JP7687239B2 - Ball screw device - Google Patents

Description

The present invention relates to a ball screw device.

A ball screw device is a device that converts rotational motion into linear motion with high efficiency by inserting balls into screw grooves on the screw shaft and nut, and rotating and revolving the balls when the screw shaft or nut rotates.

This ball screw device is designed so that the balls circulate within the rolling path so that the screw shaft or nut continues to convert rotational motion into linear motion, and there are various circulation methods for circulating the balls, such as the tube type, top type, or end cap type.

However, ball screw devices used as precision feed mechanisms in machine tools, injection molding machines, semiconductor device manufacturing equipment, etc., are at risk of thermal deformation of the screw shaft and nut when exposed to high temperatures. Such thermal deformation can lead to abnormal load distribution on the balls and deterioration of operability, affecting the positioning accuracy of the feed mechanism, and so are used in a cooled state.

Patent Document 1 describes how a cooling fluid passage is formed in the nut that constitutes the ball screw device, and cooling fluid is supplied from a cooling fluid source and circulated into this cooling fluid passage to directly cool the nut, thereby reducing thermal deformation caused by heat generation in the ball screw device.

Patent Document 2 also describes cooling the ball screw device by placing a cooling pipe in a grinding relief groove formed in the spiral groove of the nut.

JP 2000-24876 A Patent No. 5644668

In the ball screw device described in Patent Document 1, cooling fluid passages for circulating cooling fluid through the nut are formed in the axial direction. For this reason, particularly in nuts with large axial dimensions, it is necessary to form elongated cooling fluid passages, which increases processing costs. In addition, because there is a distance between the cooling fluid passages and the rolling path, which is the heat source, there is a risk of insufficient cooling in environments where high temperatures are likely to occur or under severe operating conditions.

In addition, in the ball screw device described in Patent Document 2, the cooling pipe is placed in the grinding relief groove, so the outer diameter dimension of the cooling pipe that can be placed is limited to the size of the grinding relief groove. If the maximum width dimension of the grinding relief groove in this ball screw device is 1/4 or more of the diameter of the ball used, the contact area between the ball and the screw groove will be small and the screw groove shape will not work. For this reason, for example, the cooling pipe is limited to the width dimension of the grinding relief groove, which is at most 1/4 or less of the diameter of the ball, making efficient cooling difficult. Moreover, in recent years, there has been an increase in ball screw devices that do not have a grinding relief portion due to cutting finishing, and it may not be possible to secure space to accommodate the cooling pipe.

The present invention aims to provide a ball screw device that can maintain high precision by providing balanced and efficient cooling while keeping costs down.

The present invention comprises the following configurations.
(1) A screw shaft having a helical screw groove on an outer circumferential surface thereof;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
The screw shaft and the nut have mutually opposing spiral grooves formed in the land portions between the rolling paths,
A cooling pipe is disposed in the spiral groove of the screw shaft or the nut.
Ball screw device.
(2) a screw shaft having a helical screw groove on an outer circumferential surface;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
A spiral groove is formed in a land portion between the rolling paths in the screw shaft or the nut,
A cooling pipe is disposed in the spiral groove.
Ball screw device.

The present invention provides a ball screw device that can maintain high precision by providing balanced and efficient cooling while keeping costs down.

1 is a cross-sectional view taken along an axial direction of a ball screw device according to a first embodiment. 2 is a cross-sectional view taken along the axial direction at a boundary portion between a screw shaft and a nut of the ball screw device according to the first embodiment. FIG. 2 is a cross-sectional view taken along the axial direction of a nut constituting the ball screw device according to the first embodiment. FIG. 11 is a cross-sectional view taken along the axial direction at a boundary portion between a screw shaft and a nut of a ball screw device according to a second embodiment. FIG. FIG. 11 is a cross-sectional view taken along the axial direction of a ball screw device according to a third embodiment. 13A and 13B are a front view and a side view seen from one end side of a screw shaft constituting a ball screw device according to a third embodiment. FIG. 11 is a side view, partially in cross section, showing the end structure of the screw shaft of a ball screw device according to a third embodiment. FIG. 13 is a cross-sectional view taken along the axial direction at a boundary portion between a screw shaft and a nut of a ball screw device according to a fourth embodiment. FIG. 13 is a cross-sectional view taken along the axial direction at the boundary between the screw shaft and the nut, showing another example of a ball screw device according to the fourth embodiment. FIG. 13 is a cross-sectional view taken along the axial direction at a boundary portion between a screw shaft and a nut of a ball screw device according to a fifth embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
First Embodiment
First, a ball screw device according to a first embodiment will be described.
FIG. 1 is a cross-sectional view along the axial direction of a ball screw device 100 according to a first embodiment.
1, a ball screw device 100 according to the first embodiment is configured to include a screw shaft 10, a nut 20, and a plurality of balls 30. The screw shaft 10 is formed to have a circular cross section centered on the central axis, and a first helical screw groove (thread groove) 11 is formed on the outer circumferential surface thereof.

The nut 20 is generally cylindrical, with an inner diameter larger than the outer diameter of the screw shaft 10, and is fitted onto the screw shaft 10 with a specified gap. One end of the nut 20 is provided with a flange 25 for coupling with a guide object.

A second screw groove (thread groove) 21 is formed on the inner peripheral surface of the nut 20, which has the same lead as the first screw groove 11 of the screw shaft 10 and faces the first screw groove 11. The first screw groove 11 of the screw shaft 10 and the second screw groove 21 of the nut 20 form a rolling path 32 with a substantially circular cross section. A plurality of balls 30 are packed and arranged in the rolling path 32 so that they can roll.

The ball screw device 100 is structured so that the balls 30 circulate within the rolling path 32 so that the screw shaft 10 or the nut 20 can continue to convert rotational motion into linear motion. As a result, multiple balls 30 circulate infinitely as the screw shaft 10 rotates relative to the nut 20, allowing the screw shaft 10 and the nut 20 to perform relative linear motion in the axial direction. The circulation method for circulating the balls 30 may be any of the tube type, top type, and end cap type.

FIG. 2 is a cross-sectional view along the axial direction of a boundary portion between the screw shaft 10 and the nut 20 of the ball screw device 100 according to the first embodiment.
As shown in FIG. 2, the screw shaft 10 has a first land portion (land portion) 12 between the first screw grooves 11 that form the rolling path 32, and similarly, the nut 20 has a second land portion (land portion) 22 between the second screw grooves 21 that form the rolling path 32.

The screw shaft 10 has a first helical groove (helical groove) 13 formed in the first land portion 12 between the rolling paths 32, and the nut 20 has a second helical groove (helical groove) 23 formed in the second land portion 22 between the rolling paths 32. The first helical groove 13 and the second helical groove 23 formed in the screw shaft 10 and the nut 20 are formed in positions facing each other.

The first spiral groove 13 and the second spiral groove 23 have the same pitch P1 as the pitch P1 of the rolling path 32 consisting of the first screw groove 11 and the second screw groove 21. In addition, the first spiral groove 13 and the second spiral groove 23 are formed at the center positions of the first land portion 12 and the second land portion 22, so that the dimension between the rolling paths 32 on both sides is the same dimension A.

The groove shapes of the first spiral groove 13 and the second spiral groove 23 may be arc-shaped like the first screw groove 11 and the second screw groove 21, but may also be shapes other than arc-shaped, such as rectangular or trapezoidal. In this example, the first spiral groove 13 and the second spiral groove 23 have a smaller arc-shaped groove shape than the first screw groove 11 and the second screw groove 21.

The nut 20 is provided with a cooling pipe 40. A refrigerant such as cooling water is passed through the cooling pipe 40. The cooling pipe 40 is disposed in the second spiral groove 23 of the nut 20 and is formed in a spiral shape along the second spiral groove 23. The cooling pipe 40 may be, for example, a copper pipe, a stainless steel pipe, a polyurethane tube, or a nylon tube. The cooling pipe 40 is fitted into the second spiral groove 23 and fixed to the nut 20. The cooling pipe 40 may also be fixed to the second spiral groove 23 with an adhesive.

The cooling pipe 40 provided in this nut 20 has an outer diameter that does not come into contact with the screw shaft 10 facing the fixed side when fixed to the second spiral groove 23. As a result, the cooling pipe 40 is positioned with a gap between it and the screw shaft 10.

FIG. 3 is a cross-sectional view taken along the axial direction of the nut 20 that constitutes the ball screw device 100 according to the first embodiment.
As shown in Fig. 3, the nut 20 has an L-shaped through hole 26 formed at both ends thereof. The through hole 26 has a radial hole portion 26a extending in the radial direction and an axial hole portion 26b extending in the axial direction. The radial hole portion 26a of each of the through holes 26 communicates with the second helical groove 23, and the axial hole portion 26b opens at the end surface of the nut 20. The cooling pipe 40 disposed in the second helical groove 23 of the nut 20 is drawn out to the outside through these through holes 26. The cooling pipe 40 drawn out from the end surface of the nut 20 to the outside is connected to a cooling source (not shown) such as a cooling water circulator, and cooling water is circulated through the cooling pipe 40 by the cooling source.

In the ball screw device 100 configured as described above, cooling water is circulated through the cooling pipe 40, providing uniform cooling throughout the axial direction. This prevents abnormal load distribution and deterioration of operability of the balls 30 caused by thermal deformation of the screw shaft 10 and the nut 20.

As described above, according to the ball screw device 100 of the first embodiment, the space between the rolling paths 32, which are the heat source, is cooled by the cooling pipe 40 along the second spiral groove 23, and heat generation in the rolling paths 32 can be suppressed with high cooling efficiency, and abnormal load distribution and deterioration of operability of the balls 30 due to thermal deformation of the screw shaft 10 and nut 20 can be suppressed, and high precision can be maintained as a feed mechanism.

In addition, the second spiral groove 23 in which the cooling pipe 40 is arranged can be easily machined when forming the second screw groove 21, so costs can be reduced compared to a structure in which a long and thin cooling fluid passage hole is formed in the axial direction of the nut. Moreover, compared to a structure in which a cooling pipe is arranged in a grinding relief groove, a cooling pipe 40 with a large diameter (about four times larger) can be arranged in a spiral shape, and the cooling efficiency can be significantly improved (by more than about four times).

In addition, the cooling pipe 40 has an outer diameter that does not come into contact with the screw shaft 10 that faces the fixed side when it is fixed to the second spiral groove 23. Therefore, interference with the screw shaft 10 that faces the fixed side of the cooling pipe 40 is avoided, and the screw shaft 10 and the nut 20 can be smoothly rotated relative to each other.

Next, ball screw devices according to second to fifth embodiments will be described.
The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

Second Embodiment
FIG. 4 is a cross-sectional view along the axial direction at a boundary portion between a screw shaft 10 and a nut 20 of a ball screw device 200 according to the second embodiment.

As shown in FIG. 4, in the ball screw device 200 according to the second embodiment, the first spiral groove 13 and the second spiral groove 23 formed with the same pitch P1 as the pitch P1 of the rolling path 32 are formed in a position offset from the center position of the first land portion 12 and the second land portion 22 to one side in the axial direction of the ball screw device 200. As a result, in a cross-sectional view, the first spiral groove 13 and the second spiral groove 23 have different dimensions B between the rolling path 32 adjacent on one side and C between the rolling path 32 adjacent on the other side. Specifically, the dimension C between the rolling path 32 adjacent on the other side is larger than the dimension B between the rolling path 32 adjacent on one side. A cooling pipe 40 is arranged in the second spiral groove 23 of the first spiral groove 13 and the second spiral groove 23 formed in such an offset position.

In the ball screw device 200 according to the second embodiment, for example, when a large load is always applied to one flank of the rolling path 32, the first spiral groove 13 and the second spiral groove 23 are formed near the flank of the rolling path 32 that receives the large load, and the cooling pipe 40 is arranged, so that the heat generated in the rolling path 32 can be more efficiently suppressed.

Third Embodiment
Fig. 5 is a cross-sectional view along the axial direction of the ball screw device 300 according to the third embodiment. Fig. 6 is a front view and a side view seen from one end side of the screw shaft 10 constituting the ball screw device 300 according to the third embodiment. Fig. 7 is a side view in which a part is cross-sectionally shown showing the end structure of the screw shaft 10 of the ball screw device 300 according to the third embodiment.

As shown in FIG. 5, in the ball screw device 300 according to the third embodiment, a cooling pipe 40 is provided on the screw shaft 10. This cooling pipe 40 is fitted into the first spiral groove 13 and fixed to the screw shaft 10. The cooling pipe 40 may also be fixed to the first spiral groove 13 by an adhesive.

The cooling pipe 40 provided on this screw shaft 10 has an outer diameter that does not contact the nut 20 facing the fixed side when fixed to the first spiral groove 13. This allows the cooling pipe 40 to be positioned with a gap between it and the nut 20.

As shown in FIG. 6, the screw shaft 10 has an L-shaped through hole 16 formed at both ends thereof when viewed from the side. The through hole 16 has a radial hole portion 16a extending in the radial direction and an axial hole portion 16b formed at the axial center of the screw shaft 10 and extending in the axial direction. The radial hole portion 16a of each of the through holes 16 communicates with the first helical groove 13, and the axial hole portion 16b opens at the end face of the screw shaft 10. The cooling pipe 40 arranged in the first helical groove 13 of the screw shaft 10 is drawn out to the outside through these through holes 16.

As shown in FIG. 7, the cooling pipe 40 drawn out from the end face of the screw shaft 10 is connected to a tube 46 extending from a cooling source such as a cooling water circulator via a joint portion 45, and cooling water is circulated through the cooling pipe 40 by the cooling source. The joint portion 45 has a cylindrical body 47 connected to the end of the tube 46 and a seal member 48 provided on the side of the cylindrical body 47 opposite to the side connected to the tube 46. The seal member 48 has a seal hole 49 in its center, and the cooling pipe 40 is inserted into this seal hole 49. The cooling pipe 40 is inserted into the seal hole 49 of the seal member 48, and is connected to the joint portion 45 in a rotatable state while being sealed. This allows the supply and recovery of cooling water to the cooling pipe 40 of the rotating screw shaft 10 to be performed smoothly.

In the case of the ball screw device 300 according to the third embodiment, the space between the rolling paths 32, which are the heat source, is cooled by the cooling pipe 40 along the first spiral groove 13, and heat generation in the rolling paths 32 can be suppressed with high cooling efficiency, and abnormal load distribution and deterioration of operability of the balls 30 caused by thermal deformation of the screw shaft 10 and nut 20 can be suppressed, and high precision can be maintained as a feed mechanism.

In addition, the first spiral groove 13 in which the cooling pipe 40 is arranged can be easily machined when forming the first screw groove 11, so costs can be reduced compared to a structure in which a long and thin cooling fluid passage hole is formed in the axial direction of the nut. Moreover, compared to a structure in which a cooling pipe is arranged in a grinding relief groove, a cooling pipe 40 with a large diameter (about four times larger) can be arranged in a spiral shape, and the cooling efficiency can be significantly improved (by about four times or more).

In addition, the cooling pipe 40 has an outer diameter that does not contact the screw shaft 10 that faces the fixed side when it is fixed to the first spiral groove 13. This avoids interference with the nut 20 that faces the fixed side of the cooling pipe 40, and allows the screw shaft 10 and the nut 20 to rotate smoothly relative to each other.

Fourth Embodiment
FIG. 8 is a cross-sectional view along the axial direction at a boundary portion between a screw shaft 10 and a nut 20 of a ball screw device 400 according to a fourth embodiment.
As shown in Fig. 8, in a ball screw device 400 according to the fourth embodiment, the screw shaft 10 does not have the first spiral groove 13, the first land portion 12 is a smooth surface, and the second spiral groove 23 is formed only in the second land portion 22 of the nut 20. A cooling pipe 40 is fitted into and fixed to the second spiral groove 23 of the nut 20. The cooling pipe 40 provided in the nut 20 has an outer diameter that does not contact the screw shaft 10 facing the fixed side when fixed to the second spiral groove 23. As a result, the cooling pipe 40 is arranged with a gap between it and the first land portion 12 of the screw shaft 10.

In the ball screw device 400 according to the fourth embodiment, the second spiral groove 23 is formed only in the nut 20, which eliminates the need to machine the first spiral groove 13 into the screw shaft 10, thereby reducing manufacturing costs.

As shown in FIG. 9, it is preferable that the cooling pipe 40 placed in the second spiral groove 23 has an outer diameter that does not protrude from the inner peripheral surface of the second land portion 22 of the nut 20 in which the second spiral groove 23 is formed.

In the fourth embodiment, the second spiral groove 23 is formed only in the second land portion 22 of the nut 20, and the cooling pipe 40 is disposed in this second spiral groove 23. However, the first spiral groove 13 may be formed only in the first land portion 12 of the screw shaft 10, and the cooling pipe 40 may be disposed in this first spiral groove 13. In this case, the cooling pipe 40 fixed to the screw shaft 10 has an outer diameter that does not contact the nut 20 facing the fixed side when fixed to the first spiral groove 13, and a gap is provided between the cooling pipe 40 and the second land portion 22 of the nut 20.

In addition, even when a cooling pipe 40 is provided on the screw shaft 10 side, it is preferable that the cooling pipe 40 to be placed in the first spiral groove 13 has an outer diameter that does not protrude from the outer peripheral surface of the first land portion 12 of the screw shaft 10 in which the first spiral groove 13 is formed (see Figure 9).

Fifth Embodiment
FIG. 10 is a cross-sectional view along the axial direction at a boundary portion between a screw shaft 10 and a nut 20 of a ball screw device 500 according to a fifth embodiment.

As shown in FIG. 10, in the case of the ball screw device 500 according to the fifth embodiment, the second spiral groove 23 is formed only in the second land portion 22 of the nut 20, and the cooling pipe 40 is disposed in this second spiral groove 23. The cooling pipe 40 fixed to the nut 20 has an outer diameter that does not contact the screw shaft 10 facing the fixed side when fixed to the second spiral groove 23, and a gap is provided between the cooling pipe 40 and the first land portion 12 of the screw shaft 10.

In this ball screw device 500, the second spiral groove 23 of the nut 20 has a pitch P2 that is different from the pitch P1 of the rolling path 32. Specifically, the second spiral groove 23 has a pitch P2 that is larger than the pitch P1 of the rolling path 32. As a result, the dimensions D, E, and F between the second spiral groove 23 and the adjacent rolling path 32 on one axial side are gradually reduced. In other words, the second spiral groove 23 of the nut 20 in which the cooling pipe 40 is arranged is structured to gradually approach the rolling path 32 toward one axial direction.

The ball screw device 500 according to the fifth embodiment can be cooled more effectively when used in a situation where the balance of the load acting in the axial direction gradually increases toward one side in the axial direction.

In the case of the ball screw device 500 according to the fifth embodiment, as shown in FIG. 9, it is preferable that the cooling pipe 40 placed in the second spiral groove 23 has an outer diameter that does not protrude from the inner peripheral surface of the second land portion 22 of the nut 20 in which the second spiral groove 23 is formed.

In the fifth embodiment, the second spiral groove 23 is formed only in the second land portion 22 of the nut 20, and the cooling pipe 40 is disposed in this second spiral groove 23. However, the first spiral groove 13 may be formed only in the first land portion 12 of the screw shaft 10, and the cooling pipe 40 may be disposed in this first spiral groove 13. In this case, the cooling pipe 40 fixed to the screw shaft 10 has an outer diameter that does not contact the nut 20 facing the fixed side when fixed to the first spiral groove 13, and a gap is provided between the cooling pipe 40 and the second land portion 22 of the nut 20.

In addition, even when a cooling pipe 40 is provided on the screw shaft 10 side, it is preferable that the cooling pipe 40 to be placed in the first spiral groove 13 has an outer diameter that does not protrude from the outer peripheral surface of the first land portion 12 of the screw shaft 10 in which the first spiral groove 13 is formed (see Figure 9).

In the ball screw devices 100, 200, and 300 according to the first to third embodiments, the first spiral groove 13 and the second spiral groove 23 may be formed to have a different pitch P2 relative to the pitch P1 of the rolling path 32. In this case, cooling can be more effective when used in a situation where the balance of the load acting in the axial direction gradually increases toward one side of the axial direction.

As such, the present invention is not limited to the above-described embodiment, and the invention also contemplates the mutual combination of the various components of the embodiment, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known technology, and these are included in the scope of the protection sought.

As described above, the present specification discloses the following:
(1) A screw shaft having a helical screw groove on an outer circumferential surface thereof;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
The screw shaft and the nut have mutually opposing spiral grooves formed in the land portions between the rolling paths,
A ball screw device, wherein a cooling pipe is disposed in the spiral groove of the screw shaft or the nut.
In this ball screw device, a spiral groove is formed in the land portion of the screw shaft and the nut, and a cooling pipe is arranged in the spiral groove of the screw shaft or the nut. This allows the cooling pipe to cool the rolling path, which is the heat source, along the spiral groove, suppressing heat generation in the rolling path with high cooling efficiency, suppressing abnormal load distribution of the balls and deterioration of operability due to thermal deformation of the screw shaft or the nut, and maintaining high precision as a feed mechanism.
In addition, the spiral groove in which the cooling pipe is arranged can be easily machined when the screw groove is formed, so costs can be reduced compared to a structure in which a long and thin cooling liquid passage hole is formed in the axial direction of the nut. Moreover, compared to a structure in which the cooling pipe is arranged in a grinding relief groove, a cooling pipe with a large diameter (about four times larger) can be arranged in a spiral shape, and the cooling efficiency can be significantly improved (about four times or more).

(2) The ball screw device according to (1), wherein the cooling pipe has an outer diameter such that the cooling pipe does not come into contact with the screw shaft or the nut facing a fixed side when fixed to the spiral groove.
According to this ball screw device, interference with the screw shaft or the nut that faces the fixed side of the cooling pipe can be avoided, and the screw shaft and the nut can be smoothly rotated relative to each other.

(3) The ball screw device according to (1) or (2), wherein the spiral groove is formed at a position biased toward the rolling path adjacent to one side.
According to this ball screw device, for example, in the case where a large load is always applied to one flank of the rolling path, a spiral groove is formed near the flank of the rolling path that receives the large load, and a cooling pipe is arranged therebetween, so that heat generated in the rolling path can be more efficiently suppressed.

(4) The ball screw device according to any one of (1) to (3), wherein the spiral groove has a pitch different from a pitch of the rolling path.
According to this ball screw device, it is possible to more effectively cool the ball screw device when the device is used in a situation where the balance of the load acting in the axial direction gradually increases toward one side in the axial direction.

(5) A screw shaft having a helical screw groove on an outer circumferential surface thereof;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
A spiral groove is formed in a land portion between the rolling paths in the screw shaft or the nut,
A ball screw device, wherein a cooling pipe is disposed in the spiral groove.
In this ball screw device, a spiral groove is formed in the land portion of the screw shaft or the nut, and a cooling pipe is arranged in this spiral groove. This allows the cooling pipe to cool the area between the rolling paths, which are the heat source, along the spiral groove, suppressing heat generation in the rolling paths with high cooling efficiency, suppressing abnormal load distribution on the balls and deterioration of operability due to thermal deformation of the screw shaft or nut, and maintaining high precision as a feed mechanism.
In addition, the spiral groove in which the cooling pipe is arranged can be easily machined when the screw groove is formed, so costs can be reduced compared to a structure in which a long and thin cooling liquid passage hole is formed in the axial direction of the nut. Moreover, compared to a structure in which the cooling pipe is arranged in a grinding relief groove, a cooling pipe with a large diameter (about four times larger) can be arranged in a spiral shape, and the cooling efficiency can be significantly improved (about four times or more).

(6) The ball screw device according to (5), wherein the cooling pipe has an outer diameter such that the cooling pipe does not come into contact with the screw shaft or the nut facing a fixed side when the cooling pipe is fixed to the spiral groove.
According to this ball screw device, interference with the screw shaft or the nut that faces the fixed side of the cooling pipe can be avoided, and the screw shaft and the nut can be smoothly rotated relative to each other.

(7) The ball screw device according to (5) or (6), wherein the spiral groove is formed at a position biased toward the rolling path adjacent to one side.
According to this ball screw device, for example, in the case where a large load is always applied to one flank of the rolling path, a spiral groove is formed near the flank of the rolling path that receives the large load, and a cooling pipe is arranged therebetween, so that heat generated in the rolling path can be more efficiently suppressed.

(8) The ball screw device according to any one of (5) to (7), wherein the spiral groove has a pitch different from a pitch of the rolling path.
According to this ball screw device, it is possible to more effectively cool the ball screw device when the device is used in a situation where the balance of the load acting in the axial direction gradually increases toward one side in the axial direction.

10 Screw shaft 11 First screw groove (thread groove)
12 First land section (land section)
13 First spiral groove (spiral groove)
20 Nut 21 Second screw groove (screw groove)
22 Second land section (land section)
23 Second spiral groove (spiral groove)
30 Ball 32 Rolling path 40 Cooling pipe 100, 200, 300, 400, 500 Ball screw device P1, P2 Pitch

Claims (8)

A screw shaft having a helical screw groove on an outer circumferential surface thereof;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
The screw shaft and the nut have mutually opposing spiral grooves formed in the land portions between the rolling paths,
A cooling pipe is disposed in the spiral groove of the screw shaft or the nut.
Ball screw device. The cooling pipe has an outer diameter that does not contact the screw shaft or the nut facing the fixed side when the cooling pipe is fixed to the spiral groove.
The ball screw device according to claim 1 . The spiral groove is formed at a position biased toward the rolling path adjacent to one side.
The ball screw device according to claim 1 or 2. The spiral groove has a pitch different from the pitch of the rolling path.
The ball screw device according to any one of claims 1 to 3. A screw shaft having a helical screw groove on an outer circumferential surface thereof;
A nut having a helical thread groove on an inner peripheral surface and fitted onto the screw shaft;
A plurality of balls are accommodated in a rolling path formed by the screw shaft and the screw groove of the nut;
A ball screw device comprising:
A spiral groove is formed in a land portion between the rolling paths in the screw shaft or the nut,
A cooling pipe is disposed in the spiral groove.
Ball screw device. The cooling pipe has an outer diameter that does not contact the screw shaft or the nut facing the fixed side when the cooling pipe is fixed to the spiral groove.
The ball screw device according to claim 5. The spiral groove is formed at a position biased toward the rolling path adjacent to one side.
The ball screw device according to claim 5 or 6. The spiral groove has a pitch different from the pitch of the rolling path.
The ball screw device according to any one of claims 5 to 7.

Images