JP2009085337A - Seal device for rotary shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal device for a rotary shaft capable of preventing invasion of foreign matter such as coolant from a clearance between the rotary shaft and a housing. <P>SOLUTION: This seal device includes a substantially cylindrical housing having a storage space, a main shaft spindle 2 rotatably stored in the storage space and disposed with keeping cylindrical clearance from an inner circumference surface of the housing 1. An absorbent 5 formed in a ring shape out of porous material is disposed on at least one of the housing 1 and the main shaft spindle 2 with facing to the clearance 30. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rotary shaft sealing device that seals a clearance between a rotary shaft such as a spindle device of a machine tool and a housing.

  A tool holder is fixed to the tip of the spindle of the machining center, and processing such as workpiece cutting is performed by rotating the spindle. The spindle is rotatably accommodated in the housing. A clearance is formed between the spindle and the housing. A seal mechanism is provided to prevent damage to the bearing and the like due to coolant entering the clearance. Examples of the seal mechanism include a contact seal, a screw labyrinth, a mechanical labyrinth, and an air seal.

  The contact seal seals the V ring against the spindle by a spring or the like. However, the contact seal causes a contact friction of the spindle with respect to the V ring, so that the peripheral speed of the spindle is limited, and is not suitable for sealing a spindle that rotates at a high speed.

  The screw labyrinth exerts a sealing effect by rotating the spindle so that the coolant adhering to the threaded portion rotates with the spindle and extruding the coolant in the thrust direction of the screw by the effect of the screw. However, the effect of pushing out all the coolant adhering to the spindle cannot be expected.

The mechanical labyrinth suppresses the intrusion of the coolant by complicating the structure of the clearance. However, it cannot be expected to completely prevent the coolant from entering.
The air seal blows air to the clearance from an annular passage disposed in the housing (Patent Document 1). However, as with the air labyrinth, the air seal cannot be expected to extrude all of the coolant with air.

Patent Document 2 proposes sealing the coolant in the clearance with a water-absorbing polymer. This water-absorbing polymer is a heat-sensitive gel whose state changes depending on temperature, and absorbs and swells in a low temperature region to close the clearance, and discharges and shrinks in a high temperature region to release the clearance and reduce rotational friction. However, in an environment where there is no temperature change, the state of the water-absorbing polymer does not change. For this reason, although the clearance is blocked at a low temperature, there is a problem that the clearance is opened at a high temperature to allow entry of coolant or the like.
JP 2000-18395 A Japanese Utility Model Publication No. 6-35661

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rotary shaft sealing device capable of preventing entry of foreign matters such as coolant from the clearance between the rotary shaft and the housing.

  The rotary shaft sealing device of the present invention is disposed between a cylindrical housing having a housing space and a cylindrical clearance between the housing space and the inner peripheral surface of the housing. A rotating shaft sealing device having a rotating shaft, wherein at least one of the housing and the rotating shaft is provided with an absorbent body made of a porous material formed in a ring shape so as to face the clearance. (Claim 1).

  According to the said structure, the absorber which consists of a porous material formed in the ring shape is arrange | positioned at least one of a housing and the said rotating shaft facing a clearance. For this reason, it is possible to prevent the foreign matter such as the coolant that has entered the clearance from being absorbed by the absorber and entering the inner side in the axial direction from the position where the absorber is disposed. Therefore, an excellent sealing effect can be exhibited. Moreover, since the absorber can maintain its shape even if the environment such as temperature and load changes, the clearance facing the absorber can be secured. Therefore, it is also suitable for sealing a rotating shaft that rotates at a high speed.

  The absorber is preferably made of a hydrophilic porous material (claim 2). Since foreign substances such as coolant are often hydrophilic, the foreign substances can be more effectively absorbed by the absorber.

  It is preferable that a drain communication hole for discharging foreign matter absorbed by the absorber is provided in at least one of the housing in which the absorber is disposed and the rotating shaft (Claim 3). Thereby, the foreign material absorbed by the absorber is removed from the drain communication hole. Therefore, clogging of the absorber can be suppressed, and the absorber can be used for a long time. Moreover, since the drain communication hole is provided in at least one of the housing in which the absorber is disposed and the rotating shaft, the foreign matter absorbed by the absorber can be discharged into the drain communication hole with a simple structure. .

  It is preferable that the axial direction of the rotating shaft is a horizontal direction, and the drain communication hole is disposed at a lower end of the absorber. When the axial direction of the rotating shaft is horizontal, the axial direction of the ring-shaped absorber is also horizontal. The foreign matter absorbed by the absorber tends to move to the lower end of the absorber due to its own weight. For this reason, by disposing the drain communication hole at the lower end of the absorber, almost all of the foreign matter absorbed by the absorber can be collected by the drain communication hole. In addition, an axial direction means the axial direction of at least one of the housing in which the absorber is arrange | positioned, and a rotating shaft.

  It is preferable that the drain communication hole is connected to a suction device that sucks the foreign matter. Thereby, foreign substances such as coolant absorbed by the absorber are forcibly removed by the suction force of the suction device. Therefore, clogging of the absorber can be effectively suppressed.

  The absorber is preferably disposed in the housing (claim 6). In this case, since the housing is disposed on the outer peripheral side of the rotating shaft, the absorber disposed in the housing is disposed on the outer peripheral side of the rotating shaft. Due to the centrifugal air pressure caused by the rotation of the rotating shaft, foreign matter such as coolant is pressed against the absorber disposed on the outer peripheral side of the rotating shaft. For this reason, the absorber can absorb a foreign material more effectively than the case where it arrange | positions to a housing compared with the case where it arrange | positions to a rotating shaft.

  It is preferable that the absorber is detachably fixed to the housing. Thereby, an absorber can be removed and wash | cleaned, or it can replace | exchange for a new article.

  As described above, the rotary shaft sealing device of the present invention has a clearance formed by disposing an absorbent body made of a porous material formed in a ring shape on at least one of the housing and the rotary shaft so as to face the clearance. Since the foreign matter such as the coolant that has intruded into the body is absorbed, it is possible to prevent the foreign matter from entering inward in the axial direction from the position where the absorber is disposed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an axial sectional view of a rotary shaft sealing device of the present embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the axial end surface of the rotating shaft. As shown in FIGS. 1 and 2, the rotary shaft sealing device is a main shaft sealing device of a horizontal machining center, and is accommodated in a substantially cylindrical housing 1 having a storage space 3 and rotatably in the storage space 3. It has a main spindle 2 as a rotation axis. The main spindle 2 is disposed between the inner peripheral surface of the housing 1 and a cylindrical clearance 30 that opens to the axial end surface 30a. In the housing 30, the absorbent body 5 made of a hydrophilic porous material formed in a ring shape is disposed facing the clearance 30. Hereinafter, the rotary shaft sealing device of the present embodiment will be described in more detail.

  As shown in FIG. 1, the housing 1 has a substantially cylindrical shape having an accommodating space 3 having a circular cross section inside, a main shaft housing 11, a bearing housing 12 that is fitted inside the main shaft housing 11, and a front cap. 14 and a seal cap 15 as a pressing member. The main shaft housing 11 is a substantially cylindrical member for fixing the bearing housing 12 and the motor. The bearing housing 12 is a substantially cylindrical member that rotatably supports the main spindle 2 via the bearing 13. A plurality of bearings 13 are held at predetermined intervals on the inner diameter side of the bearing housing 12. A main spindle 2 as a rotating shaft is disposed inside the bearing 13 and is rotatably supported by the bearing 13.

  The main spindle 2 is a cylindrical member for transmitting the rotation of the motor to a tool such as a cutting tool via the tool holder 23. The axial direction of the main spindle 2 is a horizontal direction. The main spindle 2 is rotationally driven by a built-in motor (not shown) fitted to the outer periphery of the main spindle 2 on the inner side in the axial direction of the bearing 13. A known clamping mechanism 21 composed of a draw bar, a disc spring, etc. (not shown) is held inside the spindle spindle 2, and a tool holder 23 that is mounted in a tapered hole at the outer end in the axial direction of the spindle spindle 2. Is to be clamped. The clamp mechanism 21 is accommodated in the push rod 22. Furthermore, the rotor of the motor is fixed to the rear end portion of the main spindle 2 via a rotor sleeve (not shown). A tool such as an unillustrated cutting tool is held at the tip of the tool holder 23, and a workpiece is processed by this tool.

  As shown in FIG. 2, a front cap 14 is attached to the axially outer ends of the spindle housing 11 and the bearing housing 12. A fitting portion 14 a formed of an annular groove is formed on the inner peripheral surface of the front cap 14 on the outer side in the axial direction than the bearing 13. A fixing portion 14b formed of an annular groove is formed adjacent to the fitting portion 14a on the inner side in the axial direction than the fitting portion 14a. A ring-shaped seal cap 15 is detachably fixed between the fitting portion 14a and the outer peripheral surface 20 of the main spindle 2. The fixing portion 14b accommodates the absorber 5 without a gap. The seal cap 15 faces the end surface 5a on the outer side in the axial direction of the absorber 5, and is fixed to the front cap 14 by fastening means such as a bolt in a state where the seal cap 15 is pressed against the absorber 5 in the inner side in the axial direction. ing.

  The seal cap 15 is formed with an annular groove 6 that is concentric with the clearance 30 and opens into the clearance 30. The annular groove 6 communicates with an air supply source (not shown) formed in the spindle housing 11 via an air passage 61 formed in the seal cap 15 and the front cap 14. The air pumped from the air supply source is supplied to the annular groove 6 through the air passage 61. The air supplied to the annular groove 6 passes through a minute clearance 30 between the main spindle 2 and the housing 1 and flows out from the axial end face 30a of the clearance 30 to the outside of the sealing device.

  An absorber 5 having a ring shape concentric with the clearance 30 is disposed on the inner side in the axial direction from the position where the annular groove 6 is formed in the clearance 30. The absorber 5 is disposed in the housing 1. The absorber 5 is arranged in a non-contact manner with a clearance 30 with respect to the main spindle 2. The deflection width of the main spindle 2 is 10 μm, and the radial width H1 of the portion of the clearance 30 where the absorber 5 is disposed is 50 to 100 μm. The width H <b> 1 is a width that can suppress the intrusion of coolant or the like and can hold the spindle spindle 2 in a non-contact state even when the spindle spindle 2 is shaken.

  The absorber 5 is a porous body made of a hydrophilic polyolefin-based material. A known technique can be used for manufacturing an absorbent body made of a hydrophilic polyolefin-based material. For example, a polyolefin material is subjected to a hydrophilic treatment, a foaming agent capable of generating a gas by heating is added and kneaded, and foamed by heating in a mold. Alternatively, the polyolefin-based material subjected to the hydrophilization treatment may be molded into a fiber shape or a particle shape, and then filled into a mold and compression-heat molded to weld the surfaces of the fibers or particles to be integrated.

  A known technique can be used as a technique for imparting hydrophilicity to the polyolefin-based material. For example, (1) blend of hydrophilic polymer resin, (2) application of hydrophilic agent such as ionic or nonionic surfactant, (3) surface modification by corona discharge treatment, plasma discharge treatment, etc. There is. Examples of the polyolefin-based material include known polyolefin-based materials such as polyethylene-based resins, polypropylene-based resins, and copolymers of ethylene, propylene and other α-olefins.

  The absorber 5 is made of a hydrophilic porous material. As the hydrophilic porous material, in addition to the hydrophilic polyolefin-based porous material, ceramic porous material, porous metal, porous carbon, porous glass, foaming agent, concrete, stone, and other inorganic porous materials are used. You can also In addition, since the clearance is managed with minute accuracy, it is desirable that the material be easy to machine.

  The absorber 5 is preferably an open cell in which the holes 50 communicate with each other. Thereby, the adsorbed foreign matter 8 such as coolant can pass through the hole 50 in the absorber 5 and can be discharged into the drain communication hole 7 opened at the lower end 5 c of the absorber 5.

  As shown in FIG. 1, the axial direction of the absorbent body 5 is the same as the axial direction of the rotary shaft 2, and a drain communication hole 7 for collecting foreign matter absorbed by the absorbent body 5 is disposed at the lower end 5 c of the absorbent body 5. Is arranged. A groove 14 c that extends in an arc shape in the circumferential direction of the front cap 14 is formed in the lower portion of the inner peripheral surface of the front cap 14. The groove 14 c forms a drain communication hole 7 between the lower end 5 c of the outer peripheral surface of the absorber 5. A seal cap 14 is disposed outside the drain communication hole 7 in the axial direction. The drain communication hole 7 communicates with a suction device such as a vacuum pump through a discharge passage 71 formed in the front cap 14 and the spindle housing 11.

  The operation of the rotary shaft sealing device of this embodiment will be described. As shown in FIG. 2, high-pressure air is supplied from the air supply source to the annular groove 6 through the air passage 61. Then, air is led out from the annular groove 6 to the clearance 30. This air pressure prevents entry of foreign matter 8 such as coolant from the outside of the clearance 30 in the axial direction.

  An absorber 5 is disposed in the housing 1 on the inner side in the axial direction of the annular groove 6 for air seal. For this reason, when the foreign matter 8 such as coolant passes through the air seal of the annular groove 6 and enters the axially inner side of the clearance 30, it is attracted to the absorber 5 made of a hydrophilic porous material and absorbed by the absorber 5. The Since the absorber 5 is a porous body having open cells, the absorbed foreign matter 8 moves downward through the holes 50 in the absorber 5 by its own weight. A drain communication hole 7 connected to the suction device is disposed at the lower end 5c of the absorber 5. For this reason, the foreign matter 8 absorbed by the absorber 5 passes through the hole 50 in the absorber 5 and is sucked into the drain communication hole 7 at the lower end 5c, and is forced to the outside of the sealing device through the drain discharge passage 71. Discharged.

  In the present embodiment, an absorber 5 made of a porous material formed in a ring shape so as to surround the clearance 30 in the circumferential direction is disposed in the housing 1. For this reason, it is possible to prevent the foreign matter 8 such as the coolant that has entered the clearance 30 from being absorbed by the absorber 5 and entering the inner side in the axial direction from the position where the absorber 5 is disposed. Therefore, an excellent sealing effect can be exhibited. The foreign matter 8 such as coolant is often a liquid. For this reason, the absorbent body 5 made of a hydrophilic porous material has a high affinity with the foreign matter 8, absorbs the foreign matter 8, and suppresses intrusion in the axial direction from the absorbent body 5.

  A drain communication hole 7 is formed at the lower end 5 c of the absorber 5. For this reason, the foreign material 8 absorbed by the absorber 5 is removed from the drain communication hole 7 to the outside of the sealing device. Therefore, clogging of the absorber 5 can be suppressed, and the absorber 5 can be used for a long time.

  Further, since the seal cap 15 is detachably fixed from the front cap 14 of the housing 1, when the absorber 5 is clogged with foreign matter 8 such as coolant, the absorber 5 is removed and cleaned or new. Can be exchanged for. Further, a seal cap 15 is disposed outside the drain communication hole 7 in the axial direction. For this reason, when the seal cap 15 is removed, the drain communication hole 7 is exposed to the outside. For this reason, the foreign matter accumulated in the drain communication hole 7 can be removed, and cleaning is easy. Therefore, it is excellent in maintainability.

  In the present embodiment, the absorber 5 is disposed in the housing 1 located on the outer peripheral side of the main spindle 2. For this reason, the foreign substance 8 such as coolant is pressed against the absorber 5 by the air pressure in the centrifugal direction caused by the rotation of the spindle 2. For this reason, the absorber 5 can absorb the foreign material 8 more effectively when disposed in the housing 1 than when disposed in the main spindle 2. However, the absorber 5 may be disposed on the outer peripheral surface of the main spindle 2. Further, the absorbent body 5 may be disposed not only on the housing 1 but also on the main spindle 2.

  The rotary shaft sealing device of the present embodiment is a horizontal machining center in which the main spindle 2 rotates about a horizontal axis as shown in FIG. 1. However, as shown in FIG. A vertical machining center that rotates about a vertical axis may also be used. In this case, the foreign matter absorbed by the absorber 5 moves to the axial end surface 5d below the absorber 5 by its own weight. In this case, a drain communication hole 7 having an opening having substantially the same radial cross section as that of the absorber 5 is disposed on the lower axial end surface 5 d of the absorber 5. Thereby, almost all of the foreign matter absorbed by the absorber 5 can be collected by the drain communication hole 7.

  Moreover, in the said embodiment, although the air seal mechanism which blows off air to the clearance 30 from the annular groove 6 and the absorber 5 are provided side by side, it can also be used as a sealing device by an absorber alone. Further, instead of the air seal mechanism, another seal mechanism such as a screw labyrinth mechanism or a mechanical labyrinth mechanism and an absorber can be provided side by side. Even in such a case, the absorber may be disposed on the inner side in the axial direction than the other sealing mechanisms. This is because clogging of the absorber is suppressed and long-term use is possible.

  Moreover, in the said embodiment, although the absorber 5 is pressed and fixed to the axial direction with the structural member of the sealing device called the seal cap 15, it fixes with the member for absorber fixing separate from a sealing device. Also good.

  Moreover, in the said embodiment, although the example which applied the sealing apparatus of the rotating shaft of this invention to the sealing apparatus of the spindle of a machining center is given, it is not limited to this, The grindstone axis | shaft and workpiece | work of a grinder The present invention may be applied to a work shaft sealing device to which is fixed. If it is the same structure, it can apply not only to a machine tool but to other uses.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention described in the claims. Of course there is.

It is an axial sectional view of a seal device of a rotating shaft of an embodiment of the present invention. It is principal part sectional drawing of the axial direction end surface vicinity of the rotating shaft of embodiment of this invention. It is explanatory drawing which shows the positional relationship of an absorber and a drain communicating hole when the axial direction of a main spindle is a vertical direction.

Explanation of symbols

1: housing, 2: spindle, 3: accommodating space, 5: absorber, 5a: axially outer end surface of the absorber, 5c: lower end of the absorber, 5d; axial end surface on the lower side of the absorber, 6: Annular groove, 7: drain communication hole, 8: foreign matter, 11: spindle housing, 12: bearing housing, 13: bearing, 14: front cap, 15: seal cap, 30: clearance, 30a: axial end face, 61: air Passage, 71 discharge passage.

Claims (7)

A rotating shaft having a cylindrical housing having a receiving space, and a rotating shaft that is rotatably accommodated in the receiving space and disposed with a cylindrical clearance between the inner peripheral surface of the housing and the rotating shaft. In the sealing device,
At least one of the housing and the rotating shaft is provided with an absorbent body made of a porous material formed in a ring shape so as to face the clearance.   2. The rotary shaft sealing device according to claim 1, wherein the absorber is made of a hydrophilic porous material.   2. A drain communication hole for discharging foreign matter absorbed by the absorber is provided in at least one of the housing in which the absorber is disposed and the rotating shaft. Item 3. The rotary shaft sealing device according to Item 2.   The axial direction of the said rotating shaft is a horizontal direction, The said drain communicating hole is arrange | positioned at the lower end of the said absorber, The sealing device of the rotating shaft of Claim 3 characterized by the above-mentioned.   5. The rotary shaft sealing device according to claim 3, wherein the drain communication hole is connected to a suction device that sucks the foreign matter.   The rotary shaft sealing device according to claim 1, wherein the absorber is disposed in the housing.   The rotary shaft sealing device according to claim 6, wherein the absorber is detachably fixed to the housing.