JP2008008454A - Ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw capable of dispensing with a tube presser and capable of dispensing with screw fastening work in the attachment of a ball circulating tube. <P>SOLUTION: This ball screw 1 has an endless circulating passage wherein a large number of balls 5 are circulated, and the ball circulating tube 8 constituting the endless circulating passage. A nut 6 has an attachment hole 7 so that the ball circulating tube 8 can be fitted into it. Further, the attachment hall 7 is provided with a coming-off prevention means 50 for preventing the movement of the ball circulating tube 8 to a coming-off direction, and the coming-off prevention means 50 has a fit-in hole 10 formed at the inner wall surface of the attachment hole 7 and opened to the ball circulating tube 8 side, and a ball (abutting member) 20 fitted in the fit-in hole 10 and abutting thereon so as to impart pressing force to the ball circulating tube 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ball screw having a ball circulation member, and more particularly to a structure for fixing a ball circulation member to a mounting hole of a nut.

As a ball screw having a ball circulation member, for example, an external circulation system in which a ball is circulated through a ball circulation tube as a ball circulation member is known.
As shown in FIG. 11, the ball circulation tube 800 is exposed and arranged on the outer surface of a nut 600 screwed to the screw shaft 300 via a large number of balls 500, and the ball 500 is placed outside the nut 600. It is a structure that guides and circulates.

In this type of ball screw, a tube retainer 150 is usually used to fix the ball circulation tube 800 to the outer surface of the nut 600. A ball circulation tube 800 and a mounting surface 900 for the tube retainer 150 are formed on the outer surface of the nut 600 by milling. The mounting surface 900 has a mounting hole 700 for inserting an end of the ball circulation tube 800, and A screw hole 110 for attaching the tube presser 150 is tapped.
JP 2002-89650 A

  However, in the above conventional ball screw, in order to fix the ball circulation tube 800, the tube presser 150 is necessary, and the nut 600 needs to be tapped with the screw hole 110. Further, when assembling the ball circulation tube 800, as shown in FIG. 11, it is necessary to pass the mounting screw 120 through the screw hole 100 of the tube presser 150 and tighten it into the screw hole 110. There is a problem that it takes. Further, in the screw tightening operation, the final tightening is usually performed after the temporary tightening, but the final tightening may be insufficient.

For such a problem, for example, in the technique described in Patent Document 1, the tube presser and the ball circulation tube are integrally formed. As a result, although the number of parts is reduced and the assembly is rationalized, the tightening operation with screws is necessary as described above, which is still insufficient.
Therefore, the present invention has been made paying attention to such problems, and it is an object of the present invention to provide a ball screw that does not require a tube presser and does not require a screw tightening operation when mounting a ball circulation member. It is said.

  In order to solve the above problems, the present invention provides a screw shaft having a spiral ball rolling groove on the outer peripheral surface, a nut having a load ball rolling groove facing the ball rolling groove on the inner peripheral surface, A ball circulation member comprising a plurality of balls rolling on a ball raceway formed between the ball rolling groove and a load ball rolling groove, and an infinite circulation path through which the ball circulates. And a mounting hole provided in the nut so that the ball circulating member can be fitted therein, the mounting hole having a retaining means for preventing the ball circulating member from moving in the pulling direction. The retaining means includes an insertion hole formed on an inner wall surface of the mounting hole and opening toward the ball circulation member, and a pressing force applied to the ball circulation member after being inserted into the insertion hole. To abut to give It is characterized by being configured to include a member.

According to the present invention, the mounting hole of the ball circulation member is provided with the retaining means for preventing the movement of the ball circulation member in the removal direction, so that the tube presser is not required when the ball circulation member is attached. be able to.
In the retaining means, an insertion hole that opens toward the ball circulation member is formed in the inner wall surface of the mounting hole of the ball circulation member, and a pressing force is applied to the ball circulation member in the insertion hole. Since the abutting member that abuts so as to be applied is inserted, the movement in the removal direction can be prevented only by inserting the ball circulation member into the mounting hole. Therefore, when attaching the ball circulation member, a screw tightening operation can be made unnecessary.

  According to the present invention, it is possible to provide a ball screw that does not require a tube presser and does not require a screw tightening operation when the ball circulation member is attached.

Embodiments of the present invention will be described below with reference to the drawings as appropriate.
FIG. 1 is a cross-sectional view of an essential part for explaining a first embodiment of a ball screw according to the present invention, and FIG. 2 is a plan view thereof.
As shown in FIGS. 1 and 2, the ball screw 1 includes a screw shaft 3 having a spiral ball rolling groove 2 on the outer peripheral surface and extending in the axial direction. A nut 6 having a spiral load ball rolling groove 4 corresponding to the ball rolling groove 2 on the inner peripheral surface is loosely fitted on the screw shaft 3. The load ball rolling groove 4 of the nut 6 and the ball rolling groove 2 of the screw shaft 3 are opposed to each other to form a spiral ball raceway between them, and a rolling element is formed on the ball raceway. Are loaded so that they can roll. 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).

  When the nut 6 (or screw shaft 3) moves in the axial direction, the ball 5 moves while rolling on the ball raceway, but the nut 6 (or screw shaft 3) is continuously moved. In order to go, it is necessary to circulate the ball 5 infinitely. Therefore, a part of the mounting surface 9 that is flattened on the outer surface of the nut 6 is machined with a milling cutter or the like, and a set of two mounting holes 7 that communicate with the ball raceway on the mounting surface 9 attaches the screw shaft 3. It is formed to straddle. Then, by fitting both ends of a substantially U-shaped ball circulation tube 8 serving as a ball circulation member into the set of mounting holes 7, the ball 5 is moved from one end of the ball raceway by the ball circulation tube 8. The endless circulation path of the ball 5 is formed by returning to the other end of the scooping ball raceway.

Here, in the ball screw 1, the mounting hole 7 is formed with a retaining means 50 that prevents the ball circulation tube 8 from moving in the direction of withdrawal. Hereinafter, the retaining means 50 will be described in detail.
As shown in FIGS. 1 and 2, the retaining means 50 is provided for each set of two mounting holes 7. In addition, since the structure of the retaining means 50 for each attachment hole 7 is the same, in the following description, only one location will be described.
The retaining means 50 includes a loading hole 10, a sphere 20, a cylindrical coil spring 30, and a plug 40.
Specifically, the insertion hole 10 is formed in the thick part of the nut 6 as a circular through hole along the axial direction of the screw shaft 3. The axis AL of the through hole extends toward the center of the ball circulation tube 8 whose cross section is annular, and opens toward the ball circulation tube 8 on the inner wall surface of the mounting hole 7.

The plug 40 is a short cylindrical member having an outer diameter that can be fitted into the insertion hole 10. The plug 40 is fixed to the end of the charging hole 10 opposite to the ball circulation tube 8 side by an adhesive. As a result, the insertion hole 10 is a bottomed hole having the plug 40 as a bottom and opening toward the ball circulation tube 8 side.
The sphere 20 is a contact member that is disposed on the ball circulation tube 8 side and contacts the ball circulation tube 8, and is a steel sphere having an outer diameter that can be fitted in the insertion hole 10. The outer diameter is slightly smaller than the inner diameter of the charging hole 10. Thereby, the sphere 20 can move while sliding in the axial direction of the insertion hole 10.

The cylindrical coil spring 30 is an elastic member interposed between the sphere 20 and the plug 40 and applies a pressing force due to the elastic deformation to the ball circulation tube 8 through the sphere 20. . Thereby, the sphere 20 can protrude from the inner wall surface of the mounting hole 7 to the ball circulation member side 8 while being pressed by the cylindrical coil spring 30. The protruding amount of the sphere 20 is set so that the sphere 20 does not fall into the mounting hole 7.
Then, as shown in FIG. 3, the spherical surface of the ball circulation tube 8 is fitted to the spherical surface at a position facing the ball 20 projecting to the ball circulation member side 8 when both ends thereof are fitted into the mounting holes 7. A matching recess 60 is formed. In this example, a concave spherical surface formed so as to follow the curved surface of the sphere 20 is formed as the concave portion 60.

Next, the action and effect of this ball screw will be described.
As described above, the ball screw 1 is configured to include the retaining means 50 for preventing the ball circulation tube 8 from moving in the removal direction in the mounting hole 7 of the ball circulation tube 8. At the time of mounting, it is possible to prevent the movement in the removal direction only by inserting the ball circulation tube 8 into the mounting hole 7. Accordingly, it is possible to eliminate the need for the tube presser exemplified by the conventional ball screw.

  The retaining means 50 has an insertion hole 10 that is open toward the ball circulation tube 8 on the inner wall surface of the mounting hole 7 of the ball circulation tube 8. Since the ball 20 that comes into contact with the tube 8 so as to apply a pressing force is inserted, when the ball circulation tube 8 is mounted, the screw tightening operation exemplified in the conventional ball screw is not required. it can.

Furthermore, according to the ball screw 1, the ball 20 protrudes from the inner wall surface of the mounting hole 7 toward the ball circulation tube 8, and the ball circulation tube 8 is formed with a recess 60 that fits with the protruding ball 20. Therefore, the movement of the ball circulation tube 8 in the removal direction can be more preferably prevented by fitting the two together.
Moreover, according to this ball screw 1, since the bottom part of the insertion hole 10 is formed by fixing the plug 40 with respect to a through-hole, it is easy to comprise as a bottomed hole which has a bottom part. is there.

Next, a second embodiment of the ball screw according to the present invention will be described. The second embodiment is the same as the first embodiment except that the configuration described below is different from the first embodiment except for the other configurations. The same reference numerals are given to the configurations, and the description thereof is omitted as appropriate.
As shown in FIG. 4, the second embodiment includes a ball return passage 79 penetrating along the axial direction of the nut 76, and a ball circulation passage 78a that connects the ball return passage 79 and the ball raceway. This is an example of a ball screw 71 provided with a circulating top 78 having a ball circulating member therein. In the second embodiment, the insertion hole 11 of the retaining means 51 is different from the first embodiment.
In this ball screw 71, the insertion hole 11 is formed as a bottomed hole having a bottom portion integrally, and as shown in FIG. The axis CL and the axis AL of the charging hole 11 are on the same axis.

  According to the ball screw 71 in the second embodiment, since the charging hole 11 is processed using the processing step of the ball return passage 79, the charging hole 11 can be processed simultaneously in one step. it can. In addition, since the bottomed hole having the bottom portion is formed without providing the bottom portion with the above-described plug 40 or the like, the number of parts is reduced compared to the first embodiment, and the retaining means 51 is made easier. Can be configured. Therefore, according to the ball screw 71 in the second embodiment, the processing cost and the assembly man-hour of at least one retaining means 51 can be reduced as compared with the first embodiment. The other actions and effects of the retaining means 51 are the same as in the first embodiment.

  Here, the circulation tops 78 illustrated in the second embodiment can be suitably configured by using the pair of the tops 78 as described above. Further, in each of the above embodiments, the retaining means has the same structure for each set of two mounting holes, and one of the positions has been described. However, the structure of the retaining means for each mounting hole may be different from each other. Good. Therefore, an example in which an endless circulation path is configured using a pair of circulation tops 78 and the configuration of the retaining means for each mounting hole is different from each other will be described as a third embodiment. In addition, about the structure similar to said each embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted suitably.

As shown in FIG. 5, the third embodiment has a pair of circulation tops 78 that are mounted at a predetermined distance in the axial direction of the nut 76. The pair of circulation tops 78 are mounted at positions twisted at a predetermined angle (for example, 90 °) in the circumferential direction, and the ball return passage 79 and the ball raceway can communicate with each other to form an infinite circulation path. Yes.
Here, in the ball screw 71 in the third embodiment, the charging hole 11 for fixing one circulation top 78 (left side in the figure) and the other circulation top 78 (right side in the figure). Both of the insertion holes 12 for fixing the ball are formed by utilizing the processing step of the ball return passage 79. That is, as shown in the figure, the axis CL of the ball return passage 79, the axis AL of the insertion hole 11, and the axis BL of the insertion hole 12 are all formed on the same axis.

  The pair of circulating tops 78 employs different retaining means for each mounting hole. That is, with respect to one circulating top 78, the retaining means 51 is configured by interposing the cylindrical coil spring 30 between the bottom of the insertion hole 11 formed as a bottomed hole and the ball 20. The retaining means 51 prevents the circulating top 78 from moving in the direction of withdrawal.

  For the other circulating top 78, the inner wall of the insertion hole 12 formed as a through hole is tapped, and the ball 20, cylindrical coil spring 30 and set screw 41 are inserted into the insertion hole 12. The retaining means 54 is configured by inserting in this order. As a result, by tightening the set screw 41, the circulating top 78 is prevented from moving in the removal direction.

  According to the ball screw 71 of the third embodiment, the charging hole 11 and the charging hole 12 use the processing step of the ball return passage 79 as compared with the case where a plurality of retaining means are formed individually. Thus, since a plurality of retaining means 51 and retaining means 54 can be formed simultaneously in one step, the retaining means 51 and retaining means 54 can be formed more easily. In addition, the processing cost and the number of assembly steps can be reduced. Further, with respect to the retaining means 54, the force for preventing the circulation top 78 from moving in the direction of withdrawal can be adjusted by the tightening amount of the set screw 41.

As described above, according to the ball screw of each of the above embodiments, it is possible to provide a ball screw that does not require a tube presser and does not require a screw tightening operation when the ball circulation member is attached.
In addition, the ball screw which concerns on this invention is not limited to said each embodiment, A various deformation | transformation is possible unless it deviates from the meaning of this invention.
For example, in the first embodiment, the bottom portion of the insertion hole 10 is formed with the plug 40 and the cylindrical coil spring 30 is interposed between the formed bottom portion and the ball 20. For example, as illustrated in FIG. 6, the cylindrical coil spring 30 may not be interposed. In this case, since the pressing force is applied to the ball circulation tube 8 by the elastic deformation of the ball 20 itself as the contact member, the configuration of the retaining means can be simplified.

Further, the bottom portion of the insertion hole 10 may be replaced with the plug 40, and the inner wall of the insertion hole 12 may be tapped and the bottom portion may be configured with the set screw 41 as in the third embodiment. In this case, the retaining means 52 can adjust the force that prevents the ball circulation tube 8 from moving in the withdrawal direction by the tightening amount of the set screw 41, as in the third embodiment.
Further, in each of the above embodiments, the example in which the contact member is configured as a sphere has been described. However, the present invention is not limited to this. For example, as illustrated in FIG. Also good. Further, as shown in the figure, the pin 21 is a stepped pin having a diameter 21b on the ball circulation tube 8 side and a larger diameter 21a on the opposite side, and the insertion hole 13 has a step difference. You may comprise the stepped hole corresponding to each diameter which it has. With such a configuration, it is possible to suitably prevent the pin 21 from dropping to the ball circulation tube 8 side.

  Further, in each of the above embodiments, each ball circulation member has been described as having an indentation 60 that fits into a contact member protruding toward the ball circulation member. However, for example, FIGS. As shown in FIG. 9, a cylindrical depression (see FIG. 8) or a truncated cone depression (see FIG. 9) may be used. Further, as shown in FIG. 10, the concave portion has various shapes such as small projections 60 a arranged at equal intervals in the circumferential direction (four locations in the example of the same figure) in the concave spherical recess. It can be.

  Furthermore, in each of the above-described embodiments and modifications, the insertion hole is formed as a bottomed hole having a bottom portion as the retaining means 50, 51, 52, 53, 54, etc. An example provided with an abutting member that is inserted and abuts so as to apply a pressing force to the ball circulation member, or is further interposed between the abutting member and the bottom of the insertion hole. However, the present invention is not limited to this. For example, the insertion hole is a through-hole whose inner wall is tapped, and the inside of the insertion hole is a contact member. A set screw having a gap in the gap, an elastic member provided in the gap of the set screw, and a sphere or the like provided in the gap and pressed toward the outside of the set screw by being pressed by the elastic member. With a so-called ball plunger. Stop can be a means missing Te.

It is principal part sectional drawing explaining 1st embodiment of the ball screw which concerns on this invention. It is a top view of the ball screw of FIG. It is a figure explaining the principal part of a ball | bowl circulation member, The figure (a) is a left view of the figure (b), The figure (b) shows the principal part of the ball | bowl circulation member in the ball screw of FIG. It is explanatory drawing expanded and shown. It is principal part sectional drawing explaining 2nd embodiment of the ball screw which concerns on this invention. It is a figure explaining 3rd embodiment of the ball screw concerning the present invention. It is a figure explaining the modification of the ball screw concerning the present invention. It is a figure explaining the modification of the ball screw concerning the present invention. It is a figure explaining the modification of the ball screw which concerns on this invention, and respond | corresponds to the said FIG. It is a figure explaining the modification of the ball screw which concerns on this invention, and respond | corresponds to the said FIG. It is a figure explaining the modification of the ball screw which concerns on this invention, and respond | corresponds to the said FIG. It is a perspective view for demonstrating an example of the conventional ball screw.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,71 Ball screw 2 Ball rolling groove 3 Screw shaft 4 Load ball rolling groove 5 Ball 6, 76 Nut 7 Mounting hole 7a Inner wall surface (of mounting hole) 8 Ball circulation tube (ball circulation member)
9 Mounting surface 10, 11, 12, 13 Insertion hole 20 Ball (contact member)
21 pin (contact member)
30 Cylindrical coil spring (elastic member)
40 Embedding 41 Set screw 50, 51, 52, 53, 54 Retaining means 60 Recessed portion 78 Circulating top (ball circulating member)
79 Ball return passage

Claims (9)

A screw shaft having a spiral ball rolling groove on the outer peripheral surface, a nut having a load ball rolling groove facing the ball rolling groove on the inner peripheral surface, the ball rolling groove and the load ball rolling groove, A plurality of balls that roll on a ball raceway constituted by the ball, a ball circulation member that forms an infinite circulation path through which the balls circulate, and the ball raceway, and the nut that can be fitted into the ball circulation member A ball screw provided with a mounting hole provided in
The mounting hole has a retaining means for preventing movement of the ball circulation member in the withdrawal direction,
The retaining means is formed on the inner wall surface of the mounting hole and opens toward the ball circulation member, and is inserted into the insertion hole to apply a pressing force to the ball circulation member. A ball screw comprising: an abutting member that abuts so as to make contact. The charging hole is a bottomed hole having a bottom,
The retaining means further comprises an elastic member interposed between the contact member and the bottom of the insertion hole,
The ball screw according to claim 1, wherein the elastic member is configured to apply a pressing force due to elastic deformation to the ball circulation member via the contact member.   The ball screw according to claim 2, wherein the elastic member is a cylindrical coil spring.   4. The ball screw according to claim 2, wherein the bottom portion of the insertion hole is formed by fixing a plug or a set screw to the through hole. The contact member projects from the inner wall surface of the mounting hole to the ball circulation member side,
The ball screw according to any one of claims 1 to 4, wherein the ball circulation member has a recess that fits into the protruding contact member.   The ball screw according to claim 1, wherein the contact member is a pin or a sphere.   The ball screw according to claim 1, wherein the contact member is a ball plunger.   8. The ball circulation member according to claim 1, wherein the ball circulation member is a ball circulation tube that scoops up the ball from one end of the ball raceway and returns it to the other end of the ball raceway. The ball screw described.   8. The ball circulation member includes a circulation passage having a ball circulation passage that communicates the ball return passage penetrating in the axial direction of the nut and the ball raceway. 9. Ball screw as described in.

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