JP6459574B2 - Circulating top and ball screw provided with the same - Google Patents

Description

  The present invention relates to a circulating screw for a ball screw and a ball screw provided with the same.

2. Description of the Related Art Conventionally, an internal circulation type ball screw having a screw shaft, a nut, and a rolling element (for example, a ball) and provided with a circulation top for circulating a plurality of rolling elements interposed between the screw shaft and the nut. It has been known.
The technique described in Patent Document 1 is an example of this type of ball screw, and adopts a shape in which the return path of the circulating top is made into a tunnel shape and the rolling element is not brought into contact with the land portion of the screw shaft. According to the circulation top having such a structure, as a ball screw provided with a circulation top, compared to the conventional internal circulation structure in which the rolling element is circulated so as to cross over the land portion of the screw shaft to the adjacent spiral groove. It is said that the operability of can be improved.

The technique described in Patent Document 1 has a function of fixing the circulating top to the nut by a cylindrical cross-sectional element extending from the wall of the circulating top. By making such a configuration, the circulation top is fixed by restricting the outer diameter direction, the axial direction, and the rotation direction of the nut.
However, as in the technique disclosed in Patent Document 1, when the ball circulation path is made into a tunnel shape, the arms extending along the ball groove from both walls of the circulation top are simply moved along the ball groove from the inside of the nut. When the ball circulates, the component force in the direction of gravity is transmitted from the ball to the circulation top and is more likely to be pressed against the screw shaft, which may cause malfunction or abnormal heat generation.

  Therefore, as a technology that can solve such a problem, a member that forms a circulation path of the ball together with the ball rolling path includes a metal pipe in which a tunnel-like circulation path is curved and a pipe Patent Document 2 discloses a ball screw that is configured with a resin-made covering portion that covers the outside and fits into a mounting hole provided in a nut.

Japanese Examined Patent Publication No.57-33464 JP 2003-329097 A

However, even with the technique disclosed in Patent Document 2, the resin covering portion that covers the pipe is fitted into the nut mounting hole to fix the pipe to the nut. There was room for improvement in suppression of decline, malfunction and abnormal heat generation.
Accordingly, the present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide a circulating top capable of improving workability and suppressing malfunction and abnormal heat generation, and a ball screw provided with the same. is there.

A mode with a circulating top for achieving the above object includes a screw shaft having a spiral groove on the outer peripheral surface, and a nut having a spiral groove on the inner peripheral surface that is externally fitted to the screw shaft; A cylindrical return path used for a ball screw having a plurality of rolling elements arranged in a track formed by these spiral grooves, mounted on the nut, and for returning the rolling element to a previous track. With
A circulation top main body composed of two divided bodies each formed with a return groove for forming the return path and formed with a joining surface so as to be orthogonal to the return path, and the ball screw from both side surfaces of the divided body, respectively. An engaging portion provided so as to project along the spiral groove and limit the movement of the circulating top body;
A fixing hole in which a fixing member provided in a through hole exposing the engaging portion formed in the nut is fitted or screwed is provided in the engaging portion.

Here, in the circulating top, the circulating top body is composed of two divided bodies each formed with a return groove that forms the return path, and a joining surface is formed so as to be orthogonal to the return path. Engagement portions may be provided so as to project from the both side surfaces of the divided body along the spiral groove of the ball screw so as to limit the movement of the circulating top body.
In another aspect of the ball screw for achieving the above object, a screw shaft having a spiral spiral groove on the outer peripheral surface, and a nut having a spiral spiral groove on the inner peripheral surface by being externally fitted to the screw shaft And a plurality of rolling elements arranged in a track formed by these spiral grooves, and a circulating top having a cylindrical return path that is attached to the nut and returns the rolling element to the previous track. Prepared,
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top, and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole that exposes the engagement portion, and a fixing member that fixes the circulation top by urging the engagement portion is configured as described above. It is provided in the through hole.

In another aspect of the ball screw for achieving the above object, a screw shaft having a spiral groove on the outer peripheral surface, and a spiral groove on the inner peripheral surface that is externally fitted to the screw shaft. A circulating top having a nut, a plurality of rolling elements arranged in a raceway formed by these spiral grooves, and a cylindrical return path that is attached to the nut and returns the rolling body to a previous raceway With
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top, and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole exposing the engagement portion,
A fixing member provided in the through hole is fitted or screwed into the engaging portion.

In another aspect of the ball screw for achieving the above object, a screw shaft having a spiral groove on the outer peripheral surface, and a spiral groove on the inner peripheral surface that is externally fitted to the screw shaft. A circulating top having a nut, a plurality of rolling elements arranged in a raceway formed by these spiral grooves, and a cylindrical return path that is attached to the nut and returns the rolling body to a previous raceway With
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top, and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole exposing the engagement portion,
A fixing hole into which the fixing member provided in the through hole is fitted or screwed is provided in the engaging portion.

Here, in the ball screw, the fixing member may have a locking portion locked in the fixing hole.
In the ball screw, the main body of the circulating top is composed of two divided bodies each having a return groove that forms the return path and a joining surface that is orthogonal to the return path. A joint portion may be provided so as to protrude from the both side surfaces of the divided body along the spiral groove of the ball screw to limit the movement of the circulating top body.

  ADVANTAGE OF THE INVENTION According to this invention, workability | operativity improves and the ball screw provided with the circulating top which can suppress a malfunction and abnormal heat generation, and this can be provided.

It is a perspective view which shows the structure in one Embodiment of a ball screw. It is sectional drawing of the nut in one Embodiment of a ball screw. It is a figure which shows the structure in one Embodiment of a circulation top, (a) is a perspective view which shows the structure of the division body which comprises a circulation top, (b) is a top view which shows the structure of a division body. It is a figure which shows the aspect with which it mounts | wears with a nut in one Embodiment of a circulation top, (a) is a side view, (b) is a front view from an axial direction. (A)-(c) is a front view from the axial direction which shows the aspect with which the nut in other embodiment of a circulation top is mounted | worn.

Hereinafter, an embodiment of a circulating top and a ball screw including the same will be described with reference to the drawings.
FIG. 1 is a perspective view showing a configuration of an internal circulation type ball screw according to the present embodiment. In FIG. 1, the nut 20 is shown cut along a plane including its axis. FIG. 2 is a cross-sectional view of a nut in the ball screw of this embodiment. In addition, in FIG. 2, the installation position of the circulating top is also shown in the sectional view of the nut. FIG. 3 is a diagram showing the configuration of the circulating top of the present embodiment, (a) is a perspective view showing the configuration of the divided body constituting the circulating top, and (b) is a plan view showing the configuration of the divided body. It is. Note that FIG. 3A shows only one of the two divided bodies (first divided body). Moreover, FIG. 4 is a figure which shows the aspect attached to a nut in one Embodiment of a circulation top, (a) is a side view, (b) is a front view from an axial direction. In addition, in Fig.4 (a), sectional drawing of a nut is also attached for understanding of description.

(Ball screw)
As shown in FIG. 1, the ball screw 1 includes a screw shaft 10, a nut 20, and rolling elements (for example, balls) 30.
The screw shaft 10 has a spiral groove 11 having a predetermined lead formed on the outer peripheral surface 10a 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.

  The nut 20 has a flange 22 for coupling with a guide object at one end thereof. A helical spiral groove 21 having a lead equal to the lead of the screw shaft 10 is formed on the inner peripheral surface 20 a of the nut 20. The spiral groove 11 and the spiral groove 21 facing the screw shaft 10 and the nut 20 form a substantially circular cross section. A plurality of rolling elements 30 are filled in the track.

  As shown in FIG. 2, the nut 20 is formed with a circulation top insertion hole 23 for attaching the circulation top 100. The circulation top insertion hole 23 is a long hole penetrating from the outer periphery to the inner periphery of the nut 20. The long hole is processed by, for example, an end mill, and is formed by inclining the end mill by a predetermined angle with respect to a line orthogonal to the center line of the nut 20. This predetermined angle is set to an angle at which the rolling element 30 that rolls in the spiral groove 11 does not change direction suddenly by a cylindrical return path (also referred to as a ball return path) 111 formed in the circulation top 100. . A plurality (for example, three) of the circulating top insertion holes 23 are machined according to the number of the circulating tops 100 at equal intervals in the circumferential direction of the nut 20.

<Through hole>
Furthermore, as shown in FIG. 4, there are a plurality of through holes 24 around the circulation top insertion hole 23 of the nut 20 that expose an engaging portion 120 described later when the circulation top 100 is attached to the circulation top insertion hole 23. Is formed. Two or more through holes 24 are provided so as to form a diagonal with respect to the circulation top insertion hole 23. These through holes 24 are provided with a fixing member 200 that urges the engaging portion 120 of the circulation top 100 mounted in the circulation top insertion hole 23 and consequently fixes the circulation top 100. In addition, if the fixing member 200 is provided in the through-hole 24 in order to fix the circulation top 100, the installation aspect is not limited.

(Circulation top)
Next, the above circulating top 100 will be described in more detail.
The circulating top 100 is formed from, for example, a sintered alloy. As shown in FIG. 2, the circulating top 100 includes a circulating top main body 110 in which a return path 111 is formed, and two engagements provided so as to protrude from opposite sides of the circulating top main body 110 in the longitudinal direction. Parts 120 and 120.
One circulating top 100 is provided for one turn of the ball row filled in the ball screw 1. That is, since the number of turns of the rolling element 30 is determined from the load applied to the ball screw 1, the number of the circulating tops 100 is appropriately determined (for example, 3) depending on the load applied to the ball screw 1.

<Circulation top body>
As shown in FIG. 2, the circulating top main body 110 is mounted in each circulating top insertion hole 23 of the nut 20. That is, the outer shape of the circulating top body 110 is formed in alignment with the circulating top insertion hole 23 of the nut 20 described above. The circulating top main body 110 is provided with a step portion (not shown) around the circulating top main body 110 so that the circulating top main body 110 does not fall off to the outer peripheral surface side when being mounted from the inner peripheral surface 20a of the nut 20.

  A cylindrical return path 111 that connects one end of the track and the other end of the track just before the winding is formed inside the circulation top body 110. The return path 111 extends in a substantially S shape in the longitudinal direction of the circulation top main body 110 and is formed to open toward the inner peripheral side of the nut 20. This substantially S-shape is a shape determined from a function for returning the rolling elements 30. That is, the return path 111 needs to change the course of the rolling element 30 so as to return the rolling element 30 rolling on the track to the track one turn before and align with the track. Therefore, when the planar shape is a cam curve, for example, a cam curve corresponding to a modified sine curve is combined to form a substantially S-shape so as to suppress rapid fluctuations in acceleration relative to the lift. Has been.

Further, a tongue (not shown) for guiding the rolling element 30 into the return path 111 is provided in the vicinity of at least one opening of the return path 111 of the circulation top 100.
The return path 111 has a cross section in the short direction of the circulating top main body 110 from the tongues provided at both ends in the longitudinal direction of the circulating top 100 toward the center in the longitudinal direction of the circulating top main body 110. It has a continuous U shape with an inner diameter that matches the outer diameter of this, and forms a cylindrical (tunnel) shape integrally with the aforementioned substantially S shape.

<Engagement part>
When the circulating top 100 is mounted in the circulating top insertion hole 23 of the nut 20, the engaging portions 120 are provided so that the respective engaging portions 120, 120 protrude along the spiral groove 11.
Further, as shown in FIGS. 4A and 4B, the engaging portion 120 is urged by the fixing members 200 respectively provided in the plurality of through holes 24 of the nut 20. It is sandwiched and fixed between the fixing member 200 and the spiral grooves 11 and 11. Note that the circulating top 100 is fixed by the fixing member 200 (biased to the engaging portion 120) with an urging force that does not hinder the rotation of the screw shaft 10.

Since the engaging portions 120 and 120 extend in opposite directions to engage with the adjacent spiral grooves 11 and 11 and are also biased by the fixing member 200, the circulating top 10 is properly fixed. There is an effect.
As described above, the return path 111 (and the tongue portion) is provided in the circulation top 100, so that the rolling elements 30 rolling in the track toward the circulation top 100 are efficiently scooped in the radial direction of the screw shaft 10. The rolling element 30 can be circulated by lifting it, getting over the thread, and returning it to the track just before one winding (one lead before). Then, a substantially circular infinite circulation path is formed outside the screw shaft 10 by the path formed by the return path 111 and the track. As a result, the rolling element 30 rolls between the spiral groove 11 and the spiral groove 21 in accordance with the relative rotation of the screw shaft 10 with respect to the nut 20, so that the nut 20 rotates relative to the screw shaft 10. 10 linear movements are possible.

[Split]
Here, as shown in FIGS. 3 (a) and 3 (b), the circulating top body 110 has two joint surfaces 101A and 101B formed so as to be orthogonal to the return path 111 formed in the circulating top 100. It is good also as an aspect which consists of division body 110A, 110B. Specifically, the above-described two engaging portions 120 and 120 may be provided as two engaging portions 120A and 120B provided so as to protrude in opposite directions from both side surfaces of the divided bodies 110A and 110B.
In the return path 111 described above, each return groove (only one return groove 111A, see FIG. 4 (a)) formed on the joint surface side of each of the divided bodies 111A and 111B is the same as that of the divided bodies 111A and 111B. Formed by superposition.

(Other embodiments)
Fig.5 (a)-(c) is a front view from the axial direction which shows the aspect attached to the nut in other embodiment of a circulation top. 5B and 5C, the nut and the spiral groove of the screw shaft are omitted.
As another embodiment of the circulation top 100 and a ball screw provided with the same, as shown in FIGS. 5A and 5B, the engagement portions 120 and 120 of the circulation top 100 are provided in the through holes 24, respectively. The circulating top 100 may be fixed to the nut 20 by fitting or screwing the fixed member 202 (200). For example, when a nail-shaped member is employed as the fixing member 202, the fixing member 202 made of a hard material having a higher hardness than the engaging portion 120 is fitted into the engaging portions 120, 120 made of a soft material. The circulating top 100 is fixed to the nut 20. On the other hand, when a male screw (wood screw) is used as the fixing member 202, the fixing member 202 made of a hard material having a hardness higher than that of the engaging portion 120 is screwed into the engaging portions 120, 120 made of a soft material and circulated. 100 is fixed to the nut 20.

By setting it as such a structure, the fixation operation | work to the nut 20 of the circulation top 100 can be performed simply and reliably.
Further, as another embodiment of the circulating top 100 and the ball screw provided with the same, as shown in FIG. 5C, the engaging portions 120, 120 of the circulating top 100 are provided in the through holes 24, respectively. Fixing holes 121, 121 into which the fixing member 201 is fitted may be provided, and the fixing member 203 (200) may have a “prevention” locking portion 203 a that is locked to the fixing hole 121. The fixing member 203 is, for example, a pin, and the locking portion 203a is a so-called “barb”. The head of the pin may be integrated, or may be combined by providing a fastening structure such as a triangular screw on the head of the pin as a separate body.

Even with this configuration, the circulating top 100 can be easily and reliably fixed to the nut 20.
As described above, according to the circulating top of this embodiment and the ball screw provided with the circulating top, the through hole for fixing the circulating top to the nut by bringing the fixing member into contact with the engaging portion of the circulating top is provided in the nut. Since it is provided, it is possible to provide a circulating top that can reduce the number of components and suppress malfunction and abnormal heat generation, and a ball screw including the same.
In addition, the circulation top and ball screw which concern on this invention are not limited to the said embodiment, A various deformation | transformation is possible unless it deviates from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Ball screw 10 Screw shaft 11 Spiral groove 20 Nut 21 Spiral groove 23 Circulation top insertion hole 24 Through-hole 30 Rolling element (ball)
DESCRIPTION OF SYMBOLS 100 Circulation top 100A 1st division body 100B 2nd division body 110 Circulation top main body 111 Return path 120 Engagement part 121 Fixing hole 200 Fixing member

Claims (7)

A screw shaft having a spiral spiral groove on the outer peripheral surface, a nut having a spiral spiral groove on the inner peripheral surface and fitted on the screw shaft, and a track formed by these spiral grooves are disposed. Used in a ball screw including a plurality of rolling elements, mounted on the nut, and provided with a cylindrical return path for returning the rolling elements to a previous track,
A circulation top main body composed of two divided bodies each formed with a return groove for forming the return path and formed with a joining surface orthogonal to the return path, and a ball screw of each of the ball screws from both side surfaces of the divided body. An engaging portion that protrudes along the spiral groove and is provided to limit the movement of the circulating top body;
A circulating top, wherein a fixing hole in which a fixing member provided in a through hole exposing the engaging portion formed in the nut is fitted or screwed is provided in the engaging portion.   The circulating top main body includes two divided bodies each having a return groove that forms the return path, and a joining surface formed so as to be orthogonal to the return path, and the engaging portion is formed of the divided body. The circulating top according to claim 1, wherein the circulating top is provided so as to protrude from both side surfaces along the spiral groove of the ball screw to limit the movement of the circulating top body. A screw shaft having a spiral spiral groove on the outer peripheral surface, a nut having a spiral spiral groove on the inner peripheral surface and fitted on the screw shaft, and a track formed by these spiral grooves are disposed. A plurality of rolling elements, and a circulating top having a cylindrical return path that is attached to the nut and returns the rolling elements to a previous track,
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole exposing the engagement portion, and a fixing member for fixing the circulation top by urging the engagement portion is the A ball screw provided in the through hole. A screw shaft having a spiral spiral groove on the outer peripheral surface, a nut having a spiral spiral groove on the inner peripheral surface and fitted on the screw shaft, and a track formed by these spiral grooves are disposed. A plurality of rolling elements, and a circulating top having a cylindrical return path that is attached to the nut and returns the rolling elements to a previous track,
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole for exposing the engagement portion,
A ball screw, wherein a fixing member provided in the through hole is fitted or screwed into the engaging portion. A screw shaft having a spiral spiral groove on the outer peripheral surface, a nut having a spiral spiral groove on the inner peripheral surface and fitted on the screw shaft, and a track formed by these spiral grooves are disposed. A plurality of rolling elements, and a circulating top having a cylindrical return path that is attached to the nut and returns the rolling elements to a previous track,
The circulation top is provided so as to restrict the movement of the circulation top body by projecting along the spiral groove of the ball screw from both sides of the circulation top and the circulation top body formed with the return path. An engaging portion,
The nut is formed with a circulation top insertion hole for mounting the circulation top and a through hole for exposing the engagement portion,
A ball screw, wherein a fixing hole into which a fixing member provided in the through hole is fitted or screwed is provided in the engaging portion.   The ball screw according to claim 5, wherein the fixing member has a locking portion that is locked to the fixing hole.   The circulating top main body includes two divided bodies each having a return groove that forms the return path, and a joining surface formed so as to be orthogonal to the return path, and the engaging portion is formed of the divided body. The ball screw according to any one of claims 3 to 6, wherein the ball screw is provided so as to protrude from both side surfaces along the spiral groove of the ball screw and to limit the movement of the circulating top body.

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