JP2018091436A - Ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball screw device which suppresses a pressure loss even if using radial oil feed holes which are distant from a lubricant flow-in port, and can supply a proper amount of the lubricant to each place in a ball nut by homogenizing a discharge amount of the lubricant.SOLUTION: A ball screw device has a plurality of balls 15 which are rollingly arranged between a spiral groove 12 of a ball screw shaft 11 and a spiral groove 14 of a ball nut 13, and includes an axial oil feed hole 17 having a lubricant flow-in port 17a at one end part of the ball screw shaft 11, and internally arranged along an axial direction, and a plurality of radial oil feed holes 18 which communicate with the axial oil feed hole 17, and supply a lubricant supplied to the axial oil feed hole 17 to the screw groove 12. The radial oil feed holes 18 are inclined with respect to a vertical direction of the axial oil feed hole 17, and the radial oil feed holes 18 communicate with the radial oil feed holes 18 which are the nearest to the lubricant flow-in port 17a from a communication position communicating with the axial oil feed hole 17, or from the vicinity of the communication position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a ball screw device used in a machine tool or the like.

  Ball screw devices used in machine tools and the like generally allow a large number of balls to roll between a screw groove formed on the outer peripheral surface of the ball screw shaft and a screw groove formed on the inner peripheral surface of the ball nut. For example, when a rotational torque about the axis is applied to the ball screw shaft, a large number of balls roll between the screw grooves of the ball screw shaft and the ball nut, and the ball nut is moved accordingly. It reciprocates in the axial direction of the ball screw shaft.

  Since such a ball screw device causes a decrease in positioning accuracy when wear occurs in the thread groove or the ball, for example, in Patent Document 1, in order to suppress wear of the thread groove or the ball, One axial oil supply hole extending in the axial direction inside and a plurality of radial oil supply holes communicating with the axial oil supply hole and extending in the radial direction (vertical direction) and opening in the screw groove are formed. The lubricant is supplied through the axial oil supply holes and the radial oil supply holes. The axial oil supply hole has a lubricant inlet opening at one end of the ball screw shaft and a terminal closed at the other end, and oil is supplied from the lubricant inlet.

  And if the hole position of the radial oil supply hole is close to the lubricant inlet, the amount of oil discharged from the radial oil supply hole is large. The oil supply holes are made different from each other according to the position in the axial direction so that the amount of oil discharged from each oil supply hole is equalized as compared with the case where all the oil supply holes have the same inner diameter.

JP 2003-269569 A

However, since the axial oil supply hole and the radial oil supply hole intersect at right angles, pressure loss occurs, and the oil supply amount in the radial direction farther away from the lubricant inflow port decreases the amount of oil discharged. There was a problem that.
The present invention has been made paying attention to the above-mentioned problems, and its purpose is to suppress pressure loss even in the case of a radial oil supply hole far from the lubricant inlet, An object of the present invention is to provide a ball screw device capable of supplying an appropriate amount of lubricant to various locations inside the ball nut by making the discharge amount of the agent uniform.

In order to achieve the above object, the present invention provides a ball screw shaft having a spiral groove provided on an outer peripheral surface, a ball nut having a spiral groove provided on an inner peripheral surface and through which the ball screw shaft passes, and the screw A plurality of balls that roll in a rolling path formed by the spiral groove of the shaft and the spiral groove of the ball nut, and a lubricant inlet at one end of the screw shaft, and the axial direction of the ball screw shaft And a plurality of radial oil supply holes that communicate with the axial oil supply hole and supply the lubricant supplied to the axial oil supply hole to the thread groove of the ball screw shaft. And the radial oil supply hole is formed in an inclined shape with respect to the vertical direction of the axial oil supply hole, and the respective radial oil supply holes are , Radial oil supply hole and axial direction closest to the lubricant inlet Communicating the position of the oil supply hole, or characterized in that it communicates the vicinity thereof.
The present invention is characterized in that the diameters of the respective radial oil supply holes are made different according to the axial position of the ball screw shaft.

  According to the present invention, even in the case of a radial oil supply hole that is far from the lubricant inlet, pressure loss is suppressed, and the amount of lubricant discharged is made uniform so that an appropriate amount can be provided at various locations inside the ball nut. A ball screw device capable of supplying a lubricant can be provided.

It is a schematic sectional drawing of the ball screw apparatus which concerns on one Embodiment of this invention. It is a figure which shows the elements on larger scale of the area | region shown with the code | symbol A in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are diagrams for explaining an embodiment of the present invention. FIG. 1 is a schematic sectional view of a ball screw according to an embodiment of the present invention. FIG. 2 is a region indicated by reference numeral A in FIG. FIG.
As shown in FIG. 1, a ball screw device 1 according to an embodiment of the present invention includes a ball screw shaft 11 having a spiral groove (screw groove) 12 provided on the outer peripheral surface, and a spiral groove (screw) on the inner peripheral surface. A rolling groove formed by a nut 13 through which the ball screw shaft passes, a spiral groove (screw groove) 12 of the ball screw shaft 11 and a spiral groove (screw groove) 14 of the ball nut 13. And a plurality of balls 15 rolling.
Although not shown, the ball nut 13 is provided with a ball circulation tube for returning the ball 15 that has rolled in the rolling path between the spiral grooves 12 and 14 to the initial position.

  In the present embodiment, the ball screw shaft 11 is provided with an axial oil supply hole 17 and a plurality of radial oil supply holes 18 as lubricant supply means for supplying a lubricant to the ball 15. Specifically, as shown in FIG. 2, an axial oil supply hole 17 having a lubricant inlet 17 a at one end portion of the ball screw shaft 11 and being installed along the axial direction of the ball screw shaft 11, It is configured to include a plurality of radial oil supply holes 18 that communicate with the direction oil supply hole 17 and supply the lubricant supplied to the axial oil supply hole 17 to the spiral groove 12 of the ball screw shaft 11.

  The axial oil supply hole 17 is formed in the axial center portion of the ball screw shaft 11 along the axial direction of the ball screw shaft 11. Further, as shown in FIG. 1, the axial oil supply hole 17 has a lubricant inlet 17a opened at one end of the ball screw shaft 11, and a lubricant supply mechanism 20 is provided in the lubricant inlet 17a. It is connected. Note that the other end of the axial oil supply hole 17 is a closed end within the ball screw shaft 11.

  The radial oil supply hole 18 starts from the axial oil supply hole 17 on the inner surface side of the ball screw shaft 11, and is inclined with respect to the vertical direction of the axial oil supply hole 17. See). An opening end of the radial oil supply hole 18 is provided at the groove bottom 12 a of the spiral groove 12. And each radial direction oil supply hole 18 is connected from the communication position of the radial direction oil supply hole 18 and axial direction oil supply hole 17 nearest to the lubricant inflow port 17a, or its vicinity position.

In such a configuration, when the lubricant is supplied from the lubricant supply mechanism 20 to the axial oil supply hole 17 (lubricant inlet 17a), the lubricant supplied to the axial oil supply hole 17 is reduced in diameter of the ball screw shaft 11. 2 flows in the respective radial oil supply holes 18a, 18b, 18c (in the direction of arrow P in FIG. 2), and flows through the respective radial oil supply holes 18 to the groove bottom portion 12a of the screw groove 12. leak.
Therefore, in this embodiment, it becomes possible to supply the lubricant to the ball 15 incorporated between the spiral groove 12 of the ball screw shaft 11 and the spiral groove 14 of the ball nut 13. Even when the automatic oiling device cannot be attached, the lubricant can be supplied to the spiral groove 12 of the ball screw shaft 11 to suppress wear of the ball or the like.

  Further, in this embodiment, the starting position where the lubricant is supplied to the radial oil supply holes 18a, 18b, 18c is most different from the lubricant inlet 17a, and is the position of the radial oil supply hole 18a. Only one place is formed, and the radial oil supply holes 18a, 18b, and 18c communicate with each other. This starting position is the point where the cylindrical axis center lines of the cylindrical radial oil supply holes 18a, 18b, 18c intersect or the vicinity Q thereof. In this way, by gathering in the vicinity of the radial oil supply hole Q from the axial oil supply hole entrance, the amount of lubricant discharged from each radial oil supply hole can be made uniform.

The radial oil supply hole 18a is a cylindrical hollow and is formed as an oil supply hole in the radial direction, and the distance to the groove bottom 12a of the screw groove 12 that is the opening end of the radial oil supply hole 18 is the radial oil supply hole 18a, 18b. , 18c is the shortest.
The radial oil supply hole 18b, which is the same as the starting position to which the lubricant is supplied in the radial oil supply hole 18a, is inclined with respect to the vertical direction of the ball screw shaft 11, and the groove bottom 12b of the radial oil supply hole 18b. Is longer than the radial oil supply hole 18a and shorter than that of the radial oil supply hole 18c.
The radial oil supply hole 18c, which is the same as the starting position to which the lubricant is supplied in the radial oil supply hole 18a, is further inclined with respect to the vertical direction of the ball screw shaft 11 from the radial oil supply hole 18b. The distance of the hole 18c to the groove bottom 12c is longer than the radial oil supply holes 18a, 18b. That is, the distance between the groove bottom portions 12b and 12c communicating with the radial oil supply holes 18b and 18c is determined according to the pitch (lead) length of the screw groove 12, and from the groove bottom portion 12a of the radial oil supply hole 18a. It gets longer as you leave.
In the present embodiment, the radial oil supply holes 18a are not inclined, but an embodiment in which the radial oil supply holes 18b and 18c are inclined is also within the scope of the present invention. That is, there may be no vertical radial oil supply holes, and all directional oil supply holes may be inclined.

  Further, the diameters of the respective radial oil supply holes 18 are made different according to the axial position of the ball screw shaft 1. For example, if the distance between the respective opening ends of the radial oil supply holes 18a, 18b, 18c is short, the lubricant can be sufficiently distributed even if the hole diameter is small, and conversely, the respective openings of the radial oil supply holes 18a, 18b, 18c. If the distance between the mouths is long, the hole diameter can be increased to spread more lubricant.

  In the present embodiment, the oil supply holes are formed so that the radial oil supply holes 18b, 18c and the groove bottom portions 12b, 12c communicate with each other. However, in consideration of not interfering with the rolling surface of the ball 15 of the screw shaft 11. The number, the position, and the inclination angle can be determined, and for example, it can be provided on the outer diameter of the ball screw shaft 11 or the land between the spiral grooves 12. That is, the radial oil supply hole 18 is not limited to the above-described embodiment, and does not interfere with the rolling surface of the ball 15 of the ball screw shaft 11 in any part of the ball screw shaft 11 facing the ball nut 13. May also be provided.

As described above, not only the diameters of the radial oil supply holes 18a, 18b, 18c, which are radial oil supply holes, are changed according to the position in the axial direction, but also the respective radial oil supply holes 18a, 18b, 18c are lubricated. The radial oil supply hole 18b, which is inclined with respect to the vertical direction of the axial oil supply hole 17, at the communication position of the radial oil supply hole 18 closest to the agent inlet 17a and the axial oil supply hole 17 or a position Q in the vicinity thereof. By connecting 18c and the radial oil supply hole 18a, pressure loss is suppressed, and the lubricant discharge amount is made uniform, so that an appropriate amount of lubricant is applied to various locations inside the ball nut.
In addition, the effect of each radial direction oil supply hole 18 does not change even if it faces in any direction of the vertical direction (up and down in the drawing) or the direction perpendicular to the vertical direction (left and right in the drawing).

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation can be implemented.

1 Ball screw device 11 Ball screw shaft 12 Spiral groove (thread groove of ball screw shaft)
13 Ball nut 14 Spiral groove (screw groove of ball nut)
15 Ball 17 Axial lubrication hole 18 Radial lubrication hole 20 Lubricant supply mechanism

Claims (2)

A screw shaft provided with a spiral groove on the outer peripheral surface;
A nut provided with a spiral groove on the inner peripheral surface and through which the screw shaft passes;
A plurality of balls rolling in a rolling path formed by the spiral groove of the screw shaft and the spiral groove of the nut;
An axial oil supply hole that has a lubricant inlet at one end of the ball screw shaft and is provided along the axial direction of the ball screw shaft;
A ball screw device configured to include a plurality of radial oil supply holes that communicate with the axial oil supply hole and supply the lubricant supplied to the axial oil supply hole to the thread groove of the ball screw shaft. Because
The radial oil supply holes are formed so as to be inclined with respect to the vertical direction of the axial oil supply holes, and the respective radial oil supply holes are axially aligned with the radial oil supply holes closest to the lubricant inlet. A ball screw device, wherein the ball screw device communicates with the oil supply hole from the communication position or the vicinity thereof. 2. The ball screw device according to claim 1, wherein the diameters of the respective radial oil supply holes are made different according to an axial position of the ball screw shaft.

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