JPH10205603A - Ball circulation tube for ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength of a tongue part without interfering with a thread groove adjacent to the thread groove of a part for scooping up a ball of a nut by thinning the thickness of at least one part other than the tongue parts of both end parts of a ball circulating tube more than that of a raw material of the ball circulating tube. SOLUTION: A ball circulating tube 7 is made of a tube raw material of a circular cross section, a plane part 12 is arranged in the vicinity of both end parts other than a tongue part 11, and the thickness t' of the plane part 12 is thinned more than the thickness (t) of the raw material. The size of a part where the plane part 12 formed in the vicinity of both end parts of the ball circulating tube 7 is inserted, is formed smaller than the size of a part where its circular arc part is inserted, and the distance between ball grooves which are adjacent to each other is formed larger than the distance of a case not having the plane part 12. Even if the thickness of the raw material is thickened for improving the strength of the tongue part 11, the ball circulating tube 7 is not interfered with a thread groove adjacent to the thread groove of a part where the ball of a nut is scooped up.

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. The present invention is applied to a circulation tube type ball screw which is suitable for mass production and is advantageous in cost. Conventionally, as a ball circulation tube, for example, as shown in FIG. 8, a tube material is bent into a U-shape, and a tongue portion 11 for scooping up a ball is formed at both ends (first conventional example). A split type press-formed tube as shown in FIG. 9 (second conventional example) is 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.

[0003]

In recent years, the use of ball screws has been increasing at a high speed, and with this, the impact when the ball collides with the tongue portion 11 of the ball circulation tube has 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, the first and second
In each of the conventional examples, when the thickness of the tongue portion 11 provided at the end of the tube is increased in order to increase the thickness, the thickness of the entire ball circulation tube must be increased. In some cases, the ball circulation tube may interfere with the screw groove adjacent to the screw groove of the portion where the ball of the nut is picked up, and it is necessary to make the ball circulation tube thick enough to avoid this interference. Therefore, there is a problem that the strength of the tongue portion becomes insufficient, and it is not possible to cope with an increase in the speed of the ball screw. The present invention has been made to solve the problems of the conventional ball circulation tube that occurs when the ball screw is adapted to high speed, and the purpose thereof is to provide a ball circulation tube, An object of the present invention is to provide a ball circulation tube of a ball screw in which the strength of a tongue portion for scooping up a ball of a ball circulation tube is improved without interfering with a thread groove adjacent to a thread groove of a portion for scooping up a ball of a nut.

[0004]

Means for Solving the Problems Since the ball screw can be used at a high speed if the strength of the tongue portion and the base of the tongue portion is secured, the above object can be achieved. In the ball circulation tube of a ball screw having a tongue portion at both ends for scooping up the ball when guiding and circulating the ball, in the vicinity of both end portions of the ball circulation tube, the thickness of at least a part other than the tongue portion is set to the thickness. It is characterized in that it is thinner than the material thickness of the ball circulation tube.

[0005]

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. First, the overall configuration 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 screw groove 2 having an arc-shaped cross section on its outer surface. The nut 3 is a cylindrical member having a screw groove 4 on the inner surface corresponding to the screw groove 2 of the screw shaft. Two holes 6 opening to the screw groove 4 are formed in a flat portion 5 formed on a part of the outer periphery. Have been. 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 flat portion 5 of the nut by a set screw 8 via a mounting plate 9. The screw shaft 1 inserted into the inner hole of the nut 3 has its thread groove 2 opposed to the thread groove 4 of the nut, and a ball circulation path composed of a ball circulation tube 7 provided in the nut 3 and its ball circulation path. The thread groove 4 between both ends of the
0 is arranged so that it can roll freely. These balls 10
The nut 3 and the screw shaft 1 are fitted into the screw groove 4 of the nut and the screw shaft 2 of the screw shaft without any gap, and the nut 3 and the screw shaft 1 are relatively helically movable in the axial direction through the rolling of the ball 10. Due to the relative helical movement of the nut 3 and the screw shaft 1, the ball 10 is
4 and collides with one of the tongue portions 11 formed at the end of the ball circulation tube 7 and is scooped up from the screw grooves 2 and 4 and is simultaneously guided into the ball circulation tube 7. Screw grooves 2 and 4 from the opposite end through
Repeat the cycle of returning between.

As shown in FIGS. 3, 4 and 5, the ball circulating tube 7 is made of a tube material having a circular cross section and has flat portions 12 near both ends other than the tongue portion 11. The thickness t 'is determined by the material thickness t of the ball circulation tube 7.
Thinner than As shown in FIG. 6 and FIG. 7, the inside of the hole 6 (only one is shown) into which both ends of the ball circulation tube 7 of the nut 3 are inserted, the end of the ball circulation tube 7 fits without gap. The ball circulation tube 7 is machined to have the same shape as the outer shape of the end portion of the ball circulation tube 7 excluding the tongue portion 11 so that it can be inserted.

At this time, the dimension D 'of the portion where the flat portion 12 near both ends of the ball circulation tube 7 is inserted is smaller than the dimension D of the portion where the arc portion of the ball circulation tube 7 is inserted, Distance to the ball groove 13
Is the adjacent ball groove 13 when the flat portion 12 is not provided.
Is greater than the distance m.

Therefore, even if the thickness of the tube material is increased in order to improve the strength of the tongue portion 11, the ball circulation tube 7 scoops up the ball of the nut 3 as compared with the conventional example. Interference with the thread groove 13 adjacent to the thread groove of FIG.

The present invention can be applied to a case where the ball circulation tube 7 is of a split type shown in FIG.

Although the embodiment has been described with reference to a ball screw having one ball circulation tube 7, the present invention can be applied to a ball screw having two or more ball circulation tubes 7.

[0011]

As described above, according to the ball circulating tube of the ball screw of the present invention, the ball circulating tube does not interfere with the thread groove adjacent to the thread groove of the portion for picking up the ball of the nut. Increase the thickness of the part,
As a result, the strength of the tongue portion can be improved, and as a result, it is possible to cope with high-speed use of the circulation tube type ball screw device.

Further, even when a ball having a large outer diameter is used in order to increase the load capacity of the ball screw, the ball circulation tube does not interfere with the screw groove adjacent to the screw groove of the portion for scooping up the ball of the nut. This has the effect.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a front view of one embodiment of the ball circulation tube of the present invention.

FIG. 4 is a bottom view of FIG. 3;

FIG. 5 is a perspective view of an end of the ball circulation tube of FIG. 3;

FIG. 6 is a partial view of the nut 3 of FIG.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a perspective view of a conventional integrated ball circulation tube.

FIG. 9 is a front view of a divided tube member of a conventional divided-type ball circulation tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw shaft 2 Screw groove 3 Nut 4 Screw groove 5 Flat part 6 Hole 7 Ball circulation tube 8 Set screw 9 Mounting plate 10 Ball 11 Tongue part 12 Split pipe member 13 Ball groove

Claims (1)

[Claims] 1. A ball circulation tube of a ball screw having at both ends a tongue portion which scoops up the ball when guiding and circulating the ball, wherein at least a part of the meat other than the tongue portion is located near both ends of the ball circulation tube. A ball circulation tube for a ball screw, wherein the thickness is smaller than the material thickness of the ball circulation tube.