WO2008065958A1

WO2008065958A1 - Movement guiding device and method of producing the same

Info

Publication number: WO2008065958A1
Application number: PCT/JP2007/072633
Authority: WO
Inventors: Hiroaki Mochizuki
Original assignee: Thk Co., Ltd.
Priority date: 2006-11-30
Filing date: 2007-11-22
Publication date: 2008-06-05

Abstract

A movement guiding device in which, even if the center of a raceway shaft is tilted relative to the center of a housing, load acting on rolling bodies arranged in the axial direction is equalized. The movement guiding device has the raceway shaft (1), an outer tube (2) assembled to the raceway shaft (1) so as to be movable in the axial direction and having provided in it a rolling body circulation route including an axially extending groove in which loaded rolling bodies roll, and rolling bodies (4) arranged in the rolling body circulation route. The outer tube (2) has a body (5) having in its inner surface the above groove in which loaded rolling bodies roll, an outer shell (10) placed on the outer side of the body (5), and a soft section (9) placed between the outer shell (10) and the body (5) and having lower rigidity than the outer shell (10) and the body (5). Even if the outer shell (10) tilts, the soft section (9) deforms, so that the body (5) tilts less than the outer shell (10). As a result, load on the axially arranged rolling bodies (4) is equalized.

Description

Specification

Motion guide device and manufacturing method thereof

Technical field

The present invention relates to a motion guide device such as a ball bush or a ball spline in which a rolling element such as a ball is interposed between a raceway shaft and an outer cylinder that is assembled to the raceway shaft so as to be capable of relative motion.

Background art

[0002] The ball bushing and ball spline are motion guide devices that guide the linear movement of the moving body relative to the fixed side even when! / Is displaced, and is attached to either the fixed side or the moving body A track shaft and an outer cylinder attached to the other. A ball circulation path for circulating the ball is provided in the outer cylinder mounted on the fixed side or the housing of the moving body. The ball circulation path includes a ball rolling groove extending in the axial direction formed on the inner surface of the outer cylinder. A plurality of balls are arranged in the ball circulation path. Along with the linear movement of the outer cylinder relative to the raceway axis, a plurality of balls move in a rolling force while receiving a load between the ball rolling groove on the inner face of the outer cylinder and the outer face of the raceway axis.

[0003] The ball bushing has a cylindrical raceway shaft, and the ball and the surface of the raceway shaft are in point contact. For this reason, although the allowable load is small, it becomes a light exercise plan device that moves linearly with the minimum frictional resistance. On the other hand, in the ball spline, the raceway shaft is a spline shaft, and a ball rolling groove facing the ball rolling groove of the outer cylinder is machined on the outer surface of the raceway shaft. If the ball rolling groove is machined on the raceway shaft, the contact area between the ball rolling groove of the raceway shaft and the ball can be increased, so that a large load capacity can be provided in the radial direction and the torque direction.

[0004] The outer cylinder of the ball bushing is attached to one housing of the fixed side or the moving body, and the track shaft is supported by the other of the moving body or the fixed side. If the center of the housing coincides with the center of the track shaft, the clearance between the ball rolling groove on the inner surface of the outer cylinder and the outer surface of the track shaft will not change in the axial direction of the track shaft. Therefore, the load applied to the plurality of balls arranged in the axial direction of the track axis is also constant, and the balls smoothly roll in the ball rolling grooves. However, the center of the housing and the center of the track axis do not coincide (ie, the center is aligned. If this is not the case, the clearance between the ball rolling groove on the inner surface of the outer cylinder and the outer surface of the track shaft will change in the axial direction of the track shaft. Therefore, the load applied to the ball also changes depending on the position of the ball in the axial direction of the track axis, the largest load is applied to the ball at one end in the axial direction, and the load force S is not applied to the ball at the other end in the axial direction. . If the load on multiple balls is unbalanced, the life of the ball will be shortened and the load received by the entire ball will be reduced.

[0005] In order to solve this problem, there has been proposed a self-aligning ball bush that makes it difficult for the center of the outer cylinder to deviate from the center of the track axis even if the center of the housing and the center of the track axis shift. (For example, see Patent Document 1). In this self-aligning ball bushing, as shown in FIG. 14, a load receiving plate 51 is provided at a specific location in the circumferential direction of the outer cylinder. An intermediate thick portion 51b is formed on the load receiving plate 51, and a ball rolling groove 51a on which the ball 52 rolls is formed on the inner surface of the load receiving plate 51. A concave portion is provided on the outer surface of the load receiving plate 51, and a strip 53 made of an elastomer material is inserted into the concave portion.

[0006] When the center of the housing 54 is inclined with respect to the center of the track shaft 55, the load receiving plate 51 is tilted with respect to the housing 54 with the intermediate thick portion 51b as a fulcrum and parallel to the track shaft 55. Become. Therefore, it is possible to prevent an excessive load force S from being applied to some of the plurality of balls 52 arranged in the axial direction. Further, when the load receiving plate 51 is inclined, the elastomer material is compressed and deformed, so that the static rigidity of the ball bushing is also increased.

Patent Document 1: Japanese Patent Publication No. 58-27406 (refer to page 1, Fig. 3)

Disclosure of the invention

Problems to be solved by the invention

[0007] In the conventional self-aligning ball bushing, when the inclination angle of the center of the track shaft 55 with respect to the center of the housing 54 is less than a predetermined angle (for example, less than 0.5 degrees), the load receiving plate 51 It can tilt following axis 55. However, if the tilt angle exceeds a predetermined angle, the load receiving plate 51 cannot follow the track shaft 55, and an excessive load is applied to the ball 52 on one end side of the plurality of balls 52 arranged in the axial direction. This is because the elastomer material is only used to restore the inclined load receiving plate 51 parallel to the center of the housing 54, and the load applied to the ball 52 depends solely on the inclination angle of the load receiving plate 51. Because. [0008] Even if the center of the housing 54 and the center of the track shaft 55 are not initially shifted, if the moment load in the pitching direction is applied to the ball bush, the center of the track shaft 55 is tilted with respect to the center of the housing 54. Thus, an excessive load is applied to the ball 52 on one end side among the plurality of balls 52 arranged in the axial direction. When an excessive load is applied to the ball 52, a flaking phenomenon (a phenomenon in which a part of the ball 52 is peeled off) occurs. Since the allowable value for the moment in the pitching direction is determined so that an excessive load is not applied to the ball 52 on one end, the allowable value for the moment in the pitching direction is limited.

[0009] Therefore, the present invention can equalize the force and load applied to the rolling elements arranged in the axial direction even if the center of the track axis is inclined with respect to the center of the housing, thereby increasing the allowable value of moment in the pitching direction. It is an object of the present invention to provide a motion guide device and a method of manufacturing the same that can increase the allowable inclination angle of the center of the track axis with respect to the center of the housing.

Means for solving the problem

[0010] Hereinafter, the present invention will be described.

In order to solve the above-mentioned problems, the invention according to claim 1 is a rolling body circulation path including a raceway shaft, a load rolling body rolling groove that is assembled to the raceway shaft so as to be movable in the axial direction and extends in the axial direction. And a plurality of rolling elements arranged in the rolling element circulation path, wherein the outer cylinder has an inner surface on which the rolling elements move by rolling force. A body portion having a groove; an outer shell portion disposed outside the body portion; and a soft material that is interposed between the outer shell portion and the body portion and has lower rigidity than the outer shell portion and the body portion. A motion guide device.

[0011] The invention according to claim 2 is the motion guide apparatus according to claim 1, wherein the outer shell portion has a protrusion protruding outward on an outer surface.

[0012] The invention according to claim 3 is the motion guide device according to claim 1 or 2, wherein the track shaft is disposed on an outer peripheral surface thereof, and is opposed to the load rolling element rolling groove of the main body. It has a rolling element rolling groove that extends in the direction and in which the rolling element rolls.

[0013] The invention according to claim 4 is the motion guide apparatus according to any one of claims 1 to 3, wherein the soft portion is an elastomer material bonded to the outer shell portion and the main body portion. It is characterized by comprising.

[0014] The invention according to claim 5 is the movement guide device according to claim 2, wherein the protrusion is integrally processed with the same material as the outer shell.

[0015] The invention according to claim 6 is the movement guide device according to any one of claims 1 to 5, wherein the main body is substantially cylindrical so as to surround the periphery of the track axis, The soft part and the outer shell part are substantially cylindrical so as to surround the periphery of the main body part, and are divided into a plurality of parts in the circumferential direction by a gap extending in the axial direction.

[0016] The invention according to claim 7 is the motion guide apparatus according to any one of claims 1 to 6, wherein a plurality of the outer cylinders are provided in an axial direction of the track axis.

The invention according to claim 8 is an outer cylinder provided with a raceway shaft and a rolling element circulation path including a load rolling element rolling groove that is assembled to the raceway axis so as to be movable in the axial direction and extends in the axial direction. And a plurality of rolling elements arranged in the rolling element circulation path, and a method of manufacturing the outer cylinder of the motion guide device, the main body having the load rolling element rolling groove on the inner surface for rolling the rolling element A main body processing step for processing a portion, and an outer shell is disposed outside the main body, and is less rigid than the outer shell and the main body between the outer shell and the main body. A method for manufacturing a motion guide device comprising: a soft part interposing step for interposing a soft part.

[0018] The invention according to claim 9 is the method of manufacturing the motion guide device according to claim 8, wherein in the soft part interposing step, the soft part is interposed between the main body part and the outer shell part. The elastomer material is vulcanized and bonded.

The invention's effect

[0019] According to the invention described in claim 1, since the soft portion is interposed between the outer shell portion and the main body portion, even if the outer shell portion is inclined, the soft portion is deformed and the main body portion is deformed. Does not tilt as much as the outer shell. Therefore, the load applied to the rolling elements arranged in the axial direction can be made uniform.

[0020] According to the invention of claim 2, the outer shell portion swings around the protrusion as a fulcrum, so the outer shell portion is easily inclined.

[0021] According to the invention described in claim 3, since the raceway shaft has the ball rolling groove on the outer peripheral surface, the ball rolling groove of the raceway shaft and the rolling element are not in point contact but in surface contact. Make surface contact As a result, the allowable load of the rolling elements can be increased, and the amount of elastic deformation of the rolling elements also increases. Therefore, the allowable inclination angle of the outer shell portion can be further increased.

[0022] According to the invention of claim 4, the soft part can be easily bonded to the outer shell part and the main body part, and the soft part can be easily deformed.

[0023] According to the invention described in claim 5, when the outer cylinder is fitted in the housing, it is possible to prevent the protrusion from coming off the outer shell. In addition, protrusions can be easily formed on the outer shell.

[0024] According to the invention of claim 6, since the soft portion and the outer shell portion are divided into a plurality of portions in the circumferential direction, when the center of the outer cylinder is inclined with respect to the center of the housing, the soft portion and the outer shell portion are divided. The outer shell segment tilts without being affected by other segments, and the divided soft segment deforms without being affected by other segments. Therefore, the inclination angle of the center of the outer cylinder with respect to the center of the housing can be increased.

[0025] According to the invention of claim 7, by providing a plurality of outer cylinders in the axial direction of the track axis, the allowable load of moment in the pitching direction can be increased.

[0026] According to the invention of claim 8, since the soft portion is interposed between the outer shell portion and the main body portion, even if the outer shell portion is inclined, the soft portion is deformed and the main body portion is deformed. Does not tilt as much as the outer shell. Therefore, the load applied to the rolling elements arranged in the axial direction can be made uniform.

[0027] According to the invention of claim 9, the soft part can be easily bonded to the outer shell part and the main body part, and the soft part can be easily deformed.

Brief Description of Drawings

FIG. 1 is a perspective view of a ball spline according to a first embodiment of the present invention.

[Fig.2] Exploded perspective view of the above ball spline

[Figure 3] Side view of the above ball spline (including a partial cross-sectional view along the axial direction)

[Fig.4] Diagram showing the ball spline mounted on the housing

[Fig.5] Perspective view showing another example of a ball spline (example of two outer cylinders assembled to the raceway shaft)

[Fig. 6] Diagram showing a state in which a ball spline with two outer cylinders mounted on the track shaft is mounted on the housing FIG. 7 is a perspective view (including a partial cross-sectional view) of a ball bush according to a second embodiment of the present invention.

[Fig. 8] Side view of the above ball bush (including a partial cross-sectional view along the axial direction)

[Fig. 9] Front view of the ball bush (including a cross-sectional view perpendicular to the axial direction)

FIG. 10 is a side view of a ball bush according to a third embodiment of the present invention (including a sectional view partially along the axial direction).

[Fig. 11] Front view of the above ball bush (including a cross-sectional view perpendicular to the axial direction)

[Fig.12] Side view of bearing plate installed in the above ball bushing

[Fig. 13] Side view of another example of bearing plate

[Fig. 14] Side view of a conventional self-aligning ball bushing load receiving plate

Explanation of symbols

[0029] la… Ball rolling groove (rolling element rolling groove)

I, 21, 31 ... orbital axis

2, 22, 32 ... outer cylinder

3, 23 ··· Ball circulation path (Rolling body circulation path)

4, 24, 34… Bonore

5a, 25a, 38a… Loaded ball rolling groove (Loaded rolling element rolling groove)

5, 25, 38 ... Body

9, 29, 39… Rubber layer (soft part)

10, 30, 40 ... outer shell

10a, 30a, 40a ... protrusions

I I, 31… clearance

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a ball spline according to a first embodiment of the present invention. Fig. 1 shows an external perspective view of the ball spline, Fig. 2 shows an exploded perspective view, and Fig. 3 shows a side view (including a sectional view partially along the axial direction).

[0031] The ball spline is assembled with a raceway shaft 1 in which a ball rolling groove la in which a ball as a rolling element rolls is formed in the longitudinal direction, and the raceway shaft 1 so as to be relatively linearly movable in the axial direction. The outer cylinder 2 is provided. As shown in FIG. 2, the outer cylinder 2 is provided with a circuit-shaped ball circulation path 3. A plurality of balls 4 are arranged in the ball circulation path 3. The linear motion of the outer cylinder 2 with respect to the track shaft 1 is relative, and either the track shaft 1 or the outer tube 2 is attached to the moving body and the rest is attached to the fixed side.

[0032] The track shaft 1 is formed of a solid round bar or a hollow round bar. A plurality of (six in this embodiment) ball rolling grooves la extending in the axial direction are formed on the outer surface of the track shaft 1 so as to sandwich a plurality (three in this embodiment) of protrusions lb. . The cross-sectional shape of the ball rolling groove la is formed into a circular arc groove shape that is slightly larger than the curvature of the ball 4. Since the ball 4 rolls and rolls in the ball rolling groove la of the track shaft 1 while receiving a load, the hardness, surface roughness, and dimensional accuracy of the track shaft 1 are manufactured with care. The material of the raceway shaft 1 is preferably a material suitable for quenching such as bearing steel and carbon tool steel. Further, the surface of the ball rolling groove la of the track shaft 1 is processed to a predetermined hardness through a heat treatment such as quenching. In order to reduce the surface roughness of the ball rolling groove la, the outer peripheral surface of the ball rolling groove la is ground.

[0033] The outer cylinder 2 has a load ball rolling groove 5a (Fig.

3) and a holding member 6 incorporated inside the main body 5.

[0034] The main body 5 is a hollow cylinder. The outer peripheral surface of the main body 5 has a cylindrical shape, and the inner peripheral surface of the main body 5 has an irregular shape that repeatedly includes a large diameter portion and a small diameter portion. A loaded ball rolling groove 5a extending in the axial direction is formed in the inner diameter portion. A plurality of load ball rolling grooves 5 a are provided corresponding to the ball rolling grooves 1 a of the raceway shaft 1.

[0035] The main body 5 is manufactured, for example, by processing a material into an irregular shape by extrusion molding or the like, cutting an inner diameter / outer shape 'end face, etc., and quenching and grinding the outer diameter / inner diameter. The material of the main body 5 is preferably a material suitable for quenching such as bearing steel and carbon tool steel. From the viewpoint of reducing manufacturing costs, the outer diameter of the main body may not be ground.

[0036] The ball 4 is made of steel in the same manner as a rolling element used for a general bearing.

As shown in FIG. 2, a holding member 6 is incorporated in the main body 5. The holding member 6 is a hollow cylinder incorporated inside the main body 5. The outer peripheral surface of the holding member 6 It is an irregular shape with a shape matched to the peripheral surface, and has a large diameter portion and a small diameter portion. In the holding member 6, a plurality of circuit-like ball circulation paths 3 are formed in accordance with the number of the loaded ball rolling grooves 5 a of the main body 5. The ball circulation path 3 includes a load ball rolling path 3a along the load ball rolling groove 5a of the main body 5, a ball return path 3b extending in parallel with the load ball rolling path 3a, and an end of the load ball rolling path 3a and the ball return. It consists of an arc-shaped direction change path 3c that connects the end of the path 3b. The load ball rolling path 3a is in the small diameter portion of the holding member 6, and the ball 4 is in contact with the load ball rolling groove 5a of the main body 5 and the ball rolling groove la of the track shaft 1 so that it can roll. The holding member 6 opens on both the outer peripheral surface and the inner peripheral surface. On the other hand, the ball return passage 3b is in the large-diameter portion of the holding member 6 and opens only on the outer peripheral surface of the holding member 6. The holding member 6 holds the row of balls arranged and accommodated in the ball circulation path 3 in a circulatory manner, and prevents the balls 4 from falling off when the main body 5 is removed from the track shaft 1. The holding member 6 is fixed to a predetermined position of the main body by a retaining ring 8.

As shown in FIG. 1, an outer shell portion 10 is disposed outside the main body portion 5. The outer shell portion 10 has a cylindrical shape and is shorter in the axial direction than the main body portion 5. A projection 10a protruding in a ring shape is provided on the outer side in the radial direction at the center of the outer surface of the outer shell 10 in the axial direction. The cross section of the protrusion 10a is semicircular. The outer shell 10 is divided into a plurality (four in this embodiment) in the circumferential direction by a gap 11 extending in the axial direction.

[0039] The outer shell portion 10 is made of, for example, metal including the protrusion 10a, and is manufactured by press molding. If the protrusion 10a is made of metal, the coefficient of friction is small, so the outer cylinder 2 can be easily inserted into the insertion hole of the housing. Further, when the protrusion 10a is made of metal, the protrusion 10a is crushed when a radial load or a moment load force S is applied to the outer cylinder 2. Therefore, a space can be maintained around the protrusion 10a and the outer shell portion 10 can be allowed to tilt. The protrusion 10a may be a rubber ring and wound around the outer shell portion 10.

[0040] The protrusion 10a is not limited to being provided at the axially central portion of the outer surface of the outer shell portion 10. For example, it may be formed in an arc shape that reaches the entire length of the outer surface in the axial direction (see FIG. 12), or may be provided at a position deviated from the center in the axial direction. The cross-sectional shape of the protrusion 10a is not limited to the arc shape, and may be formed in a mountain-like shape with a wide base (see FIG. 13). In short, with the radial load force S applied, the projection 10a is supported. It is only necessary that the outer shell 10 can be tilted with respect to the housing.

[0041] Between the outer shell portion 10 and the main body portion 5, a rubber layer 9 as a soft portion is interposed. The rubber layer 9 is made of an elastomer material and is bonded to the outer shell portion 10 and the main body portion 5. The shape of the rubber layer 9 is a cylindrical shape surrounding the periphery of the main body portion 5 and is divided into a plurality of portions in the circumferential direction by a gap 11 extending in the axial direction like the outer shell portion 10!

[0042] For bonding the main body 5 and the outer shell 10 to the rubber layer 9, bonding using an adhesive or vulcanization bonding that bonds simultaneously with rubber molding is used. When vulcanizing and bonding, an adhesive is applied to the outer peripheral surface of the main body portion 5 and the inner peripheral surface of the outer shell portion 10, and these are placed in a mold. After that, a rubber compound is injected between the main body part 5 and the outer shell part 10 (note that the injection hole for injecting the rubber compound is opened in the outer shell part. The pressure is increased between the outer shell part 10 and the main body part 5 to increase the temperature. When a predetermined time has passed, the rubber is press vulcanized, and the rubber layer 9 is vulcanized and bonded to the main body 5 and the outer shell 10. After the rubber molding, the outer cylinder 2 is removed from the mold.

[0043] A method for assembling the ball spline will be described. First, the outer shell portion 10 is disposed around the main body portion 5, and the main body portion 5 and the outer shell portion 10 are bonded together by the rubber layer 9. Next, with the plurality of balls 4 arranged in the circuit-shaped ball circulation path 3 of the holding member 6, the holding member 6 is combined with the deformed shape of the holding member 6 and the deformed shape of the main body portion 5 while being accommodated. Is inserted into the main unit 5. When retaining rings 8 elastically deformed are fitted to both ends of the main body 5, the holding member 6 is fixed to the main body 5. Finally, the outer cylinder 2 is mounted on the track shaft 1 so that the ball row fits into the ball rolling groove la.

[0044] When the main body 5 is linearly moved relative to the track axis 1, the ball 4 rolls in the axial direction while receiving a load on the load ball rolling path 3a. The ball 4 that has rolled to one end of the loaded ball rolling path 3a is scooped up into the direction changing path 3c of the holding member 6, changed direction, and moved to the ball return path 3b. In the ball return path 3b, the ball 4 moves while being pushed by the subsequent ball 4. The ball 4 that has moved to one end of the ball return path 3b is changed in direction by the other direction change path 3c and returned to the load ball rolling path 3a again.

FIG. 4 shows a state where the ball spline is mounted on the housing. Housing 13 A cylindrical hole 13a is opened. The outer cylinder 2 is inserted into the hole 13 a of the housing 13. The outer diameter of the outer cylinder 2 is slightly larger than the inner diameter of the hole 13a of the housing 13, and there is a tightening margin between the hole 13a of the housing 13 and the outer cylinder 2.

[0046] When a moment in the pitching direction is applied to the ball spline, or when there is a mounting error between the center of the housing 13 and the center of the track shaft, the center of the track shaft 1 is inclined with respect to the center of the housing 13. At this time, since the outer cylinder 2 is inclined so as to follow the track axis 1 with the protrusion 10a as a fulcrum, an excessive load is applied to some of the plurality of balls 4 arranged between the outer cylinder 2 and the track axis 1. There is no power. Since the outer shell 10 and the rubber layer 9 are divided into a plurality of segments in the circumferential direction, when the center of the outer cylinder is inclined with respect to the center of the housing 13, one segment of the outer shell 10 and the rubber layer 9 Leans unaffected by other segments.

When a larger moment in the pitching direction is applied to the ball spline, the center of the track axis 1 is more inclined with respect to the center of the housing 13 (inclination angle Θ). Since there is a limit to the inclination of the outer shell portion 10 following the track axis 1, an excessive load is applied to the ball 4a on one end side of the balls 4 arranged in the axial direction. At this time, since the rubber layer 9 interposed between the outer shell portion 10 and the main body portion 5 undergoes inertial deformation, the load applied to the ball 4a on one end side can be reduced, and a plurality of balls The load applied to 4 can be made uniform. Since the entire row of balls that are not part of the balls 4a receives the load, the allowable value of the moment in the pitching direction that can be loaded can be increased.

[0048] When the ball rolling groove la is formed on the outer peripheral surface of the raceway shaft 1, the ball contact groove la of the raceway shaft 1 and the ball 4 are brought into surface contact not in point contact. Therefore, the allowable load applied to one ball 4 can be increased, and the amount of elastic deformation of the ball 4 is increased. Therefore, it is possible to increase the allowable inclination angle of the track axis 1 more. Furthermore, by forming the ball rolling groove la on the outer peripheral surface of the raceway shaft 1, it becomes possible to prevent rotation, so there is no need to use the raceway shaft 1 side by side in parallel with the 2nd way like a ball bush. Axis 1 can be used as a single axis

FIG. 5 shows an example in which two outer cylinders 2 are assembled to the track shaft 1. When receiving a larger moment in the pitching direction, a plurality of outer cylinders 2 may be provided side by side in the axial direction of the track axis 1.

Yes FIG. 6 shows a state where a ball spline assembled with two outer cylinders 2 is inserted into a cylindrical hole of the housing 13. When a moment Mp in the pitching direction is applied, a radial load Fa acts on one outer cylinder 2 and a reverse radial load Fb acts on the other outer cylinder. If the span of the two outer cylinders 2 becomes longer, the radial load Fa and the reverse radial load Fb become smaller, and if the span becomes shorter, the radial load Fa and the reverse radial load Fb become larger. The two outer cylinders 2 are shifted in opposite directions by the radial load Fa and the reverse radial load Fb. The shift amount of the two outer cylinders 2 can be obtained from the radial spring constant of the outer cylinder 2. Since the two outer cylinders 2 are shifted in the same housing 13, the center of the track axis 1 is inclined with respect to the center of the housing 13. By interposing the rubber layer 9 in the outer cylinder 2, the alignment function can be improved and the allowable inclination angle of the track shaft 1 can be increased.

7 to 9 show a ball bush according to a second embodiment of the present invention. Fig. 7 shows a perspective view (including a partial cross-sectional view) of the ball bush, Fig. 8 shows a side view (including a partial cross-sectional view) of the ball bush, and Fig. 9 shows a front view in the axial direction of the ball bush ( Including a partial cross-sectional view). In the ball bush, the raceway shaft 21 has a cylindrical shape, and no ball rolling groove is formed. A plurality of balls 24 interposed between the track shaft 21 and the outer cylinder 22 so as to allow rolling motion are in point contact with the outer peripheral surface of the track shaft 21.

As shown in FIG. 7, the ball bush includes a raceway shaft 21 having an outer peripheral surface on which a ball 24 as a rolling element rolls, and an outer cylinder 22 assembled to the raceway shaft 21 so as to be relatively movable in the axial direction. And comprising. The outer cylinder 22 is provided with a circuit-shaped ball circulation path 23. A plurality of balls 24 are arranged in the ball circulation path 23.

[0053] The track shaft 21 is formed of a solid round bar or a hollow round bar. Since the ball 4 rolls directly on the outer peripheral surface of the cylindrical raceway shaft 21, the raceway shaft 21 is manufactured with attention to hardness, surface roughness, and dimensional accuracy. The material of the track shaft 21 is preferably a material suitable for quenching such as bearing steel and carbon tool steel, and the surface of the track shaft 21 is subjected to a heat treatment such as quenching to have a predetermined hardness. In order to reduce the surface roughness of the track shaft 21, the outer peripheral surface of the track shaft 21 may be ground.

The outer cylinder 22 has a main body portion 25 in which a load ball rolling groove 25a (see FIG. 9) extending in the axial direction is formed, and a holding member 26 incorporated inside the main body portion 25. [0055] The main body 25 is a hollow cylinder. As shown in FIG. 9, the outer peripheral surface of the main body 25 has a cylindrical shape, and the inner peripheral surface has an irregular shape in which a large diameter portion and a small diameter portion are repeated. A load ball rolling groove 25a extending in the axial direction is formed in the inner diameter portion of the irregular shape. The load ball rolling grooves 25a are formed, for example, in four strips at equal intervals in the circumferential direction.

[0056] The main body 25 is manufactured, for example, by processing a material into an irregular shape by extrusion molding or the like, cutting an inner diameter 'outer shape' end face, etc., and quenching, and then grinding the outer diameter and the inner diameter. The material of the main body 25 is preferably a material suitable for quenching such as bearing steel and carbon tool steel. The main body 25 may not be a complete cylindrical shape, but may be a so-called open shape cut in the axial direction. From the viewpoint of reducing manufacturing costs, the outer diameter grinding of the main body 25 may not be performed.

[0057] Inside the main body 25, a hollow cylindrical holding member 26 is incorporated. The outer peripheral surface of the holding member 26 has an irregular shape that matches the inner peripheral surface of the main body portion 25, and has a large diameter portion and a small diameter portion. Four circuit-like ball circulation paths 23 are formed in the holding member 26. The holding member 26 prevents the ball 24 from falling off when the main body 25 is removed from the track shaft 21.

An outer shell portion 30 is disposed outside the main body portion 25. The outer shell 30 has a cylindrical shape and is shorter in the axial direction than the main body 25. A protrusion 30a protruding in a ring shape is provided on the outer side in the radial direction at the center in the axial direction of the outer surface of the outer shell 30. The outer shell 30 is divided into a plurality (four in this embodiment) in the circumferential direction by gaps 31 (see FIG. 9) extending in the axial direction. The outer shell 30 is made of, for example, metal including the protrusions 30a, and is manufactured by press molding.

[0059] Between the outer shell portion 30 and the main body portion 25, a rubber layer 29 as a soft portion is interposed. The rubber layer 29 is made of an elastomer material and is vulcanized and bonded to the outer shell portion 30 and the main body portion 25. The shape of the rubber layer 29 is a cylindrical shape that surrounds the periphery of the main body portion 25, and is divided into a plurality of portions in the circumferential direction by a gap 31 that extends in the axial direction in the same manner as the outer shell portion 30! /.

[0060] A method of assembling the ball bush will be described. The ball 24 is arranged in the circuit-like borehole circulation path 23 of the holding member 26. To buy. In this state, book When retaining rings 27 that are elastically deformed are inserted into the circumferential grooves at both ends of the body part 25, the holding member 26 is fixed to the body part 25. Finally, the assembled outer cylinder 22 is fitted on the outer periphery of the track shaft 21.

[0061] According to the ball bush of this embodiment, since the rubber layer 29 is interposed between the outer shell portion 30 and the main body portion 25, the rubber layer 29 is deformed even if the outer shell portion 30 is inclined. The main body 25 does not tilt as much as the outer shell 30. Therefore, the load applied to the balls 24 arranged in the axial direction can be made uniform.

FIGS. 10 to 11 show a ball bush according to a third embodiment of the present invention. Fig. 10 shows a cross-sectional view along the axial direction of the ball bush, Fig. 11 shows a front view (including a partial cross-sectional view) seen from the axial direction of the ball bush, and Fig. 12 shows details of the bearing plate of the outer cylinder. The figure is shown. Also in the ball bush of this embodiment, the ball rolling groove is not formed in the track shaft 31 like the ball bush of the second embodiment, and the plurality of balls 34 and the track shaft 31 are dotted. Contact.

[0063] In the ball bush of this embodiment, the outer cylinder 32 includes a cylindrical resin frame 35 and a metal bearing plate 36 incorporated in a rectangular opening opened in the resin frame 35. Consists of Only the portion that receives the load of the outer cylinder 32 becomes the bearing plate 36. The reason why the outer cylinder 32 is composed of the resin frame 35 is to reduce the manufacturing cost and weight. The bearing plate 36 is insert-molded or fitted into the resin frame 35.

[0064] A hollow cylindrical holding member 37 is incorporated in the resin frame 35. In the holding member 37, for example, six circuit-like ball circulation paths are formed. The holding member 37 prevents the ball 34 from falling off when the outer cylinder 32 is removed from the track shaft 31.

[0065] As shown in FIG. 12, the bearing plate 36 includes a main body portion 38 in which a ball rolling groove 38a extending in the axial direction is formed, an outer shell portion 40 disposed outside the main body portion 38, and a main body. And a rubber layer 39 as a soft part interposed between the part 38 and the outer shell part 40. On the outer surface of the outer shell portion 40, an arc-shaped protrusion 40a protruding outward is formed. The rubber layer 39 is made of an elastomer material and is vulcanized and bonded to the outer shell portion 40 and the main body portion 38.

[0066] According to the ball bush of this embodiment, the outer shell portion 40 of the bearing plate 36 and the main body Since the rubber layer 39 is interposed between the portion 38 and the outer shell portion 40, the rubber layer 39 is deformed even if the outer shell portion 40 is inclined, and the main body portion 38 is not inclined as much as the outer shell portion 40. Therefore, the force and load applied to the balls 34 arranged in the axial direction can be made uniform.

When the bearing plate 36 is fitted into the resin frame 35, the bearing plate 36 swings with respect to the resin frame 35. It should be noted that the movement of the ball 34 deteriorates because the cross-sectional area of the passage where the transition from the loaded ball rolling path to the ball return path changes due to the swinging of the bearing plate 36.

FIG. 13 shows another example of the bearing plate. In the bearing plate 41 of this example, a protrusion 42a is provided at the axial center of the outer surface of the outer shell portion 42, and a rubber piece 43 extending in the axial direction is provided on the outer surface of the outer shell portion 42. The configuration of the main body portion 38 in which the ball rolling groove 38a is formed and the rubber layer 39 interposed between the main body portion 38 and the outer shell portion 42 are the same as the bearing plate shown in FIG. The explanation is omitted.

In the bearing plate 41 of this example, the protrusion 42 a of the outer shell portion 42 abuts on the cylindrical hole 13 a of the housing 13. The rubber piece 43 provided so as to avoid the protrusion 42a also contacts the hole 13a of the housing 13 and is compressed between the outer shell portion 42 and the hole 13a. When the bearing plate 41 is tilted! /, The rubber piece 43 is compressed and deformed. Therefore, it is necessary to increase the static rigidity of the ball bush.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the present invention can be applied to a V, finite stroke type motion guide device in which a ball as a rolling element does not circulate, and a roller type motion guide device using a roller instead of a ball as a rolling member. Can be applied to. Further, the outer surface of the outer shell portion may have a cylindrical shape where no protrusion is provided. Further, the outer shell and the rubber layer may not be divided by a gap extending in the axial direction.

[0071] This specification is based on Japanese Patent Application No. 2006-324902 filed on Nov. 30, 2006. All this content is included here.

Claims

The scope of the claims

[1] A track shaft, an outer cylinder that is assembled to the track shaft so as to be movable in the axial direction, and is provided with a rolling element circulation path including a load rolling element rolling groove that extends in the axial direction, and is arranged in the rolling element circulation path To the rolling element and the motion guide device provided!

The outer cylinder is

A main body having the rolling rolling element rolling groove on which the rolling element rolls on the inner surface; an outer shell disposed on the outer side of the main body;

A motion guide device including a soft part interposed between the outer shell part and the main body part and having lower rigidity than the outer shell part and the main body part.

2. The motion guide apparatus according to claim 1, wherein the outer shell portion has a protrusion protruding outward on an outer surface.

[3] The track shaft has, on the outer peripheral surface thereof, a rolling element rolling groove that extends in the axial direction so as to face the load rolling element rolling groove of the main body, and the rolling element moves. The motion guide device according to claim 1, wherein

4. The motion guide device according to any one of claims 1 to 3, wherein the soft portion is an elastomer material force bonded to the outer shell portion and the main body portion.

5. The motion guide device according to claim 2, wherein the protrusion is integrally processed with the same material as the outer shell portion.

[6] The main body is substantially cylindrical so as to surround the circumference of the track axis,

The soft part and the outer shell part are substantially cylindrical so as to surround the periphery of the main body part, and are divided into a plurality of parts in a circumferential direction by a gap extending in an axial direction. 1! /, And 5! /, The motion guidance device described in the gap.

7. The motion guide device according to claim 1, wherein a plurality of the outer cylinders are provided in the axial direction of the track axis.

[8] A track shaft, an outer cylinder that is assembled to the track shaft so as to be movable in the axial direction, and is provided with a rolling element circulation path including a load rolling element rolling groove that extends in the axial direction, and is arranged in the rolling element circulation path A plurality of rolling elements and a manufacturing method of the motion guide device provided,

A main body having the loaded rolling element rolling groove for rolling motion of the rolling element on the inner surface A body part processing step for processing the part

An outer shell is disposed outside the main body, and the outer shell and the main body are less rigid than the outer shell and the main body. And a method of manufacturing a motion guide device comprising the steps.

9. The exercise device according to claim 8, wherein in the soft part interposing step, an elastomer material as the soft part is vulcanized and bonded between the main body part and the outer shell part. Method.