JP2019203590A - Manufacturing method of ball screw nut, and ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball screw nut manufacturing method and a ball screw capable of suppressing vibration and noise generated when a ball passes through a boundary between a nut and a circulating top. A nut (20) of a ball screw (1) has a through hole (23) and a counterbore hole (24) penetrating in a radial direction at a position where a ball return passage (42) of the nut (20) is provided, and is positioned on an inner peripheral surface of the nut (20). The jig 50 is arranged, the circulating top 40 is brought into contact with the positioning jig 50, the circulating top 40 is positioned with respect to the nut 20, and an adhesive or a curable resin 61 is poured into the counterbore hole 24 to be cured. After that, the positioning jig 50 is manufactured by removing it from the nut 20. [Selection diagram] Figure 2

Description

  The present invention relates to a ball screw nut manufacturing method and a ball screw.

  A ball screw is a device that converts rotational motion into linear motion by circulating a plurality of balls in an infinite circulation path formed inside, and is widely used in machine tools, injection molding machines, semiconductor manufacturing equipment, etc. ing. Examples of the ball circulation method of the ball screw include a top type, an end cap type, and an end deflector type.

  In the top-type ball screw, the ball circulates over the outer diameter of the screw shaft. Ball screw nuts are generally manufactured using metal, resin, etc., and a ball having a ball return passage is assembled to the nut and fixed with an adhesive to circulate the ball. The outer diameter of the nut can be made compact.

  On the other hand, in the case of the top-type ball screw, there may be a large step at the boundary between the top ball return passage and the ball groove of the nut. When the ball passes through the step, vibration occurs or torque is locally There are concerns about problems such as rising. Moreover, since the top is fixed with an adhesive or the like, there is a problem that it is difficult to adjust the step or to reassemble the top.

  In the piece type ball screw described in Patent Document 1, shock absorbing members made of separate elastic members are attached to both ends of a piece member to be joined to the screw groove of the nut, and the screw groove of the nut and the ball circulation groove of the piece member The noise and vibration generated by the ball passing through the step of the joint are reduced.

JP 2004-138179 A

  The ball screw described in Patent Document 1 attempts to reduce adverse effects due to a step by inserting a buffer member between the ball circulation groove of the piece member and the ball groove of the nut. In addition, the step between the ball circulation groove of the piece member and the ball groove of the nut cannot be basically eliminated. Moreover, a space for incorporating the buffer member is required, and the nut outer diameter may be increased, so there is room for improvement.

  The present invention has been made in view of the above-described problems, and an object thereof is a ball screw capable of suppressing vibration and noise generated when the ball passes through a boundary portion between a nut and a top. It is in providing the manufacturing method of a nut and a ball screw.

The above object of the present invention can be achieved by the following constitution.
(1) A method for producing a nut for a ball screw, wherein a circulating top having a ball return passage connected to the screw groove is installed on a nut having a helical screw groove formed on an inner peripheral surface,
Preparing the nut having a through-hole formed in a radial direction at a position where the ball return passage is provided and a counterbore hole formed on the outer diameter side of the through-hole;
Placing a positioning jig on the inner peripheral surface of the nut where the through hole opens;
Contacting the circulating top with the positioning jig and positioning the circulating top inserted into the through hole with respect to the nut;
A step of pouring an adhesive or a curable resin into the counterbored holes and curing, and fixing the circulating top to the nut;
Removing the positioning jig from the nut;
A method for producing a ball screw nut, comprising:
(2) The positioning jig is arranged on an inner peripheral surface of the nut by fitting a screw groove fitting portion in which the shape of the screw groove of the nut is copied into the screw groove. The manufacturing method of the nut for ball screws as described in (1).
(3) The circulating top is fitted with a ball return passage fitting portion formed on the positioning jig, the shape of the ball return passage being copied. The ball screw nut manufacturing method according to (1) or (2), wherein the ball screw nut is positioned.
(4) Any one of (1) to (3), wherein the circulating top has a concave groove on an outer surface, and the concave groove is filled with the adhesive or a curable resin. The manufacturing method of the nut for ball screws as described in 2 ..
(5) Any of (1) to (4), wherein the counterbore has a fixing groove on an inner side surface, and the fixing groove is filled with the adhesive or a curable resin. A method for producing a nut for a ball screw according to claim 1.
(6) The method for producing a nut for a ball screw according to any one of (1) to (5), wherein the curable resin is an epoxy resin or a two-component epoxy resin.
(7) a screw shaft having a helical thread groove formed on the outer peripheral surface;
A nut disposed around the screw shaft and having a helical thread groove formed on the inner peripheral surface;
A plurality of balls accommodated in a rolling path formed by opposing screw grooves;
A circulation top attached to the nut and having a ball return passage for circulation from one end to the other end of the rolling path;
A ball screw comprising:
The nut has a through-hole penetrating in the radial direction in which the circulating top is disposed, and a counterbored hole formed on the outer diameter side of the through-hole,
The ball screw, wherein the circulating top is fixed to the nut by an adhesive in the counterbored hole or a curable resin.
(8) The ball screw according to (7), wherein the circulating top has a concave groove on an outer surface, and the concave groove is filled with the adhesive or a curable resin.
(9) The counterbore has a fixing groove on an inner surface, and the fixing groove is filled with the adhesive or a curable resin. (7) or (8) Ball screw.
(10) The ball screw according to any one of (7) to (9), wherein the curable resin is an epoxy resin or a two-component epoxy resin.

  According to the ball screw nut manufacturing method and the ball screw of the present invention, the nut forms a through-hole and a counterbore hole penetrating in the radial direction at a position where the ball return passage of the nut is provided, and the inner periphery of the nut Position the circulating top in contact with the positioning jig placed on the surface and position the circulating top inserted in the through hole with respect to the nut. Pour the adhesive or curable resin into the counterbore and harden the circulating top. After being fixed to, the positioning jig is removed from the nut. Therefore, the boundary portion between the thread groove of the nut and the ball return passage of the circulating top can be formed without a step, and vibration generated when the ball passes through the boundary portion between the nut and the circulating top. And noise can be suppressed.

It is a perspective view of a ball screw concerning a 1st embodiment of the present invention. It is explanatory drawing which shows the manufacture procedure of the ball screw of FIG. It is a perspective view of the nut of the ball screw of a 2nd embodiment. (A) is a perspective view of the nut of the ball screw of the 1st modification, (b) is a perspective view of the nut of the ball screw of the 2nd modification. (A) is a perspective view of the nut of the ball screw of a 3rd modification, (b) is a perspective view of the nut of the ball screw of a 4th modification.

  Hereinafter, a ball screw nut manufacturing method and a ball screw according to each embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the internal circulation type ball screw 1 of the first embodiment is used for conveyance and precision positioning of machine tools, industrial machines, etc., and in particular, high-precision processing such as mold processing. It is suitably used for high-precision machine tools used in

  The ball screw 1 includes a screw shaft 10, a nut 20, a plurality of balls 30, and a plurality of circulating tops 40. The screw shaft 10 is formed in a cylindrical shape centered on the central axis CL, and a spiral first screw groove 11 having a predetermined lead is formed on the outer peripheral surface thereof.

  The nut 20 has a substantially cylindrical shape, and an inner diameter thereof is formed to be larger than an outer diameter of the screw shaft 10. The nut 20 is externally fitted to the screw shaft 10 with a predetermined gap. One end of the nut 20 is provided with a flange 25 for coupling with the object to be guided. On the inner peripheral surface of the nut 20, a second screw groove 21 having a lead equal to the first screw groove 11 of the screw shaft 10 and facing the first screw groove 11 is formed. A rolling path (not shown) having a substantially circular cross section is formed by the first thread groove 11 of the screw shaft 10 and the second thread groove 21 of the nut 20. A plurality of balls 30 are filled in the rolling path so as to roll.

  A plurality of circulation tops 40 are mounted on the inner peripheral surface of the nut 20 to return the balls 30 to the rolling path on the near side. Each circulation top 40 is formed in a substantially cylindrical shape so that the maximum outer diameter corresponds to the inner diameter of a circular through hole 23 described later. A substantially S-shaped ball return passage 42 that connects one end of the rolling path and the other end of the rolling path immediately before the winding is formed on the inner surface of each circulation top 40. By this ball return passage 42, the ball 30 rolling on the rolling path toward each circulation top 40 is scooped up in the radial direction of the screw shaft 10, and further over the thread 12 of the screw shaft 10, and one roll before ( The ball 30 can be circulated by returning it to the rolling path just before the lead.

  The ball return passage 42 and the rolling path form a substantially annular infinite circulation path (not shown) outside the screw shaft 10. As a result, the plurality of balls 30 endlessly circulate in the endless circulation path with the relative rotation of the screw shaft 10 with respect to the nut 20, so that the nut 20 and the screw shaft 10 are relative to each other in the axial direction of the screw shaft 10. Can be linearly moved.

  Next, a method for manufacturing the nut 20 including the second screw groove 21 and the ball return passage 42 will be described with reference to FIG. In the method of manufacturing the nut 20 according to the present embodiment, the circulating top 40 in which the ball return passage 42 is formed is positioned on the nut 20 using the positioning jig 50, and then the circulating top 40 is nuts with an adhesive or a curable resin 61. This is a method of installing on the nut 20 so that the boundary between the second screw groove 21 and the ball return passage 42 is connected to the step 20 without any step.

  As shown in FIG. 2A, first, the positioning jig 50 is inserted inside the nut 20. As described above, in the nut 20, the second screw groove 21 is formed on the inner peripheral surface of the nut 20 having the flange 25, and the through-hole 23 penetrates in the radial direction at a position where the ball return passage 42 is formed. And a counterbore hole 24 formed on the outer diameter side of the through hole 23 is formed. In the embodiment shown in FIG. 2A, the through hole 23 is a round hole, and the counterbore hole 24 has an opposing surface having a width equal to or larger than the outer diameter of the through hole 23 and is larger than the through hole 23. It is a hole.

  The positioning jig 50 includes a semi-cylindrical positioning portion 51 for positioning the ball return passage 42 of the circulating top 40 with respect to the second screw groove 21 of the nut 20, and the positioning portion 51 for operating the positioning jig 50. And a grip portion 54 extending from the shaft.

The positioning portion 51 has a thread groove fitting portion 52 having a shape copied from the shape of the second screw groove 21 and a ball return passage fitting having a shape copied from the shape of the ball return passage 42 of the circulating top 40. Part 53 is provided.
A circular peripheral portion 55 corresponding to the through hole 23 other than the ball return passage fitting portion 53 is formed corresponding to the inner surface of the circulation top 40 other than the ball return passage 42.

  The positioning portion 51 of the positioning jig 50 is formed corresponding to the inner peripheral surface shape around the through hole 23, and is smaller than the inner diameter of the second screw groove 21 of the nut 20. Thereby, the positioning part 51 is movable in the axial direction and the radial direction on the inner diameter side of the second screw groove 21 formed in the nut 20. Note that the shape of the positioning portion 51 of the present embodiment is not limited to this as long as the shape of the inner peripheral surface around the through-hole 23 corresponds, or may be smaller than the semi-cylindrical shape, or may be a cylindrical shape. It may be.

  Next, a substantially cylindrical circulation top 40 having a substantially S-shaped ball return passage 42 is fitted into the through hole 23 of the nut 20. The circulation top 40 can move in the radial direction of the nut 20 in the through hole 23, and an annular concave groove 43 is formed on the outer surface thereof. The concave groove 43 is preferably formed at a position where the concave groove 43 is exposed in the counterbore 24 when the circulating top 40 is fitted into the through hole 23.

  Then, the positioning portion 51 of the positioning jig 50 is inserted inside the second screw groove 21 of the nut 20 and further moved in the radial direction, and the screw groove fitting portion 52 of the positioning portion 51 is fitted into the second screw groove 21. At the same time, the ball return passage 42 of the circulation top 40 is fitted to the ball return passage fitting portion 53 of the positioning portion 51 to position the circulation top 40.

  In this way, the screw groove fitting portion 52 and the ball return passage fitting portion 53 of the positioning jig 50 are fitted in close contact with the second screw groove 21 of the nut 20 and the ball return passage 42 of the circulating top 40, respectively. Thus, the boundary portion between the second screw groove 21 of the nut 20 and the ball return passage 42 of the circulating top 40 is smoothly connected without a step. At this time, the concave groove 43 of the circulating top 40 protrudes from the through hole 23 into the counterbore 24.

  Next, as shown in FIG. 2 (b), an adhesive prepared in the container 60 or a curable resin 61 is poured into the counterbore 24 and cured. Then, after the adhesive or the curable resin 61 is sufficiently cured, the positioning jig 50 is removed from the nut 20 to smoothly connect the boundary between the second screw groove 21 and the ball return passage 42 without any step. The nut 20 having the rolled path is manufactured.

  Since the adhesive or the curable resin 61 is also filled into the concave groove 43 of the circulating top 40 and hardened, the circulating top 40 can be firmly fixed to the nut 20 not only by adhesion but also mechanically. . As a result, the circulation top 40 can be securely fixed to the nut 20 even if it is a metal circulation top 40 or a polyacetal circulation top 40 that is difficult to bond, in addition to the synthetic resin. .

  The curable resin 61 is preferably an epoxy resin or a two-component epoxy resin from the viewpoint of strength and moldability.

  As described above, according to the ball screw nut manufacturing method and the ball screw of the present embodiment, the nut 20 includes the through-hole 23 penetrating in the radial direction at a position where the ball return passage 42 of the nut 20 is provided. A counterbore hole 24 is formed, and the circulating top 40 is brought into contact with a positioning jig 50 disposed on the inner peripheral surface of the nut 20 to position the circulating top 40 inserted into the through hole 23 with respect to the nut 20. After the adhesive or curable resin 61 is poured into the hole 24 and cured to fix the circulating top 40 to the nut 20, the positioning jig 50 is removed from the nut 20. Therefore, the boundary portion between the thread groove 21 of the nut 20 and the ball return passage 42 of the circulating top 40 can be smoothly connected without any step, whereby the ball 30 is connected to the boundary between the nut 20 and the circulating top 40. It is possible to suppress local increases in vibration, noise, and torque that occur when passing through the section.

  Further, the positioning jig 50 is arranged on the inner peripheral surface of the nut 20 by fitting the screw groove fitting portion 52 in which the shape of the second screw groove 21 of the nut 20 is copied into the second screw groove 21. Therefore, the positional accuracy of the positioning jig 50 with respect to the nut 20 is improved.

  Further, since the circulation top 40 is positioned by fitting the ball return passage 42 to the ball return passage fitting portion 53 formed in the positioning jig 50, the position of the circulation top 40 with respect to the nut 20 is accurately determined. Can be positioned.

  Moreover, since the circulation top 40 is provided with the concave groove 43 on the outer surface and the concave groove 43 is filled with the adhesive or the curable resin 61, the circulation top 40 can be firmly fixed to the nut 20.

  Furthermore, since the curable resin is an epoxy resin or a two-component epoxy resin, the circulating top 40 can be more firmly fixed to the nut 20.

(Second Embodiment)
Next, a ball screw nut manufacturing method and a ball screw according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment differs from the nut 20 of the first embodiment in that a fixing groove 26 is formed on the inner surface of the counterbore hole 24. The other parts, including the positioning jig 50, are the same as those in the first embodiment, and thus the description thereof is omitted.

In the second embodiment, a pair of fixing grooves 26 is formed along the longitudinal direction on both opposing flat side surfaces of the counterbore hole 24 (only one is shown in the figure). Also in the manufacturing method of the present embodiment, the adhesive or the curable resin 61 is poured into the counterbore 24 around the circulation top 40 and cured with the concave groove 43 protruding from the through hole 23. Since the adhesive or the curable resin 61 is filled and cured in the concave groove 43 of the circulating top 40 and the fixing groove 26 of the counterbore hole 24, the circulating top 40 is more firmly fixed to the nut 20 and the through hole is formed. 23 can be prevented from falling off.
Other configurations and operations are the same as those in the first embodiment.

In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.
For example, in the above embodiment, the counterbore hole 24 is oval, but the counterbore hole 24A is coaxial with the through-hole 23 and larger than the through-hole 23 as in the modification shown in FIG. May be. Further, as in the modification shown in FIG. 4B, even in the case of a circular counterbore 24A, a pair of fixing grooves 26 (see FIG. Then, only one side may be formed.

  Further, in the above embodiment, the through hole 23 is circular and the counterbore hole 24 is oval. However, as in the modification shown in FIG. It may be inclined, in other words, a long hole having a long axis in the axial direction of the ball return passage 42, and the counterbore hole 24A may be circular. Also in this case, a pair of fixing grooves 26 may be formed on the side surface of the counterbore hole 24A as in the modification shown in FIG.

1 Ball screw 10 Screw shaft 11 First thread groove (thread groove)
20 Nut (ball screw nut)
21 Second thread groove (thread groove)
23, 23A Through hole 24, 24A Counterbore 30 Ball 40 Circulation top 42 Ball return passage 43 Recess groove 50 Positioning jig 52 Screw groove fitting portion 53 Ball return passage fitting portion 61 Curable resin

Claims (10)

A method for producing a nut for a ball screw, wherein a circulating top having a ball return passage connected to the thread groove is installed in a nut having a spiral thread groove formed on an inner peripheral surface,
Preparing the nut having a through-hole formed in a radial direction at a position where the ball return passage is provided and a counterbore hole formed on the outer diameter side of the through-hole;
Placing a positioning jig on the inner peripheral surface of the nut where the through hole opens;
Contacting the circulating top with the positioning jig and positioning the circulating top inserted into the through hole with respect to the nut;
A step of pouring an adhesive or a curable resin into the counterbored holes and curing, and fixing the circulating top to the nut;
Removing the positioning jig from the nut;
A method for producing a ball screw nut, comprising:   The positioning jig is arranged on an inner peripheral surface of the nut by fitting a screw groove fitting portion in which the shape of the screw groove of the nut is copied into the screw groove. 2. A method for producing a ball screw nut according to 1.   The circulation top is positioned by fitting the ball return passage into a ball return passage fitting portion formed on the positioning jig and having a copy of the shape of the ball return passage. The method for producing a nut for a ball screw according to claim 1 or 2.   The said circulation top is provided with the ditch | groove on the outer surface, The said adhesive agent or curable resin is filled in this ditch | groove, The Claim 1 characterized by the above-mentioned. A method for producing a nut for a ball screw.   5. The counterbore according to claim 1, wherein the counterbore hole includes a fixing groove on an inner surface, and the adhesive or the curable resin is filled in the fixing groove. Of manufacturing nuts for ball screws.   The method for producing a nut for a ball screw according to any one of claims 1 to 5, wherein the curable resin is an epoxy resin or a two-component epoxy resin. A screw shaft having a helical thread groove formed on the outer peripheral surface;
A nut disposed around the screw shaft and having a helical thread groove formed on the inner peripheral surface;
A plurality of balls accommodated in a rolling path formed by opposing screw grooves;
A circulation top attached to the nut and having a ball return passage for circulation from one end to the other end of the rolling path;
A ball screw comprising:
The nut has a through-hole penetrating in the radial direction in which the circulating top is disposed, and a counterbored hole formed on the outer diameter side of the through-hole,
The ball screw, wherein the circulating top is fixed to the nut by an adhesive in the counterbored hole or a curable resin.   The ball screw according to claim 7, wherein the circulation top has a concave groove on an outer surface, and the adhesive or curable resin is filled in the concave groove.   The ball screw according to claim 7 or 8, wherein the counterbore has a fixing groove on an inner surface, and the adhesive or curable resin is filled in the fixing groove.   The ball screw according to claim 7, wherein the curable resin is an epoxy resin or a two-component epoxy resin.

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