JP6791080B2 - Manufacturing method of hydrostatic fluid bearing - Google Patents

Description

The present invention relates to a method for manufacturing a hydrostatic fluid bearing, and more particularly to a method for manufacturing a hydrostatic fluid bearing in which a shaft is rotationally supported by fluid static pressure in a non-contact state.

Conventionally, a hydrostatic fluid bearing which is arranged between a housing (not shown) and a shaft and rotationally supports the shaft in a non-contact state by hydrostatic pressure has been provided. For example, Patent Document 1 includes a shaft and a bearing body provided with a bearing surface facing the shaft via a bearing gap, and a gas pressurized in the bearing gap is applied to the bearing surface. A hydrostatic gas bearing that rotatably supports the shaft by opening a plurality of bearings in the circumferential direction around the rotation axis of the shaft and guiding the bearing through a slot throttle extending along the circumferential direction is described. There is.

The conventional slot drawing type hydrostatic fluid bearing has a structure in which a slot drawing with a gap of several tens of μm is arranged on the central circumference of the bearing surface. The slot throttles for supplying fluid may be annular or may be arranged at equal intervals as in Patent Document 1. The fluid supplied from the slot throttle flows into the bearing gap and then is released to the atmosphere. The fluid pressure supplied from the slot throttle gives rigidity to the bearing, and the characteristics change depending on the shape of the slot throttle and its arrangement. The pressure of the fluid flowing out of this throttle supports loads such as shaft mass and centrifugal force during rotation. When supporting a large load with this bearing, it was necessary to increase the bearing diameter and the fluid supply pressure.

Further, in the conventional hydrostatic fluid bearing, since the slot throttle is arranged at the center of the bearing surface in the axial direction, when the load during rotation is biased with respect to the axial direction of the bearing (hereinafter referred to as eccentric load), the bearing surface. There was a high probability of contact at the edges and a high probability of damage. Further, since the conventional fluid bearing mainly uses a metal material, there is a problem that if the shaft and the bearing come into contact with each other during high-speed rotation, damage such as seizure occurs. In order to reduce this, the bearing surface is coated to reduce damage, but the unit price of the bearing is high because it is expensive.

Patent Document 2 discloses a hydrostatic fluid bearing in which radial slot throttles extending along the circumferential direction are provided at two locations separated in the axial direction, but it is configured by combining a large number of complicated parts. Because of this, the cost is high.

Therefore, as described in Patent Document 3, the applicant of the present application comprises a first member and a second member made of synthetic resin, which are combined to form a cylindrical bearing body, and the first member and the second member. Each has a fluid surface extending in the axial direction and the radial direction, and a groove-shaped slot drawing extending in the axial direction of the shaft is formed between the fluid surfaces facing each other when the first member and the second member are combined. A hydrostatic fluid bearing was proposed. As a result, a hydrostatic fluid bearing that exhibits high rigidity against an eccentric load on the bearing can be configured with a minimum of two members, and the slot throttle extends in the direction of the tightening force of the bolt that joins the two members. Therefore, it also has a secondary effect that the deformation of the member has almost no effect on the groove width of the slot throttle.

JP-A-2009-09196 Japanese Unexamined Patent Publication No. 2003-0745555 Japanese Unexamined Patent Publication No. 2015-175484

However, the hydrostatic fluid bearing made of synthetic resin described in Patent Document 3 is provided with a dowel and an engaging hole for positioning at the time of joining the two members, but due to the influence of the creation accuracy of the dowel and the engaging hole. It was difficult to set the assembly accuracy of the two members in μm units, that is, it was difficult to specify the groove width of the slot in μm units. In particular, when having a plurality of slots, it has been difficult to make all the groove widths uniform. However, conventionally, a method of securing a gap with a member such as a spacer has been used, but there has been no method of making the groove-shaped slots arranged radially have a uniform width.

Therefore, in view of the above situation, the present invention attempts to solve the problem by manufacturing a hydrostatic fluid bearing having a small number of parts, high assembly accuracy, and particularly capable of accurately defining air supply holes that generate fluid pressure. The point is to provide a method.

The present invention constitutes the following method for manufacturing a hydrostatic fluid bearing in order to solve the above-mentioned problems.

(1)
It is provided between the shaft and the housing, and has a bearing surface facing the shaft via a bearing gap, and a plurality of air supply holes opened in the bearing surface and provided around the rotation axis of the shaft. In a method for manufacturing a hydrostatic fluid bearing that rotationally supports the shaft in a non-contact state by guiding a pressurized fluid into the bearing gap through the air supply hole.
A step of fitting at least two members, the first member and the second member, and arranging a plurality of the air supply holes radially between the two members.
The process of inserting the adjusting member into the two or more air supply holes, and
A step of fixing the first member and the second member with the adjusting member adjusting the width of the air supply hole in the circumferential direction.
The step of removing the adjusting member from the air supply hole and
A method for manufacturing a hydrostatic fluid bearing, which comprises.

(2)
The method for manufacturing a hydrostatic fluid bearing according to (1), wherein the step of fixing the first member and the second member is tightening with bolts in a state where the adjusting member is inserted into the air supply hole.

(3)
The air supply hole is a groove-shaped slot, the adjusting member is a plate-shaped member having a known thickness, and the step of fixing the first member and the second member is a state in which the adjusting member is inserted into the air supply hole. The method for manufacturing a hydrostatic fluid bearing according to (1), wherein the air supply holes are tightened with bolts in a direction along the groove direction of the air supply holes.

(4)
Each of the first member and the second member is provided with a plurality of convex portions and concave portions in the circumferential direction which are fitted in a nested manner to form a substantially cylindrical shape, and each of the convex portions of the first member and the second member. The inner peripheral surface of the portion constitutes a part of the bearing surface, and is relatively displaced in the circumferential direction in a state of being in airtight contact with the convex portion of the first member and the convex portion of the second member. A play portion is provided to enable the air supply hole, and the air supply hole is formed between the side opposite to the airtight fitting portion of each convex portion and the convex portion of another member adjacent to the play portion. The method for manufacturing a hydrostatic fluid bearing according to any one of (1) to (3) , wherein an adjusting member having a predetermined thickness is inserted into the air supply hole so that the groove width of the air supply hole can be adjusted .

(5)
The airtight fitting portion is a second barrier portion formed of a cylindrical surface provided on the inner peripheral side of the convex portion of the first member and a second barrier portion formed of a cylindrical surface provided on the outer peripheral side of the convex portion of the second member. The method for manufacturing a hydrostatic fluid bearing according to (4) , wherein the barrier portion is formed by providing a play portion that allows displacement in the circumferential direction in an airtight contact state .

The method for manufacturing a hydrostatic fluid bearing of the present invention as described above has the following effects.

According to the configuration of (1), since the air supply holes are arranged radially, the groove widths of all the air supply holes can be made uniform by putting the adjusting members in all the air supply holes, and the adjusting members can be made uniform. By changing the thickness of the air supply hole groove, it is possible to adjust the width of the air supply hole groove. Further, even with a synthetic resin whose processing accuracy is difficult to obtain, air supply holes can be formed with high accuracy.

According to the configuration of (2), the groove widths of the air supply holes do not shift during the fixing step, and the groove widths of all the air supply holes can be accurately defined.

According to the configuration of (3), the groove width of the groove-shaped slot can be accurately defined, and the bearing rigidity can be increased.

According to the configuration of (4), the number of parts is small, the assembly accuracy is high, the size of the air supply holes can be adjusted to a desired width, especially at the intervals of the play portions, and the nested fitting portion is filled with air. Since it does not circulate, the air pressure released from the air supply holes becomes uniform.

According to the configuration of (5), since air does not flow between the first barrier portion and the second barrier portion, it is possible to prevent the fluid from entering the bearing gap from other than the air supply hole and to prevent the fluid from escaping from the bearing gap to the outside. , The pressure distribution of the fluid can be made uniform. In addition, the play portion can be easily manufactured and can be constructed at low cost.

It is an overall perspective view of the hydrostatic fluid bearing of this invention. Similarly, it is an exploded perspective view of a hydrostatic fluid bearing. It is a perspective view which looked at the 2nd member from the convex part side. It is a top view which looked at the 1st member from the convex side. It is a top view which looked at the 2nd member from the convex side. It is a central sectional view in the radial direction in the state where the 1st member and the 2nd member are fitted. It is a central sectional view in the axial direction in the state where the 1st member and the 2nd member are fitted. It is a perspective view cut at the center in the axial direction in the state where the first member and the second member are fitted. It is sectional drawing which shows the use state of the hydrostatic fluid bearing of this invention. It is a perspective view which shows the state in the process of assembling the hydrostatic fluid bearing of this invention. It is a partially enlarged cross-sectional view of the state where the groove width of the groove-shaped slot (air supply hole) is maximized by using the play part. It is a partially enlarged cross-sectional view of the state in which the groove width is defined by sandwiching an adjustment member in a groove-shaped slot (air supply hole).

Next, the present invention will be described in more detail based on the embodiments shown in the accompanying drawings. 1 is an overall perspective view of the hydrostatic fluid bearing according to the present invention, FIGS. 2 to 8 show the details thereof, FIG. 9 shows a state of use, reference numeral 1 in the figure is a hydrostatic fluid bearing, 2 is a shaft, and 3 Indicates the housing.

As shown in FIGS. 1 and 9, the hydrostatic fluid bearing 1 according to the present invention is arranged between the shaft 2 and the housing 3, and the bearing surface 5 facing the shaft 2 via the bearing gap 4. The shaft is provided with a plurality of air supply holes 6 which are opened in the bearing surface 5 and are provided around the rotation axis of the shaft 2, and a fluid pressurized to the bearing gap 4 is guided through the air supply holes 6. 2 is rotationally supported in a non-contact state. In the present embodiment, the hydrostatic fluid bearing 1 has a cylindrical shape as a whole, and the air supply hole 6 is composed of a groove-shaped slot extending in the axial direction and the radial direction of the shaft 2. The positions of the plurality of air supply holes 6 are preferably rotationally symmetric positions so that isotropic static pressure acts on the shaft 2, particularly at equal intervals in the circumferential direction.

As shown in FIG. 1, the hydrostatic fluid bearing 1 has a cylindrical shape as a whole, preferably has a ratio (L / D) of the bearing length L to the diameter D of the bearing surface 5 of 1 to 4, and is in the axial direction. It has a structure in which eight air supply holes 6 extending in the circumferential direction are arranged (similar to a needle bearing in a mechanical type). The air supply hole 6 extends radially from the bearing surface 5 to the inside of the cylindrical portion and communicates with a supply path 7 provided on the outer peripheral portion of the cylindrical portion. Here, the air supply hole 6 can have a groove-shaped slot extending in the axial direction and the radial direction, a groove-shaped slot extending in the circumferential direction, a circular hole, and the like, but has high rigidity against an unbalanced load on the bearing. Groove-shaped slots that extend in the axial and radial directions are the best because they are effective. The air supply hole 6 formed of the groove-shaped slot has a groove width of 5 to 40 μm, more preferably 20 to 30 μm, and the axial groove length is most preferably a groove shape of 1/2 or more of the bearing length L.

Then, the fluid supplied through the supply path 7 flows into the bearing surface 5 through the eight air supply holes 6, passes through the bearing gap 4, and then is released to the atmosphere. Here, the working fluid may be any fluid such as pressurized air, pressurized nitrogen gas, carbon dioxide gas, etc., as long as it can generate a high pressure. Pressurized air is particularly excellent because it is excellent in cost and the compressor of the factory ancillary equipment can be diverted. The supply path 7 is composed of an annular groove 8 formed on the outer peripheral surface of the cylindrical portion in the circumferential direction and a vertical groove 9 that intersects the annular groove 8 and communicates with the outer peripheral opening of each of the air supply holes 6. Is preferable. Further, as shown in FIGS. 1 and 9, O-ring grooves 10 and 11 are formed on the outer periphery of both ends in the axial direction of the hydrostatic fluid bearing 1 so as to include the supply path 7 inside. The supply path 7 is formed in an airtight state by pressing the O-ring 12 mounted on the O-ring grooves 10 and 11 against the inner peripheral surface of the housing 3. The pressurized fluid is supplied to the supply path 7 through a supply hole (not shown) penetrating the housing 3.

Since it is difficult to manufacture the hydrostatic fluid bearing 1 having the above-mentioned structure by machining, at least two members are combined to form the bearing 1. The constituent material of the hydrostatic fluid bearing 1 may be any metal, synthetic resin, or the like, but the effect of the present invention is more remarkable when it is made of a resin whose processing accuracy is difficult to obtain.

The resins constituting the hydrostatic fluid bearing 1 are polyphenylene sulfide (PPS), polyetherimide (PEI), polyetheretherketone (PEEK), polyimide (PI), polyacetal (POM), polyamide (PA) and phenol resin. , Polyproprene, Polyethylene Anything is acceptable, but PPS is the best in that it has excellent processing accuracy in cutting.

The member constituting the hydrostatic fluid bearing 1 can be formed by cutting or injection molding, but the cutting is the most excellent in terms of processing accuracy. Here, the cutting process includes a case of cutting from a block-shaped material and a case of cutting an intermediate molded product which has been injection-molded into a rough shape in advance.

In the hydrostatic fluid bearing 1 according to the present invention, at least two members are fitted in the axial direction and positioned, and then both members are fixed. The fixing method may be any method such as screwing, bolting, bonding, welding, etc. Bolting is especially good because it is easy to readjust and disassemble even after fixing.

Next, the hydrostatic fluid bearing 1 according to the present invention will be specifically described with reference to the drawings. The hydrostatic fluid bearing 1 of the present embodiment is composed of a first member 21 and a second member 22 that are combined to form a cylindrical bearing body. The first member 21 and the second member 22 have an uneven shape that can be combined in a nested manner from the axial direction.

First, as shown in FIGS. 2 and 4, the first member 21 projects eight convex portions 24 having the same shape on the inner side surface of the annular portion 23 at equal intervals in the circumferential direction and is adjacent to each other. The protrusions 24 and 24 are recesses 25 having the same shape. The end faces of the convex portions 24 of the first member 21 form the same plane, and the convex portions 24 are formed with screw holes 26 that are open to the end faces and extend in the axial direction. The screw hole 26 does not penetrate to the outer surface of the annular portion 23. Further, the O-ring groove 10 is formed on the outer periphery of the annular portion 23. The inner peripheral surface of each convex portion 24 of the first member 21 is a cylindrical surface, and forms a part of the bearing surface 5.

Next, as shown in FIGS. 2, 3 and 5, the second member 22 projects eight convex portions 28 having the same shape on the inner surface of the annular portion 27 at equal intervals in the circumferential direction in the axial direction. However, the adjacent protrusions 28 and 28 are recesses 29 having the same shape. The end faces of the convex portions 28 of the second member 22 form the same plane, and through holes 30 extending in the axial direction are formed in the concave portions 29, respectively, and the through holes 30 are formed on the outer surface of the annular portion 27. A spot facing hole 31 is formed around the surface. Further, the O-ring groove 11 is formed on the outer periphery of the annular portion 27. The inner peripheral surface of each convex portion 28 of the second member 22 is a cylindrical surface, and forms a part of the bearing surface 5.

As shown in FIGS. 1 and 2, the first member 21 and the second member 22 are fitted in a nested manner to form a substantially cylindrical shape, respectively. That is, the convex portion 24 of the first member 21 is fitted into the concave portion 29 of the second member 22, and the convex portion 28 of the second member 22 is nestedly fitted to the concave portion 25 of the first member 21 to complement each other. Have a good relationship. Here, at least three pairs of the convex portion 24 and the concave portion 25 of the first member 21 and the pair of the convex portion 28 and the concave portion 29 of the second member 22 are required, but in the present embodiment, eight pairs are provided. ing.

Further, as shown in FIGS. 2, 3 and 6, the convex portion 24 of the first member 21 and the convex portion 28 of the second member 22 are fitted in an airtight state, and the convex fitting is tightly fitted. As shown in FIGS. 10 and 12, the convex portion 24 of the first member 21 and the convex portion 28 of the second member 22 are airtight in the portion 32 so that the adjusting member 33 can be inserted into the air supply hole 6. A play portion 34 that can be relatively displaced in the circumferential direction is provided in a state of contact. Then , the air supply hole 6 is formed between the side of the convex portion 24 opposite to the airtight fitting portion 32 and the convex portion 28 of another member adjacent thereto, and the convex portion 28 and the airtight fitting portion 32 The air supply hole 6 is formed between the opposite side and the convex portion 24 of another member adjacent thereto. That is, the side surface of the convex portion 24 opposite to the airtight fitting portion 32 is a fluid surface 35 extending in the axial direction and the radial direction, and the side surface of the convex portion 28 opposite to the airtight fitting portion 32 is the axis. The fluid surface 36 extends in the direction and the radial direction, and the air supply hole 6 formed of a groove-shaped slot is formed between the fluid surface 35 of the convex portion 24 and the fluid surface 36 of the convex portion 28.

The airtight fitting portion 32 is provided on the outer peripheral side of the convex portion 28 of the second member 22 and the first barrier portion 37 formed of a cylindrical surface provided on the inner peripheral side of the convex portion 24 of the first member 21. The second barrier portion 38 made of a cylindrical surface is formed by providing a play portion 34 that allows displacement in the circumferential direction in a state of airtight contact . The first barrier portion 37 and the second barrier portion 38 form an airtight fitting portion 32. The first member 21 and the second member 22 can be relatively displaced in the circumferential direction due to the presence of the play portion 34 in a nested state, whereby the groove width of the air supply hole 6 is widened. Can be adjusted.

The play portion 34 and the barrier portions 37, 38 may have an uneven structure, a step structure, a laminated structure, or the like, but the step structure of the present embodiment is most suitable because it is easy to manufacture and inexpensive. Further, the play width of the play portion 34 may be designed to be longer than the design groove width of the groove-shaped slot because the groove-shaped slot (air supply hole 6) can be adjusted to a desired groove width.

In order to accurately set the groove width of the air supply hole 6 to the design value, first, as shown in FIG. 11, the play portion 34 is in a state where the first member 21 and the second member 22 are nested and fitted. After widening the groove width of the air supply hole 6 by relative rotation using the above, a plate-shaped or sheet-shaped adjusting member 33 having a specified thickness is inserted into the air supply hole 6, and then FIG. As shown in FIG. 1, the first member 21 and the second member 22 are relatively rotated to sandwich the adjusting member 33 in the air supply hole 6, and in that state, the first member 21 and the second member 22 are shown in FIG. And, as shown in FIG. 10, the bolt 40 is tightened in the axial direction to fix the stoma. The thickness of the adjusting member 33 is in the range of 5 to 40 μm, more preferably 20 to 30 μm, depending on the groove width of the air supply hole 6, because it exhibits high rigidity against an unbalanced load on the bearing. .. As the shape of the adjusting member 33, a plate-shaped member, a columnar member (pin gauge), a triangular member (taper gauge), or the like is used according to the shape of the air supply hole 6. A plate-shaped member is most suitable because the air supply hole 6 is rectangular, and the plate-shaped member may be a rectangular plate (feeler gauge), a triangular plate, or the like. Since the air supply hole 6 is rectangular, it is most preferable that the shape of the adjusting member 33 is also a rectangular plate.

In the present embodiment, since all the air supply holes 6 are formed radially from the inner peripheral side to the outer peripheral side, it is possible to insert the adjusting member 33 into all the air supply holes 6. Thereby, the groove widths of all the air supply holes 6 can be accurately matched. The adjusting member 33 may be inserted into at least two air supply holes 6 facing each other.

The bolt 39 is inserted through the through hole 30 of the second member 22 and screwed into the screw hole 26 of the first member 21, so that the head of the bolt 39 is buried in the counterbore hole 31. There is. The bolt 39 may be loosely screwed before the adjusting member 33 is inserted into the air supply hole 6, and the diameter of the through hole 30 is sufficiently larger than the shaft portion of the bolt 39, and the play portion 34. Since it is larger than the play width of, there is no problem in setting the groove width of the air supply hole 6 by the adjusting member 33. That is, since the screw hole 26 is formed only in the first member 21 and the screw hole 26 is not formed in the second member, the air supply hole 6 by the adjusting member 33 is increased by the amount of play width of the through hole of the second member. It is possible to set the groove width of. Further, by tightening the bolt 39, the screw hole 26 into which the head of the bolt 39 and the bolt 39 are screwed is attracted in the axial direction, and the first member 21 is sandwiched between the first member 21 and the second member 22. Is firmly fixed.

Summarizing the above, the method for manufacturing a hydrostatic fluid bearing of the present invention includes a step of fitting at least two members, a first member 21 and a second member 22, and arranging a plurality of air supply holes 6 radially between the two members. The first member 21 and the second member 22 are fixed in a step of inserting the adjusting member 33 into the two or more air supply holes 6 and in a state where the adjusting member 33 adjusts the width of the air supply hole 6 in the circumferential direction. This includes a step of removing the adjusting member 33 from the air supply hole 6.

Here, the step of fixing the first member 21 and the second member 22 is tightening with bolts 39 with the adjusting member 33 inserted in the air supply hole 6. Specifically, the air supply hole 6 is a groove-shaped slot, the adjusting member 33 is a plate-shaped member having a known thickness, and the step of fixing the first member 21 and the second member 22 is the air supply hole. With the adjusting member 33 inserted in 6, the bolt 39 is used to tighten the air supply hole 6 in the direction along the groove direction.

Since the hydrostatic fluid bearing according to the present invention is used without grease, it is suitable for use in manufacturing equipment for foods and pharmaceuticals. Further, the hydrostatic fluid bearing according to the present invention also has a sealing effect of preventing foreign matter from being mixed into the bearing due to air pressure or the like.

1 Hydrostatic fluid bearing 2 Shaft 3 Housing 4 Bearing gap 5 Bearing surface 6 Air supply hole 7 Supply path 8 Circular groove 9 Vertical groove 10 O-ring groove 11 O-ring groove 12 O-ring 21 1st member 22 2nd member 23 annular part 24 Convex part 25 Concave part 26 Screw hole 27 Circular part 28 Convex part 29 Concave part 30 Through hole 31 Counterbore hole 32 Airtight fitting part 33 Adjusting member 34 Play part 35 Fluid surface 36 Fluid surface 37 First barrier part 38 Second barrier part 39 bolt

Claims (5)

It is provided between the shaft and the housing, and has a bearing surface facing the shaft via a bearing gap, and a plurality of air supply holes opened in the bearing surface and provided around the rotation axis of the shaft. In a method for manufacturing a hydrostatic fluid bearing that rotationally supports the shaft in a non-contact state by guiding a pressurized fluid into the bearing gap through the air supply hole.
A step of fitting at least two members, the first member and the second member, and arranging a plurality of the air supply holes radially between the two members.
The process of inserting the adjusting member into the two or more air supply holes, and
A step of fixing the first member and the second member with the adjusting member adjusting the width of the air supply hole in the circumferential direction.
The step of removing the adjusting member from the air supply hole and
A method for manufacturing a hydrostatic fluid bearing, which comprises. The method for manufacturing a hydrostatic fluid bearing according to claim 1, wherein the step of fixing the first member and the second member is tightening with bolts in a state where the adjusting member is inserted into the air supply hole. The air supply hole is a groove-shaped slot, the adjusting member is a plate-shaped member having a known thickness, and the step of fixing the first member and the second member is a state in which the adjusting member is inserted into the air supply hole. The method for manufacturing a hydrostatic fluid bearing according to claim 1, wherein the bolts are used to tighten the air supply holes in a direction along the groove direction. Each of the first member and the second member is provided with a plurality of convex portions and concave portions in the circumferential direction which are fitted in a nested manner to form a substantially cylindrical shape, and each of the convex portions of the first member and the second member. The inner peripheral surface of the portion constitutes a part of the bearing surface, and is relatively displaced in the circumferential direction in a state of being in airtight contact with the convex portion of the first member and the convex portion of the second member. A play portion is provided to enable the air supply hole, and the air supply hole is formed between the side opposite to the airtight fitting portion of each convex portion and the convex portion of another member adjacent to the play portion. The method for manufacturing a hydrostatic fluid bearing according to any one of claims 1 to 3 , wherein an adjusting member having a predetermined thickness is inserted into the air supply hole so that the groove width of the air supply hole can be adjusted . The airtight fitting portion is a second barrier portion formed of a cylindrical surface provided on the inner peripheral side of the convex portion of the first member and a second barrier portion formed of a cylindrical surface provided on the outer peripheral side of the convex portion of the second member. The method for manufacturing a hydrostatic fluid bearing according to claim 4 , wherein the barrier portion is formed by providing a play portion that allows displacement in the circumferential direction in an airtight contact state .

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