JP3243635B2 - Hydrostatic bearing structure for rotary tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool such as a cylindrical grinder, a surface grinder, and a milling machine, and more particularly, to a rotary tool used for a spindle bearing of a machine tool requiring high precision, high rigidity and high speed machining. The present invention relates to a hydrostatic bearing structure.

[0002]

2. Description of the Related Art Conventionally, as a bearing structure for a rotary tool of this type, in most cases, a rotary shaft on which the rotary tool is mounted is mounted in a cantilevered state by a bearing housing arranged at one side of the rotary tool. The structure is adopted.

[0003] In this cantilever bearing structure, one end of the rotating shaft is released, and the tool can be easily changed from one end of the rotating shaft.

[0004]

However, in this type of cantilever bearing structure, the position of the rotating tool in the direction of the rotating axis is displaced with the elapse of machining time due to thermal expansion of the rotating shaft caused by bearing heat. Due to the displacement of the tool, the machining dimensions are deviated, the rigidity in the radial direction is low, and the machining speed and machining accuracy are likely to be limited.In the case of a cantilevered hydrostatic bearing using air, air However, it is difficult to secure the rigidity due to the compressibility and is not suitable for high-speed machining with a large load.

[0005]

In order to solve the above-mentioned problems, the present invention basically employs a double-supported hydrostatic bearing structure. There, in a hydrostatic bearing structure for a rotating tool capable of bearing a rotating shaft to which a rotating tool is mounted in a bearing housing having a hydrostatic bearing structure arranged on both left and right positions of the rotating tool in a double-supported state, each hydrostatic bearing structure disposed on the left and right positions on both sides of the rotary tool configured mutually symmetrically structured around the mounting position of the rotary tool, the rotary shaft is the rotating
A pair of tools located on both left and right sides of the tool
Hydrostatic shaft for rotary tools , characterized by comprising a split rotary shaft
In the receiving structure . Here, to configure the respective hydrostatic bearing structures disposed on both left and right sides of the rotary tool in a mutually symmetrical structure with respect to the mounting position of the rotary tool means, for example, the bearing surface shape of these bearings, Are substantially symmetrical with respect to each other from the mounting position, whereby the displacement of the rotary tool in the rotation axis direction due to thermal expansion can be substantially suppressed.

[0006] Also, the invention described in claim 2, the peripheral flange portion provided at each right and left end portions of each divided rotary shaft, respectively constitute a thrust hydrostatic bearing structure by axial inner surface of the peripheral flange portion,
The thrust hydrostatic bearing structure has a symmetrical structure with respect to each other about the mounting position of the rotary tool. Here, when the thrust hydrostatic bearing structure is configured to be mutually symmetrical with respect to the mounting position of the rotating tool, for example, the bearing surface shape of these bearings, the distance from the mounting position of the rotating tool, and the like are substantially mutually different. This is a structure which is substantially symmetrical and can thereby substantially suppress the displacement of the rotary tool in the rotation axis direction due to thermal expansion.

According to a third aspect of the present invention, a pair of mounting members capable of sandwiching and holding the rotary tool are provided on a peripheral flange provided at an inner end of the divided rotary shaft on the rotary tool side. It is characterized by being configured to be detachably attached and configured so that a peripheral flange portion provided at an outer end portion of each of the divided rotary shafts is detachably provided with respect to the divided rotary shaft, respectively,
The invention according to claim 4 is characterized in that a joint structure using an aerostatic pressure is provided between the one of the divided rotation shafts and a drive shaft for driving the divided rotation shafts. The invention according to claim 5 is characterized in that a feed hole capable of feeding cooling water or air whose temperature is controlled is formed in each of the divided rotary shafts.

[0008]

1 to 10 show an embodiment of the present invention. FIGS. 1 to 7 show a first embodiment, and FIGS. 8 to 10 show a second embodiment.

In the first embodiment shown in FIGS. 1 to 7, the present invention is applied to an aerostatic bearing. Reference numeral 1 denotes a rotary tool, in this case, a grinding wheel. The rotary tool 1 is mounted on a rotary shaft 2; The rotating shaft 2 is supported in a double-supported state by a pair of bearing housings 3 having a hydrostatic bearing structure M.

Each of the hydrostatic bearing structures M and M arranged on both left and right sides of the rotary tool 1 are configured to be symmetrical with respect to each other with respect to the mounting position K of the rotary tool 1, that is, these static pressures The bearing surface shape of the bearing portion of the bearing structure MM, the distance from the mounting position K of the rotary tool 1, and the like are substantially symmetric with each other. It is configured to be able to substantially suppress positional displacement.

In this case, the rotary shaft 2 is composed of a pair of split rotary shafts 2a, 2a disposed at both left and right positions in the direction of the rotary axis O of the rotary tool 1. In this case, the split rotary shaft 2a
2a, peripheral flanges 4, 4 and 5.5 are provided at both left and right ends, and the axially inner surface of the peripheral flanges 4, 4, 5.5, 5 constitutes a thrust hydrostatic bearing structure N. The respective thrust hydrostatic bearing structures NN arranged on the left and right sides of the rotary tool 1 are configured to be symmetrical with respect to each other about the mounting position K of the rotary tool 1, that is, these thrust hydrostatic bearings The bearing surface shape of the bearing portion of the structure NN, the distance from the mounting position K of the rotary tool 1 and the like are substantially symmetrical with each other, whereby the position of the rotary tool 1 in the direction of the rotation axis O accompanying thermal expansion is obtained. The structure is such that the displacement can be substantially suppressed.

Further, in this case, a pair of mounting members 6 which can clamp and hold the rotary tool 1 on peripheral flanges 5 and 5 provided at the inner end of the rotary tool 1 on the rotary tool 1 side of each of the divided rotary shafts 2a. 7 are detachably mounted, and the peripheral flanges 4, 4 provided at the outer ends of the divided rotary shafts 2a, 2a are connected to the divided rotary shafts 2a, 2a.
2a are provided detachably.

More specifically, in this case, the rotary tool 1 is sandwiched between a mounting member 6 and a mounting member 7 that can be fitted thereto, and is held by a plurality of bolts 8 to hold the rotary tool 1. The peripheral flanges 5 are detachably attached to the respective inner end portions by a plurality of bolts 9 and the divided rotary shaft 2
A peripheral flange portion 4 is detachably attached to each outer end of the shafts 2a and 2a by a plurality of bolts 10.
The peripheral flanges 5.5 attached to the respective inner ends of a are attached to the mounting members 6 and 7 with a plurality of bolts 11.

Further, in this case, the bearing housing 3 comprises a square block-shaped housing 3a attached to the bed B and two left and right cylindrical bearing bodies 3b, 3b. The bodies 3b, 3b are opposed to each other by a distance ring 3c, and a hydrostatic bearing structure M is formed between the inner peripheral surface of each of the bearing bodies 3b, 3b and the outer peripheral surface of the divided rotary shaft 2a. A thrust hydrostatic bearing structure N is formed between both outer end surfaces of the outer flange 3b and the inner surfaces of the circumferential flanges 4 and 5 in the axial direction, and the cover members 12 are provided on the inner and outer surfaces of the housing 3a by a plurality of bolts 13. It is configured by mounting.

In this case, the hydrostatic bearing structure M and the thrust hydrostatic bearing structure N form a supply path 14 connected to an unillustrated air pressure source in the bearing housing 3 and connect the supply path 14 to the bearing body 3b. A plurality of radially arranged nozzles E and bearing bodies 3b connected to a bearing gap D between the inner peripheral surface and the outer peripheral surface of the divided rotary shaft 2a.
3b is branched and connected to a plurality of nozzles S connected to a thrust gap G between each outer surface of the outer ring 3b and the inner surface in the axial direction of the peripheral flange portion 4, 4, 5, 5; 3b, the discharge path 3 connecting the bearing gap D and the thrust gap G to the outside via the small hole of the distance ring 3c and the like.
d is formed.

Further, in this case, tapered tapered surfaces 5a are formed on peripheral flanges 5 formed at respective inner ends of the divided rotary shafts 2a, while the inner peripheral surface of the mounting member 6 is formed. The tapered surfaces 5a, 5a and the tapered surfaces 6a are formed so as to be fitted to the tapered surfaces 5a, 5a.
And the inner surfaces 5b, 5b of the peripheral flanges 5, 5 are connected to the outer surfaces of the fitting members 6, 7 and the inner surfaces 5b, 5b. An elastic collar 15 made of hard rubber or the like is interposed therebetween.

In this case, the one of the divided rotary shafts 3a
A drive shaft 16 driven by a rotary drive source (not shown) is disposed at a side position by a bearing 17, and a joint structure F using static air pressure is provided between the divided rotary shaft 3a and the drive shaft 16. are doing.

In the joint structure F, a diametrically concave groove 3g is formed in the divided rotary shaft 3a, and a flat plate-like convex portion 16a that fits into the concave groove 3g is formed in the drive shaft 16; An air passage 16b connected to an air pressure source (not shown) is formed at the center of the air passage, and the air passage 16b is connected to a gap H between the concave groove 3g and the convex portion 16a.

In this case, a feed hole 18 through which temperature-controlled cooling water or air can be fed to the divided rotary shafts 3a, 3a as the rotary shaft 3 and the peripheral flanges 4, 4, 5, 5 is provided. A through cooling passage 19 having a trapezoidal spiral groove shape is formed on the outer peripheral surface of the bearing body 3b as the bearing housing 3, and a through cooling passage 18 and a cooling air source (not shown) The air supply ports 19a and 19b connecting the water source and the discharge unit are formed.

Since the first embodiment of the present invention has the above-described structure, the rotary shaft 2 on which the rotary tool 1 is mounted is provided with a hydrostatic bearing structure MM in which the rotary shaft 2 is disposed at both left and right positions of the rotary tool 1. In the hydrostatic bearing structure for a rotary tool that can be supported in a double-supported state by the housings 3, 3, the respective hydrostatic bearing structures MM arranged on both right and left positions of the rotary tool 1 are mounted on the rotary tool 1. Since they are configured symmetrically to each other about the position K, the rotating shaft 2 rotates and the bearing housing 3
Even if air as a fluid is supplied into the bearing gap D between the rotary tool and the rotary shaft 2 causing thermal expansion due to heat generated by friction with the fluid, the center of the rotary tool 1 is displaced in the axial direction. Can be suppressed, and the position of the rotary tool 1 in the axial direction O can be stabilized accordingly, high-precision machining can be performed, and since the bearing is a double-supported bearing structure, the radial direction and the axial direction of the rotary tool 1 Since the rigidity of the bearing is increased and the static pressure bearing structure M is used, heat generation can be suppressed and high-speed machining can be performed. As a result, high-precision and high-speed machining can be performed.

Also, in this case, the rotating shaft 2 is composed of a pair of divided rotating shafts 2a, 2a arranged at both left and right positions in the direction of the rotating axis of the rotating tool. In this case, a peripheral flange 4 is provided at both left and right ends of the rotary shaft 2.
The thrust hydrostatic bearing structures NN are constituted by the axially inner surfaces of the peripheral flange portions 4. The thrust hydrostatic bearing structures NN are mutually reciprocated about the mounting position K of the rotary tool 1. , The axial and radial loads can be received by the hydrostatic bearing structures M and M and the thrust hydrostatic bearing structures N and N, and the direction from the rotary tool 1 to the outside. , The axial rigidity can be increased accordingly, and the thrust gap G is widened even if the rotary shaft 2 expands, so that interference with the bearing smooth surface can be prevented. In this case, peripheral flanges 4, 4, 5.5, 5 are provided at both left and right ends of each of the divided rotary shafts 2a, 2a, and thrust hydrostatic bearings are respectively provided by inner surfaces of the peripheral flanges 4, 4, 5.5, 5 in the axial direction. Structure N ・ N ・ N
N, and the thrust hydrostatic bearing structure N, N, N, N is configured to be mutually symmetrical with respect to the mounting position K of the rotary tool 1, so that axial loads are received on four sides. The rigidity in the axial direction can be further increased by the four-sided constraint.

In this case, each of the divided rotary shafts 2a
A pair of mounting members 6 and 7 capable of holding and holding the rotary tool 1 on peripheral flanges 5 and 5 provided at the inner end of the rotary tool 1 on the side of the rotary tool 1.
And each of the divided rotary shafts 2a
Since the peripheral flanges 4 provided at the outer ends of the 2a are detachably provided to the divided rotary shafts 2a, respectively, the rotary tool 1, the divided rotary shafts 2a, 2a, It can be divided into a peripheral portion 4, 4, 5, 5 and a mounting member 6, 7, especially in this case, the tapered surfaces 5a, 5a and the tapered surfaces 6
a and the inner surfaces 5b and 5b of the peripheral flanges 5 and 5 have a two-sided constrained connection structure L, so that high assembly accuracy and high rigidity can be achieved. In this case, the rotary tool 1 can be replaced without disassembling the bearing portion. In this case, the rotary shaft 2 and the drive shaft 16 for driving the rotary shaft 2 can be replaced.
, The joint structure F using the static air pressure is provided, so that the heat propagation from the drive shaft 16 side to the rotary shaft 2 and the bearing body 3 due to the generation of rotational vibration and heat generation can be suppressed. Also, in this case, since the rotary shaft 3 is provided with a feed hole 18 capable of feeding cooling water or air whose temperature is controlled,
The heat generation phenomenon of the rotating shaft 2 can be suppressed. In this case, since the passage cooling passage 19 through which the cooling air and the cooling water pass is formed in the bearing housing 3, the heat generation phenomenon of the bearing housing 3 is formed. Can be suppressed, high-precision, high-rigidity, and high-speed machining can be performed, and machining workability can be improved.

In the second embodiment shown in FIGS. 8 to 10, the present invention is applied to a hydrostatic bearing. The same reference numerals are given to the same parts as those in the first embodiment, and the description will be omitted. Since the static pressure bearing structure M and the thrust static pressure bearing structure N are formed by hydraulic pressure, unlike air, the pressure oil fed into the bearing gap D and the thrust gap G is discharged through the discharge path 3d. In order to return to the inside of the tank (not shown), a plurality of passage lateral grooves 3e extending in the axial direction are formed on the inner peripheral surface of the bearing body 3b, and a passage longitudinal groove 3f is formed on the outer end surface thereof. In addition, in order to make the oil fed into the bearing gap D and the thrust gap G into a static pressure state, diffusion recesses 3h and 3k are respectively formed on the inner peripheral surface and each outer surface of the bearing bodies 3b. The labyrinth structure Q is adopted between 3 and the peripheral collars 4 Forms.

Since the second embodiment has the above-described configuration, the same operation and effect as those of the first embodiment can be obtained, and high-load machining can be performed by static oil pressure.

It should be noted that the present invention is not limited to the structure shown in the above-described embodiment. For example, the hydrostatic bearing structure M and the thrust bearing structure N are designed by appropriately changing the design. The bearing surface of the hydrostatic bearing structure M that receives a load at the same time may be formed in a tapered shape in which the bearing surfaces are c-shaped, and the rotary tool is not limited to a grinding wheel, and may be applied to a milling cutter or the like. Can be.

[0026]

As described above, according to the first aspect of the present invention, there is provided a bearing housing having a hydrostatic bearing structure in which a rotary shaft on which a rotary tool is mounted is disposed at both left and right positions of the rotary tool. In a hydrostatic bearing structure for a rotating tool that can be supported in a double-supported state by a body, the respective hydrostatic bearing structures disposed on the left and right sides of the rotating tool are mutually symmetrical with respect to the mounting position of the rotating tool. Even if the rotating shaft rotates and the fluid is fed into the bearing gap with the bearing housing and the heat generated by friction with the fluid causes the rotating shaft to thermally expand, the rotating tool Of the rotating tool can be suppressed in the axial direction, the position of the rotating tool in the axial direction can be stabilized accordingly, high-precision machining becomes possible, and the rotating bearing structure is used. Tool radial and axis It is possible to increase the rigidity of the direction, further from a hydrostatic bearing structure, high speed processing becomes possible with heat generation can be suppressed, it is possible to turn the high accuracy and high-speed machining, furthermore, the rotating shaft is the rotating Tool
A pair of split rotations arranged at both left and right positions in the rotation axis direction
Since it is composed of the turning shaft, the assembling work becomes easy.

In the invention according to claim 2,
Peripheral flanges are provided at both left and right ends of each of the divided rotary shafts, and a thrust hydrostatic bearing structure is constituted by the axially inner surfaces of the peripheral flanges, respectively. Since it has a symmetrical structure, it can receive both axial and radial loads with the hydrostatic bearing structure and the thrust hydrostatic bearing structure, and can apply static pressure in the direction outward from the rotating tool. Therefore, the axial rigidity can be increased by that much, and the thrust gap tends to widen even if the rotating shaft expands, so it is possible to prevent interference with the bearing smooth surface and to receive the axial load on all four sides. The rigidity in the axial direction can be further increased by the four-sided constraint.

According to the third aspect of the present invention, a pair of mounting members capable of holding and holding the rotary tool on a peripheral flange portion provided at an inner end of the divided rotary shaft on the rotary tool side. Since the members are detachably attached and the peripheral flanges provided at the outer ends of the respective divided rotary shafts are provided so as to be detachable with respect to the divided rotary shaft, respectively, the rotating tool, the divided rotary shaft, Peripheral part, can be divided into mounting members, rotating tools can be replaced without disassembling the bearing part,
Further, in the invention described in claim 4, provided with a joint structure using the air static pressure between the drive shaft for driving the divided rotary shaft and one of the split times <br/> rotating shaft above structure Therefore, it is possible to suppress the transmission of the rotational vibration and heat generated from the drive shaft side to the rotary shaft and the bearing body, and in the invention according to claim 5 , each of the divided rotary shafts Forming a feed hole that can supply cooling water or air whose temperature is controlled to a minimum, can suppress the heat generation phenomenon of the rotating shaft, and enable higher precision, higher rigidity, and higher speed processing. Workability can be improved.

As described above, the intended purpose can be sufficiently achieved.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the first embodiment of the present invention.

FIG. 3 is an overall side view of the first embodiment of the present invention.

FIG. 4 is a cross-sectional view of the first embodiment of the present invention.

FIG. 5 is a partially exploded perspective view of one side of the first embodiment of the present invention.

FIG. 6 is a partially exploded perspective view of one side of the first embodiment of the present invention.

FIG. 7 is a basic explanatory diagram of the first embodiment of the present invention.

FIG. 8 is an overall sectional view of a second embodiment of the present invention.

FIG. 9 is a partially enlarged sectional view on one side of a second embodiment of the present invention.

FIG. 10 is a partial cross-sectional view of the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary tool 2 Rotating shaft 2a Split rotary shaft 3 Bearing housing 4 Peripheral flange 5 Peripheral flange 6 Mounting member 7 Mounting member 16 Drive shaft 18 Feeding hole 19 Passing cooling path K Mounting position M Hydrostatic bearing structure N Thrust static Pressure bearing structure F Joint structure

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-134667 (JP, A) JP-A-3-292414 (JP, A) Jpn. Field (Int.Cl. ⁷ , DB name) F16C 32/00-32/06 B24B 41/00-51/00

Claims (5)

(57) [Claims] 1. A hydrostatic bearing structure for a rotary tool in which a rotary shaft on which a rotary tool is mounted can be supported in a double-supported state by a bearing housing having a hydrostatic bearing structure disposed on both left and right positions of the rotary tool. , each hydrostatic bearing structure disposed on the left and right positions on both sides of the rotary tool configured mutually symmetrically structured around the mounting position of the rotary tool, the rotary shaft upper
It is located on the left and right sides of the rotating tool in the direction of the rotation axis.
A hydrostatic bearing structure for a rotary tool, comprising a pair of split rotary shafts . 2. A peripheral flange portion is provided at each of the left and right ends of each of the divided rotary shafts, and an axial inner surface of the peripheral flange portion constitutes a thrust hydrostatic bearing structure. 2. The hydrostatic bearing structure for a rotary tool according to claim 1 , wherein the hydrostatic bearing structure is configured to be symmetrical to each other with respect to a mounting position of the tool. 3. A pair of mounting members capable of holding and holding the rotary tool are detachably attached to a peripheral flange provided at an inner end of the rotary shaft on the rotary tool side of each of the split rotary shafts. 3. The hydrostatic bearing structure for a rotary tool according to claim 2, wherein a peripheral flange portion provided at an outer end of the rotary shaft is detachably provided to each of the divided rotary shafts. 4. A rotary tool according to claim 1, characterized by being configured to provide a joint structure using the air static pressure between the drive shaft for driving the said one divided rotary shaft and the divided rotary shaft Hydrostatic bearing structure. 5. The hydrostatic bearing structure for a rotary tool according to claim 1, wherein a feed hole capable of feeding cooling water or air whose temperature is controlled is formed in each of said divided rotary shafts.