JP2003269569A - Ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw capable of almost uniformly supplying oil to a plurality of places without providing many oil supplying holes in an axial direction. <P>SOLUTION: Either one or both of a screw shaft 2 and a nut 3 are provided with an oil supplying hole 11 extended along an axial direction in a screwing part which is the screw shaft 2 or the nut 3. A plurality of oil supplying holes 12 in a radial direction communicating with the oil supplying hole 11 in the axial direction and opened in a screw groove 5 are provided apart from each other in the axial direction. The internal diameters of the plurality of oil supplying holes 12 in the radial direction are set different from each other according to the positions in an axial direction so that the quantities of oil discharged from the oil supplying holes 12 in the radial direction are more equalized than when they are set equal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw used in industrial machines such as machine tools, injection molding machines, press machines, and automobiles, and more particularly to a structure for supplying oil, grease and the like.

[0002]

2. Description of the Related Art Conventionally, this type of ball screw has been lubricated from the inside of a member of a screw shaft or a nut, and pipes are provided up to the screw groove, which is the lubrication point. FIG. 18 shows a sectional view of an example thereof. This ball screw 41 is of a return tube type using a return tube 47 as a ball reversing part, and when the nut 43 side is rotated and used as shown by an arrow R, generally, an oil supply pipe 50 is provided as shown in FIG. Is installed on the side of the screw shaft 42 that moves forward and backward as indicated by arrow P. In this case, there is only one lubrication point, the lubrication hole 51 extending along the axial direction is provided in the axial center of the screw shaft 42, and the screw shaft 42 is communicated with the axial lubrication hole 51.
A radial oil supply hole 52 that opens into the thread groove 45 on the outer diameter surface of is formed. Refueling is performed from the opening end of the axial refueling hole 51 as shown by arrow Q.

When oil is supplied to two places of the screw groove 45 on the screw shaft 42 side, as shown in FIG. 19, separate axial direction oil supply holes 51 are formed for the respective oil supply positions, and each axial direction is supplied. Radial oil supply holes 52 are formed from the oil supply holes 51 to the target oil supply points. In this way, separate oil supply pipes 50
By installing, a certain amount of oil can be reliably supplied to each oil supply location.

In addition, as shown in FIG. 20, from one axial oil supply hole 51, a plurality of radial oil supply holes 52 communicating with this are provided as holes of the same diameter, and oil is supplied to a plurality of oil supply points respectively. You can think of something to do. In this case, the axial oil supply hole 5
Although the amount of oil supplied to the radial direction oil supply hole 52 near the start end of No. 1 increases, the radial direction oil supply hole 52 far from the start end of the axial direction oil supply hole 51
The amount of refueling is reduced. Therefore, if it is attempted to lubricate a plurality of locations so that the amount of lubrication is equalized, one axial oil supply hole 51 is required for one radial oil supply hole 52 as in the example of FIG. If there are n lubrication points, n axial lubrication holes 51 are required.

[0005]

However, if the individual axial lubrication holes 51 are formed by the number of lubrication points, not only a great deal of cost is required for machining the lubrication holes, but also the diameter dimension of the screw shaft 42. Since there is a limit to the number, it is difficult to provide a large number of axial oil supply holes 51.

An object of the present invention is to provide a ball screw which can supply oil to a plurality of locations substantially uniformly without providing a large number of oil supply holes in the axial direction.

[0007]

SUMMARY OF THE INVENTION A ball screw according to the present invention has a screw shaft having a thread groove on its outer diameter surface, and a screw groove loosely fitted on the outer periphery of the screw shaft and facing the screw groove on the inner diameter surface. A ball screw having a formed nut and a ball interposed between the screw shaft and the screw groove of the nut, wherein the screw shaft or the nut is provided on one or both of the screw shaft and the nut. An oil supply hole extending along the axial direction is provided inside the threaded component, and a plurality of radial oil supply holes communicating with the axial oil supply hole and opening in the screw groove are provided axially separated from each other. The inner diameters of the plurality of radial oil supply holes are made different from each other in accordance with the axial position so that the amount of oil discharged from each radial oil supply hole is equalized as compared with the case where the diameters are all the same. . The radial oil supply hole and the screwing component provided with the radial oil supply hole may be only the screw shaft, only the nut, or both the screw shaft and the nut. It should be noted that the refueling referred to in this specification includes the meaning of refueling supplying grease, in addition to the oil supply in the narrow sense of supplying oil. According to this configuration, since the radial oil supply holes are provided at a plurality of positions apart from each other in the axial direction and the inner diameters of the radial oil supply holes are made different from each other, it is possible to supply the oil to the plurality of positions substantially uniformly and to perform stable oil supply. . Further, the above-mentioned uniform oil supply can be performed without providing a large number of oil supply holes in the axial direction inside the screw shaft and the screwed parts of the nut. When the above-mentioned relationship of the inner diameter of the radial direction oil supply hole is adopted for the screw shaft, poor lubrication does not occur at any position within the ball screw nut stroke range, and stable rotation of the ball screw due to poor lubrication does not occur. Can be prevented. A structure in which the inner diameters of the plurality of radial oil supply holes are made different from each other in accordance with the axial position so that the amount of oil discharged from each radial oil supply hole is made more uniform than in the case where the diameters are all the same. For example, when the lubricant is supplied to the axial oil supply hole from one direction, the inner diameter of the radial oil supply hole may be increased as the lubricating oil flows to the lower side.

In the present invention, the axial oil supply holes may be supplied with the lubricant from both sides in the axial direction. If the oil is supplied from both directions, the oil supply capacity is improved. In this case, the inner diameter of the radial oil supply hole may be increased toward the central side in the axial direction.

In the present invention, a plurality of the above-mentioned axial oil supply holes are provided in the same threaded component, and with respect to each axial oil supply hole, a radial direction communicating with this axial oil supply hole and opening in the thread groove is provided. A plurality of oil supply holes are provided so as to be axially separated from each other, and for radial oil supply holes communicating with at least one axial oil supply hole, the inner diameters of the radial oil supply holes are all the same as each other. Also, they may be different from each other depending on the axial position so that the amount of oil discharged from each radial oil supply hole is equalized. For all the axial oil supply holes, the inner diameters of the radial oil supply holes communicating with the axial oil supply holes may be different from each other as described above. With this structure, a plurality of axial oil supply holes are provided in the same screw component within the range allowed by the dimensions of the screw component, so that the number of oil supply outlets is increased, and uniform oil supply can be further improved. The radial oil supply holes of the individual axial oil supply holes have different inner diameters and are made uniform, so that the number of axial oil supply holes can be suppressed as much as possible while increasing the oil supply outlets. Therefore, the oil supply hole can be easily processed, and the problem of the strength reduction of the screwed component can be avoided.

In the present invention, the radial oil supply hole may be formed by an inner diameter hole of a tubular part fitted into the radial hole formed in the screwed part. When the tubular component is used in this way, it is possible to easily perform processing for making the diameter of the radial oil supply hole different depending on the axial position.

Further, in the present invention, the ball reversing path provided in the nut is connected to the rolling path formed between the screw shaft and the thread groove of the nut, so that a series of balls are circulated. It is also possible to provide a plurality of ball circulation passages, provide the nuts with the axial oil supply holes and the radial oil supply holes communicating with the axial oil supply holes, and open the radial oil supply holes in the thread grooves of each series of ball circulation paths. In the case where a plurality of series of ball circulation paths are provided in this way, stable lubrication can be performed in any of the ball circulation paths by setting the relationship of the inner diameters of the radial oil supply holes of the present invention. Becomes poor lubrication, and it becomes possible to prevent the ball screw from being unable to rotate due to poor lubrication caused by the ball circulation path. That is, when the nut is provided with the radial direction oil supply hole, the conventional oil supply structure causes uneven circulation in some ball circulation paths, which may cause rotation failure. It can be lubricated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. As shown in the longitudinal sectional view in FIG.
The ball screw 1 is of a return tube type and includes a screw shaft 2, a nut 3 loosely fitted to the outer periphery of the screw shaft 2, and a plurality of balls 4, and the nut 3 serves as a ball reversing path. The return tube 7 is attached. The screw shaft 2 has a spiral thread groove 5 on its outer diameter surface. The nut 3 has a thread groove 6 that faces the thread groove 5 of the screw shaft 2 on its inner diameter surface. The plurality of balls 4 are accommodated in series in a spiral rolling path 8 formed between the screw grooves 5 and 6 of the screw shaft 2 and the nut 3. This rolling road 8
As shown in FIG. 3 which is a perspective view, a series of ball circulation paths 15 are formed by connecting the return tube 7. Two return tubes 7 are provided, and two series of ball circulation paths 15 are formed.

In the ball screw 1, the nut 3 is rotated as shown by an arrow R to move the screw shaft 2 forward and backward as shown by an arrow P. Of the screw shaft 2 and the nut 3 which are screwed parts, inside the screw shaft 2 which is the advancing / retreating member, oil supply passages 10 for supplying oil to a plurality of positions of the screw groove 5 of the screw shaft 2 are formed. . The oil supply passage 10 has one oil supply hole 11 extending in the axial direction inside the screw shaft 2, and a plurality of oil supply holes 11 communicating with the axial oil supply hole 11 and extending in the radial direction to open in the screw groove 5 (here 7). The axial oil supply hole 11 has one end as a starting end that opens at one end of the screw shaft 2 and the other end as a closed end, and oil is supplied from the starting end as indicated by arrow Q. Also, a plurality of radial oil supply holes 1
2 are provided axially separated from each other, and these oil supply holes 1
The inner diameters of 2 are made different from each other in accordance with the axial position so that the amount of oil discharged from each oil supply hole 12 is made more uniform than in the case where all of them have the same diameter. The oil supply passage 10
Lubricating oil or grease is used as the lubricant supplied by.

FIG. 2 shows the plurality of oil supply holes 12 in the radial direction.
3 is a vertical cross-sectional view of the screw shaft 2 shown for distinguishing the hole positions of FIG. In the figure, the hole position of the radial oil supply hole 12 closest to the end of the axial oil supply hole 11 is No. No. 1 is set so that the number increases thereafter toward the starting end of the oil supply hole 11. 2 to No. It is numbered 7.

In order to compare the ball screw 1 of this embodiment with the oil supply performance, FIG. 4 shows the case where the diameters of the respective oil supply holes 12 in the radial direction in FIG. The amount of discharged oil is shown in a graph. The "type 1" shown in FIG. 4 (A) and the "type 2" shown in FIG. 4 (B) have different hole diameters. That is, as shown in Table 1, in “Type 1”, all the diameters of the respective oil supply holes 12 in the radial direction are 4 mmφ, and in “Type 2”, all the diameters of each oil supply hole 12 are 2.5 mmφ. Further, “Type 3” shown in the table is an example of the hole diameter of each oil supply hole 12 in the radial direction in the ball screw 1 of this embodiment, and “Type 4” is another example.

[0016]

[Table 1]

As shown in FIG. 4A, in the case of "Type 1" in which the diameters of all the oil supply holes 12 in the radial direction are 4 mmφ, the positions of the radial oil supply holes 12 are the axial oil supply holes 11. Although the amount of oil discharged from the radial oil supply hole 12 is large near the start end of
The amount of discharged oil decreases as the distance from the starting end of the axial oil supply hole 11 increases. In this case, the hole position No. near the end of the axial oil supply hole 11 from the intermediate position. 4 to No. In the case of 7, the ink is hardly discharged.

Further, as shown in FIG. 4 (B), in the case of "type 2" in which the diameters of all the oil supply holes 12 in the radial direction are 2.5 mmφ, the diameter is larger than that in the case of "type 1". Although there is the amount of oil discharged from each oil supply hole 12 in the direction, compared to the radial oil supply hole 12 at the hole position near the starting end of the axial oil supply hole 11,
The tendency that the amount of oil discharged from the radial direction oil supply hole 12 decreases as the hole position approaches the end of the axial direction oil supply hole 11 is not improved.

On the other hand, in the case of the "type 3" which is an example of the ball screw 1 of this embodiment, as shown in FIG. 5A, the discharge from the radial direction oil supply hole 12 is performed over all the hole positions. The amount of oil is equalized as compared with the comparative example. However, in this example, since the hole diameter of the radial direction oil supply hole 12 is gradually increased as the hole position approaches the end from the start end of the axial direction oil supply hole 11, on the contrary, it is close to the start end of the axial direction oil supply hole 11. In the radial direction oil supply hole 12 at the hole position, the amount of discharged oil is small.

Further, in the case of "Type 4" which is another example of the ball screw 1 of this embodiment, the radial oil supply hole 12 is provided.
Since the hole diameter is the same from the start end to the intermediate position of the axial direction oil supply hole 11 and is gradually increased from the intermediate position to the end position, the hole position is axially different from that of "Type 3". The amount of discharged oil does not decrease near the starting end of the oil supply hole 11, and as shown in FIG. 5B, the amount of discharged oil is substantially equal at all hole positions.

As described above, the ball screw 1 of this embodiment
With this, it is possible to supply oil to a plurality of locations of the thread groove 5 substantially uniformly without providing a large number of axial oil supply holes 11. Also,
Since the screw shaft 2 of the ball screw 1 adopts the above-mentioned relation of the inner diameter of the radial oil supply hole 12, the lubrication does not occur at any position within the nut stroke range of the ball screw 1, and the ball screw 1 is not lubricated due to the lubrication defect. The failure of stable rotation can be prevented.

FIG. 6 shows another embodiment of the present invention.
In this ball screw 1, by rotating the screw shaft 2 as shown by an arrow R, the nut 3 is used to move forward and backward as shown by an arrow P. Of the screw shaft 2 and the nut 3 which are screwed parts, An oil supply passage 20 for supplying oil to a plurality of positions of the thread groove 6 of the nut 3 is formed inside the nut 3 that serves as the advancing / retreating member. The oil supply passage 20 includes a single oil supply hole 21 extending in the nut 3 along the axial direction.
The nut 3 communicating with the axial oil supply hole 21 and extending in the radial direction
And a plurality of (four in this case) oil supply holes 22 that open to the thread groove 6 of FIG. One end of the axial oil supply hole 21 is a starting end that opens at one end of the nut 3 and the other end is a closed end, and oil is supplied from the starting end as indicated by arrow Q. In addition, a plurality of oil supply holes 22 in the radial direction
Are provided so as to be separated from each other in the axial direction, and the inner diameters of these radial direction oil supply holes 22 are smaller than those of the case where all of them have the same diameter.
In order to equalize the amount of oil discharged from the two, they are made different from each other depending on the position in the axial direction. Two return tubes 7 are provided, and two series of ball circulation paths 15 are provided. Other configurations are the same as those of the first embodiment shown in FIGS.

Also in the case of this embodiment, the axial oil supply hole 21 is provided.
It is possible to uniformly supply oil to a plurality of positions of the thread groove 6 via the oil supply passage 20 inside the nut 3 without providing a large number of parts. In the case where the nut 3 is provided with the oil supply passage, if there are a plurality of ball circulation passages, the conventional oil supply structure tends to cause non-uniform circulation, but this embodiment enables stable lubrication by uniform supply of lubricating oil. That is, in this embodiment,
Guided lubrication can be performed in any ball circulation path 15,
It becomes possible to prevent the ball screw 15 from rotating unsuccessfully due to poor lubrication caused by some of the ball circulation paths 15.

FIG. 7 shows still another embodiment of the present invention. In this ball screw 1, an oil supply passage 10 having the same configuration as that of the first embodiment is formed inside the screw shaft 2, and
Inside the nut 3, the oil supply passage 2 having the same configuration as that of the embodiment of FIG.
0 is formed. The oil supply passage 10 inside the screw shaft 2
It is composed of one axial oil supply hole 11 and a plurality of radial oil supply holes 12 communicating with the axial oil supply hole 11.
This is the same as in the first embodiment. In addition, the oil supply passage 20 inside the nut 3 includes one axial oil supply hole 21 and a plurality of radial oil supply holes 22 communicating with the axial oil supply hole 21. It is the same as the form. Other configurations are the same as those in the first embodiment. In addition, in the case of the ball screw 1, the nut 3 may be used in a state of being a rotation side member or the screw shaft 2 may be used in a state of being a rotation side member.

Also in this embodiment, without providing a large number of axial oil supply holes 11 and 21 inside the screw shaft 2 and the nut 3,
Oil can be evenly supplied to a plurality of locations of the thread groove 5 of the screw shaft 2 and the thread groove 6 of the nut 3. Particularly, in this embodiment, not only the oil supply passage 10 inside the screw shaft 2 can uniformly supply oil to a plurality of locations of the screw groove 5 of the screw shaft 2, but also the oil supply passage 20 inside the nut 3 can provide the screw groove 6 of the nut 3. Since the oil can be evenly supplied to a plurality of places, the oil supply function can be further enhanced.

FIG. 8 shows still another embodiment of the present invention. In this ball screw 1, the first screw shown in FIGS.
In the ball screw 1 of this embodiment, the axial oil supply holes 11 forming the oil supply passage 10 inside the screw shaft 2 are opened at both ends of the screw shaft 2 so that the lubricant is supplied from both sides in the axial direction. I have to. In the case of this embodiment, for the hole diameter of the radial direction oil supply hole 12, for example, at the hole position from one end of the axial direction oil supply hole 11 to the intermediate position, the hole diameter is sequentially increased in the order of position, and the axial direction oil supply hole 12 is increased. Also in the hole positions from the other end of 11 to the intermediate position, the hole diameter is increased in order of the position, so that the hole diameter is changed according to the arrangement position in the axial direction. This makes it possible to equalize the amount of oil discharged from the radial oil supply hole 12 at each hole position.
Other configurations are the same as those in the first embodiment. In the case of this embodiment, since the lubricant can be supplied from both sides of the axial oil supply hole 11, the oil supply function can be further enhanced.

FIG. 9 shows still another embodiment of the ball screw of the present invention. In this ball screw 1, in the ball screw 1 of the embodiment shown in FIG. 6, an axial oil supply hole 21 that constitutes an oil supply passage 20 inside the nut 3 is provided in the nut 3.
The lubricant is supplied from both sides in the axial direction by opening at both ends. Also in the case of this embodiment, for the hole diameter of the radial oil supply hole 22, for example, in the hole position from one end of the axial oil supply hole 21 to the intermediate position, the hole diameter is gradually increased in the order of position, and the axial direction is increased. The hole diameters of the oil supply holes 21 from the other end to the intermediate position are also made different in accordance with the axial arrangement position such that the hole diameters are sequentially increased in the order of position. This makes it possible to equalize the amount of oil discharged from the radial oil supply hole 22 at each hole position. Other configurations are the same as those of the embodiment of FIG.

FIG. 10 shows still another embodiment of the present invention. In this ball screw 1, in the ball screw 1 of the embodiment shown in FIG. 7, the oil supply passage 10 inside the screw shaft 2 is provided.
Axial oil supply holes 11 constituting the above are opened at both ends of the screw shaft 2 so that the lubricant is supplied from both sides in the axial direction, and an oil supply passage 20 inside the nut 3 is formed. The holes 21 are also opened at both ends of the nut 3 so that the lubricant can be supplied from both sides in the axial direction. Also in the case of this embodiment, for the hole diameters of the radial direction oil supply holes 12 and 22, for example, at the hole positions from one end of the axial direction oil supply holes 11 and 21 to the intermediate position, the hole diameters are sequentially increased in that order. The hole diameters of the axial direction oil supply holes 11 and 21 from the other end to the intermediate position are also increased in the order of their positions, such that the hole diameters are changed according to the axial arrangement position. There is. This makes it possible to equalize the amount of oil discharged from the radial oil supply holes 12 and 22 at each hole position. The other structure is the same as that of the embodiment of FIG.

FIG. 11 shows still another embodiment of the present invention. In this ball screw 1, in the ball screw 1 of the first embodiment shown in FIGS. 1 to 5, two oil supply passages 10 inside the screw shaft 2 are provided. Each oil supply channel 10
There is one axial oil supply hole 11 and this axial oil supply hole 1
It is the same as the first embodiment in that it is composed of a plurality of radial oil supply holes 12 communicating with 1.

In this embodiment, two oil supply passages 10 provided inside the screw shaft 2 are used to supply oil to a plurality of positions in the thread groove 5 of the screw shaft 2, so that the oil supply path is increased and uniform oil supply is further improved. Can be improved. Also, the axial oil supply hole 1
Since the number of screws 1 is as small as two, the oil supply passage 10 can be easily processed without being restricted by the dimensions of the screw shaft 2.

FIG. 12 shows still another embodiment of the present invention. This ball screw 1 is the same as the ball screw 1 of the embodiment shown in FIG. 6, except that two oil supply passages 20 inside the nut 3 are provided. It is the same as the embodiment of FIG. 6 that each oil supply passage 20 is composed of one axial oil supply hole 21 and a plurality of radial oil supply holes 22 communicating with the axial oil supply hole 21.

Also in this embodiment, the two oil supply passages 20 provided inside the nut 3 supply oil to a plurality of locations of the thread groove 6 of the nut 3, so that uniform oil supply can be further improved. Also, since the number of axial oil supply holes 21 is as small as two,
The oil supply passage 2 can be easily carried out without being restricted by the dimensions of the nut 3.
Processing of 0 can be performed.

FIG. 13 shows still another embodiment of the present invention. This ball screw 1 is the same as the ball screw 1 of the embodiment shown in FIG. 7, except that two oil supply passages 10 inside the screw shaft 2 are provided and two oil supply passages 20 inside the nut 3 are also provided. . Each oil supply passage 10 of the screw shaft 2 includes one axial oil supply hole 21 and a plurality of radial oil supply holes 12 communicating with the axial oil supply hole 11, and each oil supply passage of the nut 3. 20 is a single oil supply hole 21 in the axial direction
And a plurality of radial oil supply holes 22 communicating with the axial oil supply hole 21 are the same as in the embodiment of FIG. 7.

In this embodiment, not only can the two oil supply passages 10 inside the screw shaft 2 be used to evenly supply oil to a plurality of locations on the thread groove 5 of the screw shaft 2, but also the two oil supply passages 20 inside the nut 3 can be provided. By this, it is possible to evenly supply oil to a plurality of locations of the thread groove 6 of the nut 3. Therefore, the uniform oil supply can be further improved, and the oil supply function can be further improved. Further, since the number of the axial oil supply holes 11 and 21 in the screw shaft 2 and the nut 3 is as small as two, the size of the screw shaft 2 and the nut 3 is not limited, and the oil supply passage 1 can be easily provided.
Processing of 0 and 20 can be performed.

As shown in FIG. 14, the radial oil supply holes 12 and 22 in each of the above-described embodiments have a cylindrical part 31 in the radial hole 30 formed in the screw shaft 2 or the nut 3 which is a threaded part. May be fitted to each other and formed by the inner diameter of the tubular part 31. The tubular part 31 is made of gun metal, for example. By forming the radial direction oil supply holes 12 and 22 in this manner, it is possible to easily perform a process of making the hole diameter different depending on the axial position. That is, all of the radial holes 30 are formed identically, and the inner diameters of the tubular parts 31 fitted in the radial holes 30 are made different from each other.
A plurality of radial oil supply holes 12 and 22 having different hole diameters can be easily formed.

Further, in each of the above-mentioned embodiments, the case of the return tube type ball screw 1 has been shown, but the present invention is not limited to this, and as shown in FIG. 15, the ball reversing portion provided in the nut 3 is a circulation piece called a piece. The top type ball screw 1A configured by the component 27 may be used. Further, as shown in FIG. 16, the ball reversing portion provided on the nut 3 may be applied to the guide plate type ball screw 1B constituted by the guide groove 37 of the guide plate 36 provided on the nut 3. Further, as shown in FIG. 17, the ball reversing portion provided on the nut 3 is provided at the end cap 3 provided at the end portion of the nut 3.
End cap type ball screw 1C formed by the guide groove 39 of 8 and the nut through hole 40 penetrating the inside of the nut 3.
Can be applied to. Also in each of these types of ball screws, the same effects as described above can be obtained.

[0037]

According to the ball screw of the present invention, one or both of the screw shaft and the nut are provided with an oil supply hole extending in the axial direction inside the threaded component which is the screw shaft or the nut. Than the case where a plurality of radial oil supply holes communicating with the horizontal oil supply holes and opening to the screw groove are provided axially separated from each other, and the inner diameters of the plurality of radial oil supply holes are all the same. Since the amount of oil discharged from each radial direction oil supply hole is made different depending on the axial position, it is possible to supply oil to a plurality of locations substantially evenly without providing multiple axial oil supply holes. It can be carried out. Therefore, stable refueling becomes possible. When the above-mentioned relation of the inner diameter of the radial oil supply hole is adopted for the screw shaft of the ball screw,
It is possible to prevent defective rotation of the ball screw due to poor lubrication without causing poor lubrication at any position within the nut stroke range of the ball screw. Further, when the above-mentioned relationship of the inner diameter of the radial oil supply hole is adopted for the nut and the radial oil supply hole is opened in each of the plurality of ball circulation paths provided, guided lubrication can be performed in any ball circulation path. Therefore, it is possible to prevent a part of the ball circulation path from being poorly lubricated and prevent the ball screw from rotating poorly due to the poor lubrication caused by the ball circulation path.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a ball screw according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a screw shaft of the ball screw.

FIG. 3 is a perspective view showing a part of the ball screw in a cutaway manner.

FIGS. 4A and 4B are graphs showing the amount of oil discharged from the radial oil supply holes of each comparative example in which the diameters of all the radial oil supply holes in the ball screw are the same.

5A and 5B are graphs showing the amount of oil discharged from a radial oil supply hole of each example of the ball screw.

FIG. 6 is a vertical sectional view of a ball screw according to another embodiment of the present invention.

FIG. 7 is a vertical cross-sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 9 is a vertical sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 10 is a longitudinal sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 11 is a vertical cross-sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 12 is a vertical cross-sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 13 is a vertical cross-sectional view of a ball screw according to still another embodiment of the present invention.

FIG. 14 is an enlarged sectional view of an essential part showing a modified example of the radial oil supply hole in each of the embodiments.

FIG. 15 is a perspective view showing a top type ball screw.

FIG. 16 is a cross-sectional view showing a guide plate type ball screw.

FIG. 17 is a cross-sectional view showing an end cap type ball screw.

FIG. 18 is a vertical sectional view showing a conventional example.

FIG. 19 is a vertical sectional view showing another conventional example.

FIG. 20 is a vertical sectional view showing still another conventional example.

[Explanation of symbols] 1, 1A, 1B ... Ball screw 2 ... Screw shaft (threaded parts) 3 ... Nut (threaded part) 4 ... ball 5 ... Screw shaft thread groove 6 ... Nut thread groove 15 ... Ball circuit 11, 21 ... Axial oil supply hole 12, 22 ... Radial oil supply hole 30 ... Radial hole 31 ... Cylindrical parts

Continued front page    F term (reference) 3J062 AA02 AA21 AA25 AB22 AC07                       BA27 CD04 CD22 CD32 CD45                       CD75

Claims (5)

[Claims] 1. A screw shaft having a thread groove on its outer diameter surface, a nut which is loosely fitted on the outer circumference of the screw shaft, and has a thread groove facing the screw groove formed on the inner diameter surface, and the screw shaft and the nut. In a ball screw having a ball interposed between the screw grooves of, one or both of the screw shaft and the nut,
An oil supply hole extending along the axial direction is provided inside the threaded part that is the screw shaft or the nut, and radial oil supply holes communicating with the axial oil supply hole and opening in the screw groove are provided in the axial direction. A plurality of separate oil supply holes are provided separately from each other in the axial direction so that the amount of oil discharged from each radial oil supply hole is more equalized than in the case where the inner diameters of the plurality of radial oil supply holes are all the same. Ball screw characterized by being different from each other. 2. The ball screw according to claim 1, wherein the lubricant is supplied to the axial oil supply holes from both sides in the axial direction. 3. A plurality of the axial oil supply holes are provided in the same threaded component, and for each axial oil supply hole, a radial oil supply hole communicating with the axial oil supply hole and opening in a thread groove is formed. , The radial direction oil supply holes which are provided in a plurality apart from each other in the axial direction and communicate with at least one axial direction oil supply hole, than the case where the inner diameters of the radial direction oil supply holes are all the same diameter The ball screw according to claim 1 or 2, wherein the amounts of oil discharged from the oil supply holes are made different from each other depending on the axial position. 4. The oil supply hole in the radial direction is formed by an inner diameter hole of a tubular part that fits into a radial hole formed in the screwed part. Ball screw. 5. A series of ball circulation paths configured to circulate balls by connecting a ball reversal path provided on a nut to a rolling path formed between a screw shaft and a thread groove of a nut. 5. A plurality of axial lubrication holes and radial lubrication holes communicating with the axial lubrication holes are provided in the nut, and the radial lubrication holes are opened in the thread grooves in each series of ball circulation paths. Ball screw according to any one.