JPH0637227Y2 - Ball circulation path in ball screw - Google Patents

Description

[Detailed Description of the Invention] a) Field of Industrial Application The present invention relates to an improved creation of a ball circulation path in a ball screw.

(B) Conventional Technology The following methods have been conventionally known as ball circulation paths in ball screws.

(1) Two rising holes corresponding to the screw groove position of the screw shaft are formed on one side of the nut so as to intersect the axis line, and an inverted U-shaped return tube is inserted into this hole to attach the ball to the screw shaft. A return tube system in which the ball is circulated in a tangential direction to circulate and move the ball (for example, as a publicly known material, "Precision Positioning Technology", page 53 or less, edited by Minoru Izawa, published by the Industrial Research Institute Co.

(2) A piece method in which a thread adjacent to the nut is partially cut off and a piece provided with an S-shaped groove is fitted to circulate a small number of balls in one rotation (same as above).

(3) By forming two rising holes corresponding to the screw groove positions of the screw shaft on one side of the nut, intersecting the axis, inserting a guide tube, and further providing a guide plate for circulation, Guide plate method (same as above) that circulates the balls by squeezing them up in the tangential direction of the screw shaft.

(4) Two rising holes corresponding to the screw groove position of the screw shaft are formed on one side of the nut in parallel with the axis, and a guide tube with a part of the tip cut off is inserted into this hole. A method described in Japanese Utility Model Publication No. 58 33945 relating to the previous invention of the inventor of the present application, in which the ball is circulated along the diameter of the screw shaft by providing a circulating ball follower.

C) Problems to be Solved by the Invention However, each of the above methods has the following problems, and improvement thereof has been desired.

First, in each of the above methods (1), (3), and (4), the ball is hiccuped by a tube. However, this type of tube lacks the strength of the hiccup point, and the ball screw There is a problem that it is not possible to cope with the speeding up of the movement, and particularly in the method (4), there is a possibility that the hiccup portion of the guide tube may be broken by the ball colliding at high speed because the ball is hiccuped in the diameter direction of the screw shaft.

In addition, the above methods (1) and (3) are for hiccuping the ball in the tangential direction of the screw shaft, but for this reason, the cutting surface of the nut for forming the rising hole becomes unnecessarily large. was there.

On the other hand, in the above method (2), since the tops are fixed to the nut one by one by adhesion, there is a problem that the manufacturing process is troublesome.

D) Means for Solving the Problems The present invention is intended to provide a circulation path that solves the above-mentioned problems of the prior art, and has the following configuration.

That is, in the circuit according to the present invention, the outside of the nut is cut off parallel to the axis of the nut, and two rising holes are formed at corresponding positions on the thread groove which is the cut surface and is separated by a predetermined number of leads. It is characterized in that a nest having the structure (a) described below is fitted into the rising hole, and upper ball entrances and exits of the nest are connected by a ball gap. (A) It has a plane longitudinal shape, and has a shape having an engaging brim to be engaged with a return hole of a nut on the upper portion, and a ball entrance / exit for communicating internally is provided on the side portion and the upper portion, and is provided on the side portion. Nesting in which the lower edge of the ball entrance / exit is formed into a slope surface on which the ball should run up.

Therefore, according to this invention, the ball rolling in the thread groove runs up the slope surface of the ball entrance / exit on the nest side, and is guided to the communication path inside the nest as it is from the ball entrance / exit above the nest. A series of circulation is made by entering the bottleneck, entering the other nest through the ball trail from the upper ball entrance and exit, running down the slope surface of the ball entrance on the nest side and reentering the thread groove. Achieve the action.

F) Embodiment Next, a specific embodiment of the present invention will be described with reference to the accompanying drawings.

A screw shaft 1 having a thread groove 2 suitable for ball movement engraved on the peripheral side, and a nut 3 having a thread groove 4 suitable for the screw shaft 1 engraved on the inner peripheral side are provided between the thread grooves 2 and 4. A large number of balls B are housed in and combined with each other, and the outside of the nut 3 is cut parallel to the axis of the nut 3 to obtain a flat cut surface 5.

Then, two rising holes 6 are formed along the axial direction in which the inserts 7 to be described below are to be fitted at corresponding positions on the thread groove 4 which are separated by a predetermined number of leads as the cut surface 5.

On the other hand, the insert 7 has a flat longitudinal shape (which is an ellipse in this embodiment) that matches the rising hole so as not to rotate in the rising hole 6, and has an engaging brim 7a ( (Provided on both short sides in this embodiment).

Reference numeral 7a in the drawing denotes an engagement step portion provided in the rising hole 6 for dropping the engagement flange 7a.

Further, ball entrances and exits 8a and 8b are opened at the side and the top of the insert 6, respectively, and these entrances and exits are communicated by the communication passage 8.

The lower edge of the side ball entrance / exit 8a is formed into a sloped surface 9 which has a tip end in an edge shape so as to run up the ball B, draws a curved surface, and rises in sequence.

The shape of the sloped surface 9 is preferably such that the ball B can easily run up, but in this embodiment, the radius of the curved surface is matched with the diameter of the ball to fulfill its function.

The upper and lower ball entrances / outlets 8b of the nests 6 and 6 are connected to each other by a ball channel, but in this embodiment, the return tube 10 constitutes a ball channel.

That is, the boss 7b is erected on the peripheral edge of the ball entrance / exit 8b in the upper part of the nest, and the step portion at the tip of the return tube 10 is fitted onto the boss 8b.

Reference numeral 11 in the figure denotes a return tube retainer for fixing the return tube 10 to the nut 3.

In addition, in the above embodiment, the insert 7 is integrally formed by casting, for example, by the lost wax method. However, the insert 7 may be formed by cutting into two pieces.

Further, it goes without saying that the form of the ball tunnel may be formed by the return tube as in this embodiment or by a split metal fitting such as the above-mentioned No. 58 33945.

G) Effect of the invention The invention configured as described above has the following effects.

(1) Since a nest is adopted for hiking the ball, unlike the tube, it is possible to increase the wall thickness of the part where the ball abuts during hiking (called the slope surface in this invention). It is possible to maintain sufficient strength no matter how small the unit is, or even at high speeds.

(2) For the same reason, the shape of the part where the ball abuts during hiccup can be set to an optimum shape that allows the ball to easily move.

(3) For the same reason, the ball can be hiccuped sufficiently smoothly without hiccuping the ball in the tangential direction of the screw shaft. Therefore, when the rising hole into which the insert is inserted is arranged along the axial direction of the nut. It can be done and the cutting surface of the nut is small.

(4) For the same reason, the integral winding is realized, and the fall of the nut when the thrust load acts on the ball screw is completely prevented.

(5) Since the insert, which has a longitudinal shape in the plane and is provided with an engaging flange at the top, is fitted into the rising hole, high accuracy can be obtained without the risk that the insert will rotate or move in the falling direction once fitted. .

(6) In the above case, if the insert is inserted by the press-fitting means, the processing accuracy is further enhanced, and if the insert is held down by the return tube as in the embodiment, there is an advantage that the assembly process becomes extremely easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a ball screw in which the ball circulation passage of the present invention is implemented, FIG. 2 is a perspective view of a nest forming the ball circulation passage of the present invention, and FIG. 3 is a ball circulation passage of the present invention. FIG. 4 is a plan view of a ball screw for carrying out the above, FIG. 4 is a plan view with the return tube removed, and FIG. 5 is a sectional view of the insert. In the figure, reference numeral (1) ... screw shaft (2) ... screw groove (3) ... nut (4) ... screw groove (5) ... cut surface (6) ... rising hole (7) ... … Nesting (7a) …… Engagement collar (8)… Communication passageway (8a) …… Ball entrance / exit (8b)… Ball entrance / exit (9) …… Slope surface (10) …… Return tube (B) …… ball

Claims (3)

[Scope of utility model registration request] 1. A screw shaft formed by engraving a thread groove suitable for movement of a ball on the peripheral side, and a nut formed by engraving a thread groove adapted for this screw shaft on the inner peripheral side, between the two thread grooves. In a ball screw in which a large number of balls are housed in a combination, the outer side of the nut is cut off in parallel with the axis of the nut, and a rising hole is formed at the corresponding position on the thread groove separated by a certain number of leads as this cut surface. A ball circulation path in a ball screw, characterized in that two holes are formed, a nest having the structure of (a) below is inserted into the rising hole, and the upper ball entrances and exits of the nest are connected by a ball trail. (A) It has a plane longitudinal shape, and has a shape having an engaging brim to be engaged with a return hole of a nut on the upper portion, and a ball entrance / exit for communicating internally is provided on the side portion and the upper portion, and is provided on the side portion. Nesting in which the lower edge of the ball entrance / exit is formed into a slope surface on which the ball should run up. 2. The ball circulation path in a ball screw according to claim 1, wherein the ball follow-up path is constituted by a return tube, and a boss to which the return tube is fitted is provided at the periphery of the ball entrance / exit provided in the upper part of the insert. 3. The ball circulation path in a ball screw according to claim 1, wherein the curvature of the slope surface of the nest is set to a curvature corresponding to the diameter of the ball.