JP6461626B2

JP6461626B2 - Manufacturing method of sliding member

Info

Publication number: JP6461626B2
Application number: JP2015015663A
Authority: JP
Inventors: 尚樹八代; 大平　晃也; 晃也大平
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2015-01-29
Filing date: 2015-01-29
Publication date: 2019-01-30
Anticipated expiration: 2035-01-29
Also published as: JP2016141815A

Description

本発明は、すべり軸受等、少なくとも一部が相手部材と繰り返し摺動接触する摺動部材およびその製造方法に関し、特に、無数の内部気孔を有し、該内部気孔に潤滑油を含浸させた状態で使用される多孔質の摺動部材およびその製造方法に関する。 The present invention relates to a sliding member, such as a sliding bearing, in which at least a part is repeatedly slidably contacted with a mating member, and a method for manufacturing the same, and in particular, has a myriad of internal pores, and the internal pores are impregnated with lubricating oil. Relates to a porous sliding member used in the above and a method for manufacturing the same.

摺動部材の一種に、焼結金属の多孔質体からなるすべり軸受（焼結軸受）があり、このような焼結軸受は、通常、その内部気孔に潤滑油を含浸させた状態で使用される。この焼結軸受（焼結含油軸受）を、例えばラジアル荷重の支持用途に用いる場合、内周に挿入された軸との相対回転に伴って内部気孔に含浸させた潤滑油が軸との摺動部（摺動面）に滲み出す。そして、摺動部に滲み出した潤滑油が油膜を形成し、この油膜により軸がラジアル方向に相対回転自在に支持される。そのため、焼結軸受（焼結含油軸受）は、支持すべき軸を長期間に亘って精度良く支持することができる、という特徴を有する。 One type of sliding member is a sliding bearing (sintered bearing) made of a sintered metal porous body, and such a sintered bearing is usually used with its internal pores impregnated with lubricating oil. The When this sintered bearing (sintered oil-impregnated bearing) is used for supporting a radial load, for example, the lubricating oil impregnated in the internal pores with the relative rotation with the shaft inserted in the inner periphery slides with the shaft. It oozes out to the part (sliding surface). The lubricating oil that has oozed into the sliding portion forms an oil film, and the shaft is supported by the oil film so as to be relatively rotatable in the radial direction. Therefore, the sintered bearing (sintered oil-impregnated bearing) has a feature that the shaft to be supported can be accurately supported over a long period of time.

焼結軸受は、例えば、金属粉末を主原料とした原料粉末の圧粉体を得る圧縮成形工程、圧粉体を所定温度以上で加熱することにより金属粉末の粒子同士がネック結合した焼結体を得る焼結工程、焼結体の寸法矯正を行う寸法矯正工程、さらに、焼結体の内部気孔に潤滑油を含浸させる含油工程などを経ることで完成する。これら各種工程のうち、焼結工程では、圧粉体が鉄系粉末を主体としたものである場合、当該圧粉体を８００℃〜１３００℃程度の高温域で加熱するのが一般的であり、そのコストは焼結軸受の製造コスト全体の１／４〜１／２程度を占める。また、焼結工程では、圧粉体が加熱・冷却されるのに伴って膨張−収縮が生じるため、焼結工程で得られる焼結体に完成品として必要とされる寸法・形状精度を確保するには、焼結体にサイジング等の寸法矯正加工を施すことが必要不可欠となる。逆に言えば、上記のような高温域での熱処理を圧粉体に施さなくとも、すべり軸受に必要とされる強度を確保できれば、焼結工程およびその後の寸法矯正工程を省略することができ、すべり軸受の製造コストを大幅に低廉化できると考えられる。 Sintered bearings are, for example, a compression molding process for obtaining a green compact of raw material powder using metal powder as a main raw material, a sintered body in which metal powder particles are neck-bonded by heating the green compact at a predetermined temperature or higher. It is completed through a sintering process for obtaining a size, a dimension correcting process for correcting the dimension of the sintered body, and an oil impregnation process for impregnating the internal pores of the sintered body with lubricating oil. Of these various processes, in the sintering process, when the green compact is mainly composed of iron-based powder, the green compact is generally heated in a high temperature range of about 800 ° C to 1300 ° C. The cost occupies about 1/4 to 1/2 of the entire manufacturing cost of the sintered bearing. In the sintering process, expansion and contraction occur as the green compact is heated and cooled, ensuring the dimensional and shape accuracy required for the finished product in the sintered body obtained in the sintering process. In order to achieve this, it is indispensable to perform dimensional correction processing such as sizing on the sintered body. In other words, the sintering process and the subsequent dimensional correction process can be omitted if the strength required for the slide bearing can be secured without subjecting the green compact to the heat treatment in the high temperature region as described above. It is thought that the manufacturing cost of the slide bearing can be greatly reduced.

そこで、本発明者らは、例えば下記の特許文献１に開示されている水蒸気処理に着目した。すなわち、特許文献１には、鉄系粉末を主成分とする圧粉体に水蒸気処理を施すことにより粒子表面に酸化物皮膜（主に四酸化三鉄の皮膜）を形成し、この酸化物皮膜を介して粒子同士を結合することにより、鉄系部品を製造することが記載されている。 Then, the present inventors paid attention to, for example, the steam treatment disclosed in Patent Document 1 below. That is, Patent Document 1 discloses that an oxide film (mainly triiron tetroxide film) is formed on a particle surface by subjecting a green compact containing iron-based powder as a main component to water vapor treatment. It describes that an iron-based component is manufactured by bonding particles together through the.

特開昭６３−７２８０３号公報JP-A-63-72803

ところで、特許文献１に開示された発明の目的は、磁性材料の部品のように、あまり強度が要求されない部品を低コストに製造可能とすることにある（第２頁左上欄第６−１２行）。要するに、特許文献１に開示された技術手段の適用範囲は、特許文献１中に具体例として挙げられている軟磁性材料部品のように、高い強度を必要としない用途に限定される。そのため、すべり軸受をはじめとする摺動部材のように比較的高い強度を必要とする用途においては、特許文献１に開示された技術手段をそのまま採用しても、所望の機械的強度を具備した摺動部材を提供することができない。 By the way, the object of the invention disclosed in Patent Document 1 is to make it possible to manufacture a part that does not require much strength, such as a part made of a magnetic material, at low cost (page 2, left upper column, lines 6-12). ). In short, the scope of application of the technical means disclosed in Patent Document 1 is limited to applications that do not require high strength, such as soft magnetic material parts listed as specific examples in Patent Document 1. Therefore, in applications that require relatively high strength, such as sliding members such as plain bearings, even if the technical means disclosed in Patent Document 1 is adopted as it is, it has the desired mechanical strength. A sliding member cannot be provided.

また、摺動部材においては、相手部材との摺動部における摺動性（耐摩耗性）が良好であることも要求される。特に多孔質体からなる摺動部材では、内部気孔に保持した潤滑油の、相手部材との摺動部への滲み出し量が摺動性を左右することから、含油性（含油率）も良好であることが望まれる。しかしながら、特許文献１においては、含油率についても何ら検討されていない。 Further, the sliding member is also required to have good slidability (wear resistance) at the sliding portion with the counterpart member. Especially for sliding members made of a porous material, the amount of the lubricating oil retained in the internal pores exudes to the sliding portion with the mating member affects the slidability, so the oil content (oil content) is also good. It is desirable that However, Patent Document 1 does not discuss any oil content.

以上の実情に鑑み、本発明は、所望の機械的強度（圧環強さ）および含油率を兼ね備えた摺動部材を低コストに提供可能とすることを目的とする。 In view of the above circumstances, an object of the present invention is to make it possible to provide a sliding member having desired mechanical strength (compression strength) and oil content at low cost.

上記の目的を達成するため、本発明では、酸化物皮膜を形成可能な金属粉末を主原料とし、これに所定量の銅粉末を添加した原料粉末の圧粉体からなる摺動部材であって、圧粉体に水蒸気処理を施すことにより金属粉末の粒子間に形成された酸化物皮膜を有し、かつ、１５０ＭＰａ以上の圧環強さ、および１０ｖｏｌ％以上の含油率を有することを特徴とする摺動部材を提供する。 In order to achieve the above object, the present invention provides a sliding member comprising a green compact of a raw material powder in which a metal powder capable of forming an oxide film is a main raw material and a predetermined amount of copper powder is added thereto. , Characterized in that it has an oxide film formed between metal powder particles by subjecting the green compact to steam treatment, and has a crushing strength of 150 MPa or more and an oil content of 10 vol% or more. A sliding member is provided.

また、本発明では、１５０ＭＰａ以上の圧環強さ、および１０ｖｏｌ％以上の含油率を有する摺動部材を製造するための方法であって、酸化物皮膜を形成可能な金属粉末を主原料とし、これに所定量の銅粉末を添加した原料粉末の圧粉体を得る圧縮成形工程と、圧粉体を構成する金属粉末の粒子間に酸化物皮膜を形成させる水蒸気処理工程と、を含むことを特徴とする摺動部材の製造方法も併せて提供する。 Further, in the present invention, a method for producing a sliding member having a crushing strength of 150 MPa or more and an oil content of 10 vol% or more, the metal powder capable of forming an oxide film as a main raw material, A compression molding step of obtaining a green compact of a raw material powder in which a predetermined amount of copper powder is added to, and a water vapor treatment step of forming an oxide film between the metal powder particles constituting the green compact. A method for manufacturing the sliding member is also provided.

ここで、本発明でいう「酸化物皮膜を形成可能な金属粉末」とは、換言するならばイオン化傾向が大きい金属の粉末であり、例えば、鉄、アルミニウム、マグネシウム、クロム等の粉末、あるいは上記金属を含む合金粉末を採用できる。上記金属粉末は、一種のみ用いても良いし、複数種混合して用いても良い。また、「圧環強さ」は、ＪＩＳＺ２５０７：２０００中に規定された方法に基づいて得られる値であり、「含油率」は、ＪＩＳＺ２５０１：２０００中に規定された方法に基づいて得られる値である。 Here, the “metal powder capable of forming an oxide film” in the present invention is, in other words, a metal powder having a large ionization tendency, for example, a powder of iron, aluminum, magnesium, chromium or the like, or the above An alloy powder containing a metal can be employed. One kind of the metal powder may be used, or a plurality of kinds may be mixed and used. The “crushing strength” is a value obtained based on the method specified in JIS Z 2507: 2000, and the “oil content” is obtained based on the method specified in JIS Z 2501: 2000. Value.

水蒸気処理は、酸化雰囲気中で、酸化物皮膜を形成可能な金属粉末を含む原料粉末の圧粉体を所定温度（例えば４００〜７００℃の範囲内）に加熱された水蒸気と反応させることにより、上記金属粉末の粒子表面、ひいては粒子相互間に酸化物皮膜を形成する処理である。上記の金属粉末として鉄粉末を採用した場合、酸化物皮膜は主に四酸化三鉄（Ｆｅ_３Ｏ_４）および三酸化二鉄（Ｆｅ_２Ｏ_３）の皮膜である。そして、上記金属粉末の粒子間に形成される酸化物皮膜が粒子同士の結合媒体として機能し、圧粉体を焼結したときに形成されるネッキングの役割を代替すること、また、詳細な理由は不明であるものの、上記金属粉末に所定量の銅粉末を添加した原料粉末の圧粉体に水蒸気処理を施した場合、銅粉末を含まず、実質的に上記金属粉末のみからなる原料粉末の圧粉体に水蒸気処理を施した場合と比べると圧粉体が高強度化されること、などに由来して、未焼結の圧粉体を摺動部材として使用可能なレベル、具体的には１５０ＭＰａ以上の圧環強さを有する程度にまで高強度化することができる。また、金属粉末の粒子間に酸化物皮膜が形成されると圧粉体の気孔率が低下するが、本発明では、圧粉体が、水蒸気処理の実施によっても厚肉の酸化物皮膜が形成され難い銅粉末を含む関係上、水蒸気処理の実施に伴う気孔率、ひいては含油率の低下を抑制できると考えられる。そのため、１５０ＭＰａ以上の圧環強さと、１０ｖｏｌ％以上の含油率とを併せ持つ摺動部材を実現することができる。 Steam treatment is performed by reacting a green compact of a raw material powder containing a metal powder capable of forming an oxide film with steam heated to a predetermined temperature (for example, within a range of 400 to 700 ° C.) in an oxidizing atmosphere. This is a treatment for forming an oxide film between the particle surfaces of the metal powder and thus between the particles. When iron powder is employed as the metal powder, the oxide film is mainly a film of triiron tetroxide (Fe ₃ O ₄ ) and diiron trioxide (Fe ₂ O ₃ ). The oxide film formed between the particles of the metal powder functions as a bonding medium between the particles, and substitutes for the role of necking formed when the green compact is sintered. Although it is unclear, when steam treatment is performed on a green compact of a raw material powder obtained by adding a predetermined amount of copper powder to the metal powder, the raw material powder consisting essentially of only the metal powder does not contain copper powder. Compared to the case where the green compact is subjected to water vapor treatment, the green compact has a higher strength. Can be strengthened to such an extent that it has a crushing strength of 150 MPa or more. In addition, when an oxide film is formed between the metal powder particles, the porosity of the green compact decreases. However, in the present invention, the green compact forms a thick oxide film even when steam treatment is performed. In view of the copper powder that is difficult to be treated, it is considered that the decrease in the porosity and the oil content accompanying the implementation of the steam treatment can be suppressed. Therefore, a sliding member having both a crushing strength of 150 MPa or more and an oil content of 10 vol% or more can be realized.

また、圧粉体に施される水蒸気処理は、その処理温度が圧粉体を焼結する場合の加熱温度よりも格段に低く、処理後におけるワークの寸法変化量を小さくすることができるので、サイジング等の寸法矯正加工を省略することも可能となる。また、寸法変化量を小さくできれば、圧粉体の成形金型の設計が容易となる。さらに、処理温度が低ければ、処理時に必要なエネルギーも削減できて処理コストが減じられる。以上より、本発明によれば、所望の機械的強度および含油率を兼ね備えた摺動部材を低コストに提供することができる。 In addition, the steam treatment applied to the green compact is much lower than the heating temperature when the green compact is sintered, and the dimensional change of the workpiece after processing can be reduced. It becomes possible to omit dimension correction processing such as sizing. Further, if the amount of dimensional change can be reduced, the green compact molding die can be easily designed. Furthermore, if the processing temperature is low, the energy required for processing can be reduced and the processing cost can be reduced. As described above, according to the present invention, a sliding member having desired mechanical strength and oil content can be provided at low cost.

上述した特徴を有する摺動部材は、例えば、原料粉末として、上記金属粉末としての鉄粉末に対し、電解銅粉を５〜２０ｗｔ％（５ｗｔ％以上２０ｗｔ％以下）添加したもの、あるいは、上記金属粉末としての鉄粉末に対し、扁平銅粉を１．５〜２０ｗｔ％（１．５ｗｔ％以上２０ｗｔ％以下）添加したもの、などを使用することで得ることができる。 The sliding member having the above-described characteristics is, for example, a material powder in which 5 to 20 wt% (5 wt% or more and 20 wt% or less) of electrolytic copper powder is added to the iron powder as the metal powder, or the metal It can obtain by using what added 1.5-20 wt% (1.5 wt% or more and 20 wt% or less) of flat copper powder with respect to the iron powder as a powder.

本発明に係る摺動部材において、その母材となる圧粉体の圧粉密度が高すぎると、水蒸気処理時に圧粉体の芯部にまで水蒸気を侵入させることが難しく、圧粉体の強度向上に寄与する酸化物皮膜を圧粉体の芯部に形成することが難しくなるという懸念がある。一方、圧粉体の圧粉密度が低すぎると、圧粉体の取り扱い性が低下する、金属粉末の粒子間距離が拡大するため酸化物皮膜を所定態様で形成することが難しくなる、などといった懸念がある。従って、寸法測定法による圧粉体の圧粉密度は、５．０ｇ／ｃｍ^３〜７．６ｇ／ｃｍ^３の範囲内とするのが好ましい。 In the sliding member according to the present invention, if the green compact density of the green compact as the base material is too high, it is difficult for water vapor to penetrate into the core of the green compact during the steam treatment, and the strength of the green compact There is a concern that it is difficult to form an oxide film that contributes to improvement on the core of the green compact. On the other hand, if the green density of the green compact is too low, the handleability of the green compact will decrease, the distance between particles of the metal powder will increase, and it will be difficult to form an oxide film in a predetermined manner, etc. There are concerns. Thus, the green density of the compact due to dimensional measuring method ^is preferably in the range of ^{5.0g / cm 3 ~7.6g / cm 3} .

本発明は、すべり軸受の他、ギヤやカム等、他部材との摺動接触が繰り返される各種の摺動部材に適用することができる。 The present invention can be applied to various sliding members in which sliding contact with other members such as a gear and a cam is repeated in addition to a sliding bearing.

以上より、本発明によれば、所望の強度および含油率を兼ね備えた摺動部材を低コストに提供することができる。 As described above, according to the present invention, a sliding member having desired strength and oil content can be provided at low cost.

本発明の実施形態に係る摺動部材としてのすべり軸受の一例を示す断面図である。It is sectional drawing which shows an example of the slide bearing as a sliding member which concerns on embodiment of this invention. 上段は扁平銅粉の側面図、下段は同平面図である。The upper part is a side view of the flat copper powder, and the lower part is a plan view. 扁平銅粉を含む原料粉末の圧粉体の成形中における成形金型の部分拡大断面図である。It is a partial expanded sectional view of the shaping die in the process of shaping | molding of the green compact of the raw material powder containing flat copper powder. 評価試験の試験結果を示す図である。It is a figure which shows the test result of an evaluation test.

以下、本発明の実施の形態を図面に基づいて説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１に、本発明の一実施形態に係る摺動部材としてのすべり軸受１の一例を示す。このすべり軸受１は、円筒状の多孔質体からなり、内周に挿入した軸Ｓのラジアル荷重を支持するために使用される。すべり軸受１の内部気孔には、潤滑油が含浸されている。従って、例えば、軸Ｓが回転すると、これに伴って、すべり軸受１の内部気孔に含浸させた潤滑油がすべり軸受１の内周面２と軸Ｓの外周面との間（の軸受隙間）に滲み出して油膜を形成し、この油膜を介して軸Ｓがラジアル方向に回転自在に支持される。 FIG. 1 shows an example of a plain bearing 1 as a sliding member according to an embodiment of the present invention. The plain bearing 1 is made of a cylindrical porous body and is used to support the radial load of the shaft S inserted in the inner periphery. The internal pores of the slide bearing 1 are impregnated with lubricating oil. Therefore, for example, when the shaft S rotates, the lubricating oil impregnated in the internal pores of the slide bearing 1 is associated with the gap between the inner peripheral surface 2 of the slide bearing 1 and the outer peripheral surface of the shaft S. The oil is oozed out to form an oil film, and the shaft S is rotatably supported in the radial direction via the oil film.

すべり軸受１は、酸化物皮膜を形成可能な金属粉末（ここでは鉄粉末）を主原料とし、これに、所定量の銅粉末および固体潤滑剤を添加・混合した原料粉末の圧粉体からなる。圧粉体からなる（圧粉体を母材とした）すべり軸受１は、図１中の拡大図に模式的に示すように、Ｆｅ粒子３間に形成された酸化物皮膜５（より詳細には、各Ｆｅ粒子３の表面に形成され、隣接するＦｅ粒子３同士、さらにはＦｅ粒子３とＣｕ粒子４を結合した酸化物皮膜５）を有しており、すべり軸受１に必要とされる強度、具体的には１５０ＭＰａ以上の圧環強さを有する。また、このすべり軸受１は、軸Ｓとの摺動部（摺動面）における摺動性を良好なものとする（摺動部における摩耗を可及的に抑制し得るだけの潤滑油を内部気孔で保持可能とする）ために、１０ｖｏｌ％以上の含油率を有する。但し、圧粉体からなるすべり軸受１の含油率は、主に圧粉体の気孔率に左右される関係上、含油率が高過ぎるとすべり軸受１に必要とされる機械的特性を確保できない懸念がある。そのため、すべり軸受１の含油率は、１０〜３０ｖｏｌ％の範囲内とするのが好ましい。 The plain bearing 1 is made of a green powder of a raw material powder in which a metal powder (here, iron powder) capable of forming an oxide film is used as a main raw material, and a predetermined amount of copper powder and a solid lubricant are added to and mixed therewith. . As shown schematically in the enlarged view of FIG. 1, a sliding bearing 1 made of a green compact (using a green compact as a base material) has an oxide film 5 (more specifically) formed between Fe particles 3. Is formed on the surface of each Fe particle 3 and has an oxide film 5) in which adjacent Fe particles 3 are bonded together, and further Fe particles 3 and Cu particles 4 are combined, and is required for the sliding bearing 1. Strength, specifically, crushing strength of 150 MPa or more. In addition, this sliding bearing 1 has good slidability in the sliding portion (sliding surface) with the shaft S (with lubricating oil that can suppress wear in the sliding portion as much as possible. Therefore, it has an oil content of 10 vol% or more. However, the oil content of the slide bearing 1 made of the green compact is mainly influenced by the porosity of the green compact. Therefore, if the oil content is too high, the mechanical characteristics required for the slide bearing 1 cannot be secured. There are concerns. Therefore, the oil content of the slide bearing 1 is preferably in the range of 10 to 30 vol%.

上述の構成を有するすべり軸受１は、主に、圧縮成形工程、脱脂工程、水蒸気処理工程および含油工程を順に経て製造される。以下、上記の各工程について詳細に説明する。 The plain bearing 1 having the above-described configuration is mainly manufactured through a compression molding process, a degreasing process, a steam treatment process, and an oil impregnation process in order. Hereafter, each said process is demonstrated in detail.

［圧縮成形工程］
圧縮成形工程では、成形金型（成形装置装置）を用いて酸化物皮膜を形成可能な金属粉末を含む原料粉末を圧縮することにより、完成品形状（ここでは円筒状）の圧粉体を得る。圧粉体は、例えば一軸加圧成形法により成形することができるが、多軸ＣＮＣプレスによる成形、冷間等方圧加圧法、熱間等方圧加圧法等、公知のその他の成形法を採用しても構わない。なお、一軸加圧成形法であれば、その他の成形法に比べて圧粉体を低コストに得ることができるという利点がある。 [Compression molding process]
In the compression molding step, a green compact in the form of a finished product (here cylindrical) is obtained by compressing raw material powder containing metal powder capable of forming an oxide film using a molding die (molding apparatus). . The green compact can be formed by, for example, a uniaxial pressure forming method, but other known forming methods such as forming by a multi-axis CNC press, a cold isostatic pressing method, a hot isostatic pressing method and the like can be used. You may adopt. Note that the uniaxial pressure molding method has an advantage that a green compact can be obtained at a lower cost than other molding methods.

本実施形態では、原料粉末として、酸化物皮膜を形成可能な金属粉末としての鉄粉末を主原料とし、これに、所定量の銅粉末および固体潤滑剤を添加・混合した混合粉末を使用する。原料粉末に固体潤滑剤を含めることにより、粉末同士の摩擦、さらには粉末と金型間の摩擦を低減して圧粉体の成形性を高めることができる。固体潤滑剤としては、ステアリン酸亜鉛やステアリン酸カルシウム等の金属石けん系、アミドワックスや合成ポリエチレンワックス等のワックス系、二硫化モリブデンや二硫化タングステン等の硫化物系、黒鉛等のグラファイト系など、一般的に入手可能なものを適宜選択使用することができる。例示した固体潤滑剤は、一種のみを用いても良いし、二種以上を混合して用いても良い。なお、鉄粉末に対する固体潤滑剤の添加量が多過ぎると、すべり軸受１に必要とされる機械的特性を満足することが難しくなる。そのため、鉄粉末に対する固体潤滑剤の添加量は１．０ｗｔ％以下程度とする。 In the present embodiment, as a raw material powder, an iron powder as a metal powder capable of forming an oxide film is used as a main raw material, and a mixed powder obtained by adding and mixing a predetermined amount of copper powder and a solid lubricant is used. By including a solid lubricant in the raw material powder, it is possible to reduce the friction between the powders, and further reduce the friction between the powder and the mold, thereby enhancing the moldability of the green compact. Solid lubricants include metal soaps such as zinc stearate and calcium stearate, waxes such as amide wax and synthetic polyethylene wax, sulfides such as molybdenum disulfide and tungsten disulfide, and graphites such as graphite. Can be appropriately selected and used. The illustrated solid lubricant may be used alone or in combination of two or more. In addition, when there is too much addition amount of the solid lubricant with respect to iron powder, it will become difficult to satisfy the mechanical characteristics required for the slide bearing 1. Therefore, the addition amount of the solid lubricant with respect to the iron powder is set to about 1.0 wt% or less.

鉄粉末としては、例えば還元鉄粉やアトマイズ鉄粉を使用可能であり、本実施形態では、多孔質状（海面状）をなし、含油性や圧縮成形性に優れた還元鉄粉を使用する。また、銅粉末としては、電解銅粉やアトマイズ銅粉等を使用可能であり、本実施形態では、樹枝状をなし、圧縮成形性が良好な電解銅粉を使用する。鉄粉末に対する銅粉末（電解銅粉）の添加量が少なすぎると、所望の含油率を有するすべり軸受１を得ることができない懸念がある。その一方、鉄粉末に対する電解銅粉の添加量が多すぎると、鉄に比べて高価な銅の使用量が増してすべり軸受１のコスト高を招来することに加え、機械的特性を左右する鉄粉末の比率が相対的に低下する分、すべり軸受１の機械的特性が低下する懸念がある。そのため、還元鉄粉に対する電解銅粉の添加量は、５ｗｔ％以上２０ｗｔ％以下とする。 As the iron powder, for example, reduced iron powder or atomized iron powder can be used. In the present embodiment, reduced iron powder having a porous shape (sea surface shape) and excellent in oil impregnation property and compression moldability is used. Moreover, as copper powder, electrolytic copper powder, atomized copper powder, or the like can be used. In this embodiment, electrolytic copper powder having a dendritic shape and good compression moldability is used. When there is too little addition amount of the copper powder (electrolytic copper powder) with respect to iron powder, there exists a concern that the slide bearing 1 which has a desired oil content cannot be obtained. On the other hand, if the amount of electrolytic copper powder added to the iron powder is too large, the amount of expensive copper used increases compared to iron, leading to an increase in the cost of the slide bearing 1, and iron that affects the mechanical characteristics. There is a concern that the mechanical characteristics of the slide bearing 1 may be reduced due to the relative reduction of the powder ratio. Therefore, the addition amount of the electrolytic copper powder with respect to the reduced iron powder is 5 wt% or more and 20 wt% or less.

また、コストや圧縮成形性を考慮すると、還元鉄粉としては、その平均粒径が６０μｍ以上１２０μｍ以下のものを使用するのが好ましく、また電解銅粉としては、その平均粒径が１０μｍ以上５０μｍ以下のものを使用するのが好ましい。 In view of cost and compression moldability, it is preferable to use a reduced iron powder having an average particle size of 60 μm to 120 μm, and an electrolytic copper powder having an average particle size of 10 μm to 50 μm. The following are preferably used:

なお、成形圧等、圧粉体の成形条件は、寸法測定法による圧粉体の圧粉密度が５．０〜７．６ｇ／ｃｍ^３、好ましくは５．３〜７．２ｇ／ｃｍ^３以下、より好ましくは５．８〜７．０ｇ／ｃｍ^３となるように設定する。圧粉体の圧粉密度が上記の範囲内にあれば、所望の圧環強さおよび含油率（圧環強さ１５０ＭＰａ以上、含油率１０ｖｏｌ％以上）を兼ね備えたすべり軸受１を適切に得ることができる。 The compacting conditions such as compacting pressure are such that the compact density of the compact by a dimensional measurement method is 5.0 to 7.6 g / cm ³ , preferably 5.3 to 7.2 g / cm ³ or less. More preferably, it is set to be 5.8 to 7.0 g / cm ³ . If the green density of the green compact is within the above range, a sliding bearing 1 having a desired green crushing strength and oil content (crushing strength 150 MPa or more, oil content 10 vol% or more) can be obtained appropriately. .

［脱脂工程］
脱脂工程では、圧粉体を固体潤滑剤の融点以上で所定時間加熱することにより、固体潤滑剤（に含まれる潤滑成分）を分解・除去する。固体潤滑剤として例えばアミドワックスを用いた場合、圧粉体を３５０℃で９０分間加熱する。なお、この脱脂工程は必ずしも実施する必要はなく、必要に応じて実施すれば足りる。 [Degreasing process]
In the degreasing step, the green compact is heated for a predetermined time at a temperature equal to or higher than the melting point of the solid lubricant to decompose and remove the solid lubricant (the lubricating component contained therein). For example, when amide wax is used as the solid lubricant, the green compact is heated at 350 ° C. for 90 minutes. In addition, it is not necessary to implement this degreasing process, and it is sufficient if it implements as needed.

［水蒸気処理工程］
水蒸気処理工程では、酸化雰囲気中に置かれた圧粉体を４００〜７００℃の高温水蒸気と反応させる。これにより、圧粉体に含まれるＦｅ粒子３の表面には、酸化物皮膜５として、主に四酸化三鉄（Ｆｅ_３Ｏ_４）および三酸化二鉄（Ｆｅ_２Ｏ_３）の皮膜が徐々に形成され、この皮膜が成長するのに伴って、隣接する粒子同士が酸化物皮膜５を介して結合したすべり軸受１が得られる。水蒸気処理の処理時間は、圧粉体の圧粉密度、使用する金属粉末の種類（原料粉末の組成）、圧粉体の寸法等によって適宜調整されるが、すべり軸受１に必要とされる強度（圧環強さ１５０ＭＰａ以上）を確保し得るだけの時間（概ね２０分以上）とする。なお、水蒸気処理は、その処理時間を長くするほど圧粉体（すべり軸受１）の強度を高め得るというわけではなく、所定の処理時間を超えると、酸化物皮膜５の成長が停止して圧粉体の強度向上効果が飽和する。また、水蒸気処理の処理時間が長くなるほど、水蒸気処理に要するコストが増大する他、酸化物皮膜５が過剰に成長して圧粉体の気孔率が低下し、すべり軸受１に必要とされる含油率を確保できない懸念がある。従って、水蒸気処理の処理時間は、１０〜９０分程度とし、好ましくは２０〜４０分程度とする。 [Steam treatment process]
In the steam treatment step, the green compact placed in an oxidizing atmosphere is reacted with high-temperature steam at 400 to 700 ° C. Thereby, on the surface of the Fe particles 3 contained in the green compact, a film of mainly triiron tetroxide (Fe ₃ O ₄ ) and diiron trioxide (Fe ₂ O ₃ ) is gradually formed as the oxide film 5. As the film grows, the sliding bearing 1 in which adjacent particles are bonded via the oxide film 5 is obtained. The treatment time of the water vapor treatment is appropriately adjusted depending on the density of the green compact, the type of metal powder to be used (composition of raw material powder), the size of the green compact, etc., but the strength required for the slide bearing 1 The time (approximately 20 minutes or more) is sufficient to ensure the (crushing strength of 150 MPa or more). Note that the steam treatment does not mean that the strength of the green compact (slide bearing 1) can be increased as the treatment time is increased. If the treatment time exceeds a predetermined treatment time, the growth of the oxide film 5 stops and the pressure is increased. The effect of improving the strength of the powder is saturated. Further, as the treatment time for the steam treatment becomes longer, the cost required for the steam treatment increases, and the oxide film 5 grows excessively so that the porosity of the green compact decreases, and the oil impregnation required for the slide bearing 1 There is concern that the rate cannot be secured. Therefore, the treatment time for the steam treatment is about 10 to 90 minutes, preferably about 20 to 40 minutes.

［含油工程］
この含油工程では、いわゆる真空含浸等の手法により、隣接する粒子間に酸化物皮膜５が形成された圧粉体の内部気孔に潤滑油を含浸させる。なお、この含油工程は、必ずしも実施する必要はなく、圧粉体をいわゆる含油軸受として使用する場合にのみ実施すれば良い。 [Oil impregnation process]
In this oil impregnation step, lubricating oil is impregnated into the internal pores of the green compact in which the oxide film 5 is formed between adjacent particles by a technique such as so-called vacuum impregnation. Note that this oil impregnation step is not necessarily performed, and may be performed only when the green compact is used as a so-called oil impregnated bearing.

以上で説明したように、本実施形態に係るすべり軸受１は、圧粉体を母材とし、かつ圧粉体に水蒸気処理を施すことによりＦｅ粒子３相互間、さらにはＦｅ粒子３とＣｕ粒子４の間に形成された酸化物皮膜５を有する。そして、酸化物皮膜５が、圧粉体を構成する粒子同士の結合媒体として機能し、圧粉体を焼結したときに形成されるネッキングの役割を代替すること、また、詳細な理由は不明であるものの、鉄粉末に所定量の銅粉末を添加した原料粉末の圧粉体に水蒸気処理を施した場合、銅粉末を含まず、実質的に鉄粉末のみからなる原料粉末の圧粉体に水蒸気処理を施した場合と比べると圧粉体が高強度化されること、などに由来して、未焼結の圧粉体をすべり軸受１として使用可能なレベル、具体的には１５０ＭＰａ以上の圧環強さを有する程度にまで高強度化することができる。また、隣接する粒子間に酸化物皮膜５が形成されると圧粉体の気孔率が低下するが、本発明では、圧粉体が、水蒸気処理の実施によっても酸化物皮膜５が形成され難い銅粉末（Ｃｕ粒子４）を所定量含む関係上、水蒸気処理の実施に伴う気孔率、ひいては含油率の低下を抑制できると考えられる。そのため、１５０ＭＰａ以上の圧環強さと、１０ｖｏｌ％以上の含油率とを併せ持つすべり軸受１を実現することができる。 As described above, the sliding bearing 1 according to the present embodiment uses the green compact as a base material, and performs water vapor treatment on the green compact, so that the Fe particles 3 and the Fe particles 3 and the Cu particles are further treated. 4 has an oxide film 5 formed between them. The oxide film 5 functions as a bonding medium between particles constituting the green compact, and substitutes for the role of necking formed when the green compact is sintered, and the detailed reason is unknown. However, when the green powder of the raw material powder obtained by adding a predetermined amount of copper powder to the iron powder is subjected to the steam treatment, the green powder of the raw material powder which does not contain the copper powder and is substantially composed of only the iron powder. Derived from the fact that the green compact is strengthened compared to the case where the steam treatment is performed, and so on, the level at which unsintered green compact can be used as the slide bearing 1, specifically 150 MPa or more. The strength can be increased to such an extent that it has a crushing strength. In addition, when the oxide film 5 is formed between adjacent particles, the porosity of the green compact is reduced. However, in the present invention, the oxide film 5 is hardly formed even when the green compact is subjected to the steam treatment. In view of including a predetermined amount of copper powder (Cu particles 4), it is considered that the decrease in the porosity and the oil content due to the steam treatment can be suppressed. Therefore, the sliding bearing 1 having both the crushing strength of 150 MPa or more and the oil content of 10 vol% or more can be realized.

また、酸化物皮膜５を形成するために圧粉体に施される水蒸気処理は、その処理温度が、圧粉体を焼結する場合の加熱温度よりも格段に低いので、水蒸気処理の処理前後における圧粉体の寸法変化量を±０．１％以下程度にまで小さくすることができる。そのため、圧粉体を焼結した場合には、焼結工程後の実施が必要不可欠であったサイジング等の寸法矯正加工を省略することも可能になる。また、寸法変化量を小さくできれば、圧粉体を成形するための成形金型の設計が容易となる。さらに、処理温度が低ければ、処理時に必要なエネルギーも削減できるため、処理コストを低減できる。以上より、本発明によれば、所望の圧環強さおよび含油率を兼ね備えたすべり軸受１を低コストに得ることができる。 Also, the steam treatment applied to the green compact to form the oxide film 5 is much lower than the heating temperature when the green compact is sintered. The amount of dimensional change of the green compact can be reduced to about ± 0.1% or less. Therefore, when the green compact is sintered, it is possible to omit dimensional correction processing such as sizing, which was indispensable to be performed after the sintering process. Moreover, if the dimensional change amount can be reduced, it becomes easy to design a molding die for molding the green compact. Furthermore, if the processing temperature is low, the energy required for processing can be reduced, so that processing costs can be reduced. As described above, according to the present invention, the sliding bearing 1 having a desired crushing strength and oil content can be obtained at low cost.

以上、本発明の一実施形態に係る摺動部材としてのすべり軸受１およびその製造方法について説明したが、圧粉体（すべり軸受１）を得るための原料粉末に添加・混合する銅粉末としては、上述した電解銅粉以外にも、図２に示すような薄板状の扁平銅粉を採用することもできる。 As mentioned above, although the sliding bearing 1 as a sliding member which concerns on one Embodiment of this invention, and its manufacturing method were demonstrated, as copper powder added and mixed with the raw material powder for obtaining a compact (sliding bearing 1), Besides the above-described electrolytic copper powder, a thin plate-like flat copper powder as shown in FIG. 2 can also be employed.

扁平銅粉は、水アトマイズ粉等からなる原料銅粉を搗砕（Ｓｔａｍｐｉｎｇ）することで扁平化させたものである。図２に示すように、扁平銅粉としては、その粒子４’の長さＬが２０〜８０μｍで、厚さｔが０．５〜１．５μｍ（アスペクト比Ｌ／ｔ＝１３．３〜１６０）のものが主に用いられる。ここで言う「長さ」および「厚さ」は、扁平銅粉の各粒子４’の幾何学的な最大寸法を言う。扁平銅粉の見かけ密度は２．０ｇ／ｃｍ^３以下とする。 The flat copper powder is flattened by stamping raw material copper powder made of water atomized powder or the like. As shown in FIG. 2, as the flat copper powder, the length L of the particle 4 ′ is 20 to 80 μm and the thickness t is 0.5 to 1.5 μm (aspect ratio L / t = 13.3 to 160). ) Are mainly used. Here, “length” and “thickness” refer to the geometric maximum dimension of each particle 4 ′ of the flat copper powder. The apparent density of the flat copper powder is 2.0 g / cm ³ or less.

原料粉末に含める銅粉末として扁平銅粉を用いる場合、酸化物皮膜５を形成可能な金属粉末（例えば鉄粉末であり、特に還元鉄粉）に対する扁平銅粉の添加量は、１．５ｗｔ％以上２０ｗｔ％以下とする。 When flat copper powder is used as the copper powder included in the raw material powder, the addition amount of the flat copper powder to the metal powder (for example, iron powder, particularly reduced iron powder) capable of forming the oxide film 5 is 1.5 wt% or more. 20 wt% or less.

ここで、扁平銅粉の見かけ密度は鉄粉末（還元鉄粉）の見かけ密度よりも小さい。また、扁平銅粉の粒子４’は、図２に示したような薄板状で、かつ単位重量あたりの幅広面の面積が大きい。そのため、扁平銅粉を含む原料粉末を成形金型のキャビティに充填すると、扁平銅粉の粒子４’は、クーロン力等の影響を受けて成形金型の成形面に付着する。より詳細に述べると、扁平銅粉の粒子４’は、図３に示すように、その幅広面４ａ’を成形金型２０の成形面２１に向け、かつ層状に積み重なった状態で成形面２１の全域に付着する。その一方、扁平銅粉の粒子４’の層状組織よりも内側の領域（キャビティの中心側となる領域）では、還元鉄粉（の粒子３）、扁平銅粉（の粒子４’）、および固体潤滑剤６の分散状態が略均一化する。そして、キャビティに充填された原料粉末は、上記のような分布（分散）状態を維持したまま圧縮されるため、圧縮成形された圧粉体は、上記した各粉末の分布状態をほぼそのまま保持する。さらに、水蒸気処理の処理温度は銅の融点よりも格段に低く、水蒸気処理を実施しても銅粉末は溶融しないことから、水蒸気処理後の圧粉体（すべり軸受１）も、上記した各粉末の分布状態をほぼそのまま保持する。このため、扁平銅粉を含む圧粉体からなるすべり軸受１の表面（軸Ｓとの摺動面）は、鉄よりも銅が多く露出した銅リッチ面となる。従って、鉄粉末に添加・混合する銅粉末として扁平銅粉を選択した場合、電解銅粉を選択した場合と比較して、摺動特性が増強されたすべり軸受１を実現することができる。 Here, the apparent density of the flat copper powder is smaller than the apparent density of the iron powder (reduced iron powder). Further, the flat copper powder particles 4 ′ have a thin plate shape as shown in FIG. 2 and a large area on the wide surface per unit weight. Therefore, when the raw material powder containing flat copper powder is filled in the cavity of the molding die, the flat copper powder particles 4 ′ are affected by the Coulomb force or the like and adhere to the molding surface of the molding die. More specifically, as shown in FIG. 3, the flat copper powder particles 4 ′ are formed on the molding surface 21 with the wide surface 4 a ′ facing the molding surface 21 of the molding die 20 and stacked in layers. Adhere to the whole area. On the other hand, in the region inside the layered structure of the flat copper powder particles 4 ′ (region on the center side of the cavity), reduced iron powder (particles 3), flat copper powder (particles 4 ′), and solids The dispersed state of the lubricant 6 becomes substantially uniform. Since the raw material powder filled in the cavity is compressed while maintaining the distribution (dispersion) state as described above, the compression-molded green compact maintains the distribution state of each powder almost as it is. . Furthermore, since the treatment temperature of the water vapor treatment is much lower than the melting point of copper and the copper powder does not melt even if the water vapor treatment is performed, the green compact (slide bearing 1) after the water vapor treatment is also used for each of the powders described above. The distribution state of is kept almost as it is. For this reason, the surface (sliding surface with the axis | shaft S) of the sliding bearing 1 which consists of a green compact containing flat copper powder turns into a copper rich surface where copper exposed more than iron. Therefore, when the flat copper powder is selected as the copper powder to be added to and mixed with the iron powder, the sliding bearing 1 with enhanced sliding characteristics can be realized as compared with the case where the electrolytic copper powder is selected.

なお、成形金型２０の成形面２１への扁平銅粉の付着性を高めることにより、銅リッチの摺動面を有するすべり軸受１を得るため、扁平銅粉には、例えばステアリン酸等の流体潤滑剤を付着させても良い。流体潤滑剤は、原料粉末をキャビティに充填する前に扁平銅粉に付着させていれば良く、好ましくは扁平銅粉をその他の粉末と混合する前、より好ましくは原料銅粉を搗砕する段階で原料銅粉に付着させる。 In addition, in order to obtain the sliding bearing 1 which has a copper-rich sliding surface by improving the adhesiveness of the flat copper powder to the molding surface 21 of the molding die 20, for example, a fluid such as stearic acid is used as the flat copper powder. A lubricant may be attached. The fluid lubricant may be attached to the flat copper powder before filling the raw material powder into the cavity, preferably before the flat copper powder is mixed with other powders, more preferably the raw copper powder is ground. To attach to the raw material copper powder.

また、鉄粉末に添加・混合する銅粉末として扁平銅粉を選択した場合、鉄粉末に対する銅粉末の添加量を１．５ｗｔ％程度にまで少なくしても、１５０ＭＰａ以上の圧環強さと、１０ｖｏｌ％以上の含油率とを併せ持つすべり軸受１を実現することができる。そのため、鉄粉末に添加する銅粉末として電解銅粉を選択する場合と比較して、高価な銅の使用量を減じて一層の低コスト化を実現することもできる。 In addition, when flat copper powder is selected as the copper powder to be added to and mixed with the iron powder, even if the amount of copper powder added to the iron powder is reduced to about 1.5 wt%, the crushing strength of 150 MPa or more and 10 vol% A plain bearing 1 having both of the above oil contents can be realized. Therefore, compared with the case where electrolytic copper powder is selected as the copper powder to be added to the iron powder, the amount of expensive copper used can be reduced and further cost reduction can be realized.

なお、銅粉末として扁平銅粉を選択した場合に、鉄粉末に対する銅粉末の添加量を１．５ｗｔ％程度にまで減じても、すべり軸受１に必要とされる１５０ＭＰａ以上の圧環強さを確保できる理由の一つに、水蒸気処理に供される圧粉体が、図３に模式的に示したような各粉末の分布状態をほぼそのまま保持していることが挙げられる。すなわち、鉄粉末に対する銅粉末の添加量を同じにした二種類の原料粉末（鉄粉末に電解銅粉を添加したもの、および鉄粉末に扁平銅粉を添加したもの）で比較すると、電解銅粉を添加した原料粉末を用いた場合、キャビティの全域で電解銅粉が万遍なく分散している関係上、圧粉体の芯部ではＦｅ粒子同士の接触面積が相対的に小さくなるのに対し、扁平銅粉を添加した原料粉末を用いた場合、扁平銅粉の多くが成形金型２０の成形面２１に付着し（図３を参照）、圧粉体の芯部における扁平銅粉の分散量が相対的に少なくなる関係上、圧粉体の芯部ではＦｅ粒子同士の接触面積が相対的に大きくなる。そのため、扁平銅粉を含む圧粉体に水蒸気処理を施した場合、電解銅粉を含む圧粉体に水蒸気処理を施した場合に比べ、芯部における酸化物皮膜の形成量が多くなる。従って、鉄粉末に添加する銅粉末として扁平銅粉を選択した場合、鉄粉末に対する添加量を相対的に少なくしても、すべり軸受１に必要とされる圧環強さを確保できると考えられる。 In addition, when flat copper powder is selected as the copper powder, the crushing strength of 150 MPa or more required for the slide bearing 1 is secured even if the amount of copper powder added to the iron powder is reduced to about 1.5 wt%. One reason for this is that the green compact subjected to the steam treatment almost maintains the distribution state of each powder as schematically shown in FIG. That is, when compared with two types of raw material powders (the one in which electrolytic copper powder is added to iron powder and the one in which flat copper powder is added to iron powder) with the same amount of copper powder added to iron powder, electrolytic copper powder When the raw material powder to which the copper is added is used, the contact area between the Fe particles is relatively small in the core of the green compact because the electrolytic copper powder is uniformly dispersed throughout the cavity. When the raw material powder to which the flat copper powder is added is used, most of the flat copper powder adheres to the molding surface 21 of the molding die 20 (see FIG. 3), and the flat copper powder is dispersed in the core of the green compact. Due to the relatively small amount, the contact area between the Fe particles is relatively large at the core of the green compact. For this reason, when the green compact containing flat copper powder is subjected to water vapor treatment, the amount of oxide film formed in the core portion is increased compared to when the green compact containing electrolytic copper powder is subjected to water vapor treatment. Therefore, when flat copper powder is selected as the copper powder to be added to the iron powder, it is considered that the crushing strength required for the slide bearing 1 can be secured even if the amount added to the iron powder is relatively small.

以上では、ラジアル荷重のみを支持するすべり軸受１に本発明を適用した場合について説明を行ったが、本発明は、ラジアル荷重およびスラスト荷重の双方を支持するすべり軸受や、スラスト荷重のみを支持するすべり軸受にも好ましく適用することができる。 Although the case where the present invention is applied to the slide bearing 1 that supports only the radial load has been described above, the present invention supports the slide bearing that supports both the radial load and the thrust load or only the thrust load. It can be preferably applied to a slide bearing.

また、本発明は、すべり軸受のみならず、ギヤやカム等、相手部材と摺動する摺動面を有するその他の摺動部材に適用可能であるのはもちろんである。 Further, the present invention can be applied not only to a plain bearing but also to other sliding members having a sliding surface that slides with a mating member such as a gear and a cam.

本発明の有用性を実証するために、確認試験を実施した。この確認試験は、本発明の構成を具備する円筒状試験体（実施例１−７）および本発明の構成を具備しない円筒状試験体（比較例１−２）のそれぞれについて圧環強さおよび含油率を測定・算出し、求められた値に基づいて圧環強さおよび含油率のそれぞれを「◎」、「○」、「×」の三段階で評価すると共に、圧環強さおよび含油率の評価結果に基づいて総合的な良否を「○」又は「×」の何れかで判断するというものである。圧環強さおよび含油率の評価基準は以下のとおりとし、いずれか一方でも「×」の場合は総合評価を「×」とした。
［圧環強さ］
「◎」：１８０ＭＰａ以上
「○」：１５０ＭＰａ以上１８０ＭＰａ未満
「×」：１５０ＭＰａ未満
［含油率］
「◎」：１２ｖｏｌ％以上
「○」：１０ｖｏｌ％以上１２ｖｏｌ％未満
「×」：１０ｖｏｌ％未満
なお、圧環強さは、ＪＩＳＺ２５０７に準拠した方法で測定し（使用装置：島津製作所社製のオートグラフＡＧ−５０００Ａ）、含油率は、ＪＩＳＺ２５０１に準拠した方法で測定した値に基づいて算出した。含油率測定（算出）のために使用した潤滑油は、昭和シェル石油社製のシェルテラスＳ２Ｍ６８（油圧作動油／ＩＳＯ粘度ＶＧ６８相当）である。 In order to demonstrate the usefulness of the present invention, a confirmation test was conducted. In this confirmation test, the crushing strength and oil content of each of the cylindrical test body (Example 1-7) having the configuration of the present invention and the cylindrical test body (Comparative Example 1-2) not having the configuration of the present invention were confirmed. The crushing strength and oil content are evaluated in three stages of “◎”, “○”, and “×”, and the crushing strength and oil content are evaluated based on the measured values. Based on the result, the overall quality is judged by either “◯” or “×”. The evaluation criteria for the crushing strength and the oil content were as follows, and when either of them was “x”, the comprehensive evaluation was “x”.
[Crushing strength]
“◎”: 180 MPa or more “◯”: 150 MPa or more and less than 180 MPa “×”: less than 150 MPa [oil content]
“◎”: 12 vol% or more “◯”: 10 vol% or more and less than 12 vol% “×”: less than 10 vol% Note that the crushing strength was measured by a method according to JIS Z 2507 (applied device: manufactured by Shimadzu Corporation). Autograph AG-5000A), oil content was calculated based on the value measured by the method based on JIS Z 2501. The lubricating oil used for the oil content measurement (calculation) is Shell Terrace S2M68 (equivalent to hydraulic fluid / ISO viscosity VG68) manufactured by Showa Shell Sekiyu K.K.

次に、実施例１−７および比較例１−２に係る試験体は、原料粉末の組成を相互に異ならせた以外は、全て同一の手順・条件で作製した。具体的には、成形金型に充填した原料粉末を一軸加圧することにより、内径寸法：６ｍｍ、外径寸法：１２ｍｍ、高さ寸法：７ｍｍで、かつ圧粉密度６．２±０．１ｇ／ｃｍ^３の円筒状圧粉体を成形し、その後、この圧粉体に対して脱脂処理（処理条件：３５０℃×９０分）、さらには水蒸気処理（処理条件：５００℃×４０分）を施すことにより、上記の各試験体を得た。上記の各試験体を作製するために使用した原料粉末は以下のとおりである。なお、以下に示す銅粉末および固体潤滑剤（アミドワックス）の重量比は、鉄粉末（還元鉄粉）に対する添加量である。
実施例１：還元鉄粉−５ｗｔ％電解銅粉−０．７ｗｔ％アミドワックス
実施例２：還元鉄粉−１０ｗｔ％電解銅粉−０．７ｗｔ％アミドワックス
実施例３：還元鉄粉−２０ｗｔ％電解銅粉−０．７ｗｔ％アミドワックス
実施例４：還元鉄粉−１．５ｗｔ％扁平銅粉−０．７ｗｔ％アミドワックス
実施例５：還元鉄粉−５ｗｔ％扁平銅粉−０．７ｗｔ％アミドワックス
実施例６：還元鉄粉−１０ｗｔ％扁平銅粉−０．７ｗｔ％アミドワックス
実施例７：還元鉄粉−２０ｗｔ％扁平銅粉−０．７ｗｔ％アミドワックス
比較例１：還元鉄粉−０．７ｗｔ％アミドワックス
比較例２：還元鉄粉−１．５ｗｔ％電解銅粉−０．７ｗｔ％アミドワックス Next, the test bodies according to Example 1-7 and Comparative Example 1-2 were all manufactured under the same procedures and conditions except that the compositions of the raw material powders were different from each other. Specifically, by uniaxially pressing the raw material powder filled in the molding die, the inner diameter dimension: 6 mm, the outer diameter dimension: 12 mm, the height dimension: 7 mm, and the dust density 6.2 ± 0.1 g / A cylindrical green compact of ³ cm ³ is formed, and then subjected to degreasing treatment (treatment condition: 350 ° C. × 90 minutes) and further steam treatment (treatment condition: 500 ° C. × 40 minutes). As a result, the above test specimens were obtained. The raw material powder used for producing each of the above test bodies is as follows. In addition, the weight ratio of the copper powder and the solid lubricant (amide wax) shown below is an addition amount with respect to the iron powder (reduced iron powder).
Example 1: Reduced iron powder-5 wt% electrolytic copper powder-0.7 wt% amide wax Example 2: Reduced iron powder-10 wt% electrolytic copper powder-0.7 wt% amide wax Example 3: Reduced iron powder-20 wt% Electrolytic copper powder-0.7 wt% amide wax Example 4: Reduced iron powder-1.5 wt% flat copper powder-0.7 wt% amide wax Example 5: Reduced iron powder-5 wt% flat copper powder-0.7 wt% Amide wax Example 6: Reduced iron powder-10 wt% flat copper powder-0.7 wt% amide wax Example 7: Reduced iron powder-20 wt% flat copper powder-0.7 wt% amide wax Comparative Example 1: Reduced iron powder- 0.7 wt% amide wax Comparative Example 2: Reduced iron powder-1.5 wt% electrolytic copper powder-0.7 wt% amide wax

図４に基づき、各試験体の圧環強さおよび含油率について詳細に言及する。
比較例１は、含油率については１０ｖｏｌ％以上の合格基準を満足できたものの、圧環強さについては１５０ＭＰａ以上の合格基準を満足できなかった。また、比較例２は、圧環強さについては合格基準を満足できたものの、含油率が合格基準を満足できなかった。一方、還元鉄粉に対して５ｗｔ％以上の電解銅粉を添加した原料粉末を用いて作製した実施例１−３に係る試験体は、何れも、１５０ＭＰａ以上の圧環強さと、１２ｖｏｌ％以上の含油率とを有し、摺動部材に必要とされる圧環強さおよび含油率を高い水準で併せ持っている。また、還元鉄粉に対して１．５ｗｔ％以上の扁平銅粉を添加した原料粉末を用いて作製した実施例４−７に係る試験体は、何れも、１８０ＭＰａ以上の圧環強さと、１０ｖｏｌ％以上の含油率とを有し、摺動部材に必要とされる圧環強さおよび含油率を高い水準で併せ持っている。 Based on FIG. 4, the crushing strength and oil content of each specimen will be described in detail.
Although the comparative example 1 was able to satisfy the acceptance criteria of 10 vol% or more about oil content, it was not able to satisfy the acceptance criteria of 150 MPa or more about crushing strength. Moreover, although the comparative example 2 was able to satisfy the acceptance standard about the crushing strength, the oil content could not satisfy the acceptance standard. On the other hand, each of the test bodies according to Example 1-3 manufactured using the raw material powder to which 5 wt% or more of electrolytic copper powder is added to the reduced iron powder has a crushing strength of 150 MPa or more and 12 vol% or more. It has oil content and also has a high level of crushing strength and oil content required for the sliding member. Moreover, as for the test body which concerns on Example 4-7 produced using the raw material powder which added 1.5 wt% or more of flat copper powder with respect to reduced iron powder, all have a crushing strength of 180 MPa or more and 10 vol%. It has the above oil content, and has a high level of crushing strength and oil content required for the sliding member.

評価結果を総括すると、銅未添加の原料粉末（実質的に鉄粉末のみからなる原料粉末）の圧粉体に水蒸気処理を施してなる比較例１は、その圧環強さが１５０ＭＰａ未満であるのに対し、鉄粉末に所定量の銅粉末を添加した原料粉末の圧粉体に水蒸気処理を施してなる実施例１−７および比較例２は、何れも、圧環強さが１５０ＭＰａ以上の水準である。従って、水蒸気処理による圧粉体の高強度化には銅添加が有効であると言える。また、（水蒸気処理後の）圧粉体を、強度のみならず、高い含油率を併せ持つことが求められるすべり軸受（含油軸受）などの摺動部材として使用するには、鉄粉末に対し、５ｗｔ％以上の電解銅粉、あるいは１．５ｗｔ％以上の扁平銅粉を添加した原料粉末を使用することが有効であると言える。 When the evaluation results are summarized, Comparative Example 1 obtained by subjecting a green compact of raw material powder not containing copper (raw material powder consisting essentially of iron powder) to steam treatment has a crushing strength of less than 150 MPa. On the other hand, in Examples 1-7 and Comparative Example 2 in which the raw material powder compact obtained by adding a predetermined amount of copper powder to iron powder is subjected to the steam treatment, the crushing strength is at a level of 150 MPa or more. is there. Therefore, it can be said that the addition of copper is effective for increasing the strength of the green compact by steam treatment. Further, in order to use the green compact (after the steam treatment) as a sliding member such as a slide bearing (oil-impregnated bearing) that is required to have not only strength but also high oil content, It can be said that it is effective to use a raw material powder to which electrolytic copper powder of 1.5% or more or flat copper powder of 1.5 wt% or more is added.

１すべり軸受（摺動部材）
２内周面
３Ｆｅ粒子
４Ｃｕ粒子
４’ 扁平銅粉の粒子
４ａ‘ 幅広面
５酸化物皮膜
６固体潤滑剤
２０成形金型
２１成形面 1 Slide bearing (sliding member)
2 Inner peripheral surface 3 Fe particles 4 Cu particles 4 ′ Flat copper powder particles 4a ′ Wide surface 5 Oxide film 6 Solid lubricant 20 Mold 21 Mold surface

Claims

A method for producing a sliding member having a crushing strength of 150 MPa or more and an oil content of 10 vol% or more,
A compression molding process for obtaining a green compact of a raw material powder obtained by using a metal powder capable of forming an oxide film as a main raw material and adding a predetermined amount of copper powder thereto,
Wherein by applying a steam treatment to the green compact, wherein the water vapor treatment step you forming an oxide film between the particles of the metal powder constituting the green compact,
In the compression molding step, the raw material powder obtained by adding 5 to 20 wt% of electrolytic copper powder as the copper powder to the metal powder, or flat copper powder as the copper powder to the metal powder is 1.5%. Using the raw material powder added with ~ 20 wt%, the green compact having a green density measured by a dimension measurement method in the range of 5.0 to 7.6 g / cm ³ is obtained.
The manufacturing method of the sliding member, wherein the treatment time of the water vapor treatment in the water vapor treatment step is 20 to 40 minutes .

The method for manufacturing a sliding member according to claim 1, wherein the metal powder is iron powder.

The method for manufacturing a sliding member according to claim 1 or 2, wherein the steam treatment is a treatment of reacting the green compact placed in an oxidizing atmosphere with steam at 400 to 700 ° C.

The said raw material powder is a manufacturing method of the sliding member as described in any one of Claims 1-3 which contains the solid lubricant which made the addition amount with respect to the said metal powder 1.0 wt% or less.