JP2006097797A - Porous static pressure gas bearing and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous static pressure gas bearing, if long, for suppressing the heating of air while properly escaping air forming a gas membrane to the outside to avoid its residence and for actualizing the higher-speed movement, particularly, the rotation of a movable body relative to a bearing surface while avoiding heat expansion on the sides of the bearing surface and the movable body, and to provide its manufacturing method. <P>SOLUTION: The porous static pressure gas radial bearing 1 comprises a backing metal 2, porous metal sintered layers 6a, 6b arranged side by side on an inner face 3 of the backing metal 2 with an annular gap 5 therebetween, a supply means 12 for supplying high pressure gas to each of the porous metal sintered layers 6a, 6b, sealing materials 15a, 15ab, 15b integrally joined to end faces 13, 13a, 14, 14b of the porous meal sintered layers 6a, 6b, a radial through-hole 16 provided in the sealing material 15ab, and a through-hole 17 for communicating the through-hole 16 with the outside of the backing metal 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a porous hydrostatic gas bearing, and more particularly to a porous hydrostatic gas bearing provided with a sintered porous metal layer containing dispersed inorganic substance particles and a method for manufacturing the same.

JP-A-11-158511 JP 2000-346071 A

  Since a static pressure gas bearing is one in which a gas film is formed between a movable body supported by the bearing surface and the movable body is supported movably through the gas film, The pressurized gas bearing, combined with its inherent centering function, does not require lubrication or lubrication in the bearing gap, and does not generate vibration even during high-speed movement, with low friction and low heat generation. Therefore, the movable body can be preferably supported.

  As one of the static pressure gas bearings, a porous static pressure gas bearing (see Patent Document 1) including a back metal and a porous metal sintered layer fixed to the back metal is used. In the gas bearing, in order to increase the utilization efficiency of the high-pressure gas supplied, it is preferable that the high-pressure gas is ejected only from the bearing surface in the porous metal sintered layer.

  In the above porous hydrostatic gas bearing, since the porous metal sintered layer is integrally formed on one side of the back metal, avoid leakage of high-pressure gas from the end surface of the porous metal sintered layer. In other words, the utilization efficiency of the high-pressure gas is reduced.

  In response to this problem, the applicant first fixed the sealing material on the end surface of the porous metal sintered layer so as to cover the end surface and not protrude beyond the bearing surface of the porous metal sintered layer. A porous hydrostatic gas bearing was proposed (see Patent Document 2).

  The porous hydrostatic gas bearing according to this proposal includes a back metal and a porous metal sintered layer fixed to one surface of the back metal, and the end surface of the porous metal sintered layer has the The sealing material is fixed so as to cover the end face of the porous metal sintered layer and not to protrude beyond the bearing surface of the porous metal sintered layer.

  By the way, in the porous static pressure gas bearing, a gas film is formed between the bearing surface and the movable body, and the movable body is supported via the gas film. However, in the relative high-speed rotation of the movable body with respect to the bearing surface. The air in the gas film receives heat at high speed and generates heat. This heat generation causes thermal expansion on the bearing surface side and the movable body side, narrowing the gap between the bearing surface and the movable body, and in the worst case, may cause seizure of the bearing. It becomes a factor which determines the relative movement, for example, the upper limit of rotation. In particular, in the case of a long porous hydrostatic gas bearing that is long in the axial direction, it is not possible to expect much escape of the gas film air to the outside in the axial intermediate portion. Then, it stays there and receives high-speed shearing force over a relatively long time to generate heat, and there is a possibility that the gap between the bearing surface and the movable body there is greatly narrowed.

  Further, in the porous static pressure gas bearing according to the applicant's proposal shown in Patent Document 2, the end surface of the porous metal sintered layer is covered with the end surface of the porous metal sintered layer, and the porous metal sintered material is sintered. The sealing material made of epoxy resin or phenol resin is fixed so as not to protrude beyond the bearing surface of the layer to prevent leakage of high-pressure gas from the end face of the porous metal sintered layer. Since the fixing work of the sealing material made of resin or phenol resin is performed after cutting or grinding the porous metal sintered layer fixed to one surface of the back metal, the porous static pressure according to the proposal In the manufacturing process of the gas bearing, this sealing work process is inevitably added.

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is to allow the air forming the gas film to escape to the outside appropriately so as to avoid the retention even if it is long. A porous hydrostatic gas bearing that can suppress heat generation of air, and thus can avoid thermal expansion on the bearing surface side and the movable body side, thereby enabling faster movement of the movable body relative to the bearing surface, in particular rotation. It is in providing the manufacturing method.

  The other object of the present invention is that without requiring a sealing work step with a sealing material composed of an epoxy resin or a phenol resin after the cutting or grinding of the porous metal sintered layer, Moreover, there is no need to wait for drying or solidification of epoxy resin or phenolic resin, etc., and it is possible to obtain a temporary product by completion of cutting processing or grinding processing to the porous metal sintered layer. An object of the present invention is to provide a porous hydrostatic gas bearing capable of maintaining a reliable sealing of the end face of the sintered metal layer over a long period of time and a method for manufacturing the same.

  The porous hydrostatic gas bearing of the present invention includes a cylindrical back metal made of stainless steel, and at least two porous metal sintered layers juxtaposed on the cylindrical inner surface of the back metal with an annular gap in the axial direction. In order to supply a high pressure gas to each of the porous metal sintered layers, the inner surface of the back metal is formed with an opening on the inner surface side, and the opening on the inner surface side is covered with the porous metal sintered layer. The end of the back metal and the end surface of the porous metal sintered layer in the annular gap are sealed in order to seal the end means of the back metal and the end surface of the porous metal sintered layer in the annular gap. In order to make the through-hole communicate with the outside of the back metal, the sealing material joined integrally, the radial through-hole provided in the sealing material sealing the end face of the porous metal sintered layer in the annular gap And a through hole provided in the back metal.

  According to the porous hydrostatic gas bearing of the present invention, at least two porous metal sintered layers are juxtaposed on the cylindrical inner surface of the back metal with an annular gap in the axial direction to divide the porous metal sintered layer. The through hole in the radial direction is provided in the sealing material that seals the end face of the porous metal sintered layer in the annular gap, and the through hole provided in the back metal is the sealing material. Because the through hole in the radial direction is communicated with the outside of the back metal, even if the porous hydrostatic gas bearing is elongated in the axial direction, it is in the vicinity of the two porous metal sintered layers. The air that forms the gas film can be appropriately released to the outside through the through hole of the sealing material and the through hole of the back metal so as to avoid the retention, and the heat generation of the air in the gas film in the vicinity is suppressed. Therefore, it is possible to avoid thermal expansion on the bearing surface side and the movable body side, and against the bearing surface. Faster movement of the movable body, in particular to allow rotation.

  In a preferred example of the present invention, a bonding layer is formed on the inner surface of the back metal, each porous metal sintered layer is integrally bonded to the inner surface of the back metal via the bonding layer, and each sealing material is The inner surface of the back metal is joined via a joining layer and is made of pure copper. According to the porous hydrostatic gas bearing of such an example, the sealing material made of pure copper on the end face of the porous metal sintered layer Can be used to eliminate leakage of the supply high-pressure gas from the end face, increase the utilization efficiency of the supply high-pressure gas, and not only can form a desired gas film in the bearing gap, but also porous metal. Without requiring a sealing work step with a sealing material composed of an epoxy resin or a phenol resin after the cutting process or grinding process on the sintered layer, and waiting for drying or solidification of the epoxy resin or the phenol resin, etc. No need for porous metal sintering It can be obtained prima facie product with a completion of a cutting or grinding to.

  In the above preferred example, the bonding layer includes two plating layers of a nickel plating layer and a copper plating layer, the nickel plating layer being bonded to the inner surface of the back metal, and the porous metal sintered layer and the sealing layer. The stopper is preferably bonded to the copper plating layer. According to the porous hydrostatic gas bearing of this example, the bonding layer, the sealing material and the porous metal sintered layer formed on the inner surface of the cylindrical back metal Is a metal-to-metal bond, so the bonding force is strong, and the sealing material peels off from the inner surface of the back metal and the end surface of the porous metal sintered layer by the high-pressure gas supplied to the porous metal sintered layer Rather, reliable sealing of the end face of the porous metal sintered layer can be maintained over a long period of time.

  In the present invention, oxygen-free copper or tough pitch copper can be suitably used as pure copper, and the oxygen-free copper or tough pitch copper is partly alloyed and bonded to the end face of the porous metal sintered layer. Therefore, the bonding force between the sealing material and the porous metal sintered layer is high, and as a result, the peeling of the sealing material from the porous metal sintered layer does not occur.

In another example of the present invention, the sintered porous metal layer has 4 wt% or more and 10 wt% or less of tin (Sn), 10 wt% or more and 40 wt% or less of nickel (Ni), 0.1 wt% % To less than 0.5% by weight of phosphorus (P), 2% to 10% by weight of inorganic substance particles, and the balance consisting of copper (Cu). In the sintering process, since the phosphorus component that generates liquid phase Ni ₃ P is 0.1 wt% or more and less than 0.5 wt%, the amount of liquid phase Ni ₃ P generated is reduced. The liquid phase Ni ₃ P does not flow out at the time of sintering, and the amount of liquid phase Ni ₃ P necessary to join the porous metal sintered layer to the bonding layer is obtained, and the porous metal sintering via the bonding layer The bonding force between the layer and the back metal is increased, and the amount of generated liquid phase Ni ₃ P is small, so that cooling (release) is performed after sintering. Since the amount of shrinkage of the porous metal sintered layer during cooling is small, the porous metal fired at each joining surface through the joining layer between the back metal and the porous metal sintered layer due to the shrinkage of the porous metal sintered layer. No delamination occurs.

  In the present invention, the inorganic substance particles dispersed and contained in the porous metal sintered layer are preferably at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Selected and used.

  Such inorganic substance particles dispersed and contained in the grain boundary of the porous metal sintered layer are not themselves plastically deformed by machining, and in addition, the plasticity of the metal part of the base of the porous metal sintered layer By clogging and reducing deformation, clogging of the porous sintered metal layer in machining such as cutting or grinding for forming the bearing surface can be suppressed.

  The method for producing a porous hydrostatic gas bearing according to the present invention comprises preparing a cylindrical backing metal made of stainless steel, and forming at least two annular grooves on the cylindrical inner surface of the backing metal at predetermined intervals in the axial direction. Forming a bonding layer composed of two plating layers, a nickel plating layer bonded to the inner surface of the back metal and a copper plating layer bonded to the nickel plating layer, on the inner surface of the back metal; 4% by weight to 10% by weight tin, 10% by weight to 40% by weight nickel, 0.1% by weight to less than 0.5% by weight phosphorus, and 2% by weight to 10% by weight inorganic The material particles and the balance copper are mixed to form a mixed powder, the mixed powder is loaded into a mold, and a predetermined compacting pressure is applied to form two cylindrical green compacts made of the mixed powder. And at least three annular sealing materials made of pure copper After the step of preparing and press-fitting one sealing material to the inner surface of one end of the back metal via a bonding layer, the inner surface of the back metal is contacted with the one sealing material via the bonding layer. One green compact is press-fitted and then contacted with the end face of one green compact between two annular grooves in the axial direction, and the other sealing material is bonded to the inner surface of the back metal via a bonding layer Press-fit, and contact with the other sealing material to press-fit the other green compact to the inner surface of the back metal via the bonding layer, and contact with the end surface of the other green compact. The step of press-fitting the sealing material remaining on the inner surface of the other end through the bonding layer, and sintering these at a temperature of 800 to 1150 ° C. for 20 to 120 minutes in a reducing atmosphere or vacuum, The step of bonding the green compact to the inner surface of the back metal through the bonding layer simultaneously with the sintering of the body, and after sintering, the bonding layer is inserted into the inner surface of the back metal And a step of cutting or grinding the inner surface of the porous metal sintered layer obtained by sintering the green compact, and the sealing material made of pure copper is used as the back metal A porous hydrostatic gas bearing is manufactured which is bonded to the inner surface of the back metal in the end portion and the annular gap via a bonding layer and integrally bonded to the end surface of the porous metal sintered layer. .

  According to the manufacturing method of the present invention, a joining consisting of two plating layers, a nickel plating layer joined to the inner surface of the backing metal and a copper plating layer joined to the nickel plating layer, on the cylindrical inner surface of the backing metal. After forming a layer and press-fitting one sealing material to the inner surface of one end of the back metal via a bonding layer, the inner surface of the back metal is contacted with tin, nickel Then, one green compact containing phosphorus, inorganic particles and copper is press-fitted through a bonding layer, and then brought into contact with the end face of one green compact between two annular grooves in the axial direction. The other sealing material is press-fitted to the inner surface of the back metal via a bonding layer, and the other green compact is pressed to the inner surface of the back metal via the bonding layer. The sealing material remaining on the inner surface of the other end of the back metal is brought into contact with the end surface of the other green compact through the bonding layer. The backing metal, the sealing material, and the green compact are sintered in a reducing atmosphere or vacuum at a temperature of 800 to 1150 ° C. for 20 to 120 minutes, and the green compact is sintered through the bonding layer simultaneously with the sintering of the green compact. As a result of bonding to the inner surface of the back metal of the body, each end surface of the porous metal sintered layer obtained by firing of the green compact is integrally bonded to the inner surface of the back metal via the bonding layer. Since the sealing material made of pure copper integrally bonded to the copper plating layer of the inner surface of the bonding layer is partly alloyed and integrally bonded with the porous metal sintered layer during sintering, the backing metal of the sealing material The bonding strength between the inner surface of the porous metal sintered layer and the end surface of the porous metal sintered layer is increased, the sealing material does not peel off from the porous metal sintered layer, and the high pressure from each end surface of the porous metal sintered layer. Gas leakage can be eliminated, the utilization efficiency of the supplied high-pressure gas can be increased, and the desired clearance can be provided in the bearing gap. Not only can a film be formed, but it does not require a sealing work step with a sealing material made of epoxy resin or phenol resin after cutting or grinding to the porous metal sintered layer, and epoxy There is no need to wait for the resin or phenol resin to dry or solidify, and the porous metal sintered layer can be cut or ground to complete a temporary product, and then formed on the inner surface of the back metal. The bonding layer, the sealing material, and the porous metal sintered layer are bonded to each other, so that the bonding force is strong, and the sealing material becomes the inner surface of the back metal and the high pressure gas supplied to the porous metal sintered layer. No peeling or the like occurs from the end face of the porous metal sintered layer, it is possible to maintain a reliable sealing of the end face of the porous metal sintered layer over a long period of time, and two porous metal sintered bodies A void that forms a gas film near the interlayer If air is allowed to escape to the outside as appropriate, it is possible to avoid the retention of air in the vicinity of the two porous metal sintered layers and to suppress the heat generation of the air. It is possible to provide a porous hydrostatic gas bearing capable of avoiding thermal expansion on the body side and capable of movement including faster rotation of the movable body with respect to the bearing surface.

  The manufacturing method of the present invention includes a step of forming, in the back metal and other sealing material, a through-hole for escaping air that forms a gas film in the vicinity of two porous metal sintered layers to the outside. However, such a step may be performed after the green compact is fired or after cutting or grinding, and before the step of forming the through hole, it is performed on the inner peripheral surface of another sealing material. There may be provided a step of forming an annular groove. By forming this annular groove, air forming a gas film in the vicinity of the two porous metal sintered layers is passed through the annular groove. Can effectively escape to the outside. Furthermore, in the manufacturing method of the present invention, a back metal having a through hole in the radial direction and other sealing material are prepared, and the through hole in the radial direction of the other sealing material is communicated with the through hole in the radial direction of the back metal. Thus, the step of bringing another sealing material having a through hole in the radial direction into contact with the end face of the one green compact between the two annular grooves in the axial direction and press-fitting to the inner surface of the back metal In this case, if another sealing material having an annular groove on the outer peripheral surface is used, the position of the radial through hole of the back metal and the radial through hole of the other sealing material Matching is easy and preferable.

  In the production method of the present invention, the inorganic substance particles dispersed and contained in the porous metal sintered layer are at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. It should be selected and used.

  According to such a manufacturing method, the inorganic substance particles dispersed and contained in the grain boundaries of the porous metal sintered layer are not themselves plastically deformed by machining, and in addition, the porous metal sintered layer By clogging and reducing the plastic deformation of the metal part of the substrate, clogging of the porous metal sintered layer in machining can be suppressed.

  In the method for producing a porous hydrostatic gas bearing according to the present invention, oxygen-free copper or tough pitch copper may be used as the pure copper forming the sealing material.

  Oxygen-free copper or tough pitch copper is partly alloyed and bonded to the end face of the porous metal sintered layer during sintering, so the bonding force between the sealing material and the porous metal sintered layer is As a result, peeling of the sealing material from the porous metal sintered layer does not occur.

  In the present invention, the supply means may include at least two annular grooves as a groove and a linear groove communicating the two annular grooves in one preferred example, but instead of such a linear groove, Alternatively, holes may be included in addition to the linear grooves.

  According to the present invention, even if it is long, the air forming the gas film can be released to the outside appropriately so as to avoid the retention, and the heat generation of the air can be suppressed. In addition, it is possible to provide a porous hydrostatic gas bearing capable of avoiding thermal expansion on the movable body side and enabling faster movement of the movable body relative to the bearing surface, in particular rotation, and a method for manufacturing the same.

  According to the present invention, the epoxy resin can be used without the need for a sealing work step with a sealing material made of an epoxy resin or a phenol resin after the cutting or grinding of the porous metal sintered layer. Alternatively, it is not necessary to wait for drying or solidification of phenol resin or the like, and the porous metal sintered layer can be obtained by completion of cutting or grinding to the porous metal sintered layer. It is possible to provide a porous hydrostatic gas bearing capable of maintaining a reliable sealing of the end face for a long period of time and a method for manufacturing the same.

  Next, an example of an embodiment of the present invention will be described in more detail based on an example shown in the figure. The present invention is not limited to these examples.

  A porous hydrostatic gas radial bearing 1 as a porous hydrostatic gas bearing of this example shown in FIGS. 1 to 4 includes a cylindrical back metal 2 made of stainless steel that is long with respect to the inner diameter, and a back metal 2. At least two (in this example, two) perforations that are integrally bonded to the cylindrical inner surface 3 via a bonding layer 4 formed on the inner surface 3 and juxtaposed with an annular gap 5 in the axial direction. The inner surface 3 of the back metal 2 is formed with an opening on the inner surface 3 side so as to supply high-pressure gas to each of the sintered metal layers 6a and 6b and the porous sintered metal layers 6a and 6b. 3 side openings are covered with porous metal sintered layers 6a and 6b, respectively, and two annular grooves 7 and 8 arranged at an interval in the axial direction and one annular in the axial direction of the back metal 2 The inner side of the back metal 2 extends in the axial direction from the end surface 10 toward the other annular end surface 9. Are provided on the inner surface 3 of the end of the back metal 2 and the inner surface 3 of the back metal 2 in the annular gap 5 via the bonding layer 4. In order to seal the end faces 13 and 13a and 14 and 14b of the porous metal sintered layers 6a and 6b in the end of the back metal 2 and the annular gap 5, the porous in the end of the back metal 2 and the annular gap 5 is sealed. Three sealing materials 15a, 15ab and 15b integrally joined to the end faces 13 and 13a and 14 and 14b of the sintered metal layers 6a and 6b, and end faces of the porous metal sintered layers 6a and 6b in the annular gap 5 One or more radial holes provided in the sealing material 15ab for sealing 13a and 14b, in this example, one through hole 16 and the back metal 2 and the radial through hole 16 are backed by the back metal Communicating outside of 2 1 or more, in this example, one through-hole 17, and cylindrical inner surfaces of the porous metal sintered layers 6 a and 6 b are used as bearing surfaces 18 a and 18 b, respectively. In addition to the annular grooves 7 and 8 and the hole 11 provided in the back metal 2, an opening is provided at the cylindrical outer surface 19 of the back metal 2 so as to be provided in the back metal 2 and the annular groove 8 through the annular groove 7 and the hole 11. And a high-pressure gas supply hole 20 for supplying a high-pressure gas supply, and the through hole 17 is opened at the outer surface 19 of the back metal 2 and communicated with the outside.

  One end 21 in the axial direction of the hole 11 opened at the annular end surface 10 of the back metal 2 is closed with a stopper 22 made of a knock pin, and the other end 23 in the axial direction of the hole 11 is in front of the annular end surface 9 of the back metal 2. While closed by the back metal 2 itself, it communicates with the hole 20, the hole 11 communicates with the annular groove 8 in the middle thereof, and the hole 20 communicates with the hole 11 and the annular groove 7.

  In the porous hydrostatic gas radial bearing 1, as the stainless steel forming the back metal 2, austenitic stainless steel, martensitic stainless steel or ferritic stainless steel is used. In particular, martensitic stainless steel or ferritic stainless steel having a low chromium (Cr) content is preferable.

  The bonding layer 4 is bonded to the nickel plating layer bonded to the inner surface 3 of the back metal 2, the surface of the nickel plating layer, and the porous metal sintered layers 6a and 6b and the sealing materials 15a, 15ab and 15b It includes two plating layers with a copper plating layer bonded to the substrate. In order to prevent peeling or the like from occurring at the joint between the back metal 2 and the porous metal sintered layers 6a and 6b via the bonding layer 4, to the green compact plating layer forming the porous metal sintered layers 6a and 6b. Depending on the degree of pressure contact, the nickel plating layer has a thickness of 2 μm or more and 20 μm or less, preferably 3 μm or more and 15 μm or less, and the copper plating layer is 10 μm or more and 25 μm or less, preferably 10 μm or more and 20 μm or less. It has the thickness of.

Each of the porous metal sintered layers 6a and 6b is composed of 4 wt% or more and 10 wt% or less tin, 10 wt% or more and 40 wt% or less nickel, and 0.1 wt% or more and less than 0.5 wt%. Phosphorus, 2% by weight or more and 10% by weight or less of inorganic substance particles, and the balance consists of copper. The phosphorus component in the component generates liquid phase Ni ₃ P in the sintering process of the green compact, advances the sintering, and diffuses the nickel component into the bonding layer 4 formed on one surface of the back metal 2. The porous metal sintered layers 6a and 6b obtained by sintering the green compact are firmly integrated.

Moreover, the amount of shrinkage at the time of cooling after sintering of the porous metal sintered layers 6a and 6b can be kept low by making the blending amount of the phosphorus component 0.1 wt% or more and less than 0.5 wt%, No peeling or the like from the bonding layer 4 on the inner surface 3 of the back metal 2 of the porous metal sintered layers 6a and 6b due to the shrinkage of the porous metal sintered layers 6a and 6b. Further, the porosity of the porous metal sintered layers 6a and 6b is increased by reducing the amount of phosphorus component added and the amount of liquid phase Ni ₃ P produced, and the porous metal sintered layers 6a and 6b By reducing the pressure loss of the high-pressure gas flowing through 6b, the air supply pressure ejected to the bearing surfaces 18a and 18b of the porous metal sintered layers 6a and 6b can be relatively increased and the flying height can be increased.

  The inorganic substance particles dispersedly contained in each of the porous metal sintered layers 6a and 6b are made of at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. . These are inorganic substances that do not undergo plastic deformation like many metal materials. When such inorganic substance particles are dispersed and contained in the base (grain boundary) made of tin, nickel, phosphorus and copper of the porous metal sintered layers 6a and 6b, the particles themselves are plastically deformed by machining. In addition, since there is a function of dividing and reducing plastic deformation of the metal portion of the base of the porous metal sintered layers 6a and 6b, clogging of the porous metal sintered layers 6a and 6b in machining is prevented. Can be suppressed. And, the blending amount of these inorganic substance particles is suitably a ratio of 2% by weight to 10% by weight. When the blending amount is less than 2% by weight, the function of dividing and reducing the plastic deformation of the metal parts of the porous metal sintered layers 6a and 6b is not sufficiently exerted, and when the blending amount exceeds 10% by weight, This impairs the sinterability of the porous metal sintered layers 6a and 6b.

  In the annular sealing materials 15a, 15ab, and 15b made of pure copper, the sealing material 15ab is formed on the annular inner peripheral surface 30 and the outer peripheral surface 31 and the inner peripheral surface 30 in addition to the through hole 16. The groove 32 is communicated with the outer peripheral surface 31 side of the sealing material 15ab by the through hole 16, and thus the groove 32 passes through the through hole 16 and the through hole 17. As a result of communicating with the outside of the backing metal 2, air forming a gas film in the vicinity 34a and 34b between the porous metal sintered layers 6a and 6b adjacent to the annular gap 5, that is, in the vicinity 34a and 34b of the annular gap 5 is In addition, it is discharged to the outside of the back metal 2 through the groove 32, the through hole 16 and the through hole 17. An annular groove equivalent to the groove 32 may be formed on the outer peripheral surface 31, and the groove of the outer peripheral surface 31 and the groove 32 may be communicated with each other through the through hole 16. May be dispersed in the sealing material 15ab in the circumferential direction, preferably at equal angular intervals, and the grooves of the outer peripheral surface 31 and the grooves 32 may be communicated with each other through the plurality of through holes 16.

  According to the porous hydrostatic gas radial bearing 1, two porous metal sintered layers 6a and 6b are juxtaposed on the cylindrical inner surface 3 of the back metal 2 with the annular gap 5 interposed therebetween in the axial direction. The bonding layers are divided and the radial through holes 16 are provided in the sealing material 15ab for sealing the end faces 13a and 14b of the porous metal sintered layers 6a and 6b in the annular gap 5. Moreover, since the through hole 17 provided in the back metal 2 allows the radial through hole 16 of the sealing material 15ab to communicate with the outside of the back metal 2, the porous hydrostatic gas bearing 1 is axially arranged. The air forming a gas film in the vicinity 34a and 34b between the two porous metal sintered layers 6a and 6b is allowed to pass through the through-hole 16 of the sealing material 15ab and the through-hole 17 of the back metal 2. To avoid any stagnation through the Thus, the heat generation of the gas film air in the vicinity 34a and 34b can be suppressed, and thus the thermal expansion of the bearing surfaces 18a and 18b and the movable body, for example, the rotating shaft 35 can be avoided. Faster rotation of the rotating shaft 35 relative to the surfaces 18a and 18b can be made possible.

  Further, according to the porous hydrostatic gas radial bearing 1, sealing materials 15a, 15ab and 15b made of pure copper are joined to the end faces 13 and 13a and 14 and 14b of the porous metal sintered layers 6a and 6b, respectively. Therefore, the leakage of the supply high-pressure gas from the end faces 13 and 13a and 14 and 14b can be eliminated, the utilization efficiency of the supply high-pressure gas can be increased, and a desired gas film can be formed in the bearing gap 36. There is no need for a sealing work step with a sealing material made of epoxy resin or phenol resin after the cutting or grinding of porous metal sintered layers 6a and 6b, and epoxy resin or phenol resin, etc. There is no need to wait for drying and solidification of the porous metal, and it is possible to obtain a temporary product by cutting or grinding the porous metal sintered layers 6a and 6b. In addition, the bonding layer 4 formed on the inner surface 3 of the back metal 2, the sealing materials 15 a, 15 ab and 15 b and the porous metal sintered layers 6 a and 6 b are bonded to each other, so that the bonding force is strong and porous. The sealing materials 15a, 15ab and 15b are peeled off from the inner surface 3 of the back metal 2 and the end surfaces 13 and 13a and 14 and 14b of the porous metal sintered layers 6a and 6b by the high pressure gas supplied to the metal sintered layers 6a and 6b. The end surfaces 13 and 13a and 14 and 14b of the porous metal sintered layers 6a and 6b can be reliably sealed for a long time.

  Next, the manufacturing method of the porous static pressure gas radial bearing 1 will be described.

  A cylindrical back metal 2 that is long with respect to the inner diameter of the austenitic stainless steel, martensitic stainless steel, or ferritic stainless steel and does not have the through-hole 17 is prepared. Two annular grooves 7 and 8 are formed at equal intervals in the axial direction, and the annular groove 7 extends in the axial direction from one annular end face 10 in the axial direction of the backing metal 2 toward the other annular end face 9 in the backing metal 2. And 8 are opened at the cylindrical outer surface 19 in the radial direction of the back metal 2 and the diameter of the inner surface of the back metal 2 from the outer surface 19 of the back metal 2 toward the hole 11 for mutual communication. A hole 20 for supplying high-pressure gas extending in the direction is formed, and one end 21 of the hole 11 is closed by a plug 22 made of a knock pin.

  Nickel plating layer having a thickness of 2 to 20 μm, preferably 3 to 15 μm, on the inner surface 3 excluding these annular grooves 7 and 8 of the back metal 2 in which the holes 11 and 20 closed by the stoppers 22 and the annular grooves 7 and 8 are formed. A copper plating layer having a thickness of 10 to 25 μm, preferably 10 to 20 μm is formed on the surface of the nickel plating layer, and the inner surface 3 of the back metal 2 is removed from the inner surface 3 excluding the annular grooves 7 and 8. A bonding layer 4 composed of two plating layers, a nickel plating layer bonded to 3 and a copper plating layer bonded to the nickel plating layer, and bonding the back metal 2 and the porous metal sintered layers 6a and 6b. Form.

  4 to 10% by weight of atomized tin powder passing through a 250-mesh sieve, 10 to 40% by weight of electrolytic nickel powder passing through a 250-mesh sieve, and copper phosphorous ( Phosphorus 14.5%) Powder 0.7 wt% or more and less than 3.4 wt%, inorganic substance particles 2 wt% or more and 10 wt% or less passing through 150 mesh screen, electrolytic copper passing through 150 mesh screen The remaining powder is mixed with a mixer to prepare a mixed powder.

  As the inorganic substance particles, those composed of at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide and silicon carbide are suitable.

This mixed powder is loaded into a mold and compression molded at a molding pressure of 3 ton / cm ^{2 to} 7 ton / cm ² to produce two cylindrical compacts.

  Two annular sealing materials 15a and 15b made of pure copper and a sealing material 15ab made of pure copper having no through hole 16 and groove 32 are prepared. As pure copper for forming the sealing materials 15a, 15ab and 15b, one or two types of oxygen-free copper specified by JIS-H-2123 or a tough pitch type copper also specified by JIS-H-2123 Is preferably used.

  One of the inner surfaces 3 of one end of the cylindrical back metal 2 formed with two plating layers (joining layer 4) composed of a nickel plating layer and a copper plating layer is provided via the plating layer (joining layer 4). After the annular sealing material 15a is press-fitted and fitted, one green compact is pressed into the cylindrical back metal 2, and the green compact is brought into contact with the sealing material 15a so that a plating layer is formed on the inner surface 3 of the back metal 2. Then, the sealing material 15ab is brought into contact with the end face of the one green compact between the two annular grooves 7 and 8 in the axial direction, and the sealing material 15ab is brought into contact with the inner surface of the back metal 2. 3 is press-fitted to the plate 3 through the plating layer (joining layer 4), and the other green compact is pressed into the cylindrical back metal 2 so that the other green compact is brought into contact with the sealing material 15ab. 2 is press-fitted to the inner surface 3 of the back plate 2 through a plating layer (bonding layer 4), and is brought into contact with the other end face of the green compact so as to contact the other end of the back metal 2. Plating layer on the inner surface 3 a sealing member 15b remains over the (bonding layer 4) to press fit.

  Next, the combination of these backing metal 2, 3 sealing materials 15a, 15ab and 15b and 2 green compacts in a reducing atmosphere or vacuum sintering furnace is 800-1150 ° C, preferably 850-1000. The sintering is formed at a temperature of 20 ° C. for 20 to 120 minutes, preferably 30 to 90 minutes.

In this sintering process, nickel (Ni) and phosphorus (P) in the green compact component generate Ni ₃ P in the liquid phase, but 0.1 wt.% Of the phosphorus component generating Ni ₃ P in the liquid phase. % Or more and less than 0.5% by weight, the amount of Ni ₃ P generated in the liquid phase is reduced, and does not flow out during sintering. The amount of liquid phase Ni ₃ P required to join the bonding layers 6a and 6b to the bonding layer 4 becomes lower, and as the temperature decreases during cooling (cooling) after sintering, the back metal 2, the porous metal firing Peeling due to shrinkage of the porous metal sintered layers 6a and 6b does not occur at the bonding surfaces of the bonding layers 6a and 6b and the bonding layer 4.

Further, since a joining layer 4 composed of two plating layers of a nickel plating layer and a copper plating layer is formed on the inner surface 3 of the cylindrical backing metal 2, the backing metal 2 and the porous metal firing are formed in the sintering process. Strong integration through the bonding layer 4 is performed between the binder layers 6a and 6b. At the same time, each of the sealing materials 15a, 15ab and 15b is integrally bonded to the bonding layer 4, and partly alloyed with the end faces 13, 13a, 14 and 14b of the porous metal sintered layers 6a and 6b to be integrated. Be joined. The joining strength (shear strength) between the cylindrical backing metal 2 and the porous metal sintered layers 6a and 6b joined to the inner surface 3 of the backing metal 2 via the joining layer 4 is 6.5 N / mm ² or more. Show. In this way, the inner surfaces of the porous metal sintered layers 6a and 6b sintered on the inner surface 3 of the cylindrical back metal 2 through the bonding layer 4 are cut so that the roughness thereof is 10 ⁻³ mm or less. In this case, an annular groove 32 is formed on the inner peripheral surface 30 of the sealing material 15ab before or after the machining, and at the substantially central portion in the axial direction of the back metal 2. One end opens at the inner surface 3 and the other end communicates with the radial through-hole 17 and the through-hole 17 opened at the outer surface 19, and at one end opens into the groove 32 at the substantially central portion in the axial direction of the sealing material 15 ab. At the end, a through-hole 16 in the radial direction opened on the outer peripheral surface 31 side is formed and sealing materials 15a, 15ab and 15b made of pure copper are formed on the end portion of the back metal 2 and the inner surface 3 of the back metal 2 in the annular gap 5. When bonded via the bonding layer 4 Obtaining porous metal sintered layer 6a and 6b of the end faces 13, 13a, 14 and are joined together to 14b, moreover, a desired porous hydrostatic gas radial bearing 1 having a bearing surface 18a and 18b on.

  According to this manufacturing method, the bonding strength between the inner surface 3 of the back metal 2 of the sealing materials 15a, 15ab and 15b and the end surfaces 13, 13a, 14 and 14b of the porous metal sintered layers 6a and 6b is increased, and sealing is performed. The materials 15a, 15ab and 15b do not peel from the porous metal sintered layers 6a and 6b, and the high pressure gas leaks from the end faces 13, 13a, 14 and 14b of the porous metal sintered layers 6a and 6b. It can be eliminated, the utilization efficiency of the supplied high-pressure gas can be increased, and not only a desired gas film can be formed in the bearing gap 36, but also after the cutting or grinding of the porous metal sintered layers 6a and 6b. Without the need for a sealing work step with a sealing material made of epoxy resin or phenol resin, and without waiting for drying or solidification of epoxy resin or phenol resin, etc. A temporary product can be obtained by completing the cutting or grinding of the bonding layers 6a and 6b, and the bonding layer 4 formed on the inner surface 3 of the back metal 2 and the sealing materials 15a, 15ab and 15b, and Since the porous metal sintered layers 6a and 6b are metal-to-metal bonded, the bonding force is strong, and the sealing materials 15a, 15ab and 15b are back metal 2 by the high-pressure gas supplied to the porous metal sintered layers 6a and 6b. No peeling or the like occurs from the inner surface 3 of the metal and the end surfaces 13, 13a, 14 and 14b of the porous metal sintered layers 6a and 6b, and the end surfaces 13, 13a, 14 and 14b of the porous metal sintered layers 6a and 6b. In addition to being able to maintain a reliable sealing over a long period of time, air forming a gas film in the vicinity 34a and 34b between the two porous metal sintered layers 6a and 6b can be appropriately released to the outside, 2 pieces The retention of air in the vicinity 34a and 34b between the porous metal sintered layers 6a and 6b can be avoided and heat generation of air can be suppressed. Thus, the bearing surfaces 18a and 18b side and the rotary shaft 35 side It is possible to provide the porous hydrostatic gas bearing 1 that can avoid the thermal expansion of the rotating shaft 35 and can rotate the rotating shaft 35 at higher speed with respect to the bearing surfaces 18a and 18b.

  The sealing material disposed between the porous metal sintered layers 6a and 6b is not limited to the sealing material 15ab described above, and may be a sealing material that does not have the groove 32, for example.

It is sectional drawing which shows the porous static pressure gas radial bearing of this invention. It is the II-II arrow directional cross-sectional view shown in FIG. It is a plane sectional view of one sealing material shown in FIG. It is a perspective view of one sealing material shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Porous static pressure gas radial bearing 2 Back metal 3 Inner surface 4 Joining layer 5 Annular gap 6a, 6b Porous metal sintered layer 7, 8 Annular groove 9, 10 Annular end surface 11 Hole 12 Supply means 13, 13a, 14, 14b End surface 15a, 15ab and 15b Sealing material 16, 17 Through hole 18a, 18b Bearing surface 19 Outer surface 20 Hole

Claims (11)

  Each of the cylindrical back metal made of stainless steel, at least two porous metal sintered layers juxtaposed on the cylindrical inner surface of the back metal with an annular gap in the axial direction, and each of the porous metal sintered layers In order to supply a high-pressure gas to the inner surface of the back metal, the supply means is formed with an opening on the inner surface side and has a groove in which the opening on the inner surface side is covered with a porous metal sintered layer, To seal the end surface of the porous metal sintered layer in the end portion of the back metal and the annular gap, the sealing material integrally joined to the end portion of the back metal and the end surface of the porous metal sintered layer in the annular space, and the ring A radial through-hole provided in a sealing material that seals the end face of the porous metal sintered layer in the gap, and a through-hole provided in the back metal so as to communicate with the outside of the back metal Porous static pressure gas bearing.   A bonding layer is formed on the inner surface of the back metal, and each porous metal sintered layer is integrally bonded to the inner surface of the back metal via the bonding layer, and each sealing material is bonded to the inner surface of the back metal. The porous static pressure gas bearing according to claim 1, wherein the porous static pressure gas bearing is made of pure copper.   The bonding layer includes two plating layers, a nickel plating layer and a copper plating layer. The nickel plating layer is bonded to the inner surface of the back metal, and the porous metal sintered layer and the sealing material are copper plating layers. The porous static pressure gas bearing according to claim 2, wherein   The porous static pressure gas bearing according to claim 2 or 3, wherein oxygen-free copper or tough pitch copper is used as the pure copper.   The porous metal sintered layer comprises 4 wt% or more and 10 wt% or less of tin, 10 wt% or more and 40 wt% or less of nickel, 0.1 wt% or more and less than 0.5 wt% of phosphorus, 2 wt% 5. The porous static pressure gas bearing according to claim 1, wherein the porous material is composed of inorganic particles of not less than 10% and not more than 10% by weight and the balance is copper.   The porous hydrostatic gas bearing according to claim 5, wherein the inorganic substance particles comprise at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Preparing a cylindrical backing metal made of stainless steel, and forming at least two annular grooves at predetermined intervals in the axial direction on the cylindrical inner surface of the backing metal;
Forming a bonding layer consisting of two plating layers, a nickel plating layer bonded to the inner surface of the back metal and a copper plating layer bonded to the nickel plating layer, on the inner surface of the back metal;
4% by weight to 10% by weight tin, 10% by weight to 40% by weight nickel, 0.1% by weight to less than 0.5% by weight phosphorus, and 2% by weight to 10% by weight inorganic The material particles and the balance copper are mixed to form a mixed powder, the mixed powder is loaded into a mold, and a predetermined compacting pressure is applied to form two cylindrical green compacts made of the mixed powder. Forming a step;
Preparing at least three annular sealing materials made of pure copper;
One sealing material is press-fitted onto the inner surface of one end of the back metal via a bonding layer, and then one green compact is brought into contact with the inner surface of the back metal via the bonding layer. And then contact the end face of one green compact between the two annular grooves in the axial direction and press-fit the other sealing material to the inner surface of the back metal via the joining layer, Further, the other green compact is brought into pressure contact with the inner surface of the back metal through a bonding layer in contact with the other sealing material, and the other end of the back metal is brought into contact with the end surface of the other green compact. A step of press-fitting a sealing material remaining on the inner surface via a bonding layer;
A step of sintering these in a reducing atmosphere or in vacuum at a temperature of 800 to 1150 ° C. for 20 to 120 minutes, and simultaneously bonding the green compact to the inner surface of the backing metal via the bonding layer. When,
After sintering, the step of performing cutting or grinding on the inner surface of the porous metal sintered layer obtained by sintering the green compact while integrally bonding to the inner surface of the back metal through the bonding layer;
It has
A porous hydrostatic gas bearing in which a sealing material made of pure copper is joined to an end portion of a back metal and an inner surface of the back metal in an annular gap via a joining layer and is integrally joined to an end face of the porous metal sintered layer A method for producing a porous hydrostatic gas bearing, characterized by comprising:   The manufacturing method of the porous hydrostatic gas bearing of Claim 7 which comprises the process of forming the through-hole of a radial direction in a back metal and another sealing material.   The manufacturing method of the porous hydrostatic gas bearing of Claim 7 or 8 which comprises the process of forming a cyclic | annular groove | channel in the internal peripheral surface of another sealing material.   The porous static pressure according to any one of claims 7 to 9, wherein the inorganic substance particles comprise at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Manufacturing method of gas bearing.   The method for producing a porous hydrostatic gas bearing according to any one of claims 7 to 10, wherein oxygen-free copper or tough pitch copper is used as the pure copper.

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