JP2006038004A - Ball screw device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for supplying lubricant to a ball screw device while preventing vibration. <P>SOLUTION: The ball screw device comprises a screw shaft having a spiral shaft raceway groove in the outer peripheral face and a nut having a nut raceway groove in the inner peripheral face in opposition to the shaft raceway groove, the shaft raceway groove and the nut raceway groove being threaded together via a ball. A dummy groove is formed in parallel to the shaft raceway groove, and a pipe is wound on the dummy groove. The opening at the end of the wound pipe is located at the approximate center of the screw shaft to form a lubricant discharge port. Thus, the pipe is functioned as a lubricant supply passage for supplying lubricant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ball screw device used for a feed mechanism of a moving body of a machine device such as a machine tool, a precision machine, or a semiconductor manufacturing device.

  In the conventional ball screw device, a shaft raceway groove formed in a spiral shape on the outer peripheral surface of a screw shaft and a nut raceway groove opposed to the shaft raceway groove formed on an inner peripheral surface of a nut are screwed together via a plurality of balls. A plurality of radial oil supply holes that communicate with the axial oil supply holes formed along the axis of the screw shaft and open to the shaft raceway grooves, and the inner diameters of these oil supply holes are positioned in the axial direction. Accordingly, the lubricant is supplied to the ball screw device by equalizing the amount of oil to be discharged (see, for example, Patent Document 1).

In addition, when the ball screw device has a long screw shaft, a long center shaft is inserted into a hollow hole formed along the axis of the screw shaft, and a plurality of bushes are provided between the inner shaft and the inner diameter of the hollow hole. It is provided to attenuate the vibration in the resonance state of the long screw shaft (see, for example, Patent Document 2).
JP 2003-269569 A (3rd page, paragraph 0012-paragraph 0013, FIG. 1) Japanese Patent No. 2979952 (page 3, paragraphs 0013-0021, FIG. 1)

However, in the technique of Patent Document 1 described above, since the lubricating oil is supplied by providing a radial oil supply hole that opens to the shaft raceway groove, the opening of the oil supply hole to the shaft raceway groove becomes a step, and the shaft There is a problem that when a ball rolling between the raceway groove and the nut raceway groove passes through the oil supply hole, it may drop into the oil supply hole and generate vibration.
Further, in the configuration in which the lubricant is supplied through the axial oil supply hole formed along the axial center of the screw shaft, when the vibration damping structure is provided in the hollow hole provided in the screw shaft as in Patent Document 2, lubrication is performed. There is a problem that oil cannot be supplied.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide means for supplying a lubricant to a ball screw device while preventing the occurrence of vibration.

  In order to solve the above problems, the present invention has a screw shaft in which a spiral shaft raceway groove is formed on the outer peripheral surface, and a nut in which a nut raceway groove facing the shaft raceway groove is formed on the inner peripheral surface. In the ball screw device in which the shaft raceway groove and the nut raceway groove are screwed together via a plurality of balls, a dummy groove is formed in parallel with the shaft raceway groove, and a pipe is wound around the dummy groove. The end portion of the pipe is opened in the dummy groove to serve as a lubricant discharge port, and the pipe is used as a lubricant supply path for supplying the lubricant.

As a result, the present invention can supply the lubricant to the ball screw device from the dummy groove provided in parallel with the shaft raceway groove, thereby preventing the occurrence of vibration and obtaining a quiet ball screw device. Is obtained.
Further, the lubricant can be supplied to the ball screw device without providing the axial oil supply hole along the axis of the screw shaft, and the lubricant is also supplied to the ball screw device having the vibration damping structure on the screw shaft. The effect that it can be obtained.

  Embodiments of a ball screw device according to the present invention will be described below with reference to the drawings.

1 is a cross-sectional view showing a ball screw device according to a first embodiment, FIG. 2 is an enlarged view showing a side surface of a screw shaft according to the first embodiment, and FIG. 3 is an explanatory view showing a lubricant supply system according to the first embodiment.
In FIG. 1, reference numeral 1 denotes a ball screw device, and in this embodiment, an end cap type ball screw device.
Reference numeral 2 denotes a screw shaft of the ball screw device 1, which is a rod-shaped member made of a steel material such as alloy steel. A single shaft raceway groove 3 having a substantially semicircular cross-sectional shape is formed on the outer peripheral surface of the rod-shaped member. In addition, the spiral 1 is formed in a spiral shape at a predetermined pitch, and is screwed with a coiled pipe 13 to be described later in parallel with the same lead as the axial track groove 3 between the pitches of the axial track groove 3. A strip dummy groove 4 is formed. Since the shaft raceway groove 3 of the screw shaft 2 of this embodiment is a single thread, the lead and pitch coincide with each other.

The cross-sectional shape of the dummy groove 4 of the present embodiment is formed in a substantially semicircular arc shape similar to that of the shaft raceway groove 3, and is externally the same shape as that of the screw shaft 2 in which the two shaft raceway grooves 3 are formed. It has become.
Reference numeral 5 denotes a nut of the ball screw device 1, which is a cylindrical member made of a steel material such as alloy steel, and has a substantially semicircular arc cross-sectional shape that faces the shaft raceway groove 3 on its inner peripheral surface. 6 is formed of the same lead as the shaft raceway groove 3.

The nut 5 is provided with a return path 7 that passes through the nut 5 in the axial direction.
Reference numeral 8 denotes an end cap, which is made of a metal material, a resin material, or the like, and is disposed at both ends of the nut 5 in the axial direction. A curved path connecting the return path 7 and the nut raceway groove 6 to each nut 5 side. A direction change path 9 is provided.
Reference numeral 10 denotes a ball, which is a sphere made of a steel material such as an alloy steel or a ceramic material, and rolls between the shaft raceway groove 3 and the nut raceway groove 6 to screw the screw shaft 2 and the nut 5 together. .

Reference numeral 11 denotes a flange portion which is provided on the outer peripheral portion of the nut 5 and is provided with a stepped bolt hole 12 for fixing.
Reference numeral 13 denotes a pipe, which is formed by winding a pipe having an outer diameter substantially equal to the depth of the dummy groove 4 of the screw shaft 2 made of a metal material or a resin material, as shown in FIG. When the screw-shaped member is screwed into the dummy groove 4, an opening (referred to as a lubricant discharge port 14) at the end of the pipe 13 is formed in the dummy groove 4 at a substantially central portion in the axial direction of the screw shaft 2. It is arranged to be located. As a result, the lubricant discharge port 14 is opened in the dummy groove 4, and a lubricant supply path for the lubricant to the ball screw device 1 of the present embodiment is formed by the pipe 13.

In addition, the installation of the coiled pipe 13 is performed by screwing the pipe 13 formed in a coil shape with the inner diameter of the coil slightly smaller than the valley diameter of the dummy groove 4 into the dummy groove 4 using its elasticity. It may be installed, or after being wound around the dummy groove 4, it may be installed partially or entirely with an adhesive or the like.
Further, the opening position of the lubricant discharge port 14 is not limited to the substantially central portion of the screw shaft 2 and may be opened anywhere within the movement range of the nut 5.

The return path 7 provided in the nut 5 and the direction changing path 9 provided in the end cap constitute the connection path of the present embodiment, and the shaft raceway groove 3 of the screw shaft 2 and the nut raceway groove of the nut 5 facing this. A circulation path through which the ball 10 circulates is formed by 6 and the connection path.
A plurality of balls 10 are enclosed in this circulation path, and the shaft raceway groove 3 and the nut raceway groove 6 are screwed together via the balls 10.

Further, a lubricant such as lubricating oil or grease is supplied to the pipe 13 screwed into the dummy groove 4 from the opening opposite to the lubricant discharge port 14, and the ball 10, the shaft raceway groove 3, the nut raceway groove 6, and the like. Lubricate between.
In FIG. 3, reference numeral 20 denotes a lubricant supply system of the ball screw device 1.
In the ball screw device 1 of the present embodiment, both ends of the screw shaft 2 are fixed in axial movement and rotation by a fixing plate 22 provided on a base 21 of a mechanical device (not shown), and the nut 5 rotates. The nut 5 itself reciprocates in the axial direction.

Reference numeral 23 denotes a moving table of the mechanical device, which is fixed to a slider 24b provided on the two rails 24a of a linear guide device 24 such as a linear guide device provided on the base 21 so as to be capable of linear reciprocation. .
Further, the moving table 23 is provided with a support plate 25, and rotatably supports the outer peripheral surface of the nut 5 via a rolling bearing (not shown).

Reference numeral 26 denotes a drive motor, which is fixed to a mounting bracket 27 provided on the moving base 23, and rotates a toothed pulley 28a attached to its rotating shaft in a reversible manner so as to be stepped on the flange portion 11 of the nut 5. The nut 5 is rotated in a reversible manner by an endless toothed belt 29 spanned between the toothed pulley 28b attached using the attached bolt hole 12.
A controller 30 of the lubricant supply system 20 rotates the drive motor 26 in a forward / reverse manner by a driver circuit (not shown), and nuts based on position information from a position detection unit such as an encoder (not shown) provided in the drive motor 26. 5 has a function of detecting a position on the screw shaft 2 and sending an oil supply command to the lubricant supply device 31.

The lubricant supply device 31 is connected to a supply pipe 32 connected to an opening on the opposite side of the lubricant discharge port 14 of the pipe 13 screwed into the dummy groove 4 of the screw shaft 2. Accordingly, the lubricant is supplied to the pipe 13 through the supply pipe 32.
In this case, if the lubricant is a liquid lubricant, a trochoid pump or gear pump is used to supply the lubricant. If a semi-solid grease is used, the piston pump or screw extruder pump is lubricated. Used to supply the agent.

Note that the lubricant discharge port 14 of this embodiment opens from the right fixing plate 22 in FIG. 3 to a substantially central portion on the left side by about 1/3 of the entire length of the screw shaft 2.
The operation of the above configuration will be described.
An operation in the case of lubricating between the ball 10 of the hall screw device 1 and the shaft raceway groove 3 and the nut raceway groove 6 using the lubricant supply system 20 will be described.

  When electric power is supplied from the controller 30 to the drive motor 26, the drive motor 26 rotates forward and the drive force is transmitted to the nut 5 via the toothed pulley 28a, the toothed belt 29, and the toothed pulley 28b. The nut 5 rotates and the nut 5 moves on the screw shaft 2 in the axial direction. The moving force of the nut 5 is transmitted to the moving table 23 guided by the linear motion guide device 24 via the support plate 25 and moved. The base 23 moves in the same direction as the nut 5.

At this time, the controller 30 monitors the position of the nut 5 while detecting the position of the nut 5 on the screw shaft 2 based on the position information from the drive motor 26, and the nut 5 is screwed into the dummy groove 4 of the screw shaft 2. The oil supply command is sent to the lubricant supply device 31 when passing through the position of the lubricant discharge port 14 of the pipe 13 to be performed.
Receiving the oil supply command, the lubricant supply device 31 activates a lubricant supply pump and pumps the lubricant to the pipe 13 through the supply pipe 32. The pumped lubricant is discharged from the lubricant discharge port 14 to the dummy groove 4.

In this case, if there is a time delay from the start of the pump to the discharge of the lubricant, the controller 30 may send an oiling command in advance in consideration of the delay, or the lubricant supply device 31. However, while always operating the pump, the bypass passage and the supply pipe 32 may be switched to supply the lubricant to the supply pipe 32 side.
The lubricant discharged to the dummy groove 4 enters between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 5 from the dummy groove 4, and the shaft raceway groove 3 and the nut 5 are rotated along with the rotation of the nut 5 due to the viscosity of the lubricant. The ball 10 that is carried to the nut raceway groove 6 and rolls there, lubricates between the shaft raceway groove 3 and the nut raceway groove 6.

The same applies to the case where the drive base 26 is rotated in the reverse direction and the movable table 23 guided by the linear motion guide device 24 is moved in the opposite direction.
As described above, if the lubricant is supplied in accordance with the passage of the lubricant discharge port of the nut, the lubricant can be supplied more effectively in the nut 5.
As described above, in this embodiment, the lubricant supply path is formed by the pipe spirally wound around the dummy groove provided in parallel with the shaft raceway groove of the screw shaft, so that it is provided in parallel with the shaft raceway groove. Lubricant can be supplied from the dummy groove to the ball screw device, and generation of vibration can be prevented and a quiet ball screw device can be obtained.

  Further, the lubricant can be supplied to the ball screw device without providing the axial oil supply hole along the axis of the screw shaft, and the lubricant is also supplied to the ball screw device having the vibration damping structure on the screw shaft. be able to.

FIG. 4 is an enlarged view illustrating a side surface of the screw shaft according to the second embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In the screw shaft 2 of the present embodiment, three dummy grooves 4 are formed in parallel with the shaft raceway groove 3 by dividing the pitch of the one shaft raceway groove 3 substantially equally. In addition, each dummy groove 4 is screwed with a coiled pipe 13 similar to that in the first embodiment, and each lubricant discharge port 14 is substantially in each dummy groove 4 in the substantially central portion of the screw shaft 2. It is installed so as to open at intervals of about 120 degrees in the circumferential direction on the cross section perpendicular to the axis. As a result, the lubricant discharge ports 14 are opened in the respective dummy grooves 4, and three lubricant supply paths for the lubricant to the ball screw device 1 of the present embodiment are formed by the pipes 13.

The operation of the above configuration will be described.
When the lubricant is supplied to the hole screw device 1 using the lubricant supply system 20, when power is supplied from the controller 30 to the drive motor 26 as in the first embodiment, the drive motor 26 rotates forward. The driving force is transmitted to the nut 5, the nut 5 rotates, and the moving table 23 guided by the linear motion guide device 24 moves in the same direction as the nut 5.

At this time, the controller 30 monitors the position of the nut 5 in the same manner as in the first embodiment, and the movement of the lubricant discharge port 14 of each pipe 13 where the nut 5 is screwed into each dummy groove 4 of the screw shaft 2. The oil supply command is sent to the lubricant supply device 31 when passing through the position of the lubricant discharge port 14 located on the most downstream side in the direction.
The lubricant supply device 31 that has received the oil supply command pumps the lubricant to each pipe 13 in the same manner as in the first embodiment. The pumped lubricant is discharged from each lubricant discharge port 14 to the dummy groove 4.

The lubricant discharged to each dummy groove 4 enters between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 5 from each dummy groove 4, and the shaft raceway groove as the nut 5 rotates due to the viscosity of the lubricant. 3 and the nut raceway groove 6 are lubricated between the ball 10 that rolls there and the shaft raceway groove 3 and the nut raceway groove 6.
The same applies to the case where the drive motor 26 rotates in the reverse direction to move the moving table 23 guided by the linear motion guide device 24 in the opposite direction.

Thus, if the lubricant is supplied from the three lubricant discharge ports 14 in accordance with the passage of the lubricant discharge port of the nut, the lubricant can be supplied more effectively in the nut 5.
As described above, in this embodiment, in addition to the same effects as in the first embodiment, three dummy grooves are provided in parallel with the shaft raceway groove of the screw shaft, and spirally wound around each dummy groove. By forming the lubricant supply path with the pipe, the lubricant can be supplied to the ball screw device more effectively from the three dummy grooves provided in parallel with the shaft raceway groove.

FIG. 5 is an enlarged view illustrating a side surface of the screw shaft according to the third embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In the screw shaft 2 of this embodiment, a single dummy groove 4 is formed in parallel with the shaft raceway groove in the same manner as in the first embodiment. Three dummy pipes 13 similar to those in the first embodiment are screwed into the dummy groove 4, and each lubricant discharge port 14 is substantially equal to the lead of the dummy groove 4 at the substantially central portion of the screw shaft 2. It is installed so as to open in the dummy groove 4 with an interval of. As a result, three lubricant discharge ports 14 are opened at intervals in one dummy groove 4, and three lubricant supply paths for the lubricant to the ball screw device 1 of this embodiment are formed by these pipes 13. It is formed.

In addition, the cross-sectional shape of the dummy groove | channel 4 is formed in the shape which has a big cross-sectional area compared with Example 1, for example, a semi-oval shape so that three pipes 13 similar to Example 1 can be installed.
The operation of the above configuration will be described.
When the lubricant is supplied to the hole screw device 1 using the lubricant supply system 20, when power is supplied from the controller 30 to the drive motor 26 as in the first embodiment, the drive motor 26 rotates forward. The driving force is transmitted to the nut 5, the nut 5 rotates, and the moving table 23 guided by the linear motion guide device 24 moves in the same direction as the nut 5.

At this time, the controller 30 monitors the position of the nut 5 as in the first embodiment, and the position of the lubricant outlet 14 of each pipe 13 where the nut 5 is screwed into each dummy groove 4 of the screw shaft 2. Is sent to the lubricant supply device 31 every time it passes through.
The lubricant supply device 31 that has received the oil supply command pumps the lubricant in order from the upstream side to the pipe 13 leading to the lubricant discharge port 14 in the same manner as in the first embodiment, and the lubricant thus pumped is the lubricant. The ink is discharged from the discharge port 14 to the dummy groove 4. As a result, the lubricant is sequentially discharged to each part of the single dummy groove 4. The lubricant discharged to the dummy groove 4 is sequentially between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 5 from the dummy groove 4. The nut 10 rotates and is carried to the shaft raceway groove 3 and the nut raceway groove 6 due to the viscosity of the lubricant. Lubricate.

The same applies to the case where the drive motor 26 rotates in the reverse direction to move the moving table 23 guided by the linear motion guide device 24 in the opposite direction.
In this way, if the lubricant is supplied in order from the three lubricant discharge ports 14 in accordance with the passage of the lubricant discharge port of the nut, the lubricant can be supplied into the nut 5 for a long time. And a better lubrication state can be achieved.

  As described above, in this embodiment, in addition to the same effects as in the first embodiment, a dummy groove is provided in parallel with the shaft raceway groove of the screw shaft, and the three pipes are spirally wound around the dummy groove. By forming the lubricant supply path, the lubricant can be sequentially supplied from the dummy groove provided in parallel with the shaft raceway groove as the nut passes, and the lubricant is supplied to the ball screw device for a long time. Can be supplied.

FIG. 6 is an enlarged view illustrating a side surface of the screw shaft according to the fourth embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In the screw shaft 2 of the present embodiment, three dummy grooves 4 are formed in parallel with the shaft raceway grooves, as in the second embodiment.
40 is a sealing tape as a covering material, which is a long tape made of a resin material, metal foil or the like, and adhesive is applied to the entire surface of one side or both edges of each side. A ball space is formed in a spiral space formed between each dummy groove 4 and the sealing tape 40 so that a film is formed by being attached so as to close the outer peripheral surface side of the screw shaft 2 of the dummy groove 4. It functions as three lubricant supply paths for the lubricant to 1.

Further, the lubricant outlet 14 of each lubricant supply passage is approximately 120 degrees in the circumferential direction on the cross section substantially perpendicular to the axis in each dummy groove 4 at the substantially central portion of the screw shaft 2 as in the second embodiment. It is installed to open at intervals.
The thickness of the sealing tape 40 is formed to be thinner than the gap formed between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 5.

Since the operation of the above configuration is the same as the operation of the second embodiment, the description thereof is omitted.
In this case, the supply pipe 32 and the lubricant supply path are connected by inserting the supply pipe 32 into the opening on the opposite side of the lubricant discharge port 14 of the lubricant supply path and supplying it using a sealing material or an adhesive. The tube 32 is fixed so as to communicate with the opening on the opposite side.

  As described above, in this embodiment, in addition to the same effects as those of the second embodiment, the dummy groove is covered with the sealing tape to form the lubricant supply path. The ball screw device can be easily lubricated without being used, and foreign matters can be prevented from entering the dummy grooves.

FIG. 7 is an enlarged view showing a side surface of the screw shaft of the fifth embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
The screw shaft 2 of the present embodiment has three dummy grooves 4 formed in the same manner as in the second embodiment, and a coiled pipe 13 is screwed into each of the dummy grooves 4. The respective dummy grooves 4 in the substantially central portion of the shaft 2 are installed so as to open at intervals of about 120 degrees in the circumferential direction on a substantially perpendicular section.

42 is a sealing material as a covering material, and the entire length except for the vicinity of the lubricant outlet 14 of each pipe 13 installed in each dummy groove 4 is buried to form a coating, and each pipe 13 is fixed to the dummy groove 4. is doing. A space formed by the inner diameter of the pipe 13 embedded with these coatings functions as three lubricant supply paths for the lubricant to the ball screw device 1 of this embodiment.
The outer diameter of the sealing material 42 is set so as to be substantially equal to the outer peripheral surface of the screw shaft 2.

Since the operation of the above configuration is the same as the operation of the second embodiment, the description thereof is omitted.
As described above, in this embodiment, in addition to the same effects as in the second embodiment, the pipe is covered with a sealing material and fixed, thereby preventing foreign matter from entering the dummy groove. In addition, the posture of the pipe can be stabilized.

FIG. 8 is an enlarged view illustrating a side surface of the screw shaft according to the sixth embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
Three shaft raceway grooves 3 are formed at a predetermined lead and a predetermined pitch on the screw shaft 2 of the present embodiment, and one dummy groove 4 is formed in parallel with the shaft raceway groove 3 with the same pitch. Is formed. A coil-like pipe 13 similar to that in the first embodiment is screwed into the dummy groove 4, and the lubricant discharge port 14 is installed so as to open into the dummy groove 4 in the substantially central portion of the screw shaft 2. ing. As a result, the lubricant discharge port 14 is opened in the dummy groove 4, and a lubricant supply path for the lubricant to the ball screw device 1 of the present embodiment is formed by the pipe 13.

Reference numeral 44 denotes a communication groove, which is a circumferential groove formed on the outer peripheral surface of the screw shaft 2 downstream of the lubricant discharge port 14 opened in the dummy groove 4. The drive groove 3 communicates in the circumferential direction.
The depth of the communication groove 44 is a depth at which the ball 10 does not reach the contact portion when rolling between the shaft raceway groove 3 and the nut raceway groove 6, that is, when the ball 10 rolls, the ball 10 does not reach the contact portion. The depth is set so that it does not fall into.

The operation of the above configuration will be described.
The operation of moving the moving table 23 and the operation of discharging the lubricant from the lubricant discharge port 14 to the dummy groove 4 when supplying the lubricant to the hall screw device 1 using the lubricant supply system 20 are described in the first embodiment. Since this is the same, the description thereof is omitted.
The lubricant discharged to the dummy groove 4 is connected to each shaft raceway groove 3 and the nut raceway from the dummy groove 4 along with the rotation of the nut 5 by the communication groove 44 formed on the outer peripheral surface of the screw shaft 2 due to the viscosity of the lubricant. Lubricated between the ball 10 that is carried to the groove 6 and rolls there, and the shaft raceway groove 3 and the nut raceway groove 6.

The same applies to the case where the drive motor 26 rotates in the reverse direction to move the moving table 23 guided by the linear motion guide device 24 in the opposite direction.
As described above, in this embodiment, in addition to the same effects as those of the first embodiment, a circumferential communication groove that connects the shaft raceway groove of the screw shaft and the dummy groove is provided downstream of the lubricant discharge port. By providing, the lubricant can be reliably supplied to the shaft raceway groove. This is particularly effective for lubrication of a ball screw device having a multi-axis shaft raceway groove.

FIG. 9 is an enlarged view illustrating a side surface of the screw shaft according to the seventh embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
The screw shaft 2 of the present embodiment is formed in the same manner as in the first embodiment, and a coiled pipe 13 similar to that in the first embodiment is screwed into the dummy groove 4, and the lubricant discharge port 14. Is installed so as to open in the dummy groove 4 at substantially the center of the screw shaft 2, and a pipe 13 forms a lubricant supply path for the lubricant to the ball screw device 1 of the present embodiment.

  46 is an intermediate discharge port, which is formed by piercing the pipe 13 in the radial direction between the lubricant discharge port 14 of the coiled pipe 13 screwed into the dummy groove 4 and the opening on the opposite side, or The opening area of the two or more holes is set so as to increase sequentially from the upstream side to the downstream side of the lubricant supply path, and the opening area of the lubricant discharge port 14 is set to be the maximum. In other words, the opening area of the lubricant discharge port 14 is maximized, and the opening area is reduced in order toward the upstream side of the lubricant supply path. The intermediate discharge ports 46 of this embodiment are formed so as to have the same interval as the leads of the dummy grooves 4.

The setting of the opening area of the intermediate discharge port 46 takes into consideration the pressure loss coefficient of the lubricant discharged from each intermediate discharge port 46 and the lubricant discharge port 14 and the contraction coefficient of the intermediate discharge port 46 and the lubricant discharge port 14. To set.
That is, the pressure loss coefficient due to the passage length through which the lubricant passes, the curvature of the pipe 13 and the difference in the bending length, the pressure loss coefficient due to the shape of the corner between the intermediate discharge port 46 and the inner peripheral surface of the pipe 13, etc. The pressure loss obtained from the above is subtracted from the original pressure to obtain the respective pressure differences from the atmospheric pressure at each of the intermediate discharge ports 46 and the lubricant discharge ports 14, taking into account the contraction coefficient due to the shape of the corners. Set so that the calculated flow rate is the same. Accordingly, the lubricant can be discharged from each intermediate discharge port 46 and the lubricant discharge port 14 substantially evenly.

The operation of the above configuration will be described.
When the lubricant is supplied to the hole screw device 1 using the lubricant supply system 20, when power is supplied from the controller 30 to the drive motor 26 as in the first embodiment, the drive motor 26 rotates forward. The driving force is transmitted to the nut 5, the nut 5 rotates, and the moving table 23 guided by the linear motion guide device 24 moves in the same direction as the nut 5.

In parallel with this, the controller 30 periodically sends a lubrication command to the lubricant supply device 31, and the lubricant supply device 31 that has received the lubrication command lubricates the pipe 13 through the supply pipe 32 in the same manner as in the first embodiment. The agent is pumped to discharge the lubricant from the intermediate discharge ports 46 and the lubricant discharge ports 14 to the dummy grooves 4.
The lubricant discharged from each intermediate discharge port 46 and the lubricant discharge port 14 to the dummy groove 4 enters between the outer peripheral surface of the screw shaft 2 and the inner peripheral surface of the nut 5 when the nut 5 passes through the portion. Due to the viscosity of the lubricant, as the nut 5 rotates, it is transported from the dummy groove 4 to the shaft raceway groove 3 and the nut raceway groove 6, and between the balls 10 rolling there and the shaft raceway groove 3 and the nut raceway groove 6. Lubricate.

The same applies to the case where the drive motor 26 rotates in the reverse direction to move the moving table 23 guided by the linear motion guide device 24 in the opposite direction.
As described above, in this embodiment, in addition to the same effects as in the first embodiment, the intermediate discharge port is provided in the middle of the lubricant supply path, so that the movement of the nut and the timing of discharge of the lubricant can be achieved. Even when it cannot be removed, the lubricant can be evenly supplied to the ball screw device.

In addition, the opening area of the lubricant discharge port is maximized, and the opening area of the intermediate discharge port is set so as to decrease in order toward the upstream side of the lubricant supply path. Lubricant can be discharged evenly.
In each of the examples except for the above-described Example 4, the cross-sectional shape of the dummy groove has been described as a substantially semicircular arc shape similar to that of the axial raceway groove. However, the depth of the dummy groove corresponds to the outer diameter of the coiled pipe. The shape is not limited to a circular arc, and may be a cross-sectional shape such as a square, trapezoid, or semi-ellipse. In short, any shape can be used as long as the coiled pipe can be screwed and the outer diameter of the coil is smaller than the inner diameter of the nut.

The cross-sectional shape of the fourth embodiment is not limited to the arc, but may be a square, trapezoid, semi-ellipse, or the like. In short, any shape may be used as long as the lubricant can be supplied without shortage.
In each of the above embodiments, the supply pipe and the lubricant supply path are directly connected. However, a jacket is provided at one end of the screw shaft, and the supply pipe and the lubricant supply path are provided via the jacket. May be connected.

In the above description, the case where the lubricant is supplied to the ball screw device 1 while preventing the occurrence of vibration has been described. However, it may be necessary to cool the screw shaft 2.
In this case, the pipe 13 of Examples 1 to 6 except for the above Example 4 is screwed into the dummy groove 4 over the entire length of the screw shaft 2, and the supply pipe 32 is connected to one end of the pipe 13. A cooling medium such as water or oil is pumped from the pump, a recovery pipe is connected to the other end, the cooling medium is recovered, and is recovered in a tank connected to the pump via a cooling device such as a chiller. .

As a result, the screw shaft 2 can be cooled with a simple configuration, and the positioning accuracy is improved by the thermal expansion of the screw shaft 2 due to heat generation when the nut 5 rotates at a high speed and the moving table 23 is moved at a high speed. Can be prevented from decreasing.
In the case of the fourth embodiment, the same effect can be obtained if the cooling medium is supplied to the lubricating oil supply passage in the same manner as described above.

In this case, when lubrication and cooling are used in combination, at least one of the pipes 13 shown in the second, third, and fifth embodiments is used as a cooling pipe in the same manner as described above, and the other pipes 13 are used for lubrication. What is necessary is just to use it as a pipe. The same applies to the fourth embodiment.
Further, in each of the above embodiments, the present invention is applied to a ball screw device using an end cap type circulation system in which a connecting path is formed by a return path provided on a nut and a direction change provided on an end cap to circulate a ball. Although the case where it is applied has been described as an example, the connection path is not limited to the above, and the same effect can be obtained even if the present invention is applied to a circulation type ball screw device in which the connection path is a top type, a return tube type, an end deflector type, etc. Can be obtained.

Sectional drawing which shows the ball screw apparatus of Example 1. The enlarged view which shows the side surface of the screw shaft of Example 1 Explanatory drawing which shows the lubricant supply system of Example 1. FIG. The enlarged view which shows the side surface of the screw shaft of Example 2. The enlarged view which shows the side surface of the screw shaft of Example 3 The enlarged view which shows the side surface of the screw shaft of Example 4. The enlarged view which shows the side surface of the screw shaft of Example 5. The enlarged view which shows the side surface of the screw shaft of Example 6. The enlarged view which shows the side surface of the screw shaft of Example 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball screw apparatus 2 Screw shaft 3 Shaft raceway groove 4 Dummy groove 5 Nut 6 Nut raceway groove 7 Return path 8 End cap 9 Direction change path 10 Ball 11 Flange part 12 Bolt hole 13 Pipe 14 Lubricant discharge port 20 Lubricant supply system DESCRIPTION OF SYMBOLS 21 Base 22 Fixed plate 23 Moving stand 24 Linear guide device 24a Rail 24b Slider 25 Support plate 26 Drive motor 27 Mounting bracket 28a, 28b Toothed pulley 29 Toothed belt 30 Controller 31 Lubricant supply device 32 Supply pipe 40 Sealing tape 42 Sealing material 44 Communication groove 46 Intermediate outlet

Claims (8)

A screw shaft having a spiral shaft raceway groove formed on an outer peripheral surface; and a nut having a nut raceway groove formed on an inner peripheral surface opposed to the shaft raceway groove, wherein the shaft raceway groove and the nut raceway groove are plural. In the ball screw device screwed through the ball,
Lubrication that forms a dummy groove parallel to the axial raceway groove, winds a pipe around the dummy groove, opens an end of the pipe into the dummy groove to serve as a lubricant discharge port, and supplies the lubricant to the pipe A ball screw device characterized in that it is an agent supply path. A screw shaft having a spiral shaft raceway groove formed on an outer peripheral surface; and a nut having a nut raceway groove formed on an inner peripheral surface opposed to the shaft raceway groove, wherein the shaft raceway groove and the nut raceway groove are plural. In the ball screw device screwed through the ball,
A dummy groove is formed in parallel with the shaft raceway groove, a space is provided by covering the dummy groove with a covering material, and an end of the space is opened in the dummy groove to serve as a lubricant discharge port, and the space is lubricated. A ball screw device characterized in that a lubricant supply path for supplying the agent is provided. In claim 1 or claim 2,
The ball screw device, wherein the lubricant discharge port is positioned at a substantially central portion of the screw shaft. In claim 1, claim 2 or claim 3,
A ball screw device, wherein at least one intermediate discharge port is formed in the middle of the lubricant supply path. In claim 4,
The ball screw device characterized in that the opening area of the intermediate discharge port is made smaller in order toward the upstream of the lubricant supply path, with the opening area of the lubricant discharge port being maximized. In claim 1 to claim 4 or claim 5,
A ball screw device characterized in that a circumferential connecting groove is provided downstream of the lubricant discharge port on the outer peripheral surface of the screw shaft, and the dummy groove and the shaft raceway groove communicate with each other. A screw shaft having a spiral shaft raceway groove formed on an outer peripheral surface; and a nut having a nut raceway groove formed on an inner peripheral surface opposed to the shaft raceway groove, wherein the shaft raceway groove and the nut raceway groove are plural. In the ball screw device screwed through the ball,
A ball screw device, wherein a dummy groove is formed in parallel with the shaft raceway groove, a pipe is wound around the dummy groove over the entire length of the screw shaft, and a cooling medium is supplied to the pipe. A screw shaft having a spiral shaft raceway groove formed on the outer peripheral surface; and a nut having a nut raceway groove formed on the inner peripheral surface opposite to the shaft raceway groove. In the ball screw device screwed through the ball,
A ball screw characterized in that a dummy groove is formed in parallel with the shaft raceway groove, a space is provided by covering the dummy groove with a covering material over the entire length of the screw shaft, and a cooling medium is supplied to the space. apparatus.