JP2006125581A - Ball screw device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw device with a plurality of circuits arranged in one nut without more increasing the total length of a nut than required, preventing the interference of a circulation hole of the nut with a loading-zone screw groove adjacent thereto while holding an apparent scooping angle for a loading capacity. <P>SOLUTION: A ball circuit 32 in a circulating component 27 has a first curved portion R1 for guiding a ball scooped up from a spiral track by a tongue portion 30a of one leg 30 so as to be moved in the direction of the external side of the nut 24 approximately corresponding to the axial direction of the circulation hole 34, a second curved portion R2 for guiding the ball passing through the first curved portion R1 toward the other leg 20, a third curved portion R3 for guiding the ball passing through the second curved portion R2 via a body 31 toward the inside of the other leg 30, and a fourth curved portion R4 for guiding the ball passing through the third curved portion R3 to the position of the tongue portion 30a of the other leg 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ball screw device used in various machine devices such as machine tools and injection molding machines.

As a conventional ball screw device of this type, for example, the one shown in FIG. 5 (a) is known. In addition, in FIG. 5, the nut cross section of less than 1 volume is drawn for convenience of explanation.
In this ball screw device 1, a nut 6 having a helical thread groove 4 corresponding to the screw groove 2 is screwed onto a screw shaft 3 having a helical thread groove 2 on the outer peripheral surface.
The screw groove 4 of the nut 6 and the screw groove 2 of the screw shaft 3 are opposed to each other to form a spiral track that receives a load therebetween, and a large number of balls 5 as rolling elements are rolled on the spiral track. It is loaded movably. The nut 6 (or the screw shaft 3) is moved in the axial direction through the rolling of the ball 5 by the rotation of the screw shaft 3 (or the nut 6).

  Further, a part of the side surface in the circumferential direction of the nut 6 is a flat surface, and a pair of circulation holes 7 communicating with both the screw grooves 2 and 4 are formed on the flat surface in a direction substantially perpendicular to the axis of the nut 6. By drilling and fitting both ends of a tube-shaped circulation component 8 having a substantially U-shape into the pair of circulation holes 7 so as to straddle the screw shaft 3, along the spiral trajectory between the screw grooves 2, 4. A ball circulation path 9 is formed inside the circulation component 8 so that the revolving ball 5 is drawn up from one end of the circulation component 8 and guided to the outside of the nut 6 and returned to the spiral track from the other end. .

The circulation component 8 is fitted into the pair of circulation holes 7 of the nut 6 and has a pair of leg portions 8a formed with tongue portions 8c that scoop up the balls 5 at the tip, and a main body connecting the pair of leg portions 8a. 8b, and is divided into two in the radial direction along the central axis of the ball circulation path 9, and a circulation groove 9a constituting the ball circulation path 9 is formed on the divided surface.
Further, in order to realize smooth scooping of the ball 5, a resin circulation part (not shown) is divided into two parts in the same manner as described above, and inside the leg part of the circulation part fitted in the circulation hole 7 of the nut 6. There has also been proposed an arrangement in which the central axis of the circulation path is substantially coincident with the tangential direction of both screw grooves 2 and 4 and the lead angle direction (substantially coincident with the tangential direction of the spiral track) (see, for example, Patent Document 1). ).

However, since all the circulating parts are divided into two in the radial direction along the central axis of the ball circulation path 9, the tongue portion 8 c that scoops up the ball 5 is also divided, and the strength of the tongue portion 8 c is increased. There is concern about the decline.
Therefore, in order to avoid such division of the tongue portion, for example, a circulating component shown in FIGS. 6 and 7 has been proposed (see, for example, Patent Document 2).

  The circulating component 10 includes a pair of leg portions 11 that are fitted in a pair of circulation holes 7 of the nut 6 and have a tongue portion (not shown) that scoops up the ball 5 at the tip, and the pair of leg portions 11. A main body 12 to be connected, and the inner peripheral center lines of the pair of leg portions 11 are inclined in different directions with respect to the inner peripheral center line of the main body 12 so that the axis of the circulation path in the leg portions 11 A first arrangement including an inner circumference center line of one leg portion 11 and an inner circumference center line of the main body 12 can be arranged so as to substantially coincide with the tangential direction of the spiral track between the screw grooves 2 and 4. And the second dividing surface 14 including the inner circumferential center line of the other leg 11 and the inner circumferential center line of the main body 12 are different from each other in the radial direction through the step 16. It is divided into two in the radial direction so as to be symmetric, and the circulation circuit 10a constituting the ball circulation path 10a is formed on the divided surface. Groove 15 is formed.

In FIG. 7, reference numeral 18 denotes a center line of the ball circulation path 10a (inner circumference of the circulation component), and 19 denotes a ball center locus of the spiral orbit.
In the ball circulation path 10a in the circulation component 10, a total of two curved portions 17 each included in the first dividing surface 13 and the second dividing surface 14 are arranged, and FIG. Referring to FIG. 7 and FIG. 7, when the angle seen from the shaft center of the screw shaft 3 at the scooping point where the ball 5 is separated from the screw groove 2 of the screw shaft 3 is the apparent scooping angle θ, FIG. The circulating part 8, the circulating part disclosed in Patent Document 1 and the circulating part 10 shown in FIG. 6 have an apparent scooping angle θ of 0 °.

US Pat. No. 2,851,894 Japanese Patent Laid-Open No. 2003-232421

By the way, in order to increase the load capacity of the ball screw device, it is preferable that the apparent scooping angle θ described above is large. That is, referring to FIG. 5A and FIG. 5B, the apparent scooping angle θ is not 0 °, and the larger the number, the more balls 5 are subjected to load, which is advantageous in terms of load capacity. become.
However, if the apparent scooping angle θ is increased in the circulating component of Patent Document 3, the shape of the circulating component becomes complicated, and the circulating hole 7 into which the leg of the circulating component is fitted is enlarged. In the case of a ball screw device in which adjacent screw grooves are close to each other, such as a ball screw device having a small lead or a multi-threaded ball screw device, the thread groove in the load zone of the nut 6 adjacent to the circulation hole 7 is necessary. There is a concern that it may interfere with 4.

Further, when a plurality of circulation circuits are arranged in parallel to one nut 6, adjacent circulation parts and circulation holes 7 are likely to interfere with each other, and in order to avoid this interference, it is attempted to arrange the adjacent circulation circuits apart. There are problems such as an increase in the overall length of the nut 6 and an increase in the size of the apparatus.
The present invention has been made in order to eliminate such inconvenience, and it is possible to easily realize the scooping up of the ball in the direction substantially coinciding with the tangential direction of the spiral track. It is possible to prevent the nut circulation hole from interfering with the thread groove of the adjacent load zone while having an apparent scooping angle for obtaining one, and without increasing the total length of the nut more than necessary. It is an object of the present invention to provide a ball screw device including a circulating component in which a plurality of circulation circuits can be arranged on a nut.

In order to achieve the above object, the invention according to claim 1 is directed to a screw shaft having a spiral thread groove on the outer peripheral surface, and a spiral thread groove corresponding to the screw groove of the screw shaft on the inner peripheral surface. A nut that is screwed onto the screw shaft, a plurality of balls that are slidably loaded on the spiral track between the screw grooves, and the ball that rolls on the spiral track. Ball circulation that leads to the outside of the nut from one circulation hole of a pair of circulation holes drilled in a direction substantially perpendicular to the axis of the nut on the side surface in the direction, and returns to the spiral track from the other circulation hole In a ball screw device including a circulating component having both ends fitted to each circulation hole to form a path therein,
The circulation part is fitted in the circulation hole of the nut at both ends, and a tongue part that scoops up the ball rolling the spiral track at each end in a direction substantially coincident with the tangential direction of the spiral track. A pair of legs, and a main body connecting the pair of legs,
The ball circulation path in the circulation part is configured such that the traveling direction of the ball scooped up from the spiral track by the tongue portion of one leg portion of the pair of leg portions is a direction toward the outside of the nut. A first curved portion that guides in a direction substantially coincident with the axial direction of the circulation hole or has a predetermined angle, and the ball that has passed through the first curved portion is guided in the direction of the other leg portion. A second bending portion, a third bending portion that guides the ball that has passed through the second bending portion to the inside of the other leg portion through the main body, and the passage that has passed through the third bending portion. And a fourth curved portion for guiding the ball to the position of the tongue portion of the other leg portion.

The invention according to claim 2 is characterized in that, in claim 1, the shaft centers of the pair of circulation holes are spaced apart from each other by the same dimension in opposite directions from the axis of the screw shaft.
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the circulating component is divided into two or more along a substantially path direction of the ball circulation path at a position avoiding the tongue portions of the pair of legs. It is characterized by that.
The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein a dividing surface that divides a part or all of the leg portion of the dividing surface of the circulating component is the first curved portion. And / or substantially perpendicular to a plane including the center line of the ball circulation path in the fourth curved portion.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the ball circulation path in the circulating component is between the first curved portion and the second curved portion or each curved portion. And / or the axis of the screw shaft at the scooping point at which the ball leaves the spiral trajectory between the third curved portion and the fourth curved portion or at the inflection point of each curved portion. When the angle seen from the center is the apparent scooping angle θ, the angle formed by the ball traveling direction and the axis of the circulation hole is in the range of 0 ° or more and less than the apparent scooping angle θ. And
The invention according to claim 6 is characterized in that, in any one of claims 1 to 5, the circulation hole has a length dimension larger than a width dimension thereof.
The invention according to a seventh aspect is characterized in that, in the sixth aspect, the longitudinal direction of the circulation hole is arranged in a direction substantially along the thread groove.

  According to the present invention, the ball circulation path in the circulation component is such that the traveling direction of the ball scooped up from the spiral track by the tongue portion of one of the pair of legs is the direction of the outside of the nut, and By having the first bending portion (or the fourth bending portion) that leads in a direction that substantially coincides with the axial direction of the circulation hole or has a predetermined angle, the first bending portion (or the fourth bending portion) ), The circulation hole can be made smaller compared to the case where the portion is made linear, and this makes it possible to have an apparent scooping angle θ for obtaining a load capacity without increasing the circulation hole. .

  As a result, the ball can be easily picked up in a direction substantially coinciding with the tangential direction of the spiral trajectory, and the nut circulation hole is adjacent to each other while having an apparent scooping angle for obtaining a load capacity. It is possible to prevent interference with the thread groove of the load zone, and moreover, a plurality of circulation circuits can be arranged in one nut without making the total length of the nut unnecessarily long.

Further, the circulation part is divided into two or more along the substantially circular direction of the ball circulation path at a position avoiding the tongue parts of the pair of legs, thereby avoiding the division of the tongue part. Strength reduction can be prevented.
In this case, the dividing surface that divides part or all of the leg portions of the dividing surface of the circulating component is substantially the same as the plane including the center line of the ball circulation path in the first bending portion and / or the fourth bending portion. By dividing so as to be orthogonal, the circulating parts can be divided point-symmetrically. As a result, the circulating parts can be easily assembled by joining the same-shaped divided bodies, and the molds for the divided bodies Since only one type is required, the cost can be reduced.

  Further, the ball circulation path in the circulation component is between the first curved portion and the second curved portion, or an inflection point of each curved portion, and / or between the third curved portion and the fourth curved portion. Alternatively, at the inflection point of each curved portion, the angle formed between the moving direction of the ball and the axis of the circulation hole is in a range of 0 ° or more and less than the apparent scooping angle θ. The bending R can be made larger.

As a result, the centrifugal force of the ball when passing through the ball is reduced, so that wear and breakage of the circulating parts due to the centrifugal force can be prevented and the circulation of the ball itself can be made smoother.
Furthermore, the length of the circulation hole is made larger than its width dimension, and the longitudinal direction of the circulation hole is arranged in a direction substantially along the screw groove, so that a ball screw device having a small lead or a multi-thread ball screw Even in a ball screw device in which adjacent screw grooves are close to each other like the device, it is possible to prevent the circulation hole from interfering with the screw groove in the adjacent load zone.

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
1 is a plan view of a ball screw device as an example of an embodiment of the present invention, FIG. 2 is a right side view of FIG. 1, FIG. 3 is a perspective view showing a divided body of circulating parts, and FIG. It is a figure which shows a body, (a) is the figure seen from the flat surface direction of a nut, (b) is the figure seen from the arrow Y direction of (a), (c) was seen from the arrow X direction of (a). FIG. 4D is a diagram viewed from the axial direction of the screw shaft.

  As shown in FIGS. 1 and 2, a ball screw device 20, which is an example of an embodiment of the present invention, has a screw shaft 22 having a helical screw groove 21 on an outer peripheral surface and a screw groove 21 on an inner peripheral surface. A nut 24 having a corresponding spiral screw groove 23 is fitted, and the screw groove 23 of the nut 24 and the screw groove 21 of the screw shaft 22 face each other to form a spiral track that receives a load therebetween. is doing. A large number of balls 25 as rolling elements are slidably loaded in the spiral track, and the nut 24 (or screw shaft 22) rolls the balls 25 by the rotation of the screw shaft 22 (or nut 24). It moves in the axial direction.

  A flat surface 24 a is formed on a part of the side surface in the circumferential direction of the nut 24, and a circulating component 27 is fixed to the flat surface 24 a through a presser 28 by, for example, a set screw 29. The circulation component 27 includes a pair of leg portions 30 and a main body 31 that connects the pair of leg portions 30. The inside of the circulation component 27 is a ball circulation path 32, and is point-symmetric along the path direction of the ball circulation path 32. The divided body 27a (see FIG. 3) divided into two parts is joined to each other at the dividing surface, and a circulation groove 33 constituting a ball circulation path 32 is formed on the divided surface of the divided body 27a.

As a result, the circulating component 27 can be easily assembled by joining the two divided bodies 27a having the same shape, and the cost can be reduced because only one type of mold is required for the divided body 27a. In this embodiment, two circulation parts 27 are arranged to form two circulation circuits.
The pair of leg portions 30 are spaced apart from each other in the axial direction of the screw shaft 22 and spaced apart from each other in the radial direction of the screw shaft 22. There is provided a tongue portion 30a for scooping up the ball 25 rolling on the spiral trajectory in a direction substantially coincident with the tangential direction of the spiral trajectory.

These leg portions 30 communicate with a spiral track between the screw grooves 21 and 23 and are formed in a pair of circulation holes 34 drilled in a flat surface 24a of the nut 24 in a direction substantially perpendicular to the axis of the nut 24. It is mated. The pair of circulation holes 34 are arranged with their axial centers spaced apart from the axis of the screw shaft 22 by the same dimension in opposite directions. In addition, the escape part 35 (refer FIG. 3) is formed so that the front-end | tip of the leg part 30 by which the tongue part 30a of the division | segmentation body 27a of the circulation component 27 is not provided may not contact the screw shaft 22. FIG.
Then, by this circulating component 27, the ball 25 rolling on the spiral path between the screw grooves 21 and 23 is scooped up from one leg 30 and guided into the main body 31 outside the nut 24, and the other leg 30 An infinite circulation trajectory of the ball returning to the spiral trajectory is formed.

  Here, in this embodiment, the ball circulation path 32 in the circulation component 27 is formed on one leg 30 of the pair of legs 30 with reference to FIGS. 4 (c) and 4 (d). A first direction in which the traveling direction of the ball 25 scooped up from the spiral trajectory by the tongue portion 30a is the direction of the outer side of the nut 24 and substantially coincides with the axial direction of the circulation hole 34 or has a predetermined angle. The bending portion R1, the second bending portion R2 that guides the ball 25 that has passed through the first bending portion R1 in the direction of the other leg portion 30, and the ball 25 that has passed through the second bending portion R2 are the main body. A third bending portion R3 that leads to the inside of the other leg portion 30 through 31 and a fourth portion that guides the ball 25 that has passed through the third bending portion R3 to the position of the tongue portion 30a of the other leg portion 30. And a curved portion R4.

  Further, the circulation component 27 is divided into two symmetrically along the path direction of the ball circulation path 32 at positions avoiding the tongue portions 30a of the pair of leg portions 30, and specifically, FIG. 3 and FIG. Referring to FIG. 5, the divided surface A and the divided surface C that divide the leg portion 30 among the divided surfaces of the circulating component 27 (divided body 27a) are ball circulations in the first curved portion R1 and the fourth curved portion R4. It is divided so as to be substantially orthogonal to a plane including the center line of the path 32 (a plane including a normal line group of the center line of the ball circulation path 32 in each curved portion: a plane along the paper surface of FIG. 4C).

Hereinafter, a detailed description will be given with reference to FIGS. 3 and 4. In FIG. 4, reference numeral 40 denotes a ball scooping position of one leg, 41 a ball scooping position of the other leg, 42 an intermediate point of the ball circulation path 32, and 43 in the ball circulation path 32. A ball center locus 44 is a ball center locus in a spiral orbit (load zone).
First, with reference to FIG. 4, the ball circulation path 32 in the circulation component 27 will be described along the progression of the ball 25. Here, as shown in FIG. 4D, the screw shaft 22 is assumed to rotate clockwise as viewed from the direction of the axis.

The ball 25 rolling between the screw grooves 21 and 23 in the spiral orbit which is the load zone is rolled up in a substantially tangential direction of the spiral orbit by the tongue portion 30a at the ball lifting position 40 of one leg 30. Then, it deviates from the spiral trajectory and enters the ball circulation path 32.
Here, θ in FIG. 4D is an apparent scooping angle for obtaining a load capacity, and is in a range of 0 <θ ≦ 90 ° (substantially about 20 to 45 °).

The ball 25 that has entered the ball circulation path 32 from the ball scooping position 40 has a traveling direction substantially the same as the axial direction of the circulation hole 34 along the first curved portion R1 in the ball circulation path 32, that is, circulation. The direction of the component 27 is changed to the direction of the main body 31.
The ball 25 that passes through the first curved portion R1 and proceeds toward the main body 31 of the circulating component 27 changes its direction toward the other leg 30 by the second curved portion R2, and then the circulating component 27. Through the ball circulation path 32 in the main body 31 to the intermediate point 42 of the ball circulation path 32.

The circulation path from the intermediate point 42 of the ball circulation path 32 to the third curving portion R3 and the fourth curving portion R4 and the ball scooping position 41 of the other leg 30 is one ball scooping position 40. A point-symmetric shape of the path from the center point 42 of the ball circulation path 32 to the intermediate point 42.
In this way, the ball circulation path 32 in the circulation component 27 indicates the traveling direction of the ball 25 scooped up from the spiral track by the tongue 30a of one leg 30 of the pair of legs 30 on the outside of the nut 24. The first bending portion R1 (or the fourth bending portion) is provided by having the first bending portion R1 (or the fourth bending portion R4) that leads in a direction that substantially coincides with the axial direction of the circulation hole. Compared to the case where the portion R4) is linear, the circulation hole 34 can be made smaller, so that the apparent rise angle for obtaining the load capacity without unnecessarily increasing the circulation hole 34. can have θ.

  As a result, the scooping of the ball 25 in a direction substantially coinciding with the tangential direction of the spiral trajectory can be easily realized, and the nut 24 can be circulated while having an apparent scooping angle θ for obtaining a load capacity. It is possible to prevent the hole 34 from interfering with the thread groove 23 of the adjacent load zone, and furthermore, it is possible to arrange a plurality of circulation circuits in one nut 24 without making the entire length of the nut 24 longer than necessary. Can do.

  The traveling direction of the ball 25 after passing through the first curved portion R1 does not necessarily have to be a direction along the axis of the circulation hole 34, and the first curved portion R1 and the second curved portion R2 The angle formed between the traveling direction of the ball 25 and the axis of the circulation hole 34 at the inflection point of each of the bending portions and between the third bending portion R3 and the fourth bending portion R4 or at the inflection point of each bending portion. May be tilted so as to be in the range of 0 ° or more and less than the apparent scooping angle θ.

  Thus, by tilting the traveling direction of the ball 25 (the direction of the ball circulation path 32) at the time when the first bending portion R1 is finished with respect to the axis of the circulation hole 34 of the nut 24, the first bending portion R1. In addition, the bending radius R of the second curved portion R2 can be increased, thereby reducing the centrifugal force of the ball 25 when passing the ball, and preventing the circulating component 27 from being worn or damaged by the centrifugal force. In addition, the circulation of the ball 25 itself can be made smoother.

Further, the circulation hole 34 of the nut 24 may be a round hole, but it is a hole having a length dimension larger than the width dimension, such as an oval or an ellipse, and the longitudinal direction thereof is substantially the spiral track between the screw grooves 21 and 23. Desirably along the direction.
By using such a circulation hole 34, even in a ball screw device in which adjacent screw grooves 23 are close to each other, such as a ball screw device having a small lead or a multi-spindle ball screw device, the circulation hole 34 has Interference with the screw groove 23 can be prevented.

Next, a method of dividing the circulating component 27 that does not need to divide the tongue portion 30a while having the above-described ball circulation path 32 will be described.
As shown in FIG. 3 and FIG. 4A, the dividing surface of the circulating component 27 (divided body 27 a) includes the dividing surface A of one leg 30 including the end of the main body 31 and the end of the main body 31. This is expressed as a split surface C of the other leg 30 and a split surface B of the middle part of the main body 31.

  The dividing surface A is a plane including the center line of the ball circulation path 32 of the first curved portion R1 (a plane including a normal line group of the center line of the ball circulation path 32 in the curved portion R1: the paper surface of FIG. 4C). The surface along the surface). Thereby, the dividing surface A does not divide the tongue portion 30a, and the strength of the tongue portion 30a can be prevented from being lowered. The dividing surface C is a surface in contact with the dividing surface A when the two divided bodies 27a are joined point-symmetrically.

On the other hand, the dividing plane B is also a plane connecting the dividing plane A and the dividing plane C, and the dividing plane B may or may not include the center line of the ball circulation path 32 (in the illustrated example, the dividing plane B is a ball Although the center line of the circulation path 32 is not included), a part or all of the dividing plane B (all in this example) and the ball center locus 43 in the ball circulation path 32 are at an intermediate point 42 of the ball circulation path 32. Crossed.
The crossing angle here is less than 90 °, preferably 45 ° or less, and thereby, the ball splitting path B is joined at the joint surface between the split surfaces B when the two split bodies 27a are joined in a point symmetry. Can be suppressed as compared with the case where the crossing angle is 90 °, and the smooth rolling of the ball 25 can be ensured.

  In addition, when the tongue part 30a of one leg part has the shape which protruded from the division surface A, as shown in FIG.4 (d), it bends to the root of the tongue part 30a in the division surface A R50. May be provided. By this bending R50, the circulating component 27 can be divided without having a strong uneasiness around the tongue portion 30a. In this case, a bending R51 is also provided on the dividing surface C side so as not to interfere with the bending R50 of the dividing surface A.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, the circulating component 27 is fixed to the flat surface 24a of the nut 24 via the presser 28, but the circulating component 27 is fixed to the flat surface 24a of the nut 24 without using the presser 28. You may fix directly with a screw etc.
In addition, the thread groove, screw shaft, nut, ball, circulation hole, ball circulation path, circulation component, tongue portion, leg portion, main body, first bending portion, second bending portion, and the like exemplified in the above embodiment The material, shape, dimensions, form, number, location, etc. of the third curved portion and the fourth curved portion are arbitrary and are not limited as long as the present invention can be achieved.

It is a top view of a ball screw device which is an example of an embodiment of the invention. It is a right view of FIG. It is a perspective view which shows the division body of a circulation component. It is a figure which shows the division body of a circulation component, (a) is the figure seen from the flat surface direction of a nut, (b) is the figure seen from the arrow Y direction of (a), (c) is the arrow X of (a). The figure seen from the direction, (d) is a figure seen from the axial direction of the screw shaft. It is explanatory drawing for demonstrating the conventional ball screw apparatus, (a) is a figure where the apparent scooping angle (theta) is 0 degree, (b) is a figure where the apparent scooping angle (theta) is 0 degree <(theta). It is a disassembled perspective view which shows an example of the conventional circulation component. It is explanatory drawing for demonstrating the ball | bowl circulation path | route of the circulation component of FIG.

Explanation of symbols

20 Ball screw device 21 Screw groove 22 Screw shaft 23 Screw groove 24 Nut 25 Ball 27 Circulating component 30 Leg 30a Tongue 31 Main body 32 Ball circulation path 34 Circulation hole R1 First curved portion R2 Second curved portion R3 Third Curved portion R4 Fourth curved portion

Claims (7)

A screw shaft having a spiral thread groove on the outer peripheral surface, a nut having a spiral thread groove corresponding to the screw groove of the screw shaft on the inner peripheral surface and screwed onto the screw shaft; A large number of balls loaded so as to be able to roll on the spiral track between the thread grooves and the balls rolling on the spiral track in a direction substantially perpendicular to the axis of the nut on the circumferential side surface of the nut. One end of each of the pair of perforated holes is guided to the outside of the nut, and both ends are fitted to the respective circulating holes so as to form a ball circulation path that returns to the spiral track from the other circulation hole. In a ball screw device with combined circulating parts,
The circulation part is fitted in the circulation hole of the nut at both ends, and a tongue part that scoops up the ball rolling the spiral track at each end in a direction substantially coincident with the tangential direction of the spiral track. A pair of legs, and a main body connecting the pair of legs,
The ball circulation path in the circulation part is configured such that the traveling direction of the ball scooped up from the spiral track by the tongue portion of one leg portion of the pair of leg portions is a direction toward the outside of the nut. A first curved portion that guides in a direction substantially coincident with the axial direction of the circulation hole or has a predetermined angle, and the ball that has passed through the first curved portion is guided in the direction of the other leg portion. A second bending portion, a third bending portion that guides the ball that has passed through the second bending portion to the inside of the other leg portion through the main body, and the passage that has passed through the third bending portion. A ball screw device comprising: a fourth curved portion for guiding the ball to the position of the tongue portion of the other leg portion.   2. The ball screw device according to claim 1, wherein the shaft centers of the pair of circulation holes are spaced apart from each other by the same dimension in opposite directions from the axis of the screw shaft.   3. The ball according to claim 1, wherein the circulation component is divided into two or more along a substantially path direction of the ball circulation path at a position avoiding each tongue portion of the pair of leg portions. Screw device.   A plane including a center line of the ball circulation path in the first curved portion and / or the fourth curved portion, wherein a divided surface that divides a part or all of the leg portion among the divided surfaces of the circulating component. The ball screw device according to any one of claims 1 to 3, wherein the ball screw device is substantially orthogonal.   The ball circulation path in the circulation part is between the first bending portion and the second bending portion or at a turning point of each bending portion, and / or the third bending portion and the fourth bending portion. If the angle seen from the axial center of the screw shaft of the scooping point at which the ball separates from the spiral trajectory is an apparent scooping angle θ at the inflection point between each curved portion or each curved portion, the progression of the ball The ball screw device according to any one of claims 1 to 4, wherein an angle formed by a direction and an axis of the circulation hole is in a range of 0 ° or more and less than an apparent scooping angle θ.   The ball screw device according to any one of claims 1 to 5, wherein the circulation hole has a length dimension larger than a width dimension thereof.   The ball screw device according to claim 6, wherein a longitudinal direction of the circulation hole is arranged in a direction substantially along the screw groove.

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