Method for manufacturing ball screws, ball screw nuts, and ball screw sockets

Abstract

The present invention provides a method for manufacturing a ball screw and a ball screw nut, and a ball screw nut, which can improve the workability of attaching the nut compared to conventional technology while suppressing an increase in the number of parts. [Solution] The ball screw nut comprises a nut body 7 and a spool 8 attached to a housing hole 22 formed in the nut body 7, forming a circulation path. The spool 8 comprises a spool body having a circulation path and an arm portion. The arm portion protrudes from the spool body and is locked to the nut body 7, thereby restricting the spool 8 from falling out radially outward from the housing hole 22. The housing hole 22 comprises a first region 23 and a second region 24. The first region 23 houses the spool 8 in a state where its falling out radially outward is restricted by the arm portion. The second region 24 communicates with the first region 23 and is formed to be larger than the outer shape of the spool 8 in a front view when viewed from the radial direction of the nut.

Description

Technical Field

[0005]

[0001] The present invention relates to a ball screw, a method for manufacturing a nut for a ball screw, and a washer for a ball screw.

Background Art

[0002] Conventionally, in a ball screw having a nut, a screw shaft, and a plurality of rolling elements, as one of the circuit structures for circulating the plurality of rolling elements, a return path (circulation path) formed on the inner peripheral surface of the nut is provided separately from the groove for the main path (rolling path). A structure having a groove is known.

[0003] For example, Patent Document 1 discloses a washer-type ball screw including a screw shaft, a plurality of rolling elements, a nut having a washer in which a circulation path for returning the rolling elements from the end point to the start point of the rolling path is formed, and a sleeve for preventing the washer from coming off. Patent Document 2 also discloses a nut for a washer-type ball screw. The washer has a configuration including an arm engaged with the screw groove of the nut and a convex portion having a diameter larger than that of the piece window formed in the nut body. According to the technique described in Patent Document 2, after inserting the washer into the piece window from the inner side in the radial direction of the nut body and positioning the washer, the washer can be press-fitted and fixed to the nut body by elastically deforming the convex portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, the prior art described in Patent Document 1 and Patent Document 2, etc., had problems in suppressing the increase in the number of parts and improving the workability related to the installation of the ball screws.

[0007] Therefore, the present invention aims to provide a ball screw, a ball screw nut, and a ball screw nut that can improve the workability related to the installation of the nut compared to the conventional technology, while suppressing an increase in the number of parts. [Means for solving the problem]

[0008] To solve the above problems, this invention proposes the following means. A ball screw according to a first aspect of the present invention comprises a screw shaft having a helical outer circumferential rolling groove on its outer circumferential surface, a nut having a helical inner circumferential rolling groove on its inner circumferential surface, and 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, wherein the nut comprises a nut body and a spool attached to a housing hole formed in the nut body, forming a circulation path that returns the rolling elements from one end to the other of the rolling path, wherein the spool comprises a spool body having the circulation path and an arm portion protruding from the spool body and being locked to the nut body to prevent it from falling radially outward from the housing hole, wherein the housing hole comprises a first region that houses the spool in a state where its radial outward falling is restricted by the arm portion, and a second region communicating with the first region and formed to be larger than the outer shape of the spool in a front view when viewed from the radial direction of the nut.

[0009] A method for manufacturing a ball screw nut according to a first aspect of the present invention comprises a nut body having a spiral inner circumferential rolling groove on which a plurality of rolling elements roll, and a nut having a circulation path that returns the rolling elements from one end to the other end of the inner circumferential rolling groove, comprising a housing hole forming step of forming a housing hole in the nut body, and a nut mounting step of housing and mounting the nut in the housing hole, wherein the housing hole forming step comprises a first region in which the nut is housed with the arm portion of the nut locked to the nut body, and the first A receiving hole is formed having a second region that communicates with the first region and is formed to be larger than the outer shape of the piece in a front view when viewed from the radial direction of the nut, and the piece mounting step includes a piece insertion step of inserting the piece from the radial outside of the nut through the second region to the radial inside of the nut, and a piece receiving step of changing at least one of the position and orientation of the piece inserted inside the nut and pulling the piece up toward the radial outside to accommodate the piece in the first region.

[0010] A ball screw bearing according to a first aspect of the present invention is a ball screw bearing that is attached to a nut having a helical inner circumferential rolling groove on its inner circumferential surface and has a circulation path that returns the rolling element from one end to the other end of the inner circumferential rolling groove, comprising: a bearing body having the circulation path and being housed in a housing hole formed in the nut body; an arm portion protruding from the bearing body and being locked to the nut body to prevent it from falling out radially outward from the housing hole; and a handle portion provided on the bearing body opposite to the surface on which the arm portion is provided, which can be grasped by a robot arm when attaching the bearing to the nut body. [Effects of the Invention]

[0011] The present invention provides a method for manufacturing a ball screw, a ball screw nut, and a ball screw insert that can improve the workability of insert installation compared to the conventional technology while suppressing an increase in the number of parts. [Brief explanation of the drawing]

[0012] [Figure 1] A cross-sectional view of a ball screw according to the first embodiment. [Figure 2] A cross-sectional perspective view of a nut according to the first embodiment. [Figure 3] A perspective view of the frame according to the first embodiment. [Figure 4] A perspective view of the top according to the first embodiment, seen from the back side (inner side in the radial direction). [Figure 5] View of section V in Figure 1. [Figure 6] An explanatory diagram showing the process of inserting the spool. [Figure 7] An explanatory diagram showing the process of moving the spinning top. [Figure 8] An explanatory diagram showing the process of storing the frames. [Figure 9] A front view of the nut housing hole according to the second embodiment, viewed from the radially outer side. [Figure 10] A front view of the nut housing hole according to the third embodiment, viewed from the radially outer side.

Embodiments for Carrying out the Invention

[0013] Embodiments of the present invention will be described with reference to the drawings. In one embodiment, the ball screw 1 is incorporated into various mechanical devices such as an electric brake device of a vehicle, an automated manual transmission (AMT), and a positioning device of a machine tool, and converts the rotational motion of a drive source such as an electric motor into a linear motion to operate a driven part (operating part). As the electric brake device, various types such as an EMB (Electro-Mechanical Brake) that applies braking force through a ball screw driven by a motor, and an EHB (Electro-Hydraulic Brake) that controls the hydraulic pressure of a hydraulic brake through a ball screw driven by a motor are applicable. The ball screw 1 is also applicable to mechanical devices other than those described above.

[0014] In the following description, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction with respect to the central axis C of the ball screw 1 (nut 3) unless otherwise specified.

[0015] (First Embodiment) FIG. 1 is a cross-sectional view of the ball screw 1 according to the first embodiment. FIG. 2 is a cross-sectional perspective view of the nut 3 according to the first embodiment. In FIG. 1, a part of the inner circumferential rolling groove 20 formed in the nut 3 is shown with omission, but actually, in this embodiment, the inner circumferential rolling groove 20 is formed over the entire axial direction of the nut 3. Note that the inner circumferential rolling groove 20 may be formed only in a predetermined range in the axial direction as shown in FIG. 1.

[0016] In the ball screw 1 of this embodiment, for example, a nut 3 (the nut 3 for the ball screw in the claims) rotates about the central axis C. The nut 3 is rotatable about the central axis C and does not move in the 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 and is movable in the direction along the central axis C. When the nut 3 rotates, the screw shaft 2 moves in the direction along the central axis C.

[0017] The screw shaft 2 is formed in a columnar shape centered on the central axis C. The screw shaft 2 is disposed inside the nut 3 described later. A spiral outer circumferential rolling groove 6 is formed on the outer circumferential portion of the screw shaft 2. The cross-sectional shape of the outer circumferential rolling groove 6 is a Gothic arch including two arcs.

[0018] The nut 3 is formed in a cylindrical shape centered on the central axis C. The screw shaft 2 is inserted inside the nut 3 in the radial direction. A spiral inner circumferential rolling groove 20 is formed on the inner circumferential surface of the nut 3. The cross-sectional shape of the inner circumferential rolling groove 20 is a Gothic arch including two arcs. The inner circumferential rolling groove 20 is formed substantially over the entire length of the nut 3 in the axial direction. The detailed configuration of the nut 3 will be described later.

[0019] A plurality of rolling elements 4 are disposed between the screw shaft 2 and the nut 3. The rolling element 4 is, for example, a ball. In a state where the nut 3 and the screw shaft 2 are combined, a spiral rolling path 5 is formed by the inner circumferential rolling groove 20 formed in the nut 3 and the outer circumferential rolling groove 6 formed in the screw shaft 2. The rolling element 4 moves in this spiral rolling path 5. In FIG. 1, one rolling element 4 is indicated by a two-dot chain line. Actually, the ball screw 1 includes a plurality of rolling elements 4.

[0020] Next, the configuration of the nut 3 will be described in detail. As shown in Figures 1 and 2, the nut 3 comprises a cylindrical nut body 7 and one or more (two in this embodiment shown in Figure 1) ball screws 8 (ball screw 8 in the claim) attached to the nut body 7. As described above, a spiral inner circumferential rolling groove 20 is formed on the inner circumferential surface of the nut body 7. Furthermore, the nut body 7 has a plurality of housing holes 22 for accommodating the plurality of ball screws 8, which will be described in more detail later. Each housing hole 22 accommodates a ball screw 8.

[0021] Figure 3 is a perspective view of the link 8 according to the first embodiment. Figure 4 is a perspective view of the link 8 according to the first embodiment, viewed from the back side (inner radial direction). In the figures, "axial direction," "radial direction," and "circumferential direction" correspond to the axial direction, radial direction, and circumferential direction of the nut 3 when the link 8 is attached to the nut body 7. Since multiple links 8 are formed to be of the same shape, one link 8 will be described below.

[0022] As shown in Figures 3 and 4, the spinning top 8 has a spinning top body 31, an arm portion 32, and a handle portion 33. The spinning top 8 is made of, for example, synthetic resin. However, the spinning top 8 may also be made of metal or a mixed material in which resin and metal are insert-molded. The nut body 31 is housed and mounted in a housing hole 22 (more specifically, the first region 23 of the housing hole 22, which will be described later) formed in the nut body 7. When mounted on the nut body 7, the nut body 31 has a pair of side walls 41, 41 facing the circumferential direction of the nut 3 and a pair of side walls 42, 42 facing the axial direction, and is formed in a rectangular shape when viewed from the radial direction. In this embodiment, the nut body 31 is formed in a rectangular shape in which the distance between the pair of side walls 41, 41 facing each other in the circumferential direction is greater than the distance between the pair of side walls 42, 42 facing each other in the axial direction. Note that the shape of the nut body 31 is not limited to the shape of the embodiment described above.

[0023] A circulation path 35 is formed on the radially inward-facing surface (inner circumferential surface 43) of the ball body 31. As shown in Figure 2, the circulation path 35 connects one end 5a and the other end 5b of the helical rolling path 5 formed by the nut body 7 and the screw shaft 2, forming an infinite circulation circuit. Multiple rolling elements 4 are then filled into this infinite circulation circuit, causing the rolling elements 4 to circulate infinitely within the circuit. In other words, the ball screw 1 of this embodiment is a so-called ball screw of the ball type. More specifically, the inner circumferential surface 43 of the ball 8 is curved with a curvature corresponding to the curved surface forming the inner circumferential surface of the nut body 7, and is positioned at the same height as the threads of the inner circumferential rolling groove 20. Note that the inner circumferential surface 43 of the ball 8 and the threads of the inner circumferential rolling groove 20 may be formed at different heights. Furthermore, it is preferable that the center of the nut 3 (central axis C) and the center of the radius of curvature of the inner circumferential surface 43 of the ball 8 coincide.

[0024] The circulation path 35 provided on the inner circumferential surface 43 of the nut 8 is formed in a curved shape with a U-shaped cross-section corresponding to the spherical surface of the rolling element 4. The circulation path 35 is greatly curved on the inner circumferential surface 43 of the nut 8, for example, in an S-shape. An inlet / outlet 35a at one end of the circulation path 35 is connected to one end 5a of the inner circumferential rolling groove 20. An inlet / outlet 35b at the other end of the circulation path 35 is connected to the other end 5b of the inner circumferential rolling groove 20. The inner circumferential rolling groove 20 makes approximately one turn along the inner circumferential surface of the nut 3 from one end 5a to the other end 5b, and there is one thread of the screw shaft 2 between the inlet / outlet 35a and the inlet / outlet 35b. The circulation path 35 is gently curved in the axial and circumferential directions of the nut 3 so as to overcome the thread of the screw shaft 2 between the inlet / outlet 35a and the inlet / outlet 35b. Furthermore, in order to make it easier for the rolling elements 4 to overcome the threads of the screw shaft 2, the circulation path 35 is formed such that the amount of radial outward recess increases as it approaches the center in the circulation direction of the rolling elements 4.

[0025] As a result, the rolling element 4 moves to one end 5a of the inner circumferential rolling groove 20, then changes direction of travel through the entrance / exit 35a and enters the circulation path 35. Once inside the circulation path 35, the rolling element 4 moves along the circulation path 35, crossing one screw thread and changing direction of travel, then moves to the other end 5b of the inner circumferential rolling groove 20 through the entrance / exit 35b. After moving to the other end 5b of the inner circumferential rolling groove 20, the rolling element 4 travels around the inner surface of the nut body 7 along the inner circumferential rolling groove 20 once, and then returns to the one end 5a of the inner circumferential rolling groove 20 again. The ball screw 1 of this embodiment has multiple infinite circulation circuits consisting of such inner circumferential rolling grooves 20 (i.e., rolling paths 5) and circulation paths 35 of the ball screw 8.

[0026] As shown in Figures 2 to 4, a pair of arm portions 32 are provided, connected to the nut body 31. The arm portions 32 gradually rise radially inward as they extend circumferentially outward from the inner circumferential surface 43 of the nut body 31, and each protrudes circumferentially outward from the pair of side walls 41, 41 of the nut body 31. Each arm portion 32 is formed near the corner between the side walls 41 and 42 when viewed from the radially outward side. As shown in Figure 2, when the nut 8 is attached to the nut body 7, the arm portions 32 are locked to the nut body 7 by engaging (positioning) with the inner circumferential rolling grooves 20 of the nut body 7. The arm portions 32 engage with the inner circumferential rolling grooves 20 (one end 5a and the other end 5b of the inner circumferential rolling groove 20) that are connected to the circulation path 35 and with adjacent inner circumferential rolling grooves 20. The arm portion 32 engages with the inner circumferential rolling groove 20, thereby preventing the ball screw 8 from coming loose (falling out) radially outward from the housing hole 22 of the nut body 7. Therefore, the ball screw 1 of this embodiment is formed without a sleeve or the like on the outer circumference of the nut 3 to prevent the ball screw 8 from coming loose radially outward. As shown in Figures 2 to 4, the portion of the arm portion 32 that engages with the inner circumferential rolling groove 20 of the nut body 7 is formed in a cylindrical shape having an arc surface that follows the groove shape of the inner circumferential rolling groove 20. A gap may be provided between the arm portion 32 and the inner circumferential rolling groove 20.

[0027] As shown in Figures 1 and 3, a handle portion 33 is formed on the radially outward-facing surface (outer peripheral surface 44) of the nut body 31. The handle portion 33 is connected to the nut body 31. In this embodiment, the handle portion 33 protrudes radially outward from the nut body 31. The handle portion 33 extends along the circumferential direction. As shown in Figure 1, when the nut 8 is attached to the nut body 7, the top of the handle portion 33 and the outer peripheral surface of the nut body 7 are formed to be at the same height radially. The handle portion 33 is the part that is grasped by a robot arm 19 for nut attachment (see Figure 6) or by human hand when attaching the nut 8 to the nut body 7. The height of the top of the handle portion 33 may be higher or lower than the outer peripheral surface of the nut body 7.

[0028] Figure 5 is a view of section V in Figure 1, showing the receiving hole 22 formed in the nut body 7 as seen from the radial outside. In Figure 5, the link 8 is shown with a dashed line for explanatory purposes. As shown in Figures 1 and 5, the housing hole 22 penetrates the nut 3 radially. The housing hole 22 has a first region 23 and a second region 24, which are distinguished from each other according to their roles or functions. As shown in Figure 5, the first region 23 is formed in a rectangular shape with the circumferential direction as the long axis when viewed from the radial direction. The first region 23 is formed to be the same size as the outer shape of the spindle body 31 when viewed from the radial direction. In this specification, when "outer shape" of an object is referred to, it refers to the shape of the outline of the outer circumference of that object. Similarly, when "internal shape" in a particular configuration (for example, the internal shape of the housing hole 22) is referred to, it refers to the shape of the outline of the inner circumferential surface of that configuration. The internal shape of the first region 23 is the same as the outer shape of the spindle body 31 when viewed from the radial direction. The first region 23 is the region in which the spindle 8 is housed while its radial outward detachment is restricted by the arm portion 32, and is the part to which the spindle 8 is ultimately attached.

[0029] The second region 24 is formed to be larger than the first region 23 when viewed from the radial direction. The second region 24 is in communication with the first region 23. In this embodiment, the second region 24 is formed in a rectangular shape with the axial direction as the long axis when viewed from the radial direction. Furthermore, in this embodiment, a part of the second region 24 (the region near one end in the axial direction) overlaps with the first region 23. The second region 24 is formed to be larger than the overall outer shape of the nut 8, including the nut body 31 and the arm portion 32, when viewed from the radial direction. Therefore, the nut 8 can be inserted from the radial outside to the radial inside of the nut body 7 through the second region 24. In other words, the second region 24 is formed to be the size and shape necessary to insert the nut 8 from the radial outside to the radial inside of the nut body 7 while the outer peripheral surface 44 (see Figure 3) of the nut body 31 is facing radially outward.

[0030] Since the first region 23 and the second region 24 are in communication with each other, a single housing hole 22 is formed in the nut body 7 by the first region 23 and the second region 24. The nut 8 is then housed in this housing hole 22 (the first region 23). More specifically, the nut 8 is housed in the first region 23 with the arm portion 32 aligned circumferentially and the handle portion 33 protruding radially outward (first posture P1). The second region 24 is formed to include the overall outer shape of the nut 8 in the second posture P2, which is different from the first posture P1 when viewed radially. In this embodiment, the second posture P2 is a posture rotated approximately 90° around an axis along the radial direction relative to the first posture P1. In other words, the second posture P2 is a posture in which the arm portion 32 is aligned axially and the handle portion 33 protrudes radially outward. The housing hole 22 is formed so that the longitudinal direction of the first region 23 and the longitudinal direction of the second region 24 are perpendicular to each other. As a result, in the second position P2, the piece 8 is inserted radially into the inside of the nut body 7 through the second region 24, and then, in the first position P1, the arm portion 32 engages with the inner circumferential rolling groove 20, thereby housing it in the first region 23.

[0031] (Method of manufacturing ball screw nuts) Next, a method for manufacturing the nut 3 for the ball screw 1 described above will be explained. Figure 6 is an explanatory diagram showing the nut insertion process ST11 in the manufacturing method of the ball screw nut 3 according to the first embodiment. Figure 7 is an explanatory diagram showing the nut movement process ST12. Figure 8 is an explanatory diagram showing the nut storage process ST13. As shown in Figures 6 to 8, the method for manufacturing a ball screw nut 3 comprises a nut body 7 having a helical inner circumferential rolling groove 20 on which a plurality of rolling elements 4 roll, and a nut 8 having a circulation path 35 that returns the rolling elements 4 from one end 5a to the other end 5b of the inner circumferential rolling groove 20, and comprises a housing hole forming step ST01 and a nut mounting step ST02. First, a cylindrical nut body 7 having a helical inner circumferential rolling groove 20 formed on its inner surface is prepared.

[0032] First, the housing hole formation process ST01 is carried out. In the housing hole formation process ST01, a plurality of housing holes 22 are formed in the nut body 7. In the housing hole formation process ST01, the housing holes 22 are formed to have a first region 23 and a second region 24. At this time, the first region 23 is formed so that the piece 8 can be accommodated with the arm portion 32 of the piece 8 engaged with the inner circumferential rolling groove 20 of the nut body 7. In addition, the second region 24 is formed to communicate with the first region 23 and to have an inner shape that is larger than the outer shape of the piece 8 when viewed radially from the front.

[0033] Next, the nut mounting process ST02 is performed. In the nut mounting process ST02, the nut 8 is placed in the housing hole 22 formed in the housing hole forming process ST01, and the nut 8 is attached to the nut body 7. The nut mounting process ST02 includes a nut insertion process ST11, a nut movement process ST12, and a nut housing process ST13. As shown in Figure 6, the nut insertion process ST11 is performed first. In the nut insertion process ST11, the nut 8 is inserted from the radial outside of the nut body 7 through the second region 24 to the radial inside of the nut body 7. At this time, the nut 8 is inserted while gripping the handle portion 33 of the nut 8 with, for example, a robot arm 19. In the nut insertion process ST11, the nut 8 is inserted in the second posture P2.

[0034] Next, as shown in Figure 7, the nut movement process ST12 is performed. In the nut movement process ST12, at least one of the position and orientation of the nut 8 inserted radially inside the nut body 7 is changed. Specifically, in this embodiment, the nut 8 is rotated 90° around an axis along the radial direction to change from the second orientation P2 to the first orientation P1, and is also moved parallel along the axial direction to a position where the nut 8 overlaps with the first region 23 when viewed from the radial direction.

[0035] Next, as shown in Figure 8, the link sizing process ST13 is performed. In the link sizing process ST13, the link 8 is pulled up radially outward to sizing it into the first region 23 of the sizing hole 22. The link sizing process ST13 is completed when the link body 31 is sizing into the first region 23 and the arm portion 32 engages with a predetermined inner circumference rolling groove 20.

[0036] Through the above steps, a nut 3 is formed in which a nut 8 is attached to the housing hole 22 of the nut body 7. Furthermore, after the nut housing step ST13 is completed, the screw shaft 2 is inserted into the inside of the nut 3 and the rolling elements 4 are filled into the rolling path 5. This forms a ball screw 1 equipped with the aforementioned nut 3. The insertion of the screw shaft 2 into the inside of the nut 3 prevents the nut 8 from falling out radially inward. Furthermore, in order to prevent the piece 8 from falling radially inward between the completion of the piece housing process ST13 and the insertion of the screw shaft 2 into the inside of the nut 3, grease may be applied between the piece 8 and the first region 23 of the housing hole 22 to temporarily fix the piece 8 in place. This prevents the piece 8 from falling out even after the piece housing process ST13 is completed and the robot arm 19 is removed. Alternatively, the gripping state by the robot arm 19 may be maintained until the screw shaft 2 is inserted.

[0037] (Effect, Action) The manufacturing method for the ball screw 1 and ball screw nut 3, and the ball screw socket 8 of this embodiment can provide the following effects. In other words, according to the ball screw 1 of this embodiment, the nut 3 has a nut body 7 and a nut 8 that is attached to the housing hole 22 of the nut body 7. The nut 8 has a nut body 31 having a circulation path 35 and an arm portion 32 that protrudes from the nut body 31. The arm portion 32 protrudes from the nut body 31 and is locked to the nut body 7. The provision of the arm portion 32 prevents the nut 3 from falling out radially to the outside. Therefore, there is no need to separately provide a sleeve or the like to prevent the nut 8 from falling out radially to the outside, and the increase in the number of parts can be suppressed. The housing hole 22 has a first region 23 for housing the link 8, and a second region 24 that communicates with the first region 23 and is formed to be larger than the outer shape of the link 8 when viewed radially from the front. Since the housing hole 22 has the second region 24, the link 8 can be inserted from the radial outside to the inside of the nut body 7 through the second region 24. In this way, the link 8 can be accessed from the radial outside of the nut body 7, which improves the ease of mounting the link 8 having the arm portion 32 compared to the conventional technique in which the link 8 is inserted from the axial end. In particular, even when it is difficult to access the link 8 from the axial direction, such as when the inner diameter of the nut 3 is small or the shaft length of the nut 3 is long, the link 8 can be easily inserted into the inside of the nut body 7 and the link 8 can be mounted. Therefore, it is possible to provide a ball screw 1 that can improve the workability related to the installation of the spool 8 compared to conventional technology, while suppressing an increase in the number of parts.

[0038] The link 8 is housed in the first region 23 in the first position P1, and the second region 24 is formed to include the shape of the link 8's outer form in the second position P2, which is different from the first position P1 when viewed radially. Therefore, the position of the link 8 when passing through the second region 24 (second position P2) and the position of the link 8 when it is finally attached to the nut body 7 (first position P1) are different from each other. This makes it difficult for the link 8 housed in the first region 23 to return to the second region 24, thereby suppressing the link 8 from coming loose during the installation process and ensuring that the link 8 is reliably housed in the first region 23. For example, if the first position P1 and the second position P2 are 90° apart from each other, the slippage of the link 8 can be suppressed even more reliably.

[0039] When viewed from the radial direction of the nut 3, a portion of the second region 24 is formed to overlap with the first region 23. This makes it possible to keep the overall size (total internal area) of the combined housing hole 22 (the second region 24 and the first region 23) smaller compared to the case where the second region 24 and the first region 23 do not overlap when viewed from the radial direction. Therefore, an increase in the diameter of the housing hole 22 can be suppressed, and a decrease in the rigidity of the nut 3 can be suppressed. Furthermore, this can be applied even when the axial distance between multiple housing holes 22 is narrow.

[0040] Since the piece 8 has a handle portion 33, the handle portion 33 can be gripped when installing the piece 8. Therefore, the workability related to installing the piece 8 can be improved.

[0041] The handle portion 33 is formed to protrude radially outward from the main body 31 of the spinning top. This makes it easier to grasp the handle portion 33 by, for example, a robotic arm 19 or the hand of a worker (human). Therefore, the workability related to the installation of the spinning top 8 can be further improved.

[0042] When the socket 8 is attached to the nut body 7, the arm portion 32 is positioned (engaged) in the inner circumferential rolling groove 20 formed in the nut 3. Since the inner circumferential rolling groove 20 can be used as the engagement portion of the arm portion 32, there is no need to separately form an engagement portion for the arm portion 32 on the inner circumferential surface of the nut body 7. Therefore, the work process for attaching the socket 8 can be simplified compared to the case where there is a separate process for forming the engagement portion. Thus, workability can be improved while effectively suppressing the outward radial displacement of the socket 8.

[0043] The manufacturing method for the ball screw nut 3 of this embodiment comprises a housing hole forming step ST01 and a nut mounting step ST02. In the housing hole forming step ST01, a housing hole 22 having a first region 23 and a second region 24 is formed. The nut mounting step ST02 further comprises a nut insertion step ST11 in which a nut 8 is inserted radially inward into the nut 3 via the second region 24, and a nut housing step ST13 in which the nut 8 is housed in the first region 23 by pulling the nut 8 radially outward. The nut 8 attached to the nut body 7 by the nut mounting step ST02 is prevented from falling radially outward by the arm portion 32 being locked to the nut body 7. Therefore, there is no need to separately provide a sleeve or the like to prevent the nut 8 from falling radially outward, and the increase in the number of parts can be suppressed. In the insert mounting process ST02, the insert 8 can be inserted from the radially outer side to the inner side of the nut body 7 through the second region 24. This allows the insert 8 to be accessed from the radially outer side of the nut body 7, improving the ease of mounting the insert 8, which has an arm portion 32, compared to the conventional technique in which the insert 8 is inserted from the axial end. This method is particularly suitable when the inner diameter of the nut 3 is small or the axial length of the nut 3 is long. Therefore, it is possible to provide a method for manufacturing a nut 3 for a ball screw 1 that can improve the workability related to attaching the nut 8 compared to conventional technology, while suppressing an increase in the number of parts.

[0044] In the socket housing process ST13, the socket 8 inserted inside the nut body 7 is moved parallel to the axial direction of the nut 3, and then the socket 8 is pulled up. This allows the socket 8 to be easily housed in the first area 23. Therefore, the workability related to the installation of the socket 8 can be improved.

[0045] In the insert storage process ST13, the orientation of the insert 8, which is inserted inside the nut 3, is changed by 90° before the insert 8 is pulled up. Since the orientation (angle) of the insert 8 when passing through the second region 24 and the orientation (angle) of the insert 8 when it is finally stored in the storage hole 22 are different from each other, it becomes difficult for the insert 8 stored in the first region 23 to return to the second region 24. Therefore, the slippage of the insert 8 during the installation process is suppressed, and the insert 8 can be reliably stored in the first region 23.

[0046] The nut 8 has a handle portion 33, and in the nut mounting process ST02, the robot arm 19 grips the handle portion 33 and attaches the nut 8 to the nut body 7. This ensures that the robot arm 19 can securely grip the nut 8. Therefore, the nut 8 can be easily attached. Furthermore, since the handle portion 33 is provided on the outer circumferential surface 44 of the nut 8 that faces radially outward when the nut 8 is attached to the nut body 7, the handle portion 33 does not interfere with the housing hole 22 (first area 23 and second area 24) in the nut mounting process ST02. Therefore, the handle portion 33 can be provided without reducing work efficiency.

[0047] The ball screw 1 bearing 8 of this embodiment has a bearing body 31, an arm portion 32, and a handle portion 33. The arm portion 32 engages with the inner circumference of the nut body 7, preventing the bearing 8 housed in the housing hole 22 from falling out radially outward. Therefore, there is no need to separately provide a sleeve or the like on the outer circumference of the nut 3, and the number of parts can be reduced. The handle portion 33 is provided on the side of the bearing body 31 opposite to the side on which the arm portion 32 is provided (the outer circumference 44 of the bearing 8). This allows the bearing 8 to be installed while the handle portion 33 is gripped by a robot arm 19 or the like used for the bearing 8 installation work. Therefore, the workability related to the installation of the bearing 8 can be improved. Therefore, it is possible to provide a ball screw 8 for a ball screw 1 that can improve the workability of attaching the 8 compared to conventional technology while suppressing an increase in the number of parts.

[0048] (Second Embodiment) Next, a second embodiment of the present invention will be described. In the description of the second embodiment, components similar to those in the first embodiment described above will be denoted by the same reference numerals and their descriptions will be omitted as appropriate. Note that the specific configurations are not limited to these embodiments and can be modified as appropriate without departing from the spirit of the present invention. Figure 9 is a front view of the housing hole 222 of the nut 3 according to the second embodiment, viewed from the radial outside. In the second embodiment, the shape of the housing hole 222 differs from that of the first embodiment described above. Note that in Figure 9, as in Figure 5, the link 8 is shown with a dashed line for explanatory purposes. Also, in the second embodiment, the shape of the link 8 is the same as that of the link 8 in the first embodiment, so the description of the link 8 will be omitted below.

[0049] As shown in Figure 9, the housing hole 222 has a first region 223 and a second region 224. The first region 223 is formed in the same shape as the first region 23 in the first embodiment. That is, the first region 223 is rectangular in shape when viewed from the radial direction, with the circumferential direction as the long axis, and is formed to the same size as the outer shape of the spinning top body 31 (see Figure 3). The second region 224 is rectangular in shape that is larger than the first region 223 when viewed from the radial direction. Specifically, the second region 224 is formed to the size that includes the outer shape of the entire spinning top 8, including the spinning top body 31 and the arm portion 32. In the second embodiment, the long axis of the second region 224 is inclined by a predetermined angle (e.g., 30°) with respect to the long axis of the first region 223 when viewed from the radial direction. In other words, the second posture P2 in the second embodiment is a posture rotated by approximately 30° around an axis along the radial direction relative to the first posture P1. A part of the second region 224 overlaps with the first region 223.

[0050] When attaching the socket 8 to the nut body 207, first, in the second position P2, the socket 8 is inserted from the radial outside to the inside of the nut body 207 through the second region 224. Then, the socket 8 is rotated by a predetermined angle (30° in this embodiment) and translated parallel to the axial direction until the socket 8 overlaps with the first region 223 when viewed from the radial direction. Finally, in the first position P1, the socket 8 is pulled up radially outward, thereby housing the socket 8 in the first region 223 of the housing hole 222.

[0051] The ball screw 1 of the second embodiment can achieve the same effects as the first embodiment described above. Specifically, because the nut 8 has an arm portion 32, the nut 8 is prevented from falling out radially to the outside. Therefore, there is no need to separately provide a sleeve or the like to prevent the nut 8 from falling out radially to the outside, and the number of parts can be reduced. In addition, since the nut 8 can be accessed from the radial outside of the nut body 207 through the second region 224 of the housing hole 222, the ease of installation of the nut 8 having an arm portion 32 can be improved compared to the conventional technique in which the nut 8 is inserted from the axial end. In the second embodiment described above, the long axis direction of the second region 224 was configured to be inclined at 30° with respect to the long axis direction of the first region 223, but the inclination angle is not limited to 30°. The long axis direction of the second region 224 may be formed to be inclined at a desired angle within the range of 0° to 90° with respect to the long axis direction of the first region 223. This improves the degree of freedom in the shape of the receiving hole 222 and increases the versatility of the nut 3.

[0052] (Third embodiment) Next, a third embodiment of the present invention will be described. In the description of the third embodiment, components similar to those in the first embodiment described above will be denoted by the same reference numerals and their descriptions will be omitted as appropriate. Figure 10 is a front view of the housing hole 322 of the nut 3 according to the third embodiment, viewed from the radially outer side. In the third embodiment, the shape of the housing hole 322 differs from that of the first and second embodiments described above. In the third embodiment as well, the shape of the nut 8 is the same as that of the nut 8 in the first embodiment.

[0053] As shown in Figure 10, the housing hole 322 has a first region 323 and a second region 324. The first region 323, like the first region 23 in the first embodiment, is rectangular in shape when viewed radially, with the circumferential direction as the long axis, and is formed to be the same size as the outer shape of the spinning top body 31. The second region 324 is formed to be the same size as the outer shape of the spinning top 8 in the same posture (first posture P1) as the spinning top 8 housed in the first region 323, when viewed radially. Specifically, the second region 324 has a rectangular portion corresponding to the outer shape of the spinning top body 31 when viewed radially, and a semicircular protruding portion corresponding to the outer shape of the arm portion 32.

[0054] When attaching the socket 8 to the nut body 307, first, in the first position P1, the socket 8 is inserted from the radial outside to the inside of the nut body 307 through the second region 324. Then, the socket 8 is moved parallel along the axial direction until it overlaps with the first region 323 when viewed from the radial direction. Finally, by pulling the socket 8 outward in the radial direction, the socket 8 is accommodated in the first region 323 of the housing hole 322.

[0055] According to the third embodiment of the ball screw 1, the second region 324 is formed to a size that includes the outer shape of the ball screw 8 in the same position (first position P1) as the ball screw 8 housed in the first region 323. As a result, after the ball screw 8 is inserted into the inside of the nut body 307 through the second region 324, the ball screw 8 can be housed in the first region 323 simply by translating it without rotating it. In other words, the step of rotating the ball screw 8 inside the nut body 307 can be omitted. Therefore, the work process related to installing the ball screw 8 can be simplified and workability can be improved.

[0056] It should be noted that the technical scope of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the first embodiment described above, a configuration in which two links 8 are provided for one nut 3 was explained, but the number of links 8 is not limited to the number in the embodiment. Furthermore, in a nut 3 having multiple links 8, the configuration of this embodiment may be adopted for some of the links 8. For example, when applied to a nut 3 with a long shaft length, the receiving hole 22 located in the axial center (i.e., a location that is difficult to access from the axial direction) among the multiple receiving holes 22 may be formed to have the first region 23 and the second region 24 described above. That is, the links 8 to be received in the receiving hole 22 located in the axial center may be inserted into the inside of the nut body 7 from the radial outside of the nut body 7 through the second region 24. In this case, the other links located near the axial end may be inserted into the inside of the nut body 7 from the end of the nut body 7 along the axial direction, as in the conventional method. By adopting the configuration of this embodiment for only some of the links 8 among the multiple links 8 in this way, the amount of processing on the nut body 7 can be minimized, and the links 8 can be easily placed even in receiving holes 22 located in places that are difficult for the robot arm 19 to access.

[0057] The shape of the handle portion 33 is not limited to the shape of the embodiment. For example, the handle portion 33 may be a recess or notch instead of a convex portion. The handle portion 33 may be formed into various shapes that the robot arm 19 can grasp. The robot arm 19 may grasp the spool 8 by means of suction, for example. In this case, the handle portion 33 may be a surface that has been surface-treated on the outer circumferential surface 44 of the spool body 31.

[0058] The arm portion 32 may be locked to the nut body 7 by engaging with a groove other than the inner circumferential rolling groove 20. A separate groove for engaging the arm portion 32 may be provided. Alternatively, the arm portion 32 may be locked so as to extend along the axial direction of the nut 3. In this case, a recess or hole for engagement with the arm portion 32 may be separately formed on the inner circumferential surface of the nut body 7. However, the configuration of this embodiment in which the arm portion 32 engages with the inner circumferential rolling groove 20 has the advantage of reducing the number of processing steps by engaging the arm portion 32 with the already formed inner circumferential rolling groove 20.

[0059] In the embodiments described above, a ball screw 1 in which the nut 3 rotates and the screw shaft 2 moves in a direction along the central axis C has been described, but the invention is not limited thereto. The configurations of the embodiments described above may also be applied to a ball screw in which the screw shaft 2 rotates and the nut 3 moves in a direction along the central axis C.

[0060] Furthermore, this disclosure may also be a combination of the following configurations. (1) A screw shaft having spiral outer rolling grooves on its outer surface, A nut having a spiral inner circumferential rolling groove on its inner surface, A plurality of rolling elements are 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, Equipped with, The aforementioned nut is The nut body and The nut body has a slot that is attached to a housing hole formed therein and forms a circulation path that returns the rolling element from one end to the other end of the rolling path, The aforementioned frame is, The spinning top body having the aforementioned circulation path, It has an arm portion that protrudes from the main body of the slot and is locked to the nut body, thereby preventing it from falling out radially outward from the housing hole, The aforementioned housing hole is A first region that houses the spool in a state where the spool's radial outward detachment is restricted by the arm portion, A second region is formed to communicate with the first region and to be larger than the outer shape of the nut in a front view when viewed from the radial direction of the nut, Having, Ball screw. (2) The aforementioned frame is housed in the first region in the first position, The second region is formed to a size that includes the shape of the outer form of the top in a second posture that is different from the first posture when viewed from the radial direction. (1) The ball screw described above. (3) The second region is formed to a size that includes the shape of the outer form of the spinning top in the same orientation as the spinning top housed in the first region. (1) The ball screw described above. (4) When viewed from the radial direction of the nut, a part of the second region overlaps with the first region. (2) or (3) the ball screw described above. (5) The aforementioned socket has a handle portion on the radially outward-facing surface when the socket is attached to the nut body. (1) The ball screw described above. (6) The handle portion is formed to protrude radially outward from the main body of the spinning top. (5) The ball screw described above. (7) In the state in which the socket is attached to the nut body, the arm portion extends along the circumferential direction of the nut and is positioned in the inner circumferential rolling groove formed in the nut. (1) The ball screw described above. (8) A method for manufacturing a ball screw nut comprising a nut body having a spiral inner circumferential rolling groove on which multiple rolling elements roll, and a nut having a circulation path that returns the rolling elements from one end to the other of the inner circumferential rolling groove, A process of forming a housing hole in the nut body, A frame mounting step in which the frame is fitted into the aforementioned housing hole, Equipped with, In the above-mentioned housing hole forming step, a housing hole is formed having a first region in which the piece is housed with the arm portion of the piece locked to the nut body, and a second region that communicates with the first region and is formed to be larger than the outer shape of the piece in a front view when viewed from the radial direction of the nut. The aforementioned frame mounting process is, A inserting step of inserting the insert from the radially outer side of the nut through the second region into the radially inner side of the nut, A component housing step involves changing at least one of the position and orientation of the component inserted inside the nut, thereby pulling the component outward in the radial direction, and housing the component in the first region. Having, A method for manufacturing ball screw nuts. (9) In the aforementioned slotting step, the slot inserted inside the nut is moved parallel to the axial direction of the nut, and then the slot is pulled up. (8) A method for manufacturing a ball screw nut as described above. (10) In the aforementioned slotting step, the orientation of the slot inserted inside the nut is changed by 90° before the slot is pulled up. (8) A method for manufacturing a ball screw nut as described above. (11) The aforementioned socket has a handle portion on the radially outward-facing surface when the socket is attached to the nut body. In the aforementioned component attachment process, the robot arm grips the handle portion and attaches the component to the nut body. (8) A method for manufacturing a ball screw nut as described above. (12) A ball screw insert that is attached to a nut having a spiral inner circumferential rolling groove on its inner surface, and has a circulation path that returns the rolling element from one end to the other end of the inner circumferential rolling groove, A nut body having the aforementioned circulation path and being housed in a housing hole formed in the nut body, An arm portion that protrudes from the main body of the slot and is locked to the nut body, thereby preventing it from falling out radially outward from the housing hole, A handle portion is provided on the side of the top body opposite to the side on which the arm portion is provided, and the robot arm can grip the top when attaching the top to the nut body. Having, A socket for ball screws. [Explanation of Symbols]

[0061] 1 Ball screw 2 Screw shaft 3 nuts 4 Rolling elements 5. Turning track 6. Outer circumference rolling grooves 7 Nut body 8 frames 19 Robot Arm 20 Inner Circumferential Rolling Grooves 22 Intake holes 23 First area 24 Second area 31 Frame Body 32 Arm section 33 Handle section 35 Circulation route P1 First posture P2 Second posture ST01 Hole Formation Process ST02 Frame Installation Process ST11 Insertion Process ST13 Frame storage process

Claims

1. A screw shaft having spiral outer rolling grooves on its outer surface, A nut having a spiral inner circumferential rolling groove on its inner surface, A plurality of rolling elements are 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, Equipped with, The aforementioned nut is The nut body and The nut body has a slot that is attached to a housing hole formed therein and forms a circulation path that returns the rolling element from one end to the other end of the rolling path, The aforementioned frame is, The spinning top body having the aforementioned circulation path, It has an arm portion that protrudes from the main body of the slot and is locked to the nut body, thereby preventing it from falling out radially outward from the housing hole, The aforementioned housing hole is A first region that houses the spool in a state where the spool's radial outward detachment is restricted by the arm portion, A second region is formed to communicate with the first region and to be larger than the outer shape of the nut in a front view when viewed from the radial direction of the nut, Having, Ball screw.

2. The aforementioned frame is housed in the first region in the first position, The second region is formed to a size that includes the shape of the outer form of the top in a second posture that is different from the first posture when viewed from the radial direction. The ball screw according to claim 1.

3. The second region is formed to a size that includes the shape of the outer form of the spinning top in the same orientation as the spinning top housed in the first region. The ball screw according to claim 1.

4. When viewed from the radial direction of the nut, a part of the second region overlaps with the first region. The ball screw according to claim 2 or claim 3.

5. The aforementioned socket has a handle portion on the radially outward-facing surface when the socket is attached to the nut body. The ball screw according to claim 1.

6. The handle portion is formed to protrude radially outward from the main body of the spinning top. The ball screw according to claim 5.

7. In the state in which the socket is attached to the nut body, the arm portion extends along the circumferential direction of the nut and is positioned in the inner circumferential rolling groove formed in the nut. The ball screw according to claim 1.

8. A method for manufacturing a ball screw nut comprising a nut body having a spiral inner circumferential rolling groove on which multiple rolling elements roll, and a nut having a circulation path that returns the rolling elements from one end to the other of the inner circumferential rolling groove, A process of forming a housing hole in the nut body, A frame mounting step in which the frame is fitted into the aforementioned housing hole, Equipped with, In the above-mentioned housing hole forming step, a housing hole is formed having a first region in which the piece is housed with the arm portion of the piece locked to the nut body, and a second region that communicates with the first region and is formed to be larger than the outer shape of the piece in a front view when viewed from the radial direction of the nut. The aforementioned frame mounting process is, A inserting step of inserting the insert from the radially outer side of the nut through the second region into the radially inner side of the nut, A component housing step involves changing at least one of the position and orientation of the component inserted inside the nut, thereby pulling the component outward in the radial direction, and housing the component in the first region. Having, A method for manufacturing ball screw nuts.

9. In the aforementioned slotting step, the slot inserted inside the nut is moved parallel to the axial direction of the nut, and then the slot is pulled up. A method for manufacturing a ball screw nut according to claim 8.

10. In the aforementioned slot installation step, the orientation of the slot inserted inside the nut is changed by 90° before the slot is pulled up. A method for manufacturing a ball screw nut according to claim 8.

11. The aforementioned socket has a handle portion on the radially outward-facing surface when the socket is attached to the nut body. In the aforementioned component attachment process, the robot arm grips the handle portion and attaches the component to the nut body. A method for manufacturing a ball screw nut according to claim 8.

12. A ball screw insert that is attached to a nut having a spiral inner circumferential rolling groove on its inner surface, and has a circulation path that returns the rolling element from one end to the other end of the inner circumferential rolling groove, A nut body having the aforementioned circulation path and being housed in a housing hole formed in the nut body, An arm portion that protrudes from the main body of the slot and is locked to the nut body, thereby preventing it from falling out radially outward from the housing hole, A handle portion is provided on the side of the top body opposite to the side on which the arm portion is provided, and the robot arm can grip the top when attaching the top to the nut body. Having, A socket for ball screws.

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