JP5830992B2 - Ball screw - Google Patents

Description

  The present invention relates to a ball screw.

  The ball screw is disposed between a nut having a spiral groove formed on the inner peripheral surface, a screw shaft having a spiral groove formed on the outer peripheral surface, and a raceway formed by the spiral groove of the nut and the spiral groove of the screw shaft. And a ball return path for returning the ball from the end point of the track to the start point, and the nut moves relative to the screw shaft as the ball rolls in the track. Ball screws are used in machine tools, injection molding machines, semiconductor device manufacturing apparatuses, and the like.

  Such a ball screw is used by supplying a lubricant to the inside of the nut. Also, if foreign matter such as dust or abrasion powder adhering to the screw shaft enters the nut, it may cause damage such as seizure of the ball or spiral groove, so it is necessary to prevent foreign matter from entering the nut. . Therefore, a ring-shaped seal is attached to the axial end of the nut for the purpose of preventing the lubricant supplied to the inside of the nut from being discharged to the outside and preventing foreign matter from entering the nut.

  The outward seal in which the tip of the lip portion faces the outside of the nut in the axial direction has an action of preventing foreign matter from entering the nut. The inward seal in which the tip of the lip portion faces the inside of the nut in the axial direction has an action of retaining the lubricant inside the nut (not discharging it to the outside). Therefore, in order to effectively obtain both actions of retaining the lubricant inside the nut and preventing foreign matter from entering the nut, it is conceivable to attach the inward seal and the outward seal in this order from the nut side.

  However, when the inward seal and the outward seal are installed in this order from the nut side, if a very small amount of foreign matter enters between the lip portion of the outward seal and the screw shaft, the foreign matter will be removed from the lip of the outward seal. It becomes easy to accumulate between a part and the lip | rip part of an inward seal. Further, if the lubricant leaks from between the lip portion of the inward seal and the screw shaft, the lubricant is likely to be scattered from the outward seal to the outside of the nut.

  Patent Document 1 discloses a ring-shaped member for retaining a lubricant (a sealing member made of a material capable of absorbing the lubricant) as a seal that can retain the lubricant inside the nut and prevent foreign matter from entering the nut. And a ring-shaped member for removing foreign matter (foreign matter removing member made of a hard material), the inner peripheral portion of both members is in contact with the spiral groove and the outer peripheral surface of the screw shaft, and the ring-shaped member for removing foreign matter is axially outside. The ones to be arranged are described.

JP 2002-364726 A

As mentioned above, the ball screw with the inward seal and the outward seal attached in this order from the nut side tends to collect very small foreign matter between the lips of both seals, and the lubricant is likely to be scattered outside the nut. There is a problem of becoming.
An object of the present invention is that a very small amount of foreign matter has entered between the lip portion of the outward seal and the screw shaft as a ball screw having both an inward seal and an outward seal attached to both end faces in the axial direction of the nut. Even in such a case, there is provided a device that prevents foreign matter from entering the nut and prevents the lubricant from scattering outside the ball screw even when the lubricant inside the nut comes out of the inward seal.

  In order to solve the above problems, a ball screw of the present invention includes a nut having a spiral groove formed on an inner peripheral surface, a screw shaft having a spiral groove formed on the outer peripheral surface, a spiral groove of the nut, and a spiral of the screw shaft. A ball disposed between the raceway grooves formed by the groove, and a ring-shaped inward seal, a spacer, and an outward seal attached to the both axial ends of the nut in order from the nut side, The inward seal, the outward seal, the spacer, and the screw shaft form a space for storing the lubricant leaking from the inward seal and the foreign matter entering from the outward seal. A discharge port for discharging to the outside is formed in the spacer or the outward seal.

  According to the ball screw of the present invention, when a very small foreign matter enters between the lip portion of the outward seal and the screw shaft, the foreign matter enters the space. When the lubricant leaks from between the lip portion of the inward seal and the screw shaft, the lubricant enters the space. And the foreign material and lubricant which entered the space can be discharged outside without being scattered from the discharge port. Therefore, it is possible to prevent foreign matter from entering the nut and prevent the lubricant from being scattered outside the ball screw.

  According to the ball screw of the present invention, even if a very small amount of foreign matter enters between the lip portion of the outward seal and the screw shaft, the foreign matter does not enter the nut, and the lubricant inside the nut is sealed inward. Even when it goes outside, the lubricant can be prevented from being scattered outside the ball screw.

It is a figure explaining the ball screw of 1st Embodiment of this invention, Comprising: It corresponds to AA sectional drawing of FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a front view explaining the ball screw of 1st Embodiment of this invention, Comprising: The screw shaft has shown the AA cross section of FIG. It is a front view which shows the state before attaching a seal | sticker to a nut with the ball screw of 1st Embodiment and 2nd Embodiment. It is a front view which shows the inward seal which comprises the ball screw of 1st Embodiment and 2nd Embodiment. They are the front view (a) which shows the spacer which comprises the ball screw of 1st Embodiment, and AA sectional drawing (b) of (a). It is a front view which shows the outward seal | sticker which comprises the ball screw of 1st Embodiment. They are the front view (a) which shows the state which fixed the inward seal to the nut in 1st Embodiment and 2nd Embodiment, and AA sectional drawing (b) of (a). It is a figure explaining the ball screw of 2nd Embodiment of this invention, Comprising: It corresponds to AA sectional drawing of FIG. It is a front view explaining the ball screw of 2nd Embodiment of this invention, Comprising: The screw shaft has shown the AA cross section of FIG. It is the front view (a) which shows the spacer which comprises the ball screw of 2nd Embodiment, and AA sectional drawing (b) of (a). It is a front view which shows the outward seal | sticker which comprises the ball screw of 2nd Embodiment.

Embodiments of the present invention will be described below.
[First Embodiment]
As shown in FIG. 1, the ball screw of this embodiment includes a nut 1, a screw shaft 2, a ball 3, an inward seal 4, a spacer 5, an outward seal 6, and an inward seal 4. The fixing screw 7 is fixed to the nut 1, and the fixing screw 8 is used to fix the spacer 5 and the outward seal 6 to the nut 1. The screw shaft 2, the inward seal 4, the spacer 5, and the outward seal 6 form a space 9 for storing the lubricant that has leaked from the inward seal 4 and the foreign matter that has entered through the outward seal 6.

A spiral groove 11 is formed on the inner peripheral surface of the nut 1, and a spiral groove 21 is formed on the outer peripheral surface of the screw shaft 2. The ball 3 is disposed between the raceway groove formed by the spiral groove 11 of the nut 1 and the spiral groove 21 of the screw shaft 2.
As shown in FIG. 3, six female screws 12 and 13 are formed at equal intervals in the circumferential direction on the outer edge portions of both end surfaces of the nut 1 in the axial direction.

  The inward seal 4 is a ring-shaped contact seal that has a lip portion 41 having an inner peripheral edge shape similar to the cross-sectional shape perpendicular to the axis of the screw shaft 2 and is in sliding contact with the screw shaft 2. The tip of the lip 41 is inclined toward the nut 1 in the axial direction. An annular base portion 42 is formed on the outer peripheral side of the lip portion 41. As shown in FIG. 4, six elongated holes 42 a and 42 b are formed at equal intervals in the circumferential direction on the outer edge portion of the base portion 42 of the inward seal 4.

  The spacer 5 has an annular shape, the outer diameter is the same as the nut 1, the inner diameter is larger than the boundary circle between the lip portions 41, 61 and the base portions 42, 62 of both seals 4, 6, and the axial dimension is an inward seal. 4 times the thickness of 4. As shown in FIG. 5, three grooves 51 extending in the radial direction are formed at equal intervals in the circumferential direction on one axial end surface of the spacer 5. On the other end surface in the axial direction of the spacer 5, three circular recesses 52 are formed at the same positions as the grooves 51 at equal intervals in the circumferential direction. In the spacer 5, three through holes 53 extending in the axial direction are formed at equal intervals in the circumferential direction at positions between the grooves 51 and the circular recesses 52.

The outward seal 6 is a ring-shaped contact seal that has a lip portion 61 having an inner peripheral edge shape similar to the cross-sectional shape perpendicular to the axis of the screw shaft 2 and is in sliding contact with the screw shaft 2. The tip of the lip 61 is inclined in the axial direction to the opposite side of the nut 1. An annular base portion 62 is formed on the outer peripheral side of the lip portion 61. As shown in FIG. 6, three long holes 62a are formed at equal intervals in the circumferential direction on the outer edge portion of the base portion 62 of the outward seal 6.
When assembling this ball screw, the screw shaft 2 in which the ball 3 is placed in the spiral groove 21 is disposed in the nut 1, and then an inward seal 4 is first attached to the axial end surface of the nut 1 with the fixing screw 7.

  Specifically, as shown in FIG. 7, the female screw 12 of the nut 1 and the long hole 42 a of the inward seal 4 are aligned, and each fixing screw 7 is inserted from the three long holes 42 a, and the phase of the inward seal 4 is reached. After adjusting (circumferential mounting position) to an optimum phase in order to obtain good lubricant holding performance, the tip of the fixing screw 7 is screwed into the female screw 12 of the nut 1. In this state, as shown in FIG. 7A, the internal thread 13 of the nut 1 can be seen in the long hole 42 b of the inward seal 4.

  Next, the spacer 5 is disposed outside the inward seal 4. At that time, the head of the fixing screw 7 is put into the circular recess 52 with the circular recess 52 side of the spacer 5 facing the inward seal 4. Next, the outward seal 6 is disposed outside the spacer 5. At that time, the female screw 13 of the nut 1, the elongated hole 42 b of the inward seal 4 and the elongated hole 62 a of the outward seal 6 are matched, and the fixing screws 8 are inserted from the three elongated holes 62 a, and the outward seal 6 After adjusting the phase (circumferential mounting position) to an optimal phase in order to obtain good foreign matter intrusion prevention performance, the tip of the fixing screw 8 is screwed into the female screw 13 of the nut 1. 1 and 2 illustrate this state.

In this state, a space 9 is formed by the inward seal 4, the inner peripheral surface of the spacer 5, the outer peripheral surface of the screw shaft 2, and the outward seal 6. Further, a hole connecting the space 9 and the outside is formed by the groove 51 of the spacer 5 and the surface of the spacer 5 on the outer seal 6 side. This hole is a discharge port for discharging the lubricant and foreign matter present in the space 9.
Therefore, in the ball screw of this embodiment, when a very small foreign matter enters between the lip portion 61 of the outward seal 6 and the screw shaft 2, the foreign matter enters the space 9. When the lubricant leaks from between the lip portion 41 of the inward seal 4 and the screw shaft 2, the lubricant enters the space 9. By driving the ball screw, the foreign matter and the lubricant that have entered the space 9 are agitated, so that the pressure in the space 9 increases. Along with this, foreign matter and lubricant that have entered the space 9 are discharged to the outside from the groove (discharge port) 51 of the spacer 5, and scattering to the outside can be prevented.

  Therefore, according to the ball screw of this embodiment, even when a very small foreign matter enters between the lip portion 61 of the outward seal 6 and the screw shaft 2, the foreign matter does not enter the nut 1, and the nut Even when the lubricant in 1 comes out of the inward seal 4, the lubricant can be prevented from being scattered outside the ball screw.

[Second Embodiment]
As shown in FIG. 8, the ball screw of this embodiment includes a nut 1, a screw shaft 2, a ball 3, an inward seal 4, a spacer 5A, an outward seal 6A, and an inward seal 4. The fixing screw 7 is fixed to the nut 1, and the fixing screw 8 is used to fix the spacer 5 </ b> A and the outward seal 6 </ b> A to the nut 1. The screw shaft 2, the inward seal 4, the spacer 5 </ b> A, and the outward seal 6 </ b> A form a space 9 for storing the lubricant that has leaked from the inward seal 4 and the foreign matter that has entered through the outward seal 6 </ b> A.
The nut 1, the screw shaft 2, the ball 3, and the inward seal 4 are the same as those in the first embodiment.

  The spacer 5A has an annular shape, the outer diameter is the same as the nut 1, the inner diameter is larger than the boundary circle between the lip portions 41, 61 and the base portions 42, 62 of both seals 4, 6A, and the axial dimension is inward. The thickness of the seal 4 is about 4 times. As shown in FIG. 10, three circular recesses 52 are formed at equal intervals in the circumferential direction on one end surface of the spacer 5 in the axial direction. In the spacer 5, three through holes 53 extending in the axial direction are formed at positions between the circular recesses 52 at equal intervals in the circumferential direction.

The outward seal 6 </ b> A is a ring-shaped contact seal that has a lip portion 61 having an inner peripheral edge similar to the cross-sectional shape perpendicular to the axis of the screw shaft 2, and is in sliding contact with the screw shaft 2. The tip of the lip 61 is inclined in the axial direction to the opposite side of the nut 1. An annular base portion 62 is formed on the outer peripheral side of the lip portion 61. As shown in FIG. 11, three long holes 62a are formed at equal intervals in the circumferential direction on the outer edge of the base 62 of the outward seal 6A. Further, four through holes 63 extending in the axial direction are formed at equal intervals in the circumferential direction around the lip portion 61 of the base portion 62.
When assembling this ball screw, the screw shaft 2 in which the ball 3 is placed in the spiral groove 21 is disposed in the nut 1, and then an inward seal 4 is first attached to the axial end surface of the nut 1 with the fixing screw 7.

  Specifically, as shown in FIG. 7, the female screw 12 of the nut 1 and the long hole 42 a of the inward seal 4 are aligned, and each fixing screw 7 is inserted from the three long holes 42 a, and the phase of the inward seal 4 is reached. After adjusting (circumferential mounting position) to an optimum phase in order to obtain good lubricant holding performance, the tip of the fixing screw 7 is screwed into the female screw 12 of the nut 1. In this state, as shown in FIG. 7A, the internal thread 13 of the nut 1 can be seen in the long hole 42 b of the inward seal 4.

  Next, the spacer 5 </ b> A is disposed outside the inward seal 4. At that time, the head of the fixing screw 7 is inserted into the circular recess 52 with the circular recess 52 side of the spacer 5 </ b> A facing the inward seal 4. Next, the outward seal 6 </ b> A is disposed outside the spacer 5. At that time, the female screw 13 of the nut 1, the elongated hole 42b of the inward seal 4 and the elongated hole 62a of the outward seal 6A are combined, and the fixing screws 8 are inserted through the three elongated holes 62a, and the outward seal 6A. After adjusting the phase (circumferential mounting position) to an optimal phase in order to obtain good foreign matter intrusion prevention performance, the tip of the fixing screw 8 is screwed into the female screw 13 of the nut 1. Figures 8 and 9 illustrate this situation.

In this state, a space 9 is formed by the inward seal 4, the inner peripheral surface of the spacer 5, the outer peripheral surface of the screw shaft 2, and the outward seal 6A. Further, the through hole 63 of the outward seal 6 </ b> A serves as a discharge port for discharging the lubricant and foreign matters existing in the space 9.
Therefore, in the ball screw of this embodiment, when a very small foreign object enters between the lip portion 61 of the outward seal 6A and the screw shaft 2, the foreign object enters the space 9. When the lubricant leaks from between the lip portion 41 of the inward seal 4 and the screw shaft 2, the lubricant enters the space 9. By driving the ball screw, the foreign matter and the lubricant that have entered the space 9 are agitated, so that the pressure in the space 9 increases. Along with this, foreign matter and lubricant that have entered the space 9 are discharged to the outside from the through hole 63 of the outward seal 6A, and scattering to the outside can be prevented.

  Therefore, according to the ball screw of this embodiment, even if a very small foreign matter enters between the lip portion 61 of the outward seal 6A and the screw shaft 2, the foreign matter does not enter the nut 1, and the nut Even when the lubricant in 1 comes out of the inward seal 4, the lubricant can be prevented from being scattered outside the ball screw.

DESCRIPTION OF SYMBOLS 1 Nut 11 Spiral groove of nut 12,13 Female thread of nut end surface 2 Screw shaft 21 Spiral groove of screw shaft 3 Ball 4 Inward seal 41 Lip part 42 Base part 42a, 42b Long hole 5 Spacer 5A Spacer 51 Groove 52 Circular recess 53 Spacer through-hole 6 Outward seal 6A Outward seal 61 Lip part 62 Base 62a Elongated hole 7 Fixing screw 8 Fixing screw 9 Space formed by inward seal, outward seal, spacer and screw shaft

Claims (1)

A nut having a spiral groove formed on the inner peripheral surface;
A screw shaft having a spiral groove formed on the outer peripheral surface;
A ball disposed between a raceway groove formed by a spiral groove of a nut and a spiral groove of a screw shaft;
A ring-shaped inward seal, spacer, and outward seal that are attached to both ends of the nut in the axial direction from the nut side,
Have
The inward seal, the outward seal, the spacer, and the screw shaft form a space for storing the lubricant that has leaked from the inward seal and the foreign matter that has entered from the outward seal.
A discharge port for discharging the lubricant and foreign matters existing in the space to the outside is formed by a radially extending groove provided on one axial end surface of the spacer and the spacer side surface of the outward seal. A ball screw characterized by being made.

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