JP3455608B2 - Spline unit and method of forming outer cylinder of spline unit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling contact type spline unit having rolling elements interposed between a spline shaft and an outer cylinder.

[0002]

2. Description of the Related Art A conventional spline unit of this type is
A cylindrical outer cylinder provided with a plurality of load ball rolling grooves on the inner circumference thereof is provided with a plurality of unloaded ball passages corresponding to the load ball rolling grooves. At both ends of the outer cylinder, side covers having a direction change path connecting the loaded ball rolling groove and the unloaded ball passage are attached. Further, a ball holding portion is provided on the inner circumference of the outer cylinder along the loaded ball rolling groove to prevent the balls from falling out of the loaded ball rolling groove.

A spline shaft is reciprocally inserted in the outer cylinder. A load ball rolling groove corresponding to the load ball rolling groove provided on the outer cylinder was provided on the outer periphery of the spline shaft, and a large number of balls were interposed between these load ball rolling grooves.

Conventionally, the ball holding portion, the side lid, and the unloaded ball passage that do not require high rigidity have been made of resin molded products to reduce the cost.

However, each of the above-mentioned conventional resin molding parts is a molded product separate from the outer cylinder, and an assembling process is required after molding separately.

Therefore, it is possible to reduce the number of assembling steps by integrally molding the ball holding portion and the outer cylinder.

As such an integral molding technique, for example, a linear motion ball bearing as shown in USP 4,128,279 is known.

As shown in FIG. 9, this linear motion ball bearing has an outer cylinder 10 with an open cross-section which is partially cut away.
1 and a shaft 105 inserted into the outer cylinder 101.

A large number of balls 104 arranged in the axial direction are interposed between the inner circumference of the outer cylinder 101 and the outer circumference of the shaft 105, and the outer cylinder 101 linearly moves along the shaft 105 via the balls 104. It is like this. Ball 104
A plurality of rows are provided in the circumferential direction of the outer cylinder 101, and each ball row is formed by the direction change path 108 and the outer cylinder 10 at both ends of the outer cylinder 101.
It circulates through a plurality of unloaded ball passages 110 provided on the outer peripheral side. Outer cylinder 101 and shaft 10
The balls 104 in the load range interposed between the balls 5 are held by ball holding portions 106 extending in the axial direction on both sides of the row of balls.

The ball holding portion 106, the inner peripheral portion 108a of the direction changing passage 108 and the unloaded ball passage 11 are provided.
No. 0 was integrally formed with the outer cylinder 101 by insert molding.

[0011]

However, in the case of the conventional linear motion ball bearing described above, when insert molding is performed, as shown in FIG. 1 mold 111, the outer cylinder 10
The inner periphery of 1 is brought into close contact with the second mold 112 to form the ball holding portion 106 and the cavities 106a and 110a for molding the unloaded ball passage 110.
There is a problem that it is difficult to bring the inner and outer circumferences of 01 into close contact with the first and second molds 111 and 112 accurately, and a gap is formed between the contact surfaces to cause burrs.

In particular, the inner circumference of the outer cylinder 101 and the second mold 112.
When burrs are generated between the contact surfaces with and, burrs are generated on the rolling surface of the loaded ball, and it is necessary to remove the burrs. However, it is very difficult and practically impossible to remove such burrs generated in the space between the ball holding portions 106, 106.

When such burrs are present, the ball 10
Since the circulation of No. 4 becomes worse, the feed accuracy becomes worse. In extreme cases, the balls 104 may be clogged and the machine may stop, which seriously affects productivity.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to accurately set the position of the resin portion formed on the outer cylinder and integrally mold the spline unit. Another object of the present invention is to provide a method for forming an outer cylinder of a spline unit.

[0015]

In order to achieve the above object, according to the present invention, a cylindrical outer cylinder having a plurality of load rolling element rolling grooves formed on its inner circumference, and an outer cylinder A plurality of unloaded rolling element passages corresponding to the loaded rolling element rolling grooves provided, and a direction change path that is provided at both ends of the outer cylinder and connects between the loaded rolling element rolling groove and the unloaded rolling element passage. A side lid provided, a rolling element holding portion that is provided along the load rolling element rolling groove to prevent the rolling element from falling out of the load rolling element rolling groove, and is inserted into the outer cylinder and is provided on the outer periphery with the A spline shaft provided with a load rolling element rolling groove corresponding to the load rolling element rolling groove provided on the outer cylinder; and a spline shaft interposed between the outer rolling element and the load rolling element rolling groove of the spline shaft. A spline unit equipped with a large number of rolling elements that endlessly circulate through a conversion path and an unloaded rolling element path. Te, the outer cylinder periphery, the load rolling element
After the grinding finish is performed based on the rolling groove, the outer cylinder
Is placed in the mold with reference to the load rolling element rolling groove.
By insert molding that the no-load rolling element passage, the rolling element holder and of the rolling element direction changing passage inner peripheral portion, characterized in that at least any one, formed integrally with the outer cylinder.

The load rolling element rolling grooves provided on the inner circumference of the outer cylinder are formed as a plurality of load rolling element groove sets in the circumferential direction, with a pair of load rolling element rolling grooves adjacent to each other as one set, and the spline is formed. The shaft has a plurality of corners located on the outer periphery between a pair of load rolling element rolling grooves forming each of the load rolling element rolling groove sets, and is provided on the outer cylinder on both side surfaces of the corners. It is preferable that a pair of load rolling element rolling grooves corresponding to the pair of load rolling element rolling grooves be provided.

The outer cylinder is formed of a resin in which a thin cylindrical core metal is embedded, and the inner peripheral surface of the core metal covered with the resin is partially exposed, and the exposed inner peripheral portion of the core metal is exposed. The load rolling element rolling groove is formed in the.

Further, the outer cylinder molding method is such that the outer circumference of the outer cylinder is
Perform grinding finish based on the rolling element rolling groove, and then
The outer cylinder, the load rolling grooves with respect to the placed in a mold, no-load rolling element passage, the rolling element holder and of the rolling element direction changing passage inner peripheral portion, at least any one Is integrally formed by insert molding.

[0019]

Further, the contact state between the rolling groove of the load rolling element and the mold allows a gap to the extent that the infiltration of the molding material can be prevented.

[0021]

According to the present invention, among the unloaded rolling element passage, the rolling element holding portion, and the inner circumferential portion of the rolling element direction change path, with reference to the loaded rolling element rolling groove provided on the inner circumference of the outer cylinder, At least one of them is integrally molded by insert molding.

As a result, the number of assembling steps can be reduced.

Further, there is no step due to an assembly error in the joint between the rolling element direction change path and the loaded rolling element rolling groove, and between the direction change path and the unloaded rolling element rolling groove, so that the rolling element can circulate smoothly. In addition, noise is reduced.

Since the outer cylinder is positioned in the mold with reference to the load rolling element rolling groove, burr between the load rolling element rolling groove and the die can be prevented.

If the outer periphery of the outer cylinder to be insert-molded is ground and finished with reference to the rolling groove of the load rolling element,
The gap between the outer circumference of the outer cylinder inserted in the mold and the contact surface between the mold can be set as small as possible, and the occurrence of burrs on the outer peripheral side can be prevented.

Here, in order to prevent burrs, it is not necessary that the contact surfaces of the outer cylinder and the mold are in close contact with each other, and even if there is a gap, the penetration of the molding material can be prevented. Any size will do. As in the present invention, the outer circumference is ground with reference to the load rolling element rolling groove, and the outer cylinder is arranged in the mold with reference to the load rolling element rolling groove. It can be set to a small fixed size that can prevent the inflow of molding material. Also, not only on the outer peripheral side of the outer cylinder,
Even between the load rolling element rolling groove on the inner peripheral side and the die, it is possible to set a small and constant size that can prevent the inflow of the molding material.

As described above, by setting the gap between the mold and the outer cylinder, the outer cylinder can be easily mounted and the occurrence of burrs can be prevented. If burr is generated in the rolling groove of the load rolling element, the burr cannot be removed, and the outer cylinder must be broken to remove the burr. Therefore, it is extremely important to prevent the generation of burrs.

In particular, if a slight gap is formed between the rolling groove of the load rolling element and the die so that the molding material can be prevented from entering, machining of the rolling groove of the load rolling element at the time of grinding and finishing. Accuracy requirements can be reduced.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows a spline unit according to the first embodiment of the present invention.

This spline unit 1 is schematically shown in FIG.
As shown in (a), it is composed of a cylindrical outer cylinder 3, a pair of side lids 5 provided at both ends of the outer cylinder 3, and a spline shaft 8 provided with a load ball rolling groove 7. There is.

As shown in FIGS. 2 to 4, the outer cylinder 3 is a highly rigid cylindrical body made of metal, and a plurality of load ball rolling grooves 2 are provided on the inner circumference thereof. The load ball rolling groove 2 is configured as a plurality of load ball rolling groove sets 2A in the circumferential direction with a pair of load ball rolling grooves 2 and 2 adjacent to each other as one set. In this embodiment, three sets of loaded ball rolling groove sets 2A are used.
Are evenly distributed in the circumferential direction.

On the other hand, the spline shaft 8 is inserted into the outer cylinder 4 and has a plurality of corner portions located on the outer periphery between the pair of load ball rolling grooves 2 and 2 forming each load ball rolling groove 2A group. 8a, and a pair of load ball rolling grooves 7, 7 corresponding to the pair of load ball rolling grooves 2, 2 provided on the outer cylinder 4 are provided on both side surfaces of the corner portion 8a. A ball 9 as a rolling element is interposed between the loaded ball rolling grooves 2 and 7 facing each other, and a predetermined preload is applied to the ball 9. As the rolling element, a roller or the like can be applied in addition to the ball. A contact angle line connecting the contact points of each load ball 9 with the load ball rolling grooves 2, 7 is inclined by a predetermined angle α with respect to a radial line connecting the center of the ball and the center of the spline shaft 8. This contact angle α is determined by the spline shaft 8
Are symmetrical to each other with respect to a line connecting the center of the corner and the center of the corner 8a.

The load ball rolling grooves 2 and 2 of each load ball rolling groove set 2A of the outer cylinder 3 are, as shown in FIGS. 2 (a) and 4 (c), a first U-shaped section having a U-shaped cross section. It is provided at both ends of the groove 10. However, it is not limited to the U-shaped groove, but is also shown in FIG.
As shown in FIG. 5, it may be constituted by a pair of arcuate grooves 10a.

Further, as shown in FIG. 2A, a second U-shaped groove 11 in which the unloaded ball passage 4 is formed is provided between the first U-shaped grooves 10 on the inner circumference of the outer cylinder 3. Has been. A first resin portion 12 extending over the entire length of the outer cylinder 3 in the longitudinal direction is integrally fitted in the second U-shaped groove 11. The first resin portion 12 has a thick-walled, substantially arcuate cross-section, and approximately half the outer diameter end portion of the first resin portion 12 is integrally fitted in the second U-shaped groove 11 in the thickness direction, and the inner diameter end portion of the outer cylinder 3 is formed. It projects inward from the inner circumference.

An unloaded ball passage 4 is formed in the first resin portion 12. This unloaded ball passage 4
Is constituted by a circular through hole having a diameter slightly larger than that of the ball 9, and is constituted so that its center position substantially coincides with the inner diameter of the outer cylinder 3.

Further, the circumferential side edge 6a of the inner diameter end of the first resin portion 12 projects toward the adjacent first U-shaped groove 10 side.

On the outer periphery of the outer cylinder 3, at its central portion,
A lubricant guide groove 13 for flowing a lubricant extending over the entire circumference is provided, and the lubricant guide groove 13 and the second U-shaped groove 11 on the inner peripheral side communicate with each other through a first communication hole 14. And further, the first communication hole 14 is provided in the first resin portion 12.
And the second communication hole 15 that communicates between the unloaded ball passages 4
Is provided. A key groove 3a extending in the axial direction is formed on the outer circumference of the outer cylinder 3.

The first U-shaped groove 10 is provided with a second resin portion 16 for holding the ball 9. The circumferential side edge 6b of the second resin portion 16 and the circumferential side edge 6a of the first resin portion 12 face each other with a distance smaller than the diameter of the ball 9, and It constitutes a ball holding portion that prevents the ball from falling off.

As shown in FIGS. 2 (b) and 3, the first resin portion 12 and the second resin portion 17 are integrated in an annular third resin portion 18 joined to both end surfaces of the outer cylinder 3. It is connected to the.

On the end face of the third resin portion 18, the end portion of the loaded ball rolling groove 2 extending linearly and the unloaded ball passage 4 are provided.
Is open, and an arcuate direction change path inner peripheral portion 19a is provided between the loaded ball rolling groove 2 and the unloaded ball passage 4.

On the other hand, as shown in FIG. 5, the side cover 5 attached to the end face of the outer cylinder 3 is an annular member, and the third resin portion 1 is formed.
8 has an annular end face that is abutted against the annular end face of 8, and the circular arc groove that constitutes the direction change path outer peripheral portion 19b is formed on the end face.
The third resin portion 18 is provided with recesses corresponding to the six inner circumferential portions 19a of the direction changing passage formed on the end surface of the third resin portion 18.

An annular wall 22 fitted to the outer peripheral surface of the third resin portion 18 on the outer cylinder 3 side is attached to the outer diameter end of the side cover 5.
Is provided, and the third resin portion 18 is provided on the inner periphery of the annular wall 22.
A locking projection 23 that locks in a locking groove 21 provided on the outer periphery is provided. The end surface of the annular wall 22 contacts the end surface of the outer cylinder 3.

The first of the above-mentioned unloaded ball passages
The resin portion 12 and the first resin portion 12 constituting the ball holding portion 6.
The second resin portion 17, and the third resin portion 18 that constitutes the rolling element direction change path inner peripheral portion 19a are all integrally formed with the outer cylinder 3 by insert molding in which the outer cylinder 3 is arranged in the mold. ing.

FIG. 6 shows a fitted state of the outer cylinder 3 and the mold during insert molding.

The insert molding of the outer cylinder 3 is performed by disposing the outer cylinder 3 between a first mold 40 and a second mold 41 which are concentrically arranged with respect to the load ball rolling groove 2. A cavity 12a for forming the first resin portion 12 forming the unloaded ball passage 4, a cavity 16a for forming the second resin portion 16 forming a ball holding portion, and a ball direction changing passage inner peripheral portion 19a.
A cavity 19c for molding and a cavity 18a for forming the third resin portion 18 are formed, and each cavity 12a,
A resin material is injection-filled into 16a, 18a, and 19c to mold the first resin portion 12, the second resin portion 16, the third resin portion 18, and the inner peripheral portion 19a of the direction change path.

As described above, since the outer cylinder 3 is positioned in the first and second molds 40 and 41 with reference to the load ball rolling groove 2, the load ball rolling groove 2 and the first mold 40 are positioned. It is possible to prevent the occurrence of burrs between and. Particularly, in the present embodiment, the ball rolling groove set 2A is basically at three places, and the outer cylinder 3 is positioned by the first mold 40 at three points. Moreover, because of the angular contact structure, positioning in the rotational direction is performed, and the outer cylinder 3 is accurately positioned with respect to the first mold 40.

If the outer periphery of the outer cylinder 3 to be insert-molded is ground with reference to the loaded ball rolling groove 2,
The gap between the contact surface between the outer periphery of the outer cylinder 3 inserted into the mold and the second mold 41 can be set as small as possible, and the occurrence of burrs on the outer peripheral side can be prevented.

Here, in order to prevent burrs, the outer cylinder 3
The contact surface between the mold and the mold does not have to be in complete contact, and even if there is a gap, it may have a size that can prevent the infiltration of the molding material. As in the present invention, the outer circumference is ground and finished with the loaded ball rolling groove 2 as a reference, and the outer cylinder 3 is arranged in the mold with the loaded ball rolling groove 2 as a reference. The gap can be set to a small constant size that can prevent the inflow of molding material. Further, not only on the outer peripheral side of the outer cylinder 3 but also between the load ball rolling groove 2 on the inner peripheral side and the first mold 40, a small constant size is set so as to prevent the inflow of the molding material. be able to. Since the loaded ball rolling groove 2 is also ground and finished, the die and the loaded ball rolling groove 2 come into contact with each other within a certain gap.

As described above, if a small gap is provided between the first and second molds 40 and 41 and the inner and outer peripheries of the outer cylinder 3, the outer cylinder 3 can be easily mounted and burrs are prevented from occurring. be able to.

As described above, all of the unloaded ball passage 4, the ball holding portion 6 and the direction changing passage inner peripheral portion 19a are insert-molded with reference to the loaded ball rolling groove 2 provided on the inner periphery of the outer cylinder 3. Since it is integrally molded by the above, the assembly can be performed by simply assembling the side lid 5, and the assembly process can be significantly reduced.

Further, there is no step due to an assembly error in the joint between the direction changing path 19 and the loaded ball rolling groove 6 and between the direction changing path 19 and the unloaded ball path 4, so that the balls circulate smoothly. Also, the generation of noise is reduced.

In this embodiment, the unloaded ball passage 4, the ball holding portion 6 and the direction changing passage inner peripheral portion 19a are all integrally formed with the outer cylinder by insert molding, but at least one of them may be insert molded. Good.

FIG. 7 shows a second embodiment of the present invention.

The second embodiment is an example in which the unloaded ball passage is provided in the outer peripheral portion of the outer cylinder.

In this example, the unloaded ball passage 4 is the outer cylinder 3
It is different from the first embodiment in that it is provided on the outer peripheral side. That is, the second U-shaped groove 51 is provided on the outer circumference of the outer cylinder 3, and the unloaded ball passage 4 is formed in the second resin portion 51 integrally molded so as to fill the second U-shaped groove 51.

Since the other structure and operation are the same as those of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 8 shows a third embodiment of the present invention.

In the third embodiment, the entire outer cylinder 33 is molded with a resin 332 having a thin cylindrical metal core 331 embedded therein.

That is, in the first and second embodiments, the outer cylinder 3 is made of a highly rigid thick metal block body, but in the third embodiment, the outer cylinder 33 is a thin-walled cylindrical core metal. It is intended to reduce the weight as a resin molded product having 331. And, in this third embodiment also, the unloaded ball passage 3
4, the ball holding portion 36, and the inner circumferential portion 319a of the direction change path.
All of the above are integrally molded with the outer cylinder 3 by insert molding.

The core metal 331 is composed of a thin cylinder such as SUS, and the loaded ball rolling groove 32 is formed on the inner circumference of the core metal 331.
Are evenly distributed in three places. This load ball rolling groove 32
Is obtained by plastically deforming the inner circumference of the core metal 331 into a circular arc shape in section so as to be partially convex outward.
By the work hardening of the material due to this plastic deformation, the hardness of the loaded ball rolling groove 32 is increased so as to withstand the load. An unloaded ball passage 34 is provided on the inner circumference of the core metal 331 at a position adjacent to the loaded ball rolling groove 32.

The loaded ball rolling groove 32 is formed in the exposed inner peripheral portion of the exposed core metal 331 by partially exposing the inner peripheral surface of the core metal 331 covered with the resin 332.

On the other hand, the unloaded ball passage 34 is constituted by a through hole having a circular cross section formed through the resin 332 of the outer cylinder 33. The unloaded ball passage 34 is located inside the resin 332 and is exposed on the inner peripheral side. I haven't. However, the unloaded ball passage 34 may also be exposed on the inner peripheral side so that the balls do not fall off. Further, an unloaded ball rolling groove 34a formed on the inner circumference of the core metal 331 is exposed at the inner circumference of the unloaded ball passage 34 to form an inner peripheral surface of the unloaded ball passage 34.

Further, the ball 39 is loaded into the loaded ball rolling groove 32.
The direction changing path 319 for changing the direction from the end portion of the to the unloaded ball path 34 is constituted by the side lid 35 as in the first embodiment. The inner peripheral portion 319a of the direction changing path is the outer cylinder 33.
Since it is integrally formed with the side cover 35, the side cover 35 constitutes the outer peripheral portion 319b of the direction change path.

On the other hand, in this embodiment, the spline shaft 38 also has a thin pipe structure, and the load ball rolling groove 37 having an arcuate cross section is formed on the outer peripheral surface thereof. The loaded ball rolling groove 37 is also formed by plastically deforming a cylindrical pipe, and the loaded ball rolling groove 37 is hardened so as to withstand the load by work hardening due to plastic deformation. The terminal opening of the spline shaft 38 is sealed with a plug 38a, and the plug 38a is fixed with a knock pin or the like.

[0066]

As described above, according to the present invention,
Since at least one of the outer cylinder, the unloaded rolling element passage, the rolling element holding portion, and the inner peripheral portion of the rolling element direction changing path is integrally formed by insert molding, the number of assembling steps can be reduced.

Further, by integrally molding, a step is not generated due to an assembly error at the joint between the rolling element direction change path and the loaded rolling element rolling groove, and between the direction change path and the unloaded rolling element rolling groove. Circulation of rolling elements becomes smooth and noise is reduced.

Furthermore, since the outer cylinder is positioned in the mold with reference to the load rolling element rolling groove, burrs between the load rolling element rolling groove and the die can be prevented. Therefore, there is no risk of problems such as poor feed accuracy due to poor circulation of rolling elements or stoppage of the feeding device due to clogging of rolling elements, and smooth smooth circulation of rolling elements is always guaranteed, ensuring precise feeding accuracy. can do.

If the outer periphery of the outer cylinder to be insert-molded is ground with reference to the rolling groove of the load rolling element, a gap between the outer periphery of the outer cylinder inserted into the mold and the contact surface of the mold can be formed. It can be set as small as possible, and the occurrence of burrs on the outer peripheral side can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a spline unit according to a first embodiment of the present invention.

2 (a) is a vertical sectional view of the spline unit of FIG. 1, and FIG. 2 (b) is a sectional view of the ball circulation path of FIG. 2 (a).

3 is a view showing an end face of the outer cylinder of the spline unit shown in FIG. 1, and FIG. 3 (a) is a view showing a state in which balls are filled;
FIG. 3B is a diagram showing a state where the ball is removed.

4 (a) is a semi-longitudinal sectional view of the outer cylinder, FIG. 4 (b) is a plan view of a key groove, FIG. 4 (c) is a central longitudinal sectional view of FIG. 4 (a), and FIG. FIG. 7D is a partial cross-sectional view of the ball rolling groove portion in the case of an arc groove.

5A is a vertical cross-sectional view of the side lid, FIG. 5B is a rear view of the side lid with a ball attached, and FIG. 5C is a back surface of the side lid with the ball removed. The figures, (d) and (e) are views showing the engagement state of the outer cylinder and the side lid.

FIG. 6 is a diagram showing a schematic process of an outer cylinder forming method of the present invention.

FIG. 7 is a vertical sectional view of a spline unit according to a second embodiment of the present invention.

8 (a) is a sectional view of a spline unit of a third embodiment of the present invention, FIG. 8 (b) is a sectional view of the outer cylinder of FIG. 8 (a),
7C is a sectional view of the spline shaft, FIG. 8D is a sectional view of the end of the spline shaft, and FIG. 8E is a partial sectional view of the ball circulation path.

FIG. 9 is a diagram showing a conventional linear motion bearing.

[Explanation of symbols]

1 spline unit 2 Load ball rolling groove (outer cylinder side) 3 outer cylinder 4 no-load ball passage 5 side lid 6a Edge of first resin portion (ball holding portion) 6b Edge of second resin portion (ball holding portion) 7 Ball rolling groove (Spline shaft side) 8 spline shaft 8a corner 9 balls (rolling elements) 10 First U-shaped groove 11 Second U-shaped groove 12 Second resin part 18 3rd resin part 19a Directional change road inner circumference 19b Peripheral part of turning path

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-53-56449 (JP, A) JP-A-2-228013 (JP, A) JP-A 63-73541 (JP, A) JP-A 59- 155617 (JP, A) JP-A-6-58331 (JP, A) JP-A-7-4433 (JP, A) JP-A-2-142918 (JP, A) Actual development Sho-61-179414 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16C 29/06 F16C 31/06

Claims (6)

(57) [Claims] 1. A cylindrical outer cylinder having a plurality of load rolling element rolling grooves formed on an inner circumference thereof, and a plurality of unloaded rolling elements corresponding to the load rolling element rolling grooves provided in the outer cylinder. A passage, a side lid provided at both ends of the outer cylinder, the side lid having a direction change path connecting the load rolling element rolling groove and the unloaded rolling element passage, and a load provided along the load rolling element rolling groove. A rolling element holding portion that prevents the rolling element from falling out of the rolling element rolling groove, and a load rolling element rolling groove that is inserted into the outer cylinder and that corresponds to the load rolling element rolling groove provided on the outer cylinder on the outer periphery. A spline shaft provided with a moving groove, and a large number of rolling elements which are interposed between the load rolling element rolling grooves of the outer cylinder and the spline shaft and endlessly circulate through the direction change path and the unloaded rolling element path. In the spline unit including, the outer circumference of the outer cylinder is ground with reference to the load rolling element rolling groove.
After the lifting is performed, the outer cylinder is connected to the load rolling element rolling groove.
By insert molding that is placed in the mold with reference to
At least one of the unloaded rolling element passage, the rolling element holding portion, and the inner peripheral portion of the rolling element direction changing path is integrally formed with the outer cylinder. . 2. A cylindrical outer cylinder provided with a plurality of sets of load rolling element grooves in the circumferential direction on the inner circumference, with a pair of rolling element rolling grooves adjacent to each other as one set, and an outer cylinder. A plurality of unloaded rolling element passages corresponding to the loaded rolling element grooves provided on the outer peripheral portion, and a direction change path provided at both ends of the outer cylinder and connecting the loaded rolling element groove and the unloaded rolling element passage. Side cover, a rolling element holding portion that is provided along the load rolling element groove to prevent the rolling element from falling out of the load rolling element groove, and is inserted into the outer cylinder, and each load rolling element rolling portion is provided on the outer periphery. It has a plurality of corners located between a pair of load rolling element rolling grooves that form a dynamic groove set, and corresponds to a pair of load rolling element rolling grooves provided on the outer cylinder on both sides of the corners. And a spline shaft provided with a pair of load rolling element rolling grooves, and is interposed between the load rolling element rolling grooves of the outer cylinder and the spline shaft. In spline unit and a plurality of rolling elements which endless circulation through the direction changing passage and the unloaded rolling member escape passage, the outer cylinder periphery, specification grinding based on the load rolling grooves
After the lifting is performed, the outer cylinder is connected to the load rolling element rolling groove.
Insert that inserts into the mold based on
By molding, the no-load rolling element passage, the rolling element holder and of the rolling element direction changing passage inner peripheral portion, the spline unit, characterized in that at least any one, formed integrally with the outer cylinder. 3. A cylindrical outer cylinder having a pair of load rolling element rolling grooves adjacent to each other on the inner circumference and provided with a plurality of sets of load rolling element grooves in the circumferential direction, and an inner circumference of the outer cylinder. And a plurality of no-load rolling element passages provided corresponding to the respective load rolling element grooves between the plurality of load rolling element groove sets, and the load rolling element grooves provided at both ends of the outer cylinder. And a side cover provided with a direction change path connecting the unloaded rolling element passages, a rolling element holding portion that is provided along the load rolling element groove to prevent the rolling element from falling out of the load rolling element groove, and the outer portion. The outer cylinder has a plurality of corners that are inserted into the cylinder and that are located between a pair of load rolling element rolling grooves that make up each load rolling element rolling groove set on the outer circumference. A pair of load rolling element rolling grooves corresponding to the pair of load rolling element rolling grooves, and a spline shaft, and the outer cylinder and the spline. Is interposed between the load rolling element rolling grooves, in the direction changing passage and the unloaded rolling element relief spline unit having a plurality of rolling elements infinitely circulating through the passage, and the outer cylinder periphery, said Grinding based on the rolling groove of the load rolling element
After the lifting is performed, the outer cylinder is connected to the load rolling element rolling groove.
Inserts performing molding by in the reference placed in a mold
By molding, the no-load rolling element passage, the rolling element holder and of the rolling element direction changing passage inner peripheral portion, the spline unit, characterized in that at least any one, formed integrally with the outer cylinder. 4. The outer cylinder is formed of a resin having a thin-walled cylindrical cored bar embedded therein, and the inner peripheral surface of the cored bar covered with the resin is partially exposed. The spline unit according to claim 1, wherein a load rolling element rolling groove is formed in the exposed portion. 5. The outer circumference of the outer cylinder is based on the rolling groove of the load rolling element.
Perform finish grinding Te, then the outer tube, the load rolling grooves in the reference and placed in a mold and no-load rolling element passage, the rolling element retaining portion and the rolling element direction changing passage inner periphery portion Of
A method for forming an outer cylinder of a spline unit in which at least one of them is integrally formed by insert molding. 6. The contact state between the load rolling element rolling groove and the die is
The outer cylinder molding method for a spline unit according to claim 5, wherein the outer cylinder molding method is set by allowing a gap to the extent that the molding material can be prevented from entering.