Ball screw device inspection method, inspection jig, and inspection device

Abstract

To provide a method for inspection that can readily confirm the number of balls after a ball screw device is assembled.SOLUTION: In inspecting the number of balls 30 disposed in circulation paths S1-S3 of a ball screw device 1, a method for inspecting a ball screw device includes the steps of: inserting an inspection jig 40 between the balls 30 disposed in the circulation paths S1-S3 from a gap between a nut 10 and a screw shaft 20; and inspecting the number of balls 30 from an insertion state of the inspection jig 40 at the time.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an inspection method, an inspection jig, and an inspection device for a ball screw device. [Background technology]

[0002] In a ball screw device, a large number of balls are arranged in a rolling path formed by a screw groove formed on the inner peripheral surface of the nut and a screw groove formed on the outer peripheral surface of the screw shaft. The starting point and the end point of the rolling path are connected by a return passage formed in a circulation member such as a tube, and a circulation path is formed for circulating the balls through this rolling path and return passage. For example, Patent Document 1 listed below discloses a method for incorporating balls into the circulation path, in which balls are incorporated from the inner peripheral side of the nut. Furthermore, Patent Document 2 listed below discloses a method for providing an opening for ball insertion on the outer peripheral surface of the nut, and incorporating the balls into the circulation path through this opening. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2530403 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-99256 Summary of the Invention [Problem to be solved by the invention]

[0004] When balls are installed in the circulation path of a ball screw device, the number of balls installed in the circulation path may be too few or too many due to malfunctions in the assembly equipment or balls getting into screw grooves that are not used as a circulation path. However, when the ball screw device is assembled, the balls are almost invisible from the outside, making it difficult to confirm the number of balls.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an inspection method that can easily check the number of balls in the circulation path after assembling a ball screw device. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a method for inspecting the number of balls arranged in a circulating path of a ball screw device, the method comprising: The present invention provides an inspection method for a ball screw device, in which an inspection jig is inserted between the balls arranged in the circulation path from a gap between the nut and the screw shaft of the ball screw device, and the number of balls is inspected based on the degree of insertion of the inspection jig at this time.

[0007] In a ball screw device, circumferential gaps are provided between the balls to allow the balls to roll within the circulation path. Therefore, if the number of balls arranged in the circulation path is greater than the appropriate number, the total gap between the balls will be small, and if the number of balls arranged in the circulation path is less than the appropriate number, the total gap between the balls will be large. Therefore, after assembling the ball screw device, when an inspection jig is inserted between the balls arranged in the circulation path through the gap between the nut and the screw shaft, the insertion depth of the inspection jig varies depending on the number of balls arranged in the circulation path. Therefore, the insertion depth of the inspection jig inserted between the balls can be used to confirm whether the number of balls arranged in the circulation path is appropriate.

[0008] The inspection jig has, for example, a narrow portion and a wide portion provided rearward of the narrow portion in the insertion direction. The circumferential width of the narrow portion is greater than the total gap between the balls when the number of balls arranged in the circulation path is excessive and smaller than the total gap between the balls when the number of balls arranged in the circulation path is appropriate. The circumferential width of the wide portion is greater than the total gap between the balls when the number of balls arranged in the circulation path is appropriate and smaller than the total gap between the balls when the number of balls arranged in the circulation path is insufficient. When using this inspection jig, if the narrow portion is not inserted between the balls in the circulation path, it can be determined that the number of balls is excessive. Furthermore, if the narrow portion is inserted between the balls in the circulation path and the wide portion is not inserted, it can be determined that the number of balls is appropriate. Furthermore, if the wide portion is inserted between the balls in the circulation path, it can be determined that the number of balls is insufficient.

[0009] The inspection jig may have a step portion connecting the narrow portion and the wide portion. By providing such a step portion, it becomes clear how far the inspection jig can be inserted, making it easier to determine the number of balls using the inspection jig.

[0010] The inspection jig may be provided with a mark indicating the insertion depth for determining whether the number of balls is appropriate. In this case, the position of the mark when the inspection jig is inserted can be used to determine whether the number of balls is appropriate.

[0011] Alternatively, the number of balls may be inspected using a plurality of inspection jigs with different circumferential widths. In this case, the appropriateness of the number of balls in the circulation path can be confirmed by checking whether each inspection jig can be inserted between the balls.

[0012] When there are three or more circulation paths provided in different axial regions, an inspection jig can be directly inserted into the circulation paths at the axial ends, but it cannot be directly inserted between the balls in the intermediate circulation paths, making it difficult to inspect the number of balls. Therefore, it is preferable to use a first inspection jig and a second inspection jig as the inspection jigs, and insert the first inspection jig from one axial side and the second inspection jig from the other axial side between the balls in the intermediate circulation paths. The number of balls arranged in the intermediate circulation paths can be inspected by the insertion depth of each inspection jig.

[0013] When inserting the inspection jig between the balls, it is necessary to move the balls in the circulation path. At this time, by inserting the inspection jig between the balls while reciprocating the screw shaft and the nut relative to each other in the rotational direction, the balls can easily roll in the circulation path, making it easier to insert the inspection jig between the balls. Furthermore, the inspection jig may be inserted between the balls while being held in a state in which it can move relatively to the screw shaft and nut of the ball screw device in the rotational direction of the ball screw device.

[0014] In the above inspection method, the inspection jig is inserted between the balls in the circulation path, and when a predetermined load is applied to the inspection jig, the inspection jig can be stopped. Whether the number of balls in the circulation path is appropriate or not can be determined based on the stopping position of the inspection jig.

[0015] The above inspection method can be performed automatically by an inspection device for a ball screw device that has an inspection jig, a drive unit that inserts the inspection jig between the balls arranged in the circulation path, and a judgment unit that determines whether the number of balls in the circulation path is appropriate based on the degree of insertion of the inspection jig. [Effects of the Invention]

[0016] As described above, according to the present invention, the number of balls in the circulation path can be easily confirmed after assembling the ball screw device. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a perspective view of a ball screw device and an inspection jig. [Figure 2] FIG. 2 is a cross-sectional view of the ball screw device. [Figure 3] FIG. 10 is a schematic diagram showing the insertion state of the inspection jig when the number of balls is too small. [Figure 4] FIG. 10 is a schematic diagram showing the insertion state of the inspection jig when the number of balls is appropriate. [Figure 5] FIG. 10 is a schematic diagram showing how the inspection jig is inserted when there are an excessive number of balls. [Figure 6] FIG. 10 is a schematic diagram showing how the number of balls in three rows of circulation paths is inspected. [Figure 7] FIG. 10 is a flow chart showing the procedure for inspecting the number of balls in the three rows of circulation paths. [Figure 8] FIG. 2 is a block diagram of an inspection device. [Figure 9] FIG. 10 is a schematic diagram showing how the number of balls in four rows of circulation paths is inspected. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] In an inspection method according to one embodiment of the present invention, an inspection jig 40 is inserted between a nut 10 and a screw shaft 20 of a ball screw device 1, as shown in Fig. 1. In this specification, the circumferential direction centered on the rotation axis of the ball screw device 1 is referred to as the "circumferential direction," and the direction of the rotation axis of the ball screw device 1 is referred to as the "axial direction."

[0020] [Ball screw device configuration] As shown in FIG. 2, the ball screw device 1 includes a nut 10, a screw shaft 20, and a plurality of balls 30. A spiral screw groove 11 is formed on the inner peripheral surface of the nut 10. A spiral screw groove 21 is formed on the outer peripheral surface of the screw shaft 20. A plurality of balls 30 are arranged in a rolling path formed by the screw groove 11 of the nut 10 and the screw groove 21 of the screw shaft 20. The end point and the start point of each rolling path are connected by a return passage (not shown), thereby forming a circulation path for circulating the balls 30. The return passage is formed by a known circulation member, for example, a U-shaped tube or a circulation top embedded in the nut 10.

[0021] In this embodiment, circulation paths (three rows of circulation paths S1, S2, S3 in the illustrated example) are provided at multiple locations spaced apart in the axial direction. In the illustrated example, each circulation path S1, S2, S3 is formed by one rotation (360°) of screw grooves 11, 21 and a return passage (not shown), and the same number of balls 30 are arranged in each circulation path S1, S2, S3. Screw grooves 11, 21 in which balls 30 are not arranged are provided axially between the circulation paths S1, S2, S3.

[0022] [Inspection jig configuration] The inspection jig 40 is plate-shaped as shown in Fig. 1. The thickness of the inspection jig 40 is smaller than the radial gap between the inner peripheral surface of the nut 10 (the smallest diameter portion of the thread groove 11) and the outer peripheral surface of the screw shaft 20 (the largest diameter portion of the thread groove 21). The inspection jig 40 has sufficient rigidity to prevent deformation when inserted between the balls 30 (details will be described later), and has a thickness that is, for example, at least half the radial gap between the inner peripheral surface of the nut 10 and the outer peripheral surface of the screw shaft 20. The inspection jig 40 is made of a material that is softer than the nut 10, the screw shaft 20, and the balls 30, such as resin.

[0023] The inspection jig 40 has a narrow portion 41 provided on the leading side in the insertion direction (hereinafter referred to as the "tip side"), and a wide portion 42 provided on the rear side in the insertion direction of the narrow portion 41 (hereinafter referred to as the "base side"), which has a wider circumferential width than the narrow portion. In the illustrated example, the narrow portion 41 and the wide portion 42 each consist of an axial region with a constant circumferential width. A step portion 43 is provided between the narrow portion 41 and the wide portion 42, connecting them. The step portion 43 is tapered such that its circumferential width increases toward the base end side (the wide portion 42 side). A tip portion 44 of the inspection jig 40 is tapered such that its circumferential width decreases toward the tip side.

[0024] The circumferential width of the narrow portion 41 of the inspection jig 40 is larger than the total gap between the balls 30 when there are an excessive number of balls 30 arranged in each of the circulation paths S1 to S3 (for example, when there is one more than the appropriate number). In other words, when there are an excessive number of balls 30 arranged in each of the circulation paths S1 to S3, the total gap between the balls 30 is smaller than the circumferential width of the narrow portion 41 of the inspection jig 40, and therefore the narrow portion 41 of the inspection jig 40 cannot be inserted between the balls 30. In this case, as shown in FIG. 3, when the inspection jig 40 is inserted between the balls 30 of the circulation path S (a circulation path having the same configuration as the circulation paths S1 to S3) from one axial side (the left side in the figure), the inspection jig 40 stops with the tip portion 44 inserted between the balls 30 up to the middle.

[0025] Furthermore, the circumferential width of the narrow width portion 41 of the inspection jig 40 is smaller than the total gap between the balls 30 when the number of balls 30 arranged on each of the circulation paths S1 to S3 is appropriate. In other words, when the number of balls 30 arranged on each of the circulation paths S1 to S3 is appropriate, the total gap between the balls 30 is larger than the circumferential width of the narrow width portion 41 of the inspection jig 40, and therefore the narrow width portion 41 of the inspection jig 40 is inserted between the balls 30 on the circulation path S, as shown in FIG.

[0026] The circumferential width of the wide portion 42 of the inspection jig 40 is larger than the total gap between the balls 30 when the number of balls 30 arranged on each of the circulation paths S1 to S3 is appropriate. In other words, when the number of balls 30 arranged on each of the circulation paths S1 to S3 is appropriate, the total gap between the balls 30 is smaller than the circumferential width of the wide portion 42 of the inspection jig 40, and therefore the wide portion 42 of the inspection jig 40 cannot be inserted between the balls 30. In this case, as shown in FIG. 4 , when the inspection jig 40 is inserted between the balls 30 on the circulation path S from one axial side (the left side in the figure), the inspection jig 40 stops with the step 43 between the narrow portion 41 and the wide portion 42 abutting against the ball 30.

[0027] Furthermore, the circumferential width of the wide portion 42 of the inspection jig 40 is smaller than the total gap between the balls 30 when the number of balls 30 arranged on each of the circulation paths S1 to S3 is too small (for example, when the number is one less than the appropriate number). In other words, when the number of balls 30 arranged on each of the circulation paths S1 to S3 is too small, the total gap between the balls 30 is larger than the circumferential width of the wide portion 42 of the inspection jig 40, and therefore the wide portion 42 of the inspection jig 40 is inserted between the balls 30 on the circulation path S as shown in FIG. 5.

[0028] As described above, by inserting the inspection jig 40 between the balls 30 in the circulation path S and checking its stopping position, it is possible to determine whether the number of balls 30 in the circulation path S is appropriate. Specifically, if the inspection jig 40 stops before the narrow portion 41 is inserted between the balls 30, i.e., if the tip portion 44 is inserted between the balls 30 (see FIG. 3), it can be determined that there are too many balls 30 in the circulation path S. If the inspection jig 40 stops with the narrow portion 41 inserted between the balls 30 (see FIG. 4), it can be determined that the number of balls 30 in the circulation path S is appropriate. If the inspection jig 40 stops with the wide portion 42 inserted between the balls 30 (see FIG. 5), it can be determined that there are too few balls 30 in the circulation path S.

[0029] [Inspection method procedure] In this embodiment, two inspection jigs 40 are used to inspect the number of balls 30 in the three rows of circulation paths S1 to S3. This inspection method will be explained using Figures 6 and 7. Note that although the two inspection jigs 40 have the same configuration, in order to distinguish between the two inspection jigs 40, they are denoted by the symbols "40(A)" and "40(B)." Furthermore, movement of each inspection jig 40(A), 40(B) toward the side where it is inserted into the gap between the nut 10 and the screw shaft 20 is referred to as "advancement," and movement in the opposite direction is referred to as "retraction."

[0030] First, one of the inspection jigs 40(A) is advanced and inserted into the gap between the nut 10 and the screw shaft 20 from one axial side. When a load equal to or greater than a predetermined value is applied to the inspection jig 40(A), the inspection jig 40(A) is stopped (step 101). Then, it is checked whether the narrow portion 41 of the inspection jig 40(A) is inserted between the balls 30 in the circulation path S1 (step 102). If not, it is determined that there are too many balls 30 in the circulation path S1 (step 103, see FIG. 3), and the inspection ends. Next, it is checked whether the narrow portion 41 of the inspection jig 40(A) is inserted between the balls 30 in the circulation path S2 (step 104). If not, it is determined that there are too many balls 30 in the circulation path S2 (step 105, see FIG. 3), and the inspection ends. Next, it is confirmed whether the wide portion 42 of the inspection jig 40 is inserted between the balls 30 in the circulation path S1 (step 106), and if it is inserted, it is determined that the number of balls 30 in the circulation path S1 is too small (step 107, see Figure 5), and the inspection is completed.

[0031] On the other hand, as shown in Figure 6, if the narrow portion 41 is inserted between the balls 30 on the circulation paths S1 and S2 and the wide portion 42 is not inserted between the balls 30 on the circulation path S1, proceed to the next step.

[0032] In the next step 108, while the narrow portion 41 of the inspection jig 40(A) remains inserted between the balls 30 of the circulation paths S1 and S2, the inspection jig 40(B) is advanced and inserted into the gap between the nut 10 and the screw shaft 20 from the other axial side. Then, when a load equal to or greater than a predetermined value is applied to the inspection jig 40(B), the inspection jig 40(B) is stopped. Thereafter, it is confirmed whether the narrow portion 41 of the inspection jig 40(B) is inserted between the balls 30 of the circulation path S3 (step 109). If not, it is determined that there are an excessive number of balls 30 in the circulation path S3 (step 110, see FIG. 3), and the inspection ends.

[0033] At this time, since the narrow portions 41 of the inspection jig 40(A) have already been inserted between the balls 30 in the circulation path S2 (see FIG. 6), if the number of balls 30 in the circulation path S2 is appropriate, it is not possible to further insert the narrow portions 41 of the inspection jig 40(B). Therefore, it is confirmed whether or not the narrow portions 41 of the inspection jig 40(B) have been inserted between the balls 30 in the circulation path S2 (step 111), and if they have been inserted, it is determined that the number of balls 30 in the circulation path S2 is too small (step 112), and the inspection ends.

[0034] On the other hand, as shown in Figure 6, if the narrow portion 41 of the inspection jig 40(B) is inserted between the balls 30 on the circulation path S3 and is not inserted between the balls 30 on the circulation path S2, proceed to the next step.

[0035] Next, one of the inspection jigs 40(A) is retracted and pulled out from between the balls 30 in the circulation path S2 (step 113). Thereafter, the other inspection jig 40(B) is further advanced, and when a load equal to or greater than a predetermined value is applied, the inspection jig 40(B) is stopped (step 114). Thereafter, it is confirmed whether the wide portion 42 of the inspection jig 40(B) is inserted between the balls 30 in the circulation path S3 (step 115). If inserted, it is determined that the number of balls 30 in the circulation path S3 is too small (step 116), and the inspection ends.

[0036] On the other hand, if the wide portion 42 of the inspection jig 40(B) is not inserted between the balls 30 in the circulation path S3, it is determined that the number of balls 30 in all circulation paths S1 to S3 is appropriate, neither too many nor too few, taking into account the results up to that point (step 117), and the inspection ends.

[0037] [Inspection equipment configuration] The above inspection is performed automatically using, for example, an inspection device shown in FIG. 8. This inspection device includes a nut rotation unit 51 that rotates the nut 10 of the ball screw device 1, a screw shaft fixing unit (not shown) that fixes the screw shaft 20, an inspection jig holding unit (not shown) that holds the inspection jig 40 in a state where it can be moved axially and circumferentially, an inspection jig driving unit 52 that moves the inspection jig 40 in the axial direction, a control unit 53 that controls the nut rotation unit 51 and the inspection jig driving unit 52, a sensor 54 that confirms the position of the inspection jig 40, a determination unit 55 that determines whether the number of balls 30 is appropriate, and a display unit 56 such as a monitor that displays the inspection results. Note that a screw shaft rotation unit that rotates the screw shaft 20 may be provided instead of the nut rotation unit 51, and a nut fixing unit may be provided instead of the screw shaft fixing unit.

[0038] The inspection jig driving unit 52 biases the inspection jig 40 using a biasing means that uses the elastic force of a spring or the like, air pressure, or hydraulic pressure. This prevents a load greater than the biasing force of the biasing means from being applied to the inspection jig 40. In other words, when the inspection jig 40 is inserted between the balls in the circulation path, if a load greater than the biasing force of the biasing means is applied, the inspection jig 40 is stopped. Alternatively, the inspection jig driving unit 52 may be provided with a load meter or torque meter, or a servo motor capable of detecting torque may be used as the inspection jig driving unit 52. In this case, the inspection jig driving unit 52 may be controlled to stop the inspection jig 40 when it is detected that a load greater than a predetermined value has been applied to the inspection jig 40.

[0039] The ball screw device 1 and the inspection jig 40 are set in the inspection device, and the inspection jig 40 is placed on the axial extension of the radial gap between the nut 10 and the screw shaft 20 of the ball screw device 1 (see FIG. 1 ). From this state, the inspection jig 40 is moved axially by the inspection jig drive unit 52 and inserted into the gap between the nut 10 and the screw shaft 20, and then between the balls 30 arranged in the circulation paths S1 to S3. At this time, since the inspection jig 40 is held in a state where it can move freely in the circumferential direction, the circumferential position of the inspection jig 40 is automatically adjusted by the tip end 44 of the inspection jig 40 coming into contact with the balls 30, making it easy for the tip end 44 of the inspection jig 40 to be inserted between the balls 30. Furthermore, when inserting the inspection jig 40 between the balls 30, the nut rotation unit 51 reciprocates the nut 10 in the rotational direction, making it easy for the balls 30 to move within the circulation path S1, making it easy to insert the inspection jig 40 between the balls 30 while moving the balls 30 closer together. At this time, the inspection jig 40 may be inserted between the balls 30 while being held in a state in which it is movable relative to the screw shaft 20 and the nut 10 in the rotational direction of the ball screw device 1 (circumferential direction centered on the axis of the screw shaft 20 and the nut 10).

[0040] Then, when the inspection jig 40 stops, the stopping position of the inspection jig 40 at this time is detected by the sensor 54. Based on the stopping position of the inspection jig 40 detected by the sensor 54 (i.e., the degree of insertion), the judgment unit 55 judges whether the number of balls 30 on the circulation paths S1 to S3 is appropriate or not, and this judgment result is displayed on the display unit 56.

[0041] The present invention is not limited to the above-described embodiment. Other embodiments of the present invention will be described below, but explanations of the same points as those in the above-described embodiment will be omitted.

[0042] 9 shows an example of inspecting the number of balls 30 on four rows of circulation paths S1 to S4. In this case, by confirming that the narrow portions 41 of one inspection jig 40(A) are inserted between the balls 30 on the middle circulation path S2, while the narrow portions 41 of the other inspection jig 40(B) are not inserted, it can be confirmed that the number of balls 30 on the circulation path S2 is appropriate. Similarly, by confirming that the narrow portions 41 of the other inspection jig 40(B) are inserted between the balls 30 on the other middle circulation path S3, while the narrow portions 41 of the one inspection jig 40(A) are not inserted, it can be confirmed that the number of balls 30 on the other middle circulation path S3 is appropriate.

[0043] Therefore, even if the ball screw device 1 has four or more rows of circulation paths, the appropriate number of balls in the intermediate circulation path can be determined by inserting an inspection jig 40 between the balls 30 in the intermediate circulation path from one axial side and the other axial side, and checking the insertion state of each inspection jig 40 at this time.

[0044] In the above embodiment, the number of balls in the circulation path is automatically inspected by an inspection device, but this is not limited to this. An operator may manually insert an inspection jig 40 between the nut 10 and the screw shaft 20 and determine whether the number of balls is appropriate based on the degree of insertion (for example, the insertion depth of the inspection jig 40).

[0045] Furthermore, if a mark for checking the insertion depth is provided on the inspection jig 40, it becomes easier to check the stopping position of the inspection jig 40. For example, when the inspection is performed automatically, the stopping position of the inspection jig 40 can be confirmed by detecting the position of the mark provided on the inspection jig 40 with the sensor 54. Furthermore, when the inspection is performed manually, the stopping position of the inspection jig 40 can be confirmed by the operator visually checking the position of the mark provided on the inspection jig 40.

[0046] For example, a mark 45 as shown in FIG. 1 can be provided on the inspection jig 40. The mark 45 is provided at a position that radially overlaps the axial end of the nut 10 when the inspection jig 40 is properly inserted (for example, the state shown in FIG. 4). That is, if the axial end of the nut 10 and the mark 45 overlap when the inspection jig 40 is viewed from the outer periphery, it can be determined that the inspection jig 40 is properly inserted and the number of balls 30 in the circulation path S is appropriate. On the other hand, if the mark 45 is axially separated from the nut 10 when the inspection jig 40 is viewed from the outer periphery, or if the mark 45 is hidden by the inner periphery of the nut 10 and cannot be seen, it can be determined that the inspection jig 40 is not properly inserted and the number of balls in the circulation path S is not appropriate.

[0047] In the above embodiment, a case has been shown in which an inspection jig 40 having a narrow portion 41 and a wide portion 42 is used, but this is not limiting, and the number of balls may be inspected using a plurality of inspection jigs with different circumferential widths. For example, by preparing an inspection jig having the same width as the narrow portion 41 and an inspection jig having the same width as the wide portion 42, and inserting these inspection jigs in order between the balls on the circulation path, the number of balls can be inspected. [Explanation of symbols]

[0048] 1. Ball screw device 10 nuts 11 Thread groove 20 Screw shaft 21 Thread groove 30 balls 40 Inspection jig 41 Narrow part 42 Wide section 43 Step 44 Tip 51 Nut rotation part 52 Inspection jig drive unit 53 Control Unit 54 Sensors 55 Judgment section 56 Display section S, S1~S4 circulation route

Claims

1. 1. A method for inspecting the number of balls disposed in a circulating path of a ball screw device, comprising: A method for inspecting a ball screw device, in which an inspection jig is inserted between the balls arranged in the circulation path through a gap between the nut and the screw shaft of the ball screw device, and the number of balls is inspected based on the degree of insertion of the inspection jig at this time.

2. the inspection jig has a narrow portion and a wide portion provided on the rear side of the narrow portion in the insertion direction, the circumferential width of the narrow portion is larger than the total gap amount between the balls when the number of the balls arranged in the circulation path is excessive, and smaller than the total gap amount between the balls when the number of the balls arranged in the circulation path is appropriate, 2. A method for inspecting a ball screw device as described in claim 1, wherein the circumferential width of the wide portion is larger than the total gap between the balls when the number of the balls arranged in the circulation path is appropriate, and smaller than the total gap between the balls when the number of the balls arranged in the circulation path is too small.

3. The method for inspecting a ball screw device according to claim 2, wherein the inspection jig has a step portion connecting the narrow portion and the wide portion.

4. The method for inspecting a ball screw device according to any one of claims 1 to 3, wherein the inspection jig is provided with a mark for checking the insertion depth.

5. 2. The method for inspecting a ball screw device according to claim 1, wherein the number of balls is inspected using a plurality of inspection jigs having different circumferential widths.

6. the ball screw device has three or more circulation paths provided in different axial regions, As the inspection jigs, a first inspection jig and a second inspection jig are used, A method for inspecting a ball screw device according to any one of claims 1 to 5, wherein the first inspection jig is inserted between the balls in the intermediate circulation path from one axial side and the second inspection jig is inserted from the other axial side, and the number of balls arranged in the intermediate circulation path is inspected based on the insertion state of each inspection jig at this time.

7. The method for inspecting a ball screw device according to any one of claims 1 to 6, wherein the inspection jig is inserted between the balls while the screw shaft and the nut of the ball screw device are reciprocated relative to each other in a rotational direction.

8. The method for inspecting a ball screw device according to any one of claims 1 to 7, wherein the inspection jig is inserted between the balls while being held in a state where it can move relatively in the rotational direction of the ball screw device with respect to the screw shaft and nut of the ball screw device.

9. 9. The method for inspecting a ball screw device according to claim 1, wherein the inspection jig is inserted between the balls in the circulation path, and when a predetermined load is applied to the inspection jig, the inspection jig is stopped.

10. An inspection jig that is inserted between balls arranged in a circulation path of a ball screw device and inspects the number of the balls, a narrow portion and a wide portion provided on the rear side of the narrow portion in the insertion direction, the circumferential width of the narrow portion is larger than the total gap amount between the balls when the number of the balls arranged in the circulation path is excessive, and smaller than the total gap amount between the balls when the number of the balls arranged in the circulation path is appropriate, An inspection jig for a ball screw device, in which the circumferential width of the wide portion is greater than the total gap between the balls when the number of balls arranged in the circulation path is appropriate, and smaller than the total gap between the balls when the number of balls arranged in the circulation path is too small.

11. An inspection device for inspecting the number of balls arranged in a circulation path of a ball screw device, An inspection device for a ball screw device comprising: an inspection jig; an inspection jig drive unit that inserts the inspection jig between the balls arranged in the circulation path; and a judgment unit that judges whether the number of balls in the circulation path is appropriate based on the degree of insertion of the inspection jig.

Images