JP7110728B2 - Ball screw nut manufacturing method and ball screw - Google Patents

Description

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

A ball screw is a device that converts rotary motion into linear motion by circulating multiple 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 a ball circulation system for a ball screw include a top system, an end cap system, and an end deflector system.

In a top-type ball screw, the balls circulate while riding over the outer diameter of the screw shaft. Ball screw nuts are generally made of metal or resin, and a top with a ball return path is assembled to the nut and fixed with an adhesive or the like to circulate the balls. , the outer diameter of the nut can be made compact.

On the other hand, in a top-type ball screw, the step at the boundary between the ball return passage of the top and the ball groove of the nut may become large. There are concerns about problems such as an increase in In addition, since the top is fixed with an adhesive or the like, it is difficult to adjust the level difference and reassemble the top.

In the bridge-type ball screw disclosed in Patent Document 1, cushioning members made of separate elastic members are attached to both ends of a bridge member joined to the screw groove of the nut, so that the screw groove of the nut and the ball circulation groove of the bridge member are connected. This reduces the noise and vibration caused by the balls passing through the joints.

JP-A-2004-138179

In the ball screw described in Patent Document 1, a buffer member is inserted between the ball circulation groove of the bridge member and the ball groove of the nut to reduce the adverse effects caused by the step. In addition, the step between the ball circulation groove of the bridge member and the ball groove of the nut cannot be fundamentally eliminated. In addition, there is room for improvement because a space for incorporating the cushioning member is required, which may increase the outer diameter of the nut.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a ball screw capable of suppressing vibration and noise generated when balls pass through the boundary between the nut and the top. The object of the present invention is to provide a method for manufacturing a nut for a ball screw and a ball screw.

The above objects of the present invention are achieved by the following configurations.
(1) A method for manufacturing a ball screw nut, in which a circulating top having a ball return passage connected to the thread groove is installed in the nut having a spiral thread groove formed on the inner peripheral surface,
a step of preparing the nut having a radially penetrating through-hole formed at a position where the ball return passage is provided, and a counterbore formed on the outer diameter side of the through-hole;
arranging a positioning jig on the inner peripheral surface of the nut where the through hole opens;
a step of bringing the circulating top into contact 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 hole and curing the resin to fix the circulating top to the nut;
removing the positioning jig from the nut;
A method for manufacturing a ball screw nut, comprising:
(2) The positioning jig is arranged on the inner peripheral surface of the nut by fitting a thread groove fitting portion, which has a shape of the thread groove of the nut, into the thread groove. The method for manufacturing a ball screw nut according to (1).
(3) The circulating top is configured such that the ball return passage is fitted into a ball return passage fitting portion formed in the positioning jig and having the shape of the ball return passage copied. The method for manufacturing a ball screw nut according to (1) or (2), characterized in that positioning is performed.
(4) Any one of (1) to (3), wherein the circulating top has grooves on its outer surface, and the grooves are filled with the adhesive or curable resin. The method for manufacturing the ball screw nut according to 1.
(5) Any one of (1) to (4), wherein the counterbored hole has a fixing groove on an inner side surface, and the fixing groove is filled with the adhesive or the curable resin. A method for manufacturing a ball screw nut according to any one of the above.
(6) The method for producing a ball screw nut according to any one of (1) to (5), wherein the curable resin is an epoxy resin or a two-liquid epoxy resin.
(7) a screw shaft having a helical thread groove formed on its outer peripheral surface;
a nut arranged around the screw shaft and having a helical 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 attached to the nut and having a ball return passage for circulating from one end to the other end of the rolling path;
A ball screw comprising
The nut has a radially penetrating through-hole in which the circulating element is arranged, and a counterbored hole formed on the outer diameter side of the through-hole,
The ball screw, wherein the circulating block is fixed to the nut by an adhesive or a curable resin in the counterbored hole.
(8) The ball screw according to (7), wherein the circulation top has grooves on its outer surface, and the grooves are filled with the adhesive or curable resin.
(9) The counterbore according to (7) or (8), wherein the counterbored hole has a fixing groove on an inner side surface, and the fixing groove is filled with the adhesive or the curable resin. 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 method of manufacturing a ball screw nut and the ball screw of the present invention, the nut is provided with a through hole and a counterbored hole that penetrate in the radial direction at the position where the ball return passage of the nut is provided. The circulating top is brought into contact with a positioning jig placed on the surface, and the circulating top inserted into the through hole is positioned with respect to the nut. It is manufactured by removing the positioning jig from the nut after fixing it to the nut. Therefore, the boundary between the thread groove of the nut and the ball return passage of the circulating top can be formed without a step, and the vibration generated when the balls pass through the boundary between the nut and the circulating top can be eliminated. and noise can be suppressed.

1 is a perspective view of a ball screw according to a first embodiment of the invention; FIG. 1. It is explanatory drawing which shows the manufacturing procedure of the ball screw of FIG. FIG. 8 is a perspective view of a nut of the ball screw of the second embodiment; (a) is a perspective view of the nut of the ball screw of the first modification, (b) is a perspective view of the nut of the ball screw of the second modification. (a) is a perspective view of a ball screw nut of a third modification, and (b) is a perspective view of a ball screw nut of a fourth modification.

Hereinafter, a method for manufacturing a ball screw nut 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 transportation and precision positioning of machine tools, industrial machines, and the like. It is suitably used for high-precision machine tools used for

The ball screw 1 includes a screw shaft 10 , a nut 20 , a plurality of balls 30 and a plurality of circulating elements 40 . The screw shaft 10 is formed in a cylindrical shape centering 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, the inner diameter of which is larger than the outer diameter of the screw shaft 10, and the nut 20 is fitted on the screw shaft 10 with a predetermined gap. One end of the nut 20 is provided with a flange 25 for coupling with an object to be guided. A second thread groove 21 having a lead equal to that of the first thread groove 11 of the screw shaft 10 and facing the first thread groove 11 is formed on the inner peripheral surface of the nut 20 . The first thread groove 11 of the screw shaft 10 and the second thread groove 21 of the nut 20 form a rolling path (not shown) having a substantially circular cross section. A plurality of balls 30 are filled and arranged in this rolling path so as to be able to roll.

A plurality of circulating elements 40 are mounted on the inner peripheral surface of the nut 20 to return the balls 30 to the front rolling path. Each circulation top 40 is formed in a substantially columnar shape so that the maximum outer diameter corresponds to the inner diameter of a circular through-hole 23 to be described later. A substantially S-shaped ball return passage 42 is formed on the inner surface of each circulating element 40 to connect one end of the rolling path and the other end of the rolling path one roll before. The ball return passage 42 scoops up the balls 30 rolling along the rolling path toward each circulating top 40 in the radial direction of the screw shaft 10, and further, causes them to climb over the screw thread 12 of the screw shaft 10 and reach the position before one turn ( The ball 30 can be circulated by returning it to the rolling path (one lead before).

A substantially annular endless circulation path (not shown) is formed outside the screw shaft 10 by the ball return path 42 and the rolling path. Accordingly, as the screw shaft 10 rotates relative to the nut 20, the plurality of balls 30 endlessly circulate in the endless circulation path, so that the nut 20 and the screw shaft 10 are axially aligned with each other. linear motion is possible.

Next, a method of manufacturing the nut 20 having the second thread groove 21 and the ball return passage 42 will be described with reference to FIG. In the method of manufacturing the nut 20 of the present embodiment, the circulating top 40 having the ball return passage 42 formed therein is positioned on the nut 20 using the positioning jig 50 , and then the circulating top 40 is bonded to the nut 20 with an adhesive or a hardening resin 61 . 20 and installed on the nut 20 so that the boundary between the second screw groove 21 and the ball return passage 42 is connected without a step.

First, the positioning jig 50 is inserted inside the nut 20, as shown in FIG. 2(a). In the nut 20, as described above, the second thread groove 21 is formed in the inner peripheral surface of the nut 20 having the flange 25, and the through hole 23 that penetrates in the radial direction at the position where the ball return passage 42 is formed. and a counterbore 24 formed on the outer diameter side of the through hole 23 . In the embodiment shown in FIG. 2( a ), the through hole 23 is a round hole, and the counterbore 24 has a facing surface with a width equal to or larger than the outer diameter of the through hole 23 , and has an oval shape larger than the through hole 23 . is a hole.

The positioning jig 50 includes a semi-cylindrical positioning portion 51 for positioning the ball return passage 42 of the circulation top 40 with respect to the second thread groove 21 of the nut 20, and the positioning portion 51 for operating the positioning jig 50. It is formed in the shape of a shaft with a gripping portion 54 extending from it.

The positioning portion 51 includes a screw groove fitting portion 52 having a shape that copies the shape of the second screw groove 21 and a ball return passage fitting portion that has a shape copying the shape of the ball return passage 42 of the circulation top 40 . A portion 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 part 51 of the positioning jig 50 is formed corresponding to the shape of the inner peripheral surface around the through hole 23 and is smaller than the inner diameter of the second thread groove 21 of the nut 20 . Thereby, the positioning part 51 can move in the axial direction and the radial direction on the inner diameter side of the second thread 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, and may be smaller than a semi-cylindrical shape, or may be a cylindrical shape. may be

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

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

In this manner, the thread groove fitting portion 52 and the ball return passage fitting portion 53 of the positioning jig 50 are closely fitted to the second thread groove 21 of the nut 20 and the ball return passage 42 of the circulation top 40, respectively. Thus, the boundary between the second screw groove 21 of the nut 20 and the ball return passage 42 of the circulation top 40 is smoothly connected without a step. At this time, the recessed groove 43 of the circulation top 40 protrudes from the through hole 23 into the counterbore 24 .

Next, as shown in FIG. 2(b), an adhesive or hardening resin 61 prepared in advance in a container 60 is poured into the counterbore 24 and hardened. After the adhesive or curable resin 61 has sufficiently hardened, the positioning jig 50 is removed from the nut 20, so that the boundary between the second screw groove 21 and the ball return passage 42 can be smoothly connected without a step. A nut 20 is fabricated having a smoothed rolling path.

Since the adhesive or curable resin 61 is also filled in the recessed groove 43 of the circulating element 40 and cured, the circulating element 40 can be strongly fixed to the nut 20 not only by adhesive force but also mechanically. . As a result, the circulating top 40 can be reliably fixed to the nut 20 even if it is not made of synthetic resin, but is also made of metal, or is made of polyacetal, which is difficult to adhere. .

As the curable resin 61, it is preferable to use an epoxy resin or a two-liquid epoxy resin from the viewpoint of strength and moldability.

As described above, according to the method of manufacturing a ball screw nut and the ball screw of the present embodiment, the nut 20 has the through hole 23 and the through hole 23 that penetrate in the radial direction at the position where the ball return passage 42 of the nut 20 is provided. A counterbore hole 24 is formed, and the circulation top 40 is brought into contact with a positioning jig 50 arranged on the inner peripheral surface of the nut 20 to position the circulation top 40 inserted into the through hole 23 with respect to the nut 20. The positioning jig 50 is removed from the nut 20 after the circulating top 40 is fixed to the nut 20 by pouring an adhesive or a curable resin 61 into the hole 24 and hardening it. Therefore, the boundary between the screw groove 21 of the nut 20 and the ball return passage 42 of the circulating top 40 can be smoothly connected without a step, so that the balls 30 move along 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 a part.

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

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

Further, the circulating top 40 has a groove 43 on its outer surface, and the groove 43 is filled with an adhesive or a hardening resin 61 , so that the circulating top 40 can be firmly fixed to the nut 20 .

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

(Second embodiment)
Next, a method for manufacturing a ball screw nut 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 counterbored hole 24 . Other parts, including the positioning jig 50, are the same as in the first embodiment, so descriptions thereof will be omitted.

In the second embodiment, a pair of fixing grooves 26 (only one of which is shown in the figure) are formed along the longitudinal direction on opposite flat side surfaces of the counterbored hole 24 . Also in the manufacturing method of the present embodiment, the adhesive or curable resin 61 is poured into the countersunk holes 24 around the circulation top 40 with the grooves 43 protruding from the through holes 23 and cured. Since the adhesive or curable resin 61 is filled in the recessed groove 43 of the circulation element 40 and the fixed groove 26 of the counterbore 24 and hardens, the circulation element 40 is more strongly fixed to the nut 20 and the through hole is closed. 23 can be prevented.
Other configurations and actions are the same as those of the first embodiment.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate.
For example, in the above embodiment, the counterbore 24 is oval, but as in the modification shown in FIG. may Further, as in the modification shown in FIG. 4(b), even in the case of a circular counterbore 24A, a pair of fixing grooves 26 (see FIG. only one side is shown) may be formed.

Further, in the above embodiment, the through hole 23 is circular and the counterbore 24 is oval. However, as in the modification shown in FIG. It may be an oblong hole having a long axis that is inclined, in other words, in the axial direction of the ball return passage 42, and the counterbored hole 24A may be circular. Also in this case, a pair of fixing grooves 26 may be formed on the side surface of the counterbored hole 24A as in the modification shown in FIG. 5(b).

1 ball screw 10 screw shaft 11 first screw groove (screw groove)
20 nut (ball screw nut)
21 Second thread groove (thread groove)
23, 23A through holes 24, 24A counterbore 30 ball 40 circulation top 42 ball return passage 43 concave groove 50 positioning jig 52 screw groove fitting portion 53 ball return passage fitting portion 61 hardening resin

Claims (8)

A method for manufacturing a ball screw nut, wherein a circulating top having a ball return passage connected to the thread groove is installed in the nut having a spiral thread groove formed on the inner peripheral surface, the method comprising:
a step of preparing the nut having a radially penetrating through-hole formed at a position where the ball return passage is provided, and a counterbore formed on the outer diameter side of the through-hole;
arranging a positioning jig on the inner peripheral surface of the nut where the through hole opens;
a step of bringing the circulating top into contact 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 recessed grooves formed in the counterbore and the outer surface of the circulating top and curing the resin to fix the circulating top to the nut;
removing the positioning jig from the nut;
A method for manufacturing a ball screw nut, comprising: The positioning jig is arranged on the inner peripheral surface of the nut by fitting a thread groove fitting portion having a shape of the thread groove of the nut copied into the thread groove. 2. The method for manufacturing the ball screw nut according to 1. The circulating top is positioned by fitting the ball return passage into a ball return passage fitting portion formed in the positioning jig and having the shape of the ball return passage copied. The method for manufacturing a ball screw nut according to claim 1 or 2, characterized in that: 4. The counterbored hole according to any one of claims 1 to 3 , characterized in that a fixing groove is provided on an inner side surface of the counterbore, and the fixing groove is filled with the adhesive or curable resin. manufacturing method of ball screw nut. The method for manufacturing a ball screw nut according to any one of claims 1 to 4 , wherein the curable resin is an epoxy resin or a two-liquid epoxy resin. a screw shaft having a helical thread groove formed on its outer peripheral surface;
a nut arranged around the screw shaft and having a helical 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 attached to the nut and having a ball return passage for circulating from one end to the other end of the rolling path and a concave groove formed on the outer surface ;
A ball screw comprising
The nut has a radially penetrating through-hole in which the circulating element is arranged, and a counterbored hole formed on the outer diameter side of the through-hole,
A ball screw according to claim 1, wherein the circulating link is fixed to the nut by an adhesive or a curable resin in the recessed groove of the countersunk hole and the circulating link. 7. The ball screw according to claim 6 , wherein the counterbored hole has a fixing groove on an inner side surface, and the fixing groove is filled with the adhesive or the curable resin. 8. The ball screw according to claim 6 , wherein the curable resin is an epoxy resin or a two-liquid epoxy resin.

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