JP2023158726A - Manufacturing method of ball screw nut and ball screw - Google Patents

Abstract

The present invention provides a method for manufacturing a nut for a ball screw and a ball screw that can suppress vibration and noise generated when a ball passes through a boundary between a nut and a stop.
[Solution]
The nut 20 of the ball screw 1 has a through hole 23 that penetrates in the radial direction at the position where the ball return passage 42 of the nut 20 is provided, and the circulation piece 40 is inserted into the through hole using an insertion jig 50 and a reference jig 60. 23, and the adhesive G is poured into the through hole 23 from which the insertion jig 50 and the reference jig 60 have been removed and cured.
[Selection diagram] Figure 1

Description

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

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

In a top-type ball screw, a ball return passage is formed that connects leads adjacent to the top, and the balls circulate through the ball return passage while riding over the outer diameter of the screw shaft. In addition, ball screw nuts are generally made of metal or resin, and have a ball return path that is assembled into the nut and fixed with adhesive to circulate the balls. , the outer diameter of the nut can be made compact.

On the other hand, with a top-type ball screw, there may be a large step at the boundary between the ball return path of the top and the ball groove of the nut, which may cause vibrations or local torque when the ball passes through the step. There are concerns about problems such as an increase in Additionally, because the tops are fixed with adhesive, it is difficult to adjust the level difference and reassemble the tops.

Therefore, various shapes have been considered to eliminate this assembly error.

JP2019-203590

In the top-type ball screw described in Patent Document 1, the circulation top is positioned using a jig that fits into a groove, and an adhesive is applied in the positioned state to fix the circulation top. However, there were problems with this method, such as poor workability when fixing the circulating top with the jig applied, and the hole in the nut into which the circulating top was inserted had a counterbore shape, increasing processing costs.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a ball screw that can suppress vibration and noise generated when the ball passes through the boundary between the nut and the stopper. An object of the present invention is to provide a method for manufacturing a nut and a ball screw.

The above object of the present invention is achieved by the following configuration.
(1) A method for manufacturing a ball screw nut, in which a circulation piece having a ball return passage connected to the thread groove is installed in a nut having a spiral thread groove formed on the inner circumferential surface, the method comprising:
preparing the nut having a radially penetrating through hole formed at a position where the ball return passage is provided;
inserting a circulation top into the through hole;
inserting an insertion jig for pushing the circulation top;
pressing a reference jig for pushing the insertion jig into the through hole of the nut to press fit the circulation top;
removing the reference jig and the insertion jig from the nut;
pouring an adhesive into the through hole and curing it to fix the circulation top to the nut;
Equipped with
The circulating top fits a fitting portion of a contact surface with the insertion jig into a fitting receiving portion of a contact surface of the insertion jig with the circulation top,
The insertion jig fits a fitting portion of a contact surface with the reference jig into a fitting receiving portion of a contact surface of the reference jig with the insertion jig,
The method for manufacturing a nut for a ball screw, wherein the reference jig has an abutting portion that comes into contact with an outer circumferential surface of the nut to determine a press-fitting position of the circulation piece.
(2) The method for manufacturing a ball screw nut according to (1), wherein a groove is provided on the circumferential surface of the through hole of the nut, and the groove is filled with the adhesive.
(3) A method for manufacturing a ball screw nut, in which a circulation piece having a ball return passage connected to the thread groove is installed in the nut having a spiral thread groove formed on the inner circumferential surface, the method comprising:
preparing the nut having a radially penetrating elongated hole formed at a position where the ball return passage is provided;
inserting a circulation piece that fits and is press-fitted into the elongated through hole;
inserting an insertion jig for pushing the circulation top;
Pressing a reference jig into which the insertion jig is pushed into the elongated through hole of the nut to press fit the circulation top;
pouring adhesive into the elongated through hole and curing it to fix the circulation top to the nut;
removing the reference jig and the insertion jig from the nut;
A method for manufacturing a ball screw nut, comprising:
(4) The nut for a ball screw according to (3), wherein a groove is provided on the circumferential surface of the elongated through hole of the nut, and the groove is filled with the adhesive. Production method.
(5) Manufacturing a ball screw nut according to any one of (1) to (4), wherein the adhesive is a moisture-curable adhesive, an ultraviolet-curable adhesive, or an epoxy adhesive. Method.

(6) a screw shaft with a spiral thread groove formed on its outer peripheral surface;
a nut arranged around the screw shaft and having a spiral thread groove formed on its inner peripheral surface;
a plurality of balls accommodated in a rolling path formed by both opposing thread grooves;
a circulation top that is attached to the nut and has a ball return path for circulating the rolling path;
A ball screw comprising:
The nut has a through hole that penetrates in the radial direction,
The circulation top is press-fitted into the through hole by an insertion jig and a reference jig, and the circulation top held in the through hole is fixed to the nut by an adhesive in the through hole,
The circulation top includes an outer circumferential surface that fits into a circumferential surface of the through hole, and a fitting portion on a surface that comes into contact with the insertion jig,
The insertion jig includes a fitting receiving part that fits with a fitting part of the circulating top on a surface that comes into contact with the circulating top, and a fitting part on a surface that comes into contact with the reference jig,
The reference jig includes a fitting receiving part that fits with a fitting part of the insertion jig on a surface that comes into contact with the insertion jig,
The ball screw is characterized in that the reference jig includes a contact portion that comes into contact with the outer circumferential surface of the nut to determine a press-fitting position of the circulation piece.
(7) The circulation piece is characterized in that the hole circumferential surface of the through hole of the nut is provided with a concave groove filled with the adhesive, and the circulation piece has a fitting portion on the surface that comes into contact with the insertion jig. The ball screw according to item (6), wherein the insertion jig is provided with a fitting receiving portion that fits into a fitting portion of the circulating top on a surface that comes into contact with the circulating top.
(8) a screw shaft with a spiral thread groove formed on its outer peripheral surface;
a nut arranged around the screw shaft and having a spiral thread groove formed on its inner peripheral surface;
a plurality of balls accommodated in a rolling path formed by both opposing thread grooves;
a circulation top that is attached to the nut and has a ball return path for circulating the rolling path;
A ball screw comprising:
The nut has an elongated through hole that penetrates in the radial direction,
The circulation top has an outer peripheral surface that fits into the hole circumferential surface of the through-hole, and is press-fitted into the through-hole by an insertion jig and a reference jig, and the circulation top is retained in the through-hole. is fixed to the nut by an adhesive in the elongated through hole.
(9) The ball screw according to (8), wherein the hole circumferential surface of the elongated through hole of the nut is provided with a groove filled with the adhesive.
(10) The ball screw according to any one of (6) to (9), wherein the adhesive is a moisture-curable adhesive, an ultraviolet-curable adhesive, or an epoxy adhesive.

According to the present invention, it is possible to provide a method for manufacturing a nut for a ball screw and a ball screw that can suppress vibrations and noise generated when the balls pass through the boundary between the nut and the stop.

FIG. 2 is an explanatory diagram of a ball screw according to a first embodiment of the present invention, in which (a) is an explanatory perspective view showing the insertion order of the circulation top insertion jig and the reference jig, and (b) is an explanatory perspective view showing the insertion order of the circulation top insertion jig and the reference jig. (c) is an explanatory perspective view showing a state in which the nut is in contact with the outer circumferential surface of the nut, and (c) is an explanatory perspective view showing a state in which adhesive is poured. It is three views which show a reference jig, (a) is a top view, (b) is a side view, and (c) is a bottom view. FIG. 4 is a four-sided view showing the insertion jig, in which (a) is a plan view, (b) is a side view, (c) is a bottom view, and (d) is a side view seen from another direction. It is three views which show a circulating top, (a) is a top view, (b) is a side view, and (c) is a bottom view. FIG. 3 is an explanatory diagram showing a modified example of the first embodiment of the present invention, in which (a) is an explanatory perspective view showing a groove in a through hole of a nut, and (b) is an explanatory perspective view showing a groove in a through hole of a nut; It is a sectional view showing a filled state. FIG. 7 is an explanatory perspective view showing the order of insertion of a circulating top insertion jig and a reference jig for a ball screw according to a second embodiment of the present invention. It is three views which show a reference jig, (a) is a top view, (b) is a side view, and (c) is a bottom view. It is a two-sided view which shows an insertion jig, (a) is a top view, (b) is a side view. It is three views which show a circulating top, (a) is a top view, (b) is a side view, and (c) is a bottom view. FIG. 6 is an explanatory diagram showing a modification of the second embodiment of the present invention, in which (a) is an explanatory perspective view showing a groove in a through hole of a nut, and (b) is an explanatory perspective view showing a groove in a through hole of a nut; It is a sectional view showing a filled state.

Hereinafter, a method for manufacturing a ball screw nut and an embodiment of the ball screw according to the present invention will be described. Note that this embodiment is only one embodiment of the present invention and should not be construed as limiting in any way, and the design can be changed as appropriate within the scope of the present invention.

(First embodiment)
The ball screw 1 has a screw shaft (not shown) having a helical thread groove formed on its circumferential surface, and is externally fitted onto the screw shaft with a predetermined gap, and has a helical thread groove 21 formed on its inner circumferential surface 27. It consists of a substantially cylindrical nut 20 (FIG. 1(a)) and a plurality of balls (not shown) accommodated in a rolling path formed by both opposing thread grooves.
Further, a flange 25 is provided at one end of the nut 20, and guides a guided object coupled to the flange 25 along with the linear movement of the nut 20.

Further, the nut 20 includes a plurality of perfectly circular through holes 23 that penetrate in the radial direction from the outer circumferential surface 26 to the inner circumferential surface 27, and a circulation piece 40 is press-fitted into each of the plurality of through holes 23.
As shown in FIG. 4, the circulation top 40 is formed into a disk shape with an outer circumferential surface 43 having a diameter that is in contact with the hole circumferential surface of the circular through hole 23 of the nut 20, and an inner surface 41 thereof (the inner surface 41 of the nut 20). A substantially S-shaped ball return passage 44 is formed on the inner surface of the nut 20 when the nut 20 is press-fitted into the through hole 23 .
The circulation top 40 includes a fitting portion 45 on its outer surface 42 (the surface that becomes the outer diameter side of the nut 20 when inserted into the through hole 23 of the nut 20).
The fitting portion 45 is formed integrally with the outer surface 42 and extends to have a smaller diameter than the outer circumferential surface 43 .
Further, the circumferential surface 45d of the fitting portion 45 is provided with a pair of flat surfaces 45a and 45b cut out and arranged in parallel, and a groove 45e carved in the direction of the outer surface 42 from the end surface 45c of the small diameter portion. Be prepared. Further, the positions of the pair of plane parts 45a and 45b are such that when the ball return passage 44 of the inner surface 41 is press-fitted with a fitting receiving part 53 of an insertion jig 50, which will be described later, The direction is set to be continuous with the spiral thread groove 21 of the surface 27.

The circulation piece 40 is press-fitted into the through hole 23 of the nut 20, and the ball return passage 44 of the circulation piece 40 is continuous with the inner diameter surface of the nut 20, and is connected to one end of the thread groove (rolling path) on the inner diameter surface of the nut 20. Connect with the other end of the thread groove (rolling path) one turn before.
With this configuration, the balls rolling between the rolling path (not shown) on the outer circumferential surface of the screw shaft and the rolling path (not shown) on the inner circumferential surface of the nut 20 are circulated. The ball is scooped up by the ball return passage 44 of the top 40 and returned to the rolling path one turn before (one lead before), making it possible to circulate endlessly, and the nut 20 and the screw shaft move relatively linearly in the axial direction. becomes possible.
That is, in order for the nut 20 and the screw shaft to move linearly smoothly, when manufacturing the nut, the ball return passage 44 of the circulation piece 40 must be continuous with the spiral thread groove 21 on the inner peripheral surface 27 of the nut 20. In order to do this, it is required to position the circulation top 40 at a predetermined depth and in a predetermined direction in the through hole 23 of the nut 20.

The insertion jig 50 is formed into a cylindrical shape with a diameter slightly smaller than the diameter of the through hole 23 of the nut 20 (FIG. 3).
The inner surface 51 (the surface that becomes the outer diameter side of the nut 20 when inserted into the through hole 23 of the nut 20) has a radial direction (the surface that becomes the radial direction of the nut 20 when inserted into the through hole 23 of the nut 20). A fitting receiving portion 53 is recessed in the direction). Further, the engraving depth of the fitting receiving portion 53 is set to be deeper than the extending height of the fitting portion 45 of the circulation top 40.
The fitting receiving portion 53 further includes a pair of linear inner walls 53a and 53b formed in parallel with each other. Further, the distance between the inner wall 53a and the inner wall 53b is set to be slightly larger than the distance between the flat portion 45a and the flat portion 45b of the fitting portion 45 of the circulation top 40.
A fitting portion 54 is provided on the outer surface 51 of the insertion jig 50 (the surface that becomes the outer diameter side of the nut 20 when inserted into the through hole 23 of the nut 20).
The fitting portion 54 is formed integrally extending from the outer surface 51 in a plate shape. In addition, the direction of the plate surface of the plate-shaped fitting part 54 is such that when it is fitted with a groove-shaped receiving part 64 of a reference jig 60, which will be described later, the ball return passage 44 of the inner surface 41 of the circulation piece 40 is aligned with the nut 20. It is set so as to be continuous with the spiral thread groove 21 on the inner circumferential surface 27.

As shown in FIG. 2, the reference jig 60 is formed into a substantially rectangular parallelepiped shape, and a recess 62 having a curvature similar to the curvature of the outer peripheral surface 26 of the nut 20 is carved in the lower surface 61 of the reference jig 60.
Further, a fitting receiving part 65 is carved in the deepest part 62a of the recess 62 of the reference jig 60.
The fitting receiving part 65 includes a circular receiving part 63 that is carved as a circular hole at a predetermined depth from the concave curved surface 62b of the recessed part 62 toward the upper surface 65, and a circular receiving part 63 that penetrates the circular receiving part 63 and the upper surface 65. A groove-shaped receiving portion 64 is formed.
The circular receiving portion 63 is carved as a circular hole at a predetermined depth from the concave curved surface 62b of the recessed portion 62 toward the upper surface 65, and has a diameter slightly larger than the diameter of the insertion jig 50 on the peripheral wall surface 63a. It is set so that

Further, the size of the groove-shaped receiving portion 64 is set to be a slot slightly larger than the plate-shaped fitting portion 54 of the insertion jig 50.
Further, the length of the circulation top 40 and the insertion jig 50 (the length in the radial direction of the nut 20) is such that the fitting portion 45 of the circulation top 40 and the fitting receiving portion 53 of the insertion jig 50 are fitted together. When the fitting part 54 of the insertion jig 50 and the fitting receiving part 65 of the reference jig 60 are fitted together, the predetermined depth of the through hole 23 of the nut 20 (the ball return passage 44 is set to be a depth that is continuous with the spiral thread groove 21 on the inner circumferential surface 27 of the nut 20.

Next, the process of fixing the circulation piece 40 to the through hole 23 of the nut 20 will be explained.
In this embodiment, an insertion jig 50 and a reference jig 60 are used, and the circulating top 40 is pushed into the insertion jig 50, and the reference jig 60 determines the depth to which the circulating top 40 is inserted. Then, the circulation top 40 is press-fitted into the through hole 23 of the nut 20 at a predetermined depth (FIG. 1).
Specifically, a first step of preparing the nut 20, a second step of inserting the circulation piece 40 into the through hole 23, and a second step of inserting the insertion jig 50 into the through hole 23 into which the circulation piece 40 has been inserted. a fourth step in which the reference jig 60 is pressed against the through hole 23 into which the circulation top 40 and the insertion jig 50 have been inserted; and a fifth step in which the reference jig 60 and the insertion jig 50 are removed from the nut 20. and a sixth step of pouring adhesive G into the through hole 23 and curing it to fix the circulation piece to the nut.

The nut 20 prepared in the first step is in an unfinished state as the circulation piece 40 is not fixed to the through hole 23 (see FIG. 1(a)).
Next, in a second step, the circulation top 40 is inserted into the through hole 23 so that its inner surface 41 is in the direction of the inner peripheral surface 27 of the nut 20 (FIG. 1(a)). At this time, since the outer diameter of the circulation top 40 is set to a diameter that is in contact with the hole circumferential surface of the circular through hole 23 of the nut 20, it does not pass through the through hole 23 and fall. It is pushed in, but it does not reach the designated position.

Next, in a third step, the insertion jig 50 is inserted into the through hole 23 so that its inner surface 51 is oriented toward the inner peripheral surface 27 of the nut 20 (FIG. 1(a)). At this time, the inner walls 53a and 53b of the fitting receiving part 53 provided on the inner surface 51 of the insertion jig 50 are set so as to fit with the pair of flat parts 45a and 45b of the fitting part 45 provided on the outer surface 42 of the circulation top 40. do. By fitting together in this manner, the circulation piece 40 becomes integral with the insertion jig 50 so as not to rotate in the circumferential direction (the circumferential direction of the circular through hole 23 of the nut 20).
At this time, since the circulation top 23 has not yet been set in the predetermined position, the outer surface 52 of the insertion jig 50 fitted with the circulation top 40 is different from when the circulation top 23 is set in the predetermined position. It is in a state in which a large amount protrudes from the outer circumferential surface 26 of the nut 20.

Next, in a fourth step, the reference jig 60 is placed on the outer circumferential surface 43 of the nut 20 so that the fitting receiving part 65 of the lower surface 61 of the reference jig 60 is fitted with the insertion jig 50. set.
At this time, the circumferential surface of the insertion jig 50 on the outer surface 52 side fits into the circular receiving part 63 of the reference jig 60, and the groove-shaped receiving part 64 of the reference jig 60 fits into the circular receiving part 63 of the insertion jig 50. A fitting portion 54 extending in a plate shape from the outer surface 52 fits into each other. By fitting together in this manner, the insertion jig 50 becomes integral with the reference jig 60 so as not to rotate in the circumferential direction (the circumferential direction of the circular through hole 23 of the nut 20).
Furthermore, due to the fitting between the reference jig 60 and the insertion jig 50 and the fitting between the insertion jig 50 and the circulation piece 40, the circulation piece 40 is moved in the circumferential direction (around the circumference of the circular through hole 23 of the nut 20). direction).

Further, in the fourth step, pressure is applied in the direction of the inner peripheral surface 27 of the reel 2 so as to press the reference jig 60 against the through hole 23 of the reel 2, so that the concave curved surface 62b of the reference jig 60 is pressed against the through hole 23 of the reel 2. (See FIG. 1(b)).
At this time, the concave curved surface 62b functions as a contact part that determines the position where the circulating top 40 is press-fitted, and is pressed against the through hole 23 of the reel 20, and the circulating top 40 follows the pushing of the reference jig 60. By being pushed by the insertion jig 50, the circulating top 40 is press-fitted into the through hole 23 to a predetermined position.
As a result, the ball return passage 44 of the circulation top 40 is press-fitted to a depth such that it is continuous with the spiral thread groove 21 of the inner peripheral surface 27 of the nut 20, and the direction of the ball return passage 44 of the nut 20 is changed. It is set so as to be continuous with the spiral thread groove 21 on the inner circumferential surface 27.

In the fifth step, the reference jig 60 is removed from the nut 20, and the insertion jig 50 is pulled out from the through hole 23 of the nut 20.
Furthermore, in the sixth step, the adhesive G is poured into the through hole 23 until it becomes substantially flush with the outer circumferential surface 43 of the nut 20 and hardened. As a result, the circulation top 40 is fixed at a predetermined position in the through hole 23 (FIG. 1(c)).

At this time, since the outer circumferential surface 43 of the circulation top 40 is press-fitted into the through hole 23 of the nut 20, there is no gap between the outer circumferential surface 43 and the through hole 23, and the poured adhesive G is applied to the inner circumference of the nut 20. The adhesive G does not ooze out onto the surface 27, and therefore the spiral thread groove 21 of the nut 20 and the ball return passage 44 of the circulation piece 40 are not damaged by the adhesive G.
In this embodiment, the adhesive G is assumed to be a moisture-curable adhesive, an ultraviolet-curable adhesive, an epoxy adhesive, etc., and as a result, the adhesive poured into the through hole 23 can be used at any timing. It becomes possible to harden and improve work efficiency.

In this embodiment, the fitting portion 45 of the circulation top 40 fits into the fitting receiving portion 53 of the insertion jig 50, and the fitting portion 54 of the insertion jig 50 fits into the fitting receiving portion (circular receiving portion) of the reference jig 60. 63 and the groove-shaped receiving part 64), the arrangement of the fitting part and the fitting receiving part is not limited to this. , any other arrangement may be used as long as it can be press-fitted into the predetermined position of the through hole 20. For example, the insertion jig 50 side may be provided with a fitting portion that fits into the circulation top 40, or the reference jig 60 side may be provided with a fitting portion that fits into the insertion jig 50. However, it is within the scope of the present invention.

(Modified example)
As a modification of this embodiment, the through hole 23 of the nut 20 may be provided with a groove 28 on the hole circumferential surface 23a (cylindrical wall surface of the through hole 23). For example, as shown in FIG. 5, the groove 28 may include a pair of grooves 28a and 28b facing each other and expanding in the radial direction of the hole from the circumferential surface 23a.
By providing a pair of opposing grooves 28a and 28b in this manner, the adhesive G poured into the through hole 23 also flows into the grooves 28a and 28b. As the adhesive G hardens, a flange of the hardened adhesive G is formed in the concave grooves 28a and 28b, and the effect of preventing the adhesive G from moving and coming off from the through hole 23 is strengthened.
Furthermore, regarding the depth of the grooves 28a and 28b, the depth of each groove is set to be at least two depths relative to the diameter of the through hole 23, that is, at least half the diameter of the through hole 23. preferable.

(Second embodiment)
In this embodiment, the general configuration for press-fitting the circulation piece 40 into the through hole 23 of the nut 20 using the insertion jig 50 and the reference jig 60 is the same, so a detailed explanation of the same configuration will be given here. This will be omitted, and the explanation will focus on the different configurations.
In the first embodiment, the nut 20 was formed with a circular through hole (see FIG. 1), but in the nut 20 of this embodiment, a long through hole 23 (see FIG. 6) was formed.

As shown in FIG. 9, the circulation top 40 is formed into an oval shape with an outer peripheral surface 43 having a shape that is in contact with the hole peripheral surface of the elongated through hole 23 of the nut 20, and an inner surface 41 (the through length of the nut 20). A substantially S-shaped ball return passage 44 is formed on the inner surface of the nut 20 when the nut 20 is press-fitted into the hole 23. Regarding the direction in which the ball return passage 44 is formed, when the circulation piece 40 is set in the predetermined position of the through hole 23 of the nut 20, the ball return passage 44 of the inner surface 41 is formed in the direction that the ball return passage 44 of the inner surface 27 of the nut 20 is formed. It is set so as to be continuous with the spiral thread groove 21.
The outer surface 42 of the circulation top 40 was formed with a fitting part in the first embodiment (see FIG. 1), but in this embodiment, a fitting part is not formed, and a tapered part is formed on the outer circumferential surface 43 on the outer surface 42 side. 43a is formed. The tapered portion 43a has a hakama shape in which the outer surface 42 is slightly widened.

The insertion jig 50 is formed into a cylindrical shape having the same diameter from the inner surface 51 to the outer surface 52. In addition, the insertion jig of the first embodiment was equipped with a fitting part that fits with the fitting part of the circulating top and a fitting part that fits with the fitting part of the reference jig (see Fig. 1). ), this embodiment does not include a fitting portion or a fitting receiving portion.
The reference jig 60 is formed into a substantially rectangular parallelepiped shape as in the first embodiment, and a recess 62 having a curvature similar to the curvature of the outer circumferential surface 26 of the nut 20 is carved in the lower surface 61 of the reference jig 60 .
Furthermore, a circular receiving part 63 is carved in the deepest part 62a of the recessed part 62 of the reference jig 60.
The circular receiving portion 63 is carved as a circular hole at a predetermined depth from the concave curved surface 62b of the recessed portion 62 toward the upper surface 65, and has a diameter slightly larger than the diameter of the insertion jig 50 on the peripheral wall surface 63a. It is set so that Moreover, although the reference jig of the first embodiment was provided with a groove-shaped receiving part (see FIG. 2), the reference jig 60 of this embodiment is not provided with a groove-shaped receiving part.

In addition, the length of the circulation top 40 and the insertion jig 50 (the length in the radial direction of the nut 20) is such that the circulation top 40 and the insertion jig 50 are inserted into the elongated through hole 23 and pushed in with the reference jig 60. In this state, the circulation top 40 and the nut 20 have a predetermined depth of the elongated through hole 23 (the ball return passage 44 on the inner surface 41 of the circulation top 40 is continuous with the spiral thread groove 21 on the inner surface 27 of the nut 20). depth).

Next, the process of fixing the circulation piece 40 to the elongated through hole 23 of the nut 20 will be explained.
In this embodiment as well, an insertion jig 50 and a reference jig 60 are used as in the first embodiment, and the circulation top 40 is pushed into the insertion jig 50, and the circulation top 40 is By determining the insertion depth, the circulation top 40 is press-fitted into the predetermined depth of the elongated through hole 23 of the nut 20 (FIG. 6).
Specifically, the first step is to prepare the nut 20, the second step is to insert the circulation piece 40 into the long through hole 23, and the insertion jig 50 is inserted into the long hole 23 into which the circulation piece 40 is inserted. a fourth step of pressing the reference jig 60 against the through hole 23 into which the circulation top 40 and the insertion jig 50 have been inserted; and a fourth step of pressing the reference jig 60 and the insertion jig 50 from the nut 20. It consists of a fifth step of removing, and a sixth step of pouring adhesive G into the elongated through hole 23 and curing it to fix the circulating top to the nut.

The nut 20 prepared in the first step is in an unfinished state as the circulation piece 40 is not fixed to the elongated through hole 23.
Next, in a second step, the circulation top 40 is inserted into the elongated through hole 23 so that its inner surface 41 is in the direction of the inner peripheral surface 27 of the nut 20.
At this time, since the outer circumferential surface 43 of the circulation top 40 is formed into an oval shape in contact with the hole circumference of the elongated through hole 23 of the nut 20, simply inserting the circulation top 40 into the elongated through hole 23 allows the circulation top to be removed. The ball return passage 44 on the inner surface 41 is continuous with the spiral thread groove 21 on the inner circumferential surface 27 of the nut 20, and there is no need to set the direction of the circulation piece 40 during work.
Further, the outer peripheral surface 43 of the circulation top 40 is set to a diameter that is in contact with the hole peripheral surface of the elongated through hole 23 of the nut 20, and is further provided with a tapered portion 43a (see FIG. 9(b)), so that the through hole length is It does not pass through the hole 23 and fall, and although it is pushed into the elongated through hole 23, it does not reach a predetermined position.

Next, in a third step, the insertion jig 50 is inserted into the elongated through hole 23 so that its inner surface 51 is in the direction of the inner circumferential surface 27 of the nut 20 (FIG. 6). Note that the circulation top 40 and the insertion jig 50 of this embodiment do not have the fitting structure as in the first embodiment, so in this step, the insertion jig 50 is circulated around its inner surface 51. It is only necessary to push the top 40 so that it comes into contact with the outer surface 42 of the top 40.
At this time, since the circulation top 23 has not yet been set in the predetermined position, the outer surface 52 of the insertion jig 50 is farther away from the outer peripheral surface 26 of the nut 20 than when the circulation top 23 is set in the predetermined position. It is in a very prominent state.

Next, in the fourth step, the reference jig 60 is placed on the outer circumferential surface 43 of the nut 20 so as to overlap, and the insertion jig 50 is inserted into the circular receiving portion 63 formed on the concave curved surface 62b of the lower surface 61 of the reference jig 60. Set it so that it fits on the outer surface 52 of.
At this time, the concave curved surface 62b functions as a contact part that determines the position where the circulating top 40 is press-fitted, and is pressed against the through hole 23 of the reel 20, and following the pushing of the reference jig 60, the circulating top 40 By being pushed by the insertion jig 50, the circulating top 40 is press-fitted to a predetermined position in the elongated through hole 23.
As a result, the ball return passage 44 of the circulation top 40 is press-fitted to a depth such that it is continuous with the spiral thread groove 21 of the inner peripheral surface 27 of the nut 20, and the direction of the ball return passage 44 of the nut 20 is changed. It is set so as to be continuous with the spiral thread groove 21 on the inner circumferential surface 27.

In the fifth step, the reference jig 60 is removed from the nut 20, and the insertion jig 50 is pulled out from the elongated through hole 23 of the nut 20.
Further, in a sixth step, adhesive G is poured into the elongated through hole 23 until it becomes substantially flush with the outer circumferential surface 43 of the nut 20 and hardened. As a result, the circulation top 40 is fixed at a predetermined position in the elongated through hole 23.

At this time, since the outer circumferential surface 43 of the circulation top 40 is press-fitted into the elongated through hole 23 of the nut 20, there is no gap between the outer circumferential surface 43 and the elongated through hole 23, and the poured adhesive G is absorbed into the nut 20. The adhesive G does not ooze out onto the inner circumferential surface 27, and therefore the spiral thread groove 21 of the nut 20 and the ball return passage 44 of the circulation piece 40 are not damaged by the adhesive G.
In this embodiment, the adhesive G is assumed to be a moisture-curable adhesive, an ultraviolet-curable adhesive, an epoxy adhesive, etc., and this allows the adhesive poured into the elongated through hole 23 to be applied at any timing. It can be cured in seconds, making work more efficient.

In this embodiment, the nut 20 is provided with a through hole 23, and an oval-shaped circulation top 40 is used, which has an outer peripheral surface 43 having a shape that is in contact with the hole circumferential surface of the through hole 23. Although the direction of the ball return passage 44 is set to be continuous with the spiral thread groove 21 of the inner peripheral surface 27 of the nut 20, the shape of the through hole of the nut 20 is not limited to this. Other shapes may be used as long as the direction of the ball return passage 44 of the ring top 40 can be set to be continuous with the spiral thread groove 21 of the inner circumferential surface 27 of the nut 20.
For example, the same effects as the present invention can be obtained even when the nut 20 is provided with a diamond-shaped through hole, and the nut 20 is combined with a circulation piece 40 having an outer circumferential surface that contacts the diamond-shaped through hole.

(Modified example)
As a modification of the present embodiment, similarly to the modification of the first embodiment, the elongated through hole 23 of the nut 20 has a concave groove 28 on the hole circumferential surface 23a (cylindrical wall surface of the elongated through hole 23). It's good to be prepared. For example, as shown in FIG. 10, the groove 28 may include a pair of grooves 28a and 28b facing each other and expanding in the radial direction of the hole from the circumferential surface 23a.
By providing the pair of grooves 28a and 28b facing each other in this way, the adhesive G poured into the elongated through hole 23 also flows into the grooves 28a and 28b, thereby preventing the adhesive G from coming off due to hardening. will be strengthened.
Further, regarding the depth of the grooves 28a and 28b, the depth of each groove is set to be at least two times the diameter of the elongated through hole 23, that is, more than half the hole diameter of the elongated through hole 23. It is preferable.

INDUSTRIAL APPLICATION This invention can be utilized for the manufacturing method of the nut for ball screws in general, and ball screws in general.

1 Ball screw 20 Nut 21 Spiral thread groove 23 Through hole 23a Hole circumferential surface 25 Flange 26 Outer circumferential surface 27 Inner circumferential surfaces 28a, 28b Concave groove 40 Circulation piece 41 Inner surface 42 Outer surface 43 Outer circumferential surface 43a Tapered portion of second embodiment 44 Ball return passage 45 Fitting portions 45a, 45b Plane portion (fitting portion)
45c End face 45d of small diameter portion Surrounding surface 45e of small diameter portion Fitting groove 50 Insertion jig 51 Inner surface 52 Outer surface 53 Fitting receiving portions 53a, 53b Inner wall (fitting receiving portion)
54 Fitting part 60 Reference jig 61 Lower surface 62 Recessed part 62a Deepest part 62b Concave curved surface (contact part)
63 Circular receiving part (fitting receiving part)
63a Peripheral wall surface 64 Groove-shaped receiving part (fitting receiving part)
65 Fitting receiving part

Claims (10)

A method for manufacturing a nut for a ball screw, in which a circulation piece having a ball return passage connected to the thread groove is installed in a nut having a spiral thread groove formed on the inner peripheral surface, the method comprising:
preparing the nut having a radially penetrating through hole formed at a position where the ball return passage is provided;
inserting a circulation top into the through hole;
inserting an insertion jig for pushing the circulation top;
pressing a reference jig for pushing the insertion jig into the through hole of the nut to press fit the circulation top;
removing the reference jig and the insertion jig from the nut;
pouring an adhesive into the through hole and curing it to fix the circulation top to the nut;
Equipped with
The circulating top fits a fitting portion of a contact surface with the insertion jig into a fitting receiving portion of a contact surface of the insertion jig with the circulation top,
The insertion jig fits a fitting portion of a contact surface with the reference jig into a fitting receiving portion of a contact surface of the reference jig with the insertion jig,
The method for manufacturing a nut for a ball screw, wherein the reference jig has an abutting portion that comes into contact with an outer circumferential surface of the nut to determine a press-fitting position of the circulation piece. 2. The method of manufacturing a ball screw nut according to claim 1, wherein a groove is provided on a peripheral surface of the through hole of the nut, and the groove is filled with the adhesive. A method for manufacturing a nut for a ball screw, in which a circulation piece having a ball return passage connected to the thread groove is installed in a nut having a spiral thread groove formed on the inner peripheral surface, the method comprising:
preparing the nut having a radially penetrating elongated hole formed at a position where the ball return passage is provided;
inserting a circulation piece that fits and is press-fitted into the elongated through hole;
inserting an insertion jig for pushing the circulation top;
Pressing a reference jig into which the insertion jig is pushed into the elongated through hole of the nut to press fit the circulation top;
pouring adhesive into the elongated through hole and curing it to fix the circulation top to the nut;
removing the reference jig and the insertion jig from the nut;
A method for manufacturing a ball screw nut, comprising: 4. The method of manufacturing a ball screw nut according to claim 3, wherein a groove is provided on the circumferential surface of the elongated through hole of the nut, and the groove is filled with the adhesive. The method for manufacturing a ball screw nut according to any one of claims 1 to 4, wherein the adhesive is a moisture-curable adhesive, an ultraviolet-curable adhesive, or an epoxy adhesive. . A screw shaft with a spiral thread groove formed on the outer peripheral surface,
a nut arranged around the screw shaft and having a spiral thread groove formed on its inner peripheral surface;
a plurality of balls accommodated in a rolling path formed by both opposing thread grooves;
a circulation top that is attached to the nut and has a ball return path for circulating the rolling path;
A ball screw comprising:
The nut has a through hole that penetrates in the radial direction,
The circulation top is press-fitted into the through hole by an insertion jig and a reference jig, and the circulation top held in the through hole is fixed to the nut by an adhesive in the through hole,
The circulation top includes an outer circumferential surface that fits into a circumferential surface of the through hole, and a fitting portion on a surface that comes into contact with the insertion jig,
The insertion jig includes a fitting receiving part that fits with a fitting part of the circulating top on a surface that comes into contact with the circulating top, and a fitting part on a surface that comes into contact with the reference jig,
The reference jig includes a fitting receiving part that fits with a fitting part of the insertion jig on a surface that comes into contact with the insertion jig,
The ball screw is characterized in that the reference jig includes a contact portion that comes into contact with the outer circumferential surface of the nut to determine a press-fitting position of the circulation piece. 7. The ball screw according to claim 6, wherein a circumferential surface of the through hole of the nut is provided with a groove filled with the adhesive. A screw shaft with a spiral thread groove formed on the outer peripheral surface,
a nut arranged around the screw shaft and having a spiral thread groove formed on its inner peripheral surface;
a plurality of balls accommodated in a rolling path formed by both opposing thread grooves;
a circulation top that is attached to the nut and has a ball return path for circulating the rolling path;
A ball screw comprising:
The nut has an elongated through hole that penetrates in the radial direction,
The circulation top has an outer peripheral surface that fits into the hole circumferential surface of the through-hole, and is press-fitted into the through-hole by an insertion jig and a reference jig, and the circulation top is retained in the through-hole. is fixed to the nut by an adhesive in the elongated through hole. 9. The ball screw according to claim 8, wherein the hole circumferential surface of the elongated through hole of the nut is provided with a groove filled with the adhesive. The ball screw according to any one of claims 6 to 9, wherein the adhesive is a moisture-curable adhesive, an ultraviolet-curable adhesive, or an epoxy adhesive.

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