JP2016084912A - Spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of a lubricant to the outside of a housing without generating heat, in a spindle of which an arrangement portion of a sliding bearing member is immersed in a lubricant.SOLUTION: A spindle device is provided with a partitioning wall 18A having an opening 46 externally surrounding an extension portion of a spindle 24 extended from a slide bearing member 36 to define an annular space 48 with an outer periphery of the spindle 24, an air passage 70 communicated with the annular space 48 defined at a side separating from the slide bearing member 36, of the partitioning wall 18A to supply pressurized air, and an exhaust passage 74 releasing a part between the slide bearing member 36 and a side of the partitioning wall 18A opposed to the slide bearing member 36, to the external of a housing assembly 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a main shaft device, and more particularly to a main shaft device in which a main shaft is supported by a sliding bearing.

  2. Description of the Related Art As a main spindle device used in a machine tool, one that supports a main spindle by a sliding bearing called a metal bearing is known (for example, Patent Document 1). As a plain bearing device, a non-circular shaped plain bearing member called a McKensen bearing is used, and a plurality of circumferential positions between the inner circumference of the plain bearing member and the outer circumference of the main shaft, often at intervals of 120 degrees. Wedge-shaped gaps (pressure generators) are formed at three locations, and the rotating shaft (main shaft) is supported by dynamic pressure (oil film pressure) generated by drawing lubricating oil (non-pressure viscous fluid) into the gaps. What is performed is known (for example, Patent Document 2).

JP 2004-9180 A JP 2001-65548 A

  In the dynamic pressure type sliding bearing device, in order to obtain high concentric support accuracy, the entire arrangement of the sliding bearing member is arranged so that the pressure generating parts at a plurality of locations around the circumference of the main shaft generate equal dynamic pressure. It is preferable to be immersed in the lubricating oil, and all of the plurality of pressure generating portions are filled with the lubricating oil under the same conditions.

  The main shaft extends in the axial direction from the slide bearing member, and protrudes to the outside of the housing through a through hole formed in the housing containing the main shaft and the slide bearing member. It is necessary to prevent the lubricating oil from leaking out of the housing through the gap between the outer periphery of the main shaft and the inner periphery of the through hole. Although it is conceivable to prevent this leakage by using a general contact-type oil seal, heat is generated by rotational friction between the main shaft and the oil seal, leading to a decrease in positional accuracy due to thermal expansion of the main shaft.

  The problem to be solved by the present invention is to prevent the lubricating oil from leaking out of the housing without generating heat in the main shaft in which the arrangement portion of the sliding bearing member is immersed in the lubricating oil.

  The spindle apparatus according to the present invention accommodates a spindle (24), a slide bearing member (36) that supports a journal portion (24B) of the spindle (24), a spindle (24), and a slide bearing member (36). A spindle device (10) having a housing (12), wherein the sliding bearing member (36) is immersed in lubricating oil, and extending the spindle (24) extending from the sliding bearing member (36). A partition wall (18A) having an opening (46) that surrounds the protruding portion (24E) and defines an annular gap (48) between the outer periphery of the main shaft (24), and the partition wall (18A), An air passage (70) defined on a side away from the sliding bearing member (36) and communicating with the annular gap (48) and supplied with pressurized air, the sliding bearing member (36) and the partition wall (18A) ) To the outside of the housing (12). And a gas-passage (74).

  According to this configuration, the air flowing out from the air passage (70) into the annular gap (48) and flowing between the sliding bearing member (36) and the side of the partition wall (18A) facing the sliding bearing member (36). Since the compressed air is discharged out of the housing (12) through the exhaust passage (74), the back pressure does not increase, and the space between the sliding bearing member (36) and the partition wall (18A) through the annular gap (48). As a result, the flow of the pressurized air flowing to the side is ensured, and it is reliably avoided that the lubricating oil leaks from the sliding bearing member (36) side through the annular gap (48) to the outside. And since this is performed in a non-contact manner that does not cause rotational friction, there is no heat wear.

  In the spindle device according to the present invention, preferably, the partition wall (18A) is a part of the housing (12), and the air passage (70) is a radial passage (66) provided in the housing (12). And an annular passage (68) communicating with the radial passage (66) and surrounding the main shaft (24).

  According to this configuration, it is more reliably avoided that the pressurized air uniformly flows out over the entire area of the annular gap (48) and the lubricating oil leaks outside through the annular gap (48).

  In the spindle device according to the present invention, a labyrinth seal (72) is preferably formed on the side further away from the sliding bearing member (36) than the air passage (70).

  According to this configuration, even if the lubricating oil leaks to the front side from the annular gap (48), the leakage is prevented in a fail-safe manner.

  The spindle device according to the present invention is preferably configured such that a radial direction from the outer peripheral side of the spindle (24) between the sliding bearing member (36) and the side of the partition wall (18A) facing the sliding bearing member (36). An outwardly expanded expansion chamber (62) is defined.

  According to this configuration, since the expansion chamber (62) becomes a space expanded from the annular gap (48), the flow of pressurized air from the annular gap (48) to the expansion chamber (62) is favorably performed. The effect of preventing the lubricating oil in the expansion chamber (62) from leaking outside through the annular gap (48) is improved.

  The main shaft device according to the present invention is preferably arranged between the inner periphery of the housing (12) and the outer periphery of the main shaft (24) on the end side away from the partition wall (18A) of the sliding bearing member (36). An oil retaining ring (50) for narrowing the gap is attached to any one of the inner periphery of the housing (12) and the outer periphery of the main shaft (24) in a non-contact state with respect to the other. (50) has a lubricating oil supply passage (52) for supplying lubricating oil on the sliding bearing member (36) side.

  According to this configuration, since the oil retaining ring (50) is provided, the amount of lubricating oil filled in the housing (12) can be reduced.

  According to the spindle device of the present invention, the pressurized air that flows out from the air passage into the annular gap and flows between the sliding bearing member and the partition wall facing the sliding bearing member is discharged out of the housing through the exhaust passage. Therefore, the back pressure does not increase, the flow of pressurized air flowing from the annular gap between the sliding bearing member and the partition wall is ensured, and the lubricating oil passes through the annular gap from the sliding bearing member side to the outside. Leakage into the water is reliably prevented without generating heat.

The longitudinal cross-sectional view which shows one Embodiment of the main shaft apparatus by this invention. The expanded longitudinal cross-sectional view of the principal part of the spindle apparatus by this embodiment. FIG. 3 is a sectional view taken along line III-III in FIG. 2.

  Hereinafter, one embodiment of a spindle device according to the present invention will be described with reference to FIGS.

  The spindle device 10 has a cylindrical housing assembly 12. The housing assembly 12 includes a coupling body of the front housing member 14 and the rear housing member 16, a front end member 18 fixed to the front end of the front housing member 14, and a rear end fixed to the rear end of the rear housing member 16. And an end member 20. These are integrated by bolts (not shown) and have an internal space 22 of a circular cross section penetrating in the axial direction.

  A main shaft 24 is disposed in the internal space 22. The main shaft 24 extends on the central axis of the internal space 22, and the front portion is rotatably supported by a sliding bearing device 26, and the rear portion is rotatably supported by a rolling bearing device 30 using four rows of ball bearings 28. Has been. The front end of the main shaft 24 extends forward from the front end member 18, and this extended portion is a tapered shank portion 24A to which a tool holder or the like is attached.

  The plain bearing device 26 has a bearing case 32 that is inserted into the front side of the internal space 22 and fixed to the front housing member 14. The bearing case 32 has a tapered hole 34 whose diameter decreases toward the rear. A sliding bearing member 36 is inserted into the tapered hole 34.

  The sliding bearing member 36 is made of a metal such as white metal and has a non-circular shape called a McKensen bearing, as shown in FIG. 3, and includes a central hole 38 through which the main shaft 24 passes, and a circumferential direction. A tapered thick portion 36A formed at three locations (equal intervals of 180 degrees) and fitted into the tapered hole 34, and a thin portion 36B connecting adjacent thick portions 36A. The main shaft 24 forms a journal portion 24 </ b> B that is a straight shaft portion that is rotatably supported by a sliding bearing member 36 at a portion that passes through the center hole 38. An annular gap 40 for forming an oil film is formed between the outer peripheral surface of the journal portion 24 </ b> B and the inner peripheral surface of the center hole 38.

  The sliding bearing member 36 is pushed toward the small diameter side of the tapered hole 34 by the pressure ring 42 screwed to the bearing case 32, so that the taper engagement (wedge engagement) between the thick portion 36A and the tapered hole 34 is achieved. At the same time, the thin portion 36B is elastically deformed radially outward. Due to this elastic deformation, the annular gap 40 is deformed into a wedge shape extending in the circumferential direction in each thick portion 36A, and the wedge-shaped portion forms a pressure generating portion by an oil film.

  The main shaft 24 extends forward from the sliding bearing member 36, and as shown in FIG. 2, the extending portion is sequentially formed from the journal portion 24B side with a screw shaft portion 24C and an annular ridge portion 24D. The straight shaft portion is an extended portion 24E, and the aforementioned taper shank portion 24A. A nut 44 is threadedly engaged with the screw shaft portion 24C.

  The front end member 18 forms an end wall on the front side of the housing assembly 12, and the extension portion 24 </ b> E passes through the opening 46 having a circular cross-sectional shape formed through the center portion, thereby removing the extension portion 24 </ b> E. An enclosing partition wall is formed, and an annular gap 48 is defined between the outer peripheral surface of the extending portion 24E and the inner peripheral surface of the opening 46. Since the annular gap 48 is a minute gap, the front end member 18 forms a non-contact metal seal (oil retaining portion).

  In the present embodiment, the partition wall referred to in the claims and the means for solving the problem is, as indicated by reference numeral 18A in FIG. The portion on the side of the sliding bearing member 36 is indicated.

  An oil retaining ring 50 (see FIG. 1) is fixed to the rear end portion of the front housing member 14 located on the rear side (the end side away from the front end member 18 (partition wall)) from the sliding bearing member 36. The oil retaining ring 50 is in non-contact with the outer peripheral surface of the main shaft 24 with respect to the other, narrows the gap between the inner periphery of the front housing member 14 and the outer periphery of the main shaft 24, and acts as an oil dam.

  An oil supply passage 52 is formed in the front housing member 14. The oil supply passage 52 communicates with the internal space 22 on the sliding bearing member 36 side from the oil retaining ring 50. Lubricating oil (viscous incompressible fluid) pressurized from the outside is supplied to the oil supply passage 52, and the lubricating oil is formed between the front end member 18 that forms a metal seal in the inner space 22 and the oil retaining ring 50. The housing assembly 12 is filled so as to fill the entire space including the annular gap 40 therebetween. The presence of the oil retaining ring 50 can reduce the amount of lubricating oil filled in the housing assembly 12.

  In the case of the horizontal spindle device 10, the lubricating oil does not necessarily fill the entire space of the internal space 22 between the front end member 18 that forms a metal seal and the oil retaining ring 50. The inside of the annular gap 40 need not be filled in, but may be filled with lubricating oil at a liquid level in which the entire annular gap 40 is immersed in the lubricating oil.

  Lubricating oil is supplied from the oil supply passage 52 to the annular gap 40 in the concave portion 54 formed in the inner peripheral portion of the front housing member 14, the annular groove 56 formed in the outer peripheral portion of the bearing case 32, and in the bearing case 32. The oil passage 58 formed in the passage, the passage passing through the expansion chamber 60 on the rear side of the bearing case 32, and the passage extending through the oil passage 58 and passing through the front expansion chamber 62 of the bearing case 32 and the outer peripheral surface of the journal portion 24B. It is done with a route. Lubricating oil is supplied from the oil supply passage 52 to the expansion chamber 62 by an annular gap 64 formed between the inner peripheral surface of the front housing member 14 and the outer peripheral surface of the bearing case 32. The expansion chamber 62 is an expansion chamber in which the space between the sliding bearing member 36 and the front end member 18 (the partition wall facing the sliding bearing member 36) is expanded radially outward.

  The front end member 18 includes a radial passage 66 and an air passage 70 that communicates with the radial passage 66 and includes an annular passage 68 that surrounds the extending portion 24E. The air passage 70 is defined on the side (front side) of the partition wall 18 </ b> A away from the sliding bearing member 36 and communicates with the annular gap 48, and is supplied with pressurized air from the outside.

  An air seal 72 due to the flow of a part of the pressurized air supplied to the annular passage 68 flows into the gap between the front end member 18 and the extending portion 24E on the side (front side) away from the sliding bearing member 36 from the air passage 70. Is configured.

  The front end member 18 has an exhaust passage 74 that opens between the sliding bearing member 36 and the partition wall 18 </ b> A facing the sliding bearing member 36, that is, the upper portion of the expansion chamber 62 to the outside of the housing assembly 12. Is formed.

  As shown in FIG. 1, the rear housing member 16 and the rear end member 20 have an oil discharge passage 75 for discharging the lubricating oil leaked to the rear side through the gap of the oil retaining ring 50 to the outside of the housing assembly 12. , 76 are formed. The rear end member 20 is formed with an oil discharge passage 78 for discharging the lubricating oil that has passed through the rolling bearing device 30 and leaked to the rear side to the outside of the housing assembly 12.

  The rear end portion 24 </ b> F of the main shaft 24 extends rearward from the rear end member 20 through an opening 80 having a circular cross section formed in the rear end member 20. The rear end member 20 is formed with an air passage 84 for supplying a pressurized air to the annular gap 82 between the inner peripheral surface of the opening 80 and the outer peripheral surface of the rear end portion 24F to perform a non-contact type air seal. Yes.

  The amount of lubricating oil supplied from the oil supply passage 52 to the inside of the housing assembly 12, in other words, to the slide bearing device 26 is naturally outside the housing assembly 12 from the exhaust passage 74 and the exhaust oil passages 75, 76, 78. The annular gap 40 between the journal portion 24B and the slide bearing member 36 is always filled with lubricating oil, and an oil film is formed in the annular gap 40.

  When the main shaft 24 rotates, the lubricating oil is drawn into the portion where the annular gap 40 is deformed into a wedge shape in the portion corresponding to each thick portion 36A of the sliding bearing member 36 as the main shaft 24 rotates. Dynamic pressure is generated in the deformed portion of the shape. With this dynamic pressure, the main shaft 24 is rotatably supported by the sliding bearing member 36 in a non-contact state.

  The pressurized air supplied to the air passage 70 flows out (jets) from the annular passage 68 to the annular space 48, flows through the annular space 48 toward the expansion chamber 62, and flows out from the annular space 48 into the expansion chamber 62. . The pressurized air that has flowed into the expansion chamber 62 flows as bubbles in the lubricating oil filling the expansion chamber 62 and is discharged out of the housing assembly 12 together with the lubricating oil from the exhaust passage 74.

  By discharging the pressurized air from the exhaust passage 74, the internal pressure of the expansion chamber 62 is not increased by the pressurized air, that is, the back pressure is not increased, and the additional pressure that causes the annular space 48 to flow toward the expansion chamber 62 is increased. As a result, the flow of pressurized air is ensured, and accordingly, the outflow of pressurized air from the annular gap 48 into the expansion chamber 62 is reliably performed with a large flow rate. Then, the outflow pressure of the pressurized air into the expansion chamber 62 is higher than the pressure of the lubricating oil in the expansion chamber 62 opened to the atmosphere, so that the inflow of the lubricating oil from the expansion chamber 62 to the annular gap 48 is prevented. It is reliably avoided that the lubricating oil passes through the annular gap 48 and leaks to the outside without generating heat. Since this is performed in a non-contact manner that does not cause rotational friction, heat generation and wear do not occur.

  Thereby, in the spindle device 10 in which the arrangement portion of the sliding bearing member 36 is immersed in the lubricating oil, the lubricating oil is surely leaked out of the housing assembly 12 without generating heat or wearing.

  Further, since the pressurized air uniformly flows out from the annular passage 68 to the entire area of the annular gap 48, it is more reliably avoided that the lubricating oil passes through the annular gap 48 and leaks to the outside. Further, since the expansion chamber 62 is a space expanded from the annular gap 48, the compressed air flows out from the annular gap 48 to the expansion chamber 62 well. This improves the effect of preventing the lubricating oil in the expansion chamber 62 from leaking outside through the annular gap 48.

  In the unlikely event that the lubricating oil leaks to the front side from the annular gap 48, a part of the pressurized air flows from the annular passage 68 to the front side (the side away from the expansion chamber 62) from the annular passage 68, thereby causing the air seal 72. By being configured, the flow is blocked, and the lubricating oil does not leak from the annular gap 48 to the outside. Thereby, the fail safe effect is acquired.

  Although the present invention has been described above with reference to preferred embodiments thereof, the present invention is not limited to such embodiments and can be deviated from the spirit of the present invention, as will be readily understood by those skilled in the art. It is possible to change appropriately within the range not to be. For example, the outflow of the pressurized air to the annular gap 48 may be performed by an air passage constituting member different from the partition wall 18A because the partition wall 18A is separated from the sliding bearing member 36 (front side). Further, forced oil draining may be performed by connecting oil draining pumps to the oil draining passages 75 and 76. The oil retaining ring 50 may be fixed to the outer periphery of the main shaft 24 instead of the inner periphery of the front housing member 14. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Main shaft apparatus 12 Housing assembly 14 Front housing member 16 Rear housing member 18 Front end member 18A Bulkhead 20 Rear end member 22 Internal space 24 Main shaft 26 Sliding bearing device 30 Rolling bearing device 32 Bearing case 34 Tapered hole 36 Sliding bearing member 36A Thickness Meat part 36B Thin part 38 Center hole 40 Annular gap 42 Pressure ring 46 Opening 48 Annular gap 50 Oil retaining ring 52 Oil supply passage 66 Radial passage 68 Annular passage 70 Air passage 72 Air seal 74 Exhaust passage 75 Exhaust passage 78 Discharge passage 80 Opening 82 Annular gap 84 Air passage

Claims (5)

A spindle device having a spindle, a sliding bearing member for supporting a journal portion of the spindle, and a housing for housing the spindle and the sliding bearing member, wherein the sliding bearing member is immersed in lubricating oil;
A partition wall that includes an opening that surrounds the extension portion of the main shaft that extends from the slide bearing member, and that defines an annular gap with the outer periphery of the main shaft;
An air passage that is defined on a side of the partition wall that is separated from the sliding bearing member, communicates with the annular gap, and is supplied with pressurized air;
A spindle device having an exhaust passage that opens between the sliding bearing member and the partition wall to the outside of the housing.   The said partition consists of a part of said housing, The said air passage includes the annular channel | path which is connected to the radial direction channel | path provided in the said housing and this radial direction channel | path, and surrounds the said main axis | shaft. Spindle device.   The main spindle device according to claim 1 or 2, wherein a labyrinth seal is formed on a side further away from the slide bearing member than an air passage.   The main spindle device according to any one of claims 1 to 3, wherein an expansion chamber is defined that is radially extended between the sliding bearing member and the partition wall facing the sliding bearing member. .   An oil retaining ring for narrowing a gap between the inner periphery of the housing and the outer periphery of the main shaft is provided on the end side away from the partition wall of the sliding bearing member, either the inner periphery of the housing or the outer periphery of the main shaft. 5. The lubricating oil supply passage according to claim 1, wherein the lubricating oil supply passage is attached to one side in a non-contact state with respect to the other, and supplies lubricating oil on the sliding bearing member side from the oil retaining ring. Spindle device.

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