BALL DRIVE

Abstract

A ball screw drive of the present disclosure comprises a nut, a threaded spindle, several balls, and one or more components. At least one or more recesses are provided on the outer circumferential surface of the threaded spindle. The recesses are offset radially inward and receive the components. A recess has a first, radially outwardly directed bottom surface. At least a portion of the first bottom surface is flat. A component comprises a second bottom surface, a circumferential groove surface, a bottom opening, a pair of component-side openings, and a pair of tongues. The second bottom surface abuts the first bottom surface. The circumferential groove surface extends radially outward from the second bottom surface. The interior of the circumferential groove surface forms a orbit. The bottom opening opens the orbit toward the radially inner side. The pair of component-side openings opens the orbit at its circumference and connects the orbit to the track.The pair of tongues guides a ball that has entered the orbit from the track to the radially inner side. A section of the first base surface, which closes the base opening, acts as a rolling surface for the ball as it moves along the orbit.

Description

Area

[0001] The present disclosure relates to a ball screw drive. background

[0002] A ball screw drive comprises a nut, a threaded spindle, several balls, and a recirculating component. The threaded spindle passes through the nut. The several balls are arranged between the nut and the threaded spindle. An inner circumferential track is formed on the inner surface of the nut. An outer circumferential track, opposite the inner circumferential track, is formed on the outer circumferential surface of the threaded spindle. A helical track is formed between the inner and outer circumferential track surfaces. The several balls are arranged in this track and move helically along it. The recirculating component returns a ball, which has moved from one end of the track to the other, to one end of the track. Examples of the recirculating component include a piece that returns a ball a certain distance.

[0003] In a ball screw drive described in the following patent literature, a recess is formed. This recess is radially inward-facing on the outer circumferential surface of the threaded spindle. A component, attached to the threaded spindle, is inserted into this recess. This component also has an outer diameter surface and a circumferential groove surface. The outer diameter surface faces radially outward. The circumferential groove surface is offset radially inward from the outer diameter surface. Viewed from its radially outer side, the circumferential groove surface has an S-shape. A ball moves radially inward within the circumferential groove surface of the component and runs over the thread of the nut. Citation list for patent literature

[0004] Patent specification 1: JP 2004-225770 A Summary: Technical Task

[0005] According to the aforementioned patent literature, if the ball moves radially inwards, it can become jammed between the circumferential groove surface and the inner circumferential surface of the nut. Therefore, smooth rolling of the ball is not guaranteed. Furthermore, if the ball is jammed, a groove shoulder of the circumferential groove surface can be damaged.

[0006] The present disclosure was made in consideration of the above, and one of its aims is to provide a ball screw drive that allows a ball to roll smoothly and prevents damage to a part. Solution to the task

[0007] A ball screw drive according to an embodiment of the present disclosure comprises a nut with an inner circumferential track surface on an inner circumferential surface; a threaded spindle penetrating the nut and having an outer circumferential track surface on an outer circumferential surface; several balls arranged on a track between the outer circumferential track surface and the inner circumferential track surface; and at least one or more pieces that allow the balls to rotate, wherein at least one or more recesses, radially inwardly recessed and receiving the pieces, are provided on the outer circumferential surface of the threaded spindle, each of the recesses having a first bottom surface that projects radially outward, at least a portion of the first bottom surface being flat, each of the pieces comprising: a second bottom surface that abuts the first bottom surface;a grooved surface that extends radially outward from the second bottom surface and has an interior space forming an orbit; a bottom opening that opens the orbit radially inward; a pair of piece-side openings that open the orbit at its circumference and connect the orbit to the track; and a pair of tongues that guide the balls that have entered the orbit from the track radially inward; and a section that closes the bottom opening of the first bottom surface, is a rolling surface for the balls moving on the orbit.

[0008] According to a ball screw drive of the present disclosure, a ball is guided radially inwards by a tongue. This prevents the ball from being jammed between a circumferential groove surface and an inner circumferential track surface. That is, the ball rolls smoothly, and damage to a groove shoulder of the circumferential groove surface is avoided. Furthermore, the depth of a recess can be measured by using a flat surface of a first bottom surface of the recess as a reference surface. The dimensioning of the recess is easy to handle. Additionally, the orbit of a component is opened radially inwards. That is, if the component is manufactured using a mold, the mold can be moved (released) radially inwards to form the orbit (circulating groove surface). Therefore, the component is easier to manufacture than in a case where the radially inner side of the orbit is closed.

[0009] In a preferred aspect of the ball screw drive described above, the first bottom surface is completely flat.

[0010] According to this embodiment, the first base surface is completely flat, allowing it to be easily shaped. Furthermore, the orbit has a linear shape in the axial direction, and the ball rolls without friction. When the ball enters the orbit from the track, its path changes radially inward along an extension of the track. That is, the ball's path curves radially inward from the track. If the first base surface is recessed, the ball's path has a large bending angle. In contrast, according to the present disclosure, the first base surface is flat, resulting in a small bending angle for the ball's path. Therefore, the ball moves (rolls) without friction between the outer circumferential track surface and the orbit.

[0011] Furthermore, in a preferred aspect of the ball screw drive described above, viewed from an axial direction parallel to the threaded spindle, the first bottom surface extends in a cutting direction that intersects a virtual line extending radially outward from a center of the threaded spindle, a recessed surface that is recessed radially inward is provided in a central section of the first bottom surface in the cutting direction, and flat surfaces are provided on both sides of the recessed surface in the cutting direction.

[0012] One end of the first base surface in the cutting direction is flat, and the ball's path has a small bending angle. Therefore, this configuration also causes the ball to move (roll) smoothly between the outer circumferential track surface and the orbit. Furthermore, a recessed area is provided in a central region of the first base surface in the cutting direction. Thus, both ends (flat surfaces) of the first base surface in the cutting direction are located on the radially outer side, compared to a completely flat first base surface. As a result, the area cut out by the recess on the outer circumferential track surface is reduced, and the load-bearing capacity of the ball screw drive is improved.

[0013] In a preferred embodiment of the ball screw drive described above, each of the tongues has a radially outwardly projecting rib.

[0014] According to its design, a rib improves the strength of a tongue.

[0015] In a preferred aspect of the ball screw drive described above, the recess further comprises an annular inner circumferential surface that surrounds the piece. The inner circumferential surface has a pair of side faces that enclose the piece from both sides in the cutting direction that intersects a virtual line extending radially outward from the center of the threaded spindle.

[0016] According to the configuration, the piece is enclosed between a pair of side surfaces. This prevents the piece from moving in the cutting direction and falling out of the recess.

[0017] Furthermore, in a preferred aspect of the ball screw drive described above, a distance from the center of the threaded spindle to a thread of the nut is defined as R, a diameter of each of the balls is defined as Dw, a distance between a section of an outer diameter surface of each of the pieces facing the thread of the nut and the thread of the nut is 0.2 mm or more and 1.5 mm or less, a thickness from the section of the outer diameter surface of each of the pieces facing the thread of the nut to the orbital groove surface is 0.3 mm or more and 1.0 mm or less, a radial gap of the orbit is 0.05 × Dw or more and 0.25 × Dw or less, and a distance h between the first bottom surface and the center of the threaded spindle satisfies the following expression (1). R / 2−1.25×Dw−2.5(mm) <h<R / 2−1,05×Dw−0,5(mm)

[0018] According to the configuration, the first base surface is arranged radially outwards. This lengthens the raceway and improves the load-bearing capacity of the ball screw drive.

[0019] Furthermore, in a preferred aspect of the ball screw drive described above, viewed from an axial direction parallel to the threaded spindle, the first bottom surface extends in a cutting direction that intersects a virtual line extending radially outward from a center of the threaded spindle, each of the recesses having at least one opening open in the cutting direction, and each of the recesses being able to move along the first bottom surface in the cutting direction. Alternatively, in a preferred aspect of the ball screw drive described above, each of the recesses has two openings, and the two openings comprise: one opening open to one side in the cutting direction; and one opening open to the other side in the cutting direction.

[0020] Depending on the configuration, the piece can be fastened from the cutting direction of the recess. Additionally, the piece can also be fastened from the radially outer side of the recess. This provides more options regarding the direction in which the piece is fastened and improves the fastening options.

[0021] In a preferred aspect of the ball screw drive described above, each of the recesses has a pair of axially facing surfaces, each of the pieces has a pair of side surfaces that are axially facing and facing the pair of facing surfaces, a groove that is axially recessed and extends in the cutting direction is formed on at least one of the pair of facing surfaces, and a projection that projects axially and is accommodated in the groove is formed on at least one of the pair of side surfaces. Alternatively, in a preferred aspect of the ball screw drive described above, the groove is formed on both of the mutually facing surfaces of the pair, and the projection is formed on both of the pair of side surfaces.

[0022] According to the configuration, when a load acts on the piece in the direction of the radially outer side, a projection is caught in a groove. This restricts the movement of the piece in the radially outer direction.

[0023] In a preferred aspect of the ball screw drive described above, each of the recesses has a pair of mutually facing surfaces that point in an axial direction, and each of the pieces has a fastening allowance with respect to the pair of mutually facing surfaces and is enclosed between the pair of mutually facing surfaces.

[0024] Due to its design, the piece can only move with difficulty towards the radially outer side and in the cutting direction. This limits the piece's ability to fall out of the recess.

[0025] Furthermore, in a preferred aspect of the ball screw drive described above, a direction orthogonal to both the axial direction and the cutting direction is defined as an orthogonal direction, a direction in which a center of the threaded spindle is arranged as seen from the first bottom surface, is defined as a first orthogonal direction, and a compression section projecting more than the first bottom surface in the first orthogonal direction is formed at at least one of the two ends of each of the pieces in the cutting direction.

[0026] According to the design, the projection on the outer circumferential surface of the threaded spindle is trapped when a load acts on the workpiece in the cutting direction. This restricts the movement of the workpiece in the cutting direction.

[0027] Furthermore, in a preferred aspect of the ball screw drive described above, a direction orthogonal to both the axial direction and the cutting direction is defined as an orthogonal direction, a direction opposite to a direction in which a center of the threaded spindle is arranged as seen from the first bottom surface, is defined as a second orthogonal direction, and a compression section arranged on at least one of the two sides of each of the pieces in the cutting direction and projecting further in the second orthogonal direction than the first bottom surface is formed on the threaded spindle.

[0028] According to the design, when a load acts on the piece in the cutting direction, a section of the piece is compressed and trapped in the cutting direction. This restricts the movement of the piece in the cutting direction.

[0029] Furthermore, in a preferred aspect of the ball screw drive described above, one or more holes are formed on the first bottom surface, and a projection intended to enter each of the holes is formed on the second bottom surface.

[0030] According to the configuration, the projection is clamped in a hole when a load acts on the workpiece in the cutting direction. This restricts the movement of the workpiece towards the radially outer side. Advantageous effects of the invention

[0031] The ball screw drive of the present disclosure ensures the smooth rolling of a ball. Furthermore, damage to a groove shoulder of a circumferential groove surface is prevented. Brief description of the drawings Fig. Figure 1 is a cross-sectional view of a brake caliper of a first embodiment. Fig. Figure 2 is a perspective view of a piece and a recess of a ball screw drive of the first embodiment. Fig. Figure 3 is a perspective view of the recess of the first embodiment. Fig. Figure 4 is an enlarged view of the recess and the piece of the first embodiment as seen from a radially outer side. Fig. Figure 5 is a schematic cross-sectional view of the piece and a threaded spindle of the first embodiment, taken along a circular path, and is a cross-sectional view taken along line VV in the Fig. 4 was recorded to show details. Fig. Figure 6 is a schematic cross-sectional view of the piece and the threaded spindle of the first embodiment, taken along the axial direction, and, for details, a cross-sectional view taken along line VI-VI in Fig. 4 is recorded. Fig. Figure 7 is a top view of the piece of the first embodiment as seen from the second bottom surface. Fig. Figure 8 is a schematic view of a cross-section of the ball screw drive of a comparative example of the first embodiment, taken along a track and the orbit. Fig. Figure 9 is a top view of a recess of a ball screw drive of a second embodiment seen in the radial direction. Fig. Figure 10 is a cross-sectional view of the ball screw drive of the second embodiment, taken along a track and a orbit. Fig. Figure 11 is a cross-sectional view of a piece and recess of a ball screw drive of a third embodiment, taken along the axial and radial direction. Fig. Figure 12 is a cross-sectional view of a piece and a recess of a ball screw drive of a fourth embodiment along the axial and radial direction. Fig. Figure 13 is a perspective view of a recess and a piece of a fifth embodiment. Fig. Figure 14 is a perspective view of a recess of a threaded spindle of the fifth embodiment. Fig. Figure 15 shows the recess of the fifth embodiment as seen from a sectioning direction. Fig. Figure 16 is a cross-sectional view along line XVI-XVI in the Fig. 15. Fig. Figure 17 shows the piece of the fifth embodiment as seen from the second floor surface. Fig. Figure 18 is a cross-sectional view of the recess and the piece of the fifth embodiment, taken along a direction orthogonal to the axial direction, and, for details, is a cross-sectional view of the recess and the piece taken along line XVIII-XVIII in Fig. 15 is recorded. Fig. Figure 19 shows the depression and the piece of variant 1 seen from the cutting direction. Fig. Figure 20 is a perspective view of the recess of the threaded spindle of variant 1. Fig. Figure 21 shows the depression and the piece of variant 2 seen from the cutting direction. Fig. Figure 22 shows the depression and the piece of variant 3 seen from the cutting direction. Fig. Figure 23 is a cross-sectional view of the depression and the piece of a variant 4 in a direction orthogonal to the axial direction. Fig. Figure 24 shows the section of variant 5 as seen from the second floor surface. Fig. Figure 25 is a cross-sectional view of the ball screw drive of variant 5, which is taken in a direction perpendicular to the axial direction. Fig. Figure 26 is a perspective view of the deepening of variant 6. Fig. Figure 27 shows the section of variant 6 as seen from the second floor surface. Fig. 28 is a cross-sectional view along line XXVIII-XXVIII in the Fig. 26. Description of the embodiments

[0032] The present disclosure is described in detail below with reference to the drawings. It should be noted that the present disclosure is not limited to embodiments for carrying out the following invention (hereinafter referred to as embodiments). Furthermore, the components in the following embodiments include those that are readily conceivable to a person skilled in the art, those that are essentially the same, and those located in so-called similar areas. In addition, the components disclosed in the following embodiments can be suitably combined with one another. (First embodiment)

[0033] Fig. Figure 1 is a cross-sectional view of a brake caliper of a first embodiment. As shown in the Fig. Figure 1 shows a brake caliper 100, a device for preventing the rotation of a wheel (not shown) by clamping a brake disc 101, which rotates with the wheel, between two brake pads 102 and 103. The brake caliper 100 comprises the brake disc 101, the two brake pads 102 and 103, an electric actuator 104, and a housing 120. The electric actuator 104 actuates the brake pad 102.

[0034] The electric actuator 104 comprises a motor 110 and a ball screw drive 1. The motor 110 generates a rotational motion. The ball screw drive 1 converts the rotational motion into a linear motion. A direction parallel to the center O1 of a threaded spindle 2 of the ball screw drive 1 is referred to below as the axial direction. Furthermore, a direction in which the brake disc 101 is arranged as seen from the ball screw drive 1 is referred to as the first direction X1. A direction opposite to the first direction X1 is referred to as the second direction X2.

[0035] The motor 110 comprises a stator 111, a rotor 112, and an output shaft 113. The stator 111 is attached to the inner circumferential surface of the housing 120. The rotor 112 is arranged on the inner circumferential side of the stator 111. The output shaft 113 is rotatably mounted in the housing 120. The stator 111, the rotor 112, and the output shaft 113 are arranged concentrically around the center O1. The output shaft 113 is attached to the inner circumferential side of the rotor 112. The stator 111 is energized to generate a rotating magnetic field. The rotor 112 and the output shaft 113 rotate about the central axis O. A recess 114 is also formed on one end face of the output shaft 113 in the first direction X1. The threaded spindle 2 is fitted into the recess 114.

[0036] The ball screw drive 1 comprises the threaded spindle 2, a nut 6, a ball 4 (in the Fig. 1 not shown, see Fig. 5) and several pieces 5.

[0037] The threaded spindle 2 comprises a coupling section 10 and a threaded spindle body 11. The coupling section 10 is rotatably mounted in a bearing 117. The threaded spindle body 11 is arranged in the first direction X1 with respect to the coupling section 10. One end 10a of the coupling section 10 in the second direction X2 is fitted into the recess 114. Furthermore, the coupling section 10 and the output shaft 113 are coupled such that they cannot rotate relative to each other. Therefore, when the output shaft 113 rotates, the threaded spindle 2 also rotates. An outer circumferential surface 13 and several recesses 14 are provided on the outer circumferential surface of the threaded spindle body 11. The outer circumferential surface 13 extends in a helical fashion. The recesses 14 are offset radially inwards.

[0038] The nut 6 has a cylindrical shape. A cover 7 is also provided on the nut 6, which closes an opening in the nut 6 in the first direction X1. An inner circumferential surface 6a is provided on the inner circumferential surface of the nut 6, facing the outer circumferential surface 13. A spiral track 8 is formed between the outer circumferential surface 13 and the inner circumferential surface 6a. Several balls 4 are arranged on the track 8.

[0039] The outer circumferential surface of the nut 6 rests against a support surface 121 of the housing 120. The outer circumferential surface of the nut 6 and the support surface 121 have a circular shape around the center O1. A small gap exists between the outer circumferential surface of the nut 6 and the support surface 121. This allows the nut 6 to slide axially with respect to the support surface 121. A swivel stop element (not shown) is provided on the outer circumferential surface of the nut 6, which restricts the rotation of the nut 6 around the center O1.

[0040] The cover 7 closes the opening of the nut 6 in the first direction X1. In addition, a surface 7a of the cover 7 facing the first direction X1 is in contact with the brake pad 102.

[0041] When the nut 6 is moved in the first direction X1 by turning the threaded spindle 2, the brake pad 102 moves in the first direction X1. The brake pad 102 presses against the brake disc 101 in the first direction X1, and the brake disc 101 comes into contact with the brake pad 103. This clamps the brake disc 101 between the brake pads 102 and 103 and restricts the rotation of the wheel (not shown).

[0042] The pieces 5 are recirculating devices that guide the ball 4, which is moved along a track 8, back along the track 8 by one track. One piece 5 is also attached to a recess 14. It should be noted that the present disclosure does not specifically address a method for attaching the piece 5 to the recess 14. That is, the piece 5 can be attached to the recess 14, or it is not necessary to attach it to the recess 14. Therefore, in the present disclosure, the piece 5 can be loosely inserted into the recess 14. Alternatively, the piece 5 can be provided with a fastening allowance and fitted into the recess 14. Alternatively, the piece 5 can also be glued to the recess 14. Furthermore, the piece 5 can be attached to the recess 14 by upsetting. As described above, it is not of particular importance whether the piece 5 is attached or not.

[0043] Furthermore, although not specifically shown, the multiple pieces 5 (multiple recesses 14) are arranged in different directions from the center O1 when viewed axially. This ensures that a load acting from the nut 6 via the ball 4 onto the threaded spindle 2 is distributed evenly around the circumference. It should be noted that the multiple pieces 5 are preferably arranged at equal intervals around the circumference.

[0044] The Fig. Figure 2 is a perspective view of a section and recess of the ball screw drive of the first embodiment. As shown in the Fig. As shown in Figure 2, piece 5 is a piece that has an orbit 30 inside. Although examples of a material for forming piece 5 include metals and resins, the present disclosure is not particularly limited to these. Piece 5 comprises the orbit 30, a pair of piece-side openings 31 (in the Fig. Figure 2 shows only a piece-side opening 31) and a pair of tongues 40 and 40. The piece-side openings 31 connect the orbit 30 with the track 8 (outer circumferential track surface 13). Details of the recess 14 and the piece 5 are described below.

[0045] The Fig. Figure 3 is a perspective view of the recess of the first embodiment. As in the Fig. As shown in Figure 3, the recess 14 is formed by cutting out a portion of the outer circumferential surface 13 of the threaded spindle 2 from the radially outer side. The recess 14 has an inner circumferential surface 15 and a first bottom surface 16. The inner circumferential surface 15 surrounds the piece 5. The first bottom surface 16 is directed radially outwards. In the following description, as shown in the Fig. Figure 5 shows a virtual line that runs perpendicular to the first floor surface 16 and orthogonal to the center O1, designated as virtual line K1.

[0046] The Fig. Figure 4 is an enlarged view of the recess and the piece of the first embodiment as seen from the radial outside. Note that a virtual line Z in the Fig. 4 runs through a central section in a groove width of the outer circumferential surface 13 and extends spirally. A direction parallel to the virtual line Z is referred to below as the spiral direction. In addition, a virtual line W runs in the Fig. 4 through a central section in a groove width of the orbit 30. A path along the orbit 30 can in the following be referred to as a longitudinal direction of the orbit 30.

[0047] As in the Fig. As shown in Figure 4, the recess 14 has a rectangular (square) shape when viewed from its radially outer side. Although the recess 14 of the embodiment has a rectangular (square) shape when viewed from its radially outer side, an oval shape for the recess 14 can also be provided within the scope of this disclosure. The present disclosure is not limited to the example of the embodiment. The inner circumferential surface 15 of the recess 14 has a pair of first end faces 17 and 17 and a pair of second end faces 18 and 18. The first end faces 17 and 17 face each other axially. The second faces 18 and 18 are oriented towards each other in a section direction Y. It should be noted that, as shown in Figure 4, the recess 14 has a rectangular (square) shape when viewed from its radially outer side. Fig. 5 shows that the cutting direction Y intersects the virtual line K1 (is orthogonal to it), which extends from the center O1 (in Fig. 5 (not shown) extends radially outwards in the axial direction.

[0048] A first end face 17 is formed by cutting out part of a thread 13a of the outer circumferential surface of the raceway 13. Therefore, a thin section 19 with a small thickness (thickness in the direction orthogonal to the helix direction) H1 is provided in part of the thread 13a.

[0049] The first end face 17 extends spirally. That is, the thin section 19 has a uniform thickness H1 in its entire direction (spiral direction). Therefore, the thin section 19 of the embodiment does not have a section with relatively low strength. Deformation of the thread 13a (thin section 19) is prevented. It should be noted that in the present disclosure, the first end face 17 can extend in the cutting direction Y, and the present disclosure is not limited to the example in the embodiment.

[0050] A second end face 18 extends axially, viewed from the radially outer side. As in the Fig. As shown in Figure 3, part of the second end face 18 is cut out by the outer circumferential surface 13. This means that an opening 13b on the thread spindle side is provided on the second end face 18. Therefore, the second end face 18 has an end face 13c of the thread 13a and partial end faces 13d of the thread 13a. The end face 13c is located in a central section of the second end face 18 in the axial direction. The partial end faces 13d are located at both ends of the second end face 18 in the axial direction.

[0051] It should be noted that the end face 13c of the thread 13a has the same cross-sectional shape as the thread 13a. Viewed from the cutting direction Y, the dividing end faces 13d of the thread 13a have the same shape as one of those obtained by axially dividing the end face 13c of the thread 13a into two. As shown in the Fig. As shown in Figure 4, the partial end surfaces 13d of the thread 13a, viewed from the radially outer side, have the shape of an arc (R).

[0052] As in the Fig. As shown in Figure 4, the pair of second end faces 18 is a pair of side faces that enclose the piece 5 from both sides in the cutting direction Y.

[0053] As in the Fig. As shown in Figure 3, a portion of the first base surface 16 has no recessed area or similar feature. That is, the first base surface 16 is completely flat. According to this embodiment, the depth of the recess 14 can be measured using the flat surface (first base surface 16) as a reference surface. If the first base surface 16 were recessed, the recess 14 would have different depths depending on the measurement position within the first base surface 16, making it difficult to measure the depth of the recess 14. For this reason, the dimensions of the recess 14 according to this embodiment are easy to manage, and the recess 14 is easy to manufacture.

[0054] The Fig. Figure 5 is a schematic cross-sectional view of the piece and the threaded spindle of the first embodiment, taken along the orbit, and is, for clarity, a cross-sectional view taken along line VV in the Fig. 4 is recorded. Fig. Figure 6 is a schematic cross-sectional view of the piece and the threaded spindle of the first embodiment, taken along the axial direction, and, for details, is a cross-sectional view taken along line VI-VI in the Fig. 4 is recorded.

[0055] As in the Fig. As shown in Figure 5, the first floor surface 16 extends linearly in the cutting direction when viewed from the axial direction. As shown in the Fig. As shown in Figure 6, the first base surface 16 extends axially and in a straight line from the cutting direction. That is, the first base surface 16 is a flat surface that extends in the cutting direction and in the axial direction. As shown in the Fig. As shown in Figure 6, the first end face 17 is perpendicular to the first base face 16. As in the Fig. As shown in section 5, the second end face 18 (in the Fig. 5 are only partial end surfaces 13d shown) perpendicular to the first floor surface 16.

[0056] As in the Fig. As shown in Figure 5, a central section 16a of the first floor surface 16 has a smaller distance from the center O1 in the cutting direction (in Fig. (5 not shown) as both ends 16b of the first base surface 16 in the cutting direction. The two ends 16b of the first base surface 16 in the cutting direction have the same depth H2 as the central section (groove base) in the groove width of the outer circumferential track surface 13. Therefore, as in the Fig. Figure 3 shows the first floor surface 16 connected to the central section (grooved floor) in the groove width of the outer circumferential track surface 13 without a step.

[0057] As in the Fig. As shown in Figure 4, piece 5 is symmetrical about a center C (see Figure 4). Fig. 4) The piece 5 has an outer circumferential surface 24, which has a ring-shaped form around the center C. The outer circumferential surface 24 comprises a pair of first lateral surfaces 25 and 25 and a pair of second lateral surfaces 26 and 26. The pair of first lateral surfaces 25 and 25 faces the pair of first end faces 17 and 17. The pair of second lateral surfaces 26 and 26 faces the pair of second end faces 18 and 18.

[0058] The orbit 30 of the piece 5 has an S-shape when viewed from its radially outer side. As the ball 4 moves along the orbit 30, it returns along one track. It should be noted that, although the orbit 30 of the embodiment has an S-shape when viewed from its radially outer side, in the present disclosure the orbit 30 may have a linear shape connecting the threaded spindle-side openings 13b. The present disclosure is not particularly limited. A piece-side opening 31 is provided on a second side surface 26. This causes the ball 4, which rolls on the outer circumferential surface 13 of the threaded spindle 2, to enter the orbit 30 of the piece 5 via the piece-side opening 31.

[0059] As in the Fig. As shown in Figure 2, piece 5 has a radially outwardly directed outer diameter surface 41. Two projections 42 are provided on the outer diameter surface 41. The projections 42 extend in a spiral direction. The two projections 42 are axially spaced apart from each other. Therefore, a groove surface 43 is provided between the two projections 42. The groove surface 43 is radially recessed inwards and extends in a spiral direction.

[0060] As in the Fig. As shown in Figure 6, the projections 42 have a semicircular cross-sectional shape. The projections 42 are located within the inner circumferential surface 6a of the nut 6. The projections 42 and the inner circumferential surface 6a are spaced apart from each other. Furthermore, a thread 6b of the nut 6 is located within the groove surface 43. The groove surface 43 and the thread 6b are spaced apart from each other. From the above, it follows that the nut 6 and the piece 5 do not interfere with each other.

[0061] As in the Fig. As shown in Figure 2, a tongue 40 projects spirally from a projection 42. The tongue 40 has a size H3 (see Figure 2). Fig. 7) in the lateral direction, which gradually decreases towards the distal end 40a of the tongue 40. The tongue 40 has a tapered shape.

[0062] As in the Fig. As shown in Figure 5, the tongue 40 is located within the inner circumferential track surface 6a of the nut 6. The tongue 40 is spaced away from the inner circumferential track surface 6a of the nut 6 and does not come into contact with it. Furthermore, the distal end 40a is located on the radially outer side as a virtual curve M connecting the centers O4 of the balls 4 rolling on the track 8. In addition, in this embodiment, the dimension H4 of a step between the groove base of the inner circumferential track surface 6a and the distal end 40a is small.

[0063] According to the tongue 40 described above, the ball 4, which has entered the orbit 30 from the piece-side opening 31, comes into contact with the distal end 40a of the tongue 40. Furthermore, within the ball 4, the distal end 40a of the tongue 40 comes into contact with a section located on the radially outer side opposite the center O4 of the ball 4 (see ball 4A among several balls 4 in the Fig. 5) Therefore, a load acts on the ball 4 in the direction of the radial inner side. As a result, the path of the ball 4 inclines towards the radially inner side of the track 8 (spiral direction), and the ball 4 enters the orbit 30 without friction. Since the distal end 40a also has a small step H4, the ball 4 moves without friction without getting stuck upon contact with the distal end 40a.

[0064] The piece 5 has a second, radially inwardly directed bottom surface 50. The second bottom surface 50 abuts the first bottom surface 16 of the recess 14. The second bottom surface 50 extends in a straight line in the cutting direction Y. As in the Fig. As shown in Figure 6, the second floor surface 50 extends axially and linearly from the cutting direction Y. That is, the second floor surface 50 is a flat surface that extends in the cutting direction Y and in the axial direction.

[0065] The Fig. Figure 7 is a top view of the embodiment, as seen from the second bottom surface. As shown in the Fig. As shown in Figure 7, a circumferential groove surface 51 is provided on the second base surface 50. The circumferential groove surface 51 is radially recessed outwards from the second base surface 50. The interior of the circumferential groove surface 51 forms the orbit 30. As shown in the Fig. As shown in Figure 6, the circumferential groove surface 51 has a U-shaped cross-section in the direction of the groove width. This means that a bottom opening 53 is provided on the second bottom surface 50. The bottom opening 53 opens the circumferential groove 51 radially inwards. Accordingly, during the production of the part 5, a mold for forming the circumferential groove 51 can be moved (released) radially inwards. Therefore, the part 5 is easier to produce than if the radially inner side of the circumferential groove 51 were closed.

[0066] As in the Fig. 5 and Fig. As shown in Figure 6, the first bottom surface 16 of the depression 14 closes the bottom opening 53. Therefore, as shown in the Fig. Figure 3 shows a section that closes the floor opening 53 of the first floor surface 16 (see between the two virtual lines K54 in the Fig. 3) a rolling surface 54 on which the ball 4, moving through the orbit 30, rolls. The ball 4, moving through the orbit 30, is thus surrounded by the orbital groove surface 51 and the rolling surface 54 and does not come into contact with the thread 6b of the nut 6.

[0067] As in the Fig. As shown in Figure 5, the orbital groove surface 51 has a depth H5 from the second base surface 50 (first base surface 16), which is constant in the longitudinal direction of the orbit 30. In other words, the orbital groove surface 51 has a groove base parallel to the first base surface 16 when viewed in the axial direction. Therefore, the orbit 30 is linear in the axial direction Y. Therefore, the ball 4 moves frictionally.

[0068] Next, an effect of the ball screw drive 1 of the first embodiment is described with reference to the Fig. 8 described. Fig. Figure 8 is a schematic view that schematically depicts a cross-section of the ball screw drive of a comparative example of the first embodiment along the path and the orbit. A virtual line K10 is also shown in the Fig. 8 a curve that connects the centers of the balls 4 rolling on track 8 (outer circumferential track surface 13). A virtual line K11 in the Fig. 8 connects the centers of the spheres 4 that roll on the orbit 30 (first base surface 16). A point K12 is an intersection point between the virtual line K10 and a virtual line K11. A virtual line K13 is a tangent to the virtual line K10 that passes through point K12.

[0069] Furthermore, the effect of the first embodiment is described in comparison to that of the comparative example. The ball screw drive of the comparative example differs from that of the first embodiment in that a base surface 1016 is recessed in the axial direction, as shown in the Fig. 8 shown. In addition, a virtual line connects K1011 in the Fig. 8. The centers of the spheres rolling on the orbit (surface area 1016). 4. A point K1012 is an intersection point between the virtual line K10 and the virtual line K1011. A virtual line K1013 is a tangent to the virtual line K10 that passes through point K1012. A virtual line K1014 is a tangent to the virtual line K1011 that passes through point K1012.

[0070] According to the first embodiment, the ball 4, which has entered the orbit 30 from track 8, comes into contact with the tongue 40 (in the Fig. 8 not shown, see Fig. 5) This causes the ball 4 to change its path towards the radially inner side of the tongue 40 and enter the orbit 30. Here, the path (see the virtual line K10) of the ball 4 moving on the path 8 (outer circumferential surface 13) has an arc shape when viewed in the axial direction. When the ball 4 comes into contact with the tongue 40, the path of the ball 4 is bent towards the radially inner side as the virtual line K10. The path of the ball 4 has a bending angle of θ11.

[0071] In contrast, according to the comparative example, the bending angle at which the ball 4 enters the orbit (base surface 1016) from track 8 (outer circumferential surface 13) is θ1011. The bending angle θ1011 of the comparative example is larger than the bending angle θ11 of the embodiment. This is because, in the comparative example, both ends 1016b of the base surface 1016 are set back radially inwards in the cutting direction. It follows from the above explanations that the small bending angle θ11 smooths the movement of the ball 4 between track 8 and the orbit 30.

[0072] As described above, the ball screw drive 1 of the first embodiment comprises the nut 6, the threaded spindle 2, the multiple balls 4, and at least one or more pieces 5. The inner circumferential track surface 6a is located on the inner circumferential surface of the nut 6. The threaded spindle 2 penetrates the nut 6. The outer circumferential track surface 13 is located on the outer circumferential surface of the threaded spindle 2. The multiple balls 4 are arranged on the track 8 between the outer circumferential track surface 13 and the inner circumferential track surface 6a. The pieces 5 allow the balls 4 to rotate. At least one or more recesses 14 are provided on the outer circumferential surface of the threaded spindle 2. The recesses 14 are offset radially inward and accommodate the pieces 5. Each recess 14 has a first bottom surface 16 that faces radially outward. At least a portion of the first bottom surface 16 is flat.A piece 5 comprises the second base surface 50, the circumferential groove surface 51, the base opening 53, the pair of piece-side openings 31, and the pair of tongues 40. The second base surface 50 abuts the first base surface 16. The surface of the circumferential groove 51 is set back radially outward from the second base surface 50. The interior of the circumferential groove surface 51 forms the orbit 30. The base opening 53 opens the orbit 30 radially inward. The pair of piece-side openings 31 opens the orbit 30 at its circumference and connects the orbit 30 to the track 8. The pair of tongues 40 guides the ball 4, which has entered the orbit 30 from the track 8, radially inward. A section that closes the base opening 53 of the first base surface 16 is the rolling surface 54 of the ball 4 as it moves along the orbit 30.

[0073] According to the first embodiment, the tongue 40 reliably guides the ball 4 radially inwards. This prevents the ball 4 from becoming trapped between the circumferential groove surface 51 and the inner circumferential track surface 6a of the raceway. As a result, the ball 4 rolls smoothly, and damage to the groove shoulder of the circumferential groove surface 51 is avoided. Furthermore, dimensional accuracy can be maintained by using the first bottom surface 16, which is flat, as a reference surface. The recess 14 is easy to produce. Since the orbit 30 of the part 5 opens radially inwards, the part 5 can also be easily manufactured using a mold.

[0074] Furthermore, in the first embodiment, the first floor surface 16 is completely flat.

[0075] According to the first embodiment, the first base surface 16 is easy to form. Furthermore, the path of the ball 4 has a small bending angle when the ball 4 enters the orbit 30. Therefore, the ball 4 moves smoothly between the track 8 and the orbit 30.

[0076] Furthermore, the ball screw drive 1 of the first embodiment extends in the cutting direction Y, in which the first bottom surface 16 intersects the virtual line K1, which extends radially outwards from the center O1 of the threaded spindle 2 in the axial direction. The recess 14 has an annular inner circumferential surface 15 that surrounds the piece 5. The inner circumferential surface 15 has a pair of side surfaces (second end faces 18) that enclose the piece 5 from both sides in the cutting direction Y.

[0077] According to the first embodiment, it is prevented that the piece 5 moves in the cutting direction Y and falls out of the recess 14.

[0078] Next, a ball screw drive of a different embodiment is described. It should be noted that the following description only covers changes compared to the first embodiment. (Second embodiment)

[0079] The Fig. Figure 9 is a top view of a recess of a ball screw drive of a second embodiment, seen in the radial direction. Fig. Figure 10 is a cross-sectional view of the ball screw drive of the second embodiment, recorded along a path and an orbit. Note that a virtual line K16 is shown in the Fig. 10 the first base surface 16 of the first embodiment. A virtual line K51 is the circumferential groove surface 51 of the first embodiment. Therefore, the orbit 30 of the first embodiment is formed between the virtual line K16 and the virtual line K51.

[0080] As in the Fig. As shown in Figure 9, a recess 14 of a threaded spindle 2 of a ball screw drive 1A of the second embodiment differs from that of the ball screw drive 1 of the first embodiment in that the recess 14 is a first bottom surface 16A instead of the first bottom surface 16. The first bottom surface 16A comprises a recessed surface 201 and two flat surfaces 202. The recessed surface 201 is located on a central section 16a in the cutting direction Y. The flat surfaces 202 are located on both sides of the recessed surface 201 in the cutting direction Y.

[0081] As in the Fig. As shown in Figure 10, the recessed surface 201 has an arc shape when viewed from the axial direction. The recessed surface 201 is radially recessed inwards as it approaches the central section 16a in the cutting direction. Furthermore, the central section of the recessed surface 201 is in contact with the virtual line K16. That is, the central section 16a of the recessed surface 201 is equidistant from the center O1 in the cutting direction (in the Fig. 10 not shown) like the first floor surface 16 of the first embodiment.

[0082] Furthermore, a piece 5A of the second embodiment differs from the piece 5 of the first embodiment in that a radially outwardly projecting section 251 is provided in a central section of a circumferential groove surface 51A in the longitudinal direction. Therefore, the circumferential groove surface 51A has a shape corresponding to that of the first base surface 16A. Moreover, the flat surfaces 202 extend in the axial direction and in the cutting direction like the first base surface 16A of the first embodiment.

[0083] As described above, according to the second embodiment, an orbit 30A is non-linear and is a path in which the central section is radially recessed inwards in the longitudinal direction. In other words, the flat surfaces 202 of the first base surface 16A are arranged on the radially outer side compared to the first base surface 16 (see virtual line K16) of the first embodiment. Therefore, the outer circumferential surface 13 has a length L longer (see Fig. 10) than that of the first embodiment, and the load-bearing capacity of the ball screw drive 1A is improved.

[0084] Furthermore, the flat surfaces 202 are arranged at both ends of the first base surface 16A in the cutting direction. Therefore, the bending angle upon entry into the orbit 30A from track 8 is smaller in the second embodiment than in the case where the first base surface 16 is fully recessed, as in the first embodiment. Therefore, the ball 4 also moves smoothly between track 8 and orbit 30 in the second embodiment.

[0085] It should be noted that although the recessed surface 201 of the second embodiment is arc-shaped when viewed axially, in the present disclosure the recessed surface 201 can also be triangular. The present disclosure is not limited to the example shown in the embodiment. (Third embodiment)

[0086] The Fig. Figure 11 is a cross-sectional view of a piece and recess of a ball screw drive of a third embodiment, taken along the axial and radial directions. As shown in the Fig. Figure 11 shows that a component 5B of a ball screw drive 1B of the third embodiment differs from that of the first embodiment in that ribs 60 are provided on the outer circumferential sides of the projections 42. The ribs 60 extend spirally and are also provided on the outer circumferential surface of a tongue 40. According to the third embodiment, the ribs 60 improve the strength of the tongue 40 and prevent damage to the tongue 40.

[0087] Although each embodiment has been described above, the present disclosure may be a ball screw drive, which is described below. (Fourth embodiment)

[0088] The Fig. Figure 12 is a cross-sectional view of a piece and a recess of a ball screw drive of a fourth embodiment, taken along the axial and radial directions. As shown in the Fig. As shown in Figure 12, in a ball screw drive 1C of the fourth embodiment, the distance between a first base surface 16C and a center O1 is defined as h. The distance from the center O1 to a thread 6b of a nut 6 is defined as R. The diameter of the ball 4 is defined as Dw. If a distance L1 between the thread 6b and a groove surface 43 (the part of the outer diameter surface 41 of the piece 5C facing the thread 6b of the nut 6) is 0.2 mm or more and 1.5 mm or less, a thickness L2 of the piece 5C (thickness from the part (groove surface 43) of the outer diameter surface 41 of the piece 5C facing the thread 6b of the nut 6 to the circumferential groove surface 51) is 0.3 mm or more and 1.0 mm or less, and a radial gap L3 of the circumferential surface 30 is 0.05 × Dw or more and 0.25 × Dw or less, a distance h preferably satisfies the following expression (2). R / 2−1.25×Dw−2.5(mm) <h<R / 2−1,05×Dw−0,5(mm)

[0089] If the distance h satisfies expression (2), the value of the distance h is relatively large. This means that the first base surface 16C is arranged radially outwards to extend a track 8. This improves the load-bearing capacity of the ball screw drive 1C.

[0090] The first to fourth embodiments were described above. Although the recesses 14 of the first to fourth embodiments have a pair of second, mutually facing surfaces 18 (see the Fig. 3 and Fig. 4), which enclose the piece 5 from both sides in the cutting direction Y, the present disclosure is not limited to such recesses. In the next, fifth embodiment, a recess without the pair of second end faces 18 is described.

[0091] The Fig. Figure 13 is a perspective view of a recess and a section of the fifth embodiment. A ball screw drive 1D of the fifth embodiment differs from that of the first embodiment in that a section 5D protrudes from a recess 14D of the threaded spindle 2 in the section direction Y. Details are described below.

[0092] The Fig. Figure 14 is a perspective view of a recess of a threaded spindle of the fifth embodiment. The recess 14D of the threaded spindle 2 of the ball screw drive 1D of the fifth embodiment differs from the recess 14 of the first embodiment in that the recess 14D has a pair of openings 150 and 150 that are open on both sides in the cutting direction Y. That is, the recess 14D of the fifth embodiment does not have a pair of second end faces 18 (see the Fig. 3 and Fig. 4) openings that enclose the piece 5 from both sides in the cutting direction Y, so that the piece 5D projects out of the recess 14D in the cutting direction Y. It should be noted that in the present disclosure the pair of openings 150 and 150 can be referred to as two openings.

[0093] Furthermore, the recess 14D of the fifth embodiment, as in the first embodiment, comprises a first bottom surface 16 and a pair of axially opposing first end faces 17 and 17.

[0094] One of the two openings 150 and 150 is open to one side in the cutting direction Y. The other is open to the opposite side in the cutting direction Y. In the fifth embodiment, the pair of openings 150 and 150 is formed, and a wall section forming the pair of second end faces 18 is cut out. Therefore, the first bottom surface 16 and the pair of first end faces 17 and 17 are enlarged more in the cutting direction Y than in the first embodiment. That is, the recess 14D is enlarged more in the cutting direction Y than the recess 14 of the first embodiment. Furthermore, the piece 5D of the fifth embodiment is also enlarged more in the cutting direction Y than the piece 5 of the first embodiment (see the Fig. 13).

[0095] The Fig. Figure 15 shows the recess of the fifth embodiment as seen from the cutting direction. As in the Fig. As shown in Figure 15, an opening 150, viewed from the cutting direction Y, has a square shape along the first bottom surface 16 and the pair of first end faces 17 and 17. In other words, no projection or similar feature extending towards the opening 150 is formed on the first bottom surface 16 or the pair of first end faces 17 and 17. This allows the piece 5 to move in the cutting direction Y along the first bottom surface 16 and the pair of first end faces 17 and 17.

[0096] The Fig. Figure 16 is a cross-sectional view along line XVI-XVI in the Fig. 15. As in the Fig. As shown in Figure 16, the piece 5D can be attached to the recess 14D according to the fifth embodiment by inserting the piece 5D from the cutting direction Y of the recess 14D (see arrow A1 in the Fig. 16). Furthermore, in the fifth embodiment, similar to the recess 14 of the first embodiment, the piece 5D can be attached to the recess 14D by positioning the piece 5D on the radially outer side of the recess 14D and moving the piece 5 radially inwards (see arrow A2 in the Fig. 16) This leads to more choices in the direction in which the 5D piece is attached, and improves the attachment options for the 5D piece.

[0097] Furthermore, in the first embodiment, the threaded spindle-side opening 13b is formed on the second end face 18 (see the Fig. 3 and Fig. 4). In contrast, the threaded spindle-side opening 13b of the fifth embodiment, as shown in the Fig. As shown in Figure 14, the first base surface 16 is formed. Therefore, both ends 16b of the first base surface 16 are cut out in the cutting direction Y through the threaded spindle-side opening 13b.

[0098] The Fig. Figure 17 shows the part of the fifth embodiment as seen from the second base surface. As in the first embodiment, the part 5D has a second base surface 50 which abuts the first base surface 16. In addition, a non-contacting surface 160 is formed on a section of the second base surface 50. The non-contacting surface 160 does not abut the first base surface 16.

[0099] The Fig. Figure 18 is a cross-sectional view of the recess and the piece of the fifth embodiment, taken along a direction orthogonal to the axial direction, and, for details, is a cross-sectional view of the recess and the piece, taken along line XVIII-XVIII in the Fig. 15. As in the Fig. As shown in Figure 18, the non-contacting surface 160 is arranged on the radially outer side of the circular path external threaded spindle surface 213 of the threaded spindle 2 and spaced apart from the circular path external threaded spindle surface 213. Therefore, in the fifth embodiment, a section of the piece 5D is not arranged in the recess 14D, but on the radially outer side of the circular path external threaded spindle surface 213. Sections arranged on the radially outer sides of the circular path external threaded spindle surface 213 of the piece 5D are hereinafter referred to as recess outer thickening sections 161. The recess outer thickening sections 161 are formed at both ends of the piece 5D in the cutting direction Y (see Figure 18). Fig. 17).

[0100] Furthermore, the circular path external threaded spindle surface 213 described above is a threaded spindle surface formed when the outer circumferential surface of the threaded spindle 2 is continuously and helically cut to form the outer circumferential path surface 13. Therefore, the circular path external threaded spindle surface 213 extends helically in the same way as the outer circumferential path surface 13, but is not connected to the orbit 30 of the piece 5D. That is, the sphere 4 is not located on the circular path external threaded spindle surface 213.

[0101] In the ball screw drive 1D of the fifth embodiment described above, the ball 4 is also reliably guided radially inwards by the tongue 40 (see the Fig. 13 and Fig. 18) This prevents the ball 4 from being trapped between the circumferential groove surface 51 and the inner circumferential track surface 6a, as in the first embodiment. It should be noted that, although the first end face 17 of the fifth embodiment extends spirally, as described in the first embodiment, the first end face 17 in the present disclosure can extend in the cutting direction Y. The direction (angle with respect to the cutting direction Y) in which the first end face 17 extends is not specifically limited.

[0102] Next, variant 1 is described, which is obtained by deforming a part of the ball screw drive 1D of the fifth embodiment. (Variant 1)

[0103] The Fig. Figure 19 shows the depression and the piece of variant 1 as seen from the cutting direction. Fig. Figure 20 is a perspective view of the recess of the threaded spindle of variant 1. In a ball screw drive 1E of variant 1, the recess 14D differs from that of the fifth embodiment in that a pair of axially recessed grooves 220 and 220 are formed on the pair of first end faces 17 and 17. Furthermore, the piece 5D of variant 1 differs from that of the fifth embodiment in that a pair of axially projecting projections 230 and 230 are formed on the pair of first side faces 25 and 25. It should be noted that in the present disclosure, the pair of first end faces 17 and 17 can be referred to as a pair of end faces. Similarly, the pair of first side faces 25 and 25 can be referred to as a pair of side faces.

[0104] As in the Fig. As shown in Figure 20, a groove 220 extends in the cutting direction Y. Furthermore, the groove 220 extends to both ends of the first end face 17 in the cutting direction Y. Then, both ends of the groove 220 are opened in the cutting direction Y. As shown in the Fig. As shown in Figure 19, the dimension between the pair of first end faces 17 and 17 is defined as W1. A dimension W2 between the pair of grooves 220 and 220 is greater than W1 (W2 > W1).

[0105] Furthermore, a radial position (height from the first bottom surface 16) of the groove 220 is arranged on the radially innermost side of the first end face 17. Therefore, one end 220a of the groove 220 is connected to the first bottom surface 16 on the radially inner side.

[0106] A projection 230 has the same shape as the groove 220, viewed from the cutting direction Y. Furthermore, the projection 230 extends along a first side surface 25 in the cutting direction Y, although it is not specifically shown. As in the Fig. As shown in Figure 19, the radial position of the projection 230 is located on the radially innermost side of the first side surface 25. Therefore, the projection 230 faces axially towards the groove 220 and enters the groove 220. It should be noted that, in the present disclosure, the projection 230 does not necessarily have to extend in the cutting direction Y, although in the embodiment it does. Furthermore, the projection 230 can extend intermittently in the cutting direction Y.

[0107] With respect to the axial thickness of piece 5E, the thickness W3 between the pair of first side faces 25 and 25 is equal to or less than the thickness W1 between the first end faces 17 and 17 (W1 ≥ W3). Therefore, the pair of first side faces 25 and 25 of piece 5E is not clamped between the first end faces 17 and 17.

[0108] A thickness W4 between the pair of projections 230 and 230 is smaller than the thickness W2 between the pair of grooves 220 and 220 (W2 > W4). Therefore, a dimension sufficient to accommodate the pair of projections 230 within the pair of grooves 220 and 220 is ensured. Furthermore, the thickness W4 between the pair of projections 230 and 230 is greater than the thickness W1 between the pair of first end faces 17 and 17 (W4 > W1).

[0109] In a method for fastening the piece 5D of variant 1, the piece 5D is first positioned in the cutting direction Y of the recess 14D. Next, the pair of projections 230 and 230 are inserted into the pair of grooves 220 and 220, and the piece 5E is pressed towards the recess 14D. This fastens the piece 5D to the recess 14D.

[0110] According to variant 1, the pair of projections 230 and 230 is trapped in the pair of grooves 220 and 220, even when a load acts on the piece 5D in the direction of the radially outer side. This restricts the movement of the piece 5D in the direction of the radially outer side. It should be noted that, although in variant 1 the grooves 220 are formed in both of the pair of first end faces 17 and 17, in the present disclosure only one groove 220 may be formed in one of the pair of first end faces 17 and 17. In such a case, a projection 230, which is to be accommodated in the groove 220, is formed on one of the two first side faces 25 and 25.

[0111] Next, variant 2, which is obtained by deforming variant 1, will be described. (Variant 2)

[0112] The Fig. Figure 21 shows the depression and the piece of variant 2 as seen from the cutting direction. As in the Fig. As shown in Figure 21, a ball screw drive 1F of variant 2 differs from that of variant 1 in that the radial positions of a pair of grooves 220F and 220F and a pair of projections 230F and 230F are changed.

[0113] In particular, the pair of grooves 220F and 220F of the recess 14D is arranged on radially central sections of the first end faces 17. Similarly, the pair of projections 230F and 230F is also arranged on radially central sections of the first side faces 25. In variant 2, as in variant 1, the movement of the piece 5D towards the radially outer side is restricted.

[0114] Although in variants 1 and 2 above the pair of grooves 220 and 220 and the pair of projections 230 and 230 are provided to restrict the movement of the piece 5D in the direction of the radially outer side, the present disclosure can next be specified by variant 3. (Variant 3)

[0115] The Fig. Figure 22 shows the recess and the component of variant 3 viewed in the cutting direction. In a ball screw drive 1G of variant 3, component 5D differs from that of the fifth embodiment in that component 5D is inserted between the pair of first end faces 17 and 17 of the recess 14D. In particular, the dimension between the pair of first end faces 17 and 17 is defined as W5. In contrast, the axial thickness (dimension between the pair of first side faces 25 and 25) W6 of component 5D is greater than the dimension W5 between the pair of first end faces 17 and 17 before component 5D is attached to the recess 14D. That is, component 5D has a fitting allowance for the pair of first end faces 17 and 17 and is press-fitted to the recess 14D. As described above, according to variant 3, the movement to the radially outer side and the movement in the cutting direction Y of component 5D are restricted.

[0116] Note that the 5D pieces of variants 1 and 2 above can move in the cutting direction Y. To restrict the movement of the 5D piece in the cutting direction Y, the content of variant 3 can be applied. In particular, the thickness W3 between the pair of first side faces 25 and 25 can be greater than the thickness W1 between the first end faces 17 and 17 (see the Fig. 19). This causes piece 5D to have an axial fixing allowance for the recess 14D. As a result, the movement of piece 5D in the cutting direction Y is restricted.

[0117] Furthermore, the present disclosure may include variants 4 to 6, described below, to restrict the movement of piece 5D in the cutting direction Y of variants 1 and 2. It should be noted that in the following description, a direction orthogonal to both the axial direction and the cutting direction Y is defined as the orthogonal direction. Moreover, a direction in which the center O1 of the threaded spindle 2 is located as seen from the first bottom surface 16 is defined as the first orthogonal direction Z1 (see the Fig. 23 and similar). A direction opposite to the direction in which the center O1 of the threaded spindle 2 is arranged orthogonally from the first base surface 16 is defined as the second orthogonal direction Z2 (see the Fig. 23 and the like). (Variant 4)

[0118] The Fig. Figure 23 is a cross-sectional view of the depression and the piece of variant 4, taken along the direction orthogonal to the axial direction. As in the Fig. As shown in Figure 23, a ball screw drive 1H of variant 4 differs from that of variant 1 in that the piece 5D has a compression section 161H. The compression section 161H is formed by attaching the piece 5D to the recess 14D and then compressing a recess outer thickening section 161 of the piece 5D from the radially outer side (see arrow A3 in the figure). Fig. 23).

[0119] Furthermore, in variant 4, each of the two recessed outer thickening sections 161 (in the Fig. 23 shows only a recessed outer thickening section 161 - see Fig. 17) compressed. Therefore, a pair of compression sections 161H (the Fig. Figure 23 shows only one compression section (161H) formed on both sides of piece 5D in the cutting direction Y.

[0120] The compression section 161H projects further forward in the first orthogonal direction Z1 than the first base surface 16. This causes the pair of compression sections 161H to be clamped against the circular path external thread spindle surface 213 when a load acts on the piece 5D in the cutting direction Y. This restricts the movement of piece 5H in the cutting direction Y.

[0121] Note that, although in variant 4 the recessed outer thickening sections 161 are upset, in the present disclosure the upsetting sections 161H can be formed by upsetting a section other than the recessed outer thickening sections 161. Furthermore, although the upsetting sections 161H of variant 4 are clamped on the circular path outer threaded spindle surface 213, the upsetting sections 161H in the present disclosure can be clamped on the thread 13a (outer circumferential surface) of the threaded spindle 2. Additionally, although in variant 4 a portion of the piece 5D is upset to be deformed (bent) in the orthogonal direction, in the present disclosure the portion of the piece 5D can be axially deformed to be an upsetting section 161H.

[0122] Although in variant 4 the piece 5D is attached to the recess 14D and then both ends of the piece 5D are compressed in the cutting direction Y, in the present disclosure one end of the piece 5D can be compressed in the cutting direction Y before the piece 5D is attached to the recess 14D.

[0123] Although in variant 4 the pair of compression sections 161H is formed at both ends of the piece 5D in the cutting direction Y, in the present disclosure only one compression section 161H may be formed at one of the two ends of the piece 5D in the cutting direction Y. In such a piece 5D, it is necessary to first form a projection (not shown) which, in the first orthogonal direction Z1, protrudes more than the first bottom surface 16 on one side of the piece 5D in the cutting direction Y at the time of manufacture of the piece 5D. (Variant 5)

[0124] The Fig. Figure 24 shows the section of variant 5 as seen from the second floor surface. Fig. Figure 25 is a cross-sectional view of the ball screw drive of variant 5, taken in the direction orthogonal to the axial direction. As in the Fig. As shown in Figure 24, the piece 5D of variant 4 differs from that of variant 1 in that a cutout surface 162 is formed by cutting out both ends of the piece 5D in the cutting direction Y in an arc shape. The cutout surface 162 is obtained by cutting out the pair of recessed outer thickening sections 161.

[0125] Furthermore, the cutout area 162 is larger than the threaded spindle-side opening 13b when viewed orthogonally. Therefore, as shown in the Fig. 25 shows that a part (edge ​​of the threaded spindle-side opening 13b) of the first bottom surface 16 is not covered by the second bottom surface 50 of a piece 5I.

[0126] Furthermore, a difference from variant 1 is that variant 5 has a compression section 163 on the first bottom surface 16 of the recess 14D. The compression section 163 is formed by attaching the piece 5D to the recess 14D and subsequently compression the edge of the threaded spindle-side opening 13b of the first bottom surface 16. It should be noted that, although not specifically shown, compression sections 163 are formed at both ends of the first bottom surface 16 in the cutting direction Y.

[0127] The compression section 163 projects further in the second orthogonal direction Z2 than the first base surface 16. This causes the pair of compression sections 163 to remain attached to the cutout surface 162 when a load acts on the piece 5D in the cutting direction Y. This restricts the movement of the piece 5D in the cutting direction Y.

[0128] Note that, although in variant 5 the first bottom surface 16 is upset, in the present disclosure the thread 13a of the threaded spindle 2 can be upset. Furthermore, if the upset section 163 is formed in the thread 13a of the threaded spindle 2, it is not necessary for the cutout surface 162 to be formed in the piece 5I. That is, in the present disclosure, the shape of the piece is not particularly affected. Although in variant 5 a part of the threaded spindle 2 is deformed to be deformed (bent) in the orthogonal direction, in the present disclosure the part of the threaded spindle 2 can be axially deformed to form an upset section 163.

[0129] Although in variant 5 the piece 5D is attached to the recess 14D and then the pair of compression sections 163 is formed on both sides of the piece 5D in the cutting direction Y, in the present disclosure one of the pair of compression sections 163 can be formed before the piece 5D is attached to the recess 14D.

[0130] Although in variant 5 the pair of upsetting sections 163 is formed on both sides of the piece 5D in the cutting direction Y, in the present disclosure the upsetting section 163 can be formed at one of the two ends of the piece 5D in the cutting direction Y. In such a recess 14D, it is necessary to form a projection (not shown) beforehand, which protrudes in the second orthogonal direction Z2 more than the first bottom surface 16 at one end of the piece 5D in the cutting direction Y at the time of manufacturing the threaded spindle 2. (Variant 6)

[0131] The Fig. Figure 26 is a perspective view of the deepening of variant 6. Fig. Figure 27 shows the section of variant 6 as seen from the second floor surface. Fig. 28 is a cross-sectional view along line XXVIII-XXVIII in the Fig. 26. As in the Fig. As shown in Figure 26, a ball screw drive 1J of variant 6 differs from that of variant 1 in that two holes 240 are formed in the first bottom surface 16 of the recess 14D of the threaded spindle 2. As shown in the Fig. As shown in Figure 27, piece 5D of variant 6 also differs from that of variant 1 in that two projections 241 are formed on the second bottom surface 50.

[0132] As in the Fig. As shown in Figure 28, the projections 241 engage in the holes 240. This causes the projections 241 to be wedged in the holes 240 when a load acts on the piece 5D in the cutting direction Y. This restricts the movement of the piece 5D in the cutting direction Y.

[0133] Note that in one method for fastening the piece 5D, the piece 5D is positioned in the cutting direction Y of the recess 14D. Next, the pair of projections 230 and 231 are inserted into the pair of grooves 220 and 221, and the piece 5D is pressed toward the recess 14D. In this case, the projections 241 are pressed against the first bottom surface 16 to deform. Then, when the projections 241 overlap the holes 240 in an orthogonal direction, the projections 241 return to their original shape and enter the holes 240. This causes the piece 5D to be fastened to the recess 14D. It should be noted that, although the piece of the present disclosure can be made of metal or resin as described above, in this variant the piece is preferably made of resin, which can be easily elastically deformed.

[0134] Furthermore, the two holes 240 and the two projections 241 are symmetrical about the center C (see the Fig. 4) of piece 5D. This ensures that the projections 241 penetrate the holes 240 even when piece 5D is mounted rotated by 180° relative to the recess 14D. This results in an excellent fastening option for piece 5D.

[0135] It should be noted that, although variant 6 provides for two holes 240 and two projections 241, the present disclosure only requires one or more holes 240 and one or more projections 241. The number of holes 240 and projections 241 may also differ from that provided in variant 6. Furthermore, the holes 240 in the present disclosure are not limited to a specific shape. For example, the holes 240 may have the shape of a hemisphere, a truncated cone, a truncated pyramid, a cone, or a pyramid.

[0136] Although variants 4 to 6 have been described above, in the present disclosure the content of variants 4 to 6 can be applied to variant 3. This more reliably restricts the movement of the piece in the cutting direction Y.

[0137] Although the embodiments and variants have been described above, the circumferential groove surface 51 of the present disclosure can be an angular groove with a square cross-sectional shape. Alternatively, the circumferential groove surface 51 can have a Gothic arch cross-sectional shape and is not limited to having the cross-sectional shapes shown in the embodiments. Furthermore, in the ball screw of each of the first to fourth embodiments, the component can have a fastening allowance at a recess, and the component can be fastened to the recess by pressing it in. Although a recess 14B of the fifth embodiment and the variants has two openings 150 and 150, only one opening 150 is provided in the present disclosure. That is, the recess can be opened only on one side of the cutting direction Y.

[0138] It should be noted that the present disclosure may be a combination of the following configurations. (1) A ball screw drive with: a nut with an inner circumferential surface on an inner circumferential surface; a threaded spindle that penetrates the nut and has an outer circumferential track surface on an outer circumferential surface; several spheres arranged on a track between the outer circumferential surface and the inner circumferential surface, and at least one or more pieces that allow the balls to rotate around, in which at least one or more recesses are provided on the outer circumferential surface of the threaded spindle, which are radially recessed inwards and accommodate the pieces, Each of the depressions has a first bottom surface that points radially outwards, at least part of the first floor surface is flat, each of the pieces includes: a second floor surface adjacent to the first floor surface; a circumferential groove surface that is radially recessed outwards from the second bottom surface and has an interior space that forms a circumferential path; a bottom opening that opens the orbit radially inwards; a pair of piece-side openings that open the orbit at the circumference and connect the orbit to the track; and a pair of tongues that guide the balls that have entered the orbit from the track radially inwards, and a section that closes the bottom opening of the first bottom surface, is a rolling surface for the balls moving on the orbit. (2) The ball screw drive according to (1), where the first floor surface is completely flat. (3) The ball screw drive according to (1), where the first base surface, viewed from an axial direction parallel to the threaded spindle, extends in a cutting direction that intersects a virtual line extending radially outwards from a center of the threaded spindle, a recessed area, which is radially recessed inwards, is provided in a central section of the first floor surface in the cutting direction, and Flat surfaces are provided on both sides of the recessed surface in the cutting direction. (4) The ball screw drive according to one of points (1) to (3), in which each of the tongues has a radially outward projecting rib. (5) The ball screw drive according to one of points (1) to (4), where the first base surface, viewed from an axial direction parallel to the threaded spindle, extends in a cutting direction that intersects a virtual line extending radially outwards from a center of the threaded spindle, Each of the depressions has an inner circumferential surface that has a ring-shaped form and surrounds each of the pieces, and The inner circumferential surface has a pair of side surfaces that enclose each of the pieces from both sides in the cutting direction. (6) The ball screw drive according to one of points (1) to (5), where the distance from the center of the threaded spindle to a thread of the nut is defined as R, the diameter of each of the spheres is defined as Dw, a distance between a part of an outer diameter surface of each of the pieces facing the thread of the nut and the thread of the nut is 0.2 mm or more and 1.5 mm or less, a thickness of the part of the outer diameter surface of each piece facing the thread of the nut up to the circumferential groove surface of 0.3 mm or more and 1.0 mm or less, a radial gap of the orbit is 0.05 × Dw or more and 0.25 × Dw or less, and a distance h between the first base surface and the center of the threaded spindle satisfies the following expression (3). R / 2−1.25×D2−2.5(mm) <h<R / 2−1,05×Dw−0,5(mm) (7) The ball screw drive according to one of points (1) to (4), where the first base surface, viewed from an axial direction parallel to the threaded spindle, extends in a cutting direction that intersects a virtual line extending radially outwards from a center of the threaded spindle, each of the recesses has at least one opening open in the cutting direction, and Each of the pieces can move in the cutting direction along the first floor surface. (8) The ball screw drive according to (7), where each of the depressions has two openings, and the two openings include: an opening that is open to one side in the direction of the cut; and an opening that opens to a different side in the direction of the cut. (9) The ball screw drive according to (7) or (8), in which each of the depressions has a pair of end faces that point in an axial direction, Each of the pieces has a pair of side faces that point in an axial direction and are opposite the pair of end faces, a groove which is axially recessed and extends in the cutting direction, is formed on at least one of the two end faces, and a projection that extends axially and is housed in the groove, is formed on at least one of the two side surfaces. (10) The ball screw drive according to (9), where the groove is formed on both of the pair of end faces, and the projection is formed on both of the pair of side surfaces. (11) The ball screw drive according to one of points (7) to (10), in which each of the depressions has a pair of end faces that point in an axial direction, and Each of the pieces has a fastening allowance in relation to the pair of end faces and is clamped between the pair of end faces. (12) The ball screw drive according to one of points (7) to (11), in which one direction is defined as orthogonal to both the axial direction and the cutting direction, a direction in which a center of the threaded spindle is arranged as seen from the first bottom surface, the orthogonal direction is defined as a first orthogonal direction, and a compression section that projects more than the first base surface in the first orthogonal direction, is formed at at least one of the two ends of each of the pieces in the cutting direction. (13) Ball screw drive according to one of points (7) to (11), where a direction which is orthogonal to both the axial direction and the cutting direction is defined as the orthogonal direction, a direction opposite to a direction in which a center of the threaded spindle, viewed from the first base surface, is defined as a second orthogonal direction, and a compression section, which is arranged on at least one of the two sides of each of the pieces in the cutting direction and projects further in the second orthogonal direction than the first bottom surface, is formed on the threaded spindle. (14) The ball screw drive according to one of points (7) to (11), in which one or more holes are formed on the first floor surface, and A projection is formed on the second floor surface, which is intended to enter each of the holes. List of reference symbols 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J BALL SCREW 2 THREADED SPINDLE 4 BALLS 5, 5A, 5B, 5D PIECES 6 MOTHER 6a Inner Circumferential Area 8 TRAIN 13 Outer Circumferential Area 14, 14D DEEP DEPTH 15 INTERNAL CIRCUMFERENCE AREA 16, 16A FIRST FLOOR SURFACES 17 FIRST FOREHEAD 18 SECOND FOREHEAD 13a THREAD 13b Threaded Spindle Side Opening 13c END SURFACE 13d PARTITION END SURFACE 25 FIRST SIDE 26 SECOND SIDE 30, 30A Circular Route 31 PIECE-SIDED OPENING 40 Tongue 41 Outer diameter area 42 ADVANTAGE 43 Grooved Surface 50 SECOND FLOOR SURFACES 51 Circumferential Groove Area 53 FLOOR OPENING 54 ROLLING AREA 60 RIBS 100 brake calipers 104 ELECTRIC ACTUATOR 120 HOUSINGS 150 OPENING 160 CONTACTLESS AREA 161 DECREASE-OUTER THICKENING SECTION 161H, 163 Compression Section 162 CUTOUT AREA 201 RECESSED AREA 202 FLAT AREA 213 Circular Railway External Thread Spindle Surface 220, 220F NUT 230, 230F ADVANTAGE 240 HOLES 241 ADVANTAGE 251 PREVIOUS SECTION QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2004-225770 A

[0004]

Claims

[1] A ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) comprising: a nut (6) with an inner circumferential surface (6a) on an inner circumferential surface (15); a threaded spindle (2) that penetrates the nut (6) and has an outer circumferential track surface (13) on an outer circumferential surface; several spheres (4) arranged on a track (8) between the outer circumferential track surface (13) and the inner circumferential track surface (6a); and at least one or more pieces (5, 5A, 5B, 5D) that cause the spheres (4) to orbit, wherein at least one or more recesses (14, 14D) which are radially recessed inwards and which accommodate the pieces (5, 5A, 5B, 5D) are provided on the outer circumferential surface of the threaded spindle (2), Each of the depressions (14, 14D) has a first bottom surface (16, 16A) that points radially outwards, at least part of the first floor surface (16, 16A) is flat (202), Each of the pieces (5, 5A, 5B, 5D) includes: a second floor surface (50) adjacent to the first floor surface (16, 16A); a circumferential groove surface (51) which is radially recessed outwards from the second base surface (50) and has an interior space which forms a circumferential path (30, 30A); a bottom opening (53) that opens the orbit (30, 30A) radially inwards; a pair of piece-side openings (31) that open the orbit (30, 30A) at the circumference and connect the orbit (30, 30A) to the track (8); and a pair of tongues (40) that guide the balls (4) that have entered the orbit (30, 30A) from the track (8) radially inwards, and a section that closes the bottom opening (53) of the first bottom surface (16, 16A), is a rolling surface (54) of the balls (4) moving on the orbit (30, 30A). [2] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to claim 1, wherein the first bottom surface (16, 16A) is completely flat. [3] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to claim 1, wherein the first bottom surface (16, 16A), viewed from an axial direction parallel to the threaded spindle (2), extends in a cutting direction which intersects a virtual line extending radially outwards from a center of the threaded spindle (2), a recessed area (201), which is radially recessed inwards, is provided in a central section of the first floor surface (16, 16A) in the cutting direction, and flat surfaces (202) are provided on both sides of the recessed surface (201) in the cutting direction. [4] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 1 to 3, wherein each of the tongues (40) has a radially outwardly projecting rib (60). [5] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 1 to 4, wherein the first base surface (16, 16A), viewed from an axial direction parallel to the threaded spindle (2), extends in a cutting direction which intersects a virtual line extending radially outwards from a center of the threaded spindle (2), each of the depressions (14, 14D) one has an inner circumferential surface (15) which has a ring-shaped form and surrounds each of the pieces (5, 5A, 5B, 5C), and the inner circumferential surface (15) has a pair of side surfaces (25, 26) that enclose each of the pieces (5, 5A, 5B, 5C) from both sides in the cutting direction. [6] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 1 to 5, where R is defined as a distance from the center of the threaded spindle (2) to a thread (13a) of the nut (6), a diameter of each of the spheres (4) is defined as Dw, a distance between a part of an outer diameter surface (41) of each of the pieces (5, 5A, 5B, 5C) facing the thread (13a) of the nut (6) and the thread (13a) of the nut (6) is 0.2 mm or more and 1.5 mm or less, a thickness from the part of the outer diameter surface (41) of each of the pieces (5, 5A, 5b, 5C) facing the thread (13a) of the nut (6) to the circumferential groove surface (51) is 0.3 mm or more and 1.0 mm or less, a radial gap of the orbit (30, 30A) is 0.05 × Dw or more and 0.25 × Dw or less, and a distance h between the first base surface (16, 16A) and the center of the threaded spindle (2) satisfies the following expression (1), R / 2−1.25×Dw−2.5(mm) <h<R / 2−1,05×Dw−0,5(mm) [7] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 1 to 4, wherein the first bottom surface (16, 16A), viewed from an axial direction parallel to the threaded spindle (2), extends in a cutting direction which intersects a virtual line extending radially outwards from a center of the threaded spindle (2), each of the recesses (14, 14D) has at least one opening (150) open in the cutting direction, and Each of the pieces (5, 5A, 5b, 5C) can move in the cutting direction along the first bottom surface (16, 16A). [8] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to claim 7, wherein each of the depressions (14, 14D) has two openings (150), and the two openings (150) comprise: an opening (150) which is open to one side in the direction of cutting; and an opening (150) that is open to another side in the direction of the cut. [9] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to claim 7 or 8, wherein each of the recesses (14, 14D) has a pair of end faces (17, 18) that point in the axial direction, Each of the pieces (5, 5A, 5B, 5C) has a pair of side surfaces (25, 26) that point in the axial direction and are facing the pair of end surfaces (17, 18), a groove (220, 220F) which is axially recessed and extends in the cutting direction, is formed on at least one of the two end faces (17, 18), and a projection (230, 230F) which projects axially and is housed in the groove (220, 220F), is formed on at least one of the two side surfaces (25, 26). [10] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to claim 9, wherein the groove (220, 220F) is formed on both of the pair of end faces (17, 18) and the projection (230, 230F) is formed on both of the pair of side faces (25, 26). [11] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 7 to 10, wherein each of the recesses (14, 14D) has a pair of end faces (17, 18) that point in the axial direction, and Each of the pieces (5, 5A, 5B, 5C) has a fastening allowance with respect to the pair of end faces (17, 18) and is inserted between the pair of end faces (17, 18). [12] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 7 to 11, where a direction orthogonal to both the axial direction and the cutting direction is defined as an orthogonal direction, a direction in which a center of the threaded spindle (2) is arranged as seen from the first base surface (16, 16A), the orthogonal direction is defined as a first orthogonal direction, and a compression section (161H, 163) which projects in the first orthogonal direction more than the first base surface (16, 16A) is formed at at least one of the two ends of each of the pieces (5, 5A, 5B, 5C) in the cutting direction. [13] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 7 to 11, where a direction orthogonal to both the axial direction and the cutting direction is defined as an orthogonal direction, a direction opposite to a direction in which a center of the threaded spindle (2), seen from the first base surface, is defined as a second orthogonal direction to the orthogonal direction, and a compression section (161H, 163) is formed on the threaded spindle (2) on at least one of the two sides of each of the pieces (5, 5A, 5B, 5C) in the cutting direction and projects in the second orthogonal direction more than the first bottom surface (16, 16a). [14] The ball screw drive (1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1J) according to any one of claims 7 to 11, wherein one or more holes (240) are formed on the first bottom surface (16, 16A), and on the second floor surface (50) a projection (241) is formed which is intended to enter each of the holes (240).

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