WO2006114849A1

WO2006114849A1 - Miniature bearing and method for manufacturing the same

Info

Publication number: WO2006114849A1
Application number: PCT/JP2005/007048
Authority: WO
Inventors: Yoshimitsu Kankawa; Hiroshi Setowaki; Hiroshi Satomi; Motoi Fukuda
Original assignee: Mold Research Co., Ltd
Priority date: 2005-04-12
Filing date: 2005-04-12
Publication date: 2006-11-02

Abstract

A miniature porous bearing having good dimensional accuracy is provided. A method for manufacturing a miniature bearing having an outer diameter of 2 mm or less and an inner diameter of 1 mm or less, which comprises a step of adding an organic binder to a powder of a metal or a ceramic, to prepare a composition for forming, a step of preparing a primary formed product by pressing, extrusion or injection using the above composition for forming, a step of inserting the above primary formed product into a heated press mold, followed by pressing, to thereby prepare a secondary formed product, and a step of degreasing and then sintering the above secondary formed product, to thereby prepare a sintered article.

Description

Ultra-compact bearing and manufacturing method thereof

Technical field

The present invention relates to a microporous bearing and a method for manufacturing the same.

Background art

[0002] Conventionally, in the manufacture of oil-impregnated bearings, a powder sintering method in which powder is compressed and sintered has been used. Currently, small oil-impregnated bearings are generally manufactured by filling a mold with powder coated with a binder and pressing it to produce a green compact and adjusting the sintering temperature.

Disclosure of the invention

Problems to be solved by the invention

[0003] However, with the conventional powder sintering method, it is difficult to stably fill the mold with powder material when trying to manufacture ultra-compact bearings with an outer diameter of 2 mm or less and an inner diameter of 1 mm or less. There is a problem that there is. In addition, because of the ultra-small size, it is difficult to manufacture such a bearing with dimensional accuracy, and sizing is indispensable. In addition, when the product thickness is reduced, the product strength is reduced and the product may crack. In powder sintering, the pressure on the mold surface increases during compacting. When the thickness of the compact becomes less than lmm, the powder on the compact surface is deformed by the pressure, and the desired pore size is exceeded. There is a problem that becomes smaller.

[0004] The present invention has been made in consideration of the problems in the prior art as described above, and has a high dimensional accuracy, especially a micro bearing having a small dimensional accuracy, and does not generate cracks. It is an object of the present invention to provide a porous bearing having a desired porosity and a method by which such a bearing can be manufactured without sizing.

Means for solving the problem

[0005] The present invention relates to a method for producing a micro bearing having an outer diameter of 2 mm or less and an inner diameter of 1 mm or less, which is a metal powder having an average particle diameter of 1 to 150 μm or a ceramic having an average particle diameter of 0.1 to 10 μm. powder A process for producing a molding composition containing a powder and an organic noinda, wherein the content of the organic binder is 30 to 70 vol%,

A step of producing a primary molded body by press molding, extrusion molding or injection molding using the molding composition;

Inserting the primary molded body into a heated press mold and applying pressure to produce a secondary molded body,

Degreasing and sintering the secondary molded body to produce a sintered body,

A method for producing a microporous bearing characterized in that

It is.

[0006] An organic binder of 30 to 70 vol% (vol% with respect to the total amount of the molding composition) is added to metal powder having an average particle size of 1 to 150 m or ceramic powder having an average particle size of 0.1 to 10 / zm. By using a deformed molding composition, it is possible to maintain the strength and porosity of the bearing within a desired range, and the molding composition can be smoothly fed into a molding machine.

A primary molded body is produced using the molding composition, and then the primary molded body is inserted into a heated press mold and pressed to obtain a conventional molded body (press molding, extrusion molding and injection molding). It is possible to obtain a secondary molded body having a higher dimensional accuracy than a molded body obtained by only the process.

By degreasing and sintering the secondary compact, it is possible to manufacture an ultra-small porous bearing having a desired porosity with high dimensional accuracy. Furthermore, even when the thickness of the product is less than lmm, it is possible to manufacture a bearing that has high product strength and is less prone to cracking.

[0007] In producing the molding composition, 1 to 3 Ovol% (vol% with respect to the total amount of the molding composition) of thermosetting resin having an average particle size of 10 to 150 μm is added to obtain desired pores. The rate can be further increased.

[0008] With the method according to the present invention, a metal or ceramic micro bearing having a weight of 0.1 lg or less, an outer diameter of 2 mm or less, an inner diameter of 1 mm or less, and an inner dimensional accuracy of ± 0. Furthermore, it is a micro or small bearing made of metal or ceramics with a weight of 0.1 lg or less, an outer diameter of 1.5 mm or less, an inner diameter of 0.7 mm or less, and an inner diameter dimensional accuracy of ± 0.005 mm or less. Therefore, it is possible to manufacture with high dimensional accuracy.

[0009] It is also possible to produce a micro bearing having a porosity of 15 vol% or more, and to produce a bearing having a flange with an outer diameter of the flange of 2 mm or less. It is also possible to make these bearings impregnated with bearing oil to form oil-impregnated bearings.

The invention's effect

[0010] According to the present invention, even an ultra-small porous bearing having an outer diameter of 2 mm or less and an inner diameter of 1 mm or less can be manufactured with very high dimensional accuracy.

Brief Description of Drawings

FIG. 1 is a process diagram showing a production method according to the present invention.

FIG. 2A is a diagram showing an embodiment of a micro bearing according to the present invention, and FIG. 2B is a micro bearing according to the present invention, which is an embodiment of a bearing having a flange. FIG. BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, a method for manufacturing a bearing according to the present invention will be described. FIG. 1 shows a process for producing a microporous bearing according to the present invention, and a molded body cross-sectional model in each process.

[0013] First, an organic binder and, if necessary, a thermosetting resin powder to increase the porosity are added to the metal powder or ceramic powder that is the raw material powder, and the mixture is heated and kneaded using a heating kneader. As a result, a molding composition in which each material is uniformly dispersed is obtained.

As for the metal powder, two or more kinds of powders having an average particle diameter of 1 to 150 μm and different average particle diameters may be mixed. For ceramic powder, the average particle size is 0.1 ~: LO / z m.

V, Two or more powders with different average particle sizes may be mixed.

The powder used is not particularly limited. For metal powder, copper, silver, gold, iron, nickel

One or more of chromium, conoretole, tungsten, anoremi, titanium, manganese, or an alloy containing one or more of these metals can be used.

As the ceramic powder, a powder having one or more kinds of carbides, nitrides and oxides containing aluminum, titanium, tungsten, silicon, zircon, calcium and magnesium as elements can be used.

[0014] When the powder has a small average particle diameter, the powder per unit volume in the molding composition The percentage of the end increases. Therefore, the filling rate of the powder into the thin wall portion can be increased, and the strength of the thin wall portion after sintering can be increased. On the other hand, if the average particle size is too small, the strength of the bearing increases, but the sintered density increases, making it difficult to ensure the desired porosity. Furthermore, if the average particle size of the powder is too small, it becomes difficult to put the molding composition into the molding machine during molding, and the molding composition does not smoothly enter the molding machine. Stability during molding decreases. On the other hand, if the average particle size of the powder is too large, the filling rate of the powder in the thin-walled portion will be low, which may reduce the strength of the bearing after sintering.

The average particle size of the metal powder used in the present invention is preferably 1 to 150 m, more preferably 10 to 50 m. The average particle size of the ceramic powder used in the present invention is preferably 0.1 to 10 μm, more preferably 0.5 μm to 5 μm.

[0015] Further, the content of the metal or ceramic powder to be used is preferably 30 to 70 vol%, more preferably 30 to 70 vol% of the entire molding composition. If the content is less than the lower limit, the dimensional accuracy after degreasing and sintering may be reduced.

[0016] Examples of the organic binder include: polyolefins such as polyethylene, polypropylene, and ethylene acetate copolymer; acrylic resins such as polymethyl methacrylate and polybutyl methacrylate; and styrene resins such as polystyrene. And various types of waxes, paraffins, higher fatty acids (eg, stearic acid), higher alcohols, higher fatty acid esters, higher fatty acid amides, etc. Species or a mixture of two or more can be used.

[0017] The content of the organic binder is preferably 30 to 70 vol% of the entire molding composition, more preferably 35 to 60 vol%. If the content is less than the lower limit value, the molding pressure may not be sufficiently transmitted, and the filling of the thin portion may be insufficient. On the other hand, if the content exceeds the upper limit value, the dimensional accuracy may decrease or the shape may be deformed after degreasing and sintering.

In order to further increase the desired porosity, a thermosetting resin powder having an average particle size of 10 to 150 μm may be added in addition to the powder and the organic binder to produce a molding composition. preferable. The content of thermosetting resin is preferably 1-30 vol% of the entire molding composition. More preferably, it is 1 to 15 vol%.

Examples of the thermosetting resin used include epoxy resin, urethane resin, melamine resin, and phenol resin. From the viewpoint of thermal decomposability, epoxy resin and urethane resin are preferable.

These thermosetting resins behave as powders in the same manner as metal powders and ceramic powders that are used without being melted when the materials are kneaded. Since these thermosetting resin decomposes and disappears with the decomposition of the organic binder during the degreasing process, pores corresponding to the volume of the added thermosetting resin occur after the degreasing process. Since the pores are retained even after sintering, the porosity increases as the amount added increases. If the amount of thermosetting resin added exceeds the upper limit, the amount of pores will increase and the strength after sintering will decrease. Also, the improvement in porosity expected when the amount added is below the lower limit is not observed.

[0019] The kneading conditions of the molding composition vary depending on various conditions such as the composition and particle size of the powder used, the composition of the organic binder, the composition and shape of the thermosetting resin to be added, and the blending amount thereof. For example, the kneading temperature can be about 100 to 250 ° C., and the kneading time can be about 30 to 120 minutes. The molding composition requires different shapes depending on the molding method. In the case of press forming, the obtained molding composition is pulverized to have an average particle size of about 50 to about LOO m. A pulverizer such as a pin disk or a hammer mill is suitable for the pulverizer used at this time. In extrusion molding and injection molding, pellets (small lumps) are formed as necessary. The particle size of the pellet can be set to about 1 to 15 mm, for example.

[0020] Next, using the molding composition, a primary molded body having a desired shape and size is produced by press molding, extrusion molding or injection molding. In the production of the primary compact, the dimensions and shape of the mold are determined in anticipation of the dimensional shrinkage after sintering. The molding method can be selected according to the desired product shape. In particular, injection molding is desirable when forming a molded body having a complicated shape.

In the press molding, a molding composition pulverized to an average particle size of 50 to LOO μm is put into a mold and compression molding is performed. At this time, depending on the shape of the product to be produced, a primary compact is produced by applying a molding pressure of about 1 to 50 tons.

In injection molding, a molding composition is injection-molded by an injection molding machine to obtain a desired shape and size. A primary molded body is produced. In this case, a molded body having a complicated and fine shape can be easily manufactured by selecting a molding die. The molding conditions for injection molding vary depending on various conditions such as the composition and particle size of the powder used, the composition of the organic binder, the composition of the thermosetting resin to be added, and the amount of these blended, but the molding temperature is preferably 100 to 100. About 200 ° C, and the injection pressure is preferably about 300 to 1000 kgfZcm ² .

In extrusion molding, extrusion molding is performed using a mold having a desired shape by an extruder. The molding composition temperature is determined by the cross-sectional shape of the product, preferably 50-200 ° C. Preferably, the pressure is 50~500kgf Zcm ^2.

[0022] The primary molded body obtained by the above press molding, injection molding, and extrusion molding is inserted into a heated press mold in order to increase the dimensional accuracy, and pressed to produce a secondary molded body. By this process, the dimensional accuracy of the molded body can be increased. Compared with conventional molded bodies (molded bodies obtained only by the press molding, extrusion molding and injection molding processes), the dimensional accuracy is high. Can be obtained.

[0023] The pressing conditions for obtaining the secondary compact can be changed depending on the shape of the compact. The mold temperature during pressing is preferably 50 to 150 ° C. When the heating temperature is 180 ° C or higher, the cooling time after pressing becomes longer and the productivity decreases. On the other hand, when the heating temperature is 50 ° C or less, it is difficult to ensure the dimensions of the secondary molded body defined by the press mold.

[0024] molding pressure for obtaining a secondary molded article around 100～1500KgfZcm ² is desirable. If it is higher than 200 OkgfZcm ² , the internal stress increases, which may cause problems such as cracking and deformation after molding or after degreasing and sintering. In addition, if the molding pressure is lower than lOkgfZcm ² , the secondary compact may deviate from the dimensions specified in this pressing process.

[0025] The secondary molded body after pressing is cooled and taken out in a mold. The temperature during removal is preferably 10 to 80 ° C. When the temperature at the time of taking out becomes lower than the predetermined temperature, the cooling shrinkage becomes large, and cracks may occur at the time of taking out. When the temperature at the time of taking out becomes higher than a predetermined temperature, the molded body is insufficiently cooled, so that the secondary molded body may be deformed and dimensional accuracy may be lowered.

[0026] The secondary molded body obtained by the above-described method is excellent in dimensional accuracy, and is in a state where the organic binder and the thermosetting resin added as needed are uniformly dispersed in the powder. [0027] In the process of degreasing the organic noda !, the maximum degreasing temperature is preferably 400 ° C or higher. When the maximum degreasing temperature is 300 ° C or less, the organic binder and thermosetting resin are not sufficiently decomposed and remain as carbides, which may cause defects such as cracks in the sintered product.

In the degreasing step, the degreasing atmosphere is determined according to the compositional components of the powder used. The optimum degreasing temperature is 400 ° C to 800 ° C. If there is residual carbon resulting from the organic binder and the added thermosetting resin after degreasing, the maximum temperature in hydrogen is 800 ° C. Reduction treatment is performed to remove residual carbon.

[0028] The obtained degreased body is sintered by adjusting the sintering temperature according to the powder used so that the porosity becomes 10 to 50 vol%. The sintering conditions vary depending on the powder material used. 1000-1400 ° C for stainless steel materials, 900-1200 ° C for titanium materials, 700-00 for copper materials: L100 ° C, 1000-1000 for iron materials 1400 ° C is desirable. For these metals, nitrogen, argon, vacuum, or hydrogen is used as the sintering atmosphere as required.

Also, the sintering conditions differ depending on the powder used in ceramics: 1300-1700 for alumina and 1000-1500 for zirconia. . Sintered with. By the above sintering step, powder diffusion and grain growth proceed, and the sintering density increases.

[0029] The porosity of the obtained sintered body is preferably 10 to 50 vol%, more preferably 12 to 40 vol%, and particularly preferably 15 to 40 vol%. If the porosity is too low, the oil content decreases and the desired function as a bearing cannot be obtained. Also, if the porosity is too high, the mechanical strength may decrease.

By sintering the product obtained by this production method at a higher temperature, it is possible to produce a denser sintered part with excellent dimensional accuracy.

[0030] In the present invention, when the bearing is not in a single cylinder shape (a cylindrical shape in which the inner diameter and the outer diameter are constant at all positions), the inner diameter of the bearing in the present invention is the narrowest part of the bearing hollow portion. The outer diameter of the bearing refers to the outer diameter of the narrowest part in the outer shape of the bearing. If the bearing has multiple flanges, the outer diameter of the flange refers to the outer diameter of the smallest flange.

Next, the method for manufacturing the bearing of the present invention will be described with reference to examples. Example 1

[0032] Iron making of small shaft

The bearing shown in FIG. 2A was produced using the method according to the present invention.

Stainless steel powder (SUS316L) was used as the metal powder. A powder with an average particle size of 10 / z m was used.

As the organic binder, a mixture in which polystyrene, polybutylmethallate, ethylene acetate butyl copolymer, and raffin wax were mixed at a ratio of 15: 15: 20: 50 was used.

The composition of the molding composition was 65 vol% stainless powder + 35 vol% organic binder. The powder and organic binder are kneaded using a heat kneader at 160 ° C for 1 hour, and the resulting kneaded product is pulverized using a hammer mill, and sifted to force a particle size of 50 to LOO μm. I made a thing.

The molding composition obtained by sieving was molded at a pressure of 5000 kgf / cm ² using a pressure press machine to obtain a primary molded body. The mold used had an outer diameter of 1.2 mm, an inner diameter of 0.6 mm, and a height of 1.867 mm.

The primary molded body obtained by the above press molding is inserted into a press mold (mold size: outer diameter 1.3 mm, inner diameter 0.5 mm, height 1.4 mm), and heated and pressure press molded, A secondary molded body was obtained. The molding conditions were a pressure of 800 kgf / cm ² , a mold temperature of 100 ° C, and when the compact was cooled to 50 ° C, it was removed from the press die.

The obtained secondary compact was degreased at a maximum temperature of 500 ° C · nitrogen atmosphere, and the degreased compact was sintered at a maximum temperature of 1100 ° C · argon atmosphere.

The product (bearing) weight obtained was 0. Olg.

In order to make an oil-impregnated bearing by impregnating the pores of the obtained bearing with bearing oil, the bearing is immersed in lubricating oil, placed in a vacuum furnace, the inside of the furnace is evacuated, and placed in the furnace for 30 minutes. Was confirmed to be impregnated and removed from the furnace.

Example 2

[0033] Steelmaking of extra-small invited shafts

The bearing shown in FIG. 2A was produced using the method according to the present invention. Stainless steel powder (SUS316L) was used as the metal powder. A powder with an average particle size of 10 / zm was used.

In order to increase the porosity, urethane resin having an average particle size of 30 m was used as a thermosetting resin.

As the organic binder, a mixture in which polyacetal, polypropylene, and paraffin wax were mixed at a ratio of 25:25:50 was used.

The composition of the molding composition was stainless powder 55 vol% + urethane resin 1 Ovol% + organic binder 35 vol%.

Stainless steel powder, organic binder, and urethane resin are kneaded using a heating kneader at 160 ° C for 1 hour, and the resulting kneaded product is pulverized using a nonmmer mill and sieved to give a particle size of 50 to 100 μm. A molding composition was prepared.

The primary molded body obtained by the above press molding is inserted into a press mold (mold size: outer diameter 1.3 mm, inner diameter 0.5 mm, height 1.4 mm), and heated and pressure press molded, A secondary molded body was obtained. The molding conditions were a pressure of 800 kgf / cm ² and a mold temperature of 90 ° C. When the compact was cooled to 50 ° C, it was removed from the press die.

The obtained secondary compact was degreased at a maximum temperature of 500 ° C. · nitrogen atmosphere, and the degreased compact was sintered at a maximum temperature of 1250 ° C. under an argon atmosphere.

The product (bearing) weight obtained was 0. Olg.

Example 3

More M / 1 ヽ

In addition, a urethane resin having an average particle size of 30 m force was used as a thermosetting resin for increasing the porosity. As the organic binder, a mixture in which polyacetal, polypropylene, and paraffin wax were mixed at a ratio of 25:25:50 was used.

Stainless steel powder, organic binder and urethane resin were kneaded using a heat kneader at 160 ° C. for 1 hour, and the obtained kneaded product was made into pellets having a length of 1 to 5 mm using a granulator.

Injection molding was performed using the obtained pellets. Molding was performed at a molding temperature of 180 ° C, a molding pressure of 1000 kgf / cm ² , an injection speed of 30 mm / min, and a mold temperature of 30 ° C to obtain a primary molded body. The mold used was an outer diameter of 1.2 mm, an inner diameter of 0.6 mm, and a height of 1.867 mm.

The primary molded body obtained by the above injection molding is inserted into a press die (die size: outer diameter 1.3 mm, inner diameter 0.5 mm, height 1.4 mm), and heated and pressed under pressure. The next molded body was obtained. The molding conditions were a pressure of 800 kgf / cm ² and a mold temperature of 80 ° C. When the compact was cooled to 40 ° C, it was removed from the press die.

The product (bearing) weight obtained was 0. Olg.

Example 4

Manufacture of ceramic micro bearings

Alumina powder was used as the ceramic powder. A powder with an average particle size of 1 m was used. The composition of the molding composition used was a mixture of polystyrene, ethylene-vinyl acetate copolymer, polybutyl methacrylate, and 《Raffine wax in a ratio of 15: 15: 20: 50 as the organic filler. % + Organic binder 40 vol%.

The alumina powder and the organic binder were kneaded using a heat kneader at 150 ° C. for 1 hour, and the resulting kneaded product was formed into pellets having a length of 1 to 5 mm using a granulator. The obtained pellets were heated to 120 ° C. using an extrusion molding machine to produce a primary molded body. The mold used had an outer diameter of 1.2 mm, an inner diameter of 0.6 mm, and a height of 1.867 mm. The primary molded body obtained by the above extrusion molding is inserted into a press die (die size: outer diameter 1.3 mm, inner diameter 0.5 mm, height 1.4 mm), and heated and pressed under pressure. The next molded body was obtained. The molding conditions were a pressure of 700 kgf / cm ² and a mold temperature of 65 ° C. When the compact was cooled to 20 ° C, it was removed from the press die.

The obtained secondary compact was degreased at a maximum temperature of 400 ° C · air atmosphere, and the degreased compact was sintered at a maximum temperature of 1500 ° C and air atmosphere.

The obtained product (bearing) weight was 0.005 g.

Example 5

More M / 1 ヽ

A bearing shown in FIG. 2B was produced using the method according to the present invention.

In addition, urethane resin having an average particle diameter of 30 m was used as a thermosetting resin for increasing the porosity.

Stainless steel powder, organic binder and urethane resin are kneaded using a heat-kneader at 160 ° C for 1 hour, and the resulting kneaded product is pulverized using a non-mer mill and sieved to give a particle size of 50 to 100 μm A molding composition was prepared.

The molding composition obtained by sieving was molded at a pressure of 5000 kgf / cm ² using a pressure press machine to obtain a primary molded body. The mold used was an outer diameter of 1.2 mm, an inner diameter of 0.5 mm, and a height of 1.9 mm.

The primary compact obtained by the above press molding is inserted into a press die (die size: inner diameter 0.5 mm, outer diameter 1.3 mm, flange outer diameter 2. Omm, height 1.4 mm) and heated. Then, press molding was performed to obtain a secondary molded body. The molding conditions were a pressure of 800 kgf / cm ² and a mold temperature of 90 ° C. When the compact was cooled to 50 ° C, the press mold force was taken out. The obtained secondary compact was degreased at a maximum temperature of 500 ° C. · nitrogen atmosphere, and the degreased compact was sintered at a maximum temperature of 1250 ° C. under an argon atmosphere.

The product (bearing) weight obtained was O.Ollg.

[0037] In each example, 30 bearings were prepared, and the porosity and dimensional accuracy were calculated.

The porosity was calculated by the following formula.

Porosity = {1 (apparent density Z true density)} X 100

The apparent density was obtained by measuring with a helium gas substitution type density measuring device Accupick (manufactured by Shimadzu Corporation) in a state where the bearing surface was coated with wax to keep the pores inside.

The true density was determined by measuring with a helium gas substitution type density measuring device Accupick without coating the bearing with wax or the like.

[0038] "Comparative Example 1"

Stainless steel powder (SUS316L) was used as the metal powder. Stainless steel powder with an average particle size of 70 / zm was used. As an organic binder, 20 vol% of stearic acid was added. Stainless powder and stearic acid were dry mixed using a V blender.

Press molding was performed using the obtained pellet material. The force at which molding was performed at a molding pressure of 10,000 kgf / cm ^{2 The} molding material was not filled completely into the mold. For this reason, degreasing and sintering after molding were stopped.

[0039] "Comparative Example 2"

Alumina powder was used as the ceramic powder. Alumina powder with an average particle size of 1 μm was used.

A granular powder was prepared by adding 20 vol% stearic acid to the ceramic powder. The granulated granular powder had a particle size of 100 to 150 μm.

The obtained granular powder was used for press molding. The force at which molding was performed at a molding pressure of 10,000 kgf / cm ^{2 The} molding material was not filled completely into the mold. For this reason, degreasing and sintering after molding were stopped.

[0040] In the conventional powder press method, the applied amount of the organic binder is generally 20 vol% or less. However, in the manufacture of the micro bearing according to the present invention, the size of the mold is small. In comparison with Comparative Examples 1 and 2, it was found that the molding pressure was not sufficiently transmitted by this method and the molding material was not filled in the mold.

[0041] "Comparative Example 3"

The bearing shown in FIG. 2A was manufactured under exactly the same conditions as in Example 1 except that there was no “step of producing a primary molded body, inserting it into a heated press die, and applying pressure”.

[0042] Stainless steel powder (SUS316L) was used as the metal powder. A powder with an average particle size of 10 m was used.

As the organic binder, a mixture in which polystyrene, polybutylmethalylate, ethylene acetate butyl copolymer, and raffin wax were mixed at a ratio of 15: 15: 20: 50 was used.

The composition of the molding composition was 65 vol% stainless powder + 35 vol% organic binder. The powder and organic binder are kneaded using a heat kneader at 160 ° C for 1 hour, and the resulting kneaded product is pulverized using a hammer mill and sieved to form a composition with a particle size of 50 to L00 μm. I made a thing.

The molding composition obtained by sieving was molded at a pressure of 5000 kgf / cm ² using a pressure press machine to obtain a molded body. The mold used was an outer diameter of 1.3 mm, an inner diameter of 0.5 mm, and a height of 1.4 mm.

The obtained compact was degreased at a maximum temperature of 500 ° C · nitrogen atmosphere, and the degreased compact was sintered at a maximum temperature of 1100 ° C · argon atmosphere.

[0043] "Comparative Examples 4-6"

Similarly, the bearing shown in FIG. 2A was manufactured under exactly the same conditions as in Examples 2 to 4 except that there was no “step of producing a primary molded body, inserting it into a heated press die, and applying pressure”.

The comparative example corresponding to Example 2 is referred to as Comparative Example 4, and the comparative examples corresponding to Examples 3 and 4 are referred to as Comparative Examples 5 and 6 in the following order.

Similar to Comparative Example 3, in Comparative Examples 4 to 6, press molding, extrusion molding or injection using a mold for molding (mold size: outer diameter 1.3 mm, inner diameter 0.5 mm, height 1.4 mm) A molded body was produced in one step by molding, and the resulting molded body was degreased and sintered to produce a bearing. In each of Comparative Examples 3 to 6, create 30 bearings and calculate the porosity and dimensional accuracy. did.

Table 1 shows the results of Examples and Comparative Examples.

[table 1]

table 1

From the results of the above examples and comparative examples, the bearing manufactured using the method of the present invention has a dimensional accuracy that is an order of magnitude higher than that of a bearing manufactured by only one stage without performing hot press molding. It was revealed.

Claims

The scope of the claims

[1] A method of manufacturing a micro bearing having an outer diameter of 2 mm or less and an inner diameter of 1 mm or less,

A step of producing a molding composition containing metal powder having an average particle size of 1 to 150 m and an organic binder, wherein the content of the organic binder is 30 to 70 vol%,

Degreasing and sintering the secondary molded body to produce a sintered body,

A method for manufacturing an ultra-small porous bearing, comprising:

[2] A method of manufacturing a micro bearing having an outer diameter of 2 mm or less and an inner diameter of 1 mm or less,

A step of producing a molding composition comprising ceramic powder having an average particle size of 0.1 to 10 m and an organic binder, wherein the content of the organic binder is 30 to 70 vol%,

Degreasing and sintering the secondary molded body to produce a sintered body,

A method for manufacturing an ultra-small porous bearing, comprising:

[3] The method according to claim 1 or 2, wherein the molding composition contains 1 to 30 vol% of a thermosetting resin having an average particle size of 10 to 150 µm.

[4] An ultra-compact bearing made of metal or ceramics with a weight of 0.1 lg or less, an outer diameter of 2 mm or less, an inner diameter of 1 mm or less, and an inner diameter dimensional accuracy of ± 0.01 mm or less.

[5] Ultra-compact bearing made of metal or ceramics with a weight of 0.1 lg or less, an outer diameter of 1.5 mm or less, an inner diameter of 0.7 mm or less, and an inner diameter dimensional accuracy of ± 0.005 mm or less.

[6] The bearing according to claim 4 or 5, wherein the porosity is 15 vol% or more.

[7] A bearing having a flange, wherein the outer diameter of the flange is 2 mm or less! The bearing according to item 1. [8] The bearing according to any one of claims 4 to 7, wherein the bearing is an oil-impregnated bearing.