JPH10196654A - Ball circulation tube for ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily cope with high speed operation of a ball screw by improving strength of a tongue of a ball circulation tube for capturing balls, without varying the basic size of a nut. SOLUTION: A half-cut tubular member 12 is produced first. Two members 12 are combined with each other to form one ball circulation tube for a ball screw. In such a circulation tube, the half-cut tubular member 12 is made of sintered metal which can be varied in thickness partially. A portion near a root of a tongue 11 for capturing the balls is particularly increased in its thickness for obtaining strength enough to resist pressure of collision of the balls. Other portions have ordinary thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball circulating tube for a ball screw, and more particularly to a ball screw circulating tube, which is provided at both ends of the tube to reinforce a tongue portion for scooping up and circulating a ball so as to cope with a high speed ball screw. Ball circulation tube.

[0002]

2. Description of the Related Art When a ball screw is driven, a number of balls roll and move in a spiral screw groove provided opposite a screw shaft and a nut. After the balls move a predetermined distance in the nut, they come off the thread groove,
The circulating motion of returning to the original position of the thread groove via the return path and rolling again in the thread groove is repeated. The ball circulation system includes a circulation tube, a circulation piece, and an end cap. Among them, the present invention is applied to a ball screw of a circulation tube system which is suitable for mass production and is advantageous in cost.

Conventionally, as a ball circulation tube, for example, as shown in FIG. 9, a pipe material is bent into a U-shape, and a tongue portion 11 for scooping up a ball at both ends thereof is formed (a first conventional tube). Examples) and a split-type press-formed tube as shown in FIG. 10 (second conventional example) are known. In the former, the tongue portions 11 are individually formed by machining such as milling. On the other hand, in the latter, a U-shaped ball circulation tube is divided into two by a symmetry axis in the tube axis direction, and a half-split divided tube member 12 having a tongue portion 11 on one end side in advance is formed by pressing a plate material. It is manufactured and assembled into one ball circulation tube by combining two sheets. Since the cross section of each divided pipe member 12 has a semicircular arc shape, it can be easily formed, is suitable for mass production, and is inexpensive.

[0004]

Recently, there has been a tendency to use ball screws at a high speed, and accordingly, the impact when the balls collide with the tongue portion 11 of the ball circulation tube has also become severe. As a result, damage due to insufficient strength of the tongue portion of the ball circulation tube is likely to occur, and it is necessary to improve the strength of the tongue portion as a countermeasure for speeding up the ball screw.

However, in the first and second conventional examples, if the thickness of the tongue portion 11 provided at the end of the tube is increased to improve the strength, the thickness of the entire ball circulation tube is reduced. Since the ball circulation tube must be thick, the size of the entire ball circulation tube increases. However, with the standard nut, as shown in FIG.
The outer diameter of the nut 3 adopts a "circumferential" dimension in which the ball circulation tube 7 fits within the nut circumference. for that reason,
If the size of the entire ball circulation tube becomes large, it will protrude outside the circumference of the standard nut. As a result, it is necessary to change the specifications such that the mating part, which should normally be fitted with the standard nut as it is, must be relieved so that it does not interfere with the ball circulation tube on the outer periphery of the protruding nut. There is a problem that they cannot respond immediately.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the conventional ball circulating tube which is caused when the ball screw is adapted to high speed operation. It is an object of the present invention to provide a ball screw circulating tube for a ball screw capable of high-speed operation, which can improve the strength of a tongue portion for picking up a ball of a tube without changing a standard size of a nut.

[0007]

In order to achieve the above object, the present invention relates to a ball circulating tube of a ball screw having a tongue portion at both ends for picking up the ball when guiding and circulating the ball. Is formed with a sintered metal, and the thickness of the tongue portion in the vicinity of the base is particularly thick.

The ball circulation tube is made of a sintered metal molded product, and the thickness of the portion near the base of the tongue portion is thickened to give sufficient strength to withstand high-speed use. Thinner to reduce the size of the entire ball circulation tube, allowing the use of standard size nuts. This makes it possible to immediately respond to a request for high-speed use of the ball screw.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding parts as those in the related art are denoted by the same reference numerals.

FIG. 1 to FIG. 5 show an embodiment of a divided type sintered metal ball circulation tube according to the present invention, FIG. 1 is a plan view of a ball screw, and FIG. 2 is a cross-sectional view thereof. FIG. 3 is a front view of a half-split tube member of a ball circulation tube, and FIG. 4 is a side view of a ball circulation tube in which two differently-split tube members are combined. FIG. 5 and FIG. 5 are enlarged views of the tongue portion.

First, the overall structure of a circulating tube type ball screw will be described with reference to FIGS. 1 and 2. The screw shaft 1 is a shaft member having a spiral groove 2 having an arc-shaped cross section on its outer surface. The nut 3 is a cylindrical member having a spiral groove 4 on the inner surface corresponding to the spiral groove 2 of the screw shaft, and two holes opened to the spiral groove 4 are formed in a plane portion 5 formed on a part of the outer periphery. ing. The ends of the U-shaped ball circulation tube 7 are fitted into the holes of the nut. The ball circulation tube 7 is fixed to the nut flat portion 5 via a mounting plate 9 by a set screw 8.

The screw shaft 1 inserted through the inner hole of the nut 3
The spiral groove 2 is opposed to the spiral groove 4 of the nut, and a ball circulation path including a ball circulation tube 7 provided in the nut 3 and the spiral groove 4 between both ends of the ball circulation path.
, A number of balls 10 are rotatably arranged. These balls 10 fit into the spiral groove 4 of the nut and the spiral groove 2 of the screw shaft without any gap, and the nut 3 and the screw shaft 1 can be relatively spirally moved through the rolling of the ball 10 in the axial direction. ing.

Due to the relative helical movement of the nut 3 and the screw shaft 1, the ball 10 rolls along the helical grooves 2 and 4, and collides with the tongue 11 formed at the end of the ball circulating tube 7, and the helical groove At the same time as being scooped up from the tubes 2 and 4, it is guided into the ball circulation tube 7, passes through the tube, and returns to the space between the spiral grooves 2 and 4 from the opposite end.

The ball circulating tube 7 is of a split type, and the split pipe member 1 is divided into two parts by a symmetric axis in the pipe axis direction.
2, 12 (one divided pipe member 12 is shown in FIG. 3). Each divided pipe member 12 of this embodiment has a tongue portion 11 only at one end side, and the other end side is a cut-out end 13. The tongue portion 11 is formed at a position slightly shifted outward from the dividing surface 14, and a portion A near the base of the tongue portion 11 (in this embodiment, including the base itself of the tongue portion 11 and about the center thereof) The portion corresponding to a semicircle) has a particularly large thickness as shown in FIGS. 3 to 5, and the impact of the collision of the ball 10 rolling at high speed along the spiral grooves 2 and 4 is obtained. To be able to withstand enough. However, the thickness of the portion other than the vicinity of the base of the tongue portion 11 is the same as that of the conventional standard size ball circulation tube.

The divided pipe member 12 is formed by sintering. That is, in the conventional integrated ball circulation tube or the press-formed divided ball circulation tube, it is not possible to increase the thickness of only a part like the vicinity of the base of the tongue portion. You.

This embodiment was processed under the following molding conditions. Kind of metal powder: Stainless steel Binder: Resin Molding temperature, Molding pressure: Almost the same as that of ordinary resin.
The ends 2 and 12 are joined by the dividing surface 14, and the ends are fitted into two holes of the nut, and are fixed to the flat portion 5 of the nut via the mounting plate 9 by the set screw 8.

Thus, the ball circulation tube 7 of the present invention
Can be easily formed by sintering with powder metallurgy technology, and can be manufactured at low cost because specially advanced equipment and technology are not required to make only a part thick.

Moreover, the thickness of the tongue portion 11 near the base of the tongue portion 11 for scooping up the ball 10 rolling at high speed is increased to ensure sufficient strength to withstand an impact, while the thickness of the other portions is reduced to a standard size. it can. Therefore, by simply changing the diameters and shapes of the two holes for inserting the ball circulation tube 7 opening in the flat portion 5 of the nut 3, a conventional standard-sized ball screw can be used. There is no need to consider the interference between the parts and the ball circulation tube 7, and a very large effect can be achieved in practical use, which can easily meet the needs for high-speed use of the ball screw.

Further, since the ball circulation tube of the ball screw of the present invention is a sintered molded product, it is easy to change the material of the sintered metal powder as a raw material, and if necessary, a material having a higher strength is used. Can be easily commercialized and provided.

FIG. 6 shows a second embodiment of the present invention. The ball circulation tube 7A has a portion near the root of the tongue portion 11 thicker than other portions and a portion of the tongue portion 11 where the ball 10 directly collides (collision portion).
The first point is that the tip 20 made of a particularly high-strength metal such as quenched steel is embedded and formed.
Is different from the embodiment. In this case, the impact of the collision of the ball 10 can be received by the thickness near the base of the tongue portion 11, and wear and indentation of the collision portion due to the direct collision of the ball 10 can be prevented by the high hardness chip 20. .

The other constructions and functions and effects are the same as those of the first embodiment. 7 and 8 show a third embodiment of the present invention. This ball circulation tube 7B
The thickness of the portion B near the root of the tongue portion 11 (in the case of this embodiment, the portion of the entire circumference of the tube end including the root itself of the tongue portion 11) is thicker than the other portions over the entire circumference of the tube end. The point that it is formed is different from the first embodiment. According to this embodiment, the strength of the tongue portion 11 for receiving the impact of the collision of the ball 10 is the first.
Since the shape of the two holes for inserting the ball circulation tube 7B opening in the flat portion 5 of the nut 3 may be circular, it is sufficient to only increase the hole diameter through a drill, and the nut is There is an advantage that drilling is simple and it is possible to more easily cope with high speed.

Furthermore, since the entire circumference of the tube end is made thick, there is an advantage that the ball 10 is hardly vibrated by the collision of the ball 10 and the stability of the circulation operation is high. The other configuration and operation and effect are the same as those of the first embodiment.

[0023]

As described above, according to the ball circulation tube of the ball screw of the present invention, the strength of the tongue portion at the end of the ball circulation tube can be increased without changing the outer diameter of the standard size nut. Therefore, it can be applied to all existing circulating tube type ball screws, and as a result, it is possible to easily cope with the high speed of the circulating tube type ball screw without changing the basic specifications. This has a large practical effect.

[Brief description of the drawings]

FIG. 1 is a plan view of a ball screw according to the present invention.

FIG. 2 is a cross-sectional view of FIG. 1, in which a ball circulation tube has a cross-section along a ball passage for easy understanding of ball circulation.

FIG. 3 is a front view of a divided tube member of the ball circulation tube according to the first embodiment of the present invention.

FIG. 4 is a side view of a ball circulation tube in which two divided pipe members are combined, as viewed in the direction of arrow IV in FIG. 3;

FIG. 5 is an enlarged view of a tongue portion of the ball circulation tube of FIG. 4;

FIG. 6 is a front view of a divided tube member of a ball circulation tube according to a second embodiment of the present invention.

FIG. 7 is a front view of a divided tube member of a ball circulation tube according to a third embodiment of the present invention.

FIG. 8 is a side view of a ball circulation tube in which two divided pipe members are combined, as viewed in the direction of arrow VIII in FIG. 7;

FIG. 9 is an arrow view of a conventional integrated ball circulation tube.

FIG. 10 is a front view of a split pipe member of a conventional split-type press-formed ball circulation tube.

FIG. 11 is an explanatory view of a conventional circular circulating tube type standard ball screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw shaft 2 Spiral groove 3 Nut 7 Ball circulation tube 7A Ball circulation tube 7B Ball circulation tube 10 Ball 11 Tongue part 12 Split pipe member

Claims (1)

[Claims] 1. A ball circulation tube of a ball screw having at both ends a tongue portion for picking up the ball when guiding and circulating the ball, wherein the ball circulation tube is formed of a sintered metal, and near a root of the tongue portion. A ball circulation tube for a ball screw, wherein the thickness of the portion is particularly thick.