JP2007225032A - Ball circulation member and ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent or suppress the pickup part of a ball circulation member from being damaged even when the pickup part is brought into contact with the ball rolling groove of a screw shaft. <P>SOLUTION: This ball screw comprises the screw shaft 12 having a clearance groove 9 in the ball rolling groove 11. A nut having a ball rolling groove in the inner peripheral surface is fitted onto the screw shaft. A plurality of balls are disposed in a ball track passage formed between these both ball rolling grooves. The ball screw further comprises a side cap (ball circulation member) having the pickup part 24 for picking up the balls in the ball track passage from one side and a ball circulation passage 27 for returning the balls 15 picked up by the pickup part 24 from the other side into the ball track passage. The pickup part 24 has, at the other part, the part having a distance in the deflecting direction shorter than that at the boundary part 9b between the ball rolling groove 11 and the clearance groove 9 within the range facing the ball rolling groove 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ball screw used in various industrial machines.

  The ball screw has a screw shaft 12 having a spiral ball rolling groove 11 on the outer peripheral surface, for example, like a ball screw 101 shown in FIG. A nut 14 having a spiral ball rolling groove 13 corresponding to the ball rolling groove 11 of the screw shaft 12 on the inner peripheral surface is fitted to the screw shaft 12. Here, the ball rolling groove 13 of the nut 14 and the ball rolling groove 11 of the screw shaft 12 are opposed to each other to form a ball raceway 8 between them. A plurality of balls 15 as a moving body are loaded so as to be able to roll, and further, a ball circulation member 171 for scooping up the balls 15 from the ball raceway 8 and circulating them infinitely is provided.

  Conventionally, however, the ball circulating member 171 as illustrated in the figure is formed by machining a scooping portion 124 for scooping up the ball 15 from the ball raceway 8 after bending a metal pipe into a substantially U shape. It is cut and produced. This type of ball circulating member has a scooping angle (an angle indicated by the symbol θ in the figure) in order to scoop up the ball so as not to interfere with the shoulder portion of the spiral ball rolling groove of the shaft. It is designed to crawl up at different positions. Therefore, in this type of ball circulation member, a step or a change in angle (crawl angle, lead angle) occurs at the joint between the scooping portion 124 and the ball rolling groove 11. Therefore, there is room for improvement in ensuring a smooth circulation of the balls 15.

  Therefore, in recent years, in the ball screw, as the ball circulation member, in order to ensure a smooth circulation of the ball, that is, the ball rolling on the spiral ball raceway is smoothly guided into the ball circulation member, and the ball circulation member In order to smoothly return the ball moving in the ball track to the ball track, the ball is picked up in the tangential direction of the ball track, and returned to the ball track from the tangential direction of the ball track. (For example, refer to Patent Document 1).

In the technique described in Patent Document 1, a so-called side cap type ball screw is disclosed.
Here, FIG. 12 shows an example of the ball circulation member 170 in this type of ball screw 100. In this example, the ball circulation member 170 is configured by combining two ball circulation member constituting members 230 as shown in FIG. 13, for example. The scooping portion 240 scoops up the ball in a tangential direction at a scooping point on the ball rolling groove.

On the other hand, the nut 14 is provided with a ball circulation member 170 mounting surface on the outer peripheral surface thereof, and the ball circulation member mounting surface is connected to the ball raceway 8 as shown in FIG. A long hole 20 is drilled. And the leg part 190 of the both ends of the ball | bowl circulation member 170 is engage | inserted by this long hole 20, respectively.
In this type of ball circulation member, the scooping portion scoops up the ball in the tangential direction at the scooping point on the ball rolling groove, so that the ball can be scooped up smoothly. Therefore, since the impact force when the ball collides with the scooping portion or other parts is weakened, it is possible to realize high speed and low noise.
JP 2005-83519 A

  By the way, in this kind of ball circulation member, as mentioned above, the scooping-up portion scoops up the ball in the tangential direction, so that the path through which the scooped-up ball circulates is somewhat complicated. Therefore, the processing cost is reduced by molding this type of ball circulation member by molding a resin. Further, if the ball circulation member is molded from a resin, there is an advantage that a portion where strength on the structure is required (for example, a thickness in the spiral direction of the scooping portion) can be set to a desired thickness.

However, since this type of ball circulating member scoops up the ball substantially in the tangential direction, the scooping portion 240 faces the ball rolling groove side of the screw shaft as illustrated in FIG. And projecting in a tongue shape. Therefore, the tip end portion 240s of the scooping portion 240 is thin.
In other words, the scooping portion in this type of ball circulation member is formed along a path to be scooped up in the tangential direction from the spiral ball rolling groove, so that the tip portion has a very acute angle. Actually, the tip does not just have an acute angle, but it is somewhat rounded, but it is desirable to lengthen the scooping part for smooth scooping of the ball. The tip of the scooping part cannot be thinned.

  In addition, the scooping part usually has a certain gap between the scooping part and the ball rolling groove of the screw shaft, and is set so that they do not contact each other in the normal rotation state of the ball screw. The This is because the scooping part relaxes the impact force of the ball on the scooping part when scooping the ball in the tangential direction, or takes into account, for example, the expansion of the material due to temperature change.

  For example, when a ball having a relatively large diameter is used, depending on the behavior of the ball (for example, rapid acceleration / deceleration of the ball, clogging of the ball, etc.), as shown in FIG. However, a relatively large force F may be applied (in the figure, an image in which the force F is applied is indicated by an arrow). In such a case, the scooping portion 240 cannot support the applied force F only by the rigidity of the resin material, and there is a possibility that damage such as breakage may occur.

  Therefore, the inventor of the present application has found that in this type of resin ball circulation member, the scooping portion and the ball rolling groove of the screw shaft are formed by deformation caused by applying a relatively large force F to the scooping portion. The scooping portion is flexed (elastically deformed) by the force F applied to the scooping portion, assuming contact, and the scooping portion and the ball rolling groove of the screw shaft are intentionally contacted (line contact or It was considered that the scooping-up portion was supported from the back (hereinafter also referred to as “backup”) by the ball rolling groove of the screw shaft. Thereby, even when a certain large load is applied to the scooping portion, excessive deformation of the scooping portion is prevented or suppressed, so that damage such as breakage of the scooping portion can be prevented.

However, as shown in FIG. 15, the ball rolling groove 11 of the screw shaft 12 has a relief groove for grinding relief in the bottom part of the ball rolling groove 11 in order to reduce grinding resistance when grinding. It is normal to add 9. Therefore, as illustrated in FIG. 16, when the scooping portion 240 is backed up by the ball rolling groove 11, the scooping portion 240 is located at the boundary portion 9 b between the ball rolling groove 11 and the escape groove 9 of the screw shaft 12. The back surface (the surface facing the ball rolling groove 11) is pressed. As a result, for example, as shown in FIG. 17, a notch-shaped crease (scratch) K is attached to the back surface of the resin scooping portion 240. And when such a wrinkle arises, there exists a possibility that the scooping-up part may be damaged on the basis of the wrinkle.
Therefore, the present invention has been made paying attention to such a problem, and even when the scooping portion of the ball circulating member and the ball rolling groove of the screw shaft are in contact with each other, the scooping portion has a wrinkle. An object of the present invention is to provide a ball circulation member and a ball screw that can prevent or suppress sticking.

In order to solve the above-mentioned problems, the present invention is directed to a screw shaft having a ball rolling groove on the outer peripheral surface and a relief groove formed in the ball rolling groove, and facing the outer peripheral surface of the screw shaft. Used in a ball screw comprising: a nut having a ball rolling groove on an inner peripheral surface; and a plurality of balls disposed in a ball raceway formed between both ball rolling grooves of the nut and the screw shaft, A ball circulating member having a scooping portion for scooping up a ball in one of the ball raceways from one side, and a ball circulation passage for returning the ball scooped up by the scooping portion from the other side into the ball raceway. In the range where the scooping portion is opposed to the ball rolling groove of the screw shaft, the distance in the deflection direction is larger than the boundary portion between the ball rolling groove and the escape groove of the screw shaft. Shape with other parts, narrower part It is characterized in that it is.
Here, the deflection direction is a direction in which the scooping portion deforms when the ball is scooped up by the scooping portion, and a direction along the radial direction of the screw shaft at the center in the width direction of the scooping portion. Say.
Further, the present invention is a ball screw, and is characterized by including the ball circulation member according to the present invention.

  According to the ball circulation member of the present invention, the scooping portion has a distance in the deflection direction with respect to the ball rolling groove of the screw shaft at a boundary portion between the ball rolling groove and the relief groove of the screw shaft. In comparison, since the other portion is formed with a narrower portion, according to the ball screw according to the present invention using this, for example, the boundary between the ball rolling groove and the escape groove of the screw shaft Even if the scooping part is pressed against the part, the scooping part does not contact at the boundary between the ball rolling groove and the escape groove of the screw shaft, and the other part contacts the ball rolling groove of the screw shaft. . Alternatively, other portions than the boundary portion between the ball rolling groove and the escape groove of the screw shaft make strong contact with the ball rolling groove of the screw shaft. Therefore, contact between the boundary between the ball rolling groove and the escape groove of the screw shaft and the back surface of the scooping portion can be prevented or the degree of the contact can be reduced.

Here, in the scooping-up portion, the scooping-up direction at the scooping point is a tangential direction of the ball pitch circle in the direction orthogonal to the screw shaft, and the lead of the ball pitch circle in the direction parallel to the screw shaft. It is preferable if it is formed along the angular direction.
With such a configuration, in particular, in order to smoothly guide the ball rolling on the spiral ball raceway into the ball circulation member, and to smoothly return the ball moving in the ball circulation member to the ball raceway, It is suitable for applying the ball circulating member according to the present invention to a ball screw of a type that picks up a ball in the tangential direction of the track and returns the ball into the ball track from the tangential direction of the ball track. And in this kind of ball screw, since the tip part of the scooping part becomes thin, the ball circulating member is particularly preferable for suppressing damage to the scooping part. Further, the thickness of the scooping portion (the distance from the tip portion of the scooping portion to the protruding portion formed on the opposite side, as shown by the symbol D in FIG. 6B described later) is The ball diameter used is 10% or more, more preferably 50% or more and 300% or less.

  Further, the scooping portion has a gap in the deflection direction in a range facing the ball rolling groove of the screw shaft, and the gap in the deflection direction allows a ball screw to which the clearance is applied to have an allowable rotational speed. It is preferable if the width is in contact with the ball rolling groove of the screw shaft when operated within the range. If the ball circulating member according to the present invention having such a configuration is applied to a ball screw, the scooping portion does not always come into contact with the ball rolling groove of the screw shaft, thereby suppressing wear of the scooping portion. it can. Then, assuming that the scooping portion and the ball rolling groove of the screw shaft come into contact in advance, the scooping portion is bent (elastically deformed) by the force applied thereto, and the scooping portion and the screw shaft are By intentionally contacting the ball rolling groove, the scooping portion can be supported (backed up) from behind by the ball rolling groove of the screw shaft.

  Further, it is preferable that the ball circulating member according to the present invention is used for the ball having a diameter of 5 mm or more. Such a configuration is particularly effective for use in a region where the mass of the ball is large. That is, when the ball has a diameter of 5 mm or more, the impact force applied to the scooping portion is particularly large, which is preferable in applying the ball circulation member according to the present invention.

  As described above, according to the present invention, even when the scooping portion of the ball circulation member comes into contact with the ball rolling groove of the screw shaft, it is possible to prevent or suppress the scooping of the scooping portion.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. In addition, about the part similar to the ball screw mentioned above, it attaches | subjects and demonstrates the same code | symbol also in description in the following embodiment.
FIG. 1 is an explanatory view of a side cap type ball screw according to the present invention, and FIG. 2 is a radial cross-sectional view in FIG. FIG. 3 is a view taken in the direction of the arrow E in FIG. 2 and shows the nut before the side cap is attached. FIG. 4 is a perspective view showing an image of a state in which the side cap cover is attached to the side cap.
As shown in FIGS. 1 and 2, the ball screw 10 includes a screw shaft 12 and a nut 14.

  The screw shaft 12 has a spiral ball rolling groove 11 on the outer peripheral surface. The nut 14 has a spiral ball rolling groove 13 corresponding to the ball rolling groove 11 of the screw shaft 12 on the inner peripheral surface. The nut 14 is fitted to the screw shaft 12, and the ball rolling groove 13 of the nut 14 and the ball rolling groove 11 of the screw shaft 12 face each other, and the ball raceway 8 is configured between the two. Has been. The ball raceway 8 is loaded with a plurality of balls 15 as rolling elements so as to roll. Here, in the ball screw 10 according to the present invention, it is preferable that the ball to be loaded is used for a ball having a diameter of 5 mm or more. The present embodiment is a large side cap ball screw, and the diameter of the ball is 19.05 mm.

Further, as shown in FIG. 3, the nut 14 has a side cap attachment surface 16 formed of a rectangular flat surface on the outer peripheral surface thereof. A pair of long holes 20 are formed in the side cap mounting surface 16. The long hole 20 is drilled in communication with the ball raceway 8 formed between the ball rolling grooves 11 and 13.
As shown in FIG. 4, a side cap 17 as a ball circulation member is attached to the side cap attachment surface 16. Here, the side cap 17 has a pair of leg portions 19, and the pair of leg portions 19 is perpendicular to the screw shaft 12 in the long hole 20 formed in the side cap mounting surface 16. It can be fitted from the direction with almost no gap (see FIG. 1). Then, as shown in FIG. 4, the side cap 17 is pressed toward the side cap mounting surface 16 by a lid-shaped side cap cover 26 that covers a portion other than the leg portion 19, and a nut is secured by a set screw 18. 14 is attached.

  Here, a ball scooping (returning) passage 21 is formed in the side cap 17 inside the leg portion 19 (see FIG. 2). The ball scooping (returning) passage 21 is formed by inclining the continuous direction of the passage with respect to the outer peripheral wall surface of the leg portion 19 and further inclining in the direction along the circulation passage direction of the ball. . The ball scooping (returning) passage 21 communicates with the ball feeding passage 22, and the ball feeding passage 22 and the pair of ball scooping (returning) passages 21 constitute a ball circulation passage 27.

  That is, as shown in FIG. 2, the side cap 17 has a ball circulation passage 27 having an integral structure along the continuous direction of the ball circulation passage 27 by a ball scooping (returning) passage 21 and a ball feed passage 22. The ball scooping (returning) passage 21 formed in the leg portion 19 is formed while the leg portion 19 can be easily fitted into the long hole 20 formed in the side cap mounting surface 16. The three-dimensional configuration is such that the traveling direction of the ball 15 can be raised in a direction substantially tangential to the screw shaft 12 and in a direction substantially coincident with the lead angle of both the ball rolling grooves 11 and 13. Therefore, the processing of the nut 14 is simple, and the design flexibility of the ball circulation passage 27 (that is, the ball scooping (returning) passage 21 and the ball feeding passage 22) can be improved.

The ball circulation passage 27 and the ball raceway 8 constitute an infinite circulation passage for the ball 15. Note that, for example, an output shaft of a motor (not shown) can be connected to one end of the screw shaft 12 via a coupling, whereby the nut 14 rotates the ball 15 by the rotation of the screw shaft 12. It is movable in the axial direction through movement.
Here, the above-described side cap 17 has a divided structure. FIG. 5 is a perspective view showing the side cap. FIG. 6 is an explanatory view showing one side cap constituting member obtained by dividing the side cap. FIG. 6A is a perspective view showing the whole, and FIG. The enlarged view of A part in a), the figure (c) is the expansion perspective view seen from the B direction in the figure (a), and the figure (d) is the magnification which shows the part which scoops up a ball with a screw axis. It is a perspective view. FIG. 7 is a view of the scooping portion 24 as seen from the direction of scooping up the ball (direction C in FIG. 6A). In the figure, only the outline is shown.

The side cap 17 is manufactured by resin molding. As shown in FIG. 5, for example, a combination of the side cap constituent members 23, which are a pair of ball circulation member constituent members formed by molding a resin material, face each other. Configured.
That is, as shown in FIG. 6, the side cap constituting member 23 is divided into two side caps 17 in a point-symmetric manner along the traveling direction of the ball 15 (the dividing line is indicated by PL in FIG. 5). A ball circulation passage 27 including a ball scooping (returning) passage 21 and a ball feeding passage 22 is formed inside thereof. Each side cap component member 23 has a scooping portion 24 at the tip of the ball scooping (returning) passage 21.

  As shown in FIG. 6, the scooping portion 24 has a screw shaft for smoothly scooping the ball 15 rolling in the ball raceway 8 from the ball raceway 8 to the ball scooping (returning) passage 21. It has a tongue-like shape that can be inserted into the 12 ball rolling grooves 11, and is formed to protrude from the ball scooping (returning) passage 21 toward the ball rolling groove 11. In the scooping portion 24, the scooping direction at the scooping point is a tangential direction of the ball pitch circle in the direction perpendicular to the screw shaft 12, and the lead of the ball pitch circle in the direction parallel to the screw shaft 12. It is formed along the angular direction.

Further, the scooping portion 24 extends with a gap in the deflection direction in the range facing the ball rolling groove 11, and the gap in the deflection direction is equal to the allowable rotational speed of the ball screw. When operated within the range, it is elastically deformed so as to be in contact with the ball rolling groove 11.
Therefore, when the scooping portion 24 and the ball rolling groove 11 are shown in a cross-section along a direction perpendicular to the scooping up direction of the ball 15 in an unloaded state, as shown in FIG. The back surface 24r is formed along the ball rolling groove 11 with a slight gap as a surface facing it. Here, in the scooping portion 24, the back surface 24 r has a distance in the facing direction in the range facing the ball rolling groove 11 of the screw shaft 12 and the ball rolling groove 11 of the screw shaft 12. Compared with the boundary portion 9b with the escape groove 9, the other portion is formed with a narrower portion.

  More specifically, as shown in FIG. 7, a curved recess 24 n is formed on the back surface 24 r of the scooping portion 24 at a position facing the escape groove 9. The recess 24n is provided along the scooping direction. The width dimension Wt of the recess 24n is wider than the width dimension W of the escape groove 9. Further, the back surface 24r of the scooping portion 24 at this time is in contact with the ball rolling groove 11 at the boundary portion 24t between the recess 24n and the back surface 24r in the range facing the ball rolling groove 11 of the screw shaft 12. The distance in the facing direction is narrower than the distance in the facing direction in other parts. The width dimension Wt of the recess 24n is suitably in the range of more than 1 and less than or equal to 2 times the width dimension W of the relief groove 9. Thereby, as shown in FIGS. 6B and 6C, the center of the tip portion 24s of the scooping portion 24 becomes a substantially U-shaped escape portion 24d, and both sides of the escape portion 24d are shown in FIG. As shown in b), it is formed as two corners 24p.

  The rear surface 24r of the scooping portion 24 is provided with a protruding portion 24u extending along the direction in which the concave portion 24n is extended on the side opposite to the tip portion 24s. The shape of the protruding portion 24u viewed from the back surface 24r side is substantially rectangular, and the width direction dimension is narrower than the width dimension Wt of the recess 24n. Here, the thickness of the scooping portion (as shown by the symbol D in FIG. 6B), the distance from the tip portion 24s of the scooping portion to the protrusion 24u formed on the opposite side thereof. Is 10% or more of the diameter of the ball used, more preferably 50% or more and 300% or less.

Next, functions and effects of the ball circulation member and the ball screw will be described.
As described above, according to the ball screw 10, the scooping portion 24 of the side cap 17 scoops up the ball 15 in the tangential direction at the scooping point on the ball rolling groove 11. Therefore, the ball 15 can be scooped up smoothly. Therefore, since the impact force when the ball 15 collides with the scooping portion or 24 other parts becomes weak, it is possible to realize high speed and low noise.

Incidentally, as described above with reference to FIGS. 14 to 17, when the ball 15 circulates in the side cap, a relatively large force F may be applied to the scooping portion temporarily. (See FIG. 14). In such a case, the scooping-up portion cannot support the applied force F only by the rigidity of the resin material, and there is a possibility that damage such as breakage may occur.
However, according to the ball screw 10, the scooping portion 24 of the side cap 17 has a gap in the deflection direction in the range facing the ball rolling groove 11, and the gap in the deflection direction is When the ball screw 10 is operated within the allowable rotational speed range, the ball screw 10 is in contact with the ball rolling groove 11 so that the ball rolling groove 11 of the screw shaft 12 causes the scooping portion 24 to move behind. Can be backed up from. Therefore, even when a large load is applied to the scooping portion 24, excessive deformation of the scooping portion 24 can be prevented or suppressed, and damage such as breakage of the scooping portion 24 can be prevented.

  Further, as described with reference to FIG. 15, the ball rolling groove 11 of the screw shaft 12 has a grinding clearance at the bottom portion of the ball rolling groove 11 in order to reduce grinding resistance when grinding. A relief groove 9 is provided. Therefore, as described with reference to FIG. 16, in the conventional scooping portion, when backed up by the ball rolling groove 11, the boundary portion between the ball rolling groove 11 and the relief groove 9 of the screw shaft 12. When the back surface of the scooping portion 240 is pressed against 9b, the back surface will be wrinkled.

  However, according to the ball screw 10, the scooping-up portion 24 of the side cap 17 has a distance in the deflection direction with respect to the ball rolling groove 11 of the screw shaft 12 so that the ball rolling groove 11 and the relief groove 9 are separated. Compared to the boundary portion 9b, the other portion, that is, the boundary portion 24t between the concave portion 24n and the back surface 24r is formed to have a narrower portion. Even if pressed, the scooping portion 24 does not make initial contact at the boundary portion 9b, and the boundary portion 24t between the recess 24n and the back surface 24r contacts the ball rolling groove 11 first. Therefore, the contact between the boundary portion 9b between the ball rolling groove 11 and the escape groove 9 of the screw shaft 12 and the back surface 24r of the scooping portion 24 can be prevented or the degree of the contact can be reduced. Here, regarding the wear due to the contact between the ball rolling groove 11 and the back surface 24r of the scooping portion 24, the surface of the ball screw is sufficiently smooth. Compared with the boundary portion 9b between the moving groove 11 and the escape groove 9, the degree of wear is very small. Furthermore, if the position of the ball rolling groove 11 in contact with the boundary portion 24t is a portion where the ball 15 rolls in a normal operation (for example, a portion that rolls with an operation at 10% of the dynamic rated load), Since the projections on the surface of the ball rolling groove 11 are crushed by the balls 15, wear is further reduced.

Therefore, according to this ball screw 10, it is possible to prevent or suppress the scooping of the scooping portion 24. Further, stress concentration caused by contact with the boundary portion 9b is also alleviated, so that breakage that occurs at the base point is prevented.
Furthermore, according to the ball screw 10, the concave portion 24n is provided, so that the center of the tip portion 24s of the scooping portion 24 becomes a substantially U-shaped escape portion 24d as shown in FIG. 6B. Both sides of the escape portion 24d are formed as two corner portions 24p. As a result, when the ball 15 is scooped up by the scooping portion 24, the ball 15 is scooped up by the two corner portions 24p, so that the posture of the ball during scooping is stabilized. Further, the two corner portions 24p of the scooping portion 24 are located on an extension line of the boundary portion 24t between the recess 24n and the back surface 24r. Therefore, when the ball rolling groove 11 and the back surface 24r of the scooping portion 24 come into contact with each other, each corner portion 24p is supported (backed up) from behind, so that the posture of the ball 15 during scooping is further stabilized. be able to.

  The side cap 17 assembled to the nut 14 is positioned with the scooping portion 24 based on the position of the screw shaft 12 with the ball rolling groove 11, so the positional relationship with the scooping portion 24 is the position described above. By accurately assembling, the degree of elastic deformation of the scooping portion 24 due to the contact between the ball rolling groove 11 and the back surface 24r of the scooping portion 24 can be reduced.

Next, an embodiment in which the present invention is applied to a ball screw and the wrinkles at the scooping portion are verified will be described. In addition, a present Example is an example which applied this invention with respect to the side cap type large ball screw like the said embodiment.
As the ball screw in this example, a ball screw having a nominal number “BS8025” (ball diameter: 19.05 mm) was used. As a testing machine, a ball screw durability life testing machine made by NSK was used. The test body is equipped with the conventional side cap described with reference to FIG. 13 and the like, and the side surface in which the shape of the recess 24n is formed on the back surface 24r of the scooping portion 24 according to the present invention by machining. Each equipped with a cap 17 was prepared.

  Then, each ball screw was applied to the above testing machine and a 100 km running test was performed at a DN value of 160,000 mm · r / min, and then the surface condition of each scooping portion was examined. The results are shown in FIG. 8 and FIG. FIG. 8 is a diagram of a state after the test at the scooping portion 24 according to the present invention, where FIG. 8 (a) is from the back side, and FIG. 8 (b) is opposite to the back side. It is the figure seen from the side. On the other hand, FIG. 18 is a diagram of a state after a test with a conventional side cap. FIG. 18 (a) is viewed from the back side, and FIG. 18 (b) is viewed from the side opposite to the back side. It is a figure.

As a result, in the conventional side cap, as can be seen from FIG. 18, linear wrinkles occurred due to the contact between the screw shaft 12 and the ball rolling groove 11 in the scooping portion. This wrinkle was generated at a position just in contact with the boundary portion 9b on the back surface of the scooping portion. Further, the occurrence of wrinkles due to contact at the boundary portion 9b occurs when the conventional ball circulating member is a ball screw using a ball having a relatively large diameter and when it is used at high speed. It was confirmed that it often occurred on the back of the raised portion. More specifically, wrinkles at the boundary portion 9b were particularly remarkable when the ball diameter was 5 mm or more. Moreover, it was remarkable when DN value (The outer diameter mm of a screw shaft x rotation speed min < ^-1 >) exceeded 100,000 times.

On the other hand, in the side cap according to the present invention, as can be seen from FIG. 8, no wrinkles due to contact of the screw shaft 12 with the ball rolling groove 11 were observed in the scooping portion. As described above, according to the ball screw 10 including the side cap 17 according to the present invention, it was confirmed that the scooping-up portion 24 can be prevented or suppressed.
Here, in the ball screw in the present embodiment, a ball having a diameter of 19.05 mm is used, and the side cap 17 has a shape corresponding thereto. That is, according to the present embodiment, the scooping portion 24 is wrinkled even when applied to a ball screw having a specification with a large impact force applied to the scooping portion, that is, when the ball diameter is 5 mm or more. It was confirmed that it can be prevented or suppressed.

As described above, according to the side cap 17 and the ball screw 10 including the side cap 17, even when the scooping portion 24 of the side cap 17 and the ball rolling groove 11 of the screw shaft 12 are in contact, the scooping portion It is possible to prevent or suppress wrinkling of 24.
The ball circulation member and the ball screw according to the present invention are not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the side cap 17 that is a ball circulation member is described as being formed from a resin. However, the present invention is not limited to this, and the ball circulation member may be made of metal such as a sintered alloy. Good. However, in the case of a ball circulating member, such as scooping up the ball in the tangential direction at the scooping part, the path through which the scooped ball circulates is somewhat complicated, so the processing cost is reduced and the strength in the structure In order to set a required portion to a desired thickness, it is preferable to mold the ball circulation member according to the present invention from a resin.

  Further, for example, in the above embodiment, the side cap 17 has been described as an example of scooping the ball in the tangential direction at the scooping portion, but the present invention is not limited to this, and the ball circulation that scoops the ball in directions other than the tangential direction The present invention can also be applied to members. However, the ball is picked up smoothly, the impact force when the ball collides with the scooping part and other parts is reduced, speeding up and noise reduction are achieved, and toward the ball rolling groove side of the screw shaft In order to suitably prevent or suppress the scooping of the scooping portion provided protruding in the shape of a tongue, the scooping direction at the scooping point of the ball circulation member according to the present invention is It is preferable to apply to a ball circulating member formed along the lead angle direction of the ball pitch circle in the direction perpendicular to the tangential direction of the ball pitch circle and parallel to the screw axis. Also, the ball circulation member that picks up the ball in the tangential direction is not limited to the side cap type, and can be applied to, for example, a ball circulation member with an end deflector type or an end cap type ball screw. Furthermore, in this case, if these ball circulation members are made of resin, it is more preferable in applying the present invention.

  Moreover, in the said embodiment, the side cap 17 has the recessed part 24n curved in the position facing the escape groove 9 in the back surface 24r of the scooping part 24, and this recessed part 24n is along said scooping direction. Since the recess 24n is formed, the center of the tip portion 24s of the scooping portion 24 becomes a substantially U-shaped relief portion 24d, and both sides of the relief portion 24d have two corner portions. Although the example formed as 24p has been described, the shape for avoiding interference with the boundary portion 9b between the ball rolling groove 11 and the escape groove 9 is not limited to this.

  For example, without forming the concave portion 24n provided along the scooping direction on the back surface 24r of the scooping portion 24, the substantially U-shape as described above is simply provided at the center of the tip portion 24s of the scooping portion 24. Only the relief portion 24d may be provided. Even with such a configuration, stress concentration caused by contact with the boundary portion 9b at the tip portion 24s having the thinnest wall thickness is alleviated, so that breakage occurring at that point can be prevented. In addition, if such a structure is employ | adopted, there also exists an advantage that the structure of the scooping part which concerns on this invention can be included with respect to the scooping part of the conventional side cap. However, in order to more preferably prevent or suppress the scooping up of the scooping portion 24, the shape for avoiding interference with the boundary portion 9b is scooped up like the recessed portion 24n illustrated above. It is desirable to provide along.

  Further, for example, in the above embodiment, the side cap 17 has a curved recess 24n formed in the back surface 24r of the scooping portion 24 at a position facing the escape groove 9, and the width dimension Wt is defined as the escape groove. 9 is wider than the width dimension W. Thereby, the scooping-up portion 24 has a gap in the deflection direction with respect to the ball rolling groove 11 of the screw shaft 12 as compared with the boundary portion 9b between the ball rolling groove 11 and the escape groove 9. In the example, the boundary portion 24t between the recess 24n and the back surface 24r is formed to have a narrower portion, but the shape for avoiding interference with the boundary portion 9b is limited to this. First, the scooping portion according to the present invention has a distance in the facing direction in the range facing the ball rolling groove 11 as compared to the boundary portion 9b between the ball rolling groove 11 and the escape groove 9. It is only necessary that the other part is formed to have a narrower part.

  That is, the scooping portion 24 of the side cap 17 and the ball rolling groove 11 of the screw shaft 12 are not limited to a non-contact state in the initial state, and can be applied even when they are in contact with each other. However, the scooping portion is not always in contact with the ball rolling groove of the screw shaft, so that the scuffing portion is prevented from being worn, and the scooping portion and the ball rolling groove of the screw shaft are in contact with each other. Assuming this in advance, the scooping part is elastically deformed by the force applied thereto, and the scooping part and the ball rolling groove of the screw shaft are intentionally brought into contact with each other by the ball rolling groove of the screw shaft. In the configuration in which the scooping portion is supported (backed up) from behind, the scooping portion has a gap in the deflection direction in the range facing the ball rolling groove of the screw shaft as in the above embodiment. The clearance in the deflection direction is preferably wide enough to be in contact with the ball rolling groove of the screw shaft when a ball screw to which the clearance is applied is operated within the allowable rotational speed range.

Furthermore, a specific modification is shown in FIGS.
In the example shown in FIG. 9, two recesses 24c are provided in place of the recess 24n. The concave portions 24 c are formed at positions facing the boundary portion 9 b between the ball rolling groove 11 and the escape groove 9 on the back surface 24 r of the scooping portion 24. The distance in the facing direction at this time is equal to the facing distance Y1 between the boundary portion 9b and the innermost portion of the recess 24c, and the ridge line portion and the ball rolling groove that are outside in the width direction of each recess 24c. 11 is narrow. Therefore, even with such a configuration, it is possible to prevent or suppress the scooping of the scooping portion 24.

  Further, in the example shown in FIG. 10, convex portions 24v are provided in two places instead of the concave portions 24n. The convex portion 24v is formed at each position on the outer side in the width direction with respect to the boundary portion 9b between the ball rolling groove 11 and the escape groove 9 on the back surface 24r of the scooping portion 24. It is in contact with the ball rolling groove 11 at the most tip portion. Therefore, since the distance in the facing direction at this time is in contact with the ball rolling groove 11 as compared with the facing distance Y3 that is a gap between the boundary portion 9b and the back surface 24r, After all, the facing distance is narrow. Therefore, even with such a configuration, it is possible to prevent or suppress the scooping of the scooping portion 24.

It is a figure explaining one Embodiment of the ball screw concerning the present invention. It is radial direction sectional drawing in FIG. FIG. 3 is a view taken in the direction of arrow E in FIG. 2, and shows the nut before the side cap is mounted. It is a perspective view which shows the image of the state which attaches a side cap cover to a side cap. It is a figure explaining the side cap which concerns on this invention. It is a figure explaining the side cap structural member which concerns on this invention. It is a figure explaining the side cap structural member which concerns on this invention, In the same figure, the scooping up part is shown with the figure seen from the direction which scoops up a ball | bowl. In the scooping part which concerns on this invention, it is a figure which shows the scooping part prevented from being wrinkled. It is a figure explaining the modification of the side cap which concerns on this invention. It is a figure explaining the modification of the side cap which concerns on this invention. It is a figure explaining the conventional ball screw, The figure has shown the principal part with the cross section in an axial direction. It is a figure explaining the conventional side cap type ball screw, The figure has shown the principal part in the cross section in an axial direction. It is a perspective view ((a) and (b)) explaining the conventional side cap (side cap structural member). It is a figure explaining the image of the state where comparatively big force was applied to the scooping part according to the behavior of a ball. In the figure, only one side of a part of a screw shaft and a split type side cap is shown in a perspective view. It shows. It is a figure explaining the screw axis | shaft which has a ball rolling groove in the outer peripheral surface and the escape groove is formed in the ball rolling groove. Note that the symbol L in FIG. It is a figure explaining the conventional scooping up part, In this figure, the scooping up part is shown in the cross section along the direction orthogonal to the direction which scoops up a ball | bowl. In the conventional scooping part, it is a perspective view explaining the image of the state where the scissors were attached to the scooping part. It is a figure which shows the scooping part with a wrinkle in the conventional scooping part.

Explanation of symbols

8 Ball track 9 Relief groove 10 Ball screw 11 Ball rolling groove 12 Screw shaft 13 Ball rolling groove 14 Nut 15 Ball 16 Side cap mounting surface (Ball circulating member mounting surface)
17 Side cap (ball circulation member)
18 Set screw 19 Leg 20 Long hole 21 Ball scooping (returning) passage 22 Ball feed passage 23 Side cap component (ball circulation member component)
24 Scooping part 26 Side cap cover 27 Ball circulation passage

Claims (5)

A screw shaft having a ball rolling groove on the outer circumferential surface, and a relief groove formed in the ball rolling groove, and a nut having a ball rolling groove on the inner circumferential surface facing the outer circumferential surface of the screw shaft; And a plurality of balls disposed in a ball raceway formed between both ball rolling grooves of the nut and the screw shaft, and scooping the ball in the ball raceway from one side. A ball circulation member having a scooping portion to be raised, and a ball circulation passage for returning the ball scooped by the scooping portion from the other side into the ball raceway,
In the range where the scooping portion is opposed to the ball rolling groove of the screw shaft, the distance in the deflection direction is different from that of the boundary portion between the ball rolling groove and the relief groove of the screw shaft. A ball circulation member characterized in that the portion is formed to have a narrower portion.   The scooping-up portion has a scooping-up direction at the scooping point that is a tangential direction of the ball pitch circle in a direction orthogonal to the screw axis, and in a lead angle direction of the ball pitch circle in a direction parallel to the screw axis. The ball circulation member according to claim 1, wherein the ball circulation member is formed along the axis.   The scooping portion has a gap in the deflection direction in a range facing the ball rolling groove of the screw shaft, and the gap in the deflection direction allows a ball screw to which the clearance is applied to be within a range of allowable rotation speed. The ball circulation member according to claim 1, wherein the ball circulation member has a size that contacts with a ball rolling groove of the screw shaft when operated by.   The ball circulating member according to any one of claims 1 to 3, wherein the ball is used for a ball having a diameter of 5 mm or more.   A ball screw comprising the ball circulation member according to claim 1.