JP6589504B2 - Ball screw - Google Patents

Description

  The present invention relates to a ball screw, and more particularly to a ball screw used for a machine tool or the like.

  Conventionally, a ball screw having a screw shaft and a nut screwed onto the screw shaft via a plurality of rolling elements (for example, balls), the screw shaft and the nut being relatively rotatable. Is used. In this ball screw, frictional heat due to point contact or surface contact is generated between the screw shaft and the nut during rotation, and therefore cooling means for cooling the frictional heat may be provided.

  As a ball screw provided with such a cooling means, there is a technique disclosed in Patent Document 1. The technique described in Patent Document 1 is a technique in which a cooling medium is passed through a cooling flow path provided in a nut along the axial direction to cool the nut.

JP 2002-310258 A

However, in the technique described in Patent Document 1, in order to circulate the cooling medium in the nut, it is necessary to process a cooling flow path in the nut. Therefore, it is difficult to process the cooling flow path in a nut having a long axial dimension.
Further, since the cooling flow path is provided on the radially outer side of the load circulation path where the ball (rolling element) rolls, the outer diameter of the nut increases.
Furthermore, in the technique described in Patent Document 1, since cooling and lubrication are performed by separate mechanisms, a facility for circulation is required for both lubrication and cooling.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a ball screw having high cooling efficiency without using a separate mechanism for cooling and lubrication, without increasing the size of the nut. .

A certain aspect of the ball screw for achieving the above object includes a screw shaft extending in the axial direction and provided with a helical spiral groove on the outer peripheral surface;
A cylindrical nut having a spiral groove opposite to the spiral groove on the inner peripheral surface and screwed to the screw shaft via a plurality of balls disposed between the spiral groove and the spiral groove of the screw shaft When,
A seal member provided at both ends of the nut in the axial direction and having an annular shape and interposed between the outer peripheral surface of the screw shaft and the inner peripheral surface of the nut;
A plurality of annular grooves formed inside the seal member on the inner peripheral surface of the nut;
A discharge hole communicating with the groove portion and penetrating radially through the outer peripheral surface of the nut;
The nut has a helical groove and an oil supply hole that penetrates the outer peripheral surface of the nut in the radial direction and is formed between the plurality of grooves in the axial direction.

Here, in the ball screw, a plurality of the discharge holes may be further provided inside.
Further, in the ball screw, the oil supply hole is provided closer to any of the plurality of seal members than the central portion in the axial direction of the nut, and the discharge hole is formed based on the installation position of the oil supply hole. Further, it may be provided.

In the ball screw, a plurality of annular air pockets formed inside the seal member on the inner peripheral surface of the nut,
An air hole communicating with the air pocket and penetrating in the radial direction may be provided on the outer peripheral surface of the nut.
In the ball screw, the seal member may be a labyrinth seal, and a suction device may be connected to the discharge hole.

  According to one embodiment of the present invention, it is possible to provide a ball screw with high cooling efficiency without using a separate mechanism for cooling and lubrication, without increasing the size of the nut.

It is a figure which shows the structure in 1st Embodiment of a ball screw, (a) is sectional drawing which follows an axial direction, (b) is the side view seen from the axial direction. It is sectional drawing which follows the axial direction which shows the structure in 2nd Embodiment of a ball screw. It is sectional drawing which follows the axial direction which shows the structure in 3rd Embodiment of a ball screw. It is sectional drawing which follows the axial direction which shows the structure in 4th Embodiment of a ball screw. It is sectional drawing which follows the axial direction which shows the structure in 5th Embodiment of a ball screw.

Hereinafter, embodiments of the ball screw will be described with reference to the drawings.
(First embodiment)
1A and 1B are diagrams showing a configuration of a ball screw according to a first embodiment, wherein FIG. 1A is a cross-sectional view taken along the axial direction, and FIG. 1B is a side view seen from the axial direction.
As shown in FIG. 1A, the ball screw 1 of this embodiment includes a screw shaft 10, a nut 20, a plurality of rolling elements (for example, balls) 30, a seal member 40, a groove portion 50, and a discharge. It has a hole 51 and an oil supply hole 60.

<Nut>
The nut 20 has a main body portion 20A formed in a cylindrical shape with an inner diameter larger than the outer diameter of the screw shaft 10, and a flange portion 20B extended in the radial direction at an end portion of the main body portion 20A.
A spiral groove 21 is formed on the inner peripheral surface 20 a of the nut 20 so as to face the spiral groove 11 formed in a spiral shape on the outer peripheral surface 10 a of the screw shaft 10. These spiral grooves 11 and 21 preferably have a Gothic arch shape.
The screw shaft 10 and the nut 20 are screwed together by a plurality of rolling elements 30 disposed between the spiral groove 11 and the spiral groove 21. In this way, the rolling element 30 can roll on the load rolling path formed by the spiral groove 11 and the spiral groove 21, and the screw shaft 10 and the nut 20 can be relatively moved in the axial direction.

<Seal member>
Further, at both ends in the axial direction of the nut 20, a contact-type seal member that seals an annular gap between the inner peripheral surface 20 a of the nut 20 and the outer peripheral surface 10 a (including the spiral groove 11) of the screw shaft 10. 40 are respectively provided. The seal member 40 is installed on the inner peripheral surface 20a of the nut 20 so as to be in non-contact with the outer peripheral surface 10a of the screw shaft 10 with a predetermined gap.
Here, the fastening allowance with respect to the screw shaft 10 of the sealing member 40 is preferably 0.1 to 0.3 mm.

<Groove>
An annular groove 50 is provided on the inner peripheral surface 20 a of the nut 20, one on each inner side of the plurality of seal members 40, corresponding to the seal members 40. That is, when one pair of seal members 40 is provided at both ends of the nut 20 in the axial direction, one pair corresponding to each seal member 40, 40, one pair of grooves 50A, 50B. Is provided.
Here, the above “inner side” refers to the opposite side when the end side of the nut 20 is “outer side” with the seal member 40 as a reference. That is, when one pair of seal members 40 are provided at both axial ends of the nut 20, the groove portions 50 </ b> A and 50 </ b> B are provided so as to be sandwiched between the seal members 40 and 40 in the axial direction.

<Discharge hole>
The discharge hole 51 communicates with the groove portion 50 and is provided so as to penetrate the outer peripheral surface 20b of the nut 20 in the radial direction. That is, the discharge hole 51 is provided so as to penetrate the inner peripheral surface 20a and the outer peripheral surface 20b of the nut 20 via the groove portion 50 opened in the inner peripheral surface 20a of the nut 20.
The discharge hole 51 is injected into an oil supply hole 60 which will be described later, and has a function of discharging the lubricating oil responsible for lubrication and cooling between the screw shaft 10 and the nut 20.
The kinematic viscosity of the lubricating oil used in the present embodiment is preferably 15 to 100 mm ² / s in consideration of a rapid cooling function. The lubricating oil used in the present embodiment is preferably a lubricating oil having an ISO viscosity classification in the range of “VG32” to “VG220”.

  Here, the discharge holes 51A and 51B provided in a pair in the axial direction corresponding to the groove portion 50 are 240 ° / 360 ° in the circumferential direction of the nut 20 as viewed from the axial direction, as shown in FIG. It is preferable to be provided in the range. The discharge holes 51A and 51B are more preferably installed in the same phase when viewed from the axial direction.

<Oil filling hole>
The oil supply hole 60 penetrates the spiral groove 21 of the nut 20 and the outer peripheral surface 20b of the nut 20 in the radial direction, and is formed between the plurality of groove portions 50A and 50B in the axial direction.
The oil supply hole 60 is preferably provided in the vicinity of the intermediate portion of the nut 20 in the axial direction. Thus, by providing the oil supply hole 60 near the center of the nut 20 in the axial direction, there is an effect that the lubricating oil supplied from the oil supply hole 60 flows in a balanced manner in a direction away from the axial direction. Therefore, a large amount of lubricating oil can be poured into the oil supply hole 60, and a high cooling effect and foreign matter discharge can be realized simultaneously with lubrication.

Further, as shown in FIG. 1B, the oil supply hole 60 is preferably provided in a range of 120 ° / 360 ° in the circumferential direction of the nut 20 as viewed from the axial direction (hatched portion in the figure). The oil supply hole 60 is more preferably installed on the side opposite to the discharge hole 51 when viewed from the axial direction.
Furthermore, when the “relief groove” is formed in the spiral groove 21 of the nut 20, the oil supply hole 60 is preferably provided corresponding to this “relief groove”.

As described above, according to the present embodiment, both ends of the nut 20 are sealed together with the screw shaft 10 with the seal members 40 and 40, and the groove portion 50 communicating with the discharge hole 51 is provided. Even if it is poured, it can be discharged.
Thus, since it was set as the structure which can be discharged even if it inject | pours a lot of lubricating oil, a lot of lubricating oil can be supplied in the nut 20. FIG. As a result, the cooling and lubrication of the ball screw 1 and the discharge of foreign matter in the nut 20 can be performed simultaneously. Thereby, it is not necessary to provide a member for cooling, the ball screw can be made compact, and the manufacturing cost can be suppressed.
Therefore, it is possible to provide a ball screw with high cooling efficiency without using a separate mechanism for cooling and lubrication, without increasing the size of the nut.

Further, by providing the oil supply hole 60 near the center in the axial direction, the lubricating oil flows in the respective directions in the axial direction, so that the lubricating oil is supplied into the nut in a well-balanced manner.
Further, since the lubricating oil is used for cooling, the portion of the ball screw 1 that is likely to generate heat can be directly cooled with the lubricating oil, and a high cooling effect is achieved.
Further, since a large amount of lubricant is allowed to flow, foreign matter in the nut 20 can be washed out.

(Second Embodiment)
Next, a second embodiment of the ball screw will be described with reference to the drawings. In the present embodiment, the same members and parts as those in the first embodiment described above are denoted by the same reference numerals, and redundant description thereof is omitted. That is, this embodiment is a ball screw having a structure equivalent to that of the first embodiment, in which the mode of the discharge hole is changed.

FIG. 2 is a cross-sectional view along the axial direction showing the configuration of the second embodiment of the ball screw.
As shown in FIG. 2, the ball screw of the present embodiment further includes a plurality of groove portions 50C and 50D on the inner side of the groove portions 50A and 50B of the nut 20 to which the sealing members 40 and 40 of the sealing specification are mounted. The groove portions 50C and 50D communicate with discharge holes 51C and 51D penetrating the outer peripheral surface 20b of the nut 20, respectively.

  With such a configuration, the discharge capacity is higher than that in the first embodiment, and more lubricating oil can be supplied. As a result, it is possible to provide a ball screw having a higher cooling effect and a foreign matter discharging effect.

(Third embodiment)
Next, a third embodiment of the ball screw will be described with reference to the drawings. In the present embodiment, the same members and parts as those in the first embodiment described above are denoted by the same reference numerals, and redundant description thereof is omitted. That is, this embodiment is a ball screw having a structure equivalent to that of the first embodiment, in which the modes of the oil supply hole, the groove portion, and the discharge hole are changed.

FIG. 3 is a cross-sectional view along the axial direction showing the configuration of the third embodiment of the ball screw.
As shown in FIG. 3, in the ball screw of the present embodiment, the installation position of the oil supply hole 60 is provided closer to one of the plurality of seal members 40, 40 than the central portion in the axial direction of the nut 20. Then, along with the uneven installation position of the oil supply hole 60, the groove portion 50 </ b> C and the discharge hole 51 </ b> C communicating with the groove portion 50 </ b> C are provided on the same side in the axial direction. The number of the groove portions 50 and the discharge holes 51 is not limited to one and may be plural.

  With such a configuration, even when the oil supply hole 60 is not provided in the vicinity of the center of the nut 20 in the axial direction, it is possible to discharge the lubricating oil without unevenness, and a high cooling effect and foreign matter discharge are possible. .

(Fourth embodiment)
Next, a fourth embodiment of the ball screw will be described with reference to the drawings. In the present embodiment, the same members and parts as those in the first embodiment described above are denoted by the same reference numerals, and redundant description thereof is omitted. That is, this embodiment is a mode in which an air hole is further provided in the ball screw having the same structure as that of the first embodiment.

FIG. 4 is a cross-sectional view along the axial direction showing the configuration of the fourth embodiment of the ball screw.
As shown in FIG. 4, the ball screw of the present embodiment is provided with a plurality of annular air pockets 70 </ b> A and 70 </ b> B inside the seal members 40 and 40 on the inner peripheral surface 20 a of the nut 20.
The air pockets 71A and 71B communicate with the air pockets 70A and 70B, respectively, and are provided in the outer peripheral surface 20b of the nut 20 in a radial direction. Here, it is preferable that the outside of the air holes 71A and 71B has a minute clearance s and the inside has a normal clearance. Further, as one of the air holes 71, an air hole 71 </ b> C that penetrates the land portion of the inner peripheral surface 20 a of the nut 20 and the outer peripheral surface of the nut 20 may be provided.

  By having such a configuration, there is an effect that the lubricating oil discharge capacity is further increased by the pressure of the air. Further, by setting the outside of the nut 20 as a minute gap s and the inside of the nut 20 as an air pocket 70 (70A, 70B), the air flows inside the nut 20 and the lubricating oil leaks from the end of the nut 20. Can be prevented.

(Fifth embodiment)
Next, a fifth embodiment of the ball screw will be described with reference to the drawings. In the present embodiment, the same members and parts as those in the first embodiment described above are denoted by the same reference numerals, and redundant description thereof is omitted. That is, this embodiment is a ball screw having a structure equivalent to that of the first embodiment, in which the aspect of the seal member is changed.

FIG. 5 is a cross-sectional view along the axial direction showing the configuration of the fifth embodiment of the ball screw.
As shown in FIG. 5, the ball screw according to the present embodiment has a mode in which a suction device (not shown) is connected to a discharge hole 51 provided in the nut 20 for suction. The suction by the suction device increases the discharge capacity by sucking the lubricating oil slightly more than the amount of oil supplied in the oil supply hole 60. Therefore, as shown in FIG. 5, even when the labyrinth seal 41 is employed as the seal member, a high cooling effect and foreign matter discharge effect can be obtained.

  Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the claims encompass these modifications and embodiments that fall within the scope and spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Ball screw 10 Screw shaft 10a (Screw shaft) outer peripheral surface 11 (Screw shaft) spiral groove 20 Nut 20a (Nut) inner peripheral surface 20b (Nut) outer peripheral surface 21 (Nut) spiral groove 30 Rolling element ( ball)
40 Seal member 50 Groove 51 Discharge hole 60 Oil supply hole 70 Air pocket 71 Air hole

Claims (4)

A screw shaft extending in the axial direction and provided with a spiral groove on the outer peripheral surface;
A cylindrical nut having a spiral groove facing the spiral groove on the inner peripheral surface, and screwed into the screw shaft via a plurality of balls disposed between the spiral groove and the spiral groove of the screw shaft When,
A seal member provided at both ends of the nut in the axial direction and having a ring shape and interposed between an outer peripheral surface of the screw shaft and an inner peripheral surface of the nut;
A plurality of annular grooves formed inside the seal member on the inner peripheral surface of the nut;
A discharge hole communicating with the groove portion and penetrating radially through the outer peripheral surface of the nut;
Wherein the outer peripheral surface of the spiral groove and the nut of the nut penetrates radially, it possesses a lubrication hole formed between said plurality of grooves in the axial direction,
A ball screw, wherein a plurality of the discharge holes are further provided inside . The oil supply hole, near provided on either of said plurality of sealing members than the central portion in the axial direction of the nut, based on the installation position of the oil supply hole, according to claim 1, wherein the discharge hole is further provided Ball screw. A plurality of annular air pockets formed inside the seal member on the inner peripheral surface of the nut;
The communication with the air pocket, ball screw according to claim 1 or 2 air hole penetrating in the radial direction provided on the outer peripheral surface of the nut. The ball screw according to any one of claims 1 to 3 , wherein the seal member is a labyrinth seal, and a suction device is connected to the discharge hole.

Images