ball screw

Abstract

A long hole (7) is formed in a cutout portion (12) of a nut (1) of a ball screw, the long hole being through in a radial direction and having a long side direction along a lead angle θ, and a part of both side surfaces (7a) in the long side direction parallel to each other guides a ball (115). The circulation portion has a first circulation member (2) disposed in the cutout portion (12) so as to abut against a bottom wall surface (12a) of the cutout portion (12) and having a tongue portion (4) accommodated in the long hole (7), a second circulation member (3) disposed in the cutout portion (12) so as to cover the first circulation member (2) and having a wall portion (10a) accommodated in the long hole (7) and opposed to the tongue portion (4), and a tube (5) disposed in an abutting surface at which the first circulation member (2) and the second circulation member (3) abut against each other and having a higher strength than materials of the first circulation member (2) and the second circulation member (3) that constitute a part of a ball circulation path.

Description

Technical Field

[0001] This invention relates to ball screws. Background Technology

[0002] As a conventional ball screw device, for example, there are known... Figure 7 The ball screw device shown.

[0003] In this ball screw device 110, a nut 114 is screwed onto a screw shaft 112 that has a helical threaded groove 111 on its outer peripheral surface and extends axially. The nut 114 has a helical threaded groove 113 on its inner peripheral surface that corresponds to the threaded groove 11. The threaded groove 111 of the screw shaft 112 and the threaded groove 113 of the nut 114 are opposite to each other to form a load raceway between them. In this load raceway, a plurality of balls 115, which serve as rolling elements, are filled in a rolling manner.

[0004] A ball return passage 116 extending axially is formed in the wall of the nut 114. Additionally, cutouts 117 are formed at both ends of the nut 114 to open the ends of the ball return passage 116 (see reference). Figure 7 A circulation cover plate (circulation section) 130 is fitted and fixed in the cut 117. The circulation cover plate is used to connect the ball return passage 116 with the load raceway between the two threaded grooves 111 and 113.

[0005] like Figure 8 As shown, the circulation cover plate 130 has a curved ball circulation groove 120 that connects the ball return passage 116 with the load raceway between the two threaded grooves 111 and 113. At the end of the ball circulation groove 120, a tongue 119 is provided to lift the ball 115 rolling in the load raceway between the two threaded grooves 111 and 113. The ball circulation groove 120 and a ball moving surface wider than the ball diameter provided on the radial inner surface of the cut 117 form a circulation passage 121 for the ball 115. This circulation passage 121, along with the load raceway between the two threaded grooves 111 and 113 and the ball return passage 116, forms an infinite circulation path for the ball 115. Furthermore, the rotation of the lead screw 112 (or nut 114) causes the nut 114 (or lead screw 114) to move axially via the rolling of the ball 115.

[0006] Furthermore, in the ball screw described in Patent Document 1, a portion of the ball circulation groove 120 of the circulation cover plate 130 is formed of a ball circulation groove forming component (high-strength material) 131 made of metal with a strength higher than that of the synthetic resin molded body. This ball circulation groove forming component 131 is formed, for example, by stamping sheet metal and is integrally formed with the circulation cover plate 130. Additionally, in Patent Document 1, the radial inner surface of the cut 117 is formed deeper, and an anti-peeling plate, such as a superhard alloy plate, is installed, with this plate surface serving as the ball movement surface of the cut 117. This prevents peeling when the circulating balls collide with the inner surface of the direction-changing part, thus preventing adverse effects on operability due to poor ball circulation.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2004-340220 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] However, the circulation component described in Patent Document 1 is manufactured by insert molding, which requires a structure that physically connects the two components, making the design complex. Moreover, the shape of the circulation component described in Patent Document 1 is unsuitable for slots with small lead widths.

[0012] The present invention was made in view of the above-mentioned problems, and its object is to provide a ball screw that can ensure stable operation by improving the strength of the ball circulation section, and can be applied to situations with small ball pitch, small lead, and large lead in multiple specifications.

[0013] Technical means for solving problems

[0014] The above-mentioned objective of the present invention is achieved by the following structure.

[0015] (1) A ball screw, wherein it comprises:

[0016] A lead screw shaft, wherein a helical thread groove is formed on the outer peripheral surface;

[0017] The nut has a helical thread groove formed on its inner circumferential surface and a slit provided on its outer circumferential surface;

[0018] Ball bearings that roll between the threaded grooves of the lead screw shaft and the threaded grooves of the nut; and

[0019] A circulation section, which forms a ball circulation path for circulating the balls rolling between the two threaded grooves of the lead screw shaft and the nut, is mounted on the cutout portion, wherein...

[0020] An elongated hole is formed within the cutout of the nut, the elongated hole extending radially, with its long side oriented along the lead angle. A portion of each of the two parallel sides along the long side guides the ball.

[0021] The circulation section has:

[0022] A first circulation component is disposed within the cut portion in such a manner as to abut against the bottom wall surface of the cut portion, and has a tongue portion that is accommodated within the elongated hole;

[0023] A second circulation component, disposed within the cutout portion such that it covers the first circulation component, and having a wall portion received within the elongated hole and opposing the tongue portion; and

[0024] The tube is disposed within the contact surface where the first circulation component and the second circulation component abut, and has a higher strength than the material of the first circulation component and the second circulation component that constitute part of the ball circulation path.

[0025] (2) According to the ball screw described in (1), wherein,

[0026] The raised portion of the ball bearing circulation path is formed by the tongue of the first circulation component, the wall of the second circulation component, and the two sides along the length of the elongated hole.

[0027] The direction conversion section of the ball bearing circulation path is composed of the tube.

[0028] Invention Effects

[0029] In the ball screw of the present invention, a ball screw is provided that can ensure stable operation by increasing the strength of the ball circulation section, and can be applied to situations with small ball pitch, small lead, and large lead in multiple row specifications. Attached Figure Description

[0030] Figure 1 In the image, (a) is a side view showing the nut of a ball screw according to an embodiment of the present invention, and (b) is a partial side view showing the cut portion of the nut after the circulation component has been removed.

[0031] Figure 2 In the middle, (a) is along Figure 1 (a) is a cross-sectional view along line II-II, and (b) is a cross-sectional view along line II-II. Figure 1 (a) Sectional view of line II'-II'.

[0032] Figure 3 In the diagram, (a) is the front view of the first circulation component, (b) is the side view of the first circulation component, and (c) is the rear view of the first circulation component.

[0033] Figure 4 In the diagram, (a) is the front view of the second circulation component, (b) is the side view of the second circulation component, and (c) is the rear view of the second circulation component.

[0034] Figure 5 In the diagram, (a) is the front view of the tube, and (b) is the side view of the tube.

[0035] Figure 6 In the diagram, (a) is the front view of the modified tube, and (b) is the side view of the modified tube.

[0036] Figure 7 This is a cross-sectional view of the main parts of a traditional ball screw.

[0037] Figure 8 It means in Figure 7 An overall perspective view of an example of a circulation cover plate used in a ball screw.

[0038] Explanation of reference numerals in the attached figures

[0039] 1 nut

[0040] 2 First circulation component

[0041] 3 Second circulation component

[0042] 4 tongue

[0043] 5 tubes

[0044] 7 elongated holes

[0045] 8, 9 Main body sections

[0046] 10a Wall

[0047] 11 Threaded groove

[0048] 12. Incision site

[0049] 111 Threaded groove

[0050] 112 Leadscrew Shaft

[0051] 115 ball bearings Detailed Implementation

[0052] Hereinafter, a ball screw according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the ball screw of the present invention is characterized by its nut and recirculation portion; regarding the screw shaft and balls, which are structural components, please refer to... Figure 7 The conventional lead screw 112 and ball bearing 115 are shown.

[0053] like Figure 1 As shown, the metal nut 1 is formed in a cylindrical shape, with a spiral thread groove 11 formed on its inner circumferential surface.

[0054] Furthermore, on the outer peripheral surface of the nut 1, there are two cutouts 12 formed at two locations that cut radially outward. In addition, an elongated hole 7 is formed in each cutout 12 that extends radially and opens corresponding to the threaded groove 11 formed on the inner peripheral surface.

[0055] Furthermore, a first circulation component 2 and a second circulation component 3, as well as a tube 5, are installed at the cut-out portion 12. The first circulation component 2, the second circulation component 3, and the tube 5 form a ball circulation path that circulates the balls 115 that roll between the two threaded grooves 111, 11 of the lead screw shaft 112 and the nut 1.

[0056] like Figure 1 As shown in (b), two bottom wall surfaces 12a and 12b, parallel to and parallel to the central axis of the nut 1, are formed in a stepped manner at the cutout portion 12. Inner wall surfaces 12c, 12d, and 12e are formed radially on both sides of the axial direction of the two bottom wall surfaces 12a and 12b. In addition, bottom wall surface 12a is longer than bottom wall surface 12b on one side of the axial direction. Furthermore, a countersunk portion 12f is formed on a portion of the bottom wall surface 12a adjacent to the elongated hole 7 in the length direction.

[0057] The elongated hole 7 is formed along the lead angle θ of the thread groove 11 in the longitudinal direction, and is formed to have the same width as the thread groove 11. The elongated hole 7 is used to guide the ball 115 when the circulation part is installed in the cut-out part 12 and forms a lifting part that lifts the ball 115 in the elongated hole 7, with a portion of the two parallel long side surfaces 7a guiding the ball 115.

[0058] In addition to the aforementioned lifting section, the circulation section within the ball circulation path also constitutes a direction conversion section, which converts the movement direction of the lifted ball 115 from the direction of the lifting section along the lead angle θ to the axial direction toward other circulation sections.

[0059] Specifically, such as Figure 3 As shown, the first circulation component 2 has: a main body 8, which forms a semi-cylindrical tube receiving groove 8a that accommodates a portion (half) of the tube 5; and a tongue 4, which is accommodated in the elongated hole 7.

[0060] In addition, such as Figure 4As shown, the second circulation component 3 has: a main body 9, which has a semi-cylindrical tube receiving groove 9a formed on its back side that abuts against the surface of the first circulation component 2, for receiving the remaining portion (half) of the tube 5; and an extension 10, which is continuously formed from the surface of the main body 9, and has a wall portion 10a constituting a raised portion on its back side. The abutting surface of the main body 9 that abuts against the main body 8 of the first circulation component 2 is set to be approximately the same size as the surface of the main body. In addition, the back side of the extension 10 other than the wall portion 10a abuts against the bottom wall surface 12b of the cut-out portion 12.

[0061] And, as Figure 5 As shown, tube 5 is a curved cylindrical component that forms the direction conversion path of the ball circulation path, and is disposed in two tube receiving grooves 8a and 9a on the abutment surfaces of the first circulation component 2 and the second circulation component 3. The tube 5 is made of a material with higher strength than the material of the first circulation component 2 and the second circulation component 3 (resin in this embodiment), such as metal.

[0062] In addition, the tube 5 is formed into an arc shape with a single curvature, but a straight section can also be provided at at least one end, or the tube 5 can be exposed at both ends of the circulation section.

[0063] Additionally, tube 5 can also hold a pair Figure 6 The tube segments 5a shown are combined in a bisected manner. Such tube segments 5a can also be manufactured by stamping or other processes.

[0064] The first circulation component 2 is disposed within the cutout portion 12 such that it abuts against the bottom wall surface 12a of the cutout portion 12, and the tongue portion 4 is disposed within the elongated hole 7. Furthermore, the second circulation component 3 is disposed within the cutout portion 12 such that it covers the first circulation component 2. At this time, the wall portion 10a of the second circulation component 3 is accommodated within the elongated hole 7 and faces the tongue portion 4.

[0065] Therefore, the raised part of the ball circulation path is composed of the tongue 4 of the first circulation component 2, the wall 10a of the second circulation component 3, and the two side surfaces 7a of the long side of the elongated hole 7.

[0066] Furthermore, the first circulation component 2, the tube 5, and the second circulation component 3 can be assembled sequentially within the cutout portion 12, or they can be assembled within the cutout portion 12 in an assembled state.

[0067] Therefore, by using the tube 5 in the direction conversion section, the ball screw of this embodiment can ensure stable operation by increasing the strength of the ball circulation section. Furthermore, by using the two sides 7a of the elongated hole 7 formed in the nut 1 in the length direction in the lifting section, it can also be applied to ball screws with small ball pitch, small lead, and large lead of multiple specifications.

[0068] The present invention is not limited to the above embodiments and variations, and can be modified and improved as needed.

[0069] In this embodiment, the ball recirculation path is constructed by connecting a portion of the two cutouts 12 and directly connecting the two recirculation parts installed in each cutout 12. However, for example, it can also be constructed according to the axial length of the nut 1, and... Figure 7 Similarly, a ball return passage extending axially between the two circulation sections is formed on nut 1.

[0070] Furthermore, the ball screw of the present invention is used, for example, for positioning purposes in high-precision machining and measurement devices, and for XY stages used in semiconductor manufacturing. Additionally, the ball screw is used, for example, in machine tools (machining centers, lathes, grinding machines, etc.), measuring machinery (three-dimensional measuring instruments), and semiconductor manufacturing equipment (exposed equipment, inspection probes, and other worktables).

[0071] Furthermore, this application is based on Japanese Patent Application No. 2021-062356, filed on March 31, 2021, the contents of which are incorporated herein by reference.

Claims

1. A ball screw, characterized in that, have: A lead screw shaft, wherein a helical thread groove is formed on the outer peripheral surface; The nut has a helical thread groove formed on its inner circumferential surface and a slit provided on its outer circumferential surface; Ball bearings that roll between the threaded grooves of the lead screw shaft and the threaded grooves of the nut; as well as A circulation section, wherein the circulation section forms a ball circulation path for circulating the balls that roll between the two threaded grooves of the lead screw shaft and the nut, the circulation section being installed in the cutout section, wherein... An elongated hole extending radially is formed within the cutout portion of the nut. The long side of the elongated hole is formed along the lead angle so that it has two parallel side surfaces along the long side of the lead angle. The circulation section has: A first circulation component is disposed within the cut portion in such a manner as to abut against the bottom wall surface of the cut portion, and has a tongue portion that is accommodated within the elongated hole; A second circulation component, disposed within the cutout portion such that it covers the first circulation component, and having a wall portion received within the elongated hole and opposing the tongue portion; and The tube is disposed within the contact surface where the first circulation component and the second circulation component abut, and the strength of the tube is higher than that of the materials of the first circulation component and the second circulation component, which constitute part of the ball bearing circulation path. In addition to being guided by the circulation section, the ball bearing is also guided by a portion of the two parallel sides of the long side of the elongated hole.

2. The ball screw according to claim 1, characterized in that, The raised portion of the ball bearing circulation path is formed by the tongue of the first circulation component, the wall of the second circulation component, and the two sides along the length of the elongated hole. The direction conversion section of the ball bearing circulation path is composed of the tube.

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