JPH06201015A - Ball screw lubrication method and device - Google Patents

Abstract

PURPOSE:To provide a lubrication method and device for a ball screw with a screw shaft rotationally driven which ensures forcible lubrication over a long period with a simple structure. CONSTITUTION:A lubricant filled portion 7 is provided in a screw shaft 2 so as to extend in the axial direction of the screw shaft 2. The lubricant filled portion 7 is provided with lubricant supply holes 8, 8,... communicated with a spiral groove 3 so as to extend in the radial direction of the screw shaft 2. With centrifugal force caused by the rotational drive of the screw shaft 2, lubricant A is forcibly supplied directly to a ball track portion (between the spiral grooves 3, 5) via the lubricant supply holes 8, 8,....

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw lubrication method and device, and more particularly, to a ball screw in which a screw shaft is rotationally driven at a relatively high speed. Regarding technology.

[0002]

2. Description of the Related Art A conventional ball screw of this type is shown in FIG.
There is a structure as shown in. In this ball screw, a spiral groove b is formed on the outer peripheral surface of the screw shaft a, and a spiral groove d is formed on the inner peripheral surface of a nut body c fitted on the screw shaft a. , A plurality of balls e between d,
e, ... Are rotatably interposed. Also, the nut body c
At both ends of the rolling portion of the ball in the spiral groove d, return tubes (not shown) are connected to form a ball circulation path.

When the screw shaft a is rotationally driven, the screw shaft a and the nut body c are relatively rotated, and the balls e, e, ... The nut body c relatively moves in the axial direction with respect to the screw shaft a. Also, the spiral groove d of the nut body c
In the ball rolling portion of the ball, the ball e that has reached one end thereof moves to the other end through the ball circulation path and is circulated.

By the way, regarding lubrication of the ball screw,
Depending on the application location, there are some that are not lubricated, while others that require forced lubrication to ensure smooth drive.

As a method of this forced lubrication, as shown in FIG. 7, a lubricant introducing hole f is provided at one end of the nut body c, and the lubricant A is introduced into the nut body c through the lubricant introducing hole f. The method of injection is the mainstream.

When a low-viscosity lubricating oil is used as the lubricant A, the lubricating oil is injected into the nut body c through the lubricant introducing hole f. When a semi-solid lubricant such as highly viscous grease is used as the lubricant A, the grease or the like is pre-filled in the nut body c through the lubricant introduction hole f. g is an oil seal for sealing the nut body c.

[0007]

However, such a structure has the following problems, and its improvement has been demanded.

That is, when a low-viscosity lubricating oil is used as the lubricant, it is necessary to constantly inject the lubricating oil from the lubricant introducing hole f, and therefore, a lubricating oil supply means for constantly injecting the lubricating oil is separately provided. It was necessary, and the equipment used became complicated and large, and the running cost increased.

On the other hand, when a semi-solid lubricant such as grease is used as the lubricant, since the grease or the like is filled in the nut body c in advance, the above-mentioned lubricating oil supply means becomes unnecessary. However, on the other hand, since grease or the like cannot be forcibly supplied to the ball raceway portion (between both spiral grooves b and d), reliable lubrication of the ball and the ball raceway portion cannot be performed.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a ball screw lubrication method which has a simple structure and enables reliable forced lubrication over a long period of time. And to provide a lubrication device.

[0011]

In order to achieve this object, a ball screw lubrication method of the present invention is a method applied to a ball screw in which a screw shaft is rotationally driven. In addition to filling the lubricant, it is also possible to directly and forcibly supply this lubricant to the ball raceways through the lubricant supply hole that extends in the radial direction of the screw shaft, due to the centrifugal force generated as the screw shaft rotates. Characterize.

The ball screw lubrication device of the present invention comprises:
A device provided in a ball screw whose screw shaft is rotationally driven, wherein a lubricant filling portion is provided inside the screw shaft so as to extend in an axial direction of the screw shaft, and is in communication with the lubricant filling portion. A plurality of lubricant supply holes extend in the radial direction of the screw shaft and are opened so as to face the bottom of the ball raceway groove.

[0013]

By rotating the screw shaft, the screw shaft and the nut body rotate relative to each other, and the ball moves along the spiral groove which is the track of the ball. It returns to the other end and is recycled.

At this time, the lubricant filled in the screw shaft is urged by a centrifugal force generated by the rotation of the screw shaft to pass through a lubricant supply hole extending in the radial direction of the screw shaft and the raceway surface of the ball raceway portion. Directly and forcibly supplied to.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A ball screw equipped with a lubricating device according to the present invention will be described in detail below with reference to the drawings.

Embodiment 1 An embodiment of a ball screw provided with a lubricating device according to the present invention is shown in FIGS. 1 and 2, and the ball screw 1 comprises a screw shaft 2
While the spiral groove (ball raceway groove) 3 is provided on the outer peripheral surface of the screw body, the spiral groove (ball raceway groove) 5 is provided on the inner peripheral surface of the nut body 4 which is externally fitted to the screw shaft 2. A plurality of steel balls 6, between the grooves 3 and 5 (ball race)
6, ... are rotatably interposed. A ball circulation path (not shown) is formed in the outer peripheral portion of the nut body 4, and the balls 6, 6, ... Circulate through the ball circulation path.

The screw shaft 2 is rotationally driven by a driving means (not shown), and the rotational drive of the screw shaft 2 causes the screw shaft 2 and the nut body 4 to relatively rotate so that the ball The spiral groove 3, 6, 6, ...
Moved along 5.

Inside the screw shaft 2, as shown in FIG.
A hollow lubricant filling portion 7 is formed, and the lubricant filling portion 7 is formed.
Lubricant A is filled inside. This lubricant filling section 7
Is provided so as to extend in the axial direction of the screw shaft 2, and is specifically in the form of a cylindrical hole whose inner diameter has the same dimension over the entire length. Reference numeral 12 is a blind plug that seals the end of the lubricant filling portion 7 in a hermetic manner, and 15 is a grease nipple that supplies the lubricant A into the lubricant filling portion 7, which is provided at the base end of the lubricant filling portion 7. .

Further, the lubricant filling portion 7 has a plurality of lubricant supply holes 8, 8 for supplying the lubricant A filled in the screw shaft 2 between the spiral grooves 3, 5. Are provided with a predetermined pitch in the axial direction of the screw shaft 2 (or along the spiral groove 3). These lubricant supply holes 8, 8, ...
Are provided in an appropriate number within the range of the movement stroke L of the nut body 4.

The lubricant supply holes 8, 8, ... Are formed so as to extend in the radial direction of the screw shaft 2 and communicate with the spiral groove 3 of the screw shaft 2. That is, as shown in FIG. 3, one end 8a of the lubricant supply hole 8 is opened to face the lubricant filling portion 7, and the other end 8b is opened to face the bottom portion 3a of the spiral groove 3. Has been done.

The lubricant supply hole 8 is formed by electric discharge machining, a super hard drill or the like, and has an inner diameter of 0.1 to 1.0 mm.
The degree is appropriately set according to the usage conditions of the ball screw 1 and the like. For example, the hydraulic pressure is reduced in advance by, for example, setting the inner diameter of the lubricant supply hole 8 provided in the central portion of the lubricant filling portion 7 in the axial direction to be larger than the inner diameter of the lubricant supply hole 8 provided in another portion. The part is detected in advance, and the inner diameter of the lubricant supply hole 8 in that part is set to be larger than the inner diameters of the lubricant supply holes 8 provided in other parts. Reference numeral 9 denotes a polishing groove formed on the other end 8b side of the lubricant supply hole 8.

In the ball screw 1 having the lubricating device constructed as described above, the screw shaft 2 is rotationally driven to relatively rotate the screw shaft 2 and the nut body 4. , The balls 6, 6, ... Are moved along the spiral grooves 3, 5, which are the orbits thereof, while the nut body 4 is relatively moved in the axial direction of the screw shaft 2 within the range of the movement stroke L. become.

At this time, the lubricant A filled inside the screw shaft 2 is generated by the centrifugal force generated by the rotation of the screw shaft 2.
Are supplied between the spiral grooves 3 and 5 through the lubricant supply holes 8, 8, .... Therefore, when the lubricant A is supplied between the spiral grooves 3 and 5, the lubricant A is directly and forcibly applied without using a means (for example, a pump) forcibly supplying the lubricant A. In addition, it can be reliably supplied.

Since the lubricant A is supplied between the spiral grooves 3 and 5 by the centrifugal force generated by the rotation of the screw shaft 2, it is generally possible to use a lubricating oil having a relatively high viscosity. Although the lubricant A is prevented from scattering to the outside,
Specifically, the viscosity of the lubricant A is selected according to various conditions such as the number of revolutions of the screw shaft 2, the size of the lubricant supply hole 8, and the size of the outer diameter of the screw shaft 2. Further, by using the lubricant A having both lubricity and vibration absorption, it is possible to absorb the vibration generated by the high speed rotation of the screw shaft 2.

Example 2 This example is shown in FIG. 4, in which the inside diameter of the lubricant filling portion 7 is
The nut body 4 is set so as to gradually increase toward the center C of the moving stroke L of the nut body 4. Specifically, the cross-sectional shape of the inner peripheral surface 7a of the lubricant filling portion 7 is
With the center C of the moving stroke L of the nut body 4 as the apex,
It is formed in a curved shape in the axial direction of the screw shaft 2.

However, the lubricant filling portion 7 shown in FIG. 4 is drawn by emphasizing the above-mentioned curved shape, and is actually formed into a substantially straight and gently curved shape.

According to this example, the inner peripheral surface 7 of the lubricant filling portion 7 is
Since a is formed in a bulging shape with the center C of the movement stroke L of the nut body 4 as the apex, when a relatively viscous semi-solid lubricant such as lubricating oil or grease is used as the lubricant A Also, even when the rotation of the screw shaft 2 is relatively low, the centrifugal force accompanying the rotation of the screw shaft 2 effectively acts, and the lubricant A can be reliably supplied between the spiral grooves 3 and 5. .

Other configurations and operations are similar to those of the first embodiment.

Example 3 This example is shown in FIG. 5, and when the supply of the lubricant A to the spiral grooves 3 and 5 is desired to be further promoted, for example, as the lubricant A, semi-fixation of highly viscous lubricating oil or grease is performed. It is preferably used when a lubricant is used, and for increasing the oil pressure in the lubricant filling section 7 in the lubricant introducing section 10 provided at one end 7b of the lubricant filling section 7. The pressurizing means 11 is provided and the other end 7c of the lubricant filling portion 7 is sealed by a blind plug 12.

A screw member is preferably used as the pressurizing means 11, but it is also possible to use another device in place of this. The pressurizing means 11 can be manually screwed in the axial direction, and the pressurizing means 11 can be appropriately screwed in the axial direction (see the arrow a direction in FIG. 5) according to the decrease amount of the lubricant A. This increases the oil pressure in the lubricant filling section 7.

Other configurations and operations are similar to those of the first embodiment.

Embodiment 4 This embodiment is shown in FIG. 6, and the pressurizing means 11 in the above Embodiment 3 is used.
The adjustment of is automatically performed. In this example, the pressurizing means 11 has a sealing member 11a that is movable in the lubricant filling portion 7 in the axial direction, a compression spring 11b that elastically urges the sealing member 11a, and an adjusting screw 11c.
Consists of. Therefore, in the ball screw 1 in this example, the sealing member 11a is moved by the elastic force of the compression spring 11b in accordance with the decrease amount of the lubricant A without manually adjusting the hydraulic pressure in the lubricant filling portion 7. Through this, the hydraulic pressure in the lubricant filling portion 7 can be constantly increased.

Other configurations and operations are the same as those in the third embodiment.

The present invention is not limited to the above-mentioned embodiment, and various design changes can be made. For example, the ball screw 1 shown in each of the above embodiments shows a type in which the balls 6, 6, ... Circulate, but the ball screw circulating device according to the present invention is a ball screw of a type in which the balls 6, 6 ,. , Or all or a part of the balls 6, 6, ... Or the screw shaft 2 itself is also applicable to a ball screw made of ceramics.

Further, as the pressurizing means 11, an automatic hydraulic control device (not shown) can be adopted.

[0036]

As described in detail above, according to the ball screw lubrication method and the lubrication apparatus of the present invention, the lubricant filled in the screw shaft causes the centrifugal force generated as the screw shaft rotates. With this configuration, the lubricant is directly and forcibly supplied to the ball raceway surface of the ball raceway portion through the lubricant supply hole extending in the radial direction of the screw shaft. It is possible to supply the lubricant only by the driving means of the screw.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of a ball screw provided with a ball screw circulating device according to the present invention, and showing only a nut body in section.

FIG. 2 is a front cross-sectional view of the ball screw, which is II in FIG.
-A sectional view taken along the line II.

FIG. 3 is a partially enlarged front sectional view showing a structure of a lubricant supply hole in the ball screw.

FIG. 4 is a front sectional view showing a second embodiment of the ball screw.

FIG. 5 is a front sectional view showing a third embodiment of the ball screw.

FIG. 6 is a front sectional view showing a fourth embodiment of the ball screw.

FIG. 7 is a front view in which only a nut body of a conventional ball screw is shown in section, and is a front view showing a method for supplying a lubricant.

[Explanation of symbols]

 1 Ball Screw 2 Screw Shaft 3 Spiral Groove (Ball Orbital Groove) 3a Bottom of Spiral Groove 4 Nut Body 5 Spiral Groove 6, 6, ... Ball 7 Lubricant Filling Portion 7a Inner Surface of Lubricant Filling Portion 7b Lubricant Filling Portion One end 7c of the other end of the lubricant filling part 8, 8, ... Lubricant supply hole 8a One end of the lubricant supply hole 8b The other end of the lubricant supply hole 8c Inner peripheral surface of the lubricant supply hole 10 Lubricant introduction part 11 Addition Pressure means 12 Blind plug A Lubricant L Moving stroke C Center of moving stroke

Claims (3)

[Claims] 1. A method applied to a ball screw in which a screw shaft is rotationally driven, wherein a lubricant is filled inside the screw shaft, and the lubricant is centrifugal force generated as the screw shaft rotates. The ball screw lubrication method is characterized in that the lubricant is supplied to the ball raceway portion through a lubricant supply hole extending in the radial direction of the screw shaft. 2. A device provided in a ball screw whose screw shaft is rotationally driven, wherein a lubricant filling portion is provided inside the screw shaft so as to extend in the axial direction of the screw shaft. A plurality of lubricant supply holes communicating with the
A ball screw lubrication device, characterized in that it extends in the radial direction of the screw shaft and is opened so as to face the bottom of the ball raceway groove. 3. The lubrication device for a ball screw according to claim 2, wherein the lubricant introducing portion provided at one end of the lubricant filling portion is provided with a pressurizing means for increasing a hydraulic pressure in the lubricant filling portion. .