Measuring tool

Abstract

A probe according to the present invention extends along an axis. The probe has a base part, a first intermediate part, and a second intermediate part. The first intermediate part is continuous with the base part. The first intermediate part is positioned between a front end of the probe and the base part. The second intermediate part is continuous with the first intermediate part. The second intermediate part is positioned between the first intermediate part and the front end. When an angle formed by the axis and a tangent line of a surface of the probe in a cross section including the axis is defined as an inclination angle, the inclination angle of the first intermediate part is larger than the inclination angle of the base part. The inclination angle of the second intermediate part is equal to or less than the inclination angle of the first intermediate part.

Description

Measuring tool

[0001] The present disclosure relates to a measuring tool.

[0002] Japanese Unexamined Patent Publication No. 2021-032688 (Patent Document 1) describes a shape measuring apparatus that measures the surface texture of an object to be measured by moving a stylus while keeping the stylus in contact with the object.

[0003] Japanese Unexamined Patent Publication No. 2021-032688

[0004] The measuring tool according to the present disclosure includes a measuring element. The measuring element extends along an axis. The measuring element has a base portion, a first intermediate portion, and a second intermediate portion. The first intermediate portion is connected to the base portion. The first intermediate portion is located between the front end of the measuring element and the base portion. The second intermediate portion is connected to the first intermediate portion. The second intermediate portion is located between the first intermediate portion and the front end. In a portion of the measuring element including a region from the front end to the first intermediate portion, a diameter at a first measurement position is equal to or larger than a diameter at a second measurement position located between the first measurement position and the front end in the direction in which the axis extends. When an angle formed between a tangent to a surface of the measuring element and the axis in a cross section including the axis is defined as an inclination angle, the inclination angle of the first intermediate portion is larger than the inclination angle of the base portion. The inclination angle of the second intermediate portion is equal to or smaller than the inclination angle of the first intermediate portion.

[0005] Figure 1 is a schematic side view showing the configuration of the measuring tool according to the first embodiment. Figure 2 is an enlarged schematic cross-sectional view showing the configuration of the measuring element according to the first embodiment. Figure 3 is a schematic diagram for explaining the inclination angle of the measuring element according to the first embodiment. Figure 4 is a schematic cross-sectional view taken along line IV-IV in Figure 2. Figure 5 is a schematic diagram for explaining a step of forming a constriction in the measuring element. Figure 6 is an enlarged schematic cross-sectional view showing the configuration of the measuring element according to the second embodiment. Figure 7 is a schematic diagram for explaining the inclination angle of the measuring element according to the second embodiment. Figure 8 is a schematic diagram for explaining the measurement of surface texture of an object to be measured using a measuring element according to a comparative example. Figure 9 is a schematic diagram for explaining the measurement of surface texture of an object to be measured using a measuring element according to the present embodiment.

[0006] [Problem to be Solved by the Present Disclosure] The stylus of the shape measuring apparatus described in Patent Document 1 has a conical tip portion. When a stylus having a conical tip portion is used, measurement accuracy may be degraded.

[0007] The purpose of this disclosure is to provide a measuring tool capable of improving measurement accuracy. [Effects of this disclosure] According to this disclosure, a measuring tool capable of improving measurement accuracy can be provided.

[0008] [Outline of Embodiments] First, an outline of the embodiments of this disclosure will be described.

[0009] (1) The measuring tool according to the present disclosure has a measuring probe. The measuring probe extends along an axis. The measuring probe has a base, a first intermediate portion, and a second intermediate portion. The first intermediate portion is connected to the base. The first intermediate portion is located between the front end of the measuring probe and the base. The second intermediate portion is connected to the first intermediate portion. The second intermediate portion is located between the first intermediate portion and the front end. In the portion of the measuring probe including the front end to the first intermediate portion, the diameter at the first measuring position is greater than or equal to the diameter at the second measuring position located between the first measuring position and the front end in the direction in which the axis extends. When the angle between the tangent to the surface of the measuring probe in a cross-section including the axis and the axis is defined as the inclination angle, the inclination angle of the first intermediate portion is greater than the inclination angle of the base. The inclination angle of the second intermediate portion is less than or equal to the inclination angle of the first intermediate portion. This makes it possible to improve the measurement accuracy.

[0010] (2) In the measuring tool described in (1) above, the second intermediate portion may have a portion with a smaller inclination angle than the base portion. This prevents an excessive decrease in the strength of the measuring probe.

[0011] (3) In the case of the measuring tool according to (1) or (2) above, the surface of the base may be straight in cross-section. The surfaces of the first intermediate part and the second intermediate part may be concave in the direction toward the axis from a virtual straight line with respect to a virtual straight line that overlaps the surface of the base. This makes it possible to improve measurement accuracy while preventing an excessive decrease in the strength of the measuring probe.

[0012] (4) In the measuring tool described in (3) above, the measuring probe may have a tip. The tip may form a front end. In cross-section, the surface of the tip may be arc-shaped. The distance between the front end and the second intermediate portion in the direction in which the axis extends may be greater than or equal to the value obtained by multiplying the radius of the tip in cross-section by tan 30°, and less than or equal to four times the radius of the tip in cross-section. This can effectively improve the measurement accuracy.

[0013] (5) In the measuring tool according to any of (1) to (4) above, the measuring probe may have a third intermediate portion. The third intermediate portion may be connected to the second intermediate portion. The third intermediate portion may be located between the second intermediate portion and the front end. In cross-section, the surface of the third intermediate portion may be straight. The inclination angle of the third intermediate portion may be greater than the inclination angle of the second intermediate portion. This makes it possible to improve the strength of the portion of the measuring probe closer to the front end.

[0014] (6) The measuring tool according to any of (1) to (5) above may further have a support portion. The support portion may be joined to the measuring probe at its rear end. When viewed perpendicular to the axis, the width of the measuring probe at the joint surface between the measuring probe and the support portion may be 0.1 mm or more and 10 mm or less. This prevents chipping or the like from occurring in the part of the measuring tool near the joint surface.

[0015] (7) In the case of the measuring tool according to any of (1) to (6) above, the value obtained by subtracting the inclination angle of the base from the maximum inclination angle at the first intermediate part may be 0.01° or more and 5° or less. This makes it possible to improve the measurement accuracy while preventing an excessive decrease in the strength of the measuring probe.

[0016] (8) In the case of the measuring tool according to (1) or (2) above, the portion of the measuring probe including the front end to the first intermediate portion may be located between a virtual straight line overlapping the surface of the base and the axis in the cross-section. This can effectively improve the measurement accuracy.

[0017] (9) In the case of a measuring tool according to any of (1) to (8) above, the measuring probe may be formed from a hard material whose main component is one of diamond, cemented carbide, ruby, sapphire, and silicon carbide. This can improve the strength of the measuring probe.

[0018] [Details of Embodiments] The details of embodiments of the present disclosure (hereinafter also referred to as these embodiments) will be described below with reference to the drawings. In the following drawings, identical or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0019] (First Embodiment) First, the configuration of the measuring tool 100 according to the first embodiment will be described. Figure 1 is a schematic side view showing the configuration of the measuring tool 100 according to the first embodiment.

[0020] The measuring tool 100 mainly consists of a measuring probe 1 and a support part 2. The measuring tool 100 is used as a stylus for measuring devices such as a three-dimensional shape measuring device and a surface texture measuring device. The measuring probe 1 comes into contact with the object to be measured. The support part 2 is the part that is attached to the measuring device.

[0021] The measuring probe 1 extends along axis X. The central axis of the measuring probe 1 may coincide with axis X. Figure 1 shows the configuration of the measuring tool 100 as viewed perpendicular to axis X.

[0022] The measuring probe 1 has a front end 9 and a rear end 8. The front end 9 faces the object to be measured. In the direction in which the axis X extends (axial direction), the rear end 8 is opposite to the front end 9. In this specification, the direction parallel to the axis X and extending from the rear end 8 to the front end 9 is referred to as the forward direction.

[0023] At the rear end 8 of the measuring probe 1, the support portion 2 is joined to the measuring probe 1. When viewed perpendicular to the axis X, the width H of the measuring probe 1 at the joint surface 7 between the measuring probe 1 and the support portion 2 is 0.1 mm or more and 10 mm or less. The width H may be, for example, 0.2 mm or more, or 0.3 mm or more. The width H may be, for example, 5 mm or less, 3 mm or less, or 1 mm or less. The length L of the measuring probe 1 in the axial direction is, for example, 10 mm or less.

[0024] The measuring probe 1 is formed from a hard material whose main component is one of the following: diamond, cemented carbide, ruby, sapphire, and silicon carbide. In this disclosure, "main component" refers to the component that has the largest weight content among the constituent components, for example, a component with a content of 80% by weight or more.

[0025] Figure 2 is an enlarged schematic cross-sectional view showing the configuration of the measuring probe 1. The cross-section shown in Figure 2 is a cross-section that includes axis X and is parallel to the axial direction. In this specification, the cross-section shown in Figure 2 is referred to as the first cross-section C1. The region shown in Figure 2 corresponds to region II in Figure 1.

[0026] As shown in Figure 2, the measuring probe 1 has, for example, a base portion 10, a first intermediate portion 11, a second intermediate portion 12, a third intermediate portion 13, and a tip portion 19. The measuring probe 1 may consist of the base portion 10, the first intermediate portion 11, the second intermediate portion 12, the third intermediate portion 13, and the tip portion 19.

[0027] The base portion 10 forms the rear end 8 (see Figure 1). From another perspective, the base portion 10 is joined to the support portion 2 (see Figure 1). The shape of the base portion 10 is a frustoconical shape. In the first cross-section C1, the surface of the base portion 10 is straight.

[0028] The first intermediate portion 11 is connected to the base portion 10. In the first cross-section C1, the first intermediate portion 11 is located in front of the base portion 10. From another point of view, the first intermediate portion 11 is located between the front end 9 and the base portion 10. In the first cross-section C1, the surface of the first intermediate portion 11 is curved. Specifically, in the first cross-section C1, the surface of the first intermediate portion 11 is curved radially inward. Radially inward means in a direction perpendicular to and toward the axis X.

[0029] The second intermediate section 12 is connected to the first intermediate section 11. The second intermediate section 12 is located in front of the first intermediate section 11. From another perspective, the second intermediate section 12 is located between the first intermediate section 11 and the front end 9. In the first cross-section C1, the surface of the second intermediate section 12 is, for example, curved. Specifically, in the first cross-section C1, the surface of the second intermediate section 12 is curved radially inward.

[0030] In the first intermediate section 11 and the second intermediate section 12, the measuring probe 1 is constricted. From another perspective, in the first cross-section C1, with respect to a virtual straight line 98 that overlaps the base 10, the surfaces of the first intermediate section 11 and the second intermediate section 12 are concave in the direction from the virtual straight line 98 toward the axis X. In other words, in the first cross-section C1, the surfaces of the first intermediate section 11 and the second intermediate section 12 form a concave curve in the direction from the virtual straight line 98 toward the axis X. In the first cross-section C1, the portion of the measuring probe 1 including the front end 9 to the first intermediate section 11 is located between the virtual straight line 98 and the axis X.

[0031] In the first cross-section C1, the angle formed by the two virtual straight lines 98 is the taper angle θ9 of the base 10. The taper angle θ9 is, for example, 30° or more and 120° or less. The taper angle θ9 may also be, for example, 60° or 90°.

[0032] The third intermediate section 13 is connected to the second intermediate section 12. The third intermediate section 13 is located in front of the second intermediate section 12. From another perspective, the third intermediate section 13 is located between the second intermediate section 12 and the front end 9. In the first cross-section C1, the surface of the third intermediate section 13 is straight.

[0033] The tip portion 19 is connected to, for example, the third intermediate portion 13. The tip portion 19 is located in front of the third intermediate portion 13. The tip portion 19 forms the front end 9. In the first cross-section C1, the surface of the tip portion 19 is arc-shaped. The apex of the surface of the tip portion 19 forms the front end 9. The radius of curvature of the surface of the tip portion 19 in the first cross-section C1 is referred to as the radius R of the tip portion 19. The radius R is, for example, 0.5 μm or more and 100 μm or less.

[0034] In the first cross-section C1, the boundary line between the base portion 10 and the first intermediate portion 11 is defined as the first boundary line B1. Similarly, in the first cross-section C1, the boundary lines between the first intermediate portion 11 and the second intermediate portion 12, the boundary line between the second intermediate portion 12 and the third intermediate portion 13, and the boundary line between the third intermediate portion 13 and the tip portion 19 are defined as the second boundary line B2, the third boundary line B3, and the fourth boundary line B4, respectively. Each of the first boundary line B1, the second boundary line B2, the third boundary line B3, and the fourth boundary line B4 may be perpendicular to the axis X, or may be inclined with respect to a direction perpendicular to the axis X.

[0035] The distance between the front end 9 and the base 10 in the axial direction (first distance E1) is, for example, 5 mm or less. The first distance E1 is the shortest distance between the first boundary line B1 and the front end 9 in the axial direction.

[0036] The distance between the front end 9 and the second intermediate portion 12 in the axial direction (second distance E2) is greater than or equal to the value obtained by multiplying the radius R of the tip portion 19 in the cross-section by tan 30°, and less than or equal to four times the radius R of the tip portion 19 in the cross-section. The second distance E2 may be, for example, less than or equal to three times the radius R, or less than or equal to two times the radius R. The second distance E2 is the shortest distance between the third boundary line B3 and the front end 9 in the axial direction.

[0037] <Angle of inclination> In this specification, the angle between the tangent line 99 to the surface of the measuring probe 1 in the first cross section C1 and the axis X is referred to as the angle of inclination. In Figure 2, as an example of the tangent line 99, the tangent line to the surface of the first intermediate portion 11 at the first boundary line B1 is shown. The angle θ between the tangent line 99 and the axis X is the angle of inclination. Note that the imaginary line 97 shown in Figure 2 is a line parallel to the axis X.

[0038] Figure 3 is a schematic diagram illustrating the inclination angle of the measuring probe 1 according to the first embodiment. In Figure 3, the vertical axis represents the inclination angle, and the horizontal axis represents the position in the axial direction. As shown in Figures 2 and 3, the inclination angle of the base 10 may be constant from the rear end 8 to the first boundary line B1. The inclination angle of the base 10 is set to a first inclination angle θ1. The first inclination angle θ1 is half of the taper angle θ9.

[0039] The inclination angle of the first intermediate section 11 is greater than the first inclination angle θ1. From another perspective, between the first boundary line B1 and the second boundary line B2, the inclination angle of the measuring probe 1 is greater than the first inclination angle θ1. The inclination angle of the first intermediate section 11 at the first boundary line B1 is greater than the inclination angle of the first intermediate section 11 at the second boundary line B2. For example, as you move away from the base 10 along the axis X, the inclination angle of the first intermediate section 11 decreases.

[0040] As shown in Figure 3, the maximum inclination angle at the first intermediate section 11 is the second inclination angle θ2. The second inclination angle θ2 is, for example, the inclination angle of the first intermediate section 11 at the first boundary line B1. The value obtained by subtracting the first inclination angle θ1 from the second inclination angle θ2 is between 0.01° and 5°. The value obtained by subtracting the first inclination angle θ1 from the second inclination angle θ2 may be, for example, 0.1° or more, 0.5° or more, or 1° or more. The value obtained by subtracting the first inclination angle θ1 from the second inclination angle θ2 may be, for example, 4° or less, 3° or less, or 2° or less.

[0041] The inclination angle of the second intermediate section 12 is, for example, less than or equal to the first inclination angle θ1. From another point of view, the inclination angle of the second intermediate section 12 is smaller than the inclination angle of the first intermediate section 11. In the measuring tool 100 according to the first embodiment, of the portion of the measuring probe 1 located between the first boundary line B1 and the third boundary line B3, the portion with an inclination angle greater than the first inclination angle θ1 is designated as the first intermediate section 11, and the portion with an inclination angle less than or equal to the first inclination angle θ1 is designated as the second intermediate section 12.

[0042] The inclination angle of the second intermediate portion 12 at the second boundary line B2 is greater than, for example, the inclination angle of the second intermediate portion 12 at the third boundary line B3. For example, as you move away from the first intermediate portion 11 along the axis X, the inclination angle of the second intermediate portion 12 decreases. The second intermediate portion 12 has a portion where the inclination angle is smaller than that of the base portion 10. For example, except at the second boundary line B2, the inclination angle of the second intermediate portion 12 is smaller than the first inclination angle θ1. The second intermediate portion 12 may also have a portion where the inclination angle is larger than that of the base portion 10.

[0043] The inclination angle of the third intermediate portion 13 may be constant from the third boundary line B3 to the fourth boundary line B4. The inclination angle of the third intermediate portion 13 is larger than, for example, the inclination angle of the second intermediate portion 12. Specifically, the inclination angle of the third intermediate portion 13 is larger than, for example, the maximum value of the inclination angle of the second intermediate portion 12. The inclination angle of the third intermediate portion 13 is larger than the first inclination angle θ1.

[0044] In the shape measurement of the measuring tool 100, a scanning electron microscope (SEM: Scanning Electron Microscope) is used. Specifically, in the shape measurement of the probe 1 such as the inclination angle, radius R, first length E1, and second length E2, an SEM image of the first cross section C1 is captured. The inclination angle is measured using the SEM image. When the shape of the probe 1 in a cross section perpendicular to the axis X is circular, the shape measurement of the probe 1 can be performed using an SEM image viewed in a direction perpendicular to the axis X without cutting the probe 1 to prepare a cross section.

[0045] It should be noted that in FIG. 3, the change rate of the inclination angle is constant from the first boundary line B1 to the third boundary line B3, but the change rate of the inclination angle does not have to be constant from the first boundary line B1 to the third boundary line B3.

[0046] <Diameter of Probe> FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 2. The cross section shown in FIG. 4 is a cross section perpendicular to the axis X. The cross section shown in FIG. 4 is defined as a second cross section C2. As shown in FIG. 4, the probe 1 has a circular shape in the second cross section C2. The maximum distance D between two points on the surface of the probe 1 in a direction perpendicular to the axis X is defined as the diameter of the probe 1.

[0047] As shown in FIGS. 1 and 2, the diameter of the base portion 10 decreases as moving away from the rear end 8 along the axis X. As shown in FIG. 2, the diameter of the portion of the probe 1 including from the front end 9 to the first intermediate portion 11 is equal to or less than the diameter of the base portion 10. Specifically, the diameter of the portion of the probe 1 located between the front end 9 and the first boundary line B1 is equal to or less than the minimum value of the diameter of the base portion 10. The minimum value of the diameter of the base portion 10 is the diameter of the base portion 10 at the first boundary line B1.

[0048] As shown in Fig. 2, in the portion of the measuring stylus 1 including from the front end 9 to the first intermediate portion 11, a first measurement position P1 and a second measurement position P2 are defined. The first measurement position P1 is any position between the front end 9 and the first boundary line B1 in the axial direction. The second measurement position P2 is a position between the first measurement position P1 and the front end 9.

[0049] In the portion of the measuring stylus 1 including from the front end 9 to the first intermediate portion 11, the diameter at the first measurement position P1 is not less than the diameter at the second measurement position P2. The diameter at the first measurement position P1 may be larger than the diameter at the second measurement position P2. From another point of view, as the distance from the base 10 increases, the diameter of the portion of the measuring stylus 1 including from the front end 9 to the first intermediate portion 11 may decrease.

[0050] The diameter of the first intermediate portion 11 at the first boundary line B1 is larger than the diameter of the second intermediate portion 12 at the third boundary line B3. As the distance from the base 10 increases, the diameters of the first intermediate portion 11 and the second intermediate portion 12 may decrease.

[0051] Note that the measuring stylus 1 of the measuring tool 100 according to the first embodiment does not need to include the third intermediate portion 13. The measuring stylus 1 may be composed of the base 10, the first intermediate portion 11, the second intermediate portion 12, and the tip portion 19. In this case, the tip portion 19 is connected to the second intermediate portion 12.

[0052] Next, a method for manufacturing the measuring tool 100 according to the first embodiment will be described. In the method for manufacturing the measuring tool 100, first, a part of the measuring stylus 1 and the support portion 2 is formed into a conical shape using a polishing disc or the like. The polishing disc is made of, for example, cast iron.

[0053] Next, a process is carried out to form a constriction in the measuring probe 1. Figure 5 is a schematic diagram illustrating the process of forming a constriction in the measuring probe 1. As shown in Figure 5, a part of the measuring probe 1 is inserted into the abrasive grain 5. The abrasive grain 5 contains, for example, diamond. The measuring probe 1 is polished by the measuring tool 100 rotating around axis X along arrow A1. During polishing, the measuring probe 1 is tilted along a direction perpendicular to axis X, as shown by arrow A2, thereby forming a constriction in the measuring probe 1. This forms the first intermediate portion 11 and the second intermediate portion 12 shown in Figure 2.

[0054] (Second Embodiment) Next, the configuration of the measuring tool 100 according to the second embodiment will be described. The measuring tool 100 according to the second embodiment differs from the measuring tool 100 according to the first embodiment mainly in that the inclination angle of the portion of the measuring probe 1 located between the first intermediate portion 11 and the front end 9 is greater than or equal to the first inclination angle θ1. In other respects, it is substantially the same as the measuring tool 100 according to the first embodiment. The following description will focus on the differences from the measuring tool 100 according to the first embodiment.

[0055] Figure 6 is an enlarged schematic cross-sectional view showing the configuration of the measuring probe 1 according to the second embodiment. As shown in Figure 6, the measuring probe 1 according to the second embodiment consists of a base portion 10, a first intermediate portion 11, a second intermediate portion 12, and a tip portion 19. In the first cross-section C1, the surface of the second intermediate portion 12 is straight. In the first cross-section C1, the boundary line between the second intermediate portion 12 and the tip portion 19 is defined as the fifth boundary line B5.

[0056] Figure 7 is a schematic diagram illustrating the inclination angle of the measuring probe according to the second embodiment. The graph shown in Figure 7 corresponds to the graph shown in Figure 3. As shown in Figure 7, the inclination angle of the second intermediate portion 12 may be constant from the second boundary line B2 to the fifth boundary line B5.

[0057] The inclination angle of the second intermediate section 12 is less than or equal to the inclination angle of the first intermediate section 11. Specifically, the inclination angle of the second intermediate section 12 may be the same as the minimum value of the inclination angle of the first intermediate section 11, or it may be smaller than the minimum value of the inclination angle of the first intermediate section 11. The inclination angle of the second intermediate section 12 may be greater than, for example, the first inclination angle θ1. The inclination angle of the second intermediate section 12 may also be less than or equal to the first inclination angle θ1. In Figure 7, the rate of change of the inclination angle is constant from the first boundary line B1 to the second boundary line B2, but the rate of change of the inclination angle is not necessarily constant from the first boundary line B1 to the second boundary line B2.

[0058] Next, the effects of the measuring tool 100 according to this embodiment will be described. In the method for measuring surface shape using the measuring tool 100, the surface roughness and shape of the surface of the object to be measured are measured by moving the measuring probe along the surface of the object to be measured while the measuring probe is in contact with the object to be measured. As shown in Figure 8, minute recesses 90 are formed on the surface of the object to be measured W. If the shape of the measuring probe 1 is conical, the side surface of the measuring probe 1 may interfere with the object to be measured W, preventing the measuring probe 1 from contacting the lowest point of the minute recesses 90. In this case, the measuring probe 1 cannot follow the surface of the object to be measured W, resulting in a decrease in measurement accuracy.

[0059] According to the measuring tool 100 of this embodiment, the measuring probe 1 has a base portion 10, a first intermediate portion 11, and a second intermediate portion 12. The inclination angle of the first intermediate portion 11 is greater than the inclination angle of the base portion 10. Therefore, compared to the case where the shape of the measuring probe 1 is conical, the diameter of the measuring probe 1 is smaller at the first intermediate portion 11. As a result, as shown in Figure 9, it is possible to prevent the side surface of the measuring probe 1 from interfering with the object to be measured W. Consequently, the measuring probe 1 is more likely to contact the lowest point of the minute recess 90. As a result, measurement accuracy can be improved.

[0060] In the measuring tool 100 according to this embodiment, the second intermediate portion 12 is located between the first intermediate portion 11 and the front end 9. The inclination angle of the second intermediate portion 12 is less than or equal to the inclination angle of the first intermediate portion 11. Therefore, the diameter of the measuring probe 1 is prevented from becoming excessively small in the second intermediate portion 12. From another point of view, the diameter of the portion of the measuring probe 1 located between the first intermediate portion 11 and the front end 9 is prevented from becoming excessively small. Accordingly, an excessive decrease in the strength of the measuring probe 1 can be prevented.

[0061] According to the measuring tool 100 of this embodiment, the second intermediate portion 12 has a portion where the inclination angle is smaller than that of the base portion 10. Therefore, the diameter of the measuring probe 1 is prevented from becoming excessively small in the second intermediate portion 12. Consequently, the strength of the measuring probe 1 is prevented from being excessively reduced.

[0062] According to the measuring tool 100 of this embodiment, in the first cross-section C1, the surfaces of the first intermediate portion 11 and the second intermediate portion 12 are recessed in the direction toward the axis X from the virtual straight line 98 that overlaps the surface of the base portion 10. Therefore, the inclination angle of the first intermediate portion 11 and the second intermediate portion 12 decreases as they move away from the base portion 10. This prevents the side surface of the measuring probe 1 from interfering with the object to be measured W, while also preventing an excessive decrease in the strength of the measuring probe 1.

[0063] According to the measuring tool 100 of this embodiment, the measuring probe 1 has a tip portion 19 that forms the front end 9. In the first cross-section C1, the surface of the tip portion 19 is arc-shaped. The distance between the front end 9 and the second intermediate portion 12 in the axial direction (second distance E2) is four times or less the radius of the tip portion 19 in the first cross-section C1. As described above, the second intermediate portion 12 has a portion with a smaller inclination angle than the base portion 10. Therefore, the diameter of the second intermediate portion 12 is prevented from becoming excessively large compared to the tip portion 19. Accordingly, according to the measuring tool 100 of this embodiment, the distance between the second intermediate portion 12, whose diameter is prevented from becoming excessively large, and the front end 9 is sufficiently short. This effectively prevents the side surface of the measuring probe 1 from interfering with the object to be measured W.

[0064] According to the measuring tool 100 of this embodiment, the measuring probe 1 has a third intermediate portion 13 that is connected to the second intermediate portion 12 and located between the second intermediate portion 12 and the front end 9. In the first cross-section C1, the surface of the third intermediate portion 13 is straight. The inclination angle of the third intermediate portion 13 is greater than the inclination angle of the second intermediate portion 12. As a result, the diameter of the measuring probe 1 is relatively increased in the portion of the measuring probe 1 closest to the front end 9. Therefore, the strength of the portion of the measuring probe 1 closest to the front end 9 can be improved.

[0065] The measuring tool 100 according to this embodiment has a support portion 2. The support portion 2 is joined to the measuring probe 1 at its rear end 8. When viewed perpendicular to the axis X, the width H of the measuring probe at the joint surface 7 between the measuring probe 1 and the support portion 2 is 0.1 mm or more. This prevents the joint surface between the measuring probe 1 and the support portion 2 from becoming excessively narrow. Therefore, even when a bending moment is applied to the joint surface due to a force being applied to the front end 9 of the measuring probe 1, it is possible to prevent chipping or other damage to the part of the measuring tool 100 near the joint surface 7.

[0066] According to the measuring tool 100 of this embodiment, the value obtained by subtracting the inclination angle of the base portion 10 from the maximum inclination angle of the first intermediate portion 11 is 0.01° or more. As a result, the diameter of the measuring probe 1 is sufficiently reduced in the first intermediate portion 11. Therefore, interference between the side surface of the measuring probe 1 and the object to be measured W can be effectively prevented. According to the measuring tool 100 of this embodiment, the value obtained by subtracting the inclination angle of the base portion 10 from the maximum inclination angle of the first intermediate portion 11 is 5° or less. As a result, the diameter of the measuring probe 1 in the first intermediate portion 11 is prevented from becoming excessively small. Therefore, an excessive decrease in the strength of the measuring probe 1 can be prevented.

[0067] According to the measuring tool 100 of this embodiment, in the first cross-section C1, the portion of the measuring probe including the front end 9 to the first intermediate portion 11 is located between a virtual straight line 98 that overlaps the surface of the base portion 10 and the axis X. Therefore, compared to the case where the shape of the measuring probe 1 is conical, interference between the side surface of the measuring probe 1 and the object to be measured W can be effectively prevented.

[0068] According to the measuring tool 100 of this embodiment, the measuring probe 1 is formed from a hard material whose main component is one of diamond, cemented carbide, ruby, sapphire, and silicon carbide. This makes it possible to improve the strength of the measuring probe 1.

[0069] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description and is intended to include the meaning of equivalents of the claims and all modifications within the scope.

[0070] 1 measuring element, 2 supporting part, 5 abrasive grain, 7 joint surface, 8 rear end, 9 front end, 10 base, 11 first intermediate part, 12 second intermediate part, 13 third intermediate part, 19 tip part, 90 recess, 97 imaginary line, 98 imaginary straight line, 99 tangent, 100 measuring tool, A1, A2 arrow, B1 first boundary line, B2 2nd boundary line, B3 3rd boundary line, B4 4th boundary line, B5 5th boundary line, C1 1st cross section, C2 2nd cross section, D maximum distance, E1 1st distance, E2 2nd distance, H width, P1 1st measurement position, P2 2nd measurement position, R radius, W object to be measured, X axis, θ angle, θ1 1st inclination angle, θ2 2nd inclination angle, θ9 taper angle.

Claims

1. A measuring tool comprising a measuring probe extending along an axis, wherein the measuring probe has a base, a first intermediate portion connected to the base and located between the front end of the measuring probe and the base, and a second intermediate portion connected to the first intermediate portion and located between the first intermediate portion and the front end, wherein in the portion of the measuring probe including from the front end to the first intermediate portion, the diameter at a first measuring position is greater than or equal to the diameter at a second measuring position located between the first measuring position and the front end in the direction in which the axis extends, and when the angle between the tangent to the surface of the measuring probe in a cross-section including the axis and the axis is defined as the inclination angle, the inclination angle of the first intermediate portion is greater than the inclination angle of the base, and the inclination angle of the second intermediate portion is less than or equal to the inclination angle of the first intermediate portion.

2. The measuring tool according to claim 1, wherein the second intermediate portion has a portion in which the inclination angle is smaller than that of the base portion.

3. In the cross-section, the surface of the base is straight, and the surfaces of the first intermediate portion and the second intermediate portion are recessed in the direction toward the axis with respect to a virtual straight line that overlaps the surface of the base. The measuring tool according to claim 1 or claim 2.

4. The measuring tool according to claim 3, wherein the measuring probe has a tip portion forming the front end, the surface of the tip portion is arc-shaped in the cross-section, and the distance between the front end and the second intermediate portion in the direction in which the axis extends is greater than or equal to the value obtained by multiplying the radius of the tip portion in the cross-section by tan 30° and less than or equal to four times the radius of the tip portion in the cross-section.

5. The measuring tool according to any one of claims 1 to 4, wherein the measuring probe has a third intermediate portion that is connected to the second intermediate portion and located between the second intermediate portion and the front end, and in the cross-section, the surface of the third intermediate portion is straight, and the inclination angle of the third intermediate portion is greater than the inclination angle of the second intermediate portion.

6. The measuring tool according to any one of claims 1 to 5, further comprising a support portion joined to the measuring probe at its rear end, wherein, when viewed perpendicular to the axis, the width of the measuring probe at the joint surface between the measuring probe and the support portion is 0.1 mm or more and 10 mm or less.

7. The measuring tool according to any one of claims 1 to 6, wherein the value obtained by subtracting the inclination angle of the base from the maximum value of the inclination angle at the first intermediate portion is 0.01° or more and 5° or less.

8. The measuring tool according to claim 1 or claim 2, wherein in the cross-section, the portion of the measuring probe including the front end to the first intermediate portion is located between a virtual straight line overlapping the surface of the base and the axis.

9. The measuring tool according to any one of claims 1 to 8, wherein the measuring probe is formed of a hard material mainly composed of one of diamond, cemented carbide, ruby, sapphire, and silicon carbide.

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