Ball screw and method for manufacturing ball screw

Abstract

To provide a ball screw capable of suppressing increase in size while suppressing increase in manufacturing cost, and a method for manufacturing the ball screw.SOLUTION: A method for manufacturing a ball screw including a screw shaft, a nut, a plurality of rolling elements, a piece, and a cylindrical member that is crimped to the nut by a crimping part, comprises a nut forming step S02, a first state forming step S04, a presser member arranging step S06, a cylindrical member arranging step S08, and a crimping step S10. In the nut forming step S02, the nut is formed so that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member in a region of the nut that is axially closer to the cylindrical member than the crimping part of the cylindrical member. In the presser member arranging step S06, a presser member is arranged so that its end surface is located at a predetermined axial position on the ball screw. The cylindrical member is then extrapolated onto an outer peripheral part of the nut, and crimped.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a ball screw and a method for manufacturing a ball screw. [Background technology]

[0002] A ball screw is known that includes a nut, a screw shaft that passes through the nut, and a number of rolling elements that are arranged between the nut and the screw shaft. For example, Patent Document 1 discloses a ball screw configuration that includes, in addition to the nut, the screw shaft, and the rolling elements, a number of blocks that are provided on the nut and return the rolling elements from one end to the other end of the rolling path, and a cylindrical member that holds the blocks from the outside in the radial direction. The cylindrical member is fixed to the nut by crimping, and a flange portion is provided on one end of the cylindrical member. In addition, a corner between the flange portion and the main body of the cylindrical member is formed so as to be inclined radially outward as it approaches the flange portion. According to the technology described in Patent Document 1, it is said that by forming the corner of the flange portion in a tapered shape, it is possible to improve the insertability of the cylindrical member into the nut and to suppress the falling off of metal pieces due to interference with the nut. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-182715 Summary of the Invention [Problem to be solved by the invention]

[0004] In a ball screw in which a cylindrical member for holding a top is fixed to a nut by crimping, a convex portion such as a flange or a protrusion may be provided on the outer periphery of the nut to crimp the cylindrical member. For example, in the conventional technology described in the above-mentioned Patent Document 1, one end of the cylindrical member is abutted against a flange integrally formed with the nut, and the other end of the cylindrical member is crimped to the outer periphery of the nut, thereby attaching the cylindrical member. When the cylindrical member is crimped, a butting load is generated along the axial direction of the cylindrical member. In the conventional technology described in Patent Document 1, crimping is performed by receiving the butting load during crimping by a flange provided on the outer periphery of the nut. However, in the conventional technology using a nut having a protrusion such as a flange, the manufacturing cost of the nut may increase compared to the case of using a nut whose outer circumferential surface is formed into a simple cylindrical surface. Furthermore, since it is necessary to secure an extra axial length of the nut by providing the flange, there is a risk that the nut may become large in the axial direction.

[0005] Therefore, in the prior art, in a ball screw in which a cylindrical member is arranged on the outer periphery of the nut, there was room for improvement in terms of preventing an increase in manufacturing costs while preventing the axial increase in size of the nut and the ball screw having this nut.

[0006] Therefore, an object of the present invention is to provide a ball screw that can suppress an increase in size while suppressing an increase in manufacturing costs, and a manufacturing method for this ball screw. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. A ball screw according to a first aspect of the present invention comprises a screw shaft having a spiral outer circumferential rolling groove on its outer circumferential surface, a nut having a spiral inner circumferential rolling groove on its inner circumferential surface, a plurality of rolling elements arranged in a rolling path formed by the inner circumferential rolling groove of the nut and the outer circumferential rolling groove of the screw shaft, a top attached to the nut and having a circulation path that returns the rolling elements from one end of the rolling path to the other end, and a cylindrical member having one end that is crimped to the outer circumferential surface of the nut and thereby engages with the nut to cover the top from the radial outside, and in a region opposite to the one end in the axial direction of the screw shaft than the other end of the cylindrical member, the outer diameter dimension of the nut is equal to or smaller than the inner diameter dimension of the cylindrical member.

[0008] A manufacturing method of a ball screw according to a first aspect of the present invention is a manufacturing method of a ball screw including a threaded shaft having a spiral outer circumferential rolling groove on its outer circumferential surface, a nut having a spiral inner circumferential rolling groove on its inner circumferential surface, a plurality of rolling elements arranged in a rolling path formed by the inner circumferential rolling groove of the nut and the outer circumferential rolling groove of the threaded shaft, a top attached to the nut and having a circulation path for returning the rolling elements from one end to the other end of the rolling path, and a cylindrical member having a crimped portion attached to the outer circumferential portion of the nut and covering the top from the outside in the radial direction, wherein the nut is formed such that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member in a region of the nut that is closer to the cylindrical member in the axial direction than the crimped portion of the cylindrical member. The method includes a forming step, a first state forming step of forming a ball screw in a first state in which the formed nut, the screw shaft, the rolling elements and the tops are assembled, a presser member positioning step of positioning a presser member so that an end face is positioned at a predetermined axial position on the ball screw in the first state, a cylindrical member positioning step of extrapolating the cylindrical member to the outer periphery of the nut in the ball screw in the first state and moving the cylindrical member so that one end of the cylindrical member in the axial direction is positioned at the predetermined position, and a crimping step of crimping the other end of the cylindrical member to the outer periphery of the nut by applying a load having at least the axial component to the other end of the cylindrical member in the axial direction of the cylindrical member positioned on the outer periphery of the nut. Effect of the Invention

[0009] According to the ball screw and the method for manufacturing the ball screw of the present invention, it is possible to provide a ball screw and a method for manufacturing this ball screw that can suppress an increase in size while suppressing an increase in manufacturing costs. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a ball screw according to a first embodiment. [Diagram 2] FIG. 1 is an external perspective view of a ball screw according to a first embodiment. [Diagram 3] FIG. 2 is a cross-sectional view of the nut according to the first embodiment. [Figure 4] Enlarged view of part IV in Figure 1. [Diagram 5] Enlarged view of part V in Figure 1. [Figure 6] FIG. 2 is a flow diagram of a method for manufacturing a ball screw according to the first embodiment. [Figure 7] 3A to 3C are explanatory views of a manufacturing method of a ball screw according to the first embodiment. [Figure 8] FIG. 4 is an explanatory diagram showing a state where a crimping step is completed in the manufacturing method of the ball screw according to the first embodiment. [Figure 9] 8A to 8C are explanatory views of a manufacturing method of a ball screw according to a second embodiment. [Figure 10] 13A to 13C are explanatory views of a manufacturing method of a ball screw according to a third embodiment. [Figure 11] 13A to 13C are explanatory views of a manufacturing method of a ball screw according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the center axis C of the ball screw 1, unless otherwise specified.

[0012] (First embodiment) Fig. 1 is a cross-sectional view of a ball screw 1 according to the first embodiment. Fig. 2 is a perspective view of the appearance of the ball screw 1 according to the first embodiment. The ball screw 1 is a device that converts rotational motion into linear motion. As shown in Fig. 1 and Fig. 2, the ball screw 1 of this embodiment includes a screw shaft 2, a nut 3, a plurality of rolling elements 4, a plurality of pieces 5, a cylindrical member 6, and a fitting member 7.

[0013] In the ball screw 1 of this embodiment, for example, the nut 3 rotates about the central axis C. The nut 3 is rotatable about the central axis C, but does not move in a direction along the central axis C. The screw shaft 2 connected to a driven member (not shown) does not rotate about the central axis C, but is movable in a direction along the central axis C. When the nut 3 rotates, the screw shaft 2 moves in a direction along the central axis C. The ball screw 1 is used, for example, as an electric brake device for moving a brake pad (not shown), which is an example of a driven member, of a vehicle.

[0014] (Screw shaft) The screw shaft 2 has a screw shaft body 21 and a connecting shaft 22. The screw shaft body 21 is formed in a cylindrical shape centered on a central axis C. The screw shaft body 21 is disposed inside a nut 3 described later. A spiral outer circumferential rolling groove 25 is formed on the outer periphery of the screw shaft body 21. The cross-sectional shape of the outer circumferential rolling groove 25 is a Gothic arch including two circular arcs. The outer circumferential rolling groove 25 is formed over almost the entire screw shaft body 21 in the axial direction.

[0015] The connecting shaft 22 is connected to an end face of the threaded shaft body 21 on a first axial side (the right side in FIG. 1). The connecting shaft 22 is formed integrally with the threaded shaft body 21. The connecting shaft 22 is formed in a cylindrical shape that is coaxial with the threaded shaft body 21 and has an outer diameter smaller than that of the threaded shaft body 21. A spline groove 27 is formed on the outer periphery of the connecting shaft 22. The connecting shaft 22 is connected to a driven member (not shown) by this spline groove 27. The shape of the connecting shaft 22 is not limited to a cylindrical shape. The connecting shaft 22 may be connected to the driven member by a method other than a spline, such as a gear.

[0016] (nut) FIG. 3 is a cross-sectional view of the nut 3 according to the first embodiment. In FIG. 3, a part of the inner circumferential rolling groove 31 is omitted, but in reality, the inner circumferential rolling groove 31 is formed over the entire axial direction of the nut. As shown in FIGS. 1 to 3, the nut 3 is formed in a cylindrical shape centered on the central axis C. The screw shaft body 21 is inserted into the nut 3. The inner circumferential rolling groove 31, the receiving hole 33, and the crimping recess 35 are formed in the nut 3. As shown in FIG. 3, the inner circumferential rolling groove 31 is a spiral groove provided on the inner peripheral surface of the nut 3. The cross-sectional shape of the inner circumferential rolling groove 31 is a gothic arch including two arcs. The inner circumferential rolling groove 31 is formed over almost the entire axial direction of the nut 3.

[0017] The accommodating hole 33 penetrates the nut 3 in the radial direction. The accommodating hole 33 is formed as an elongated hole along the approximate circumferential direction. A plurality of the accommodating holes 33 (four in this embodiment) are provided and arranged at equal intervals in the axial and circumferential directions. Each of the accommodating holes 33 accommodates a piece 5, which will be described in detail later. Each of the accommodating holes 33 is provided with a step portion 36 (see also FIG. 5) formed so that the diameter of the radially inner portion is smaller than that of the radially outer portion.

[0018] Fig. 4 is an enlarged view of a portion IV in Fig. 1. Fig. 5 is an enlarged view of a portion V in Fig. 1. As shown in Figs. 1 and 4, the crimping recess 35 is formed on the outer periphery of the nut 3. As shown in Fig. 1, the crimping recess 35 is provided on the second axial side (the left side in Fig. 1) of all the receiving holes 33 in the axial direction. The crimping recess 35 is a groove that continues in the circumferential direction. Note that the crimping recess 35 may be a plurality of depressions or the like that are formed discontinuously in the circumferential direction. In this embodiment, the outer peripheral surface of the nut 3 is a cylindrical surface having the same outer diameter dimension D1 over the entire surface, except for the above-mentioned crimping recess 35 and the accommodating hole 33. Over the entire region of the nut 3 in the axial direction, the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 (D1≦D2). In other words, the outer peripheral portion of the nut 3 is formed without having any portion (for example, a flange, a convex portion, a projection, etc.) that protrudes radially outward from the outer peripheral portion main surface 30 of the nut 3, which is the portion other than the crimping recess 35 and the accommodating hole 33.

[0019] (Rolling elements) As shown in FIG. 1, a plurality of rolling elements 4 are disposed between the nut 3 and the screw shaft 2. The rolling elements 4 are, for example, balls. When the nut 3 and the screw shaft 2 are assembled together, a spiral rolling path 40 is formed by an inner peripheral rolling groove 31 formed in the nut 3 and an outer peripheral rolling groove 25 formed in the screw shaft body 21. The rolling elements 4 move in this spiral rolling path 40. In FIG. 1, one rolling element 4 is indicated by a two-dot chain line. In reality, the ball screw 1 includes a plurality of rolling elements 4.

[0020] (frame) The tops 5 are accommodated in the respective accommodation holes 33 provided in the nut 3. Thus, in this embodiment, four tops 5 are provided. As shown in FIG. 5, the tops 5 are accommodated in the accommodation holes 33 from the radial outside of the nut 3. Each top 5 has a head 55 that abuts against the step portion 36 of the accommodation hole 33 and a circulation path 57 provided on the inner surface side. When the tops 5 are accommodated in the accommodation hole 33, the heads 55 of the tops 5 are formed so as to be flush with the outer circumferential surface of the nut 3, for example. In addition, when the tops 5 are accommodated in the accommodation hole 33, the heads 55 of the tops 5 may be formed so as to protrude radially outward from the outer circumferential surface of the nut 3, or may be formed so as to be recessed radially inward from the outer circumferential surface of the nut 3. As shown in FIG. 3, the circulation path 57 of the tops 5 connects one end and the other end of the spiral rolling path 40 to form an infinite circulation circuit. The infinite circulation circuit is filled with a plurality of rolling elements 4, so that the rolling elements 4 circulate infinitely within the infinite circulation circuit. In other words, the ball screw 1 of this embodiment is a so-called screw circulation type ball screw 1.

[0021] More specifically, the inner surface of the top 5 is curved with a curvature corresponding to the curved surface forming the inner peripheral surface of the nut 3, and is provided at the same height as the thread of the inner peripheral rolling groove 31. A groove-shaped circulation path 57 is formed on the inner surface of this top 5. The circulation path 57 is formed in a curved shape with a U-shaped cross section corresponding to the spherical surface of the rolling body 4. The circulation path 57 is greatly curved on the inner surface of the top 5, for example, in an S-shape. An inlet / outlet 58a at one end of the circulation path 57 is connected to one end of the inner peripheral rolling groove 31. An inlet / outlet 58b at the other end of the circulation path 57 is connected to the other end of the inner peripheral rolling groove 31. From one end to the other end of the inner peripheral rolling groove 31, the inner peripheral surface of the nut 3 makes approximately one revolution, and between the inlet / outlet 58a and the inlet / outlet 58b, there is one thread each of the thread of the nut 3 and the thread of the screw shaft 2. The circulation path 57 is gently curved in the axial and circumferential directions of the nut 3 so as to ride over the threads of the screw shaft 2 between the inlet / outlet 58a and the inlet / outlet 58b. In order to make it easier for the rolling elements 4 to ride over the threads of the screw shaft 2, the circulation path 57 is formed so that the amount of recession toward the radially outward increases toward the center of the link 5.

[0022] As a result, the rolling element 4 moves to one end of the inner rolling groove 31, changes its direction of travel through the inlet 58a, and enters the circulation path 57. The rolling element 4 that entered the circulation path 57 moves along the circulation path 57, overcomes one thread, changes its direction of travel, and moves to the other end of the inner rolling groove 31 through the inlet 58b. The rolling element 4 that moved to the other end of the inner rolling groove 31 makes one revolution around the inner surface of the nut 3 along the inner rolling groove 31, and then returns to one end of the inner rolling groove 31. The ball screw 1 of this embodiment has a plurality of infinite circulation circuits (four in this embodiment) each consisting of the inner rolling groove 31 (i.e., the rolling path 40) and the circulation path 57 in the link 5.

[0023] As shown in Fig. 2, in the following description, the four pieces 5 may be referred to as a first piece 51, a second piece 52, a third piece 53, and a fourth piece 54, respectively, from the first side in the axial direction. When there is no need to distinguish between these pieces, they may be simply referred to as pieces 5. The first to fourth pieces 51, 52, 53, and 54 are provided at different positions in the axial direction. The first to fourth pieces 51, 52, 53, and 54 may be provided at positions where they partially overlap each other in the axial direction.

[0024] (Cylindrical member) As shown in Figs. 1 and 2, the cylindrical member 6 is attached to the outer periphery of the nut 3 so as to surround the outer periphery of the nut 3. The cylindrical member 6 is, for example, a sleeve formed of a thin metal plate. The inner diameter dimension D2 of the cylindrical member 6 is equal to or larger than the outer dimension D1 of the nut 3. The cylindrical member 6 is attached to the nut 3 by, for example, a clearance fit. As shown in Figs. 1 and 4, a crimping portion 61 is provided at the end portion (one end portion in the claims) of the cylindrical member 6 on the second side in the axial direction. The crimping portion 61 is formed by crimping the end portion (the other end portion in the claims) of the cylindrical member 6 on the first side in the axial direction to the nut 3 in a state where the end portion (the other end portion in the claims) of the cylindrical member 6 on the first side in the axial direction is in contact with the pressing member 9 (see Fig. 8). The crimping portion 61 is fitted into the crimping recess 35 of the nut 3 by crimping. This allows the cylindrical member 6 to be positioned in the axial direction relative to the nut 3. As shown in Figs. 1 and 5, a flange portion 63 is provided at the end portion of the cylindrical member 6 on the first side in the axial direction. The flange portion 63 is formed by extending radially outward from an end portion of the cylindrical member 6. The flange portion 63 is integrally formed with the main body portion of the cylindrical member 6.

[0025] In a state where the cylindrical member 6 is attached to the nut 3, the cylindrical member 6 covers at least a part of the multiple links 5 from the radial outside. In this embodiment, the cylindrical member 6 covers the entire third link 53 and the fourth link 54 from the radial outside, and covers a part of the first link 51 and the second link 52 from the radial outside. That is, the axial length dimension of the cylindrical member 6 is smaller than the distance dimension from the first side end of the link located on the first side among the multiple links 5 (the first link 51 in this embodiment) to the second side end of the link located on the second side among the multiple links 5 (the fourth link 54 in this embodiment).

[0026] (Fitting parts) The fitting member 7 is provided on the outer peripheral surface of the nut 3 at a position that does not overlap with the cylindrical member 6 in the axial direction. In this embodiment, the fitting member 7 is provided on the first axial side of the cylindrical member 6. Therefore, in this embodiment, the cylindrical member 6 is provided between the fitting member 7 and the crimping recess 35 formed in the nut 3. The fitting member 7 is fitted to the outer peripheral portion of the nut 3. In this embodiment, the fitting member 7 is a bearing. The fitting member 7 may be, for example, a shielded bearing capable of sealing grease in the internal space. The fitting member 7 (i.e., the bearing) is attached to the nut 3 after the cylindrical member 6 is attached. The fitting member 7 is press-fitted and fixed into the nut 3. The end face of the fitting member 7 on the first axial side is arranged to be flush with the end face of the nut 3 on the first axial side. When the fitting member 7 is attached to the nut 3, the fitting member 7 covers at least a part of the multiple links 5 from the radial outside. In this embodiment, the fitting member 7 covers the portions of the first link 51 and the second link 52 that are not covered by the cylindrical member 6 from the outside in the radial direction.

[0027] Therefore, all four links 5 are covered from the radial outside by the cylindrical member 6 or the fitting member 7. In this embodiment, the entire area of ​​the head 55 of all four links 5 is covered by the cylindrical member 6 or the fitting member 7. In other words, when the cylindrical member 6 and the fitting member 7 are attached to the nut 3, the head 55 of the link 5 is not exposed. Also, in this embodiment, at least a portion of all four links 5 is covered by the cylindrical member 6. Therefore, by attaching the cylindrical member 6, it is possible to prevent the link 5 from falling off the nut 3.

[0028] 5, the fitting member 7 abuts against the flange portion 63 of the cylindrical member 6 in the axial direction. As described above, in this embodiment, the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 over the entire region of the nut 3 in the axial direction. In other words, the nut 3 is formed without having any protrusions or the like between the cylindrical member 6 and the fitting member 7 in the axial direction, the outer diameter of which is larger than the outer periphery (outer periphery main surface 30) of the nut 3 with which the cylindrical member 6 fits.

[0029] (Ball screw manufacturing method) Next, a method for manufacturing the above-mentioned ball screw 1 will be described. Fig. 6 is a flow diagram of the method for manufacturing the ball screw according to the first embodiment. Fig. 7 is an explanatory diagram of the method for manufacturing the ball screw according to the first embodiment. Fig. 8 is an explanatory diagram showing a state where the crimping step S10 in the method for manufacturing the ball screw according to the first embodiment has been completed. As shown in FIG. 6, the manufacturing method of the ball screw includes a nut forming step S02, a first state forming step S04, a retainer member arranging step S06, a cylindrical member arranging step S08, a crimping step S10, and a jig removing step S12.

[0030] 3 and 6, in the nut forming step S02, a nut 3 having an inner peripheral rolling groove 31, a plurality of accommodating holes 33, and a crimping recess 35 is formed. In the nut forming step S02, the nut 3 is formed such that the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 at least in a region of the nut 3 on the first axial side of the crimping portion 61 of the cylindrical member 6. Particularly in the nut forming step S02 of this embodiment, the nut 3 is formed such that the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 over the entire region of the nut 3 in the axial direction.

[0031] After the nut forming step S02, a first state forming step S04 is performed. In the first state forming step S04, the nut 3 formed in the nut forming step S02 and the top 5 are assembled to form the ball screw 10 in a first state. In other words, the ball screw 10 in the first state refers to a ball screw in a state in which the nut 3 and the top 5 are assembled and the cylindrical member 6 and the fitting member 7 are not assembled. Note that Figs. 7 and 8 show the ball screw 1 in a state after the cylindrical member 6 and the fitting member 7 are assembled to the ball screw 10 in the first state.

[0032] As shown in Fig. 7, after the first state forming step S04, a pressing member arranging step S06 is performed. In the pressing member arranging step S06, a pressing member 9 is arranged on the ball screw 10 in the first state. In the pressing member arranging step S06, the pressing member 9 is arranged so that an end face of the pressing member 9 is arranged at a predetermined axial position P1 on the ball screw 10 in the first state. The predetermined position P1 is a position corresponding to a first axial end of the cylindrical member 6 when the cylindrical member 6 is crimped, for example, by a crimping step S10 described later. The predetermined position P1 is set in advance.

[0033] In this embodiment, the pressing member 9 includes the above-mentioned fitting member 7 (bearing in this embodiment) and a jig 8. In the pressing member arrangement step S06, first, the fitting member 7 is press-fitted and fixed to the outer periphery of the nut 3. At this time, the fitting member 7 is press-fitted so that the end face of the fitting member 7 on the second side in the axial direction is arranged at a predetermined position P1. Also, at this time, for example, the fitting member 7 may be press-fitted to a position where the end face of the fitting member 7 on the first side in the axial direction and the end face of the nut 3 on the first side in the axial direction are flush with each other. Next, the jig 8 is arranged on the first side in the axial direction of the fitting member 7. The jig 8 is formed, for example, in a cylindrical shape, and is configured so that a part of the ball screw 1 can be inserted into its inner periphery. The jig 8 is arranged to support at least the fitting member 7 from the axial direction. The jig 8 suppresses the fitting member 7 from moving to the first side in the axial direction, for example, by abutting against the end faces of the fitting member 7 and the nut 3 on the first side in the axial direction.

[0034] Next, after the pressing member arrangement step S06, a cylindrical member arrangement step S08 is performed. In the cylindrical member arrangement step S08, the cylindrical member 6 is fitted onto the outer periphery of the nut 3 of the ball screw 10 in the first state, and the cylindrical member 6 is moved until the end of the cylindrical member 6 on the first side in the axial direction is arranged at a position that substantially coincides with the predetermined position P1. The order of the pressing member arrangement step S06 and the cylindrical member arrangement step S08 may be reversed. That is, the cylindrical member 6 may be fitted onto the outer periphery of the nut 3 first, and then the pressing member 9 (specifically, the fitting member 7 and the jig 8) may be arranged.

[0035] Next, after the cylindrical member arrangement step S08, a crimping step S10 is performed. In the crimping step S10, a load is applied to the end of the cylindrical member 6 on the second axial side arranged on the outer periphery of the nut 3, and the end of the cylindrical member 6 is crimped to the nut 3. As shown in Figs. 7 and 8, in the crimping step S10, for example, a cylindrical crimping jig 82 is inserted into the cylindrical member 6 from the second axial side. A curved portion 83 whose inner diameter increases from the second axial side to the first axial side is formed at the corner of the inner peripheral surface of the crimping jig 82. The curved portion 83 is pressed against the end of the cylindrical member 6 from the axial direction to form a crimped portion 61 (see Fig. 8) at the end of the cylindrical member 6. In this way, in the crimping step S10, a load including a directional component along the first axial side is applied to the end of the cylindrical member 6 on the second axial side. In the crimping step S10, the crimping process is performed in a state where the flange portion 63 of the cylindrical member 6 is in contact with the end face on the second axial side of the pressing member 9 (more specifically, the fitting member 7). Therefore, the impact load generated in the cylindrical member 6 during crimping can be borne by the pressing member 9 (fitting member 7). As a result, a crimped portion 61 is formed at the end portion on the second axial side of the cylindrical member 6. The crimped portion 61 engages with the crimped recess 35 of the nut 3, thereby positioning the cylindrical member 6 in the axial direction.

[0036] Next, after the crimping step S10, a jig removing step S12 is performed. In the jig removing step S12, the jig 8 and the crimping jig 82 are removed from the ball screw 1. Through the above steps, the ball screw 1 in which the cylindrical member 6 and the fitting member 7 are disposed on the outer periphery of the nut 3 is manufactured.

[0037] (Action, effect) According to the ball screw 1 of this embodiment, the ball screw 1 includes a cylindrical member 6 that is fitted to the nut 3 by having one end (the end on the second side in the axial direction) swaged to the outer periphery of the nut 3 and that covers the top 5 from the outside in the radial direction. The cylindrical member 6 is attached to the outer periphery of the nut 3 by swaging, so that the dislodging of the top 5 can be suppressed by a simple configuration. In a region on the first axial side from the other end (the end on the first axial side) of the cylindrical member 6, the outer diameter dimension D1 of the nut 3 is formed to be equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6. As a result, the nut 3 is formed without having a protruding portion such as a flange at a position corresponding to the end on the first axial side of the cylindrical member 6. Therefore, compared to the conventional technology using a nut 3 having a protruding portion such as a flange at a position corresponding to the end on the first axial side of the cylindrical member 6, an increase in the manufacturing cost of the nut 3 can be suppressed. Furthermore, since there is no need to secure an extra axial length of the nut 3 in order to provide a protruding portion such as a flange, an increase in the size of the nut 3 in the axial direction can be suppressed. Therefore, it is possible to provide a ball screw 1 that can suppress an increase in size while suppressing an increase in manufacturing costs.

[0038] The cylindrical member 6 has a crimping portion 61 that fits into the crimping recess 35 of the nut 3. The crimping portion 61 is formed by crimping the cylindrical member 6 to the nut 3 with the end of the cylindrical member 6 on the first side in the axial direction in contact with the pressing member 9. Since the pressing member 9 is provided at a position corresponding to the end of the cylindrical member 6 on the first side in the axial direction, the axial load during crimping can be supported by the pressing member 9. This allows the cylindrical member 6 to be crimped without providing a convex portion such as a flange on the nut 3. Therefore, in the ball screw 1 configured to fix the cylindrical member 6 to the nut 3 by crimping, the cylindrical member 6 can be fixed without forming a convex portion such as a flange on the outer periphery of the nut 3. Therefore, compared to the conventional technology using a nut 3 having a convex portion such as a flange, an increase in the manufacturing cost of the nut 3 and an increase in the size of the nut 3 can be suppressed.

[0039] The ball screw 1 includes a fitting member 7, and the cylindrical member 6 is provided between the fitting member 7 and the crimping recess 35 formed in the nut 3. This makes it possible to more effectively suppress the movement of the cylindrical member 6 in the axial direction. Since the fitting member 7 is disposed at a position corresponding to the end of the cylindrical member 6 on the first side in the axial direction, the axial load during crimping can be received by the fitting member 7. This makes it possible to crimp the cylindrical member 6 without providing a protruding portion such as a flange on the nut 3. In addition, since the fitting member 7, which is a component of the ball screw 1, can be used as a member that receives the load during crimping, an increase in the number of parts can be suppressed. Therefore, compared to the conventional technology in which a protruding portion such as a flange is provided on the nut 3, an increase in the manufacturing cost of the nut 3 and an increase in the size of the nut 3 can be suppressed. Furthermore, since the cylindrical member 6 and the fitting member 7 are formed without having a protruding portion such as a flange between them in the axial direction, the distance between the cylindrical member 6 and the fitting member 7 can be shortened. Therefore, the increase in the size of the nut 3 in the axial direction can be further suppressed.

[0040] The outer diameter dimension D1 of the nut 3 is formed to be equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 throughout the entire axial region of the nut 3. This makes it possible to more effectively prevent an increase in the manufacturing cost of the nut 3. Also, it is possible to prevent the nut 3 from becoming large in size in the axial direction.

[0041] According to the manufacturing method of the ball screw of this embodiment, the manufacturing method of the ball screw includes a nut forming step S02, a first state forming step S04, a pressing member arranging step S06, a cylindrical member arranging step S08, and a crimping step S10. In the nut forming step S02, the nut 3 is formed such that the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 in a region of the nut 3 on the first axial side of the crimping portion 61 of the cylindrical member 6. That is, the nut 3 is formed without having a protruding portion such as a flange at a position corresponding to the end of the cylindrical member 6 on the first axial side. Therefore, compared with the conventional technology in which the nut 3 having a protruding portion such as a flange at a position corresponding to the end of the cylindrical member 6 on the first axial side is formed, an increase in the manufacturing cost of the nut 3 can be suppressed. In addition, since it is not necessary to secure an extra axial length of the nut 3 in order to provide a protruding portion such as a flange, an increase in the size of the nut 3 in the axial direction can be suppressed. Therefore, it is possible to provide a manufacturing method for the ball screw 1 that can suppress an increase in size while suppressing an increase in manufacturing costs. In the crimping step S10, the cylindrical member 6 is crimped in a state where it is butted against the pressing member 9 arranged at a position corresponding to the end of the cylindrical member 6 on the first side in the axial direction. Therefore, the pressing member 9 can bear the butting load when the cylindrical member 6 is crimped. Therefore, even if no protrusion such as a flange is formed on the outer periphery of the nut 3, the cylindrical member 6 can be easily fixed by crimping.

[0042] The pressing member 9 includes a fitting member 7 and a jig 8 that supports the fitting member 7 at a predetermined position P1. In the crimping process S10, the end face of the second axial side of the cylindrical member 6 is crimped while the end face of the first axial side of the cylindrical member 6 is in contact with the fitting member 7. This allows the fitting member 7 to bear the impact load when the cylindrical member 6 is crimped. Therefore, the cylindrical member 6 can be crimped without forming a protrusion such as a flange on the outer periphery of the nut 3. Therefore, compared to the conventional technology in which a protrusion such as a flange is provided on the nut 3, an increase in the manufacturing cost of the nut 3 and an increase in the size of the nut 3 can be suppressed.

[0043] In the nut forming step S02, the nut 3 is formed so that the outer diameter dimension D1 of the nut 3 is equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 over the entire axial region of the nut 3. This makes it possible to more effectively suppress an increase in the manufacturing cost of the nut 3. Also, it is possible to suppress an increase in the size of the nut 3 in the axial direction.

[0044] Next, second to fourth embodiments of the present invention will be described with reference to Figs. 9 to 11. In the description of the second to fourth embodiments, the same components as those in the first embodiment described above will be denoted by the same reference numerals and will not be described as necessary. Note that the specific components are not limited to these embodiments and can be modified as appropriate without departing from the gist of the present invention. Figs. 9 to 10 show a ball screw in a state where the crimping step S10 has been completed.

[0045] Second embodiment 9 is an explanatory diagram of a manufacturing method of a ball screw according to the second embodiment. The second embodiment differs from the above-described first embodiment in that the pressing member 9 does not have a fitting member 7.

[0046] In the second embodiment, the method for manufacturing the ball screw includes the nut forming step S02, the first state forming step S04, the pressing member arranging step S06, the cylindrical member arranging step S08, the crimping step S10, and the jig removing step S12 of the first embodiment described above. The nut forming step S02, the first state forming step S04, and the cylindrical member arranging step S08 are the same as those of the first embodiment, and therefore will not be described. In the second embodiment, the pressing member 9 is a jig 208 capable of holding the ball screw 10 in the first state. In the pressing member arranging step S06 of the second embodiment, the jig 208 is arranged so that an end face of the jig 208 is arranged at a predetermined axial position P1 of the ball screw 10 in the first state. The jig 208 is formed in a cylindrical shape having a first inner circumferential portion 11, a second inner circumferential portion 12 into which a part of the nut 3 is inserted, and a step portion 13 provided between the first inner circumferential portion 11 and the second inner circumferential portion 12 and abutting against an end face of the nut 3 on the first side in the axial direction. The dimensions of the jig 208 are set so that the end portion on the second axial side is located at a predetermined position P1 when the step portion 13 abuts against the nut 3. The first inner circumferential portion 11 may be omitted.

[0047] In the crimping step S10 of the second embodiment, the cylindrical member 6 is crimped with the end portion on the first axial side of the cylindrical member 6 abutting against the end face on the second axial side of the jig 208. This forms the crimped portion 61. The method of forming the crimped portion 61 may be the same as that of the first embodiment, for example. In the jig removal step S12, the jig 208 and the crimping jig 82 (see FIG. 7) are removed from the ball screw 1. Through the above steps, the ball screw 201 in which the cylindrical member 6 is disposed on the outer periphery of the nut 3 is manufactured.

[0048] According to the ball screw 201 and the manufacturing method of the ball screw of the second embodiment, for example, it is possible to manufacture a ball screw 201 that does not have a fitting member 7. In addition, it is possible to achieve the same effects as the first embodiment. That is, compared to the conventional technology in which a nut 3 having a protrusion such as a flange at a position corresponding to the end of the first side in the axial direction of the cylindrical member 6 is formed, it is possible to suppress an increase in the manufacturing cost of the nut 3. In addition, since it is not necessary to secure an extra axial length of the nut 3 in order to provide a protrusion such as a flange, it is possible to suppress an increase in the size of the nut 3 in the axial direction. Therefore, it is possible to provide a manufacturing method for a ball screw that can suppress an increase in manufacturing cost while suppressing an increase in size. Furthermore, in the crimping step S10, the cylindrical member 6 is crimped in a state where it is butted against the jig 208, which is the pressing member 9. Therefore, even if the fitting member 7 is not provided, the jig 208 can bear the butting load when the cylindrical member 6 is crimped. Therefore, the cylindrical member 6 can be easily fixed by crimping without forming a protrusion such as a flange on the outer periphery of the nut 3.

[0049] In the second embodiment, a fitting member arrangement step may be further provided after the jig removal step S12. In the fitting member arrangement step, for example, as shown by a dashed line in FIG. 9, after removing the jig 208, the fitting member 7 that fits on the outer periphery of the nut 3 is arranged at the location of the outer periphery of the nut 3 where the jig 208 was attached. In addition, at this time, the fitting member 7 may be attached so that the end face of the first axial side of the attached fitting member 7 and the end face of the nut 3 are flush with each other. In this case, the ball screw 1 having the fitting member 7 is manufactured in the same manner as in the first embodiment. Thereby, the fitting member 7 can be attached after the cylindrical member 6. Therefore, the versatility of the manufacturing method of the ball screw can be improved.

[0050] Third embodiment Next, a third embodiment of the present invention will be described. 10 is an explanatory diagram of a manufacturing method of a ball screw according to the third embodiment. In the third embodiment, the position at which the fitting member 7 is attached is different from that in the first embodiment described above.

[0051] In the third embodiment, the fitting member 7 is disposed so that the end face of the fitting member 7 on the second axial side coincides with a predetermined position P2. At this time, the end face of the fitting member 7 on the first axial side is disposed at a position spaced a distance H from the end face of the nut 3. Similarly to the second embodiment, the jig 308 has a first inner circumferential portion 11, a second inner circumferential portion 12, and a step portion 13. With the step portion 13 of the jig 308 in contact with the end face of the nut 3, the end portion of the jig 308 on the second axial side and the end face of the fitting member 7 on the first axial side come into contact with each other.

[0052] According to the ball screw 301 and the manufacturing method of the ball screw of the third embodiment, it is possible to obtain the same advantageous effects as those of the first embodiment. In addition, the fitting member 7 can be disposed at any position. Therefore, it is possible to increase the versatility of the manufacturing method of the ball screw.

[0053] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. 11 is an explanatory diagram of a manufacturing method of a ball screw according to the fourth embodiment. The fourth embodiment differs from the above-described third embodiment in that a ball screw 401 does not have a fitting member 7.

[0054] In the fourth embodiment, the pressing member 9 is a jig 408. In other words, the pressing member 9 does not include a fitting member 7. In the pressing member arrangement step S06 of the fourth embodiment, similarly to the second embodiment, the jig 408 is arranged so that an end face of the jig 408 is arranged at a predetermined axial position P2 of the ball screw 10 in the first state. The jig 408 may be formed in, for example, a shape equivalent to that of the jig 208 of the second embodiment.

[0055] According to the ball screw 401 and the manufacturing method of the ball screw of the fourth embodiment, it is possible to obtain the same advantageous effects as those of the second embodiment, and therefore it is possible to increase the versatility of the manufacturing method of the ball screw. In the fourth embodiment, a fitting member arranging step may be further provided after the jig removing step S12, as in the second embodiment. In the fitting member arranging step, for example, as shown by a dashed line in FIG. 11, a fitting member 7 that fits on the outer periphery of the nut 3 is arranged at a location on the outer periphery of the nut 3 where the jig 408 was attached. In addition, at this time, the fitting member 7 may be attached so that the end face of the first axial side of the attached fitting member 7 and the end face of the nut 3 are separated in the axial direction. In this case, a ball screw 401 having a fitting member 7 is manufactured, as in the third embodiment. Therefore, the versatility of the manufacturing method of the ball screw can be improved.

[0056] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the fitting member 7 is fixed to the nut 3 by press-fitting, but this is not limiting. The fitting member 7 may be attached to the nut 3 by clearance fit. In this case, the fitting member 7 may be positioned in the axial direction by the cylindrical member 6 and another part (not shown) attached to, for example, the connecting shaft 22 of the screw shaft 2.

[0057] In each embodiment, the flange portion 63 may not be formed on the first axial side of the cylindrical member 6. In this case, the end of the cylindrical member 6 on the first axial side and the pressing member 9 may simply come into contact with each other by abutting. In addition, when the fitting member 7 is attached later as in the second and fourth embodiments, for example, the cylindrical member 6 and the fitting member 7 may be disposed apart from each other in the axial direction.

[0058] The fitting member 7 may be omitted. Alternatively, the fitting member 7 may include a plurality of parts. For example, the fitting member 7 may include two or more bearings. For example, the fitting member 7 may include a plurality of types of parts different from the cylindrical member 6, such as bearings and gears. The outer circumferential rolling groove 25 may be provided on a part of the outer circumferential part of the screw shaft body 21. Similarly, the inner circumferential rolling groove 31 may be provided on a part of the inner circumferential part of the nut 3. The number of the links 5 is not limited to the above-mentioned number. In the above-mentioned embodiment, some of the links 5 are covered by the fitting member, but this is not limited to the above. All of the links 5 may be covered by the cylindrical member 6. In the above embodiment, for example, in Fig. 1 and the like, the fitting member 7 is illustrated as a ball bearing as an example of the bearing, but is not limited thereto. The fitting member 7 may be a roller bearing, a conical bearing, or the like. In the above embodiment, the nut 3 rotates and the screw shaft 2 moves in the axial direction, but the present invention is not limited to this. The present invention may be applied to a type of ball screw in which the screw shaft 2 rotates and the nut 3 moves in the axial direction. In this case, the nut 3 does not need to be provided with a bearing as the fitting member 7.

[0059] Instead of the curved portion 83, a sloping portion may be provided at the corners of the inner peripheral surface of the crimping jig 82 such that the inner diameter increases from the second side toward the first side in the axial direction. The shapes of the jig 8 and the crimping jig 82 are not limited to a cylindrical shape. The crimping jig 82 may have a plurality of curved portions 83 arranged discontinuously in the circumferential direction. In this case, the crimping portions 61 may be formed in a plurality of discontinuously arranged in the circumferential direction.

[0060] The cylindrical member 6 may be attached by being pressed into the outer periphery of the nut 3. Here, it is sufficient that the outer diameter dimension D1 of at least the part of the nut 3 to which the cylindrical member 6 is attached is formed to be equal to or smaller than the inner diameter dimension D2 of the cylindrical member 6 when the cylindrical member 6 is attached to at least the outer periphery of the nut 3. That is, when the cylindrical member 6 is configured to be pressed into, the inner diameter dimension D2 of the cylindrical member 6 before assembly may be smaller than the outer diameter dimension D1 of the nut 3 before assembly. Alternatively, when the cylindrical member 6 is configured to be pressed into, the outer diameter of the part of the nut 3 to which the cylindrical member 6 is attached may differ from the outer diameter of the part of the nut 3 to which the cylindrical member 6 is not attached. As a result, even when the cylindrical member 6 is attached to the outer periphery of the nut 3, the inner diameter dimension D2 of the cylindrical member 6 may be smaller than the outer diameter of the part of the nut 3 to which the cylindrical member 6 is not attached. The present invention includes various dimensions within a certain error range when the cylindrical member 6 is pressed into in this manner. In other words, the statement in the claim that "the outer diameter dimension of the nut is formed to be equal to or smaller than the inner diameter dimension of the cylindrical member" includes the inner diameter dimension D2 of the cylindrical member 6 and the outer diameter dimension D1 of the nut 3 being the same, and "same" does not only mean completely the same, but also includes being substantially the same within a certain error range.

[0061] The present disclosure may also be implemented in the following combinations: (1) A screw shaft having a spiral outer circumferential rolling groove on an outer circumferential surface thereof; A nut having a spiral inner peripheral rolling groove on an inner peripheral surface thereof; A plurality of rolling elements are disposed in a rolling path formed by the inner peripheral rolling groove of the nut and the outer peripheral rolling groove of the screw shaft; a nut having a circulation path for returning the rolling elements from one end of the rolling path to the other end; a cylindrical member having one end fitted to the nut by being tightened to an outer periphery of the nut to cover the link from the outside in the radial direction; Equipped with In a region opposite to the one end in the axial direction of the screw shaft from the other end of the cylindrical member, the outer diameter dimension of the nut is formed to be equal to or smaller than the inner diameter dimension of the cylindrical member. Ball screw. (2) the cylindrical member has a crimped portion formed by crimping the nut with the other end of the cylindrical member in contact with a pressing member, The nut has a crimping recess into which the crimping portion fits. A ball screw as described in (1). (3) The nut further includes a fitting member that is provided without overlapping with the cylindrical member in the axial direction and that fits into an outer periphery of the nut, The cylindrical member is provided between the crimping recess formed in the nut and the fitting member. (2) A ball screw as described above. (4) The outer diameter dimension of the nut is formed to be equal to or smaller than the inner diameter dimension of the cylindrical member over the entire region of the nut in the axial direction. A ball screw according to any one of (1) to (3). (5) A method for manufacturing a ball screw according to any one of (1) to (4) above, a nut forming step of forming the nut such that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member in a region of the nut that is closer to the cylindrical member in the axial direction than the crimping portion of the cylindrical member; a first state forming step of forming a ball screw in a first state in which the formed nut and the top are assembled; a pressing member arranging step of arranging a pressing member so that an end face of the pressing member is arranged at a predetermined position in the axial direction of the ball screw in the first state; a cylindrical member positioning step of extrapolating the cylindrical member onto an outer periphery of the nut in the first state of the ball screw and moving the cylindrical member so that the other end of the cylindrical member in the axial direction is positioned at the predetermined position; a crimping process in which a load having at least the axial component is applied to the other axial end of the cylindrical member disposed on the outer periphery of the nut, thereby crimping the one end of the cylindrical member to the outer periphery of the nut; Equipped with A method for manufacturing a ball screw. (6) The holding member is A fitting member that is fitted to an outer periphery of the nut and attached to the nut; a jig that supports the fitting member in the axial direction with the end surface of the fitting member disposed at the predetermined position; Including, In the crimping step, the one end of the cylindrical member is crimped in a state in which the other end of the cylindrical member is in contact with the end surface of the fitting member. (5) A method for manufacturing the ball screw according to the present invention. (7) the pressing member is a jig for holding the ball screw in the first state so that an end surface of the pressing member is disposed at the predetermined position, In the crimping step, the one end of the cylindrical member is crimped in a state in which the other end of the cylindrical member is in contact with the end surface of the jig. A method for manufacturing a ball screw according to (5) or (6). (8) a jig removing step of removing the jig from the ball screw after the crimping step; After the jig removal step, a fitting member arrangement step of arranging a fitting member that fits onto the outer periphery of the nut at the location of the outer periphery of the nut where the jig was attached; Further comprising: A method for manufacturing a ball screw according to (7). (9) In the nut forming step, the nut is formed so that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member over the entire region of the nut in the axial direction. A method for manufacturing a ball screw according to any one of (5) to (8). [Explanation of symbols]

[0062] 1,201,301,401 Ball screw 2 Screw shaft 3 Nut 4 Rolling elements 5 frames 6 Cylindrical members 7 Fittings 8,208,308,408 Jig 9 Retaining member 10 Ball screw in first state 25 Outer periphery rolling groove 31 Inner circumference rolling groove 35 Crimping recess 40 Rolling Path 57 Circulation route 61 Crimping part D1 Nut external dimensions D2 Inner diameter of cylindrical part P1, P2 designated position

Claims

1. A screw shaft having a spiral outer circumferential rolling groove on an outer circumferential surface thereof; A nut having a spiral inner peripheral rolling groove on an inner peripheral surface thereof; A plurality of rolling elements are disposed in a rolling path formed by the inner peripheral rolling groove of the nut and the outer peripheral rolling groove of the screw shaft; a nut having a circulation path for returning the rolling elements from one end of the rolling path to the other end; a cylindrical member having one end fitted to the nut by being tightened to an outer periphery of the nut to cover the link from the outside in the radial direction; Equipped with In a region opposite to the one end in the axial direction of the screw shaft from the other end of the cylindrical member, the outer diameter dimension of the nut is formed to be equal to or smaller than the inner diameter dimension of the cylindrical member. Ball screw.

2. the cylindrical member has a crimped portion formed by crimping the nut with the other end of the cylindrical member in contact with a pressing member, The nut has a crimping recess into which the crimping portion fits.

2. The ball screw according to claim 1.

3. The nut further includes a fitting member that is provided without overlapping with the cylindrical member in the axial direction and that fits into an outer periphery of the nut, The cylindrical member is provided between the crimping recess formed in the nut and the fitting member.

3. The ball screw according to claim 2.

4. The outer diameter dimension of the nut is formed to be equal to or smaller than the inner diameter dimension of the cylindrical member over the entire region of the nut in the axial direction. The ball screw according to any one of claims 1 to 3.

5. A screw shaft having a spiral outer circumferential rolling groove on an outer circumferential surface thereof; A nut having a spiral inner peripheral rolling groove on an inner peripheral surface thereof; A plurality of rolling elements are disposed in a rolling path formed by the inner peripheral rolling groove of the nut and the outer peripheral rolling groove of the screw shaft; a nut having a circulation path for returning the rolling elements from one end of the rolling path to the other end; a cylindrical member having a crimping portion attached to an outer periphery of the nut at one end in an axial direction and covering the top from the outside in a radial direction; A manufacturing method of a ball screw comprising: a nut forming step of forming the nut such that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member in a region of the nut that is closer to the cylindrical member in the axial direction than the crimping portion of the cylindrical member; a first state forming step of forming a ball screw in a first state in which the formed nut and the top are assembled; a pressing member arranging step of arranging a pressing member so that an end face of the pressing member is arranged at a predetermined position in the axial direction of the ball screw in the first state; a cylindrical member positioning step of extrapolating the cylindrical member onto an outer periphery of the nut in the ball screw in the first state and moving the cylindrical member so that the other end of the cylindrical member in the axial direction is positioned at the predetermined position; a crimping process in which a load having at least the axial component is applied to the one end of the cylindrical member disposed on the outer periphery of the nut in the axial direction, thereby crimping the other end of the cylindrical member to the outer periphery of the nut; Equipped with A method for manufacturing a ball screw.

6. The holding member is A fitting member that is fitted to an outer periphery of the nut and attached to the nut; a jig that supports the fitting member in the axial direction with the end surface of the fitting member disposed at the predetermined position; Including, In the crimping step, the one end of the cylindrical member is crimped in a state in which the other end of the cylindrical member is in contact with the end surface of the fitting member. A method for manufacturing a ball screw according to claim 5.

7. the pressing member is a jig for holding the ball screw in the first state so that an end surface of the pressing member is disposed at the predetermined position, In the crimping step, the one end of the cylindrical member is crimped in a state in which the other end of the cylindrical member is in contact with the end surface of the jig. A method for manufacturing a ball screw according to claim 5.

8. a jig removing step of removing the jig from the ball screw after the crimping step; After the jig removal step, a fitting member arrangement step of arranging a fitting member that fits onto the outer periphery of the nut at the location of the outer periphery of the nut where the jig was attached; Further comprising: A method for manufacturing a ball screw according to claim 7.

9. In the nut forming step, the nut is formed so that an outer diameter dimension of the nut is equal to or smaller than an inner diameter dimension of the cylindrical member over the entire region of the nut in the axial direction. The method for manufacturing a ball screw according to any one of claims 5 to 8.

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