Ball screw

Abstract

To provide a compact external circulation type ball screw capable of fixing a circulation module to a nut with a small number of components even through nut processing is easy.SOLUTION: A circulation module 40 in a ball screw 10 with nut insertion parts 42 engaged in through holes 32 of a nut 30 and a direction changing part 43 for changing a movement direction of a ball continuously provided includes pairs of circulation units 41, 41 constituting a partial passage of a ball circulation path, and connection fixing units 50 arranged between the pairs of circulation units 41, 41 to constitute a remaining portion passage communicating with the partial passage of the circulation unit 41. The circulation unit 41 has a pressure receiving portion provided at each of end parts opposite from a nut insertion part 42 in the direction changing part 43, and the connection fixing units 50 include a fixing part to be fixed to the nut 30 and a pressure regulation part provided on both opening end sides of the remaining portion passage to press each pressure receiving portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an external circulation type ball screw. [Background technology]

[0002] Ball recirculation type ball screws used in machine tools and the like require the balls, which are arranged in a spiral ball rolling path (load track) consisting of a raceway groove in the screw shaft and a raceway groove in the nut, to be scooped up from the ball rolling path and returned from one end of the ball rolling path to the other. Known ball circulation systems include the tube type, the top type (also called the deflector type), the end cap type, and the end deflector type.

[0003] Of these, external circulation type ball screws, which circulate balls outside the nut, are equipped with a circulation component (circulation module) that has a ball circulation path for picking up and circulating balls rolling in the ball rolling path.

[0004] For example, the external circulation type ball screw disclosed in Patent Document 1 includes a screw shaft, a nut, a circulation member (circulation module), and a fixed module. The nut is attached to the screw shaft and has a storage groove and two return holes. The return member has the second connecting portions of the two return pipes connected to each other, and the first connecting portions at both ends are inserted separately into the return holes of the nut. The assembled screw shaft, nut, and return member form a circulation path that keeps the balls rolling.

[0005] The fixing module includes two fixing units and a connecting unit located between the two fixing units. Each of the two fixing units has a first fixing groove, and the connecting unit has a second fixing groove. The first fixing groove and the second fixing groove are fitted to the return member, and the first fixing groove corresponds to a curved portion connecting the first connecting portion and the second connecting portion of the return pipe.

[0006] The fixing module fits into the storage groove of the nut, covers the return member, and is screwed onto the nut to fix the return member to the nut. Thus, the fixing module can reliably fix the return member to the nut without causing misalignment between the mating surfaces of the second connecting portions of the two return pipes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Utility Model Registration No. 3232612 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the external circulation ball screw of Patent Document 1, in order to fix the outer surface of the return pipe so that there is no misalignment at the mating surfaces of the two return pipes that make up the return member, a fixing module consisting of two fixing units and a connection unit is used to screw it onto the nut, which has the problem that the fixing module has a large number of parts and is prone to becoming large.

[0009] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a compact external circulation type ball screw that can fix a circulation module to a nut with a small number of parts. [Means for solving the problem]

[0010] The above object of the present invention can be achieved by the following configuration. a screw shaft having a spiral screw shaft-side raceway groove formed on its outer peripheral surface; a nut having an inner peripheral surface formed with a spiral nut-side raceway groove facing the screw shaft-side raceway groove, and having at least a pair of through holes communicating with the outer peripheral surface and the nut-side raceway groove; a plurality of balls rolling in a ball rolling path formed by the screw shaft side raceway groove and the nut side raceway groove; a circulation module attached to the pair of through holes and forming a ball circulation path for circulating the balls rolling in the ball rolling path, The circulation module includes: a pair of circulation units each including a cylindrical nut insertion portion that is fitted into the through hole and a direction change portion that changes the moving direction of the ball, the pair of circulation units constituting a part of the ball circulation path; a connecting and fixing unit disposed between the pair of circulation units and constituting a remaining path of the ball circulation path that communicates with a portion of the ball circulation path in each of the pair of circulation units, The pair of circulation units each have a pressure-receiving portion provided at an end of the direction change portion opposite the nut insertion portion, The connection and fixation unit has a fixing portion fixed to the nut and pressure-reducing portions provided on both open end sides of the remaining portion path and each pressing down on the pressure-receiving portion. A ball screw characterized by: [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a compact external circulation type ball screw that can fix a circulation module with a nut using a small number of parts.

[0012] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a ball screw according to one embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing a nut of the ball screw shown in FIG. [Figure 3] FIG. 3 is a perspective view of the ball screw circulation module shown in FIG. 1 as viewed obliquely from above. [Figure 4] FIG. 4 is a perspective view of the ball screw circulation module shown in FIG. 1 as viewed obliquely from below. [Figure 5] 5 is a perspective view showing a pair of circulation units in the circulation module shown in FIG. [Figure 6] 6 is a perspective view showing a connection and fastening unit in the circulation module shown in FIG. [Figure 7] FIG. 7 is a perspective view showing a single piece of a pair of molded parts that constitute the connection and fastening unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] A ball screw according to an embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a perspective view showing a ball screw 10 according to one embodiment of the present invention. Fig. 2 is a perspective view showing a nut 30 of the ball screw 10 shown in Fig. 1.

[0015] As shown in FIG. 1, the ball screw 10 according to this embodiment is an external circulation type ball screw including: a screw shaft 20 having a spiral screw shaft-side raceway groove 21 formed on its outer peripheral surface; a nut 30 having a spiral nut-side raceway groove 31 formed on its inner peripheral surface facing the screw shaft-side raceway groove 21 and having two pairs of through holes 32 connecting the outer peripheral surface 33 and the nut-side raceway groove 31; a plurality of balls (not shown) that roll in a ball rolling path 25 formed by the screw shaft-side raceway groove 21 and the nut-side raceway groove 31; and a circulation module 40 attached to the pair of through holes 32 and forming a ball circulation path 60 that circulates the balls rolling in the ball rolling path 25.

[0016] As shown in Figure 2, the metal nut 30 is formed in a cylindrical shape with an annular flange 35 formed at one end. A plurality of mounting holes 35a are formed in the flange 35 and penetrate the flange 35 in the axial direction. A spiral nut-side raceway groove 31 is formed on the inner peripheral surface of the nut 30 with the same lead as the screw shaft-side raceway groove 21. In addition, a mounting surface 33a parallel to the axis O of the nut 30 is formed on the outer peripheral surface 33 of the nut 30.

[0017] Furthermore, two pairs (four) of through holes 32, each having a circular cross section, are formed at both axial ends of the mounting surface 33a. The through holes 32 penetrate obliquely inward along the lead angle of the nut-side raceway groove 31 and communicate with the nut-side raceway groove 31. The through holes 32 communicate with the space within the ball rolling path 25 formed in the ball screw 10.

[0018] Two circulation modules 40, which form a ball circulation path that circulates the plurality of balls rolling in the ball rolling path 25, are attached adjacent to each other on the mounting surface 33a of the nut 30. The mounting surface 33a is provided with four screw holes 37 into which screws 71 are threaded. Each of the screw holes 37 has a circular recess 38 formed on the opening edge, giving it a stepped shape. The two circulation modules 40 are fixed to the nut 30 by the screws 71 that thread into the screw holes 37 of the nut 30.

[0019] The balls are spherical bodies made of steel such as alloy steel, and roll in a ball rolling path 25 consisting of opposing screw shaft side raceway grooves 21 and nut side raceway grooves 31 to threadably engage the screw shaft 20 and the nut 30 and support the load applied to the ball screw 10.

[0020] 3 and 4 are perspective views of the circulation module 40 of the ball screw 10 shown in Fig. 1, viewed obliquely from above and below. Fig. 5 is a perspective view showing a pair of circulation units 41, 41 in the circulation module 40 shown in Fig. 3.

[0021] As shown in FIGS. 3 and 4, the circulation module 40 has a pair of circulation units 41, 41, and a connection and fixing unit 50 disposed between the pair of circulation units 41, 41.

[0022] The circulation unit 41 is provided with a cylindrical nut insertion portion 42 that fits into the through hole 32 of the nut 30 and a direction change portion 43 that changes the moving direction of the balls, which are provided successively. The nut insertion portion 42 has a ball scooping portion 42a at its tip that protrudes into the ball rolling path 25 and scoops up the balls.

[0023] The circulation unit 41 forms a partial path 61 of the ball circulation path 60 for changing the direction of movement of the scooped balls so that they move from the direction of the ball scooping section 42a along the lead angle to the other circulation section along the axial direction.

[0024] As shown in FIG. 5, pressure-receiving portions 45 are provided at the ends of the circulation unit 41 on the opposite side of the direction change portions 43 from the nut insertion portions . The pressure-receiving portion 45 of this embodiment has an upper pressure-receiving surface 45a and side pressure-receiving surfaces 45b, 45b, which are pressure-receiving surfaces formed on the upper surface and both side surfaces of the direction changing portion 43. The upper pressure-receiving surface 45a and the side pressure-receiving surfaces 45b, 45b are stepped surfaces that are lower than the outer peripheral surface of the direction changing portion 43.

[0025] The direction changer 43 of this embodiment is configured as a polyhedron with a multifaceted exterior surface. A bottom surface 47 facing the mounting surface 33a of the nut 30 can be in surface contact with the mounting surface 33a. Furthermore, a longitudinal end surface 48 on the nut insertion portion 42 side can be in surface contact with a side surface 58 of the connection and fixing unit 50 of the adjacent circulation module 40, as will be described later.

[0026] Furthermore, the circulation unit 41 of this embodiment is composed of a pair of molded parts 41a, 41b each having a semicircular cross-sectional rolling surface 61a, 61b that is divided into two along a partial path 61 of the ball circulation path 60. These molded parts 41a, 41b define the partial path 61 of the ball circulation path 60 for circulating the balls with the rolling surfaces 61a, 61b.

[0027] In addition, since these molded parts 41a and 41b constitute the partial path 61, which is a complex path made up of a combination of curves, it is preferable that they be formed by injection molding of synthetic resin, which allows a high degree of freedom in shape, or sintering molding using metal powder. These molded parts 41a and 41b are formed separately and then joined together with fixing screws or the like.

[0028] Fig. 6 is a perspective view showing the connection and fastening unit 50 in the circulation module 40 shown in Fig. 4. Fig. 7 is a perspective view showing a single item in a pair of molded parts 51, 51 that constitute the connection and fastening unit 50 shown in Fig. 6.

[0029] As shown in FIG. 6, the connection and fixing unit 50 constitutes the remaining passages 63 of the ball circulation path 60 which communicate with the partial passages 61 of the ball circulation path 60 in the pair of circulation units 41, 41, respectively. The connection fixing unit 50 has a pair of fixing portions 52, 52 provided at both ends for fixing to the nut 30, and a pair of pressure control portions 59, 59 provided on both open end sides of the remaining portion path 63 for respectively pressing down the pressure-receiving portions 45 of the pair of circulation units 41, 41.

[0030] The pressure control portion 59 of the connecting and fixing unit 50 according to this embodiment has an upper pressure control surface 59a and a side pressure control surface 59b, 59b (pressure control surfaces) that respectively face the upper pressure receiving surface 45a and the side pressure receiving surfaces 45b, 45b (pressure receiving surfaces) of the circulation unit 41, and can respectively hold down the pressure receiving portions 45 of the pair of circulation units 41, 41. Furthermore, the upper pressure receiving surface 45a and the side pressure receiving surfaces 45b, 45b, which are stepped surfaces, are less likely to become misaligned with the upper pressure control surface 59a and the side pressure control surfaces 59b, 59b.

[0031] Furthermore, in the fixing portion 52 of the connection fixing unit 50 according to this embodiment, a stepped hole 53 is formed toward the screw hole 71 so that the threaded portion 71a of the screw 71 that screws into the screw hole 37 of the nut 30 can pass through. By threading the threaded portion 71a of the screw 71 that has been inserted into the stepped hole 53 into the screw hole 37 of the nut 30, the connection fixing unit 50 can be fixed to the mounting surface 33a of the nut 30.

[0032] The connection and fastening unit 50 of this embodiment is configured as a polyhedron with a multifaceted exterior surface. The bottom surface 57 facing the mounting surface 33a of the nut 30 can be in surface contact with the mounting surface 33a. Furthermore, the side surface 58 can be in surface contact with the longitudinal end surface 48 of the adjacent circulation module 40 on the nut insertion portion 42 side, as described above (see FIG. 1). Therefore, the circulation module 40, which is made up of the pair of circulation units 41, 41 and the connection and fastening unit 50, and the nut 30 can be firmly fixed together by surface-to-surface contact with each other.

[0033] Furthermore, the connection and fixing unit 50 of this embodiment is composed of a pair of molded parts 51, 51 having a symmetrical shape divided into two along the central axis of a pair of stepped holes 53, 53, and the stepped hole 53 is formed between the mating surfaces 54, 54 of the pair of molded parts 51, 51.

[0034] Therefore, as shown in FIG. 7, a molded part 51 having a pair of recesses 53 a, 53 a with a semicircular cross-sectional inner surface on the mating surface 54 and a remaining portion path 63 with a circular cross-section penetrating in the mating direction of the mating surface 54 has an outer shape without an undercut shape that can be molded as a single unit using two molds that are released in the mating direction of the mating surface 54.

[0035] That is, the connecting and fixing unit 50 is made up of a pair of molded parts 51, 51 that do not have an undercut shape. Therefore, the molding die for the molded part 51 that makes up the connecting and fixing unit 50 does not need to be complicated, and manufacturing costs can be reduced.

[0036] Furthermore, a cylindrical anti-splitting protrusion 55 is provided on the opening edge of the stepped hole 53 facing the screw hole 37, and fits into the recess 38 formed on the opening edge of the screw hole 37. The anti-splitting protrusion 55 is provided on each of the pair of molded parts 51, 51 in the shape of a split semicircular cross section.

[0037] When attaching the circulation module 40 to the nut 30, first, the nut insertion portions 42 are inserted into the corresponding through holes 32 of the nut 30, and the direction change portions 43 are placed on the attachment surface 33a, so that a pair of circulation units 41, 41 are positioned on the outer surface 33 of the nut 30.

[0038] In this case, since there is space between the pair of circulation units 41, 41 for arranging the connection and fixing unit 50, it is possible to check the step in the partial path 61 of the circulation unit 41 during assembly. As a result, the operability and durability of the ball screw 10 can be improved.

[0039] Next, the connecting and fixing unit 50 is interposed between the pair of circulation units 41, 41 so that the pair of pressure control portions 59, 59 of the connecting and fixing unit 50 cover the pressure receiving portions 45, 45 of the pair of circulation units 41, 41, respectively.

[0040] Furthermore, when the upper pressure control surface 59a of the pressure control portion 59 of the connection fixing unit 50 is inserted until it abuts against the upper pressure receiving surface 45a of the pressure receiving portion 45 of the circulation unit 41, the half-shaped anti-splitting protrusions 55 protruding from each of the pair of molded parts 51, 51 fit into the recess 38.

[0041] Then, a screw 71 is inserted into the stepped hole 53 in the fixing portion 52 of the connection and fixing unit 50, and the threaded portion 71a is screwed into the threaded hole 37 of the nut 30 and tightened until the bottom surface 57 of the connection and fixing unit 50 abuts against the mounting surface 33a. Then, the upper pressure-receiving surface 45a of the pressure-receiving portion 45 is pressed by the upper pressure-suppressing surface 59a of the pressure-suppressing portion 59, so that the pair of circulation units 41, 41 are fixed to the nut 30 by the connection and fixing unit 50.

[0042] At this time, the side pressure receiving surfaces 45b, 45b of the pressure receiving portion 45 are pressed by the side pressure suppressing surfaces 59b, 59b of the pressure suppressing portion 59, so that the pair of molded parts 41a, 41b in the circulation unit 41 are restricted from moving in a direction in which their mating surfaces move away from each other.

[0043] Furthermore, the pair of molded parts 51, 51 in the connecting and fixing unit 50 have their separation prevention projections 55 fitted into the recesses 38 of the nut 30, so that the mating surfaces 54, 54 are restricted from moving apart from each other.

[0044] Then, when a pair of circulation units 41, 41 and a connection and fixing unit 50, which are combined together, are fixed to a nut 30, two partial paths 61 in the pair of circulation units 41, 41 and one remaining path 63 in the connection and fixing unit 50 are connected, thereby forming a ball circulation path 60 of the circulation module 40.

[0045] Therefore, according to the ball screw 10 of this embodiment, the circulation module 40 can be configured with only the pair of circulation units 41 and 41 and the connection and fixing unit 50, and the circulation module 40 can be fixed to the nut 30.

[0046] Furthermore, in the ball screw 10 according to this embodiment, the connection and fixation unit 50 is configured from a pair of molded parts 51, 51 that do not have an undercut shape. Therefore, the molded part 51 that configures the connection and fixation unit 50 does not require a complex molding die, and manufacturing costs can be reduced.

[0047] Furthermore, in the ball screw 10 according to this embodiment, the pair of circulation units 41, 41 are each composed of a pair of molded parts 41a, 41b that are split into two along a partial path 61 of the ball circulation path 60. Therefore, in order to configure the partial path 61, which is a complex path made up of a combination of curves, the molded parts 41a, 41b can be easily formed by injection molding of synthetic resin, which has a high degree of freedom in shape, sinter molding using metal powder, or the like.

[0048] Furthermore, in the ball screw 10 according to this embodiment, the direction changing section 43 of the circulation module 40 and the connection and fixing unit 50 are each configured as a polyhedron and are combined in a state of surface contact with each other. Furthermore, an attachment surface 33a parallel to the axis O of the nut 30 is formed on the outer peripheral surface 33 of the nut 30, and the direction changing section 43 and the connection and fixing unit 50 are fixed in a state of surface contact with the attachment surface 33a. Thus, the circulation module 40, which is made up of a pair of circulation units 41, 41 and the connection and fixing unit 50, and the nut 30 can be firmly fixed together by surface-to-surface contact with each other.

[0049] Furthermore, in the ball screw 10 according to this embodiment, two circulation modules 40, 40 are attached to the nut 30 to form two rows of ball circulation paths 60, and the side surface 58 of the connection and fixing unit 50 can come into surface contact with the longitudinal end surface 48 on the nut insertion portion 42 side of the adjacent circulation module 40. Thus, these two circulation modules 40, 40 and the nut 30 can be firmly fixed together by their surface-to-surface contact with each other.

[0050] As described above, the ball screw 10 of this embodiment can provide a compact external circulation type ball screw that can fix the circulation module with a nut using a small number of parts.

[0051] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. Furthermore, the material, shape, size, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0052] The ball screw of the present invention is used, for example, in XY stages used for positioning devices that perform high-precision processing and measurement, and in semiconductor manufacturing, etc. The ball screw is also used, for example, in machine tools (machining centers, lathes, grinders, etc.), measuring machines (three-dimensional measuring devices), semiconductor manufacturing equipment (tables for exposure devices, inspection probes, etc.), etc.

[0053] Here, the features of the above-described embodiments of the ball screw according to the present invention will be briefly summarized and listed below in [1] to [7].

[0054] [1] A screw shaft (20) having a spiral screw shaft side raceway groove (21) formed on its outer circumferential surface; a nut (30) having a spiral nut-side raceway groove (31) formed on its inner peripheral surface, the spiral nut-side raceway groove (31) facing the screw shaft-side raceway groove (21), and having at least a pair of through holes (32, 32) communicating between its outer peripheral surface (33) and the nut-side raceway groove (31); a plurality of balls rolling in a ball rolling path (25) formed by the screw shaft side raceway groove (21) and the nut side raceway groove (31); a circulation module (40) attached to the pair of through holes (32, 32) and forming a ball circulation path (60) for circulating the balls rolling in the ball rolling path (25), The circulation module (40) a pair of circulation units (41, 41) each including a cylindrical nut insertion portion (42) fitted into the through hole (32) and a direction change portion (43) for changing the direction of movement of the balls, the pair of circulation units forming a part of a path (61) of the ball circulation path (60); a connecting and fixing unit (50) disposed between the pair of circulation units (41, 41) and constituting a remaining path (63) of the ball circulation path (60) that communicates with a partial path (61) of the ball circulation path (60) in each of the pair of circulation units (41, 41), The pair of circulation units (41, 41) each have a pressure-receiving portion (45) provided at an end of the direction-changing portion (43) opposite to the nut insertion portion (42), The connection and fixation unit (50) has a fixing portion (52) fixed to the nut (30) and pressure-reducing portions (59) provided on both open end sides of the remaining portion path (63) and each pressing down on the pressure-receiving portion (45). A ball screw (10) characterized by:

[0055] According to the ball screw (10) having the configuration [1] above, the circulation module (40) can be formed using only a pair of circulation units (41, 41) and a connection and fixing unit (50), and the circulation module (40) can be fixed to the nut 30.

[0056] [2] The connection and fixing unit (50) is composed of a pair of molded parts (51, 51) that do not have an undercut shape. The ball screw (10) according to the above [1].

[0057] According to the ball screw (10) having the configuration [2] above, the molded part (51) constituting the connection and fixing unit (50) does not require a complex molding die, and the manufacturing cost can be reduced.

[0058] [3] A stepped hole (53) is provided in the fixing portion (52) toward the screw hole (37) of the nut (30) so that a threaded portion (71a) of a screw (71) that is to be screwed into the screw hole (37) of the nut (30) can pass through the stepped hole (53). The stepped hole (53) is defined and formed in the mating surfaces (54) of the pair of molded parts (51, 51). An anti-splitting protrusion (55) is provided on the opening edge of the stepped hole (53) facing the screw hole (37), and the protrusion (55) fits into a recess (38) formed on the opening edge of the screw hole (37). The ball screw (10) according to [2] above.

[0059] According to the ball screw (10) having the configuration [3] above, the pair of molded parts (51, 51) in the connection and fixing unit (50) have their half-shaped anti-splitting protrusions (55) fitted into the recesses (38) of the nut (30), so that the movement of their mating surfaces (54, 54) in the direction away from each other is restricted.

[0060] [4] The pair of circulation units are each composed of a pair of molded parts (41a, 41b) split into two along the path of the ball circulation path. The ball screw (10) according to [1] above.

[0061] According to the ball screw (10) having the configuration [4] above, the partial path (61) is configured as a complex path made up of a combination of curves, and therefore, the molded parts (41a, 41b) can be easily formed by injection molding of synthetic resin, which has a high degree of freedom in shape, or sinter molding using metal powder.

[0062] [5] The pressure-receiving surface of the pressure-receiving portion is a stepped surface that is lower than the outer peripheral surface of the direction-changing portion, The pressure control surface of the pressure control portion presses the pressure receiving surface. The ball screw (10) according to [4] above.

[0063] According to the ball screw (10) having the configuration [5] above, the pressure control portion (59) of the connection and fixing unit (50) has pressure control surfaces (upper pressure control surface 59a and side pressure control surfaces 59b, 59b) that face the pressure receiving surfaces (upper pressure receiving surface 45a and side pressure receiving surfaces 45b, 45b) of the circulation unit (41), respectively, and can press down the pressure receiving portions (45) of the pair of circulation units (41, 41). Furthermore, the pressure receiving surfaces (upper pressure receiving surface 45a and side pressure receiving surfaces 45b, 45b) that are stepped surfaces are less likely to be misaligned with the pressure control surfaces (upper pressure control surface 59a and side pressure control surfaces 59b, 59b).

[0064] [6] The circulation module (40) is configured such that the direction changer (43) and the connection and fixing unit (50) are each formed as a polyhedron and are combined in a state of surface contact with each other. The ball screw (10) according to any one of the above items [1] to [5].

[0065] According to the ball screw (10) having the configuration [6] above, the direction change section (43) of the circulation module (40) and the connecting and fixing unit (50) are each configured as a polyhedron and are combined in a state of surface contact with each other. Therefore, the circulation module (40) consisting of a pair of circulation units (41, 41) and the connecting and fixing unit (50) can be firmly fixed by surface-to-surface contact with each other.

[0066] [7] An attachment surface parallel to the axis of the nut is formed on the outer peripheral surface of the nut, The direction changer and the connection and fixation unit are fixed in a state of surface contact with the mounting surface. The ball screw (10) according to [6] above.

[0067] According to the ball screw (10) having the configuration [7] above, the circulation module (40) consisting of a pair of circulation units (41, 41) and a connection and fixing unit (50) and the nut (30) can be firmly fixed to each other by their surfaces coming into contact with each other. [Explanation of symbols]

[0068] 10 Ball screw 20 Screw shaft 21 Screw shaft side raceway groove 25 Ball rolling path 30 nuts 31 Nut side raceway groove 32 through holes 33 Outer surface 40 Circulation Module 41 Circulation Unit 42 Nut insertion part 43 Turning point 45 Pressure-receiving area 50 Connection Fixing Unit 52 Fixed part 59 Suppression Department 60 Ball Circulation Path 61 Partial Route 63 Remaining path

Claims

1. a screw shaft having a spiral screw shaft-side raceway groove formed on its outer peripheral surface; a nut having an inner peripheral surface formed with a spiral nut-side raceway groove facing the screw shaft-side raceway groove, and having at least a pair of through holes communicating with the outer peripheral surface and the nut-side raceway groove; a plurality of balls rolling in a ball rolling path formed by the screw shaft side raceway groove and the nut side raceway groove; a circulation module attached to the pair of through holes and forming a ball circulation path for circulating the balls rolling in the ball rolling path, The circulation module includes: a pair of circulation units each including a cylindrical nut insertion portion that is fitted into the through hole and a direction change portion that changes the moving direction of the ball, the pair of circulation units constituting a part of the ball circulation path; a connecting and fixing unit disposed between the pair of circulation units and constituting a remaining path of the ball circulation path that communicates with a portion of the ball circulation path in each of the pair of circulation units, The pair of circulation units each have a pressure-receiving portion provided at an end of the direction change portion opposite the nut insertion portion, The connection and fixation unit has a fixing portion fixed to the nut and pressure-reducing portions provided on both open end sides of the remaining portion path and each pressing down on the pressure-receiving portion. A ball screw characterized by:

2. The connection and fixation unit is composed of a pair of molded parts that do not have an undercut shape.

2. The ball screw according to claim 1.

3. a stepped hole provided in the fixing portion toward the screw hole for allowing a threaded portion of a screw to be threaded into the screw hole of the nut to pass through the stepped hole is defined and formed on mating surfaces of the pair of molded parts; an anti-splitting protrusion that fits into a recess formed on the opening edge of the screw hole is provided on the opening edge of the stepped hole that faces the screw hole; 3. The ball screw according to claim 2.

4. The pair of circulation units are each composed of a pair of molded parts divided into two along the path of the ball circulation path.

2. The ball screw according to claim 1.

5. The pressure receiving surface of the pressure receiving portion is a stepped surface that is lower than the outer peripheral surface of the direction changing portion, The pressure control surface of the pressure control portion presses the pressure receiving surface.

5. The ball screw according to claim 4.

6. The circulation module is configured such that the direction change unit and the connection and fixing unit are each configured as a polyhedron and are combined in a state of surface contact with each other.

6. The ball screw according to claim 1, wherein the ball screw is a ball screw having a diameter of 100 mm or less.

7. An attachment surface parallel to the axis of the nut is formed on the outer peripheral surface of the nut, The direction changer and the connection and fixation unit are fixed in a state of surface contact with the mounting surface.

7. The ball screw according to claim 6.

Images