JP2016118267A - Ball circulation tube and ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball circulation tube capable of easily attaching components externally fitted to a nut and the ball circulation tube, and provide a ball screw device.SOLUTION: In a ball circulation tube 4 that forms a path connecting two separated places on a rolling path and circulates a ball 6, outer end parts 4a, 4b, which form outer ends arranged at the most separated position in a radial direction from a center axial line of a screw shaft 2 when attached to a ball screw device 1, include an adjustment margin for adjusting a distance from the center axial line of the screw shaft 2 to the outer end.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ball screw device used as a mechanical element for converting rotational motion into linear motion, for example, a steering device, a device for moving heavy objects, a processing device, a precision positioning device, and the like.

  Conventionally, as in the invention described in Patent Document 1, there is a ball screw device that fixes a ball circulation tube to a nut by covering the nut and the ball circulation tube with a metal sleeve in a circumferential direction.

JP-A-10-141465

  However, in the conventional ball screw device, the ball circulation tube formed on the nut so that the inner peripheral surface of the sleeve, the rotor, and the like covering the ball circulation tube and the nut properly contacts the ball circulation tube and the nut. There is a problem that the depth of the notch for fitting the nut and the outer diameter of the nut must be adjusted, and the adjustment work takes time.

  In view of the above problems, an object of the present invention is to provide a ball circulation tube and a ball screw device that can be fitted with nuts and parts that are externally fitted to the ball circulation tube.

In order to solve the above problems, the present invention provides:
A screw shaft having a spiral first rolling groove formed on the outer periphery, and a cylindrical portion through which the screw shaft is passed, and an inner peripheral surface of the cylindrical portion corresponding to the first rolling groove. A ball screw device having a nut formed with two rolling grooves, and housing a plurality of balls in a rolling path formed by the first rolling groove and the second rolling groove;
A ball circulation tube that forms a path connecting two spaced apart locations of the rolling path and circulates the ball;
When attached to the ball screw device, an outer end portion forming an outer end disposed at a position farthest in the radial direction from the central axis of the screw shaft adjusts a distance from the central axis to the outer end. The ball circulation tube is provided with an adjustment margin for the above.

  Preferably, the outer end portion is a protrusion.

  Preferably, the outer end portion is a thick portion formed thicker than other portions.

In order to solve the above-mentioned problem, the present invention
A screw shaft having a spiral first rolling groove formed on the outer periphery;
A nut having a cylindrical portion through which the screw shaft is passed, and a second rolling groove corresponding to the first rolling groove formed on the inner circumferential surface of the cylindrical portion;
A plurality of balls accommodated in a rolling path formed by the first rolling groove and the second rolling groove;
Forming a path connecting two spaced locations of the rolling path, and having a ball circulation tube for circulating the ball,
The ball circulation tube is an adjustment for adjusting the distance from the central axis to the outer end, the outer end forming the outer end disposed at a position farthest from the central axis of the screw shaft in the radial direction Provided is a ball screw device including a margin.

  Preferably, the outer end portion is a protrusion.

  Preferably, the outer end portion is a thick portion formed thicker than other portions.

  Further, preferably, it further includes a fixing member for fixing the ball circulation tube to the nut.

Preferably, the fixing member includes a fixing portion that covers a part of the ball circulation tube from the outside in the radial direction, and an attachment portion that is formed integrally with the fixing portion and attached to the cylindrical portion. Have
The radially outer surface of the fixed portion forms a curved surface disposed on the same cylindrical surface as the outer peripheral surface of the cylindrical portion.

  ADVANTAGE OF THE INVENTION According to this invention, the ball | bowl circulation tube and ball screw apparatus which can attach easily the components externally fitted to a nut and a ball | bowl circulation tube can be provided.

It is a top view of the ball screw device concerning a 1st embodiment. It is a mimetic diagram showing the section of the ball screw device concerning a 1st embodiment. It is a schematic diagram which shows the cross section of the ball screw apparatus which concerns on 2nd Embodiment. It is a schematic diagram which shows the cross section of the ball screw apparatus which concerns on 3rd Embodiment. It is a top view of a ball screw device concerning a modification of a 1st embodiment. It is a schematic diagram which shows the cross section of the ball screw apparatus which concerns on the modification of 1st Embodiment.

(First embodiment)
Hereinafter, the ball screw device according to the first embodiment of the present application and the ball circulation tube attached to the ball screw device will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a plan view of a ball screw device 1 according to the first embodiment. A ball screw device 1 is attached to a screw shaft 2 having a spiral first rolling groove formed on the outer peripheral surface, a nut 3 fitted on the screw shaft 2, and a plurality of balls 6 (FIG. 2). 2), and a temporary fixing cap 5 as a fixing member for fixing the ball circulation tube 4 to the nut 3.

  The nut 3 has a cylindrical cylindrical portion 3a and a flange 3b that is formed integrally with the cylindrical portion 3a at one end of the cylindrical portion 3a and extends radially outward. A second rolling groove corresponding to the first rolling groove formed on the outer circumferential surface of the screw shaft 2 is formed on the inner circumferential surface of the nut 3. The first rolling groove and the second rolling groove form a rolling path on which the plurality of balls 6 roll.

  FIG. 2 is a schematic view showing a cross section of the ball screw device 1 according to the first embodiment. A state in which a metal sleeve 7 is fitted onto the nut 3 and the ball circulation tube 4 is shown. The sleeve 7 is not a part constituting the ball screw device 1 according to the first embodiment.

  A plurality of balls 6 are accommodated between the rolling paths, and the screw shaft 2 and the nut 3 rotate relative to each other about the central axis of the screw shaft 2, thereby extending the screw shaft 2. Move relative to.

  A cutout portion 3 c is formed in the cylindrical portion 3 a of the nut 3. Both ends of the notch 3c penetrate from the outer peripheral surface to the inner peripheral surface of the cylindrical portion 3a. A ball circulation tube 4 is inserted into the notch 3c.

  The ball circulation tube 4 has a U-shaped overall shape, and the inside is a cavity penetrating from one end to the other end. The ball circulation tube 4 is inserted into the notch 3c of the nut 3 from both ends. Both ends of the ball circulation tube 4 are opened in the rolling path. Thereby, when the ball 6 rolled in the rolling path by the relative rotation of the screw shaft 2 and the nut 3 reaches one end of the ball circulation tube 4, it is scooped up by the ball circulation tube 4. It enters the inside of the ball circulation tube 4 and is discharged from the other end. In this way, the ball 6 can be circulated infinitely in the rolling path and the ball circulation tube 4.

  In FIG. 2, the ball circulation tube 4 is fixed to the nut 3 by the sleeve 7, but is temporarily fixed to the nut 3 by the temporary fixing cap 5 before the sleeve 7 is attached. .

  The temporary fixing cap 5 includes a fixing portion 5a that covers the central portion of the ball circulation tube 4 from the outside in the radial direction of the nut 3, and mounting portions 5b that are integrally formed with the fixing portion 5a on both sides of the fixing portion 5a. Become. As shown in FIG. 2, the fixing portion 5 a of the temporary fixing cap 5 has a thickness that does not reach the inner peripheral surface of the sleeve 7. That is, the radially outer surface of the fixing portion 5a of the temporary fixing cap 5 is disposed at a position closer to the central axis in the radial direction than the outer peripheral surface of the cylindrical portion 3a.

  The temporarily fixing cap 5 can be easily attached to the nut 3 by engaging the attachment portion 5 b with the engaging portion formed on the nut 3. Thereby, before attaching the sleeve 7 to the nut 3 of the ball screw device 1, for example, during transportation, it is possible to easily prevent the ball circulation tube 4 and thus the plurality of balls 6 from falling off the nut 3. Further, since the temporary fixing cap 5 is disposed radially inside the inner peripheral surface of the sleeve 7, the sleeve 7 can be attached without removing the temporary fixing cap 5. It is possible to prevent the ball circulation tube 4 from falling off.

  Further, conventionally, a method of covering the ball circulation tube 4 and the nut 3 with a cylindrical member has been adopted as a temporary fixing of the ball circulation tube 4. However, the cylindrical member can rotate relative to the nut 3 and transmit torque. Therefore, it could not be used with a nut rotation type ball screw device. On the other hand, according to the first embodiment, since a rotor or the like can be attached to the nut 3 so as to be able to transmit torque, the ball screw device 1 can be used by rotating the nut.

  The ball circulation tube 4 has a pair of protrusions 4a, 4b arranged on the outer peripheral surfaces on both sides of the temporary fixing cap 5 so as to protrude outward in the radial direction of the screw shaft 2. Have. The protrusions 4 a and 4 b have a substantially hemispherical shape and protrude to a height that reaches the same cylindrical surface as the outer peripheral surface of the cylindrical portion 3 a of the nut 3. Therefore, the protrusions 4 a and 4 b come into contact with the inner peripheral surface of the sleeve 7 when the sleeve 7 is externally fitted to the nut 3.

  With such a configuration, by adjusting the protrusion height of the protrusions 4 a and 4 b, the tips of the protrusions 4 a and 4 b are brought into contact with the inner peripheral surface of the sleeve 7, and the ball circulation tube 4 is attached to the nut 3 by the sleeve 7. Can be easily fixed. That is, the protrusions 4 a and 4 b, which are outer end portions arranged at positions farthest from the central axis of the screw shaft 2, are provided with adjustment margins for fitting with the sleeve 7. Accordingly, in order to attach the sleeve 7, it is necessary to adjust the shape and dimensions such as the depth of the notch 3 c of the nut 3, the outer diameter of the cylindrical portion 3 a of the nut 3, and the shape of the inner peripheral surface of the sleeve 7. Disappear. Further, the ball circulation tube 4 configured as described above can correspond to nuts 3 having various outer diameters. As the adjustment of the protruding height of the protruding portions 4a and 4b, for example, the protruding portions 4a and 4b are set higher in advance, that is, the tips of the protruding portions 4a and 4b are positioned radially outward from the inner peripheral surface of the sleeve 7. There is a method of setting the height and grinding the protrusions 4a and 4b in accordance with the outer diameter size, notch depth, manufacturing error, etc. of the nut 3 to be attached.

(Second Embodiment)
Next, a ball screw device 1 according to a second embodiment of the present application will be described with reference to FIG. The ball screw device 1 according to the second embodiment has the same configuration as the ball screw device 1 according to the first embodiment except for the configuration of the temporary fixing cap. Therefore, in the description of the second embodiment, parts corresponding to those of the ball screw device 1 according to the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description overlapping with the first embodiment is omitted. The configuration of the temporary fixing cap 5 and the effects specific to the second embodiment will be described.

  FIG. 3 is a schematic view showing a cross section of the ball screw device 1 according to the second embodiment. As shown in FIG. 3, in the temporary fixing cap 5, the fixing portion 5 a that is in contact with the ball circulation tube 4 is in contact with the inner peripheral surface of the sleeve 7. That is, the surface of the fixing portion 5 a radially outside the temporary fixing cap 5 has the same radius of curvature as the outer peripheral surface of the cylindrical portion 3 a of the nut 3 and the same column as the outer peripheral surface of the cylindrical portion 3 a of the nut 3. A curved surface arranged on the surface is formed.

  According to the second embodiment, in addition to the effects of the first embodiment, the two projecting portions 4a and 4b and the fixing portion 5a of the temporary fixing cap 5 are in contact with the inner peripheral surface of the sleeve 7. Therefore, the ball circulation tube 4 can be fixed more firmly.

(Third embodiment)
Next, a ball screw device 1 according to a third embodiment of the present application will be described with reference to FIG. The ball screw device 1 according to the third embodiment has the same configuration as the ball screw device 1 according to the second embodiment except for the configuration of the ball circulation tube 4. Therefore, in the description of the third embodiment, parts corresponding to those of the ball screw device 1 according to the second embodiment are denoted by the same reference numerals as those of the second embodiment, and description overlapping with the second embodiment is omitted. Omitted, the configuration of the ball circulation tube 4 and the effects specific to the third embodiment will be described.

  FIG. 4 is a schematic view showing a cross section of the ball screw device 1 according to the third embodiment. As shown in FIG. 4, the ball circulation tube 4 has a portion disposed on the sleeve 7 side, that is, a portion disposed on the radially outer side of the screw shaft 2, thicker than other portions except for the central portion. Is formed. In other words, the thickness of the ball circulation tube 4 disposed outside in the radial direction of the screw shaft 2 is formed so that the thickness gradually increases from the center of the ball circulation tube 4 toward both ends. It has the flesh portions 4c and 4d, and both end portions are formed so that the wall thickness gradually decreases toward the end face side.

  In the third embodiment, the thick portions 4c and 4d serve as adjustment margins, and the same effect as in the second embodiment can be obtained.

  In the above, specific embodiments have been described to assist the understanding of the present invention, but the present invention is not limited to these embodiments, and various modifications and improvements can be made.

  For example, the shape of the protrusions 4a and 4b is not limited to that of the above embodiment, and various shapes that exhibit a function as an adjustment margin can be employed. For example, a conical shape or a semi-cylindrical shape may be employed.

  Moreover, in the said embodiment, in order to temporarily fix the ball | bowl lubrication tube 4 to the nut 3, the temporary fixing cap 5 was employ | adopted, However, Temporary fixing means is not restricted to this. In particular, in the first embodiment, a configuration in which the temporary fixing cap 5 does not contact the sleeve 7 is employed, and therefore various temporary fixing means other than the temporary fixing cap 5 can be used.

  As the temporary fixing cap 5, in addition to the embodiment described above, as shown in FIGS. 5 and 6, as shown in FIGS. 5 and 6, a temporary fixing cap 5 whose circular shape is circular and whose circumferential portion is coupled to the nut 3 is used. You can also. According to such a temporary fixing cap 5, it is possible to resist the force in which the ball circulation tube 4 tends to come off from the nut 3 with a good balance in the circumferential direction.

  As described above, according to the present invention, it is possible to provide a ball circulation tube and a ball screw device capable of easily attaching a part fitted on the nut and the ball circulation tube.

DESCRIPTION OF SYMBOLS 1 Ball screw apparatus 2 Screw shaft 3 Nut 3a Cylindrical part 3b Flange 3c Notch part 4 Ball circulation tube 4a, 4b Protrusion part 4c, 4d Thick part 5 Temporary fixing cap 5a Fixing part 5b Mounting part 6 Ball 7 Sleeve

Claims (8)

A screw shaft having a spiral first rolling groove formed on the outer periphery, and a cylindrical portion through which the screw shaft is passed, and an inner peripheral surface of the cylindrical portion corresponding to the first rolling groove. A ball screw device having a nut formed with two rolling grooves, and housing a plurality of balls in a rolling path formed by the first rolling groove and the second rolling groove;
A ball circulation tube that forms a path connecting two spaced apart locations of the rolling path and circulates the ball;
When attached to the ball screw device, an outer end portion forming an outer end disposed at a position farthest in the radial direction from the central axis of the screw shaft adjusts a distance from the central axis to the outer end. A ball circulation tube comprising an adjustment margin for the purpose.   The ball circulation tube according to claim 1, wherein the outer end portion is a protrusion.   The ball circulation tube according to claim 1, wherein the outer end portion is a thick portion formed thicker than other portions. A screw shaft having a spiral first rolling groove formed on the outer periphery;
A nut having a cylindrical portion through which the screw shaft is passed, and a second rolling groove corresponding to the first rolling groove formed on the inner circumferential surface of the cylindrical portion;
A plurality of balls accommodated in a rolling path formed by the first rolling groove and the second rolling groove;
Forming a path connecting two spaced locations of the rolling path, and having a ball circulation tube for circulating the ball,
The ball circulation tube is an adjustment for adjusting the distance from the central axis to the outer end, the outer end forming the outer end disposed at a position farthest from the central axis of the screw shaft in the radial direction A ball screw device comprising a margin.   The ball screw device according to claim 4, wherein the outer end portion is a protruding portion.   5. The ball screw device according to claim 4, wherein the outer end portion is a thick portion formed thicker than other portions.   The ball screw device according to any one of claims 4 to 6, further comprising a fixing member for fixing the ball circulation tube to the nut. The fixing member includes a fixing portion that covers a part of the ball circulation tube from the outside in the radial direction, and an attachment portion that is formed integrally with the fixing portion and attached to the cylindrical portion,
The surface on the radially outer side of the fixed portion forms a curved surface disposed on the same cylindrical surface as the outer peripheral surface of the cylindrical portion. The ball screw device described.

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