JP5504863B2 - Mixed powder for powder metallurgy and sintered metal powder with excellent machinability - Google Patents
Mixed powder for powder metallurgy and sintered metal powder with excellent machinability Download PDFInfo
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本発明は、自動車焼結部品用などに好適な、金属粉末と合金用粉末と切削性改善用粉末と潤滑剤とを混合した粉末冶金用混合粉および該混合物を成形、焼結して得られる金属粉末製焼結体に係り、とくに、金属粉末製焼結体の切削性改善に関する。 The present invention is obtained by molding and sintering a powder mixture for powder metallurgy, which is a mixture of a metal powder, an alloy powder, a machinability improving powder, and a lubricant, which is suitable for automobile sintered parts and the like. The present invention relates to a metal powder sintered body, and more particularly to improvement of the machinability of a metal powder sintered body.
粉末冶金技術の進歩により、高寸法精度の複雑な形状の部品をニアネット形状に製造することができるようになり、粉末冶金技術を利用した製品が各種分野で利用されている。粉末冶金技術は、粉末を所望形状の金型に充填し、成形した後、焼結を行うことで形状の自由度が高いことが特徴となっている。そのため、形状が複雑な歯車等の機械部品に適用する事例が多い。 Advances in powder metallurgy technology have made it possible to manufacture parts with high dimensional accuracy and complex shapes in a near net shape, and products using powder metallurgy technology have been used in various fields. The powder metallurgy technique is characterized by a high degree of freedom in shape by filling powder in a mold having a desired shape, forming, and then sintering. For this reason, there are many cases of application to mechanical parts such as gears having complicated shapes.
例えば、鉄系粉末冶金の分野では、鉄基粉末（金属粉末）に、銅粉、黒鉛粉などの合金用粉末と、ステアリン酸亜鉛、ステアリン酸リチウム等の潤滑剤とを混合した鉄基混合粉を、所定形状の金型に充填したのち加圧成形して成形体とし、ついで、焼結処理を施して焼結部品を得ている。このようにして得られた焼結部品は、一般的に寸法精度が良いとされるが、非常に厳しい寸法精度が要求される焼結部品を製造する場合には、焼結した後に、さらに切削加工を施す必要がある。 For example, in the field of iron-based powder metallurgy, iron-based mixed powder in which iron-based powder (metal powder) is mixed with alloy powder such as copper powder and graphite powder and lubricant such as zinc stearate and lithium stearate. Are filled into a mold having a predetermined shape and then pressure-molded to form a molded body, and then subjected to a sintering treatment to obtain a sintered part. The sintered parts obtained in this way are generally considered to have good dimensional accuracy. However, when manufacturing sintered parts that require extremely strict dimensional accuracy, the sintered parts are further cut after sintering. Need to be processed.
しかし、このようにして製造された焼結体は、空孔の含有比率が高く、溶解法による金属材料にくらべて、切削抵抗が高い。このため、従来から、焼結体の切削性を向上させる目的で、鉄基混合粉に、Pb、Se、Te等を、粉末で添加、あるいは鉄粉あるいは鉄基粉末に合金化して添加することが行なわれてきた。 However, the sintered body produced in this way has a high content ratio of pores, and has a higher cutting resistance than a metal material obtained by the melting method. For this reason, for the purpose of improving the machinability of the sintered body, conventionally, Pb, Se, Te, etc. are added to the iron-based mixed powder as a powder, or alloyed with iron powder or iron-based powder. Has been done.
しかし、Pbは融点が330℃と低いため、焼結過程で溶融し、しかも鉄中に固溶せず基地中に均一分散させることが難しいという問題があった。また、Se、Teは、焼結体を脆化させるため、焼結体の機械的特性の劣化が著しいという問題があった。これらの粉末以外にも、切削性改善のために種々の粉末を添加することが提案されている。 However, since Pb has a melting point as low as 330 ° C., it has a problem that it is melted during the sintering process and is not dissolved in iron and is difficult to uniformly disperse in the matrix. Moreover, since Se and Te embrittle the sintered body, there was a problem that the mechanical properties of the sintered body deteriorated remarkably. In addition to these powders, it has been proposed to add various powders to improve machinability.
またさらに、空孔は、熱伝導性が悪いため、加工時の摩擦発熱が蓄積され、工具の表面温度が上がりやすいため、切削工具が著しく損耗し、その結果、切削加工費が増大し、焼結部品の製造コストの上昇を招くという問題がある。 Furthermore, since the pores have poor thermal conductivity, frictional heat generated during machining is accumulated, and the surface temperature of the tool is likely to rise, so that the cutting tool is significantly worn, resulting in increased cutting costs and firing. There is a problem that the manufacturing cost of the connecting parts is increased.
このような問題に対し、例えば、特許文献１には、鉄粉に、10μm以下の非常に微細な硫化マンガン粉末を重量％で0.05〜５％混合した焼結物体製造用鉄粉混合物が記載されている。特許文献１に記載された技術によれば、大きな寸法変化及び強度劣化を伴うことなく、焼結材の被削性（切削性）を改善できるとしている。 For such a problem, for example, Patent Document 1 describes an iron powder mixture for manufacturing a sintered body in which 0.05 to 5% by weight of a very fine manganese sulfide powder of 10 μm or less is mixed with iron powder. ing. According to the technique described in Patent Document 1, the machinability (cutability) of the sintered material can be improved without being accompanied by a large dimensional change and strength deterioration.
また、特許文献２には、鉄粉を主体とし、アノールサイト相および／またはゲーレナイト相を有する平均粒径50μm以下のCaO−Al２O３−Si２O系複合酸化物の粉末を0.02〜0.3重量％含有する粉末冶金用鉄系混合粉末が記載されている。特許文献２に記載された技術によれば、切削時に加工面に露出した複合酸化物粉末が工具表面に付着して工具保護膜（いわゆるベラーク層）を形成し、工具の材質劣化を防止して切削性を改善することができるとしている。 Patent Document 2 discloses a powder of a CaO—Al 2 O 3 —Si 2 O-based composite oxide having an average particle size of 50 μm or less, mainly composed of iron powder and having an anolite phase and / or gehlenite phase, of 0.02 to 0.3. An iron-based mixed powder for powder metallurgy containing by weight is described. According to the technique described in Patent Document 2, the complex oxide powder exposed on the machined surface during cutting adheres to the tool surface to form a tool protection film (so-called Berak layer), thereby preventing deterioration of the tool material. It is said that the machinability can be improved.
また、特許文献３には、鉄基粉末と、合金用粉末と、切削性改善用粉末として硫化マンガン粉とリン酸カルシウム粉および／またはヒドロキシアパタイト粉とを、さらに潤滑剤を混合してなる鉄基混合粉が記載されている。ここで、硫化マンガンは切屑の微細化に有効に作用し、一方、リン酸カルシウム粉およびヒドロキシアパタイト粉は、切削時に工具の表面に付着して工具保護膜を形成して、工具表面の変質を防止又は抑制するとしている。特許文献３に記載された技術によれば、焼結体の機械的特性の劣化を伴うこともなく、切削性を向上できるとしている。 Patent Document 3 discloses an iron-based powder comprising an iron-based powder, an alloy powder, manganese sulfide powder, calcium phosphate powder and / or hydroxyapatite powder as a machinability improving powder, and further mixed with a lubricant. The powder is described. Here, manganese sulfide works effectively for finer chips, while calcium phosphate powder and hydroxyapatite powder adhere to the surface of the tool during cutting to form a tool protection film to prevent tool surface alteration or Trying to suppress. According to the technique described in Patent Document 3, it is said that the machinability can be improved without deteriorating the mechanical properties of the sintered body.
しかしながら、特許文献１、３に記載された技術では、硫化マンガン（MnS）粉を含むため、Sが焼結中に揮発し、焼結炉内の汚染や、焼結体外観の悪化の原因となるとともに、さらに、焼結体中に残留したS、あるいはMnSは、発錆を促進し、焼結部品の耐食性を低下させるという問題がある。また、特許文献２に記載された技術では、粉体特性、焼結体特性の低下を防止するために、複合酸化物粉末を不純物が少なく、かつ粒度を調整した粉末とする必要があり、材料コストが高騰するという問題があった。 However, in the techniques described in Patent Documents 1 and 3, since manganese sulfide (MnS) powder is included, S volatilizes during sintering, causing contamination in the sintering furnace and deterioration of the appearance of the sintered body. Further, S or MnS remaining in the sintered body has a problem that it promotes rusting and lowers the corrosion resistance of the sintered part. In addition, in the technique described in Patent Document 2, in order to prevent deterioration of powder characteristics and sintered body characteristics, the composite oxide powder needs to be a powder with less impurities and an adjusted particle size. There was a problem that the cost increased.
さらに、特許文献２、３に記載されたベラーク形成による切削性改善は、旋削加工では切削動力低減に有効であるが、切屑が微細化しないため、ドリル切削においては、切り屑の排除性が悪く、ドリル切削性には問題を残している。 Further, the improvement in machinability by forming a veraque described in Patent Documents 2 and 3 is effective in reducing cutting power in turning, but the chip is not miniaturized, and therefore, in drill cutting, the chip eliminability is poor. There remains a problem with drill machinability.
本発明は、上記した従来技術の問題を有利に解決し、焼結炉の炉内環境に悪影響を及ぼすことなく、成形体の焼結ができ、さらに、優れた切削性、詳しくは、優れた旋盤切削性（以下、旋削性ともいう）および優れたドリル切削性を兼備した焼結体を得ることが可能な、粉末冶金用混合粉を提供することを目的とする。また、本発明では、優れた旋削性およびドリル加工性を兼備し、切削性に優れた焼結体を提供することを目的とする。 The present invention advantageously solves the above-mentioned problems of the prior art, enables the compact to be sintered without adversely affecting the furnace environment of the sintering furnace, and has excellent machinability, in particular, excellent An object of the present invention is to provide a powder mixture for powder metallurgy capable of obtaining a sintered body having both lathe machinability (hereinafter, also referred to as lathe machinability) and excellent drill machinability. Another object of the present invention is to provide a sintered body having excellent turning properties and drilling properties and having excellent machinability.
本発明者らは、上記した目的を達成するために、焼結体の切削性に及ぼす各種要因、とくに添加材の影響について鋭意考究した。その結果、混合粉中に、金属粉末、合金用粉末、潤滑剤とともに加える切削性改善用粉末（添加材）として、焼結体基地相よりも硬さが低い軟質金属化合物粉末と、焼結体基地相よりも硬さが高い硬質金属化合物粉末とを併せて混合し、基地相中に、基地相よりも軟らかい軟質金属化合物粒子と、基地相より硬い硬質金属化合物粒子とを分散させることにより、旋盤での切削性（旋削性）とドリルによる切削性（ドリル切削性）とを共に向上でき、焼結体の切削性改善に有効であることに想到した。さらに、これにより、成形時には、圧粉密度の低下や、抜出力の増大を招くことなく成形でき、焼結時には、焼結炉の炉内環境に悪影響を及ぼすこともなく焼結でき、しかも得られる焼結体を、切削性に優れた焼結体とすることができることを見出した。なお、硬質金属化合物粉末としては、金属ホウ化物が優れていることも知見した。 In order to achieve the above-mentioned object, the present inventors diligently studied various factors on the machinability of the sintered body, particularly the influence of additives. As a result, a soft metal compound powder having a hardness lower than that of the sintered body base phase as a machinability improving powder (additive) added to the mixed powder together with the metal powder, the alloy powder, and the lubricant, and the sintered body By mixing together the hard metal compound powder having a hardness higher than the base phase, and dispersing the soft metal compound particles softer than the base phase and the hard metal compound particles harder than the base phase in the base phase, It was conceived that both lathe machinability (turnability) and drill machinability (drill machinability) can be improved, which is effective in improving the machinability of the sintered body. Furthermore, this enables molding without reducing the green density and increasing the extraction force during molding, and enables sintering without adversely affecting the in-furnace environment of the sintering furnace. It was found that the obtained sintered body can be a sintered body excellent in machinability. In addition, as a hard metal compound powder, it also discovered that a metal boride was excellent.
切削性改善用粉末として、軟質金属化合物粉末（軟質材粉末ともいう）と、硬質金属化合物粉末（硬質材粉末ともいう）とを併せて混合することにより、旋盤での切削性（旋削性）とドリルによる切削性（ドリル切削性）とを共に向上できる。このような焼結体の切削性改善の機構について、現在までのところ明確になっているわけではないが、本発明者らは次のように考えている。 As a powder for improving machinability, a soft metal compound powder (also referred to as soft material powder) and a hard metal compound powder (also referred to as hard material powder) are mixed together to obtain a machinability (turnability) on a lathe. Both cutting performance (drill cutting performance) by a drill can be improved. The mechanism for improving the machinability of such a sintered body has not been clarified so far, but the present inventors consider as follows.
一般に、旋盤切削などの切削加工に際して、工具の先端には、塑性変形および剪断変形を起こす被削材の抗力が作用する。そして、工具の表面には被削材との摩擦力が作用し、工具表面の摩耗が生じる。また、工具内部には、抗力（切削抵抗）が作用し、変形あるいは亀裂発生の原因となり、工具が劣化してゆく。一方、焼結体内部に、焼結体基地相よりも軟質の、軟質金属化合物粒子（軟質材粒子）が分散している場合には、軟質金属化合物粒子（軟質材粒子）が、基地相の変形よりも低い応力で変形するため、工具に作用する抗力が低下し、工具の摩耗、変形あるいは亀裂の発生を抑制し、工具寿命が改善される。 In general, in cutting such as lathe cutting, a drag force of a work material that causes plastic deformation and shear deformation acts on the tip of a tool. Then, frictional force with the work material acts on the surface of the tool, and wear of the tool surface occurs. Also, drag (cutting resistance) acts inside the tool, causing deformation or cracking, and the tool deteriorates. On the other hand, when soft metal compound particles (soft material particles) that are softer than the sintered matrix base phase are dispersed inside the sintered body, the soft metal compound particles (soft material particles) Since the deformation is performed with a lower stress than the deformation, the drag acting on the tool is reduced, the wear, deformation or cracking of the tool is suppressed, and the tool life is improved.
一方、ドリル切削加工においては、上記したような機構で、工具に作用する抗力が低下するだけでは、工具の寿命改善は生じない。というのは、ドリル切削時に発生した切屑が排除されずに穿孔中に存在する場合があり、これがドリルと被削材の間に噛みこみ、結果的に工具に加わる応力が増大して、工具摩耗や工具破損の原因となる。また、ドリル貫通の際には、穿孔表面に切屑が付着し、いわゆる“バリ”が発生する。バリの発生は、部品の加工精度を低下させるうえ、バリ除去の加工工程が必要となり、部品製造のコストを高騰させる。 On the other hand, in drill cutting, the life of the tool is not improved only by reducing the drag acting on the tool with the mechanism as described above. This is because chips generated during drilling may be present during drilling instead of being eliminated, and this may be caught between the drill and the work material, resulting in increased tool stress and tool wear. Or cause damage to the tool. Further, when drilling, chips adhere to the drilling surface, and so-called “burrs” are generated. The generation of burrs reduces the processing accuracy of the parts and requires a burrs removal processing step, which increases the cost of manufacturing the parts.
本発明では、焼結体の基地相中に、軟質金属化合物粒子（軟質材粒子）に加えて、焼結体基地相よりも硬質の硬質金属化合物粒子（硬質材粒子）を分散させるため、切屑発生時に硬質金属化合物粒子（硬質材粒子）に応力が集中し、切屑内部での亀裂の発生を促進する。このため、切屑が微細化し、ドリル穿孔の際の切屑排出性が向上し、ドリルに作用する抗力が低下して、ドリル寿命を改善できる。さらには、切屑が排除されやすくなるため、バリの発生を抑制するという副次的効果をももたらす。 In the present invention, in order to disperse hard metal compound particles (hard material particles) harder than the sintered base phase in addition to the soft metal compound particles (soft material particles) in the matrix phase of the sintered body, At the time of occurrence, stress concentrates on the hard metal compound particles (hard material particles), and promotes the generation of cracks inside the chips. For this reason, the chips become finer, the chip discharging performance during drilling is improved, the drag acting on the drill is lowered, and the drill life can be improved. Furthermore, since chips are easily removed, a secondary effect of suppressing the generation of burrs is also brought about.
基地相中に、軟質金属化合物（軟質材）粒子および硬質金属化合物（硬質材）粒子を分散させた焼結体とする本発明によれば、上記したような機構によって、優れた旋削性および優れたドリル切削性をともに確保できたものと考えている。 According to the present invention, which is a sintered body in which soft metal compound (soft material) particles and hard metal compound (hard material) particles are dispersed in the matrix phase, excellent turning properties and excellent by the mechanism as described above. It is thought that both drill cutting performance was secured.
本発明は、かかる知見に基づき、さらに検討を加えて完成されたものである。すなわち本発明の要旨は次のとおりである。 The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
（１）金属粉末と、合金用粉末と、さらに切削性改善用粉末と、潤滑剤粉末とを混合してなる粉末冶金用混合粉であって、前記金属粉末が、鉄基粉末であり、前記切削性改善用粉末が、軟質金属化合物粉末と、硬質金属化合物粉末とからなり、該軟質金属化合物粉末が、タルク粉末、エンスタタイト粉末、カオリン粉末、マイカ粉末、粘土粉末、蛍石粉末、水砕スラグ粉末のうちから選ばれた１種または２種以上で、該硬質金属化合物粉末が、金属ホウ化物粉末であることを特徴とする粉末冶金用混合粉。 (1) A mixed powder for powder metallurgy obtained by mixing a metal powder, an alloy powder, a machinability improving powder, and a lubricant powder, wherein the metal powder is an iron-based powder, machinability improving powder comprises a soft metal compound powder, Ri Do and a hard metal compound powder, soft quality metal compound powder, talc powder, enstatite powders, kaolin powder, mica powder, clay powder, fluorite powder, water grinding one member selected from among slag powder or two or more, the rigid metal compound powder is a powder metallurgical mixed powder, wherein the metal boride powder der Rukoto.
（２）（１）において、前記硬質金属化合物粉末の配合量が、前記金属粉末、前記合金用粉末および前記切削性改善用粉末の合計量に対する質量％で、0.01〜0.5％であり、前記軟質金属化合物粉末の配合量が、前記金属粉末、前記合金用粉末および前記切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％であることを特徴とする粉末冶金用混合粉。 (2) In (1), the amount of the hard metal compound powder is 0.01% to 0.5% by mass% with respect to the total amount of the metal powder, the alloy powder and the machinability improving powder, and the soft A mixed powder for powder metallurgy, characterized in that the compounding amount of the metal compound powder is 0.01 to 1.0% by mass% based on the total amount of the metal powder, the alloy powder and the machinability improving powder.
（３）（１）または（２）において、前記金属ホウ化物粉末が、TiB２粉末、ZrB２粉末、NbB２粉末のうちから選ばれた１種または２種以上であることを特徴とする粉末冶金用混合粉。 ( 3 ) The powder according to ( 1) or (2 ), wherein the metal boride powder is one or more selected from TiB 2 powder, ZrB 2 powder, and NbB 2 powder. Mixed powder for metallurgy.
（４）粉末冶金用混合粉を、成形、焼結してなる焼結体であって、
前記粉末冶金用混合粉が、金属粉末と、合金用粉末と、さらに軟質金属化合物粉末と硬質金属化合物粉末とからなる切削性改善用粉末と、潤滑剤粉末とを混合してなる粉末冶金用混合粉であり、前記金属粉末を鉄基粉末とし、前記焼結体の基地相中に、該基地相の平均硬さより低い硬さの軟質金属化合物の粒子と、前記基地相の平均硬さより高い硬さの硬質金属化合物の粒子とが分散してなり、前記軟質金属化合物が、タルク、エンスタタイト、カオリン、マイカ、粘土、蛍石、水砕スラグのうちから選ばれた１種または２種以上からなり、前記硬質金属化合物粉末が金属ホウ化物（但し、Cr、Fe、Ｃ、Ｂとが反応して形成された硬質の複合炭、硼化物である場合を除く）であることを特徴とする優れた切削性を有する金属粉末製焼結体。
( 4 ) A sintered body obtained by molding and sintering mixed powder for powder metallurgy,
The powder metal blend powder, a metal powder, an alloy powder, further the machinability improvement powder comprising a soft metal compound powder and the hard quality metal compound powder, powder metallurgy obtained by mixing the lubricant powder It is a mixed powder, the metal powder is an iron-based powder, and in the matrix phase of the sintered body, particles of a soft metal compound having a hardness lower than the average hardness of the matrix phase and higher than the average hardness of the matrix phase Ri Na dispersed particles of hardness of the hard metal compound, wherein the soft metal compound, talc, enstatite, kaolin, mica, clay, fluorite, one or two selected from among the granulated slag made above, the hard metal compound powder is a metal boride (however, Cr, Fe, C, complex carbonitride rigid and is formed by the reaction B, except when a boride), wherein der Rukoto Metal powder sintered body having excellent machinability.
（５）（４）において、質量％で、前記硬質金属化合物の粒子の含有量が、0.01〜0.5％であり、前記軟質金属化合物の粒子の含有量が、0.01〜1.0％であることを特徴とする金属粉末製焼結体。 ( 5 ) In ( 4 ), the content of particles of the hard metal compound is 0.01 to 0.5% by mass%, and the content of particles of the soft metal compound is 0.01 to 1.0%. A sintered body made of metal powder.
（６）（４）または（５）において、前記金属ホウ化物が、TiB２、ZrB２、NbB２のうちから選ばれた１種または２種以上であることを特徴とする金属粉末製焼結体。 ( 6 ) The sintered metal powder according to ( 4) or (5 ), wherein the metal boride is one or more selected from TiB 2 , ZrB 2 , and NbB 2 body.
（７）金属粉末と、合金用粉末と、切削性改善用粉末と、さらに潤滑剤粉末とを配合し、混合して混合粉とする混合粉の製造方法であって、前記切削性改善用粉末を、軟質金属化合物粉末と硬質金属化合物粉末とからなる粉末とし、前記混合が、前記金属粉末と前記合金用粉末に、一次混合材として前記切削性改善用粉末の一部または全部と、さらに前記潤滑剤粉末の一部を添加し、前記潤滑剤の融点のうちの最低値以上に加熱し、少なくとも１種の潤滑剤を溶融させて、混合したのち、所定の温度以下に冷却して固化させる一次混合と、さらに前記切削性改善用粉末の残部および／または前記潤滑剤の残部を二次混合材として添加し、混合する二次混合とからなる工程であることを特徴とする粉末冶金用混合粉の製造方法。 ( 7 ) A method for producing a mixed powder obtained by blending a metal powder, an alloy powder, a machinability improving powder, and a lubricant powder and mixing them to form a mixed powder, the machinability improving powder. Is a powder comprising a soft metal compound powder and a hard metal compound powder, and the mixing is performed on the metal powder and the alloy powder, a part or all of the machinability improving powder as a primary mixture, and the A part of the lubricant powder is added, heated to the minimum value of the melting point of the lubricant, and at least one lubricant is melted and mixed, and then cooled to a predetermined temperature or lower and solidified. Powder metallurgy mixing characterized in that it is a process comprising primary mixing and further secondary mixing in which the remainder of the machinability improving powder and / or the remainder of the lubricant is added and mixed as a secondary mixture. Powder manufacturing method.
（８）（７）において、前記硬質金属化合物粉末の配合量が、前記金属粉末、前記合金用粉末および前記切削性改善用粉末の合計量に対する質量％で、0.01〜0.5％であり、前記軟質金属化合物粉末の配合量が、前記金属粉末、前記合金用粉末および前記切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％であることを特徴とする粉末冶金用混合粉の製造方法。 ( 8 ) In ( 7 ), the amount of the hard metal compound powder is 0.01% to 0.5% by mass% based on the total amount of the metal powder, the alloy powder, and the machinability improving powder, A method for producing a mixed powder for powder metallurgy, characterized in that the compounding amount of the metal compound powder is 0.01 to 1.0% by mass% with respect to the total amount of the metal powder, the alloy powder and the machinability improving powder. .
（９）（７）または（８）において、前記金属粉末が、鉄基粉末であることを特徴とする粉末冶金用混合粉の製造方法。 ( 9 ) The method for producing a powder mixture for powder metallurgy, wherein the metal powder is an iron-based powder in ( 7 ) or ( 8 ).
（１０）（９）おいて、前記硬質金属化合物粉末が、金属ホウ化物粉末であることを特徴とする粉末冶金用混合粉の製造方法。 ( 10 ) In ( 9 ), the said hard metal compound powder is a metal boride powder, The manufacturing method of the mixed powder for powder metallurgy characterized by the above-mentioned.
（１１）（１０）において、前記金属ホウ化物粉末が、TiB２粉末、ZrB２粉末、NbB２粉末のうちから選ばれた１種または２種以上であることを特徴とする粉末冶金用混合粉の製造方法。 ( 11 ) In ( 10 ), the metal boride powder is one or more selected from TiB 2 powder, ZrB 2 powder, and NbB 2 powder. Manufacturing method.
（１２）（９）ないし（１１）のいずれかにおいて、前記軟質金属化合物粉末が、タルク粉末、エンスタタイト粉末、カオリン粉末、マイカ粉末、粘土粉末、蛍石粉末、水砕スラグ粉末のうちから選ばれた１種または２種以上であることを特徴とする粉末冶金用混合粉の製造方法。 ( 12 ) In any one of ( 9 ) to ( 11 ), the soft metal compound powder is selected from talc powder, enstatite powder, kaolin powder, mica powder, clay powder, fluorite powder, and granulated slag powder. A method for producing a powder mixture for powder metallurgy, characterized in that it is one kind or two or more kinds.
（１３）（７）ないし（１２）のいずれかに記載の製造方法で製造された混合粉を、金型に装入し、所定の圧力で圧粉成形して成形体とする成形工程と、該成形体に焼結処理を施して焼結体とする焼結工程とを順次施すことを特徴とする切削性に優れた焼結体の製造方法。 ( 13 ) A molding step in which the mixed powder produced by the production method according to any one of ( 7 ) to ( 12 ) is inserted into a mold and compacted at a predetermined pressure to form a molded body, A method for producing a sintered body excellent in machinability, characterized by sequentially performing a sintering process on the formed body by subjecting the molded body to a sintered body.
本発明によれば、優れた旋削性と、優れたドリル切削性とを兼備した、切削性に優れた焼結体を安価に製造でき、産業上格段の効果を奏する。また、本発明によれば、成形時には、圧粉密度の低下や、抜出力の増大を招くことなく成形でき、さらに、焼結時には、焼結炉の炉内環境に悪影響を及ぼすこともなく焼結できるという効果もある。また、本発明によれば、焼結部品の機械加工コストの飛躍的な低減が可能になるという効果もある。 ADVANTAGE OF THE INVENTION According to this invention, the sintered compact which was excellent in machinability which combined the outstanding turning property and the outstanding drill machinability can be manufactured at low cost, and there exists a remarkable effect on industry. In addition, according to the present invention, molding can be performed without causing a reduction in the density of the dust and an increase in the extraction force. Further, during sintering, the sintering can be performed without adversely affecting the furnace environment of the sintering furnace. There is also an effect that can be concluded. Further, according to the present invention, there is an effect that the machining cost of the sintered part can be drastically reduced.
まず、本発明の粉末冶金用混合粉について説明する。 First, the mixed powder for powder metallurgy according to the present invention will be described.
本発明の粉末冶金用混合粉は、金属粉末と、合金用粉末と、さらに切削性改善用粉末と、潤滑剤粉末と、を混合してなる混合粉である。 The mixed powder for powder metallurgy of the present invention is a mixed powder obtained by mixing a metal powder, an alloy powder, a machinability improving powder, and a lubricant powder.
本発明では、金属粉末としては、アルミニウム粉、あるいは、アトマイズ鉄粉および還元鉄粉などの純鉄粉、合金元素を予め合金化した予合金鋼粉（完全合金化鋼粉）、あるいは鉄粉に合金元素が部分拡散し合金化された部分拡散合金化鋼粉、あるいは予合金化鋼粉（完全合金化鋼粉）にさらに合金元素を部分拡散させたハイブリッド鋼粉などの鉄基粉末がいずれも適用できる。また、鉄基粉末としては、上記した鉄基粉末に加えてさらに合金用粉末、および潤滑剤粉末を混合した鉄基粉末混合粉としてもよい。 In the present invention, the metal powder may be aluminum powder, pure iron powder such as atomized iron powder and reduced iron powder, prealloyed steel powder (alloyed steel powder) in which alloying elements are prealloyed, or iron powder. Iron-base powders such as partially diffused alloyed steel powders that have been partially diffused and alloyed, or hybrid steel powders in which alloy elements have been further partially diffused into prealloyed steel powder (fully alloyed steel powder) Applicable. The iron-based powder may be an iron-based powder mixed powder obtained by further mixing an alloy powder and a lubricant powder in addition to the above-described iron-based powder.
また、合金用粉末としては、黒鉛粉末、Cu（銅）粉末、Mo粉末、Ni粉末などの非鉄金属粉末、亜酸化銅粉末などが例示され、所望の焼結体特性に応じて選択して混合する。これらの合金用粉末を、鉄基粉末に混合させることにより焼結体の強度を上昇させることができ、所望の焼結部品強度を確保できる。なお、合金用粉末の配合量は、所望の焼結体強度に応じて、金属粉末、合金用粉末、切削性改善用粉末の合計量に対する質量％で、0.1〜10％程度とすることが好ましい。合金用粉末の配合量が、0.1質量％未満では、所望の焼結体強度を確保できなくなる。一方、10質量％を超えて添加すると、焼結体の寸法精度が低下する。 Examples of alloy powders include non-ferrous metal powders such as graphite powder, Cu (copper) powder, Mo powder, Ni powder, and cuprous oxide powder, which are selected and mixed according to the desired sintered body characteristics. To do. By mixing these alloy powders with iron-based powder, the strength of the sintered body can be increased, and a desired sintered part strength can be ensured. The blending amount of the alloy powder is preferably about 0.1 to 10% in mass% with respect to the total amount of the metal powder, the alloy powder, and the machinability improving powder, depending on the desired strength of the sintered body. . If the blending amount of the alloy powder is less than 0.1% by mass, the desired sintered body strength cannot be secured. On the other hand, when it exceeds 10 mass%, the dimensional accuracy of a sintered compact will fall.
また、本発明では、切削性改善用粉末を、軟質金属化合物粉末（軟質材粉末）と硬質金属化合物粉末（硬質材粉末）とを混合した粉末とする。 In the present invention, the machinability improving powder is a powder obtained by mixing a soft metal compound powder (soft material powder) and a hard metal compound powder (hard material powder).
なお、ここでいう「軟質金属化合物粉末（軟質材粉末）」とは、混合粉を成形、焼結して得られた焼結体の基地相の平均硬さより低い硬さを有する金属化合物（軟質材）からなる粉末をいい、また、「硬質金属化合物粉末（硬質材粉末）」とは、混合粉を成形、焼結して得られた焼結体の基地相の平均硬さより高い硬さを有する金属化合物（硬質材）からなる粉末をいうものとする。 The “soft metal compound powder (soft material powder)” referred to here is a metal compound having a hardness lower than the average hardness of the matrix phase of the sintered body obtained by molding and sintering the mixed powder (soft The “hard metal compound powder (hard material powder)” means a hardness higher than the average hardness of the matrix phase of the sintered body obtained by molding and sintering the mixed powder. It shall mean the powder which consists of a metal compound (hard material) which has.
なお、均一分散性の観点から、軟質金属化合物粉末（軟質材粉末）の平均粒径は0.01〜20μm程度とすることが好ましい。また、焼結体の強度低下を防止する観点から、硬質金属化合物粉末（硬質材粉末）の平均粒径は0.01〜10μm程度とすることが好ましい。平均粒径は、レーザ回析法を利用して求めたものを使用するものとする。 From the viewpoint of uniform dispersibility, the average particle size of the soft metal compound powder (soft material powder) is preferably about 0.01 to 20 μm. Further, from the viewpoint of preventing the strength of the sintered body from decreasing, the average particle size of the hard metal compound powder (hard material powder) is preferably about 0.01 to 10 μm. The average particle size is determined by using a laser diffraction method.
例えば、Fe−Cu−Ｃ系鉄基粉末焼結体（金属粉末としての鉄基粉末と、合金用粉末としての黒鉛粉および銅粉とを用いた場合）では、焼結体の基地相を形成する組織は、フェライト相（α−鉄）およびパーライト相であり、通常、基地相は概ね100〜300HV程度（A.Salak, M.Selewcka and H.Danninger：Machinability of Powder Metallurgy Steels，p.369，（2005）、発行元：Elsevier社参照）の平均硬さを有する。そこで、本発明では、Fe−Cu−Ｃ系鉄基粉末（金属粉末としての鉄基粉末と、合金用粉末としての黒鉛粉および銅粉とを用いた場合）では、焼結体の基地相の平均硬さを、200 HV（モース硬度約４）と定義し、混合粉に切削性改善用粉末として添加する軟質金属化合物粉末（軟質材粉末）は、この硬さ（焼結体の基地相の平均硬さ）より軟質である、すなわち、モース硬度４以下の金属化合物粉末の中から選ばれた１種または２種以上とし、一方、硬質金属化合物粉末（硬質材粉末）は、焼結体の基地相の平均硬さより硬質である、すなわち、モース硬度４超えの硬さを有する金属化合物粉末の中から選ばれた１種または２種以上とする。 For example, the Fe-Cu-C iron-based powder sintered body (when iron-based powder as metal powder and graphite powder and copper powder as alloy powder are used) forms the base phase of the sintered body The structure to be formed is a ferrite phase (α-iron) and a pearlite phase, and the base phase is generally about 100 to 300 HV (A. Salak, M. Selewcka and H. Danninger: Machinability of Powder Metallurgy Steels, p. 369, (2005), publisher: Elsevier, Inc.). Therefore, in the present invention, the Fe-Cu-C-based iron-based powder (in the case of using iron-based powder as metal powder and graphite powder and copper powder as alloy powder) The average hardness is defined as 200 HV (Mohs hardness of about 4), and the soft metal compound powder (soft material powder) added to the mixed powder as a machinability improving powder has this hardness (base phase of the sintered body). Average hardness), that is, one or more selected from metal compound powders having a Mohs hardness of 4 or less, while hard metal compound powders (hard material powders) are One or more selected from metal compound powders that are harder than the average hardness of the matrix phase, that is, have a Mohs hardness of more than 4.
なお、モース硬度４以下の金属化合物としては、例えば、タルク、エンスタタイト、カオリン、マイカ、粘土、蛍石等の軟質鉱物、または水砕スラグ（脱酸生成物）などが例示でき、水砕スラグとしては、CaO−SiO２−Al２O３，MgO−Al２O３−SiO２等の成分系で代表される脱酸生成物が例示できる。 Examples of the metal compound having a Mohs hardness of 4 or less include soft minerals such as talc, enstatite, kaolin, mica, clay, and fluorite, or granulated slag (deoxidation product). Examples thereof include deoxidation products represented by component systems such as CaO—SiO 2 —Al 2 O 3 and MgO—Al 2 O 3 —SiO 2 .
また、モース硬度４超えの金属化合物としては、例えば、各種セラミックスがそれに該当するが、なかでも金属ホウ化物が好適である。そして、金属ホウ化物のなかでも、とりわけTiB２、ZrB２、NbB２が好ましい。 Examples of the metal compound having a Mohs hardness of more than 4 include various ceramics, and metal borides are particularly preferable. Of the metal borides, TiB 2 , ZrB 2 , and NbB 2 are particularly preferable.
なお、本発明混合粉における軟質金属化合物粉末（軟質材粉末）の配合量は合計で、金属粉末、合金用粉末、切削性改善用粉末の合計量に対する質量％で、0.01〜1.0 ％程度とすることが好ましい。配合量が0.01質量％未満では、加圧成形時における成形体密度の向上や、成形体抜出時における抜出力の十分な低減が、できなくなる。一方、1.0％を超えて配合すると、圧粉体密度が低下し、さらには成形体を焼結して得た焼結体の機械的強度が低下する恐れがある。このため、混合粉における軟質金属化合物粉末（軟質材粉末）の配合量は合計で、0.01〜1.0質量％の範囲に限定することが好ましい。 The total amount of the soft metal compound powder (soft material powder) in the mixed powder of the present invention is about 0.01 to 1.0% in terms of mass% with respect to the total amount of metal powder, alloy powder, and machinability improving powder. It is preferable. When the blending amount is less than 0.01% by mass, it is impossible to improve the density of the molded body at the time of pressure molding and sufficiently reduce the extraction output at the time of extracting the molded body. On the other hand, when it exceeds 1.0%, the green compact density is lowered, and further, the mechanical strength of the sintered body obtained by sintering the molded body may be lowered. For this reason, it is preferable to limit the compounding quantity of the soft metal compound powder (soft material powder) in mixed powder to the range of 0.01-1.0 mass% in total.
一方、本発明混合粉における硬質金属化合物粉末（硬質材粉末）の配合量は合計で、金属粉末、合金用粉末、切削性改善用粉末の合計量に対する質量％で、0.01〜0.5％程度とすることが好ましい。硬質金属化合物粉末の配合量が、0.01％未満では、加圧成形時における成形体密度の向上や、成形体抜出時における抜出力の十分な低減が、できなくなる。一方、0.5％を超えて配合すると、圧粉体密度が低下し、さらには成形体を焼結して得た焼結体の機械的強度が低下する恐れがある。このため、混合粉における硬質金属化合物粉末の配合量は合計で質量％で、0.01〜0.5％の範囲に限定することが好ましい。 On the other hand, the blending amount of the hard metal compound powder (hard material powder) in the mixed powder of the present invention is a total, and is about 0.01 to 0.5% by mass% with respect to the total amount of the metal powder, the alloy powder, and the machinability improving powder. It is preferable. When the blending amount of the hard metal compound powder is less than 0.01%, it becomes impossible to improve the density of the molded body at the time of pressure molding and sufficiently reduce the output at the time of extracting the molded body. On the other hand, when it exceeds 0.5%, the green compact density is lowered, and further, the mechanical strength of the sintered body obtained by sintering the molded body may be lowered. For this reason, it is preferable to limit the compounding quantity of the hard metal compound powder in mixed powder to the range of 0.01 to 0.5% by the mass% in total.
上記したように、切削性改善用粉末として軟質金属化合物粉末および硬質金属化合物粉末を配合した混合粉を成形し、焼結すると、基地相中に、軟質金属化合物粒子が質量％で0.01〜1.0％、硬質金属化合物粒子が質量％で0.01〜0.5％、それぞれ分散した焼結体が得られる。基地相中に軟質金属化合物粒子が質量％で0.01〜1.0％分散していることにより、切削時に、切屑の変形抵抗を低減し、切削工具に作用する応力を低減でき、工具寿命が向上する。またさらに、基地相中に硬質金属化合物粒子が質量％で0.01〜0.5％、分散していることにより、切削時に形成された切屑が変形する際に、硬質金属化合物粒子が応力集中点となり、切屑の微細化が可能となり、例えばドリル切削時の切屑の排出が促進され、ドリル切削性が向上する。軟質金属化合物粒子および硬質金属化合物粒子が上記した分散量を外れて分散すると、切削性改善の程度が少ないか、機械的特性が低下する。 As described above, when a mixed powder containing soft metal compound powder and hard metal compound powder is molded and sintered as a powder for improving machinability, the soft metal compound particles are 0.01% to 1.0% by mass in the matrix phase. A sintered body in which hard metal compound particles are dispersed in an amount of 0.01 to 0.5% by mass is obtained. When the soft metal compound particles are dispersed in the matrix phase by 0.01 to 1.0% by mass, the deformation resistance of chips can be reduced during cutting, the stress acting on the cutting tool can be reduced, and the tool life is improved. Furthermore, since the hard metal compound particles are dispersed in the matrix phase in an amount of 0.01 to 0.5% by mass, when the chips formed at the time of cutting are deformed, the hard metal compound particles become stress concentration points, and the chips. Therefore, for example, chip discharge during drill cutting is promoted, and drill cutting performance is improved. If the soft metal compound particles and the hard metal compound particles are dispersed out of the above-described dispersion amount, the degree of improvement in machinability is small or the mechanical properties are deteriorated.
本発明混合粉には、上記した金属粉末、合金用粉末、切削性改善用粉末に加えて、適正量の潤滑剤を配合する。配合される潤滑剤としては、ステアリン酸亜鉛、ステアリン酸リチウム等の金属石鹸、あるいはオレイン酸などのカルボン酸、ステアリン酸アミド、ステアリン酸ビスアミド、エチレンビスステアロアミドなどの、アミドワックスが好ましい。潤滑剤の配合量は、本発明ではとくに限定されないが、金属粉末、合金用粉末、切削性改善用粉末の合計量100質量部に対し、0.1〜1.0質量部とすることが好ましい。潤滑剤の配合量が、0.1質量部未満では、金型との摩擦が増加し抜き出し力が増大し、金型寿命が低下する。一方、1.0質量部を超えて多量となると、成形密度が低下し、焼結体密度が低くなる。 In addition to the above metal powder, alloy powder, and machinability improving powder, an appropriate amount of lubricant is blended in the mixed powder of the present invention. The lubricant to be blended is preferably a metal soap such as zinc stearate or lithium stearate, or an amide wax such as carboxylic acid such as oleic acid, stearic acid amide, stearic acid bisamide, or ethylene bisstearamide. The blending amount of the lubricant is not particularly limited in the present invention, but is preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the total amount of the metal powder, the alloy powder, and the machinability improving powder. When the blending amount of the lubricant is less than 0.1 parts by mass, the friction with the mold increases, the extraction force increases, and the mold life decreases. On the other hand, if the amount exceeds 1.0 part by mass, the molding density decreases and the sintered body density decreases.
つぎに、本発明混合粉の好ましい製造方法について、金属粉末を鉄基粉末とした場合を例に、説明するが、これに限定されるものではないことは言うまでもない。 Next, a preferred method for producing the mixed powder of the present invention will be described by taking the case where the metal powder is an iron-based powder as an example, but it is needless to say that the present invention is not limited thereto.
鉄基粉末に、合金用粉末、および、軟質金属化合物粉末と硬質金属化合物粉末とからなる切削性改善用粉末、さらに潤滑剤を、それぞれ所定量配合し、通常公知の混合機を用いて、一回に、あるいは二回以上に分けて混合し、混合粉（鉄基混合粉）とすることが望ましい。上記した軟質金属化合物粉末および硬質金属化合物粉末は、必ずしも全量を一度に混合する必要はなく、一部のみを配合して混合（一次混合）したのち、残部を二次混合材として配合し混合（二次混合）することもできる。なお、潤滑剤も、二回に分けて配合してもよい。 A predetermined amount of each of an iron-based powder, an alloy powder, a powder for improving machinability composed of a soft metal compound powder and a hard metal compound powder, and a lubricant is blended, and the mixture is mixed using a generally known mixer. It is desirable to mix in one or two or more times to obtain a mixed powder (iron-based mixed powder). The above-mentioned soft metal compound powder and hard metal compound powder do not necessarily need to be mixed all at once, and after mixing and mixing (primary mixing) only a part, the remainder is mixed and mixed as a secondary mixture ( (Secondary mixing). In addition, you may mix | blend a lubricant in two steps.
なお、鉄基粉末の一部または全部に、偏析防止処理を施され結合材により表面に合金用粉末および／または切削性改善用粉末の一部または全部を固着させた鉄基粉末を用いても良い。なお、偏析防止処理としては、特許第3004800号公報に記載の方法を用いることができる。 It is also possible to use an iron-based powder in which a segregation preventing treatment is applied to a part or all of the iron-based powder and a part or all of the alloying powder and / or the machinability improving powder is fixed to the surface by a binder. good. As the segregation prevention treatment, the method described in Japanese Patent No. 3004800 can be used.
また、鉄基粉末に、合金用粉末、および、軟質金属化合物粉末と硬質金属化合物粉末とからなる切削性改善用粉末を、潤滑剤とともに所定量配合して、該潤滑剤の融点のうちの最低値以上に加熱し、少なくとも１種の潤滑剤を溶融させて、混合したのち、所定の温度以下に冷却して固化させる一次混合を行ない、さらに、二次混合材を添加し、混合する二次混合を行なってもよい。 In addition, a predetermined amount of a powder for alloying and a machinability improving powder made of a soft metal compound powder and a hard metal compound powder are blended together with the lubricant in the iron-based powder, and the lowest melting point of the lubricant Heating above the value, melting and mixing at least one lubricant, followed by primary mixing to cool and solidify by cooling to a predetermined temperature or lower, and further adding a secondary mixture and mixing Mixing may be performed.
また、混合手段としては、とくに制限はなく、従来公知の混合機いずれもが使用できる。なお、加熱が容易な、高速底部撹拌式混合機、傾斜回転パン型混合機、回転クワ型混合機および円錐遊星スクリュー形混合機などは特に有利に適合する。 The mixing means is not particularly limited, and any conventionally known mixer can be used. Note that a high-speed bottom-stirring mixer, an inclined rotary pan mixer, a rotary mulberry mixer, a conical planetary screw mixer, and the like that are easy to heat are particularly advantageous.
つぎに、上記した製造方法で製造された本発明の粉末冶金用混合粉を用いた、焼結体の好ましい製造方法について説明する。 Below, the preferable manufacturing method of a sintered compact using the mixed powder for powder metallurgy of this invention manufactured with the above-mentioned manufacturing method is demonstrated.
まず、好ましくは上記した方法で製造された、本発明の粉末冶金用混合粉を、金型に充填し圧縮成形し、成形体とする。成形方法は、プレス等の通常の成形方法がいずれも好適である。なお、本発明の粉末冶金用混合粉を用いることにより、成形圧力を294MPa以上とすることができ、さらに常温においても成形することができる。なお、安定した成形性を確保するためには、混合粉や金型を適正な温度に加熱したり、金型に潤滑剤を塗布することが好ましい。 First, the mixed powder for powder metallurgy according to the present invention, which is preferably produced by the method described above, is filled into a mold and compression molded to obtain a molded body. As the molding method, any ordinary molding method such as a press is suitable. By using the mixed powder for powder metallurgy according to the present invention, the molding pressure can be increased to 294 MPa or more, and further, molding can be performed at room temperature. In order to secure stable moldability, it is preferable to heat the mixed powder or the mold to an appropriate temperature or apply a lubricant to the mold.
また、成形を、加熱雰囲気中で行う場合には、混合粉や金型の温度は150℃未満とすることが好ましい。というのは、本発明の混合粉は、圧縮性に富むため、150℃未満の温度でも優れた成形性を示すうえ、150℃以上になると酸化による劣化が懸念されるためである。 In addition, when molding is performed in a heated atmosphere, the temperature of the mixed powder or the mold is preferably less than 150 ° C. This is because the mixed powder of the present invention is excellent in compressibility, so that it exhibits excellent moldability even at a temperature of less than 150 ° C., and at the temperature of 150 ° C. or higher, there is a concern about deterioration due to oxidation.
得られた成形体は、ついで焼結処理を施され、焼結体となる。焼結処理の温度は、金属粉末の融点の約70％の温度で行う。鉄基粉末の場合、1000℃以上好ましくは1300℃以下とする。焼結処理の温度が1000℃未満では、所望の密度の焼結体とすることが難しくなる。なお、焼結処理の温度が1300℃を超えて高温となると、異常粒成長が起こり、焼結体強度が低下する。 The obtained molded body is then subjected to a sintering treatment to become a sintered body. The temperature of the sintering process is about 70% of the melting point of the metal powder. In the case of iron-based powder, the temperature is set to 1000 ° C or higher, preferably 1300 ° C or lower. When the sintering temperature is less than 1000 ° C., it becomes difficult to obtain a sintered body having a desired density. When the temperature of the sintering process exceeds 1300 ° C. and becomes high, abnormal grain growth occurs and the strength of the sintered body decreases.
また、焼結処理の雰囲気は、窒素あるいはアルゴンなどの不活性雰囲気、あるいは、これに水素を混合した不活性ガス−水素ガス混合雰囲気、あるいは、アンモニア分解ガス、RXガス、天然ガスなどの還元雰囲気とすることが好ましい。 In addition, the sintering atmosphere can be an inert atmosphere such as nitrogen or argon, an inert gas-hydrogen gas mixed atmosphere in which hydrogen is mixed with this, or a reducing atmosphere such as ammonia decomposition gas, RX gas, natural gas, etc. It is preferable that
焼結処理後、さらに、必要に応じて、ガス浸炭熱処理や浸炭窒化処理等の熱処理を施し、所望の特性を具備された製品（焼結部品等）とすることができる。なお、切削加工等の加工を随時施し、所定寸法の製品とすることは言うまでもない。 After the sintering treatment, a heat treatment such as a gas carburizing heat treatment or a carbonitriding treatment may be performed as necessary to obtain a product (sintered part or the like) having desired characteristics. Needless to say, processing such as cutting is performed as needed to obtain a product with a predetermined size.
以下、実施例に基づき、さらに本発明を具体的に説明する。 Hereinafter, based on an Example, this invention is demonstrated further more concretely.
金属粉末として、表１に示す鉄基粉末（いずれも平均粒径：約80μm）を使用した。使用した鉄基粉末は、アトマイズ純鉄粉（Ａ）、還元純鉄粉（Ｂ）、鉄粉表面に合金元素としてCuを部分拡散させ合金化した部分拡散合金化鋼粉（Ｃ）、鉄粉表面に合金元素としてNi、Cu、Moを部分拡散させ合金化した部分拡散合金化鋼粉（Ｄ）、合金元素としてNi、Moを予合金化した予合金化鋼粉（完全合金化鋼粉）（Ｅ）、合金元素としてMoを予合金化した予合金化鋼粉（完全合金化鋼粉）（Ｆ）とした。 As the metal powder, iron-based powder shown in Table 1 (both average particle diameter: about 80 μm) was used. The iron-based powder used is atomized pure iron powder (A), reduced pure iron powder (B), partially diffused alloyed steel powder (C), which is alloyed by partially diffusing Cu as an alloy element on the iron powder surface, iron powder Partially-diffused alloyed steel powder (D), which is alloyed by partially diffusing Ni, Cu, Mo as alloy elements on the surface, pre-alloyed steel powder (fully-alloyed steel powder) pre-alloyed with Ni, Mo as alloy elements (E), prealloyed steel powder (fully alloyed steel powder) (F) in which Mo was prealloyed as an alloy element.
上記した鉄基粉末に、表２に示す種類、配合量の合金用粉末と、表２に示す種類、配合量の切削性改善用粉末と、さらに、表２に示す種類、配合量の潤滑剤とを、配合し、高速底部撹拌式混合機を利用して、一次混合した。なお、一次混合では、混合しながら140℃に加熱し、少なくとも１種の潤滑剤を溶融させた後、60℃以下に冷却した。なお、合金用粉末として配合した天然黒鉛粉は平均粒径：５μmの粉末であり、銅粉は平均粒径：25μmの粉末とした。 The above-mentioned iron-based powder, the types and amounts of alloy powder shown in Table 2, the types and amounts of cutting powder for improving machinability shown in Table 2, and the types and amounts of lubricant shown in Table 2 Were mixed and primary mixed using a high speed bottom stirring mixer. In the primary mixing, the mixture was heated to 140 ° C. while mixing to melt at least one lubricant and then cooled to 60 ° C. or lower. The natural graphite powder blended as the alloy powder was a powder having an average particle diameter of 5 μm, and the copper powder was a powder having an average particle diameter of 25 μm.
一次混合したのち、さらに表２に示す種類、配合量の切削性改善用粉末、潤滑剤からなる二次混合材を配合し、混合機の回転数を500rpmとし、１分間撹拌する、二次混合を行なった。二次混合後、混合機から混合粉を排出した。 After the primary mixing, mix the secondary mixing material consisting of the types and blending amounts of the powders for improving machinability and the lubricant shown in Table 2 and stir for 1 minute with the mixer rotating at 500 rpm. Was done. After the secondary mixing, the mixed powder was discharged from the mixer.
なお、切削性改善用粉末は、軟質金属化合物粉末（軟質材粉末）および硬質金属化合物粉末（硬質材粉末）とし、一次混合時および／または二次混合時に配合した。切削性改善用粉末の配合量は、鉄基粉末、合金用粉末、切削性改善用粉末の合計量に対する質量％で表示し、潤滑剤の配合量は、鉄基粉末、合金用粉末、切削性改善用粉末の合計量100質量部に対する質量部で表示した。 Note that the machinability improving powder was a soft metal compound powder (soft material powder) and a hard metal compound powder (hard material powder), and was mixed during primary mixing and / or secondary mixing. The compounding amount of the powder for improving machinability is expressed in mass% with respect to the total amount of the iron-based powder, alloy powder and powder for improving machinability, and the compounding amount of the lubricant is iron-based powder, alloy powder and machinability. Displayed in parts by mass relative to 100 parts by mass of the total amount of powder for improvement.
これにより、鉄基粉末、合金用粉末、切削性改善用粉末が、偏析を生じることなく、均一に混合された混合粉が得られた。 As a result, a mixed powder was obtained in which the iron-based powder, the alloy powder, and the machinability improving powder were uniformly mixed without causing segregation.
なお、比較例として、表２に示す種類、配合量の、鉄基粉末、合金用粉末、潤滑剤、あるいはさらに本発明の範囲を外れる配合量の切削性改善用粉末を配合し、Ｖ型容器回転式混合機を用いて、常温で混合し、混合粉を得た。 In addition, as a comparative example, the types and blending amounts shown in Table 2 were mixed with iron-based powders, alloy powders, lubricants, or further blending amounts of powders outside the scope of the present invention. Using a rotary mixer, mixing was performed at room temperature to obtain a mixed powder.
得られた混合粉を、金型（旋盤切削試験用およびドリル切削試験用の２種）に装入し、加圧力：590MPaで圧粉成形し、成形体を得た。ついで、得られた成形体に、ＲＸガス雰囲気中で、1130℃×20minの焼結処理を施して、焼結体（旋盤切削試験用：外径60mm×内径20mm×長さ20mm、ドリル切削試験用：外径60mm×厚さ10mm）を得た。 The obtained mixed powder was charged into a mold (two types for lathe cutting test and drill cutting test) and compacted at a pressure of 590 MPa to obtain a molded body. Next, the obtained compact was sintered in RX gas atmosphere at 1130 ° C x 20 min, and the sintered compact (for lathe cutting test: outer diameter 60 mm x inner diameter 20 mm x length 20 mm, drill cutting test Use: outer diameter 60 mm × thickness 10 mm).
得られた焼結体について、旋盤切削試験、ドリル切削試験を実施した。試験方法は次のとおりとした。 About the obtained sintered compact, the lathe cutting test and the drill cutting test were implemented. The test method was as follows.
（１）旋盤切削試験
得られた焼結体（リング状：外径60mm×内径20mm×長さ20mm）を３個重ねて、その側面を、旋盤を用いて切削した。切削条件は、超硬の切削工具を用いて、切削速度：200m／min、送り量：0.1mm／回、切込み深さ：0.5mm，切削距離：1000mとし、切削後、切削工具の逃げ面の摩耗幅を測定した。切削工具の逃げ面の摩耗幅が小さいほど、旋削性に優れていると評価した。
(1) Lathe cutting test Three of the obtained sintered bodies (ring shape: outer diameter 60 mm x inner diameter 20 mm x length 20 mm) were stacked and the side surfaces were cut using a lathe. Cutting conditions were as follows: Carbide cutting tool, cutting speed: 200 m / min, feed rate: 0.1 mm / turn, depth of cut: 0.5 mm, cutting distance: 1000 m. The wear width was measured. The smaller the wear width of the flank of the cutting tool, the better the turning performance.
（２）ドリル切削試験
得られた焼結体（円盤状：外径60mm×厚さ10mm）に、高速度鋼製ドリル（直径：1.2mmのシャンクドリル）で、回転数：10,000rpm、送り速度：300mm／minの条件で貫通穴を穿孔し、ドリルが破損するまでの穿孔数を調査し、穿孔数が多いほどドリル切削性に優れていると評価した。なお、穿孔部表面のバリ発生の有無を目視で調査した。
(2) Drill cutting test The obtained sintered body (disk shape: outer diameter 60 mm x thickness 10 mm) was rotated with a high-speed steel drill (diameter: 1.2 mm shank drill), rotation speed: 10,000 rpm, feed rate : Drilled through holes under the condition of 300 mm / min, investigated the number of drill holes until the drill breaks, and evaluated that the greater the number of drill holes, the better the drill machinability. In addition, the presence or absence of burr | flash generation | occurrence | production of the perforated part surface was investigated visually.
得られた結果を、表３に示す。 The results obtained are shown in Table 3.
本発明はいずれも、切削工具の逃げ面の摩耗幅が小さく、旋盤切削性（旋削性）に優れ、さらにドリルが破損するまでの穿孔数が多く、またバリの発生もなくドリル切削性にも優れ、優れた旋削性および優れたドリル切削性を兼備した焼結体となっている。一方、本発明の範囲を外れる比較例は、旋削性および／またはドリル切削性が低下していた。 In any of the present inventions, the wear width of the flank of the cutting tool is small, the lathe machinability (turning) is excellent, the number of drill holes until the drill breaks is large, and there is no generation of burrs and drill machinability. It is a sintered body that combines excellent and excellent turning properties and excellent drillability. On the other hand, in the comparative example outside the scope of the present invention, the turning property and / or the drill cutting property were lowered.
Claims (6)
前記金属粉末が、鉄基粉末で、
前記切削性改善用粉末が、軟質金属化合物粉末と、硬質金属化合物粉末とからなり、
該軟質金属化合物粉末が、タルク粉末、エンスタタイト粉末、カオリン粉末、マイカ粉末、粘土粉末、蛍石粉末、水砕スラグ粉末のうちから選ばれた１種または２種以上で、
該硬質金属化合物粉末が、金属ホウ化物粉末である
ことを特徴とする粉末冶金用混合粉。 A mixed powder for powder metallurgy obtained by mixing metal powder, alloy powder, further machinability improving powder, and lubricant powder,
The metal powder is an iron-based powder,
The machinability improving powder is a soft metal compound powder, Ri Do and a hard metal compound powder,
The soft metal compound powder is one or more selected from talc powder, enstatite powder, kaolin powder, mica powder, clay powder, fluorite powder, and granulated slag powder,
Rigid metal compound powder is a powder metallurgical mixed powder, wherein the metal boride powder der Rukoto.
前記粉末冶金用混合粉が、金属粉末と、合金用粉末と、さらに軟質金属化合物粉末と硬質金属化合物粉末とからなる切削性改善用粉末と、潤滑剤粉末とを混合してなる粉末冶金用混合粉であり、
前記金属粉末を鉄基粉末とし、
前記焼結体の基地相中に、該基地相の平均硬さより低い硬さの軟質金属化合物の粒子と、前記基地相の平均硬さより高い硬さの硬質金属化合物の粒子とが分散してなり、
前記軟質金属化合物が、タルク、エンスタタイト、カオリン、マイカ、粘土、蛍石、水砕スラグのうちから選ばれた１種または２種以上からなり、前記硬質金属化合物が、金属ホウ化物（但し、Cr、Fe、Ｃ、Ｂとが反応して形成された硬質の複合炭、硼化物である場合を除く）であることを特徴とする優れた切削性を有する金属粉末製焼結体。 It is a sintered body formed by molding and sintering mixed powder for powder metallurgy,
The powder metal blend powder, a metal powder, an alloy powder, further the machinability improvement powder comprising a soft metal compound powder and the hard quality metal compound powder, powder metallurgy obtained by mixing the lubricant powder Mixed powder,
The metal powder is an iron-based powder,
In the matrix phase of the sintered body, particles of a soft metal compound having a hardness lower than the average hardness of the matrix phase and particles of a hard metal compound having a hardness higher than the average hardness of the matrix phase are dispersed. The
The soft metal compound is one or more selected from talc, enstatite, kaolin, mica, clay, fluorite, and granulated slag, and the hard metal compound is a metal boride (however, cr, Fe, C, complex carbonitride rigid and is formed by the reaction B, except when a boride) metal powder made sintered body having excellent machinability, characterized in der Rukoto.
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| JP4188440B2 (en) * | 1997-10-17 | 2008-11-26 | 大豊工業株式会社 | Copper-based sintered sliding material with excellent sliding characteristics and machinability |
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