WO2007113986A1

WO2007113986A1 - Rolling-body screw device of in-shaft circulation-type

Info

Publication number: WO2007113986A1
Application number: PCT/JP2007/054649
Authority: WO
Inventors: Noriaki Chikamoto; Kentaro Yamamoto
Original assignee: Thk Co., Ltd.
Priority date: 2006-03-30
Filing date: 2007-03-09
Publication date: 2007-10-11

Abstract

An in-shaft circulation-type rolling-body screw device (1) where a screw shaft (3) can be continuously formed in a length greater than the overall axial length of a nut member (2) and where large rotational torque can be inputted. The nut member (2) and the screw shaft (3) are screwed with each other with a large number of rolling bodies (4) placed in between them. A rolling body return path (40) is integrated in the screw shaft (3). The screw shaft (3) is made up of a screw shaft body (32) and a circulation path forming member (33). The screw shaft body (32) is formed in a circular tube shape having a hollow section, has in its outer peripheral surface a rolling groove (30) for the rolling bodies (4), and has a pair of rolling body lead-in holes (34) formed in a penetrating manner in the peripheral wall of the screw shaft body (32) so as to correspond to both ends of the rolling groove (30). The circulation path forming member (33) has the rolling body return path (40), is fixed to the hollow section of the screw shaft body (32), and connects the pair of rolling body lead-in holes (34), formed in the screw shaft body (32), by using the rolling body return path (40).

Description

Specification

In-shaft circulating rolling element screw device

Technical field

[0001] The present invention relates to a plurality of rolling members such as balls and rollers arranged between a nut member and a screw shaft. In particular, the present invention relates to a rolling element screw device that converts the rotational motion of a motor into a linear motion, and more specifically, a rolling element screw that circulates a rolling element through a rolling element return passage provided inside a screw shaft. Relates to the device.

Background art

Conventionally, a ball screw device in which a nut member is screwed onto a screw shaft via a number of balls is known as a device that converts rotational motion into linear motion or linear motion into rotational motion. This type of ball screw device is generally of a type in which the nut member has an infinite circuit of the ball, and in this type of ball screw device, the ball is circulated in the infinite circuit. The nut member can move along the screw shaft without any restriction on the stroke.

[0003] On the other hand, Japanese Patent Laid-Open No. 2003-222220 discloses a ball screw device of a type in which an infinite circulation path for balls is provided on a screw shaft that is not a nut member. In this ball screw device, a ball circulation hole is formed so as to penetrate along the axial direction of the screw shaft, and a pair of ball guide members are attached to both ends of the screw shaft, and are formed on the outer peripheral surface of the screw shaft. The end of the spiral ball rolling groove and the ball circulation hole are connected by the ball guide member. That is, when the ball rolled while applying a load between the screw shaft and the nut member reaches the end of the ball rolling groove of the screw shaft, the ball is guided to the ball circulation hole by one ball guide member. . The ball guided to the ball circulation hole rolls in the ball circulation hole in the axial direction of the screw shaft, and then is returned to the ball rolling groove by the other ball guide member. Roll while applying a load between.

Patent Document 1: Japanese Patent Laid-Open No. 2003-222220 Disclosure of the invention

Problems to be solved by the invention

[0004] Thus, in a ball screw device in which an infinite circulation path of a ball is formed on a screw shaft, the ball rolling groove formed on the outer peripheral surface of the screw shaft is a part of the infinite circulation path, and the ball rolling There is always a ball in the groove. For this reason, in order to prevent the ball from dropping off from the endless circulation path, it is necessary that the area of the screw shaft in which the ball rolling groove is formed is always covered with the nut member. In other words, the screw shaft can move in the axial direction of the nut member to be applied as long as the infinite circulation path does not protrude from the hollow portion of the nut member.

[0005] In the ball screw device disclosed in Japanese Patent Application Laid-Open No. 2003-222220, since the ball guide members for forming an infinite circulation path of the ball are provided at both ends of the screw shaft, the screw shaft is a nut. It is formed shorter than the full length of the member. For this reason, in order to input rotational motion to the screw shaft or to output linear motion from the screw shaft, the input / output shaft may be fixed to one or both ends of the screw shaft via the ball guide member. This is necessary, and the mounting strength of the input / output shaft relative to the screw shaft must be low. In other words, the powerful ball screw device can only be used for light load applications and cannot be used for heavy load applications where a large rotational torque needs to be input to the screw shaft. Means for solving the problem

[0006] The present invention has been made in view of such a problem, and an object of the present invention is to be able to continuously form the screw shaft longer than the entire axial length of the nut member. The purpose is to provide an on-axis circulating type rolling element screw device that can be used by inputting a large rotational torque.

[0007] The rolling element screw device of the present invention includes a nut member having a through hole and having a spiral nut-side rolling groove formed on the inner peripheral surface of the through hole, and passing through the through hole of the nut member. And a screw shaft having a shaft-side rolling groove facing the nut-side rolling groove formed on the outer peripheral surface, and the nut-side rolling groove and the shaft-side rolling groove are formed to face each other. It consists of a large number of rolling elements arranged in a load spiral path. Then, the rolling element is circulated on the screw shaft in an unloaded state from one end of the shaft side rolling groove to the other end, that is, from one end to the other end of the load spiral passage. A rolling element return passage is built in. Therefore, in this rolling element screw device, the screw shaft is provided with an infinite circulation path of the rolling element.

[0008] Further, the screw shaft has a hollow portion and is formed in a cylindrical shape, the shaft-side rolling groove is formed on an outer peripheral surface, and a pair corresponding to both ends of the shaft-side rolling groove. And a pair of rolling shafts formed in the screw shaft body. The screw shaft body has a rolling shaft pull-in hole formed in a peripheral wall, the screw shaft body includes the rolling body return passage, and is fixed in a hollow portion of the screw shaft body. It is comprised from the circulation path formation member which connects a moving body lead-in hole by a rolling element return path.

In such a rolling element screw device of the present invention, when the screw shaft is provided with an infinite circulation path of the rolling element, a pair of rolling element pull-in holes are formed in the peripheral wall of the cylindrically formed screw shaft main body. Since the pair of rolling element pull-in holes are connected via a circulation path forming member formed and fixed in the hollow portion of the screw shaft main body, the rolling element is circulated at both ends of the screw shaft main body. Therefore, it is possible to freely set the total length of the axial direction of the screw shaft body, which does not require any parts to be installed. That is, the total axial length of the screw shaft can be set longer than the total axial length of the nut member, and the rolling element screw device of the present invention can be used by inputting a large rotational torque to the screw shaft. It becomes possible.

[0010] Further, by forming the circulation path forming member fixed in the hollow portion of the screw shaft main body from a non-metallic material such as a resin material, ceramics, hydraulic composition, etc., the rolling element returns to the rolling element return passage. It is possible to suppress as much as possible the noise generated when rolling inside.

[0011] If the circulation path forming member is fixed in the hollow portion of the screw shaft main body and provides a rolling element return passage that becomes a part of the infinite circulation path of the rolling element, it has any shape. It does not matter if it is equipped. However, from the viewpoint of smoothly circulating the rolling element from the load spiral path formed between the screw shaft and the nut member to the rolling element return path in the screw shaft body, a powerful circulation path forming member is provided. Is preferably composed of a pair of inlet members mounted in the respective rolling element drawing holes, and a connecting member that connects the inlet members to form a rolling element return passage. In this case, the inlet member plays a role of guiding a rolling element that rolls along the outer peripheral surface of the screw shaft main body to the rolling element return passage through the rolling element pull-in hole.

[0012] The connecting member has any shape as long as it has a rolling element return passage! / ヽ There is no problem. For example, it may be formed in a cylindrical shape that fits tightly into the hollow portion of the screw shaft body, or may be fitted with a gap left in the hollow portion of the screw body. Absent. In the former case, the cylindrical connecting member itself is formed of the aforementioned non-metallic material. In the latter case, the aforementioned non-metallic material is applied to the hollow portion of the screw shaft body after the connecting member is fixed. By filling, vibration propagation in the screw shaft itself can be improved, and it is possible to obtain a rolling element screw device that generates less noise during use.

Brief Description of Drawings

FIG. 1 is a perspective view showing an embodiment of a ball screw device to which the present invention is applied.

2 is a perspective view showing a screw shaft of the ball screw device shown in FIG. 1. FIG.

FIG. 3 is a perspective view showing a screw shaft main body constituting the screw shaft.

FIG. 4 is a perspective view showing a circulation path forming member constituting a screw shaft.

FIG. 5 is a diagram schematically showing the infinite circulation path of the ball superimposed on the side view of the ball screw device.

FIG. 6 is a diagram schematically showing the infinite circulation path of the ball superimposed on the front view of the ball screw device.

FIG. 7 is a perspective view showing a screw shaft body in another example of a screw shaft.

FIG. 8 is a perspective view showing a circulation path forming member in another example of a screw shaft.

FIG. 9 is a perspective view showing an example of a circulation path forming member having a connecting member as a pipe body.

Explanation of symbols

[0014] 1 ... ball screw device, 2 ... nut member, 3 ... screw shaft, 4 ... ball, 30 ... shaft side rolling groove, 31 ... hollow part, 32 ... screw shaft body, 33 ... ... Circuit path forming member, 34 ... Rolling element lead-in hole, 40 ... Rolling element return passage

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an in-shaft circulation type rolling element screw device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example in which the present invention is applied to a ball screw device using balls as rolling elements. This ball screw device 1 is a nut having a through hole 20 and formed in a cylindrical shape. And a screw shaft 3 that is inserted into the through hole 20 of the nut member 2 and screwed into the nut member 2 via a large number of balls. The ball rolls while applying a load between the nut member 2 and the screw shaft 3, whereby the screw shaft 3 rotates in a spiral manner with respect to the nut member 2.

[0017] On the inner peripheral surface of the through hole 20 of the nut member 2, a rolling groove of the ball is formed in a spiral shape with a predetermined lead. The lead is the distance that the spiral rolling groove travels in the axial direction corresponding to one rotation of the screw shaft 3. In addition, a flange portion 21 is projected on the outer peripheral surface of the nut member 2, so that the nut member 2 can be fixed to various structures via a powerful flange portion 21! /, The

FIG. 2 is a perspective view showing a state in which the screw shaft 3 is taken out from the nut member 2. The screw shaft 3 is formed with a spiral rolling groove 30 on the outer peripheral surface. When the screw shaft 3 is inserted into the through hole 20 of the nut member 2, the shaft-side rolling groove 30 and the above-described rolling groove 30 are The nut-side rolling groove faces each other. That is, the shaft side rolling groove 30 is also formed of the same lead as the nut side rolling groove. In this way, the nut-side rolling groove and the shaft-side rolling groove 30 face each other, so that a load spiral path for rolling the ball 4 is formed between the nut member 2 and the screw shaft 3. The balls 4 are arranged in this load spiral path and roll while applying a load between the screw shaft 3 and the nut member 2.

On the other hand, the screw shaft 3 incorporates a rolling element return passage 40 for circulating the ball 4 from one end to the other end of the load spiral passage. After the ball 4 rolls in the load spiral path while applying a load, it is introduced into the rolling element return path 40 and becomes unloaded. After rolling the rolling element return path 40 in the unloaded condition, the ball 4 is loaded again. Return to the spiral path and load. As a result, the screw shaft 3 can be continuously rotated with respect to the nut member 2.

In order to provide the screw shaft 3 with the rolling element return passage 40, the screw shaft 3 includes a screw shaft main body 32 having a hollow portion 31 and formed in a cylindrical shape, and the rolling element return passage 40. In addition to this, a circulation path forming member 33 fixed in the hollow portion 31 of the screw shaft main body 32 is formed.

FIG. 3 is a perspective view showing the screw shaft main body 32. This screw shaft body 32 has an outer periphery The shaft side rolling groove 30 is formed in a spiral shape on the surface, and a pair of rolling element drawing holes 34, 34 are formed through the peripheral wall. Each rolling element pull-in hole 34 is formed so as to block the shaft side rolling groove 30, and each of them is provided at a position separated from the shaft side rolling groove 30 by several minutes. When the ball 4 rolled in the load spiral passage reaches one rolling element drawing hole 34, the ball 4 enters the inside of the screw shaft main body 33 from the rolling element drawing hole 34, and is provided in the circulation path forming member 33. It is introduced into the return passage 40. Further, the ball 4 rolling in the rolling element return passage 40 is fed out of the screw shaft main body 32 from the other rolling element pull-in hole 34 and introduced into the load spiral path.

FIG. 4 is an exploded perspective view showing the circulation path forming member 33. The circulation path forming member 33 is formed in a substantially cylindrical shape that fits into the pair of inlet members 35 and 35 attached to the rolling element drawing holes 34 of the screw shaft main body 32 and the hollow portion 31 of the screw shaft main body 32. The connecting member 36 and the force are also configured. A spiral groove 37 that functions as a rolling element return passage 40 is formed on the outer peripheral surface of the connecting member 36. The spiral groove 37 is formed between a pair of rolling element pull-in holes 34, 34 formed in the screw shaft body 32, and the direction of the heel is the shaft side rolling groove 30, that is, the heel of the load spiral passage. The direction is opposite. When the connecting member 36 formed in a cylindrical shape is closely fitted and fixed in the hollow portion 31 of the screw shaft main body 32, the spiral groove 37 is covered with the screw shaft main body 32, and the screw shaft main body 32 and the connecting member 36 are fixed. Between them, the rolling element return passage 40 is completed. The groove width and depth of the spiral groove 37 are set to be slightly larger than the diameter of the ball 4, so that the ball 4 rolls inside the rolling element return passage 40 in an unloaded state. Is possible.

[0023] The inlet member 35 is mounted in the rolling element retracting hole 34 of the screw shaft main body 32, and guides the ball 4 that has rolled in the load spiral path from the rolling element retracting hole 34 to the rolling element return path 40. It has a function to do. The inlet member 35 is formed with a guide groove 38 for smoothly connecting the shaft-side rolling groove 30 and the rolling element return path 40, and the ball 4 is loaded to the rolling element pull-in hole 34. A guiding lip 39 is provided. The lip 39 is provided so as to cover the guide groove 38, and the outer peripheral surface force of the screw shaft 3 protrudes into the nut-side rolling groove. As a result, the ball 4 that rolls in the load spiral path and reaches the opening position of the rolling element drawing hole 34 is guided to the lip 39. Then, it enters the guide groove 38 of the inlet member 35, is released from the load, and is introduced into the rolling element return passage 40.

[0024] The inlet member 35 and the connecting member 36 can be molded using a non-metallic material such as a synthetic resin or a hydraulic composition. Thereby, generation | occurrence | production of the noise at the time of the ball 4 entering / exiting the rolling element return path 40 from a load spiral path can be suppressed as much as possible. Further, by tightly fitting the connecting member 36 formed of a non-metallic material to the hollow portion 31 of the screw shaft main body 32, when the ball 4 rolls in the shaft side rolling groove 30, the screw shaft The effect of dampening the vibration generated in Fig. 3 is demonstrated, and a ball screw device that suppresses the generation of noise during use can be obtained.

In the screw shaft main body 32 shown in FIG. 3, the hollow portion 31 is formed as a through hole. However, the hollow portion 31 may be closed at one end.

FIG. 5 and FIG. 6 show the circulation path of the ball 4 in the ball screw device 1 in a side view and a front view of the ball screw device. The load spiral passage 41 is drawn with a one-dot chain line, and the rolling element return passage 40 is drawn with a broken line. The ball 4 rolls between the nut member 2 and the screw shaft 3 in a load spiral path 41 drawn by a one-dot chain line, whereby the nut member 2 rotates in a spiral manner with respect to the screw shaft 3. It is possible. In addition, the ball 4 that has rolled on the load spiral passage 41 and reached the inlet member 35 attached to the screw shaft 3 is inserted into the screw shaft 3 from the rolling element drawing hole 34 by the lip 39 of the inlet member 35. It is introduced into the rolling element return passage 40 and rolls in a no-load state in the rolling element return passage 40 drawn by a broken line. Then, at the end of the rolling element return passage 40, this time it is guided out of the screw shaft 3 from the rolling element pull-in hole 34, and is again fed into the load spiral passage 41 drawn by a one-dot chain line. Therefore, when the nut member 2 and the screw shaft 3 rotate relatively, the ball 4 circulates repeatedly through the above path.

Accordingly, the nut member 2 can be linearly moved in the axial direction of the screw shaft 3 by inputting the rotational motion to the screw shaft 3, and the screw shaft can be obtained by inputting the rotational motion to the nut member 2. 3 can be moved linearly in the axial direction. However, if the inlet member 35 jumps out of the through hole 20 of the nut member 2 as a result of the relative movement between the screw shaft 3 and the nut member 2, a part of the shaft-side rolling groove 30 is part of the nut. Load spiral passage that no longer faces the side rolling groove A part of 41 disappears, and the balls 4 arranged in the shaft-side rolling groove 30 roll off. That is, in the ball screw device of the present invention, the nut member 2 cannot move infinitely along the screw shaft 3, and the nut member 2 is axially moved with respect to the screw shaft 3 only within a predetermined range. It can move to.

[0028] Then, in the ball screw device 1 configured as described above, when the ball 4 is moved in and out of the rolling element return passage 40 built in the screw shaft 3, the force is applied to the shaft end of the screw shaft 3 that exerts force. It is possible to set the overall length in the axial direction of the screw shaft 3 to be larger than the overall length in the axial direction of the nut member 2 without having to fix any parts for circulating the balls 4. Therefore, the motor can be directly coupled to the shaft end of the screw shaft 3, and the ball screw device 1 can be used by inputting a large rotational torque to the screw shaft 3. .

[0029] Further, the rolling element return passage 40 is formed in the hollow portion 31 of the screw shaft main body 32, and the region of the screw shaft 3 in which the rolling element return passage 40 is further formed is always covered by the nut member 2. Therefore, the noise generated by the rolling of the ball 4 in the rolling element return passage 40 leaks out of the ball screw device 1 1, and the environment-friendly ball screw device 1 can be provided.

FIG. 7 and FIG. 8 show another example of the screw shaft, FIG. 7 shows the screw shaft main body 5, and FIG. 8 shows the circulation path forming member 6. In the example of the screw shaft 2 shown in FIG. 2, the force that formed the rolling element return passage 40 spirally in the screw shaft 2 In the examples shown in FIGS. 7 and 8, the rolling element return passage 42 is connected to the screw shaft. It is formed along the axial direction of the main body 5.

As shown in FIG. 7, the screw shaft main body 5 has a hollow portion 50 and is formed in a cylindrical shape, and a shaft-side rolling groove 51 opposed to the nut-side rolling groove on the outer peripheral surface thereof. Is formed in a spiral shape. In addition, a pair of rolling element drawing holes 52, 52 are formed in a slit shape along the circumferential direction on the peripheral wall of the screw shaft body 5, and the shaft side rolling groove 51 is blocked by the rolling element drawing holes 52. Yes.

[0032] On the other hand, the circulation path forming member 6 includes a pair of inlet members 60, 60 mounted in the rolling element drawing holes 52, and the screw shaft main body 5 so as to connect the inlet members 60, 60 to each other. The connecting member 61 is fixed in the hollow portion 50. The inlet member 60 has a curved surface that follows the outer peripheral surface of the screw shaft body 5 and is formed in a substantially semicircular shape. It is fixed to the screw shaft body 5 so as to close the hole 52. Each inlet member 60 is formed with a guide hole 62 for feeding the ball 4 that has been rolling along the load spiral path into the rolling element return path 42.

The connecting member 61 is formed in a substantially rectangular shape, and is inserted into and fitted into the hollow portion 50 of the screw shaft main body 5 from the shaft end of the screw shaft main body 5, and a pair of inlets By being sandwiched between the members 60 mm, they are fixed in the hollow portion 50 of the screw shaft main body 5. A rolling element return passage 42 is formed in the connecting member 61 along the axial direction of the screw shaft body 5, and the rolling element return passage 42 curves gently toward the inlet member 60 at both ends thereof. It is connected to the guide hole 62 of the powerful inlet member 60. That is, the rolling element return passage 42 and the load spiral passage are connected through the guide hole 62 of the inlet member 60, and the infinite circulation path of the ball 4 is completed. The inner diameter of the guide hole 62 and the rolling element return passage 42 is formed larger than the diameter of the ball 4, and the ball 4 rolls in an unloaded state in the guide hole 62 and the rolling element return passage 42.

[0034] The inlet member 60 and the connecting member 61 can be molded using a non-metallic material such as a synthetic resin or a hydraulic composition. As a result, it is possible to suppress as much as possible the generation of noise when the ball 4 enters and exits the load spiral passage force rolling element return passage 40. In addition, after fixing the inlet member 60 and the connecting member 61 to the screw shaft main body 5, a synthetic resin or a hydraulic composition is poured into the hollow portion 50 of the screw shaft main body 5, and the connecting member 61 and the screw shaft main body 5 By filling these gaps with these, the generation of noise can be further reduced.

[0035] If the connecting member 61 is provided with the rolling element return passage 42 that is not necessarily rectangular, the connecting member 61 spans between a pair of inlet members 60 as shown in FIG. 9, for example. Even the pipe body 63 to be used can be used. The pair of inlet members 60 may be formed integrally with the connecting member 61.

[0036] Even when the screw shaft configured as shown in Figs. 7 and 8 is used, the total axial length of the screw shaft is set larger than the total axial length of the nut member 2. It is possible to connect the motor directly to the shaft end of the screw shaft, and it is possible to use this ball screw device by inputting a large rotational torque to the screw shaft. In the example described above, even when a force roller using a ball is used as a rolling element, the same configuration can be used.

Claims

The scope of the claims

[1] A nut member (2) having a through hole (20) and having a spiral nut-side rolling groove formed on the inner peripheral surface of the through hole, and being passed through the through hole of the nut member The screw shaft (3) having a shaft-side rolling groove (30) facing the nut-side rolling groove formed on the outer peripheral surface, and the nut-side rolling groove and the shaft-side rolling groove (30) face each other. Consisting of a large number of rolling elements (4) arranged in a load spiral path formed by

The screw shaft (3) has a rolling element return passage (40) for circulating the rolling element from one end to the other end of the shaft side rolling groove (30), that is, one end force of the load spiral passage to the other end in an unloaded state. In-shaft circulating rolling element screw device (1) with built-in! /,

The screw shaft (3) has a hollow portion (31) and is formed in a cylindrical shape, the shaft-side rolling groove (30) is formed on the outer peripheral surface, and the shaft-side rolling groove is further formed at both ends of the shaft-side rolling groove. Correspondingly, the screw shaft main body (32) having a pair of rolling element drawing holes (34) formed through the peripheral wall, the rolling element return passage (40), and the screw shaft main body (32) are hollow. A circulation path forming member (33) that is fixed in the section and connects a pair of rolling element drawing holes (34) formed in the screw shaft main body (32) with a rolling element return path (40). An in-shaft circulation type rolling element screw device.

[2] The on-axis circulation type rolling element screw device according to [1], wherein the circulation path forming member (33) is also formed with a non-metallic material force.

[3] The circulation path forming member (33) is mounted in each rolling element drawing hole (34) of the screw shaft body (32), and the rolling element (4) in the load spiral path is connected to the rolling element return path ( 40), a pair of inlet members (35), and a connecting member (36) that includes the rolling element return passage (40) and connects the inlet members to each other. The in-shaft circulating rolling element screw device according to claim 1.

[4] The connecting member (36) is formed in a cylindrical shape that fits tightly into the hollow portion of the screw shaft main body (32), and the rolling element return passage (40) is axially rolled on the outer peripheral surface thereof. The in-shaft circulation type rolling element screw device according to claim 3, wherein the screw device is formed as a spiral groove in a direction opposite to the groove (30).

[5] A space is formed between the coupling member (36) and the inner peripheral surface of the screw shaft body (32), and the space is filled with a nonmetallic material. In-shaft circulation according to claim 3 Type rolling element screw device.

The inlet member (35) is present in the gap between the screw shaft (3) and the nut member (2) and closes the end of the load spiral path, and the rolling element (4) is inserted into the rolling element drawing hole (34). 4. The in-shaft circulation type rolling element screw device according to claim 3, further comprising a lip (39) for guiding to the shaft.