JP2003343683A - Linear motion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibration and noise of a device and to improve accuracy and service life of the device. <P>SOLUTION: A ball screw device comprises: a screw shaft 3 having a screw groove 2 extending axially and extending axially; a nut 6 having a screw groove 4 facing to the screw groove 2 and being supported by the screw shaft 3 relatively movable in the axial direction via rolling of many balls 5 inserted between both screw grooves 2 and 4; and a circulation tube 20 mounted to the nut 6 and for infinitely circulating the balls 5 rolling between both screw grooves 2 and 4. The circulation tube 20 radially joins a pair of half members 20a and 20b for the tube to each other. A projecting part 21 and a recessed part 22 engaged with respective joint surfaces of the pair of members 20a and 20b are formed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion device such as a ball screw device used in a feed mechanism of various equipment.

[0002]

2. Description of the Related Art As a conventional ball screw device of this type, for example, one shown in FIG. 15 is known. This ball screw device 1 has a screw shaft (guide shaft) 3 that has a spiral screw groove (rolling element rolling groove) 2 on its outer peripheral surface and extends in the axial direction.
A nut (movable body) 6 having a spiral thread groove (rolling element rolling groove) 4 corresponding to the thread groove 2 is loosely fitted on the inner peripheral surface. The screw groove 4 of the nut 6 and the screw groove 2 of the screw shaft 3 face each other to form a spiral load path between the screw grooves 2 and 4, and the load path includes a large number of rolling elements as rolling elements. A ball 5 is rotatably loaded. And the screw shaft 3
The rotation of (or the nut 6) causes the nut 6 (or the screw shaft 3) to move in the axial direction through the rolling of the ball 5.

When the nut 6 (or the screw shaft 3) moves in the axial direction, the ball 5 moves while rolling on the load path formed between the screw grooves 2 and 4, but the nut 6 In order to continuously move (or the screw shaft 3), the ball 5 needs to be infinitely circulated. Therefore, for example, a part of the outer peripheral surface of the nut 6 is made a flat surface, and a pair of holes 7 communicating with the load path is formed on the flat surface so as to straddle the screw shaft 3. By fitting both ends of a U-shaped ball circulation tube 8 as a ball circulation member into 7 and pressing the ball circulation tube 8 against the nut 6 with a tube retainer (not shown) or the like, both screw grooves 2,
The balls 5 revolving along the load path between the four are picked up from the middle of the load path by the ball circulation tube 8 and returned to the original load path, whereby the balls 5 are infinitely circulated.

The ball circulation tube 8 is usually divided into two along the axial direction, and a pair of divided half tube members 8a and 8b (see FIGS. 16 and 17) are provided. After being joined in the radial direction to form a U-shaped tube shape, in this state, it is fitted into the hole 7 of the nut 6 and then fixed to the nut 6 by the above-mentioned tube retainer or the like. This is a ball circulation tube 8
Is a pair of half-divided tube members 8a, 8
This is because b can be formed by forging, so that the processing time and cost can be significantly reduced as compared with the case of bending a pipe material to form a U-shaped tube shape.

[0005]

In the above-mentioned conventional ball screw device, the diameter of the hole 7 of the nut 6 into which both ends of the ball circulation tube 8 are fitted is sufficiently larger than the outer diameter of the ball circulation tube 8 so that the clearance fits. Since,
The ball circulation tube 8 is substantially fixed to the nut 6 only by the tube retainer.

However, when the ball circulation tube 8 is fixed to the nut 6 only by holding the tube in this manner, the joining surfaces of the pair of tube members 8a and 8b are flat surfaces which are slippery, so that the tube tongue portion is formed. When a ball hits or an impact load is applied to the device from the outside, as shown in FIGS. 16 and 17, there are vertical and horizontal deviations between the joint surfaces of the pair of tube members 8a and 8b. It is easy to occur. This deviation not only adversely affects the behavior of the ball 5 in the ball circulation tube 8, but also in the ball scooping portion of the ball circulation tube 8 into which the ball 5 enters from within the load path that greatly affects the device performance. This may have an adverse effect, cause vibration and noise of the device, and may cause deterioration of accuracy and device life.

The present invention has been made in order to eliminate such inconvenience, and it is possible to reduce the vibration and noise of the device and to improve the accuracy and the life of the device. The purpose is to provide.

[0008]

In order to achieve the above object, the invention according to claim 1 has a guide shaft extending in the axial direction having a rolling element rolling groove extending in the axial direction, and the guide shaft. It has a rolling element rolling groove that opposes the rolling element rolling groove of the shaft, and relatively moves along the axial direction through the rolling of a large number of rolling elements inserted between these rolling element rolling grooves. A movable body supported by the guide shaft is provided, and a circulation tube attached to the movable body for infinitely circulating the rolling body rolling between the rolling element rolling grooves is provided. In a linear motion device constituted by joining half-divided tube members to each other in a radial direction, a deviation preventing means for preventing deviation of the joining surfaces is provided between respective joining surfaces of the pair of tube members. It is characterized by

According to a second aspect of the present invention, in the first aspect, the deviation preventing means is an uneven portion formed on each joint surface of the pair of tube members and fitted to each other. . According to a third aspect of the present invention, in the first aspect, the displacement prevention means is provided with a spacer interposed between the joint surfaces of the pair of tube members, and the spacer is provided integrally with the spacer. A deviation preventing member including a flange portion having a shape corresponding to the outer peripheral surface of the tube.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a holding piece is interposed between the rolling elements of the plurality of rolling elements.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that, in each of the embodiments, only the configuration of the ball circulation tube is different from that of the conventional ball screw device described in FIG. 15, so only the ball circulation tube will be described. 1A and 1B are views for explaining a ball circulation tube of a ball screw device according to a first embodiment of the present invention, in which FIG. 1B is a front view and FIG.
1 is a left side view, FIG. 2 (c) is a right side view of FIG.
FIGS. 3 to 14 are plan views seen from above in (b), and FIGS. 3 to 14 are views for explaining a ball circulation tube of a ball screw device according to another embodiment of the present invention.

First, the ball circulation tube of the ball screw device according to the first embodiment of the present invention will be described. The ball circulation tube 20 is formed along the axial direction as shown in FIGS. 1 and 2. The tube member 20 is divided into two and is divided into a pair of half-divided tube members 20 as in the conventional case.
A and 20b are joined to each other in the radial direction to form a U-shaped tube shape, which is fitted into the hole 7 of the nut 6 in this state and then fixed to the nut 6 by a tube retainer or the like.

Here, in this embodiment, the joint surface on the lower end side of the upper surface and the right side surface of the one tube member 20a becomes gradually narrower toward the joint surface on the other tube member 20b side. A trapezoidal convex portion (displacement preventing means) 21 is extended, and a concave portion (displacement preventing means) 2 into which the convex portion 21 is fitted on the joint surface on the other tube member 20b side.
Two are provided.

Further, a trapezoidal convex portion 21 gradually narrowed toward the joint surface on the side of the one tube member 20a is formed on the joint surface on the lower end side of the upper surface and the left side surface of the other tube member 20b. A concave portion 22 into which the convex portion 21 is fitted is provided on the joint surface of the tube member 20a which is extended. Convex portion 2 on one tube member 20a side
1 and the concave portion 22 and the convex portion 21 and the concave portion 22 of the other tube member 20b are arranged point-symmetrically with respect to the point O which is the center of the ball circulation tube 20.

By fitting the convex portion 21 and the concave portion 22 of the one tube member 20a into the concave portion 22 and the convex portion 21 of the other tube member 20b, respectively, the two tube members 20a and 20b are joined together. The ball circulation tube 20 is configured. As a result, when the ball 5 collides with the tube tongue portion or an impact load is applied to the device from the outside, the pair of tube members 20a, 2
It is possible to satisfactorily prevent vertical and horizontal deviations from occurring on the joint surfaces of 0b, and as a result, it is possible to reduce vibration and noise of the device and to improve accuracy and life of the device. be able to.

Further, the convex portion 21 and the concave portion 22 of the one tube member 20a are respectively replaced by the other tube member 2a.
Since the two are positioned by fitting into the concave portion 22 and the convex portion 21 of 0b, such positioning can be performed easily and reliably. Further, the tube member 20a
Since the convex portion 21 and the concave portion 22 on the side and the convex portion 21 and the concave portion 22 on the side of the tube member 20b are arranged point-symmetrically with respect to the point O which is the center of the ball circulation tube 20, a pair of the member 20a for the tube is provided. , 20b have the same shape, so that the molds for molding the pair of tube members 20a, 20b can be unified into one mold, and the molds have a convex portion 21 and a concave portion as compared with the conventional mold. Since it is only necessary to change a part corresponding to No. 22, it is possible to manufacture at the same cost as the conventional one.

The present invention is not limited to the above-mentioned embodiments, but can be modified as appropriate without departing from the gist of the present invention. For example, in the first embodiment, the convex portion 21 and the concave portion 22 are provided on the outer surface side of the ball circulation tube, but the convex portion 21 and the concave portion 22 may be provided on the inner surface side of the ball circulation tube. .

In the first embodiment, the convex portion 2
1 and the concave portion 22 have a trapezoidal shape,
Without being limited to this, like the ball circulation tube 30 of the ball screw device of the second embodiment shown in FIGS. 3 and 4, the pair of tube members 30a and 30b have semicircular convex portions 21 and You may make it provide the recessed part 22 and improve the displacement prevention effect.

Further, in the first embodiment, the convex portion 21 and the concave portion 22 are arranged on the linear portion of the ball circulation tube 20, but instead of this, the third portion shown in FIGS. 5 and 6 is used. Like the ball circulation tube 40 of the ball screw device of the embodiment, the same convex portion 2 is formed on the pair of tube members 40a and 40b located on the curved portions on the left and right sides.
It is also possible to provide one recess 1 and one recess 22 to prevent vertical and horizontal misalignment. By doing so, the number of convex portions 21 and concave portions 22 can be reduced. In this case as well, the protrusions 21 and the recesses 22 may of course be semicircular.

Further, in the first embodiment, as the deviation preventing means, the convex portion 21 and the concave portion 22 formed on the respective joint surfaces of the pair of tube members 20a and 20b and fitted to each other are taken as an example. However, the invention is not limited to this, and as a deviation preventing means, for example, as in the fourth embodiment shown in FIGS. 7 and 8, it is interposed between the pair of tube members 50a and 50b of the ball circulation tube 50. The upper deviation prevention member 60 and / or the lower deviation prevention member 70 may be employed.

The upper deviation preventing member 60 is a spacer 61 interposed between the upper joint surfaces of the pair of tube members 50a and 50b having an arcuate cross section, and a pair of spacers integrally provided with the spacer 61. And a flange portion 62 having a shape corresponding to the outer peripheral surface on the upper side of the tube members 50a and 50b. On the other hand, similarly, the lower shift preventing means 70 is also provided integrally with the spacer 71 interposed between the lower joint surfaces of the pair of tube members 50a and 50b having an arcuate cross section, and the spacer 71. And a flange portion 72 having a shape corresponding to the lower outer peripheral surface of the pair of tube members 50a and 50b.

The spacer 61 of the upper shift preventing member 60 is provided.
Is interposed between the upper joint surfaces of the pair of tube members 50a, 50b to apply the flange portion 62 to the upper outer peripheral surfaces of the pair of tube members 50a, 50b, and between the lower shift prevention means 70. The seat 71 to the pair of tube members 5
0a, 50b is interposed between the respective lower joint surfaces, and the flange portion 72 is applied to the lower outer peripheral surfaces of the pair of tube members 50a, 50b.
It is possible to favorably prevent the vertical and horizontal deviations from occurring on the joint surfaces of a and 50b, and at the same time, to position the pair of tube members 50a and 50b.

In this case, the upper shift prevention member 60 and the lower shift prevention member 70 are made of a polymer material such as rubber or plastic and are sandwiched by tube pressers or the like, so that the spacers 61 and 71 are a pair of tube members. 50a, 5
0b can be slightly crushed between the joint surfaces to further enhance the displacement prevention effect, and the use of a polymer material can further reduce the noise generated by rolling of the ball 5 in the ball circulation tube 50. Can be increased.

The pair of tube members 50a, 50
If the spacers 61, 71 crushed between the joint surfaces of b project from the inner diameter surface of the ball circulation tube 50, it is highly possible that the rolling elements rolling in the tube 50 are prevented from passing through.
It is desirable that the dimensions of the spacers 61 and 71 be slightly smaller than the thickness of the tube 50. Further, in the upper side deviation prevention member 60 and the lower side deviation prevention member 70 shown in FIGS. 7 and 8, the flange portions 62 and 72 cover a part of the outer peripheral surface of the ball circulation tube 50. hand,
As in the fifth embodiment shown in FIG. 9, it is also possible to use the upper side deviation preventing member 64 and the lower side deviation preventing member 74 having the flange portions 63 and 73 covering the entire surface of the ball circulation tube 50.

In this way, the ball circulation tube 5
Since the outer peripheral surface of No. 0 is entirely covered, the effect of preventing the deviation can be further enhanced, and the upper side deviation preventing member 64 and the lower side deviation preventing member 74 are made of a polymer material such as rubber or plastic. In this case, the effect of reducing the noise generated in the ball circulation tube 50 is obtained, and the effect is higher than that of the fourth embodiment.

Further, the pair of tube members 5 shown in FIG.
Nos. 0a and 50b are spacers 61 and 71 interposed between the joint surfaces to form the ball circulation tube 50 having a substantially circular cross section, but instead of this, the sixth embodiment shown in FIG. Like the above-mentioned form, the pair of tube members 80a, 80
b has a semicircular cross section, and the spacers 61 and 71 are interposed between the joint surfaces to form an elliptical cross section that is long in the depth direction (see FIG. 10).
The ball circulation tube 80 (see (a)) may be used. Thereby, the friction of the ball in the ball circulation tube 80 can be reduced.

Further, as in the ball circulating tube 90 of the seventh embodiment shown in FIGS. 11 to 13, the total length in the axial direction of the joint surfaces of the pair of tube members 90a and 90b having a semicircular cross section is provided. By providing the step portion 91 and joining the step portions 91 to each other, it is possible to satisfactorily prevent the vertical and horizontal deviations from occurring in the joint surfaces of the pair of tube members 90a and 90b, and at the same time, to form the pair of tubes. The members 90a and 90b may be positioned. In the seventh embodiment, the pair of tube members 90a, 90b have the same shape, and the molds for molding the pair of tube members 90a, 90b can be unified into one mold, As for the mold, since it is sufficient to change a part corresponding to the stepped portion 91 in the conventional mold, it is possible to manufacture the mold at the same cost as the conventional mold.

Further, the ball 5 when the ball screw device is driven
In order to eliminate the collision noise between the balls and to reduce the noise, a concave surface such as an arc shape or a conical shape is formed between the balls 5 of the multiple balls 5 on both side surfaces facing the balls 5, as shown in FIG. You may interpose the holding piece 100 which has. When the holding piece 100 is used between the balls as used in the conventional ball screw device, the corners of the holding piece 100 scoop up when a deviation as shown in FIGS. 16 and 17 occurs. In this regard, since there is a possibility that it will be easily clogged here, further effects can be expected by combining it with the present invention.

[0029]

As is apparent from the above description, according to the present invention, when a rolling element collides with the tube tongue portion or an impact load is applied to the device from the outside, each of the pair of tube members is provided. Since it is possible to satisfactorily prevent the joining surface from being displaced, it is possible to reduce the vibration and noise of the device, and to improve the accuracy and the life of the device. Can be positioned easily and reliably.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a ball circulation tube of a ball screw device according to a first embodiment of the present invention, FIG.
Is a front view, (a) is a left side view of (b), (c) is (b).
FIG.

FIG. 2 is a plan view seen from above in FIG. 1 (b).

FIG. 3 is a view for explaining the ball circulation tube of the ball screw device according to the second embodiment of the present invention, FIG.
Is a front view, (a) is a left side view of (b), (c) is (b).
FIG.

FIG. 4 is a plan view seen from above in FIG.

FIG. 5 is a view for explaining the ball circulation tube of the ball screw device according to the third embodiment of the present invention, FIG.
Is a front view, (a) is a left side view of (b), (c) is (b).
FIG.

FIG. 6 is a plan view seen from above in FIG. 5 (b).

FIG. 7 is a view for explaining the ball circulation tube of the ball screw device according to the fourth embodiment of the present invention, FIG.
Is a front view in which the left side is broken, (a) is a sectional view taken along the line AA of (b), and (c) is a right side view of (b).

FIG. 8 is a plan view seen from above in FIG. 7 (b).

FIG. 9 is a view for explaining the ball circulation tube of the ball screw device according to the fifth embodiment of the present invention, FIG.
Is a front view in which the left side is broken, (a) is a sectional view taken along the line AA of (b), and (c) is a right side view of (b).

FIG. 10 is a view for explaining the ball circulation tube of the ball screw device according to the sixth embodiment of the present invention,
(B) is a front view in which the left side is broken, (a) is A- of (b)
A line sectional view, (c) is a right side view of (b).

FIG. 11 is a view for explaining the ball circulation tube of the ball screw device according to the seventh embodiment of the present invention,
(B) is a front view, (a) is a left side view of (b), (c) is a right side view of (b).

FIG. 12 is a plan view seen from above in FIG. 11 (b).

FIG. 13 is a diagram viewed from the direction of arrow A in FIG.

FIG. 14 is a diagram showing an example of a holding piece.

FIG. 15 is an explanatory sectional view for explaining a conventional ball screw device.

FIG. 16 is a view for explaining a ball circulation tube of a conventional ball screw device, (b) is a front view, (a) is a left side view of (b), and (c) is a right side surface of (b). It is a figure.

FIG. 17 is a plan view seen from above in FIG. 16 (b).

[Explanation of symbols]

2… Screw groove (rolling element rolling groove) 3 ... Screw shaft (guide shaft) 4 ... Screw groove (rolling element rolling groove) 5 ... Ball (rolling element) 6 ... Nut (movable body) 20 ... Ball circulation tube 20a, 20b ... Tube member 21 ... Convex portion (shift prevention means) 22 ... Recess (deviation prevention means) 60 ... Upper shift preventing member (shift preventing means) 61,71 ... Zama 62, 72 ... Flange part 70 ... Lower shift prevention member (shift prevention means) 100 ... Holding piece

Claims (4)

[Claims] 1. A guide shaft that has a rolling element rolling groove that extends in the axial direction and that extends in the axial direction, and a rolling element rolling groove that faces the rolling element rolling groove of the guide shaft. A movable body supported by the guide shaft so as to be relatively movable along the axial direction through rolling of a large number of rolling bodies inserted between the rolling bodies of these rolling bodies, and attached to the movable body. And a circulating tube for circulating the rolling elements rolling between the rolling elements between the rolling grooves infinitely, the circulating tube being constructed by joining a pair of half-divided tube members in a radial direction to each other. In the apparatus, a linear motion device characterized in that deviation preventing means for preventing deviation of the joint surfaces is provided between the joint surfaces of the pair of tube members. 2. The linear motion device according to claim 1, wherein the deviation preventing means is an uneven portion formed on each joint surface of the pair of tube members and fitted to each other. 3. A spacer, which is interposed between joint surfaces of the pair of tube members, and a shape which is integrally provided with the spacer and corresponds to an outer peripheral surface of the circulation tube. The linear motion device according to claim 1, wherein the linear motion device is a shift prevention member including a flange portion having. 4. The linear motion device according to claim 1, wherein a holding piece is provided between the rolling elements of the plurality of rolling elements.