JP2001099256A - Method for assembling ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for assembling a ball screw device to facilitate insertion of a ball to a ball circulation route, prevent dislocation of the ball to the outside of the circulation route, and visually inspect the insertion state of the ball and a holder. SOLUTION: This method is one for assembling in a way to insert a ball in a ball circulation route 8 consisting of a helical passage consisting of the screw groove 1a of a ball screw shaft 1 and the screw groove 2a of a ball nut 2 positioned facing the screw groove 1a and a ball circulation route 4A to guide and circulate a number of balls B rolling in the helical passage. An opening part 9 for inserting a ball is formed in the ball circulation route 4A and previously incorporated in the ball circulation passage 8. After the ball B is then inserted in the opening part 9 to fill the ball circulation passage 8, the opening part 9 is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for assembling a ball screw device, and more particularly to an improvement in a method for inserting a ball into a ball circulation path.

[0002]

2. Description of the Related Art As a type of circulating balls in a ball screw, as shown in FIG. 4, a U-shaped ball tube 4A as a ball circulating member having a ball circulating path is used to move a ball B to the outside of a ball nut 2. An external circulation type such as a tube type that guides and circulates, or an end cap type that circulates through a ball circulation path 24 provided in an end cap 22 as a ball circulation member attached to both ends of the nut 2 as shown in FIG. It is well known that there is an internal circulation type (not shown) in which a ball is circulated along the outer surface of a screw shaft by a circulation piece as a ball circulation member provided on a ball nut.

The ball tube 4A is fixedly attached to a nut body by a tube holding plate and a screw (not shown), and the end cap 22 is fixed to a nut body by a screw. On the other hand, in the case of a circulating piece, an adhesive such as a metal bond is used. Fixedly mounted. When assembling the ball screw device, these ball circulation members are first removed from the ball nut. Then, with the screw shaft inserted into the ball nut, the ball is filled into the screw groove between the screw shaft and the nut. Also, the ball is separately filled in the ball circulation path of the ball circulation member. Thereafter, the ball circulation member, which is also filled with the ball, is assembled and fixed to the ball nut, and the assembly is completed.

For example, in the case of a tube type,
With the ball tube 4A removed as shown in FIG. 6, the ball B is filled into the thread groove between the screw shaft and the nut from the tube insertion hole 7 on the nut surface. On the other hand, the ball tube 4A in the detached state is separately filled with a predetermined number of balls B in advance. The ball in the tube 4A is held down by grease or the like so as not to fall, and the legs of the ball tube 4A are inserted into the pair of tube insertion holes 7, 7 on the nut surface and attached, and fixed by a tube pressing member (not shown).

[0005]

However, in the conventional method of assembling the ball screw device, since the ball circulation path is not yet closed when the ball is filled, the end of the ball tube 4A is closed as shown in FIG. May enter the circuit outside portion Sg on the back side of the tube tongue T. Therefore, it is necessary for the operator to work carefully so that the ball does not come out of the portion Sg outside the circuit, which causes a long time for assembly. In addition, since the state of the inserted ball cannot be visually observed, the inspection is very difficult especially when the retainer H is inserted between the balls B.

Various proposals have been made to solve such problems. For example, Japanese Patent Application Laid-Open No. 5-138460 discloses
One using a ball insertion member 100 as shown in FIG. 8 has been proposed. The ball insertion member 100 has a ball entrance hole 101 in the upper part and a ball exit hole 102 in the middle part.
The two holes 101 and 102 are connected by a vertical ball supply path 103. The insertion member 100 is inserted into the ball nut 2 so that the ball outlet hole 102 faces the highest position of the ball circulation groove 2 a on the inner peripheral surface of the ball nut 2, and the ball B is supplied from the ball inlet hole 101. The ball is inserted smoothly. After the ball insertion is completed, the screw shaft 1 is screwed and assembled at the same time while the ball insertion member 100 is removed.

However, in this case, the ball insertion member 100 must be prepared as a temporary shaft for each nut, and the apparatus becomes complicated. Moreover, since the assembled state of the circulating parts such as the ball and the retainer cannot be visually observed, the problem that the ball is detached from the circuit outside portion is still unresolved, and it is difficult to automate the assembling work of the ball screw device. is there. In particular, when the cage is filled together with not only the balls, it is necessary to check the filling ratio with respect to the entire circuit length of the cage, the state of the holder falling down, and the like.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and it is easy to insert a ball into a ball circulation path, and the ball is detached out of the circulation path. It is an object of the present invention to provide a method of assembling a ball screw device capable of visually inspecting the inserted state of a ball and a retainer without any trouble.

[0009]

In order to achieve the above object, according to the present invention, there is provided a helical passage formed by a thread groove of a ball screw shaft and a thread groove of a ball nut opposed thereto. And a ball circulation path for guiding and circulating a number of balls rolling in the spiral path. A method of assembling by inserting a ball into a ball circulation path, wherein an opening for inserting a ball is provided in the ball circulation path, the ball is inserted into the ball circulation path in advance, and then the ball is inserted through the opening. After filling the circulation path, the opening is closed.

Here, the ball is a generic term for a ball, a spacer ball, a retainer, and the like. According to the present invention, before inserting the ball, since the ball circulation member having the ball circulation path is assembled to the ball nut and the ball circulation path is already closed, when the ball is inserted from the opening of the ball circulation path, The ball does not come out of the ball circulation path. Further, since the ball can be smoothly filled in the closed ball circulation path in the closed state, the assembly of the ball screw device can be automated in combination with the automatic ball feeder.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, as a first embodiment,
The case where the present invention is applied to an external circulation type tube ball screw will be described. FIG. 1 is a partially cutaway perspective view. The screw shaft 1 has a ball screw groove 1a having an arc-shaped cross section on its outer surface. The ball nut 2 is a substantially cylindrical member and has on its inner surface a ball screw groove 2a corresponding to the ball screw groove 1a of the screw shaft on its inner surface. Thus, a spiral path in which the ball B rolls is formed.

A part of the outer peripheral surface of the ball nut 2 is cut into a flat surface 4, and a mounting flange 5 is formed on the outer periphery at one end. The flat surface 4 of the ball nut 2 is provided with two pairs of two tube mounting holes 7 into which both ends of a U-shaped ball tube 4A are inserted, and each hole 7 penetrates through the thickness of the ball nut 2. And communicate with the ball screw groove 2a on the inner surface of the nut.

A ball tube 4A, which is a ball circulating member, is mounted so as to be inclined with respect to the axial direction of the nut in such a manner that the pair of tube mounting holes 7, 7 are connected to each other. Ball circulation paths 8 (two sets in the case of the figure) are formed. A large number of balls B filled in the ball circulation path 8 circulate while rolling in the path along with the rotation of the screw shaft 1, so that the ball nut 2 moves relatively along the screw shaft 1. It is supposed to.

In the present invention, the ball B
Before inserting and filling the ball, the ball circulation path 8 is assembled.
That is, in the ball tube 4A of the present invention, an opening (ball insertion hole) 9 for inserting a ball is provided on the outer surface at an intermediate position of the tube as shown in the figure. Both ends of the ball tube 4A are inserted into the tube mounting hole 7 while being empty, and attached to the ball circulation path 8. Next, the ball B (alternately with the cage H when the cage H is used) is inserted from the ball insertion hole 9.

In a state in which a predetermined number of balls B (and retainers H) are filled in a ball circulation path 8 composed of a spiral passage and a ball tube 4A, the number of balls B (and retainers H) and the inserted state are inspected. I do. When it is confirmed that the retainer H has a predetermined filling rate, that the retainer H has not fallen, and that both are inserted at a predetermined ratio, etc., the ball is inserted with the ball insertion hole lid 10 as shown in FIG. Close the opening of the hole 9,
Further, it is held down by the tube holder 11 and fixed by the screw 12.
However, the ball insertion hole lid 10 may be integrated with the tube holder 11.

According to the first embodiment, since the ball insertion hole 9 can be formed at the same time when the ball tube 4A is press-formed, the cost is not increased, and the ball insertion hole cover 10 is also formed of a ball screw. This is advantageous in terms of cost because it is sufficient to prepare for each tube diameter regardless of the shaft diameter and the lead. Next, a second embodiment applied to a tube type ball screw will be described.

This embodiment differs from the first embodiment in that the tube retainer is formed of a block material so that the lid of the ball insertion hole 9 of the ball tube 4A and the tube are also used. . That is, as shown in FIG.
A semicircular groove 15 having the same inner diameter as the ball tube 4A is formed in the pressing surface 14 of the block-shaped tube holder 13. The ball insertion hole is formed only by screwing the tube holder 13 to the ball nut 2 after filling the ball. 9 can be closed and the ball tube 4A can be fixed. Other functions and effects are the same as those of the first embodiment.

Next, a description will be given of a third embodiment in which the present invention is applied to an external circulation type end cap type ball screw. FIG. 3 is an axial sectional view of the ball screw device. The ball nut 2 is an end cap 22 which is a disc-shaped ball circulating component detachably joined to a nut body 21 and both end surfaces in the axial direction. And two members. A ball return passage 23 formed of an axial through hole is provided in a thick portion of the nut body, while a ball screw groove of the screw shaft 1 is provided on an end surface of the end cap 22 on the joining side with the nut body 21. A curved path 24 is provided for communicating the helical path formed by the ball screw groove 2a on the inner peripheral surface of the ball nut 1a and the ball return path 23 with the ball return path 23.

The spiral passage, the ball return passage 23 and the curved passage 24 form a ball circulation passage 26. In the case of the present embodiment, an opening (ball insertion hole) 29 for inserting a ball communicating with the outside is provided in the curved path 24 of at least one end cap 22.
Both end caps 22, 22 are attached to both ends of the ball nut 2 with the inside of the ball circulation path 26 being empty. Thereafter, a predetermined number of balls B (and a retainer, etc.) are filled into the ball circulation path 26 from the ball insertion hole 29, and an inspection is performed. Close with agents.

In the case of the end cap type ball screw device targeted in this embodiment, there is basically no room for the generation of balls outside the circulation accounting path, but other operational effects are as described in the first embodiment. This is the same as the embodiment.

[0021]

As described above, according to the first aspect of the present invention, an opening for inserting a ball is provided in a ball circulation path composed of a ball tube or the like, and the opening is provided on a ball nut to attach the ball. After assembling the circuit,
Since the filling material such as a ball is inserted and filled through the opening, it is easy to insert the ball and the retainer into the ball circulation path, and the ball does not come out of the circulation path, and the ball is visually inserted. This has the effect that the state can be inspected.

[Brief description of the drawings]

FIG. 1 shows a first method of assembling a ball screw device according to the present invention.
It is a perspective view explaining Embodiment of this invention.

FIG. 2 is a diagram for explaining a second embodiment of the present invention;
(A) is a sectional view of a ball tube holder, and (b) is a partially cutaway perspective view of a ball screw device.

FIG. 3 is an axial sectional view of a ball screw device for explaining a third embodiment of the present invention.

FIG. 4 is an assembled sectional view of a main part of a conventional ball screw device.

FIG. 5 is an assembled sectional view of a main part of another conventional ball screw device.

FIG. 6 is a partially cutaway perspective view for explaining a method of assembling a conventional ball screw device.

FIG. 7 is a view for explaining a defect of a conventional ball screw device assembling method.

FIG. 8 is a sectional view for explaining a method of assembling a conventional ball screw device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw shaft 1a Screw groove (of ball screw shaft) 2 Ball nut 2a Screw groove (of ball nut) 4A Ball circulation path (ball tube) 8 Ball circulation path

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Takeshi Nakazawa 78 Tobacho, Maebashi-shi, Gunma Nippon Seiko Co., Ltd. (72) Inventor Kazuo Miyaguchi 78 Tobacho, Maebashi-shi, Gunma Nippon Seiko Co., Ltd. (72) Inventor Hitoshi Sannomiya 78 Toba-cho, Maebashi-shi, Gunma Nippon Seiko Co., Ltd. (72) Inventor Akio Sakai 78, Toba-cho, Maebashi-shi, Gunma Pref.

Claims (1)

[Claims] 1. A helical passage formed by a thread groove of a ball screw shaft and a thread groove of a ball nut opposed thereto, and a ball circulation for guiding and circulating a number of balls rolling in the helical passage. In the ball circulation path consisting of the road,
A method of inserting and assembling a ball, wherein an opening for inserting a ball is provided in the ball circulation path, the ball is inserted into a ball circulation path in advance, and then the ball is inserted from the opening to fill the ball circulation path. And then closing the opening of the ball screw device.