Measuring jig and method for measuring radial dimensions of spline using the measuring jig

Abstract

To simplify operations to measure the radial dimension of a spline.SOLUTION: A jig for measurement is used in measuring the radial dimension of a spline formed on the outer periphery of a shaft. The jig for measurement is formed into a cylindrical shape to be externally fit onto the shaft. The jig for measurement has a pair of flat surfaces provided at phases shifted from each other by 180° when seen from the direction of an axis of the shaft. The pair of flat surfaces are orthogonal to the axis when seen from the radial direction of the axis, and provided at positions in the direction of the axis, which are aligned to each other. The pair of flat surfaces are provided in a plurality of sets, at positions shifted in a circumferential direction around the axis and at positions shifted in the direction of the axis.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a measuring jig and a method for measuring the radial dimension of a spline using the measuring jig. [Background technology]

[0002] Patent Document 1 discloses a measuring jig for measuring the phase of a spline formed on the outer periphery of a shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-028947 Summary of the Invention [Problem to be solved by the invention]

[0004] In addition to measuring the phase, the radial dimensions of the splines formed on the outer periphery of the shaft are also measured at multiple positions in the axial direction of the shaft. Here, the measurement positions of the spline in the axial direction are determined in advance, and the operator must accurately position the measuring probe of the measuring instrument at each measurement position. In this case, it is conceivable to use a plurality of measuring jigs corresponding to the respective measurement positions, but performing measurements using a plurality of measuring jigs is time-consuming. Therefore, there is a demand for simplifying the measurement of the radial dimensions of the spline. [Means for solving the problem]

[0005] In one aspect of the present invention, the measuring jig comprises: A measuring jig used when measuring the radial dimension of a spline formed on the outer periphery of a shaft, the measuring jig is formed in a cylindrical shape to be fitted onto the shaft, the measuring jig has a pair of flat surfaces that are 180° out of phase with each other when viewed from the axial direction, The pair of flat surfaces are orthogonal to the axis when viewed from a radial direction of the axis, and are provided so as to be aligned in the axial direction, The pair of flat surfaces are provided in a plurality of sets, with positions shifted in the circumferential direction around the axis and positions shifted in the axial direction. [Effects of the Invention]

[0006] According to one aspect of the present invention, the measurement of the radial dimension of a spline can be simplified. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating the state in which the measuring jig is used. [Figure 2] FIG. 2 is a perspective view of the measuring jig. [Figure 3] FIG. 3 is a plan view of the measuring jig. [Figure 4] FIG. 4 is a development view of the measuring jig. [Figure 5] FIG. 5 is a diagram illustrating a micrometer. [Figure 6] FIG. 6 is a diagram illustrating measurement points on the shaft. [Figure 7] FIG. 7 is a diagram illustrating the attachment of the measuring jig to the shaft. [Figure 8] FIG. 8 is a diagram for explaining the positioning of the measuring jig in the circumferential direction. [Figure 9] FIG. 9 is a diagram for explaining the measurement of the radial dimension of the spline. [Figure 10] FIG. 10 is a diagram for explaining the positioning of the measuring jig in the circumferential direction. [Figure 11] FIG. 11 is a diagram for explaining the measurement of the radial dimension of the spline. [Figure 12] FIG. 12 is a diagram for explaining the positioning of the measuring jig in the circumferential direction. [Figure 13]FIG. 13 is a diagram for explaining the measurement of the radial dimension of the spline. [Figure 14] FIG. 14 is a diagram illustrating a measuring jig according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0008] First, definitions of terms used in this specification will be explained. "Overlapping when viewed in a predetermined direction" means that multiple elements are lined up in a predetermined direction, and is synonymous with "overlapping in a predetermined direction." The "predetermined direction" may be, for example, an axial direction, a radial direction, or the direction of gravity. When a drawing shows multiple elements (components, parts, etc.) arranged in a specific direction, it may be assumed that the description in the specification contains a sentence explaining that they overlap when viewed in the specific direction.

[0009] "Not overlapping when viewed in a predetermined direction" and "offset when viewed in a predetermined direction" mean that multiple elements are not lined up in a predetermined direction, and are synonymous with "not overlapping in a predetermined direction" and "offset in a predetermined direction." The "predetermined direction" is, for example, the axial direction, the radial direction, the direction of gravity, etc. If a drawing shows that multiple elements (components, parts, etc.) are not aligned in a specified direction, it may be assumed that the description in the specification contains a sentence explaining that they do not overlap when viewed in the specified direction.

[0010] "When viewed from a predetermined direction, a first element (component, part, etc.) is located between a second element (component, part, etc.) and a third element (component, part, etc.)" means that when observed from a predetermined direction, it can be observed that the first element is located between the second element and the third element. The "predetermined direction" refers to an axial direction, a radial direction, the direction of gravity, etc. For example, if the second element, the first element, and the third element are arranged in that order along the axial direction, it can be said that the first element is located between the second element and the third element when viewed in the radial direction. If the drawings show that the first element is located between the second element and the third element when viewed in a specific direction, it can be considered that the description in the specification contains a sentence explaining that the first element is located between the second element and the third element when viewed in the specific direction.

[0011] Hereinafter, an embodiment of the present invention will be described. Fig. 1 is a diagram illustrating the state in which the measuring jig 1 is used. Fig. 1 shows the state in which the measuring jig 1 is extrapolated onto a shaft 2. In Fig. 1, the outer periphery of the measuring jig 1 is cross-hatched. FIG. 2 is a perspective view of the measuring jig 1. As shown in FIG. Fig. 3 is a plan view of the measuring jig 1. In Fig. 3, to easily distinguish between flat surfaces at different positions in the direction of the axis X, the tip surfaces of the extension walls are cross-hatched and the stepped surfaces are hatched. Also, the small diameter shaft portion 21 of the shaft 2 is shown by a virtual line. Fig. 4 is a development view of the measuring jig 1 as seen from the outer periphery side. Fig. 4 shows a development view of the measuring jig 1 over the entire circumference in the counterclockwise direction, starting from reference symbol A1 in Fig. 3 and passing through reference symbols A2 to A4.

[0012] 1, shaft 2, which is the object to be measured, has a large diameter shaft portion 20 and a small diameter shaft portion 21 having a smaller diameter than large diameter shaft portion 20. Small diameter shaft portion 21 is provided on the tip 2a side in the direction of axis X of shaft 2. Splines 5 are formed on the outer peripheral surface 21a of small diameter shaft portion 21. The measuring jig 1 according to this embodiment is cylindrical and is used by being fitted onto the small diameter shaft portion 21 of the shaft 2 from the direction of the axis X.

[0013] 2, the measuring jig 1 has a cylindrical base 10 and an extension 11 extending from the base 10. The extension 11 extends in a direction along the center line C from one end face 10a of the base 10 in the direction of the center line C.

[0014] The extension portion 11 is composed of four identically shaped extension walls 12 (first extension portion), 13 (third extension portion), 14 (second extension portion), and 15 (fourth extension portion). These four extension walls 12, 13, 14, and 15 are arranged in order in the circumferential direction around the center line C.

[0015] As shown in Fig. 3, extending walls 12, 13, 14, and 15 are arranged at equal intervals in the circumferential direction around center line C, with a phase shift of 90°. Extended wall 14 is provided at a position that is 180° shifted from extending wall 12. Extended wall 15 is provided at a position that is 180° shifted from extending wall 13. Note that the radial thickness of measuring jig 1 is exaggerated in Fig. 3.

[0016] The extending walls 12, 13, 14, and 15 form an arc shape along the circumferential direction around the center line C. In the circumferential direction around the center line C, one end surface 10a of the base 10 is exposed between the extending walls 12, 13, 14, and 15.

[0017] The inner diameter of the extension walls 12, 13, 14, and 15 is the same as the inner diameter D1 of the base 10. The inner diameter D1 of the base 10 is slightly larger than the outer diameter D2 of the small diameter shaft portion 21 (see the imaginary line in the figure) of the shaft 2 (D1>D2). The measuring jig 1 is rotatable relative to the shaft 2.

[0018] As shown in Figure 4, one end face 10a and the other end face 10b of the base 10 in the direction of the center line C are flat surfaces perpendicular to the center line C. The extension walls 12, 13, 14, and 15 each extend from one end face 10a of the base 10 in the direction of the center line C. The extension walls 12, 13, 14, and 15 are equally spaced apart at a distance W3 in the circumferential direction. In the following explanation, the configuration of each part of the extension wall will be explained using the extension wall 12 as an example.

[0019] 4, the tip surface 12a of the extension wall 12 in the direction of the center line C is a flat surface perpendicular to the center line C. One side surface 121 and the other side surface 122 of the extension wall 12 in the circumferential direction are surfaces parallel to the center line C.

[0020] The extension wall 12 is provided with cutouts 125 and 126 formed by cutting out a part of the tip end surface 12a side and a part of the base portion 10 side in the direction of the center line C, respectively. The notch 125 is provided across the tip surface 12a of the extending wall 12 and the other side surface 122. The notch 126 is provided across the one side surface 121 of the extending wall 12 and one end surface 10a of the base 10.

[0021] In the region of the extending wall 12 where the notch 125 is provided, a surface 12c is formed along the center line C, and a step surface 12b is formed perpendicular to the center line C. The width W1 of the tip end surface 12a in the circumferential direction and the width W2 of the step surface 12b are set to be approximately equal to the distance W3 between the extending walls 12 and 13. These widths W1, W2, and W3 are larger than the diameter 2r (see FIG. 5) of the anvil 31 and spindle 32 of the micrometer 3, which will be described later.

[0022] The distance between the other end surface 10b of the base 10 and the step surface 12b of the extension wall 12 in the direction of the center line C is set to L2. This distance L2 is shorter than the distance L1 between the other end surface 10b of the base 10 and the tip surface 12a of the extension wall 12, and is longer than the distance L3 between the other end surface 10b of the base 10 and one end surface 10a (L3 <L2<L1)。

[0023] Therefore, in the extending wall 12, the step surface 12b is located closer to the base 10 than the tip surface 12a in the direction of the center line C. In the extending wall 12, the distance (L1-L3) between the tip surface 12a and one end surface 10a of the base 10 is greater than the distance (L2-L3) between the step surface 12b and one end surface 10a of the base 10.

[0024] In this way, in the measuring jig 1, the tip surface 12a of the extension wall 12, the step surface 12b, and one end surface 10a of the base 10 are arranged with their positions shifted in the direction of the center line C, and are also arranged with their positions shifted in the circumferential direction.

[0025] As shown in FIG. 4, the notch 126 is recessed from one side surface 121 of the extension wall 12 toward the other side surface 122 by a width W4. The width W4 is smaller than the width W1 of the tip surface 12a (W4 <W1)。

[0026] 4, the extending walls 13, 14, and 15 have the same configuration as the extending wall 12. The extending walls 13, 14, and 15 have tip surfaces 13a, 14a, and 15a, respectively, that are aligned with the tip surface 12a in the direction of the center line C, and step surfaces 13b, 14b, and 15b, respectively, that are aligned with the step surface 12b in the direction of the center line C.

[0027] Further, the extending walls 13, 14, and 15 are provided with notches 136, 146, and 156, respectively, which correspond to the notch 126. These notches 126, 136, 146, and 156 are provided to prevent the anvil 31 and spindle 32 of the micrometer 3 from interfering with the extending walls 12, 13, 14, and 15.

[0028] 3, the tip surface 14a of the extension wall 14 is located at a position shifted by 180° in phase from the tip surface 12a of the extension wall 12. These tip surfaces 12a, 14a form a pair of flat surfaces.

[0029] 3, the step surface 14b of the extension wall 14 is located at a position shifted by 180° in phase from the step surface 12b of the extension wall 12. These step surfaces 12b, 14b form a pair of flat surfaces.

[0030] 3, one end face 10a of the base 10 exposed between the extending walls 14 and 15 is located at a position shifted by 180° in phase from one end face 10a of the base 10 exposed between the extending walls 12 and 13 in the circumferential direction. These one end faces 10a, 10a form a pair of flat surfaces.

[0031] 3, the tip surface 13a of the extending wall 13 and the tip surface 15a of the extending wall 15 form a pair of flat surfaces. The step surface 13b of the extending wall 13 and the step surface 15b of the extending wall 15 form a pair of flat surfaces. In addition, one end surface 10a, 10a of the base 10 exposed between the extending walls 13 and 14 and between the extending walls 15 and 12 in the circumferential direction also form a pair of flat surfaces. In other words, the measuring jig 1 according to this embodiment has six pairs of flat surfaces.

[0032] As shown in Fig. 4, six pairs of flat surfaces are configured to respectively mount anvils 31 and spindles 32, which are the measuring elements of the micrometer 3 (see the imaginary lines in Fig. 4). In the following explanation, we will exemplify the case where the anvils 31 and spindles 32 are mounted on the following three pairs of flat surfaces out of the six pairs of flat surfaces. The tip surface 12a of the extension wall 12 and the tip surface 14a of the extension wall 14 The step surface 12b of the extension wall 12 and the step surface 14b of the extension wall 14 One end face 10a adjacent to the step face 12b and one end face 10a adjacent to the step face 14b

[0033] (micrometer 3) Fig. 5 is a diagram illustrating the micrometer 3. Fig. 5 shows the micrometer 3 as viewed from above in the vertical direction, with the micrometer 3 being held by an operator. In Fig. 5, the lower side of the figure indicates the front side as viewed from the operator, and the upper side of the figure indicates the back side as viewed from the operator.

[0034] 5, the micrometer 3 has a substantially U-shaped frame 30. An anvil 31, which is a fixed measuring element, is provided at one end 301 of the frame 30. A spindle 32, which is a movable measuring element, and an operating unit 33 that moves the spindle 32 back and forth are supported at the other end 302 of the frame 30.

[0035] The anvil 31 and the spindle 32 extend toward each other along a straight line Lx from one end 301 and the other end 302 of the frame 30. The straight line Lx is a straight line that runs along the left-right direction of the operator during measurement.

[0036] The anvil 31 has a base 310 that is oriented along the direction of the straight line Lx. The base 310 has a cylindrical shape with a radius r. The base 310 is cantilevered at one end 301 of the frame 30. A tip 311 of the base 310 in the direction of the straight line Lx has a tapered shape that becomes smaller in diameter as it moves away from the base 310. A ball 312 is provided at the smallest diameter portion of the tip 311.

[0037] The spindle 32 has a base 320 that is oriented along the direction of the straight line Lx. The base 320 has a cylindrical shape with a radius r and is provided concentrically with the base 310 of the anvil 31. The base 320 is connected to the operating unit 33 via a screw mechanism and a ratchet mechanism (not shown). A tip 321 of the base 320 in the direction of the straight line Lx has a tapered shape that becomes smaller in diameter as it moves away from the base 320. A ball 322 is provided at the smallest diameter portion of the tip 321.

[0038] The operating unit 33 is provided on the opposite side of the spindle 32 across the other end 302 of the frame unit 30. The operating unit 33 is provided so as to be rotatable around the straight line Lx. When the operating unit 33 rotates around the straight line Lx, the spindle 32 moves forward and backward in the direction of the straight line Lx.

[0039] Specifically, when the operating unit 33 is rotated in the direction to tighten the screw (arrow a in FIG. 5), the spindle 32 is displaced in the direction to approach the anvil 31 (arrow c in FIG. 5). On the other hand, when the operating unit 33 is rotated in the direction to loosen the screw (arrow b in FIG. 5), the spindle 32 is displaced in the direction to move away from the anvil 31 (arrow d in FIG. 5).

[0040] Here, the balls 312, 322 have the same diameter Q. The diameter Q of the balls 312, 322 is set to a diameter at which the outer peripheries of the balls 312, 322 abut against the valleys 52, 52 of the spline 5 on the reference circle Im (see FIG. 8). The micrometer 3 of this embodiment measures the radial dimension of the spline 5 when the balls 312, 322 are engaged with the valleys 52, 52 of the spline 5. Specifically, as shown in Fig. 5, the over-ball diameter OBD, which is the distance between the outer peripheries of the balls 312, 322 on the base portions 310, 320 sides in the direction of the straight line Lx, is measured.

[0041] A method for measuring the overball diameter OBD of the spline 5 using the measuring jig 1 will be described below. Fig. 6 is a diagram illustrating measurement points of the over-ball diameter OBD of the spline 5 on the shaft 2. Fig. 6 is a schematic diagram of a cross section of the shaft 2 cut along the axis X direction. FIG. 7 is a diagram illustrating the process of attaching the measuring jig 1 to the shaft 2. As shown in FIG. Fig. 8 is a diagram for explaining the circumferential positioning of the measuring jig 1. Fig. 8 shows the arrangement of the measuring jig 1 when measuring the first measurement point P1. FIG. 9 is a schematic diagram of the AA cross section of FIG. Fig. 10 is a diagram for explaining the circumferential positioning of the measuring jig 1. Fig. 10 shows the arrangement of the measuring jig 1 when measuring the second measurement point P2. FIG. 11 is a schematic diagram of the AA cross section of FIG. Fig. 12 is a diagram for explaining the circumferential positioning of the measuring jig 1. Fig. 12 shows the arrangement of the measuring jig 1 when measuring the third measurement point P3. FIG. 13 is a schematic diagram of the AA cross section of FIG.

[0042] 8, the spline 5 according to this embodiment has an even number of teeth (12 crests 51 and 12 valleys 52). Therefore, a pair of crests 51, 51 or a pair of valleys 52, 52 are located at positions that are shifted in phase by 180° in the circumferential direction around the axis X.

[0043] 6, in this embodiment, the over ball diameter OBD of the spline 5 is measured by engaging the balls 312, 322 of the micrometer 3 with the pair of valley portions 52, 52 in the radial direction of the axis X. In this embodiment, the over ball diameter OBD of the spline 5 is measured at the following three locations. (i) First measurement point P1 on the tip 2a side of the shaft 2 in the direction of the axis X (ii) A second measurement point P2 located approximately in the middle of the spline 5 in the direction of the axis X (iii) Third measurement point P3 on the large diameter shaft portion 20 side in the axial line X direction

[0044] 6, the first measurement point P1, the second measurement point P2, and the third measurement point P3 are set in advance with reference to the step surface 22 of the shaft 2. The distances from the step surface 22 to the first measurement point P1, the second measurement point P2, and the third measurement point P3 are LP1, LP2, and LP3, respectively (LP1>LP2>LP3).

[0045] (Set of 2 shafts) 7, the measurement of the spline 5 is performed with the axis X of the shaft 2 aligned along the vertical line. The shaft 2 is set on a measurement table (not shown) with the small diameter shaft portion 21 facing upward from the large diameter shaft portion 20.

[0046] As shown in FIG. 8, the worker rotates the shaft 2 around the axis X so that a pair of valleys 52, 52 that are 180° out of phase with each other are positioned on a straight line Lx when viewed from the direction of the axis X (white arrow in FIG. 8).

[0047] (Installation process) Next, as shown in Fig. 7, the worker inserts the measuring jig 1 onto the small diameter shaft portion 21 of the shaft 2 from the base portion 10 side (in the direction of the arrow in the figure), and abuts the other end face 10b against the stepped surface 22 of the shaft 2 from the direction of the axis X (mounting process). As a result, the center line C (see Fig. 2) of the measuring jig 1 is arranged concentrically with the axis X. Furthermore, when viewed from the radial direction of the axis X, the extending portion 11 overlaps the spline 5. As a result, the tip surface 12a and stepped surface 12b of the extending wall 12 and one end face 10a of the base portion 10 are arranged in positions that overlap the area where the spline 5 is formed.

[0048] (Positioning process) 8, the worker rotates the measuring jig 1 around the axis X to position the tip surfaces 12a, 14a of the extending walls 12, 14 at a position overlapping with the straight line Lx (indicated by the black arrows in the figure). As a result, the tip surfaces 12a, 14a of the extending walls 12, 14 are positioned to overlap with the pair of valley portions 52, 52 in the direction of the straight line Lx. Note that instead of the tip surfaces 12a, 14a of the extending walls 12, 14, the tip surfaces 13a, 15a of the extending walls 13, 15 may be positioned to overlap with the straight line Lx.

[0049] (Measurement process) 8, the worker places the anvil 31 and the spindle 32 of the micrometer 3 on the tip surfaces 12a and 14a of the extension walls 12 and 14. As a result, the anvil 31 and the spindle 32 are positioned opposite the pair of valley portions 52 and 52 in the direction of the straight line Lx (see the imaginary lines in the figure).

[0050] As shown in FIG. 9, during measurement, the anvil 31 and spindle 32 of the micrometer 3 abut against the tip surfaces 12a, 14a of the extension walls 12, 14 from the direction of the axis X (upper side in the vertical direction).

[0051] Here, in the measuring jig 1, the distance from the other end surface 10b of the base 10 to the pair of flat surfaces in the direction of the axis X takes into consideration the radius r of the anvil 31 and the spindle 32 of the micrometer 3. 9, the distance L1 in the direction of the axis X from the other end surface 10b of the base 10 to the tip surfaces 12a, 14a (a pair of flat surfaces) of the extending walls 12, 14 is set to be shorter than the distance LP1 by the radius r of the anvil 31 and the spindle 32 (LP1 = L1 + r). As a result, when the anvil 31 and the spindle 32 abut against the tip surfaces 12a, 14a of the extending walls 12, 14, the centers of the balls 312, 322 are positioned at the first measurement point P1.

[0052] Next, while engaging the ball 312 of the anvil 31 with one of the valley portions 52, the operator rotates the operating part 33 in the direction of tightening the screw (arrow a in Figure 5) to engage the ball 322 of the spindle 32 with the other valley portion 52 (direction of arrow c in Figure 9). Then, the worker measures the over-ball diameter OBD when the rotation of the operating part 33 switches to idling, thereby measuring the over-ball diameter OBD of the spline 5 at the first measurement point P1.

[0053] (Positioning process) Next, the operator rotates the operating part 33 in the direction to loosen the screw (arrow b in FIG. 5), slightly separating the ball 322 of the spindle 32 from the other valley portion 52 (arrow d direction in FIG. 9). As a result, the balls 312 and 322 are loosely fitted in the valley portions 52 and 52, respectively.

[0054] 10, the worker rotates the measuring jig 1 clockwise to position the tip surfaces 12a, 14a of the extending walls 12, 14 at an angle θ1 with respect to the straight line Lx. Specifically, the worker rotates the measuring jig 1 until the step surfaces 12b, 14b of the extending walls 12, 14 overlap the straight line Lx (indicated by the black arrows in the figure). As a result, the step surfaces 12b, 14b of the extending walls 12, 14 are positioned to overlap the pair of valley portions 52, 52, respectively, in the direction of the straight line Lx.

[0055] (Measurement process) As shown in FIG. 11, the operator moves the micrometer 3 downward in the vertical direction to bring the anvil 31 and the spindle 32 into contact with the step surfaces 12b and 14b of the extension walls 12 and 14 (white arrows in the figure).

[0056] The distance L2 from the other end surface 10b of the base 10 in the direction of the axis X to the step surfaces 12b, 14b of the extending walls 12, 14 is set to be shorter than the distance LP2 by the radius r of the anvil 31 and the spindle 32 (LP2 = L2 + r). As a result, when the anvil 31 and the spindle 32 abut against the step surfaces 12b, 14b of the extending walls 12, 14, the centers of the balls 312, 322 are positioned at the second measurement point P2.

[0057] Next, while engaging the ball 312 of the anvil 31 with one of the valley portions 52, the operator rotates the operating part 33 in the direction of tightening the screw (arrow a in Figure 5) to engage the ball 322 of the spindle 32 with the other valley portion 52 (direction of arrow c in Figure 9). Then, the worker measures the over-ball diameter OBD when the rotation of the operating part 33 switches to idling, thereby measuring the over-ball diameter OBD of the spline 5 at the second measurement point P2.

[0058] (Positioning process) Next, the operator rotates the operating part 33 in the direction to loosen the screw (arrow b in FIG. 5), slightly separating the ball 322 of the spindle 32 from the other valley portion 52 (arrow d direction in FIG. 11). As a result, the balls 312 and 322 are loosely fitted in the valley portions 52 and 52, respectively.

[0059] 12, the worker rotates the measuring jig 1 clockwise to position the tip surfaces 12a, 14a of the extension walls 12, 14 at an angle θ2 with respect to the straight line Lx. Specifically, the worker rotates the measuring jig 1 until one end surface 10a, 10a of the base 10 overlaps with the straight line Lx (indicated by the black arrow in the figure). As a result, the one end surfaces 10a, 10a of the base 10 are positioned to overlap with the pair of valleys 52, 52 in the direction of the straight line Lx.

[0060] (Measurement process) As shown in FIG. 13, the operator moves the micrometer 3 downward in the vertical direction, and brings the anvil 31 and the spindle 32 into contact with one end surface 10 a of the base 10 .

[0061] The distance L3 from the other end face 10b of the base 10 to the one end face 10a of the base 10 in the direction of the axis X is set to be shorter than the distance LP3 by the radius r of the anvil 31 and the spindle 32 (LP3 = L3 + r). As a result, when the anvil 31 and the spindle 32 abut against the one end faces 10a, 10a of the base 10, the centers of the balls 312, 322 are positioned at the third measurement point P3.

[0062] Next, while engaging the ball 312 of the anvil 31 with one of the valley portions 52, the operator rotates the operating part 33 in the direction of tightening the screw (arrow a in Figure 5) to engage the ball 322 of the spindle 32 with the other valley portion 52 (direction of arrow c in Figure 13). Then, the worker measures the over-ball diameter OBD when the rotation of the operating part 33 switches to idling, thereby measuring the over-ball diameter OBD of the spline 5 at the third measurement point P3.

[0063] Here, the overball diameter OBD of the spline 5 may be measured not only for the pair of measured valleys 52, 52, but also for a pair of valleys 52', 52' (see FIG. 12) that are positioned 90° out of phase with the pair of valleys 52, 52. The pair of valleys 52', 52' are located on one side and the other side of a straight line Ly that runs along the front-rear direction when viewed from the axis X direction.

[0064] When measuring the pair of valleys 52', 52', the worker rotates the shaft 2 together with the measuring jig 1 by 90° around the axis X, and positions the pair of valleys 52', 52' on the straight line Lx. Although detailed explanation will be omitted, in the same manner as in the measurement of the pair of valleys 52, 52 described above, measurements are also performed at the first measurement point P1 to the third measurement point P3 for the pair of valleys 52', 52' arranged on the straight line Lx by alternately repeating the positioning process and the measurement process.

[0065] As described above, in this embodiment, the operator can switch between the pair of flat surfaces on which the anvil 31 and spindle 32 of the micrometer 3 are placed by simply rotating the measuring jig 1 around the axis X and sequentially displacing the pair of flat surfaces (tip surfaces 12a, 14a, step surfaces 12b, 14b, and one end surfaces 10a, 10a) in the circumferential direction. Then, the operator simply moves the micrometer 3 downward in the vertical direction in sequence. This makes it easy to perform measurements at the first measurement point P1 to the third measurement point P3.

[0066] (Comparative Example) FIG. 14 is a diagram illustrating a comparative example. In the comparative example, three measuring jigs 100A, 100B, and 100C with different heights are used to perform measurements at the first measurement point P1 to the third measurement point P3 (see FIG. 6).

[0067] As shown in FIG. 14, measuring jigs 100A, 100B, and 100C are cylindrical and surround center lines C1, C2, and C3, respectively. One end face 101 and the other end face 102 of the measuring jig 100A in the direction of the center line C1 are flat surfaces perpendicular to the center line C1. A distance L100 between the one end face 101 and the other end face 102 in the direction of the center line C1 is equal to a distance L1 (see FIG. 4) from the other end face 10b of the base 10 to the tip face 12a of the extending wall 12 according to this embodiment (L100=L1).

[0068] One end face 103 and the other end face 104 of the measuring jig 100B in the direction of the center line C2 are flat surfaces perpendicular to the center line C2. A distance L200 between the one end face 103 and the other end face 104 in the direction of the center line C2 is equal to a distance L2 (see FIG. 4) from the other end face 10b of the base 10 to the step surface 12b of the extension wall 12 according to this embodiment (L200=L2).

[0069] One end face 105 and the other end face 106 of the measuring jig 100C in the direction of the center line C3 are flat surfaces perpendicular to the center line C3. A distance L300 between the one end face 105 and the other end face 106 in the direction of the center line C3 is equal to the distance L3 (see FIG. 4) from the other end face 10b to the one end face 10a of the base 10 according to this embodiment (L300=L3).

[0070] The measurement of the over-ball diameter OBD of the spline 5 using these measuring jigs 100A to 100C is carried out in the following procedure. (a) The measuring jig 100A is fitted onto the small diameter shaft portion 21 of the shaft 2, and the other end face 102 is brought into contact with the step face 22 of the shaft 2 (see the imaginary line in FIG. 14). (b) The anvil 31 and spindle 32 of the micrometer 3 are brought into contact with one end surface 101 of the measuring jig 100A. (c) Operate the micrometer 3 to measure the over-ball diameter OBD of the spline 5. (d) Lift the micrometer 3 and move it away from the spline 5. (e) The measuring jig 100A is removed from the small diameter shaft portion 21. (f) Thereafter, the above steps (a) to (e) are repeated for each of the measuring jigs 100B and 100C.

[0071] In the comparative example, when measuring the first measurement point P1 to the third measurement point P3, the worker needs to replace the measuring jigs 100A to 100C. Furthermore, in order to replace the measuring jigs 100A to 100C, the worker needs to lift the micrometer 3 and move it away from the spline 5. In this case, the balls 312, 322 of the micrometer 3 temporarily move away from the valleys 52, 52 of the spline 5.

[0072] From the viewpoint of measurement accuracy, it is preferable that the measurements of the first measurement point P1 to the third measurement point P3 are performed at the common valley portion 52, 52. Therefore, the worker needs to keep track of the position of the valley portion 52 to be measured before and after replacing the measuring jigs 100A to 100C, which places a heavy burden on the worker. The more teeth the spline 5 has, the more difficult it becomes to keep track of the position of the valley portion 52 to be measured.

[0073] In contrast, the measuring jig 1 according to this embodiment has a pair of flat surfaces (a pair of tip surfaces 12a, 14a, a pair of step surfaces 12b, 14b, and a pair of one end surfaces 10a, 10a) corresponding to the first measurement point P1 to the third measurement point P3 in a single member, thereby reducing the effort and cost required to prepare and replace multiple measuring jigs.

[0074] Furthermore, simply by rotating the measuring jig 1 around the axis X, the pair of flat surfaces on which the anvil 31 and spindle 32 of the micrometer 3 are placed can be switched. This allows the operator to move the micrometer 3 downward in the vertical direction from the first measurement point P1 to the third measurement point P3 in order, while keeping the balls 312, 322 of the micrometer 3 loosely fitted in the valleys 52, 52. Therefore, the operator does not need to know the position of the valley 52 to be measured. The operation of lifting the micrometer 3 is also unnecessary. This reduces the workload on the operator.

[0075] In this embodiment, the measuring jig 1 is shown to have four extending walls 12 to 15, but is not limited to this. The measuring jig 1 may have only two extending walls 12 and 14, or only two extending walls 13 and 15. Alternatively, the measuring jig 1 may have an even number of extending walls, six or more.

[0076] When four extending walls 12 to 15 are provided as in this embodiment, it is possible to use the extending walls 12, 14 or the extending walls 13, 15 that are located near the valley portions 52, 52. Therefore, the amount of operation of the measuring jig 1 in the positioning step can be reduced compared to when only two extending walls 12, 14 are provided. This allows for a quick transition to the measurement step.

[0077] Examples of the measuring jig 1 according to an embodiment of the present invention are listed below. (1) The measuring jig 1 is used to measure the over ball diameter OBD (radial dimension) of a spline 5 formed on the outer periphery of a shaft 2. The measuring jig 1 has a cylindrical shape that is fitted onto the shaft 2 in the direction of the axis X of the shaft 2 . The measuring jig 1 has tip surfaces 12a and 14a, which are a pair of flat surfaces that are provided with a phase difference of 180° when viewed from the direction of the axis X. The measuring jig 1 has step surfaces 12b and 14b, which are a pair of flat surfaces that are provided with a phase difference of 180° when viewed from the direction of the axis X. The measuring jig 1 has end faces 10a, 10a which are a pair of flat surfaces that are shifted in phase by 180° when viewed from the direction of the axis X. The tip surfaces 12a and 14a are perpendicular to the axis X when viewed from the radial direction of the axis X, and are provided so as to be aligned in the direction of the axis X. The step surfaces 12b and 14b are perpendicular to the axis X when viewed from the radial direction of the axis X, and are provided so as to be aligned in the direction of the axis X. The end faces 10a, 10a are perpendicular to the axis X when viewed from the radial direction of the axis X, and are provided so as to be aligned in the axis X direction. The tip surfaces 12a, 14a, step surfaces 12b, 14b, and one end surfaces 10a, 10a, which are pairs of flat surfaces, are offset in position in the circumferential direction around the axis X and also offset in position in the direction of the axis X.

[0078] With this configuration, measurement can be performed at each measurement point of the spline 5 set at different positions in the direction of the axis X simply by rotating the measuring jig 1 around the axis X and displacing the pair of flat surfaces in the circumferential direction. This simplifies the measurement work of the spline 5. Specifically, in the measuring jig 1, the pair of flat surfaces, i.e., the tip surfaces 12a, 14a, the step surfaces 12b, 14b, and the one end surfaces 10a, 10a, correspond to the first to third measurement points P1 to P3, respectively. Therefore, simply by placing the anvil 31 and the spindle 32 of the micrometer 3 on these pair of flat surfaces, the anvil 31 and the spindle 32 of the micrometer 3 can be appropriately positioned at the first to third measurement points P1 to P3. Furthermore, simply by rotating the measuring jig 1, the pair of flat surfaces on which the anvil 31 and spindle 32 of the micrometer 3 are placed can be switched. At this time, it is only necessary to move the micrometer 3 in the direction of the axis X. Therefore, as in the comparative example shown in FIG. 14, when replacing the multiple measuring jigs 100A to 100C, it is not necessary to move the micrometer 3 away from the spline 5 each time. Therefore, by using the measuring jig 1, the operator can easily perform measurements at the first measurement point P1 to the third measurement point P3.

[0079] (2) The measuring jig 1 is a base 10 that is inserted onto the shaft 2 and positioned thereon; The spline 5 has an extension 11 that extends from the base 10 in the direction of the axis X and overlaps with the spline 5 when viewed in the radial direction of the axis X. The extension portion 11 has an extension wall 12 (first extension portion) having a tip surface 12a, which is one of a plurality of pairs of flat surfaces, and a step surface 12b, and an extension wall 14 (second extension portion) having a tip surface 14a, which is the other flat surface, and a step surface 14b, formed thereon. The extension wall 12 and the extension wall 14 are provided 180° out of phase with each other. One end face 10a, 10a, which is one of the pairs of flat faces, is formed on the base 10.

[0080] With this configuration, simply by extrapolating and positioning the base 10 onto the shaft 2, the tip surfaces 12a, 14a, the step surfaces 12b, 14b, and the one end surfaces 10a, 10a can be positioned in the axial direction corresponding to the first measurement point P1, the second measurement point P2, and the third measurement point P3 of the spline 5, respectively.

[0081] (3) In the extension wall 12, the tip surface 12a and the step surface 12b are provided at different positions in the circumferential direction around the axis X. In the extension wall 14, the tip surface 14a and the step surface 14b are provided at positions shifted in the circumferential direction around the axis X. The distance from one end face 10a of the base 10 increases from the step faces 12b, 14b located on the other side in the circumferential direction around the axis X toward the tip faces 12a, 14a located away on one side.

[0082] With this configuration, when placing the anvil 31 and spindle 32 of the micrometer 3 on the tip surfaces 12a, 14a, the step surfaces 12b, 14b, and the one end surfaces 10a, 10a in that order, the operator only needs to move the micrometer 3 in one direction, from top to bottom in the vertical direction. This eliminates the need for the operator to lift the micrometer 3, thereby reducing the workload during measurement.

[0083] (4) The extension portion 11 further has an extension wall 13 (third extension portion) on which a tip surface 13a, which is one of a plurality of pairs of flat surfaces, and a step surface 13b are formed, and an extension wall 15 (fourth extension portion) on which a tip surface 15a, which is the other flat surface, and a step surface 15b are formed. When viewed from the direction of the axis X, the extension walls 13 and 15 are provided with a phase shift of 180°, and are provided with a phase shift of 90° from the extension walls 12 and 14 . The tip surfaces 13a and 15a are provided so as to be aligned with the tip surfaces 12a and 14a in the direction of the axis X. The step surfaces 13b and 15b are provided so as to be aligned with the step surfaces 12b and 14b in the direction of the axis X.

[0084] With this configuration, of the four extending walls 12, 13, 14, and 15, it is possible to use two extending walls (extending walls 12, 14 or extending walls 13, 15) that are located near the valleys 52, 52 on the straight line Lx. Therefore, compared to a configuration that includes only the two extending walls 12 and 14, it is possible to reduce the amount of manipulation of the measuring jig 1 when rotating it around the axis X. This allows for a quick transition to the measurement process.

[0085] (5) In the extension wall 13, the tip end surface 13a and the step surface 13b are provided at different positions in the circumferential direction around the axis X. In the extension wall 15, the tip surface 15a and the step surface 15b are provided at positions shifted in the circumferential direction around the axis X. The distance from one end face 10a of the base 10 increases from the step faces 13b, 15b located on the other side in the circumferential direction around the axis X toward the tip faces 13a, 15a located away on one side.

[0086] With this configuration, when placing the anvil 31 and spindle 32 of the micrometer 3 on the tip surfaces 13a, 15a, the step surfaces 13b, 15b, and the one end surfaces 10a, 10a in that order, the operator only needs to move the micrometer 3 in one direction, from top to bottom in the vertical direction. This eliminates the need for the operator to lift the micrometer 3, thereby reducing the workload during measurement.

[0087] The present invention can also be specified as a method for measuring the radial dimension of a spline using the measuring jig 1. in particular, (6) A method for measuring the over ball diameter OBD (radial dimension) of a spline 5 using a measuring jig 1, a mounting step of extrapolating the measuring jig 1 onto the shaft 2; a positioning step of rotating the measuring jig 1 around the axis X to position the pair of flat surfaces, i.e., the tip end surfaces 12a, 14a, the step surfaces 12b, 14b, or the one end surfaces 10a, 10a, on the outer diameter side of the valley portions 52, 52 of the spline 5 to be measured; and a measuring step of placing the anvil 31 and spindle 32 (a pair of probes) of the micrometer 3 on the tip surfaces 12a, 14a, the step surfaces 12b, 14b, or the one end surfaces 10a, 10a positioned on the outer diameter side of the valley portions 52, 52 of the spline 5, and measuring the over ball diameter OBD of the spline 5.

[0088] With this configuration, the pair of flat surfaces on which the anvil 31 and spindle 32 of the micrometer 3 are placed can be switched simply by displacing the pair of flat surfaces in the circumferential direction. Therefore, measurements can be easily performed at the first measurement point P1 to the third measurement point P3 without having to prepare and replace multiple measurement jigs each time.

[0089] In this embodiment, the extending wall 12 has one step surface 12b between the tip surface 12a and the one end surface 10a in the direction of the axis X (see FIG. 4). However, this is not limited to this. The extending wall 12 may have multiple step surfaces between the tip surface 12a and the one end surface 10a in the direction of the axis X. This can be changed as appropriate depending on the number of measurement points in the direction of the axis X. The multiple step surfaces may be formed in a step-like shape that approaches from the tip surface 12a to the one end surface 10a in the direction of the axis X as it moves from one side surface 121 to the other side surface 122 in the circumferential direction. The same applies to the extending walls 13 to 15.

[0090] In addition, in this embodiment, the spline 5 has been exemplified as having an even number of teeth (12 teeth) (see FIG. 8). However, the spline 5 may have an odd number of teeth. Although not shown, in the case of an odd number of teeth, the peaks 51 and the valleys 52 are located at positions that are 180° out of phase with each other in the circumferential direction around the axis X. Therefore, when the valleys 52 are located on one side in the direction of the straight line Lx, the peaks 51 are located on the other side. In this case, the measuring jig 1 is rotated to position the pair of flat surfaces so that they overlap the valley portion 52 and the peak portion 51 in the direction of the straight line Lx. Next, the anvil 31 of the micrometer 3 is engaged with the valley portion 52, and the spindle 32 is brought into contact with the apex of the peak portion 51 to measure the over-ball diameter OBD. In this way, the measuring jig 1 according to this embodiment can be used to measure the over ball diameter OBD regardless of the number of teeth of the spline 5.

[0091] Although the embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configuration of the above embodiment. Appropriate modifications are possible within the scope of the technical concept of the invention. [Explanation of symbols]

[0092] 1: Measuring jig 2: Shaft 3: Micrometer 5: Spline 10: Base 11: Extension part 12: Extension wall (first extension part) 13: Extension wall (third extension part) 14: Extension wall (second extension part) 15: Extension wall (4th extension part) 31: Anvil (probe) 32: Spindle (measuring element) 52: Valley 10a: One end face (a pair of flat faces) 12a, 14a: Tip surface (a pair of flat surfaces) 13a, 15a: Tip surface (a pair of flat surfaces) 12b, 14b: Step surface (a pair of flat surfaces) 13b, 15b: Step surface (a pair of flat surfaces) Lx: Straight line OBD: Over Ball Diameter P1: First measurement point P2: Second measurement point P3: Third measurement point X: Axis line

Claims

1. A measuring jig used when measuring the radial dimension of a spline formed on the outer periphery of a shaft, the measuring jig is formed in a cylindrical shape to be fitted onto the shaft, the measuring jig has a pair of flat surfaces that are 180° out of phase with each other when viewed from the axial direction of the shaft, The pair of flat surfaces are orthogonal to the axis when viewed from a radial direction of the axis, and are provided so as to be aligned in the axial direction, The measuring jig includes a plurality of pairs of flat surfaces, each of which is provided with its position shifted in the circumferential direction around the axis and its position shifted in the axial direction.

2. In claim 1, The measuring jig is a base portion that is inserted onto the shaft and positioned thereon; an extension portion that extends from the base portion in the axial direction and overlaps the spline when viewed in the radial direction, the extension portion has a first extension portion on which one of the pairs of flat surfaces is formed, and a second extension portion on which the other flat surface is formed, When viewed from the axial direction, the first extending portion and the second extending portion are provided with a phase difference of 180°, One of the plurality of pairs of flat surfaces is formed on the base portion.

3. In claim 2, A measuring jig in which the first extension portion and the second extension portion have a plurality of pairs of flat surfaces that are offset in the circumferential direction, and the distance from the base increases as one moves from the flat surface located on the other side in the circumferential direction to the flat surface farther away on one side in the circumferential direction.

4. In claim 2, the extending portion further includes a third extending portion on which one of the pairs of flat surfaces is formed, and a fourth extending portion on which the other flat surface is formed, A measuring jig wherein, when viewed from the axial direction, the third extension portion and the fourth extension portion are arranged with a phase shift of 180° and are arranged with a phase shift of 90° from the first extension portion and the second extension portion.

5. In claim 4, In the third extension portion and the fourth extension portion, the pair of flat surfaces are provided in multiple positions shifted in the circumferential direction, and the distance from the base increases as you move from the flat surface located on the other side in the circumferential direction to the flat surface away from one side in the circumferential direction, a measuring jig.

6. A method for measuring a radial dimension of the spline using the measuring jig according to any one of claims 1 to 5, comprising: a mounting step of extrapolating the measuring jig onto the shaft; a positioning step of rotating the measuring jig around the axis so that the pair of flat surfaces are positioned on the outer diameter side of the spline to be measured; a measuring step of placing a pair of probes on the pair of flat surfaces arranged on the outer diameter side of the spline to measure the radial dimension of the spline.

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