JP2009287120A - Bearing material for porous hydrostatic gas bearing, and porous hydrostatic gas bearing using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing material for a porous hydrostatic gas bearing which makes it possible to effect firm joining and integration without causing exfoliation or the like between the porous sintered metal layer and the supporting metal made of stainless steel, and enhance porosity of the porous sintered metal layer to increase the floating amount by the compressed gas circulating through the porous sintered metal layer, and to provide a porous hydrostatic gas bearing using the same. <P>SOLUTION: Disclosed is a bearing material including supporting metal 2 made of stainless steel, and a porous sintered metal layer 4 integrated with at least one surface of the supporting metal 2 by a bonding layer 3. Particles of an inorganic substrate are dispersed and contained at grain boundaries of the porous sintered metal layer 4. The porous sintered metal layer 4 containing the particles of the inorganic substance are composed of, by weight, 4 to 10% tin, 10 to 40% nickel, not less than 0.1 and less than 0.5% phosphorus, and the balance copper. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to a bearing material for a hydrostatic gas bearing provided with a porous sintered metal layer, and a porous hydrostatic gas bearing using the bearing material.

  Porous static pressure gas bearings have been attracting attention as having excellent high-speed stability and high load capacity, and various researches have been conducted, but there are some problems to be overcome in practical use.

  For porous static pressure gas bearings, many bearing materials are used in which a porous sintered metal body is assembled to a back metal that has been supplied with compressed gas. As a material for forming a porous sintered metal body in this bearing material, Of these, those mainly composed of bronze, aluminum alloy and stainless steel, particularly those mainly composed of bronze are used.

By the way, the bearing material used for the porous hydrostatic gas bearing is required to have sufficient air permeability and surface roughness of the order of 10 ⁻³ mm. Although the sintered metal body itself has a preferable air permeability, since the dimensional accuracy and surface roughness of the porous sintered metal body are not sufficient, in many cases, the surface is machined.

  This machining is mainly performed by lathe, milling and grinding, but this lathe, milling and grinding causes clogging on the surface of the porous sintered metal body, which greatly affects its air permeability (drawing characteristics). Will give. In particular, in grinding, plastic flow is induced on the surface of the porous sintered metal body to cause burrs and burrs.

  Further, as described above, the porous sintered metal body is assembled to the back metal to which the compressed gas supply means has been applied. For example, in the case of a porous static pressure radial gas bearing, the cylindrical back metal is used for this assembly. A means for press-fitting a cylindrical porous sintered metal body is employed.

  In the case of a plain bearing, even if such a press-fitting means is used, there is no problem. However, in a porous hydrostatic gas bearing, there is a minute amount in the contact portion between the two seemingly press-fitted. Due to the presence of the gap, the gas leakage from the gap may be larger than the original flow of the compressed gas in the porous sintered metal body. Naturally, the leakage of the gas from the gap results in a decrease in performance such as a decrease in load capacity as a porous hydrostatic gas bearing. Therefore, it is preferable to prevent this as much as possible.

  In order to cope with this, if the interference is increased and fitting is performed with a large pressure input, the gap in this part can be almost completely eliminated. There is a risk that the plastic flow of the sintered metal may occur on the outer surface side of the metal body, and therefore, the problem that the flow of the compressed gas is greatly hindered on the fitting surface side of the porous sintered metal body after fitting on the back metal. Occurs.

JP-A-11-158511

  In view of the above problems, the present applicant has proposed a technique (hereinafter referred to as “prior art”) described in Japanese Patent Application No. 9-342242 (Japanese Patent Laid-Open No. 11-158511), and has solved the above problem. That is, the prior art includes a backing metal and a porous sintered metal layer bonded to at least one surface of the backing metal, and inorganic substance particles are contained in the grain boundaries of the porous sintered metal layer. The present invention relates to a bearing material for a porous static pressure gas bearing. And in the prior art, in addition to inorganic substance particles, as specific examples, by weight, tin 4-10%, nickel 10-40%, phosphorus 0.5-4%, graphite 3-10% and the balance copper A porous sintered metal layer is disclosed.

  In the bearing material disclosed in this prior art, (1) since the grain boundary of the porous sintered metal layer contains inorganic substance particles such as graphite, the surface is clogged even if machined. (2) Since the porous sintered metal layer is bonded and integrated with the back metal, there is no leakage of compressed gas from the bonded portion, and the sintered layer is formed by supplying air pressure. There is an effect that the deformation of can be extremely reduced.

In the porous sintered metal layer of the bearing material disclosed in this prior art, nickel (Ni) and phosphorus (P) in the components generate liquid phase Ni ₃ P in the sintering process, and the sintering temperature is increased. At the same time, the sintered layer is alloyed by mutual diffusion between the solid phase and the liquid phase, which becomes increasingly active, and the porous phase is sintered with good wettability of the liquid phase Ni ₃ P on the back metal (steel material). The bonded metal layer and the back metal are joined and integrated.

However, when stainless steel having excellent corrosion resistance, particularly rust resistance, is used as the backing metal, several problems have been raised in joining and integrating the backing metal and the porous sintered metal layer. (1) When a porous sintered metal layer is bonded to at least one surface of a stainless steel back metal during sintering, the surface of the back metal, in other words, the connection between the back metal and the porous sintered metal layer Chromium oxide such as chromium oxide (Cr ₂ O ₃ ) is generated at the interface, and the integration of the porous sintered metal layer to the back metal surface is hindered by the presence of chromium oxide at the bonding interface, (2) When a large amount of Ni ₃ P in the liquid phase is generated during sintering, such Ni ₃ P in the liquid phase flows out during the sintering and is necessary for joining the porous sintered metal layer to the surface of the back metal. The amount of liquid phase of Ni ₃ P is reduced, the bonding force between the porous sintered metal layer and the back metal is weakened, and the porous sintered metal layer is accompanied by a decrease in temperature during cooling (cooling) after sintering. Due to shrinkage of the porous sintered metal layer at the bonding surface between the metal and the back metal And so on. In particular, the above problem (2) causes a defect such as leakage of compressed gas from the joint surface in the porous hydrostatic gas bearing.

As a result of intensive studies in view of the above problems, the present inventor has applied a plating layer to the surface of the back metal made of stainless steel, and the bonding layer made of such a plating layer is used as the back metal. And the porous sintered metal layer are interposed between the back metal and the porous sintered metal layer to prevent the formation of chromium oxide at the joining interface between the stainless steel and the back metal surface. And found that the porous sintered metal layer can be joined and integrated, and with respect to the problem (2), cooling after sintering can be achieved by reducing the amount of Ni ₃ P generated in the liquid phase. The amount of shrinkage of the porous sintered metal layer at the time is reduced, and the porous sintered metal layer can be integrated and bonded without causing separation at the bonding surface between the porous sintered metal layer and the back metal. Circulate the porous sintered metal layer Found that increasing the flying height due to condensation gas.

  The present invention has been made on the basis of the above-mentioned knowledge, and the object of the present invention is to perform strong joint integration without causing separation between the porous sintered metal layer and the back metal made of stainless steel. And a bearing material for a porous hydrostatic gas bearing capable of increasing the porosity of the porous sintered metal layer and increasing the flying height of the compressed gas flowing through the porous sintered metal layer. Another object of the present invention is to provide a porous hydrostatic gas bearing.

  Further, in such a bearing material for a porous hydrostatic gas bearing, a supply means for supplying a compressed gas to the porous sintered metal layer is provided on the back metal. It is preferable that the sprayed metal layer is uniformly and uniformly ejected from the surface of the bonded metal layer, and in particular, it is a back metal used for a bearing material for a porous hydrostatic gas radial bearing and has a cylindrical inner surface. In the case of providing a compressed gas supply means, it is required that it can be easily formed and has excellent manufacturability.

  Another object of the present invention is to provide a porous hydrostatic gas radial bearing that is capable of minimizing the deviation of the jet of compressed gas from the surface of the porous sintered metal layer and is excellent in manufacturability. An object of the present invention is to provide a bearing material and a porous static pressure gas radial bearing using the same.

  A bearing material for a porous hydrostatic gas bearing according to the first aspect of the present invention includes a back metal made of stainless steel, and a porous sintered metal layer integrated with at least one surface of the back metal through a bonding layer. The inorganic sintered particles are dispersed and contained in the grain boundaries of the porous sintered metal layer. Here, the porous sintered metal layer containing the inorganic particles is 4% by weight or more and 10% by weight. % Of tin, 10% to 40% nickel, 0.1% to less than 0.5% phosphorus, and the balance being copper.

According to the bearing material for the porous hydrostatic gas bearing of the first aspect, the content of the phosphorus component that generates liquid phase Ni ₃ P in the sintering process is 0.1 wt% or more and less than 0.5 wt% Therefore, the amount of generation of liquid phase Ni ₃ P is reduced, the amount of liquid phase Ni ₃ P does not flow out during sintering, and the amount necessary for bonding the porous sintered metal layer to the bonding layer It becomes liquid phase Ni ₃ P, and the bonding force between the porous sintered metal layer and the back metal through the bonding layer is enhanced. Moreover, since the amount of generated liquid phase Ni ₃ P is small, cooling after sintering ( Since the amount of shrinkage of the porous sintered metal layer during cooling) is small, the porosity is reduced at each joining surface through the joining layer of the back metal and the porous sintered metal layer due to the shrinkage of the porous sintered metal layer. No peeling of the sintered metal layer occurs.

In addition, since the amount of liquid phase Ni ₃ P produced is small and the bonding layer is interposed, the porosity of the porous sintered metal layer integrated with the back metal is increased. The pressure loss of the compressed gas flowing through the layer is reduced, and the air supply pressure ejected to the surface (bearing surface) of the porous sintered metal layer is relatively increased, whereby the flying height can be increased. Accordingly, the porous sintered metal layer and the back metal are firmly integrated through the bonding layer, and the porous static pressure can increase the floating amount due to the increased porosity of the porous sintered metal layer. It can be a bearing material for a gas bearing.

  In the bearing material for the porous hydrostatic gas bearing of the second aspect of the present invention, in the bearing material of the first aspect, the inorganic substance particles are contained in the porous sintered metal layer in a proportion of 2 wt% or more and 10 wt% or less. The inorganic particles are contained in at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide and silicon carbide, as in the bearing material of the third aspect of the present invention. Consist of one.

  The inorganic substance particles dispersed and contained in the grain boundaries of the porous sintered metal layer are not themselves plastically deformed by machining, and in addition, plastic deformation of the metal part of the base of the porous sintered metal layer is prevented. The clogging of the porous sintered metal layer in machining can be suppressed by the action of dividing and reducing.

  Even if the backing metal is formed in a cylindrical shape like the bearing material for the porous static pressure gas bearing of the fourth aspect of the present invention, it is replaced with the porous static pressure of the fifth aspect of the present invention. Like a bearing material for a pressurized gas bearing, it may be formed in a flat plate shape. In the former case, the porous sintered metal layer containing inorganic substance particles is formed on one cylindrical surface of the back metal. In the latter case, the porous sintered metal layer containing inorganic particles is integrated on one surface of the flat plate of the back metal via the bonding layer. .

  The bonding layer includes at least a nickel plating layer as in the bearing material for the porous hydrostatic gas bearing of the sixth aspect of the present invention, and the porous hydrostatic gas of the seventh aspect of the present invention. Like a bearing material for a bearing, it may include two plating layers, a nickel plating layer and a copper plating layer. In any case, the nickel plating layer is bonded to at least one surface of the back metal. In the case where the bonding layer includes two plating layers of a nickel plating layer and a copper plating layer, the porous sintered metal layer may be bonded to the copper plating layer. Each of the nickel plating layer and the copper plating layer is formed by electroplating.

  As in the bearing material of the sixth aspect of the present invention, a joining layer including a nickel plating layer is formed on the surface of a back metal made of stainless steel, and the nickel plating layer is joined to at least one surface of the back metal. In this case, strong joint integration is performed between the two. Further, like the bearing material of the seventh aspect of the present invention, the bonding layer formed on the surface of the back metal includes two plating layers of a nickel plating layer and a copper plating layer, and the nickel plating layer is made of the back metal. Even if the porous sintered metal layer is bonded to at least one surface and bonded to the copper plating layer, strong bonding and integration are similarly performed between the two. Therefore, in any case, peeling or the like does not occur in the joining portion in the back metal made of stainless steel, the porous sintered metal layer, and the joining layer. Further, when the copper plating layer in the bearing material of the seventh aspect is formed on the surface of the nickel plating layer as in the bearing material of the eighth aspect of the present invention, the two-layer plating layer is firmly joined and integrated. In addition, it is possible to secure strong integration between the back metal and the porous sintered metal layer as described above.

  The copper plating layer preferably has a thickness of 10 μm or more and 25 μm or less, like the bearing material of the ninth aspect of the present invention, and more preferably like the bearing material of the tenth aspect of the present invention, It has a thickness of 10 μm or more and 20 μm or less, and the nickel plating layer preferably has a thickness of 2 μm or more and 20 μm or less like the bearing material of the eleventh aspect of the present invention. Like the bearing material of the twelfth aspect of the invention, it has a thickness of 3 μm or more and 15 μm or less.

  The porous static pressure gas bearing of the present invention uses a bearing material for a porous static pressure gas bearing according to any one of the first to twelfth aspects, and is provided on a back metal and is inorganic. Means is provided for supplying a compressed gas to the porous sintered metal layer containing the dispersed material particles.

  According to the porous static pressure gas bearing of the present invention, it can be applied as a porous static pressure gas radial bearing by using the bearing material as in the fourth aspect, or use the bearing material as in the fifth aspect. Therefore, it can be applied as a porous static pressure gas thrust bearing.

  The bearing material for the porous hydrostatic gas radial bearing according to the first aspect of the present invention is made of stainless steel and has a cylindrical inner surface, and the inner surface of the back metal is opened on the inner surface side in the axial direction. And a plurality of annular grooves provided in the axial direction from one annular end surface to the other annular end surface of the back metal so as to communicate with each other. Cylindrical porous sintering that covers the dead end hole for mutual communication provided on the inner surface of the back metal and the opening of each annular groove on the inner surface side of the back metal and is integrated with the cylindrical inner surface of the back metal via a bonding layer And a metal layer.

  According to the bearing material for the porous hydrostatic gas radial bearing of the first aspect, the interior of the back metal is such that a dead end hole for interconnecting a plurality of annular grooves is not opened on the inner surface side of the back metal. Therefore, it is possible to avoid the supply of compressed gas from the dead end hole directly to the porous sintered metal layer via the inner surface of the back metal, and the compression supplied to the dead end hole for mutual communication can be avoided. As a result of supplying the gas to the porous sintered metal layer through each of the annular grooves, the compressed gas can be ejected from the surface of the porous sintered metal layer substantially evenly, and the dead holes for mutual communication are provided on the back metal. Since it is provided inside, such a dead end hole can be easily formed from one annular end face of the back metal using a drill or the like, so it is compared with the formation of a groove for mutual communication on the cylindrical inner face. Therefore, it becomes extremely excellent in manufacturability.

  Both ends of the dead end holes for mutual communication may be opened by corresponding annular end faces, but preferably, like the bearing material for the porous hydrostatic gas radial bearing of the second aspect of the present invention. One end of the dead end hole for mutual communication is opened at the annular end face of the back metal, and the other end of the dead end hole for mutual communication is closed by the back metal itself before the other annular end face of the back metal. In this case, the bearing material for the porous static pressure gas radial bearing is used for fitting a plug that closes one end of a dead end hole for communication as in the third aspect of the present invention. The fitting means may be further provided, and the fitting means may be provided with a thread groove like the bearing material for the porous hydrostatic gas radial bearing of the fourth aspect of the present invention. Even when both ends of the dead end holes for mutual communication are opened, the bearing material of the present invention includes a fitting means including a screw groove for fitting a plug that closes both ends. Good.

  In the present invention, a dead end hole for mutual communication may be used as a dead end hole for compressed gas supply, but the bearing material for the porous hydrostatic gas radial bearing of the present invention is preferably Like that of the fifth aspect, it is open for the outer surface of the back metal and extends in the radial direction from the outer surface of the back metal toward the dead end hole for mutual communication. A dead end hole is further provided.

  Similar to the bearing material for the porous hydrostatic gas bearing, in the bearing material for the porous hydrostatic gas radial bearing of the present invention, as in the sixth aspect, the porous sintered metal layer is made of tin. A grain boundary of sintered metal containing nickel, phosphorus and copper, and inorganic substance particles dispersed in the grain boundary of sintered metal. In this case, the porous static pressure of the seventh aspect Like the bearing material for gas radial bearings, the grain boundaries of the sintered metal are 4 wt% to 10 wt% tin, 10 wt% to 40 wt% nickel, 0.1 wt% to 0 wt%. Less than 5 wt% phosphorus and the balance contains copper, and the inorganic material particles are contained in an amount of 2 wt% or more and 10 wt% as in the bearing material for the porous hydrostatic gas radial bearing of the eighth aspect. Of the bearing material for the porous hydrostatic gas radial bearing of the ninth aspect. Sea urchin, inorganic material particles, graphite, boron nitride, fluorinated graphite, calcium fluoride, aluminum oxide, may consist of at least one of silicon oxide and silicon carbide. Similarly to the bearing material for the porous static pressure gas bearing, the joining layer may include at least a nickel plating layer as in the bearing material for the tenth porous static pressure gas radial bearing of the present invention. In this case, the nickel plating layer is bonded to the cylindrical inner surface of the back metal. The joining layer is also composed of two layers of a nickel plating layer and a copper plating layer formed on the surface of the nickel plating layer, like the bearing material for the porous hydrostatic gas radial bearing of the eleventh aspect of the present invention. In this case, the nickel plating layer is preferably bonded to the cylindrical inner surface of the back metal, and the porous sintered metal layer is preferably bonded to the copper plating layer.

  In the bearing material for the porous hydrostatic gas radial bearing of the present invention, the copper plating layer preferably has a thickness of 10 μm or more and 25 μm or less, more preferably, like that of the twelfth aspect, more preferably Has a thickness of 10 μm or more and 20 μm or less like that of its thirteenth aspect, and the nickel plating layer is preferably 2 μm or more and 20 μm or less like that of its thirteenth aspect More preferably, like the fourteenth aspect, it has a thickness of 3 μm or more and 15 μm or less.

  According to each of the bearing materials for the porous static pressure gas radial bearings of the sixth aspect to the fourteenth aspect, it is possible to obtain the same effect as that of the above-described bearing material for the porous static pressure gas bearing. it can.

  According to the present invention, since the porous sintered metal layer has a small amount of shrinkage after sintering, the porous sintered metal layer can be firmly integrated with the backing metal made of stainless steel through the bonding layer. Further, since the porosity of the porous sintered metal layer is increased, the pressure loss of the compressed gas flowing through the porous sintered metal layer is reduced, and as a result, the surface (bearing surface) of the porous sintered metal layer The air supply pressure ejected to the air increases relatively, and the flying height can be increased.

  Further, according to the present invention, the biasing material for the porous hydrostatic gas radial bearing which can reduce the deviation of the jet of the compressed gas from the surface of the porous sintered metal layer as much as possible and has excellent manufacturability. And a porous hydrostatic gas radial bearing using the same can be provided.

FIG. 1 is a sectional view showing a porous hydrostatic gas radial bearing of the present invention. 2 is a cross-sectional view taken along line II-II shown in FIG. FIG. 3 is a plan view showing a porous hydrostatic gas thrust bearing of the present invention. 4 is a cross-sectional view taken along line IV-IV shown in FIG. FIG. 5 is a graph showing the relationship between the thickness of the bonding layer and the shear strength of the porous hydrostatic gas bearing of the present invention. FIG. 6 is a graph showing the porosity of the porous sintered metal layer. FIG. 7 is a graph showing the open flow rate and the flow rate ratio of the porous static pressure gas radial bearing and the bearing material. FIG. 8 is a graph showing the relationship between the load load (kgf) and the flying height (μm) in a porous static pressure gas radial bearing. FIG. 9 shows another example of the porous hydrostatic gas radial bearing of the present invention, and is a cross-sectional view taken along the line IX-IX of FIG. 10 is a cross-sectional view taken along line XX shown in FIG. 11 shows the radial bearing material of the example of FIG. 9, and is a cross-sectional view taken along the line XI-XI of FIG. 12 is a cross-sectional view taken along line XII-XII shown in FIG. 13 shows still another example of the porous hydrostatic gas radial bearing of the present invention, and is a cross-sectional view taken along line XIII-XIII in FIG. 14 is a left side view of the example shown in FIG.

  Hereinafter, the present invention and embodiments of the present invention will be described based on preferred examples with reference to the drawings. Note that the present invention is not limited to these examples.

  In the porous static pressure gas bearing, the porous static pressure gas radial bearing 1 of this example shown in FIGS. 1 and 2 includes a back metal 2 made of stainless steel and formed in a cylindrical shape, and one cylindrical shape of the back metal 2. A porous sintered metal layer 4 integrated with the inner surface 9 via the bonding layer 3, a compressed gas supply hole 5 provided in the back metal 2, and an inner surface 9 of the back metal 2 aligned in the axial direction. A plurality of annular grooves which are formed to be open on the inner surface 9 side and which are covered with the porous sintered metal layer 4 and covered with the porous sintered metal layer 4. 6 and an inner surface 9 of the back metal 2 that is open on the inner surface 9 side and extends in the axial direction so that the annular grooves 6 communicate with each other. A cylindrical inner surface of the binder metal layer 4 is used as a bearing surface 8, and a hole 5, an annular groove 6 and a groove provided in the back metal 2. Supply means is configured to supply compressed gas to the porous sintered metal layer 4 by.

  In the porous static pressure gas bearing, the porous static pressure gas thrust bearing 11 of this example shown in FIGS. 3 and 4 includes a back plate 2 made of stainless steel and formed into a flat plate shape, and one of the flat plate shapes of the back plate 2. Formed on one flat surface of the back metal 2, the porous sintered metal layer 4 integrated on the flat surface which is a surface through the bonding layer 3, the compressed gas supply hole 5 provided in the back metal 2, and the back metal 2. A plurality of annular grooves 6 and a groove 7 formed on one flat surface of the back metal 2 and interconnecting the annular grooves 6, and the flat outer surface of the porous sintered metal layer 4. Is a bearing surface 8, and a supply means for supplying compressed gas to the porous sintered metal layer 4 is constituted by the hole 5, the annular groove 6 and the groove 7 provided in the back metal 2.

  In the porous hydrostatic gas radial bearing 1 and the porous hydrostatic gas thrust bearing 11, austenitic stainless steel, martensitic stainless steel, or ferritic stainless steel is used as the stainless steel forming the back metal 2. In particular, martensitic stainless steel or ferritic stainless steel having a low chromium (Cr) content is preferable.

  The bonding layer 3 includes a nickel plating layer bonded to one surface of the back metal 2 and a copper plating layer bonded to the surface of the nickel plating layer and the porous sintered metal layer 4 bonded to the surface. Includes two plating layers. Depending on the degree of pressurization during the formation of the porous sintered metal layer 4, in order not to cause peeling or the like at each joint between the backing metal 2 and the porous sintered metal layer 4 via the bonding layer 3, The nickel plating layer has a thickness of 2 μm to 20 μm, preferably 3 μm to 15 μm, and the copper plating layer has a thickness of 10 μm to 25 μm, preferably 10 μm to 20 μm.

The porous sintered metal layer 4 includes 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, The inorganic substance is contained in an amount of 10% by weight or more and 10% by weight or less and the balance is made of copper. The phosphorus component in the component produces liquid phase Ni ₃ P in the sintering process, promotes the sintering and promotes the diffusion of the nickel component into the bonding layer 3 formed on one surface of the back metal 2, It plays a role of firmly integrating the porous sintered metal layer 4.

Further, by making the blending amount of the phosphorus component 0.1% by weight or more and less than 0.5% by weight, the amount of shrinkage at the time of cooling after sintering of the porous sintered metal layer 4 can be kept low. No peeling or the like of the porous sintered metal layer 4 from one surface of the back metal 2 due to the shrinkage of the sintered metal layer 4 occurs. Furthermore, the porosity of the porous sintered metal layer 4 is increased and the porous sintered metal layer 4 is circulated by reducing the amount of phosphorous component and reducing the amount of liquid phase Ni ₃ P produced. By reducing the pressure loss of the compressed gas, the air supply pressure ejected to the bearing surface 8 of the porous sintered metal layer 4 is relatively increased, and the flying height can be increased.

  The inorganic substance particles dispersedly contained in the porous sintered metal layer 4 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 an inorganic substance is dispersed and contained in the substrate (grain boundary) made of tin, nickel, phosphorus and copper of the porous sintered metal layer 4, the material itself is not plastically deformed by machining. In addition, clogging of the porous sintered metal layer in machining can be suppressed because the plastic deformation of the metal portion of the base of the porous sintered metal layer 4 is divided and reduced. And, the blending amount of these inorganic substance particles is suitably a ratio of 2% by weight or more and 10% by weight or less. When the blending amount is less than 2% by weight, the function of dividing and reducing the plastic deformation of the metal portion of the base of the porous sintered metal layer 4 is not sufficiently exerted, and when the blending amount exceeds 10% by weight, it becomes porous. The sinterability of the sintered metal layer 4 is hindered.

  Next, a bearing material for a porous hydrostatic gas bearing and a method for manufacturing a porous hydrostatic gas bearing using the bearing material will be described.

[Method for Manufacturing Porous Static Pressure Gas Thrust Bearing 11]
A disc-shaped backing metal 2 made of austenitic stainless steel, martensitic stainless steel or ferritic stainless steel is prepared, and a plurality of concentric annular grooves 6 and the annular grooves 6 are formed on one surface of the backing metal 2. Grooves 7 that communicate with each other are formed, and compressed gas supply holes 5 that open to the grooves 7 from the other surface of the back metal 2 are formed.

  A nickel plating layer having a thickness of 2 to 20 μm, preferably 3 to 15 μm, is formed on a flat surface, which is one surface excluding these grooves 6, 7 and holes 5, of the back metal 2 on which the annular grooves 6, the grooves 7 and the holes 5 are formed. Then, 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 nickel plating is applied to one flat surface excluding the grooves 6 and 7 and the holes 5 of the back metal 2. A two-layer plating layer comprising a layer and a copper plating layer is formed. The two plating layers serve as a bonding layer 3 between the back metal 2 and the porous sintered metal layer 4.

  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 material particles 3 wt% or more and 10 wt% or less passing through 150 mesh sieve, and passing 150 mesh sieve The remainder of the electrolytic copper powder is mixed with a mixer to produce a mixed powder.

  1-15% by weight of a powder binder selected from hydroxypropylcellulose (HPC), polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), methylcellulose (MC), gelatin, gum arabic and starch An aqueous solution is added in an amount of 0.1 to 5.0% by weight with respect to the mixed powder and uniformly mixed to obtain a raw material powder having wettability. Here, the addition amount of the powder binder aqueous solution is preferably 0.1 to 5.0% by weight with respect to the metal mixed powder. In particular, if it exceeds 5.0% by weight, pores (pores) that cannot be controlled increase in the sintered body structure, which causes the strength of the porous sintered metal layer 4 to decrease. Moreover, as a solvent of a powder binder, 5-20 weight% aqueous solution of hydrophilic compounds, such as ethyl alcohol, can be used besides water.

  The raw material powder having wettability is supplied to a rolling roll by a conveyor and a hopper. For rolling raw material powder, a normal horizontal rolling mill having twin rolls can be used. A green compact sheet having a thickness of approximately 2 to 2.5 mm is produced using this horizontal rolling mill.

This green compact sheet is superposed on a back metal 2 having a plating layer on one surface except for the annular groove 6, groove 7 and hole 5, and this is placed in a reducing atmosphere or vacuum at 800 to 1150 ° C., preferably 850. Sintering is performed at a temperature of ˜1000 ° C. under a pressure of 0.1 to 5.0 kgf / cm ² , preferably 0.5 to 3.0 kgf / cm ² for 20 to 120 minutes, preferably 30 to 90 minutes.

In this sintering process, although nickel in component (Ni) and phosphorus (P) generates a Ni ₃ P in the liquid phase, the phosphorus component generated the Ni ₃ P liquid phases 0.1% by weight or more 0. Since the content is less than 5% by weight, the amount of generated Ni ₃ P in the liquid phase is reduced and does not flow out during sintering, and is necessary for joining the porous sintered metal layer 4 to the joining layer 3. As the amount of liquid phase Ni ₃ P becomes lower and the temperature at the time of cooling after cooling (cooling) decreases, the porous surface of the backing metal 2, the porous sintered metal layer 4, and the bonding layer 3 is porous. Peeling does not occur at the joint surface due to the shrinkage of the sintered metal layer 4.

In addition, since a joining layer 3 composed of two plating layers, a nickel plating layer and a copper plating layer, is formed on one surface of the back metal 2, the porous sintered metal layer 4 and the back metal are used in the sintering process. 2 is firmly integrated via the bonding layer 3. Furthermore, the porosity of the porous sintered metal layer 4 is increased by reducing the amount of Ni ₃ P produced in the liquid phase, and the pressure loss of the compressed gas flowing through the porous sintered metal layer 4 is reduced. As a result, the air supply pressure ejected to the bearing surface 8 of the porous sintered metal layer 4 is relatively increased, and the flying height can be increased. Accordingly, a bearing material for the porous hydrostatic gas thrust bearing 11 in which the porous sintered metal layer 4 and the back metal 2 are firmly integrated via the bonding layer 3 can be obtained.

FIG. 5 shows a green compact sheet composed of the above components on the surface (1) a nickel plating layer having a thickness of 3 μm and a copper plating layer having a thickness of 10 μm, and (2) a nickel plating layer having a thickness of 3 μm and a thickness of 15 μm. (3) Overlaid on a back metal 2 on which three types of bonding layers 3 of a nickel plating layer having a thickness of 3 μm and a copper plating layer having a thickness of 20 μm are formed, and this is superposed in a reducing atmosphere at 930 ° C. About the bearing material obtained by sintering for 85 minutes at a temperature of 1.0 kgf / cm ² , the bonding strength between the back metal 2 and the porous sintered metal layer 4 (shear strength: N / mm ^2). ).

As can be seen from FIG. 5, in the plated layer of (1), the bonding strength (shear strength) between the back metal 2 and the porous sintered metal layer 4 is 6.5 to 7.2 N / mm ² , In the plated layer of (2), the bonding strength (shear strength) between the back metal 2 and the porous sintered metal layer 4 is 7.1 to 7.7 N / mm ^2, and in the plated layer of (3) Indicates a bond strength (shear strength) between the back metal 2 and the porous sintered metal layer 4 of 6.8 to 7.4 N / mm ² . Thus, in the plating layers (1) to (3), the bonding strength between the back metal 2 and the porous sintered metal layer 4 is 6.5 N / mm ² or more, and the final porosity Even if the flat surface of the sintered metal layer 4 is subjected to machining such as grinding or lapping, no peeling or the like occurs between the back metal 2 and the porous sintered metal layer 4.

In this way, a thrust bearing material having the porous sintered metal layer 4 sintered on the one surface of the disc-shaped back metal 2 via the bonding layer 3 is obtained. The desired porous material having the bearing surface 8 is obtained by machining the flat surface of the porous sintered metal layer 4 of the obtained bearing material by grinding or lapping so that the roughness is 10 ⁻³ mm or less. A static pressure gas thrust bearing 11 is obtained.

[Method for Manufacturing Porous Hydrostatic Gas Radial Bearing 1]
A cylindrical back metal 2 made of austenitic stainless steel, martensitic stainless steel or ferritic stainless steel is prepared, and a plurality of annular grooves 6 are formed on the inner surface 9 of the back metal 2 at equal intervals along the axial direction thereof. The annular groove 6 is formed with an axial groove 7 that communicates with each other, and a compressed gas supply hole 5 that opens from the outer surface 25 of the back metal 2 to the groove 7 is formed.

  A nickel plating layer having a thickness of 2 to 20 μm, preferably 3 to 15 μm, is formed on the inner surface 9 excluding the grooves 6, 7 and the holes 5 of the back metal 2 on which the annular grooves 6, the grooves 7 and the holes 5 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 nickel plating layer and the copper plating layer are formed on the inner surface 9 excluding the grooves 6 and 7 and the holes 5 of the back metal 2. A two-layered plating layer is formed. The two plating layers serve as a bonding layer 3 between the back metal 2 and the porous sintered metal layer 4.

  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 powder remainder is mixed with a mixer to prepare a mixed powder.

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 a cylindrical green compact.

  An annular groove 6, a groove 7 and a hole 5 are formed on the inner surface 9 of this cylindrical green compact, and a nickel plating layer and a copper plating layer are formed on the inner surface 9 excluding these grooves 6, 7 and the hole 5. It press-fits into the inner surface 9 of the cylindrical back metal 2 on which the plated layer of the layer is formed. A metal core is inserted into the inner surface of the green compact of the cylindrical backing metal 2 in which a cylindrical green compact is press-fitted into the inner surface 9, and the inner surface of the green compact and the outer surface of the metal core Fill the gap with ceramic powder.

The ceramic powder does not melt within the sintering temperature range, and any ceramic powder may be used as long as it does not react in the neutral or reducing atmosphere with respect to the components of the green compact. Examples thereof include graphite, carbon, alumina (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), zirconium oxide (ZrO ₂ ), magnesium oxide (MgO), and composite oxides thereof. If these ceramic powders are too fine, they will be difficult to handle and inferior in filling properties, and those in the range of 35 to 200 mesh are preferred.

As the metal core, a material having a large thermal expansion coefficient and durability, for example, austenitic stainless steel (thermal expansion coefficient of about 1.5 × 10 ⁻⁵ / ° C.) is exemplified as a suitable one. The core can take the form of a round bar or a hollow. The outer diameter of the metal core is preferably smaller by about 10 to 30 mm than the inner diameter of the green compact.

  Subsequently, sintering is performed at a temperature of 800 to 1150 ° C., preferably 850 to 1000 ° C. for 20 to 120 minutes, preferably 30 to 90 minutes in a reducing atmosphere or vacuum. In this sintering process, the ceramic powder restrains the amount of expansion toward the inner diameter side during sintering of the green compact and the amount of contraction toward the inner diameter side during cooling after sintering, and further sintering the core. By utilizing the expansion of time, a high contact pressure of the green compact to the bonding layer 3 is generated.

In this sintering process, although nickel in component (Ni) and phosphorus (P) generates a Ni ₃ P in the liquid phase, the phosphorus component generated the Ni ₃ P liquid phases 0.1% by weight or more 0. Since the content is less than 5% by weight, the amount of generated Ni ₃ P in the liquid phase is reduced and does not flow out during sintering, and is necessary for joining the porous sintered metal layer 4 to the joining layer 3. As the amount of liquid phase Ni ₃ P becomes lower and the temperature at the time of cooling after cooling (cooling) decreases, the porous surface of the backing metal 2, the porous sintered metal layer 4, and the bonding layer 3 is porous. No peeling due to shrinkage of the sintered metal layer 4 occurs.

In addition, since a joining layer 3 composed of two plating layers, a nickel plating layer and a copper plating layer, is formed on the cylindrical inner surface 9 of the back metal 2, the back metal 2 and the porous sintered body are sintered in the sintering process. Strong integration is performed between the metal layer 4 and the metal layer 4 via the bonding layer 3. Furthermore, the porosity of the porous sintered metal layer 4 is increased and the porous sintered metal layer 4 is circulated by reducing the amount of phosphorous component and reducing the amount of liquid phase Ni ₃ P produced. By reducing the pressure loss of the compressed gas, the pressure of air supplied to the bearing surface 8 of the porous sintered metal layer 4 is relatively increased, and the flying height can be increased. Therefore, it can be set as the bearing material for the porous static pressure gas radial bearing 1 in which the porous sintered metal layer 4 and the back metal 2 are firmly integrated via the bonding layer 3.

In this way, a radial bearing material including the porous sintered metal layer 4 sintered on the inner surface 9 of the cylindrical back metal 2 via the bonding layer 3 is obtained. In this radial bearing material, the joining strength (shear strength) between the cylindrical backing metal 2 and the porous sintered metal layer 4 sintered on the inner surface 9 of the backing metal 2 via the joining layer 3 is 6.5 N. / Mm ² or more, even if the cylindrical inner surface of the final porous sintered metal layer 4 is subjected to machining such as grinding or lapping, peeling between the back metal 2 and the porous sintered metal layer 4 Will not occur. The cylindrical inner surface of the porous sintered metal layer 4 of the obtained bearing material is machined by grinding or lapping so that the roughness is 10 ⁻³ mm or less, and a desired bearing surface 8 is provided. A porous static pressure gas radial bearing 1 is obtained.

  Examples of the present invention will be described in detail below. In the following examples and comparative examples, since the porous sintered metal layer 4 of the comparative example cannot be bonded to the back metal 2 made of stainless steel, carbon steel for machine structure (S45C) is used for the back metal 2 in the comparative example. did.

Example 1
A cylindrical backing metal 2 made of martensitic stainless steel [SUS420J2 (B)] having an inner diameter of 30 mm, an outer diameter of 45 mm, and a length of 30 mm is prepared, and the axial direction of the backing metal 2 is formed on the inner surface 9 of the cylindrical backing metal 2. Are formed with three annular grooves 6 having a width of 2 mm and a depth of 2 mm at equal intervals, and one groove 7 along the axial direction of the back metal 2 that communicates with the annular grooves 6, respectively. One hole 5 opened from the outer surface 25 of the backing metal 2 to the groove 7 was formed.

  A nickel plating layer having a thickness of 3 μm is formed on the inner surface 9 excluding these grooves 6, 7 and holes 5 of the cylindrical back metal 2 in which the annular grooves 6, the grooves 7 and the holes 5 are formed, and a thickness of 10 μm is formed on the surface of the nickel plating layer. A two-layer plating layer was formed with the copper plating layer.

  8% by weight of atomized tin powder passing through a 250 mesh screen, 28% by weight of electrolytic nickel powder passing through a 250 mesh screen, and 1.0% of copper phosphorous (phosphorus 14.5%) powder passing through a 120 mesh screen 5% by weight of graphite powder (inorganic substance particles) passing through a 150 mesh sieve and the remainder of the electrolytic copper powder passing through a 150 mesh sieve are mixed for 5 minutes with a V-type mixer to obtain a mixed powder (copper: 58.85 wt%, tin: 8 wt%, nickel: 28 wt%, phosphorus: 0.15 wt%, graphite: 5 wt%).

This mixed powder was loaded into a mold, and a cylindrical green compact having an inner diameter of 26 mm, an outer diameter of 30 mm, and a length of 30 mm at a molding pressure of 3 ton / cm ² was produced.

A cylindrical green compact was press-fitted into the inner surface 9 of the cylindrical back metal 2. A round bar (core) made of austenitic stainless steel having an outer diameter of 16 mm and a length of 30 mm is inserted into the inner surface of the green compact press-fitted to the inner surface 9 of the back metal 2 and the cylindrical green compact is formed. After filling the gap between the inner surface and the outer surface of the round bar with ceramic powder (a mixture of Al ₂ O ₃ : 83 wt% and SiO ₂ : 17 wt%, 35 to 150 mesh), it is 930 ° C. in an ammonia decomposition gas atmosphere. The bearing material for the porous hydrostatic gas radial bearing 1 in which the porous sintered metal layer 4 is integrally bonded to the inner surface 9 of the cylindrical back metal 2 via the bonding layer 3 is obtained. It was. The joining strength (shear strength) between the backing metal 2 and the porous sintered metal layer 4 integrally joined to the inner surface 9 of the backing metal 2 in this bearing material was 6.7 N / mm ² . The porosity of the porous sintered metal layer 4 of this bearing material is shown in FIG.

  Next, the inner surface of the porous sintered metal layer 4 is ground, and the porous sintered metal layer 4 having a bearing surface 8 and having a thickness of 1.7 mm is provided on the inner surface 9 of the cylindrical backing metal 2. A static pressure gas radial bearing 1 was obtained.

Example 2
Similar to the first embodiment, the annular groove 6, the groove 7, and the hole 5 are provided, and the nickel plating layer having a thickness of 3 μm is formed on the inner surface 9 excluding the grooves 6, 7 and the hole 5, and the surface of the nickel plating layer is thick. A cylindrical back metal 2 having two plating layers of a 15 μm copper plating layer was prepared.

  8% by weight of atomized tin powder passing through a 250 mesh screen, 28% by weight of electrolytic nickel powder passing through a 250 mesh screen, and 2.0% copper phosphorus (phosphorus 14.5%) powder passing through a 120 mesh screen 5% by weight of graphite powder (inorganic substance particles) passing through a 150 mesh sieve and the remainder of the electrolytic copper powder passing through a 150 mesh sieve are mixed for 5 minutes with a V-type mixer to obtain a mixed powder (copper: 58.71 wt%, tin: 8 wt%, nickel: 28 wt%, phosphorus: 0.29 wt%, graphite: 5 wt%).

Hereinafter, the bearing for the porous static pressure gas radial bearing 1 in which the porous sintered metal layer 4 is integrally joined to the inner surface 9 of the cylindrical back metal 2 via the joining layer 3 in the same manner as in the first embodiment. I got the material. The joining strength (shear strength) between the backing metal 2 and the porous sintered metal layer 4 integrally joined to the inner surface 9 of the backing metal 2 in this bearing material was 7.2 N / mm ² . The porosity of the porous sintered metal layer 4 of this bearing material is shown in FIG. Next, the inner surface of the porous sintered metal layer 4 is ground, and the porous sintered metal layer 4 having a bearing surface 8 and having a thickness of 1.7 mm is provided on the inner surface 9 of the cylindrical backing metal 2. A static pressure gas radial bearing 1 was obtained.

Example 3
Similar to the first embodiment, the annular groove 6, the groove 7 and the hole 5 are provided, and the nickel plating layer having a thickness of 10 μm is formed on the inner surface 9 excluding the grooves 6, 7 and the hole 5, and the thickness is formed on the surface of the nickel plating layer. A cylindrical backing metal 2 having two plating layers with a 20 μm copper plating layer was prepared.

  8% by weight of atomized tin powder passing through a 250 mesh screen, 28% by weight of electrolytic nickel powder passing through a 250 mesh screen, and 3.0% of copper phosphorus (phosphorus 14.5%) powder passing through a 120 mesh screen 5% by weight of graphite powder (inorganic substance particles) passing through a 150 mesh sieve and the remainder of the electrolytic copper powder passing through a 150 mesh sieve are mixed for 5 minutes with a V-type mixer to obtain a mixed powder (copper: 58.58 wt%, tin: 8 wt%, nickel: 28 wt%, phosphorus: 0.42 wt%, graphite: 5 wt%).

Hereinafter, the bearing for the porous static pressure gas radial bearing 1 in which the porous sintered metal layer 4 is integrally joined to the inner surface 9 of the cylindrical back metal 2 via the joining layer 3 in the same manner as in the first embodiment. I got the material. The joining strength (shear strength) between the backing metal 2 and the porous sintered metal layer 4 integrally joined to the inner surface 9 of the backing metal 2 in this bearing material was 7.0 N / mm ² . The porosity of the porous sintered metal layer 4 of this bearing material is shown in FIG. Next, the inner surface of the porous sintered metal layer 4 is ground, and the porous sintered metal layer 4 having a bearing surface 8 and having a thickness of 1.7 mm is provided on the inner surface 9 of the cylindrical backing metal 2. A static pressure gas radial bearing 1 was obtained.

Comparative Example 1
A cylindrical backing metal made of carbon steel for machine structure (S45C) having an inner diameter of 30 mm, an outer diameter of 45 mm, and a length of 30 mm is prepared, and the inner surface of the cylindrical backing metal is equidistantly spaced along the axial direction of the backing metal. Three annular grooves each having a diameter of 2 mm and a depth of 2 mm are formed, and one communicating groove along the axial direction of the back metal that connects the annular grooves to each other, and is opened from the outer surface of the back metal to the communicating groove. One supply hole was formed.

  8% by weight of atomized tin powder that passes through a 250 mesh screen, 28% by weight of electrolytic nickel powder that passes through a 250 mesh screen, and 4.0% of copper phosphorus (phosphorus 14.5%) powder that passes through a 120 mesh screen 5% by weight of graphite powder (inorganic substance particles) passing through a 150 mesh sieve and the remainder of the electrolytic copper powder passing through a 150 mesh sieve are mixed for 5 minutes with a V-type mixer to obtain a mixed powder (copper: 58.42 wt%, tin: 8 wt%, nickel: 28 wt%, phosphorus: 0.58 wt%, graphite: 5 wt%).

  Thereafter, in the same manner as in Example 1, a bearing material for a porous static pressure gas radial bearing in which a porous sintered metal layer was integrally bonded to the inner surface of a cylindrical back metal was obtained. The porosity of the porous sintered metal layer of this bearing material is shown in FIG. Next, a porous static pressure gas radial bearing in which the inner surface of the porous sintered metal layer is ground and a 1.7 mm thick porous sintered metal layer having a bearing surface is provided on the inner surface of the cylindrical backing metal. Got.

Comparative Example 2
A cylindrical backing metal similar to that of Comparative Example 1 was prepared.

  8% by weight of atomized tin powder passing through a 250 mesh screen, 28% by weight of electrolytic nickel powder passing through a 250 mesh screen, and 7.0% copper phosphorus (phosphorus 14.5%) powder passing through a 120 mesh screen 5% by weight of graphite powder (inorganic substance particles) passing through a 150 mesh sieve and the remainder of the electrolytic copper powder passing through a 150 mesh sieve are mixed for 5 minutes with a V-type mixer to obtain a mixed powder (copper: 57.98 wt%, tin: 8 wt%, nickel: 28 wt%, phosphorus: 1.02 wt%, graphite: 5 wt%).

  Thereafter, in the same manner as in Example 1, a bearing material for a porous static pressure gas radial bearing in which a porous sintered metal layer was integrally bonded to the inner surface of a cylindrical back metal was obtained. The porosity of the porous sintered metal layer of this bearing material is shown in FIG. Next, a porous static pressure gas radial bearing in which the inner surface of the porous sintered metal layer is ground and a 1.7 mm thick porous sintered metal layer having a bearing surface is provided on the inner surface of the cylindrical backing metal. Got.

By measuring the open flow rate (Nl / hr) of the bearing material obtained in Examples 1 to 3 and Comparative Examples 1 and 2 above and the open flow rate of the porous hydrostatic gas radial bearing, respectively, the flow rate ratio (porous The open flow rate of the hydrostatic gas radial bearing / the open flow rate of the bearing material was investigated. The open flow rate is measured by introducing compressed air with a supply pressure of 5 kg / cm ² from each bearing material and the supply hole of the porous static pressure gas radial bearing, and 1 hour of compressed air flowing through the porous sintered metal layer. The per unit flow rate (Nl / hr) was measured.

  FIG. 7 shows the open flow rate of the porous hydrostatic gas radial bearing and the bearing material obtained in Examples 1 to 3 and Comparative Examples 1 and 2, and the ratio thereof (opening of the porous hydrostatic gas radial bearing). It is a graph showing the flow rate / opening flow rate of the bearing material. From this figure, it can be seen that the flow rate ratio increases with the amount of the phosphorus component in the component forming the porous sintered metal layer being 0.5 wt%.

Next, with respect to the porous static pressure gas radial bearings of Examples 1 to 3 and Comparative Examples 1 and 2 showing the above flow ratio, compressed air having a supply pressure of 5 kg / cm ² was introduced from the supply hole. The flying height (μm) of the shaft inserted into the bearing surface of the radial bearing by the compressed air flowing through the porous sintered metal layer was examined.

  FIG. 8 is a graph showing the relationship between the load load (kgf) and the flying height in the porous hydrostatic gas radial bearings of Examples 1 to 3 and Comparative Examples 1 and 2. From this graph, the porous hydrostatic gas radial bearing 1 of Examples 1 to 3 has a higher flying height than the porous hydrostatic gas radial bearings of Comparative Example 1 and Comparative Example 2 at any load. I understand.

  From the results of FIG. 8, the open flow rates of the porous hydrostatic gas radial bearing 1 of Examples 1 to 3 and the porous hydrostatic gas radial bearings of Comparative Examples 1 and 2 are almost the same (see FIG. 7). In spite of the fact that the porous hydrostatic gas radial bearing 1 of each example has a larger flying height than the porous hydrostatic gas radial bearing of each comparative example, the pores of the bearing material of each example and comparative example This is presumably due to the large number of rates (see FIG. 6). That is, the porosity of the porous sintered metal layer 4 in the bearing material of each example exceeds 30%, and the compressed gas introduced from the holes 5 is distributed through the inside of the porous sintered metal layer 4. Since the pressure loss is small, the pressure of the supply air ejected to the bearing surface 8 is relatively increased, and the ejection of the supply air to the bearing surface 8 extends over the entire surface of the porous sintered metal layer 4, thereby increasing the flying height. Inferred to increase. On the other hand, the porosity of the porous sintered metal layer in the bearing material of each comparative example is 21 to 22%, and a large amount of air supply to the bearing surface is generated in the communication groove portion. It is presumed that the supply of air to the bearing surface is unbalanced because the supply of air from the sintered metal layer is extremely small.

  In the porous hydrostatic gas radial bearing 1 shown in FIG. 1 and FIG. 2, the grooves 7 for mutual communication are opened on the inner surface 9 side and provided in the back metal 2, but instead, it is shown in FIG. 9 to FIG. Thus, the dead end hole 21 extends in the axial direction from one annular end face 22 in the axial direction of the back metal 2 toward the other annular end face 23 and is provided in the inside of the back metal 2 so that the annular grooves 6 communicate with each other. Even in the porous static pressure gas radial bearing 1 having such a dead end hole 21 for communication, the porous sintered metal layer 4 has openings of the annular grooves 6 on the inner surface 9 side of the back metal 2. The cover is covered and integrated with the cylindrical inner surface 9 of the back metal 2 via the bonding layer 3, and the cylindrical inner surface of the porous sintered metal layer 4 is a bearing surface 8.

  The porous hydrostatic gas radial bearing 1 shown in FIGS. 9 to 12 also has a cylindrical outer surface 25 in the radial direction of the back metal 2 so as to constitute a compressed gas supply means together with the dead end hole 21 and the annular groove 6. It further has a dead hole 26 for supplying a compressed gas provided in the inside of the back metal 2 that extends in the radial direction from the outer surface 25 of the back metal 2 toward the dead hole 21 for mutual communication. .

  One end 27 in the axial direction of the dead end hole 21 opened at the end face 22 of the back metal 2 is provided with a thread groove 29 as a fitting means for fitting the stopper 28, and the axial end of the dead end hole 21 in the axial direction is provided. The other end 30 is closed by the back metal 2 itself before the end face 23 of the back metal 2, and is communicated with the dead end hole 26, and the plug 28 screwed into the screw groove 29 and fitted to the one end 27 is One end 27 is closed, and the dead end hole 26 communicates with the dead end hole 21 and the annular groove 6.

  According to the radial bearing material for the porous hydrostatic gas radial bearing 1 shown in FIGS. 9 to 12, the same effect as the above radial bearing material can be obtained, and the inner surface 9 side of the back metal 2 does not open. Thus, since the dead end holes 21 for communicating the annular grooves 6 with each other are provided inside the back metal 2, the porous firing through the inner surface 9 of the back metal 2 directly from the dead hole 21. As a result of being able to avoid the supply of the compressed gas to the bonded metal layer 4 and supplying the compressed gas supplied to the dead end hole 21 to the porous sintered metal layer 4 through each of the annular grooves 6, the porous Since the compressed gas can be ejected substantially uniformly from the surface of the sintered metal layer 4, that is, the bearing surface 8, and the dead hole 21 for mutual communication is provided inside the back metal 2, such a dead end is provided. Hole 21 is drilled from the end face 22 of the back metal 2 using a drill or the like. To be formed, it is very excellent in manufacturability as compared with the formation of intercommunicating Spoken groove 7 of the inner surface 9.

  Further, in the radial bearing material for the porous hydrostatic gas radial bearing 1 shown in FIGS. 9 to 12, the back metal 2 is formed integrally with the cylindrical portion 31 and the cylindrical portion 31 as shown in FIGS. It may be configured with the portion 32, and a flanged radial bearing material may be configured by providing a dead end hole 26 for supplying compressed gas in the flange portion 32. The radial bearing material for the porous hydrostatic gas radial bearing 1 shown in FIGS. 13 and 14 is also compressed from the surface of the porous sintered metal layer 4, that is, the bearing surface 8, similarly to those shown in FIGS. 9 to 12. Gas can be ejected substantially evenly, and the dead end hole 21 can be easily formed from the end face 22 of the cylindrical portion 31 of the back metal 2 using a drill or the like, and is extremely excellent in manufacturability. The porous sintered metal can be firmly joined and integrated without peeling or the like between the layer 4 and the stainless steel back metal 2 and the porosity of the porous sintered metal layer 4 can be increased. The flying height by the compressed gas flowing through the layer 4 can be increased.

DESCRIPTION OF SYMBOLS 1 Porous static pressure gas radial bearing 2 Back metal 3 Joining layer 4 Porous sintered metal layer

Claims (30)

  A back metal made of stainless steel and a porous sintered metal layer integrated on at least one surface of the back metal through a bonding layer, and inorganic substance particles at grain boundaries of the porous sintered metal layer Is a porous material for a porous hydrostatic gas bearing, in which a porous sintered metal layer containing inorganic particles is composed of 4 wt% or more and 10 wt% or less of tin and 10 wt% or more A bearing material for a porous hydrostatic gas bearing, characterized by comprising 40% by weight or less of nickel, 0.1% by weight or more and less than 0.5% by weight of phosphorus, and the balance being copper.   The bearing material for a porous hydrostatic gas bearing according to claim 1, wherein the inorganic substance particles are contained in the porous sintered metal layer in a proportion of 2 wt% to 10 wt%.   The inorganic substance particle is composed of at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Bearing material.   The back metal is formed in a cylindrical shape, and the porous sintered metal layer containing inorganic substance particles in a dispersed manner is integrated on one cylindrical surface of the back metal via a bonding layer. A bearing material for a porous hydrostatic gas bearing according to any one of the above.   The backing metal is formed in a flat plate shape, and the porous sintered metal layer containing dispersed inorganic substance particles is integrated with one flat plate surface of the backing metal via a bonding layer. A bearing material for a porous hydrostatic gas bearing according to any one of the above.   The bonding layer includes at least a nickel plating layer, and the nickel plating layer is bonded to at least one surface of the back metal, for a porous hydrostatic gas bearing according to any one of claims 1 to 5. Bearing material.   The bonding layer includes two plating layers, a nickel plating layer and a copper plating layer. The nickel plating layer is bonded to at least one surface of the back metal, and the porous sintered metal layer is a copper plating. The bearing material for a porous hydrostatic gas bearing according to any one of claims 1 to 5, wherein the bearing material is bonded to the layer.   The bearing material for a porous hydrostatic gas bearing according to claim 7, wherein the copper plating layer is bonded to the surface of the nickel plating layer.   The bearing material for a porous hydrostatic gas bearing according to claim 7 or 8, wherein the copper plating layer has a thickness of 10 µm to 25 µm.   The bearing material for a porous hydrostatic gas bearing according to claim 7 or 8, wherein the copper plating layer has a thickness of 10 µm or more and 20 µm or less.   The bearing material for a porous hydrostatic gas bearing according to any one of claims 6 to 10, wherein the nickel plating layer has a thickness of 2 µm to 20 µm.   The bearing material for a porous hydrostatic gas bearing according to any one of claims 6 to 10, wherein the nickel plating layer has a thickness of 3 µm or more and 15 µm or less.   A porous hydrostatic gas bearing using the bearing material according to any one of claims 1 to 12, wherein a compressed gas is supplied to a porous sintered metal layer containing dispersed inorganic substance particles on a back metal. A porous hydrostatic gas bearing provided with means for performing.   A back plate made of stainless steel and having a cylindrical inner surface, a plurality of annular grooves provided on the inner surface side of the back metal side by side in the axial direction, and the plurality of annular grooves. In order to communicate with each other, a dead end hole extending in the axial direction from one annular end surface of the back metal toward the other annular end surface and provided inside the back metal, and each annular groove on the inner surface side of the back metal And a cylindrical porous sintered metal layer integrated with a cylindrical inner surface of a back metal via a bonding layer, and a bearing material for a porous hydrostatic gas radial bearing.   One end of the dead end hole for mutual communication is opened at the annular end face of the back metal, and the other end of the dead end hole for mutual communication is closed by the back metal itself before the other annular end face of the back metal. The bearing material for the porous static pressure gas radial bearing according to claim 14.   The bearing material for a porous hydrostatic gas radial bearing according to claim 15, further comprising fitting means for fitting a plug that closes one end of a dead end hole for mutual communication.   The bearing material for a porous hydrostatic gas radial bearing according to claim 16, wherein the fitting means includes a thread groove.   And further comprising a dead hole for supplying a compressed gas provided in the inside of the back metal that extends in the radial direction from the outer surface of the back metal toward the dead hole for mutual communication. Item 18. A bearing material for a porous hydrostatic gas radial bearing according to any one of Items 14 to 17.   The porous sintered metal layer contains grain boundaries of sintered metal containing tin, nickel, phosphorus and copper, and inorganic substance particles dispersed in the grain boundaries of the sintered metal. A bearing material for a porous hydrostatic gas radial bearing according to any one of the above.   The grain boundaries of the sintered metal are 4 wt% to 10 wt% tin, 10 wt% to 40 wt% nickel, 0.1 wt% to less than 0.5 wt% phosphorus, and the balance 20. The bearing material for a porous static pressure gas radial bearing according to claim 19, which contains copper.   The bearing material for a porous hydrostatic gas radial bearing according to claim 19 or 20, wherein the inorganic substance particles are contained in a ratio of 2 wt% to 10 wt%.   The porous material according to any one of claims 19 to 21, wherein the inorganic substance particles comprise at least one of graphite, boron nitride, graphite fluoride, calcium fluoride, aluminum oxide, silicon oxide, and silicon carbide. Bearing material for pressurized gas radial bearings.   The porous static pressure gas radial bearing according to any one of claims 14 to 22, wherein the bonding layer includes at least a nickel plating layer, and the nickel plating layer is bonded to the cylindrical inner surface of the back metal. Bearing material.   The bonding layer includes two plating layers, a nickel plating layer and a copper plating layer formed on the surface of the nickel plating layer. The nickel plating layer is bonded to the cylindrical inner surface of the back metal and is porous. 24. The bearing material for a porous hydrostatic gas radial bearing according to claim 14, wherein the sintered metal layer is joined to the copper plating layer.   The bearing material for a porous hydrostatic gas radial bearing according to claim 24, wherein the copper plating layer has a thickness of 10 µm or more and 25 µm or less.   The bearing material for a porous hydrostatic gas radial bearing according to claim 24, wherein the copper plating layer has a thickness of 10 µm or more and 20 µm or less.   The bearing material for a porous static pressure gas radial bearing according to any one of claims 23 to 26, wherein the nickel plating layer has a thickness of 2 µm or more and 20 µm or less.   27. The bearing material for a porous hydrostatic gas radial bearing according to claim 23, wherein the nickel plating layer has a thickness of 3 μm or more and 15 μm or less.   A porous static pressure gas radial bearing using the bearing material according to any one of claims 14 to 28.   30. The porous hydrostatic gas radial bearing according to claim 29, wherein a plug for closing the one end is fitted to one end of the dead end hole for mutual communication.

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