperature changes after bonding. In addition, since the sphere 73 and the contact portion main body 61 undergo the same dimensional change due to the measured pressure, the dimensional stability is enhanced.

(Coordinate measurement procedure)
Next, a procedure for coordinate measurement of the work W by the coordinate measuring apparatus 100 will be described.
FIG. 5 is an explanatory diagram showing how the coordinates of the workpiece W are measured by the contact probe 41. As shown in FIG. FIG. 6 is an explanatory diagram schematically showing the operation of the contact probe 41. As shown in FIG.

The coordinate measuring apparatus 100 detects the position by bringing the contact portion 43 of the contact probe 41 into contact with the surface of the workpiece W, as shown in FIG. The workpiece W shown here is, for example, an outer ring that constitutes a small-diameter ball bearing (miniature bearing). The inner peripheral surface of the workpiece W is formed with a raceway groove G in which the rolling elements are arranged so as to be able to roll.

For example, when measuring the dimensions and shape of the raceway groove G of the workpiece W, any one of the projections 71A, 71B, 71C, and 71D of the contact portion 43 of the contact probe 41 is brought into contact with the inner surface of the raceway groove G. Specifically, as shown in FIG. 6, the contact probe 41 having the contact portion 43 arranged at the inner center position (origin position) O of the fixed workpiece W is moved in the -X direction (left side in FIG. 6). , and the projection 71B is brought into contact with the bottom of the raceway groove G of the work W to detect the position P1 (position of 270° in the circumferential direction of the work W). Next, the contact probe 41 is moved in the +X direction (right side in FIG. 6), and the projection 71D on the opposite side of the projection 71B is brought into contact with the bottom of the raceway groove G of the work W to position P2 (circumferential direction of the work W). 90° position). Further, the contact probe 41 is returned to the origin position O and moved in the +Y direction (upper side in FIG. 6) to bring the other projection 71C of the contact portion 43 into contact with the bottom of the raceway groove G of the workpiece W to position P3 (workpiece 0° position in the circumferential direction of W) is detected. After that, the contact probe 41 is moved in the -Y direction (lower side in FIG. 6), and the projection 71A on the opposite side of the projection 71C is brought into contact with the bottom of the raceway groove G of the work W to position P4 (the circumference of the work W). direction 180° position) is detected. Then, based on these measured positions P1 to P4, the dimensions of the workpiece W such as the inner diameter and eccentricity of the raceway groove G, and various shape information are calculated. The detection order in the above example is an example, and is not limited to this. For example, when measuring the roundness as the shape information of the work W, the work W is rotated while one of the projections 71A, 71B, 71C, and 71D is brought into contact with the raceway groove G.

(Dimensions of each part of the contact probe)
Next, the dimensions of each part of the contact probe 41 will be described.
FIG. 7 is a partially enlarged cross-sectional view of the work W in the axial direction, showing the dimensions of the contact portion 43 of the contact probe 41 and the work W. As shown in FIG. FIG. 8 is a partially enlarged plan view of the workpiece W shown in FIG. 7 viewed from above in the axial direction.

As shown in FIGS. 7 and 8, the outer diameter of the probe shaft portion 45 is d, and the diameter of the outer peripheral edge of the contact portion main body 61 in a cross section (XY plane in FIG. 8) orthogonal to the longitudinal direction of the probe shaft portion 45 is is D _B and the diameter of the sphere 73 of the protrusion 71 is D _S. At this time, the contact probe 41 satisfies the following relational expressions (1) to (4). (In formulas (3) and (4), this is a ratio with D _S =1.)

D _S <D _B (1)
d ≤ D _B (2)
D _S :D _B =1:2 to 4 (3)
d:D _B =2 to 3:3 (4)

For example, the outer diameter d of the probe shaft portion 45 is 0.4 to 0.6 mm. The diameter D _B of the outer peripheral edge of the contact portion main body 61 is 0.4 to 1.2 mm, preferably 0.6 mm. The diameter D _S of the sphere 73 is 0.1-0.3 mm, preferably 0.2 mm.

In the above example, the contact portion main body 61 and the projections 71A, 71B, 71C, and 71D are described as spherical bodies, but they may be other than spherical bodies. In that case, the curvature radius _rS of the cross-sectional shape of the tips of the projections 71A, 71B, 71C, and 71D (the cross-sectional shape including the longitudinal center line of the probe shaft portion 45) is the cross-sectional shape of the outer peripheral edge of the contact portion main body 61 (the probe (cross-sectional shape including the longitudinal center line of the shaft portion 45) is made smaller than the curvature radius _rB . Specifically, while the radius of curvature r 2 _B at the outer peripheral edge of the contact portion main body 61 is 0.2 to 0.6 mm, the radius of curvature r _{2 S} at the tip of the projection 71 is 0.05 to 0.05 mm. Make it 15 mm.

The raceway groove G of the workpiece W shown in FIG. 7 has a radial groove depth D _G , an axial cross-sectional curvature radius r _G , and an axial groove width W _G . The radius of curvature in the circumferential direction of the groove bottom of the groove G is _rR . On the other hand, in the contact portion 43 of the contact probe 41, the protrusion 71B (the same applies to the other protrusions 71A, 71C, and 71D) protrudes from the contact portion main body 61 so as to be larger than the depth DG of the raceway groove _G. , the radius of curvature _rS of the tip of the projection 71B is smaller than the radius of curvature rG of the raceway groove _G , and the maximum diameter of the projection 71B viewed from the outside in the radial direction (the radial direction of the workpiece W) is greater than the groove width WG of the raceway groove _G. is preferably small. Furthermore, it is preferable that the radius of curvature _rB of the outer peripheral edge of the contact _portion main body 61 shown in FIG.

As a result, the contact portion main body 61 and the contact portion 43 having the protrusions 71A, 71B, 71C, and 71D can reach the groove bottom of the raceway groove G without interfering with the edge of the raceway groove G. It becomes possible to make point contact with the groove bottom.

Further, in the bearing ring of the work W of this configuration, when the width of the work W in the axial direction (Z-axis direction) is B, the position of 1/2 of the width B becomes the axial center position of the raceway groove.
In the horizontally arranged workpiece W, the height hs from the lower end of the contact portion main body 61 to the stage surface 13 is greater than 0 and the projection 71B is in contact with the groove bottom at the axial center position of the raceway groove. It is preferably larger than the radius of 71B (as well as 71A, 71C and 71D). According to this, the projection 71B can contact the groove bottom at the center position of the track groove G in the axial direction without the contact portion 43 interfering with the stage surface 13 .

(Effect of contact probe)
In the contact probe 41 of this configuration, the curvature radius r _S of the cross-sectional shape including the longitudinal center line of the probe shaft portion 45 at the tips of the protrusions 71A, 71B, 71C, and 71D is It is smaller than the curvature radius r _B of the cross-sectional shape including the center line. As a result, the protrusions 71A, 71B, 71C, and 71D having a radius of curvature smaller than that of the contact portion main body 61 can be used even in narrow areas where the diameter of the contact portion main body 61 equivalent to the size of the conventional tip ball cannot be inserted. If so, it can be inserted. As a result, even in a narrow portion such as the raceway groove G, the tip of the protrusion can be brought into contact with the groove bottom, and the coordinates can be measured. Further, since the outer peripheral edge of the contact portion main body 61 is annular, it does not interfere with the workpiece W, and the measurable range can be expanded.

By using a holder of an appropriate size, the contact probe 41 of this configuration can be used as it is in a measuring device for measuring precise dimensions and shapes other than a coordinate measuring device. Therefore, it is possible to measure the size and shape of smaller workpieces and fine unevenness by simply using the existing measuring device and replacing only the probe. Therefore, the contact probe 41 having this configuration can be suitably applied to the measurement of extremely small bearings.

Moreover, since the protrusions 71A, 71B, 71C, and 71D of this configuration are configured by the spherical bodies 73, their contact with the work is stabilized. Moreover, if the projections 71 are spherical, even the micro-sized projections 71 can be formed without complicating the processing. The sphere 73 does not have to be a perfect sphere, and if the amount of protrusion is known, it is possible to easily secure the detection position accuracy by performing correction (calibration) on the side of the coordinate measuring apparatus. Therefore, by manufacturing a sphere by various known methods and attaching the obtained sphere to the contact portion main body 61, for example, machining is performed to form the protrusions 71A, 71B, 71C, and 71D by shaving or the like. In comparison, the manufacturing process is not complicated, and the projections can be formed at low cost.

In addition, since four projections 71A, 71B, 71C, and 71D are arranged on the outer periphery of the contact portion main body 61 at equal intervals in the circumferential direction around the axis of the probe shaft portion 45, the contact probe 41 can be held in the same posture. Can move in 4 directions. As a result, it is possible to measure the ring-shaped workpiece W at four different points in the circumferential direction. The number of protrusions 71A, 71B, 71C, and 71D can be arbitrarily set according to the number of measurement points on the workpiece.

In the above-described embodiment, the four protrusions 71A, 71B, 71C, and 71D are provided on the contact portion main body 61, but the contact portion main body 61 may be provided with at least one protrusion.
9A and 9B are bottom views of the contact probe 41 viewed from below in the axial direction.
As in the contact portion 43A shown in FIG. 9A, a pair of projections 71 may be provided on the contact portion body 61 at 180° intervals in the circumferential direction, and the contact portion 43B shown in FIG. , three protrusions 71 may be provided at intervals of 120° in the circumferential direction.

When two protrusions 71 are provided on the contact portion main body 61, for example, the contact probe 41 is moved in a uniaxial direction so that each protrusion 71 is positioned at two opposing locations on the inner periphery of the annular workpiece W or at two locations on the outer periphery. can be brought into contact with each other to measure the inner or outer peripheral dimension of the work W, and various shape information can be extracted from these dimensions. Further, when three protrusions 71 are provided on the contact portion main body 61, for example, the corresponding protrusions 71 are brought into contact with the respective sides of the inner and outer peripheries of the workpiece W, which is triangular in plan view, so that the inner periphery of the workpiece W is Circumferential dimensions, perimeter dimensions, and shapes can be measured.

Next, a modification of the above contact probe will be described.
<First modification>
FIG. 10 is a perspective view of the contact portion 43C in the first modified example of the contact probe.
In the first modified example, a protrusion 71E that protrudes along the longitudinal direction of the probe shaft portion 45 is arranged on the side of the contact portion main body 61 opposite to the mounting side of the probe shaft portion 45 . In other words, the contact portion main body 61 has four projections 71A, 71B, 71C, and 71D provided at equal intervals in the circumferential direction around the central axis of the probe shaft portion 45, and also projections on the lower portion of the contact portion main body 61. 71E is provided.

According to this configuration, by moving the contact probe 41 downward in the longitudinal direction of the probe shaft portion 45 and abutting the projection 71E against the work W, the upper portion of the work W including a narrow portion such as a minute groove can be moved. Dimensions and shapes can be easily measured. This allows measurements in all driving directions of the coordinate measuring device.

<Second modification>
FIG. 11 is a perspective view of the contact portion 43D in the second modified example of the contact probe.
In the second modification, the protrusion 71F provided on the contact portion main body 61 is formed in a tapered needle shape (conical shape). According to this configuration, the tip of the protrusion 71F can be reliably brought into point contact with the workpiece W, and the position can be detected with high accuracy.

<Second configuration example>
Next, a configuration in which the contact-type probe having the above configuration is applied to an electric micrometer as a coordinate measuring device will be described.
FIG. 12 is an explanatory view showing how the contact probe 41A for the second configuration example is attached to the electric micrometer 75 and the measurement is performed.

In this configuration, the contact probe 41A is attached to the probe support portion 75a of the electric micrometer 75. As shown in FIG. According to this configuration, when measuring a narrow portion such as a narrow groove of the workpiece W, the protrusion 71 provided on the contact portion 43 at the tip of the probe shaft portion 45A is inserted into the narrow portion, and the tip of the protrusion 71 is inserted into the narrow portion. position can be contacted. This enables the measurement by the electric micrometer 75 even in a narrow space.

<Third configuration example>
Next, a configuration in which the contact-type probe having the above configuration is applied to a dial gauge as a coordinate measuring device will be described.
FIG. 13 is an explanatory view showing how the contact probe 41B for the third configuration example is attached to the dial gauge 77 for measurement.
In this configuration, the contact probe 41B is attached to the probe support portion of the dial gauge 77. As shown in FIG. In this configuration, a protrusion 71 protruding in the longitudinal direction of the probe shaft portion 45B is provided on the side of the contact portion main body 61 opposite to the probe shaft portion 45B side. The protrusion 71 is inserted into a narrow portion such as a narrow groove of the work W, and the tip of the protrusion 71 is brought into contact with a target position. As a result, measurement by the dial gauge 77 is possible even in a narrow space.

In the measurement by the dial gauge 77 shown in FIG. 13, the workpiece W is the inner ring of the bearing, and the diameter of the raceway groove G formed on the outer peripheral surface of the inner ring is measured. One diametrical end of the raceway groove G is brought into contact with the protrusion 71 provided on the contact portion 43 on the fixed side, and the other diametrical end is brought into contact with the protrusion 71 provided on the contact portion 43 of the contact probe 41B. Then, the diameter Da of the raceway groove G of the work W is obtained by comparing the measured value of the work W with the measured value (reference dimension) of the master gauge which has been measured in advance. This makes it possible to easily measure the dimensions of confined spaces that have been difficult to measure in the past, reducing the number of man-hours for measurement and shortening the takt time.

<Fourth configuration example>
Next, a fourth configuration example of the contact probe will be described.
FIG. 14 is a schematic perspective view of a contact probe 41C of a fourth configuration example.
A contact probe 41C of this configuration has a probe shaft portion 45C and a plurality of contact portions 43E. The probe shaft portion 45C includes a plurality of support shafts 81A to 81E and a main shaft 83 that supports the plurality of support shafts 81A to 81E in different directions. A contact portion 43E is supported at the tip of each of the support shafts 81A to 81E. The support shafts 81A to 81E serve as branch shafts from the main shaft 83 and extend radially from the tip 83a of the main shaft 83. As shown in FIG.

A terminal 85 is fixed to the tip 83a of the main shaft 83, and five support shafts 81A to 81E are supported by the terminal 85 in different directions. The support shafts 81A to 81E may be directly connected to the main shaft 83 instead of being connected to the main shaft 83 via the terminal 85. FIG.

The support shafts 81A to 81E are arranged along three mutually orthogonal directions. That is, within a plane that includes the tip 83a of the main shaft 83 and is perpendicular to the longitudinal direction of the main shaft 83, the first support shaft 81A and the second support shaft 81B are arranged in opposite directions along the first imaginary straight line L1 that passes through the tip of the main shaft 83. oriented and supported by the main shaft 83 . In the above-described plane, the third support shaft 81C and the fourth support shaft 81D are supported by the main shaft 83 in opposite directions along a second imaginary straight line L2 perpendicular to the first imaginary straight line L1. A fifth support shaft 81E is supported by the distal end 83a of the main shaft 83 along the longitudinal direction of the main shaft 83 on the side opposite to the main shaft.

When the contact probe 41C of this configuration is attached to the probe support portion 29 of the coordinate measuring apparatus 100 shown in FIG. direction, Y direction, and Z direction.

15 is an enlarged view of the A portion of the contact probe 41C shown in FIG. 14. FIG.
A contact portion 43E is fixed to the tip of the first support shaft 81A (same for the other support shafts 81B to 81E). The contact portion 43</b>E has a contact portion main body 61 and a projection 71 . The protrusion 71 protrudes radially outward along the longitudinal direction of the first support shaft 81A from the outer peripheral surface of the contact portion main body 61 on the opposite side of the first support shaft 81A (on the right side in FIG. 15). The attachment of the contact portion main body 61 to the first support shaft 81A and the attachment of the projection 71 to the contact portion main body 61 are performed by inserting the end portion of the first support shaft 81A into the accommodation recess formed on the contact portion main body 61 on the base end side. is inserted and adhered, and a spherical body that becomes the projection 71 is inserted into the housing recess of the contact portion main body 61 on the tip side and adhered. The accommodation recess may be a hole with a bottom, or may penetrate through the hole.

The dimensions and shapes of each part of the contact portion main body 61 and the projection 71 are the same as in the case of the contact probe 41 of the first configuration example shown in FIGS.

FIG. 16 is an explanatory diagram showing how the work W is measured using the contact probe 41C shown in FIG.
The workpiece W shown here is an inner ring of a rolling bearing. The first support shaft 81A of the contact probe 41C is brought closer to the raceway groove G in a direction perpendicular to the axial direction of the workpiece W, and the projection 71 is inserted into the raceway groove G. As shown in FIG. Then, the coordinates of the workpiece W are measured by bringing the projection 71 into contact with the bottom of the raceway groove G. As shown in FIG.

A typical three-dimensional measuring machine has a structure in which a contact probe can move in three mutually orthogonal directions. In one measurement of the work W, the work W is measured at the coordinate measurement point X1 by the contact portion 43E of the first support shaft 81A, the coordinate measurement point X2 by the contact portion 43E of the second support shaft 81B, and the contact of the third support shaft 81C. It is necessary to measure a coordinate measurement point Y1 by the portion 43E, a coordinate measurement point Y2 by the contact portion 43E of the fourth support shaft 81D, and a coordinate measurement point Z1 by the contact portion 43E of the fifth support shaft 81E five times in total.

According to the contact-type probe 41C of this configuration, dedicated probes (the first support shaft 81A to the fifth support shaft 81E) are arranged for each of the coordinate measurement points described above, so that the initial dimensions of the tip of the probe can be maintained for a long period of time. , the durability of the contact probe is improved. As a result, deterioration over time is suppressed, and high-precision measurement can always be performed.

The minimum size of the tip of the probe used in the conventional three-dimensional measuring machine is φ0.3 mm, but the diameter of the support shaft in that case is about φ0.2 mm, and the rigidity of the support shaft is insufficient. For this reason, it is almost impossible to search for the center position of the groove of the work or to trace it, and the support shaft will bend even if there is a slight impact or load. As a result, the required accuracy may not be obtained.

However, according to the contact probes 41A to 41C of the present configuration described above, a protrusion is provided on the outer periphery of the contact portion main body, and by bringing this protrusion into contact with the work, it is possible to measure a minute area. It is no longer necessary to make the diameter of the support shaft extremely small, the necessary rigidity is obtained, and the measurement accuracy can be improved.

The present invention is not limited to the above-described embodiments, and it is also possible for those skilled in the art to combine each configuration of the embodiments with each other, modify and apply based on the description of the specification and well-known technology. It is intended by the invention and falls within the scope for which protection is sought.

For example, in the above embodiment, the probe shaft portion 45 and the contact portion main body 61 are joined separately, but the probe shaft portion 45 and the contact portion main body 61 may be integrally formed.

As described above, this specification discloses the following matters.
(1) A contact probe comprising a probe shaft and a contact portion fixed to the probe shaft,
The probe shaft portion has at least one support shaft that supports the contact portion at its tip,
The contact portion is
a contact portion main body having a circular or elliptical cross-sectional shape along the longitudinal direction of the support shaft;
at least one protrusion provided on the outer periphery of the contact portion main body and protruding radially outward;
has
The curvature radius of the cross-sectional shape including the longitudinal center line of the support shaft at the tip of the protrusion is smaller than the curvature radius of the cross-sectional shape including the longitudinal center line at the outer peripheral edge of the contact portion main body.
Contact probe.
According to the contact probe of this configuration, by making the radius of curvature of the tip of the projection smaller than the radius of curvature of the outer peripheral edge of the contact portion main body, a narrow portion of the workpiece to be measured that cannot be contacted by the contact portion main body can be brought into contact with the tip of the projection. Further, since the cross-sectional shape of the contact portion main body is circular or elliptical, interference with the workpiece is less likely to occur, and the measurement movable range is widened.
For example, when measuring inside a minute groove formed in a workpiece, even if the contact part body cannot fit into the groove, the workpiece can be easily measured by inserting the projection protruding from the contact part body into the groove. can do

(2) The contact probe according to (1), wherein the projection is a sphere.
According to the contact-type probe of this configuration, minute protrusions can be formed at low cost by forming the protrusions from spherical bodies.

(3) the contact portion main body is formed with a housing recess into which the ball can be inserted;
The contact probe according to (2), wherein the spherical body is adhered by inserting half of the spherical body into the housing recess.
According to the contact probe of this configuration, half of the sphere is inserted into the housing recess, and the other half of the sphere protrudes radially outward from the main body of the contact portion to serve as a projection. On the side where the sphere is inserted into the housing recess, the equator of the maximum perimeter of the sphere is adhered to the housing recess, so the sphere can be fixed to the contact portion main body with high adhesive strength.

(4) The contact probe according to any one of (1) to (3), wherein the contact portion main body has a spherical outer peripheral surface.
According to the contact-type probe having this configuration, even if the main body of the contact portion has a very small size, it can be manufactured with high dimensional accuracy, and processing becomes easy even when the projection is provided.

(5) Any one of (1) to (4), wherein the protrusions are arranged at a plurality of locations on the outer periphery of the contact portion main body at equal intervals in the circumferential direction around the longitudinal axis of the probe shaft portion. The contact probe described in .
According to the contact-type probe having this configuration, for example, when there are two projections, the contact-type probe can be moved uniaxially to measure two points in the diameter direction of the ring-shaped workpiece. When there are four protrusions, four different points on the ring-shaped workpiece can be measured by moving the contact probe in four directions.

(6) The contact probe according to (5), further including a projection protruding in the longitudinal direction of the probe shaft on the opposite side of the probe shaft of the contact portion main body.
According to the contact-type probe having this configuration, the contact-type probe can be moved in the longitudinal direction of the probe shaft portion and brought into contact with the workpiece for coordinate measurement, thereby improving the degree of freedom in measurement.

(7) The probe shaft is
a plurality of the support shafts;
a main shaft supporting the plurality of support shafts in different directions at one end;
The contact probe according to any one of (1) to (4).
According to the contact-type probe having this configuration, by supporting the plurality of support shafts on the main shaft in different directions, it is possible to improve the degree of freedom in the movement direction in which the projection of the contact portion contacts the workpiece to be measured. In addition, since the protrusions that come into contact with the work are arranged at the distal end of the support shaft away from the main shaft, the protrusions can be easily brought into contact with narrow areas on the surface of the work, and the measurement target can be expanded.

(8) The plurality of support shafts are
A first support shaft and a second support supported by the main shaft in opposite directions along a first straight line passing through one end of the main shaft in a plane that includes the tip of the main shaft and is perpendicular to the longitudinal direction of the main shaft. an axis;
a third support shaft and a fourth support shaft supported by the main shaft in opposite directions along a second straight line orthogonal to the first straight line in the plane;
a fifth support shaft supported on the tip of the main shaft along the longitudinal direction of the main shaft on the side opposite to the main shaft;
The contact probe according to (7).
According to the contact probe of this configuration, the first support shaft and the second support shaft are arranged in opposite directions, and the third support shaft and the fourth support shaft are arranged in opposite directions perpendicular to the first support shaft and the second support shaft. and a fifth support shaft orthogonal to the first to fourth support shafts, so that measurement of the workpiece along the mutually orthogonal X-, Y-, and Z-axes can be performed at the contact portions of the corresponding support shafts. can be done individually. As a result, the durability of each support shaft is enhanced, enabling more accurate measurement.

(9) The contact probe according to (8), wherein the protrusion is arranged on the side opposite to the main shaft of the support shaft.
According to the contact-type probe having this configuration, since the projection is brought into contact with the workpiece along the axial direction of the support shaft, the support shaft can be restrained from bending, and the measurement accuracy can be improved.

(10) The contact probe according to any one of (1) to (9), wherein the protrusion includes one selected from the group consisting of ruby, sapphire, diamond, ceramic, and cemented carbide.
According to the contact-type probe having this configuration, by using a material with high hardness, it is possible to prevent damage due to contact with the workpiece. In addition, laser processing can be performed with high accuracy, and the size is less restricted than other machining methods. Therefore, even micro-sized spheres can be easily processed.

(11) The contact probe according to (10), wherein the contact portion main body and the projection are made of the same material.
According to the contact probe of this configuration, since the contact portion main body and the protrusion have the same thermal expansion coefficient and elastic coefficient, the dimensional changes due to thermal expansion and measurement pressure are the same, and the dimensional stability is improved.

(12) The contact probe according to any one of (1) to (11), wherein the tip of the projection has a radius of curvature of 0.05 to 0.15 mm.
According to the contact-type probe of this configuration, even in a minute concave part where the contact part cannot enter,
A protrusion with a small radius of curvature can be inserted, and the range of application of coordinate measurement can be expanded.

(13) the contact probe according to any one of (1) to (12);
and a probe support that supports the contact probe,
A coordinate measuring apparatus for measuring the coordinates of the work by relatively scanning the work while the protrusion provided on the contact portion of the contact probe is in contact with the work and measuring the position of the contact probe.
According to the coordinate measuring apparatus having this configuration, the shape of even the narrow portion can be measured with high accuracy by bringing the protrusion of the contact portion into contact with the inside of the narrow portion formed in the work. Further, by mounting the contact-type probe of this configuration on the probe supporting portion, it becomes possible to measure the position of a narrow space, which has been difficult to measure even with an existing measuring device.

29 probe support part 41, 41A, 41B, 41C contact probe 43, 43A, 43B, 43C, 43D, 43E contact part 45 probe shaft part (support shaft)
61 contact portion main body 65 accommodation recess 71, 71A, 71B, 71C, 71D, 71E, 71F protrusion 73 sphere 75 electric micrometer 77 dial gauge 81A first support shaft (support shaft)
81B Second support shaft (support shaft)
81C third support shaft (support shaft)
81D Fourth support shaft (support shaft)
81E fifth support shaft (support shaft)
83 Spindle 100 Coordinate measuring device rs Curvature radius of projection rb Curvature radius of contact portion main body W Work

Claims (15)

A contact probe comprising a probe shaft and a contact portion fixed to the probe shaft,
The probe shaft portion has at least one support shaft that supports the contact portion at its tip,
The contact portion is
a contact portion main body having a circular or elliptical cross-sectional shape along the longitudinal direction of the support shaft;
at least one protrusion provided on the outer periphery of the contact portion main body and protruding radially outward;
has
The projection is composed of a sphere,
The radius of curvature of the cross-sectional shape including the longitudinal center line of the support shaft at the distal end of the projection is smaller than the radius of curvature of the cross-sectional shape including the longitudinal center line at the outer peripheral edge of the contact portion main body,
The contact portion main body is formed with a housing recess into which the ball can be inserted,
said sphere is glued by inserting half of said sphere into said receiving recess;
Contact probe. 2. The contact probe according to claim 1 , wherein the projections are arranged at a plurality of locations on the outer periphery of the contact portion main body at equal intervals in the circumferential direction around the longitudinal axis of the probe shaft portion. 3. The contact probe according to claim 2 , further comprising a projection projecting in the longitudinal direction of said probe shaft on the opposite side of said contact portion main body from said probe shaft. A contact probe comprising a probe shaft and a contact portion fixed to the probe shaft,
The probe shaft portion has at least one support shaft that supports the contact portion at its tip,
The contact portion is
a contact portion main body having a circular or elliptical cross-sectional shape along the longitudinal direction of the support shaft;
at least one protrusion provided on the outer periphery of the contact portion main body and protruding radially outward;
has
The radius of curvature of the cross-sectional shape including the longitudinal center line of the support shaft at the distal end of the projection is smaller than the radius of curvature of the cross-sectional shape including the longitudinal center line at the outer peripheral edge of the contact portion main body,
The protrusions are arranged at a plurality of locations on the outer periphery of the contact portion main body at equal intervals in the circumferential direction centering on the longitudinal axis of the probe shaft portion.
Contact probe. 5. The contact probe according to claim 4 , further comprising a projection projecting in the longitudinal direction of said probe shaft on the opposite side of said contact portion main body from said probe shaft. 6. The contact probe according to claim 4 , wherein said projection is a sphere. The contact probe according to any one of claims 1 to 6 , wherein the contact portion main body has a spherical outer peripheral surface. The probe shaft is
a plurality of the support shafts;
a main shaft supporting the plurality of support shafts in different directions at one end;
The contact probe according to claim 1, comprising: 9. The contact probe according to claim 8, wherein the contact portion main body has a spherical outer peripheral surface. The plurality of support shafts are
A first support shaft and a second support supported by the main shaft in opposite directions along a first straight line passing through one end of the main shaft in a plane that includes the tip of the main shaft and is perpendicular to the longitudinal direction of the main shaft. an axis;
a third support shaft and a fourth support shaft supported by the main shaft in opposite directions along a second straight line orthogonal to the first straight line in the plane;
10. The contact probe according to claim 8 , further comprising a fifth support shaft supported on the opposite side of the main shaft along the longitudinal direction of the main shaft at the tip of the main shaft. 11. The contact probe according to claim 10 , wherein the protrusion is arranged on the side opposite to the main shaft of the support shaft. The contact probe according to any one of claims 1 to 11 , wherein the protrusion includes one selected from the group consisting of ruby, sapphire, diamond, ceramic, and cemented carbide. 13. The contact probe according to claim 12 , wherein the contact portion main body and the projection are made of the same material. The contact probe according to any one of claims 1 to 13 , wherein the tip of the projection has a radius of curvature of 0.05 to 0.15 mm. A contact probe according to any one of claims 1 to 14 ;
and a probe support that supports the contact probe,
A coordinate measuring apparatus for measuring the coordinates of the work by relatively scanning the work while the protrusion provided on the contact portion of the contact probe is in contact with the work and measuring the position of the contact probe.

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