JP5962691B2 - Mixed powder for powder metallurgy, production method thereof, and sintered body made of iron-based powder - Google Patents
Mixed powder for powder metallurgy, production method thereof, and sintered body made of iron-based powder Download PDFInfo
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本発明は、自動車焼結部品用などに好適な、鉄基粉末、合金用粉末、切削性改善用粉末および潤滑剤を混合した粉末冶金用混合粉とその製造方法、ならびに、この混合粉を成形、焼結して得られる鉄基粉末製焼結体に関するものであって、特に、鉄基粉末製焼結体の切削性改善を図ろうとするものである。 The present invention relates to a powder for powder metallurgy mixed with an iron-based powder, an alloy powder, a machinability improving powder and a lubricant, suitable for automobile sintered parts, and a method for producing the same, and molding the mixed powder. The present invention relates to a sintered body made of iron-based powder obtained by sintering, and particularly aims to improve the machinability of the sintered body made of iron-based powder.
粉末冶金技術の進歩によって、高寸法精度で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ったため、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、成形した後、焼結を行うことから、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 complex shapes with high dimensional accuracy in a near net shape, and therefore products using powder metallurgy technology are used in various fields. The powder metallurgy technique is characterized by a high degree of freedom in shape because powder is filled in a mold having a desired shape, and then sintered. For this reason, there are many cases of application to mechanical parts such as gears having complicated shapes.
また、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、近年では、極めて厳しい寸法精度が要求される場合があり、焼結した後に、さらに切削加工を施す必要が増えてきている。そして、この切削加工においては、旋盤による旋削や、ドリルによる穴あけなどの精密加工が、種々の切削速度で行われている。 In the field of iron-based powder metallurgy, an iron-based mixed powder in which an iron-based powder (metal powder) is mixed with a powder for an alloy such as copper powder or graphite powder and a lubricant such as zinc stearate or 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. Sintered parts obtained in this way are generally considered to have good dimensional accuracy. However, in recent years, extremely strict dimensional accuracy may be required, and it is necessary to perform further cutting after sintering. Is increasing. In this cutting process, precision machining such as turning with a lathe and drilling with a drill is performed at various cutting speeds.
しかし、上記焼結部品は、空孔の含有比率が高く、溶解法による金属材料にくらべると、切削抵抗が高くなる傾向にある。そのため、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、粉末で添加したり、鉄粉や鉄基粉末に合金化して添加したりすることが行なわれてきた。
ところが、Pbは融点が330℃と低いため、焼結過程で溶融するものの、鉄中には固溶しないので、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や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。
However, the sintered part has a high content ratio of voids, and tends to have higher cutting resistance than a metal material obtained by a melting method. Therefore, conventionally, for the purpose of improving the machinability of the sintered body, Pb, Se, Te, etc. are added to the iron-based mixed powder as a powder, or alloyed and added to the iron powder or iron-based powder. Has been done.
However, since Pb has a melting point as low as 330 ° C., it melts in the sintering process, but does not dissolve in iron, so that it 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.
さらに、上述した空孔は、熱伝導性が悪いために、焼結体を加工すると加工時の摩擦熱が蓄積されて、工具の表面温度が上がりやすくなる。そのため、切削工具が損耗し易くなって短寿命となる結果、切削加工費が増大して、焼結部品の製造コストの上昇を招くという問題もあった。 Furthermore, since the holes described above have poor thermal conductivity, when the sintered body is processed, frictional heat during processing is accumulated, and the surface temperature of the tool tends to increase. Therefore, the cutting tool is easily worn out and has a short life, resulting in an increase in cutting cost and an increase in manufacturing cost of the sintered part.
これらの問題に対し、例えば、特許文献１には、鉄粉に、10μm以下の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、大きな寸法変化および強度劣化を伴うことなく、焼結材の被削性（切削性）を改善できるとされている。
To deal with these problems, for example, Patent Document 1 describes an iron powder mixture for producing a sintered body in which 0.05 to 5% by weight of fine manganese sulfide powder of 10 μm or less is mixed with iron powder.
According to the technique described in Patent Document 1, it is said that the machinability (cutability) of the sintered material can be improved without causing a large dimensional change and strength deterioration.
特許文献２には、鉄基粉末に珪酸アルカリを添加する鉄基焼結体の製造方法が記載されている。
特許文献２に記載された技術によれば、珪酸アルカリを0.1〜1.0重量％添加することにより、大きな寸法変化および強度劣化を伴うことなく、快削性を改善できるとされている。
Patent Document 2 describes a method for producing an iron-based sintered body in which an alkali silicate is added to an iron-based powder.
According to the technique described in Patent Document 2, it is said that by adding 0.1 to 1.0% by weight of alkali silicate, free machinability can be improved without accompanying a large dimensional change and strength deterioration.
特許文献３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−SiO2系複合酸化物の粉末（セラミックス粉末）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３に記載された技術によれば、切削時に加工面に露出したセラミックス粉末が工具表面に付着して工具保護膜（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されている。
In Patent Document 3, a powder (ceramics powder) of CaO—Al 2 O 3 —SiO 2 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, is 0.02 to An iron-based mixed powder for powder metallurgy containing 0.3% by weight is described.
According to the technique described in Patent Document 3, the ceramic powder exposed on the work surface during cutting adheres to the tool surface to form a tool protective film (berak layer), and prevents material deterioration of the tool and improves machinability. It can be improved.
特許文献４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に加えて、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、硫化マンガンは切り屑の微細化に有効に作用する一方、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ベラーク層を形成し、工具表面の変質を防止または抑制する効果があると記載されている。
すなわち、特許文献４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されている。
Patent Document 4 discloses an iron-based powder obtained by mixing a lubricant in addition to manganese-based powder, calcium phosphate powder and / or hydroxyapatite powder as iron-based powder, alloy powder, and machinability improving powder. Have been described. Here, manganese sulfide works effectively to make chips finer, while calcium phosphate powder and hydroxyapatite powder adhere to the surface of the tool during cutting to form a veraque layer, thereby preventing or suppressing alteration of the tool surface. It is described as effective.
That is, according to the technique described in Patent Document 4, it is said that the machinability can be improved without deteriorating the mechanical properties of the sintered body.
また、特許文献５によれば、鉄または鉄基合金に、硫酸バリウムあるいは硫化バリウムを単独あるいは合計で0.3〜3.0重量％添加することにより、切削抵抗を低下することができるので、機械加工性を向上させることができると記載されている。 Further, according to Patent Document 5, cutting resistance can be reduced by adding barium sulfate or barium sulfide alone or in a total amount of 0.3 to 3.0% by weight to iron or an iron-based alloy. It is described that it can be improved.
しかしながら、特許文献１および４に記載された技術では、硫化マンガン（MnS）粉を含むため、焼結体外観の悪化の原因となるとともに、焼結体中に残留したＳあるいはMnSは、焼結部品の発錆を促進し、その耐食性を低下させるという問題がある。
さらに、MnSは、切削速度が100m/min以下という低速域での切削性改善には優れているものの、200m/min程度の高速切削では、切削性改善効果が小さいという課題がある。
However, in the techniques described in Patent Documents 1 and 4, since manganese sulfide (MnS) powder is included, the appearance of the sintered body is deteriorated, and S or MnS remaining in the sintered body is sintered. There is a problem that rusting of parts is promoted and its corrosion resistance is lowered.
Furthermore, although MnS is excellent in improving the machinability in a low speed region where the cutting speed is 100 m / min or less, there is a problem that the effect of improving the machinability is small in high speed cutting of about 200 m / min.
また、特許文献２に記載された技術では、切り屑が微細化しないために、ドリル切削の場合は、切り屑の排除性が悪く、ドリルの切削性にはいまだ問題を残している。 Further, in the technique described in Patent Document 2, since the chips are not miniaturized, in the case of drill cutting, the chip eliminability is poor, and the drill machinability still has a problem.
さらに、特許文献３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、セラミックス粉末中の不純物を少なくし、かつその粒度を調整した粉末とする必要があって、材料コストが高騰するという問題がある。また、特許文献３に記載された技術では、高速での切削性改善には優れるものの、低速での切削では切削性改善効果が小さいという課題がある。 Furthermore, in the technique described in Patent Document 3, it is necessary to reduce the impurities in the ceramic powder and to adjust the particle size in order to prevent deterioration of the powder characteristics and sintered body characteristics. There is a problem that the material cost increases. Moreover, although the technique described in Patent Document 3 is excellent in improving machinability at high speed, there is a problem that the effect of improving machinability is small in cutting at low speed.
加えて、特許文献３および４に記載されたベラーク層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ものの、切り屑が微細化しないために、ドリル切削の場合は、やはり、切り屑の排除性が悪く、ドリルの切削性にはいまだ問題を残している。 In addition, although the machinability improvement by the formation of the verak layer described in Patent Documents 3 and 4 is effective in reducing the cutting power in turning, the chip is not refined. The chip evacuation is poor, and the drill's machinability still remains a problem.
他方、特許文献５に記載された技術では、MnSを用いた技術と同様に、200m/min程度の高速切削における切削性改善効果が小さい、という課題がある。 On the other hand, the technique described in Patent Document 5 has a problem that the effect of improving the machinability in high-speed cutting of about 200 m / min is small as in the technique using MnS.
本発明は、上記した従来技術の問題や課題を有利に解決し、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、粉末冶金用混合粉およびその製造方法を提供することを目的とする。また、本発明では、その粉末冶金用混合粉を用いる、優れた旋削性およびドリル加工性を兼備する切削性に優れた鉄基粉末製焼結体を併せて提供することを目的とする。 The present invention advantageously solves the problems and problems of the prior art described above, and has excellent machinability, specifically, excellent lathe machinability (hereinafter also referred to as latheability) and excellent drill machinability. It is an object to provide a mixed powder for powder metallurgy capable of obtaining a body and a method for producing the same. Another object of the present invention is to provide an iron-based powder sintered body having excellent machinability, which has excellent turning properties and drillability, using the powder mixture for powder metallurgy.
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、鉄基粉末や、合金用粉末、潤滑剤と共に加える切削性改善用粉末（添加材）として、焼結処理により生成した融液相に硫酸塩を反応させる、もしくは溶融した硫酸塩と酸化物を反応させることによって、多様な切削条件において優れた快削性を発揮することができるようになり、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）とが同時に向上し、焼結体の切削性が改善できることを知見した。 In order to achieve the above-mentioned object, the inventors diligently studied various factors on the machinability of the sintered body, particularly the influence of additives. As a result, in the mixed powder, as a machinability improving powder (additive) added together with iron-based powder, alloy powder, and lubricant, sulfate reacts with the melt phase produced by the sintering process or melts. By reacting the sulfate and oxide, excellent free machinability can be exhibited under various cutting conditions, and machinability with a lathe (turnability) and machinability with a drill (drill machinability). It has been found that the machinability of the sintered body can be improved.
この改善機構について、現在までのところ明確になっているわけではないが、低融点酸化物と硫酸塩との反応や、低融点硫酸塩と酸化物との反応においては、混合物粒子の集合状態に応じた焼結反応によって、種々の融点や硬度を持った多種の酸化物と硫酸塩の固溶体が生成され、幅広い溶融温度範囲と硬度とを併せ持つことになるため、焼結体の切削条件に寄らず、快削性を示すことになるのではないかと考えている。 Although this improvement mechanism has not been clarified so far, in the reaction between the low melting point oxide and the sulfate, and the reaction between the low melting point sulfate and the oxide, the mixed particles are brought into an aggregated state. Depending on the sintering reaction, various oxides and sulfate solid solutions with various melting points and hardnesses are generated, and both have a wide melting temperature range and hardness. I think that it will show free-cutting properties.
例えば、融点の低い酸化物または化合物のみを含む場合、焼結体の切削時の発熱が大きくなって融点との差が顕著な高温での切削状態になると、溶融物の粘度が下がりすぎて、工具と焼結体との潤滑効果が低下する傾向が認められた。
また、融点の高い酸化物または化合物のみを含む場合、焼結体の切削時の発熱が小さく融点との差が顕著な低温での切削状態になると、酸化物または化合物は溶融せずに、工具と焼結体との潤滑効果は生じない。
For example, when only the oxide or compound having a low melting point is included, if the heat generation during the cutting of the sintered body is large and the cutting state at a high temperature where the difference from the melting point is remarkable, the viscosity of the melt is too low, There was a tendency for the lubrication effect between the tool and the sintered body to decrease.
In addition, when only an oxide or compound having a high melting point is included, when the sintered body is cut at a low temperature where the heat generation during the cutting of the sintered body is small and the difference from the melting point is significant, the oxide or compound does not melt and the tool does not melt. There is no lubricating effect between the sintered body and the sintered body.
特に、上掲特許文献５に記載された硫酸バリウムは、おどろくべきことに、融点の異なる酸化物、例えば珪酸ナトリウムと併用することで、特許文献５に記載された切削抵抗を減少させる効果のみならず、切り屑の排出促進作用を呈し、優れたドリル切削性を発現することが分かった。なお、このドリル切削性向上効果は、他のアルカリ金属または、アルカリ土類金属の硫酸塩でも認められることを併せて知見した。 In particular, the barium sulfate described in the above-mentioned Patent Document 5 is surprisingly only effective in reducing the cutting resistance described in Patent Document 5 when used in combination with oxides having different melting points, such as sodium silicate. In other words, it has been found that it has an effect of promoting chip discharge and exhibits excellent drill machinability. It was also found that this drill machinability improving effect was also observed with sulfates of other alkali metals or alkaline earth metals.
以上得られた知見から、発明者らは、焼結処理により低温で液相を生成する酸化物と硫酸塩の粉末または低温で液相を生成する硫酸塩と種々の酸化物の粉末を併用することにより、前述した旋削性およびドリル切削性という異なる特性が要求される２つの切削性が同時に向上することを究明した。 From the knowledge obtained above, the inventors use oxide and sulfate powders that generate a liquid phase at low temperatures by sintering treatment, or sulfate and various oxide powders that generate a liquid phase at low temperatures. As a result, it has been clarified that the two machinability requiring different characteristics such as the above-described turning property and drill machinability are simultaneously improved.
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、本発明の要旨構成は次のとおりである。
１．鉄基粉末、合金用粉末、切削性改善用粉末および潤滑剤を混合してなる粉末冶金用混合粉であって、
上記切削性改善用粉末が、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末、酸化マグネシウム（MgO）粉末、シリカ（SiO２）と酸化マグネシウム（MgO）との混合粉末、および珪酸アルカリのうちから選んだ少なくとも１種と、アルカリ金属の硫酸塩粉末およびアルカリ土類金属の硫酸塩粉末のうちから選んだ少なくとも１種とを含み、該切削性改善用粉末の配合量が、上記鉄基粉末、上記合金用粉末および該切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％の範囲である粉末冶金用混合粉。
The present invention has been completed based on such findings and further studies. That is, the gist configuration of the present invention is as follows.
1. A mixed powder for powder metallurgy, which is a mixture of iron-based powder, alloy powder, machinability improving powder and lubricant,
The machinability improving powder is selected from among enstatite powder, talc powder, kaolin powder, mica powder, magnesium oxide (MgO) powder, mixed powder of silica (SiO 2 ) and magnesium oxide (MgO), and alkali silicate. Including at least one selected from at least one selected from an alkali metal sulfate powder and an alkaline earth metal sulfate powder, wherein the blending amount of the powder for improving machinability is the iron-based powder, A mixed powder for powder metallurgy in a range of 0.01 to 1.0% by mass% with respect to the total amount of the alloy powder and the machinability improving powder.
２．前記切削性改善用粉末の配合量に対し、アルカリ金属の硫酸塩粉末および／またはアルカリ土類金属の硫酸塩粉末の配合量が10〜80質量％の範囲である前記１に記載の粉末冶金用混合粉。 2. 2. The powder metallurgy according to 1, wherein the blending amount of the alkali metal sulfate powder and / or the alkaline earth metal sulfate powder is in the range of 10 to 80% by mass with respect to the blending amount of the powder for improving machinability. Mixed powder.
３．前記アルカリ金属の硫酸塩粉末の、アルカリ金属がLi、NaおよびＫのうちから選んだ少なくとも１種であって、前記アルカリ土類金属の硫酸塩粉末の、アルカリ土類金属がMg、Ca、SrおよびBaのうちから選んだ少なくとも１種である前記１または２に記載の粉末冶金用混合粉。 3. In the alkali metal sulfate powder, the alkali metal is at least one selected from Li, Na and K, and the alkaline earth metal sulfate powder in the alkaline earth metal sulfate powder is Mg, Ca, Sr. 3. The mixed powder for powder metallurgy according to 1 or 2, which is at least one selected from Ba and Ba.
４．鉄基粉末、合金用粉末、切削性改善用粉末および潤滑剤を配合したのち、混合して混合粉とする前記１乃至３のいずれか１項に記載の粉末冶金用混合粉の製造方法であって、
上記切削性改善用粉末が、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末、酸化マグネシウム（MgO）粉末、シリカ（SiO２）と酸化マグネシウム（MgO）との混合粉末、および珪酸アルカリのうちから選んだ少なくとも１種と、アルカリ金属の硫酸塩粉末およびアルカリ土類金属の硫酸塩粉末のうちから選んだ少なくとも１種とを含むものとし、
上記切削性改善用粉末の配合量を、上記鉄基粉末、上記合金用粉末および該切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％とし、
さらに、上記混合を、
鉄基粉末と合金用粉末に対し、切削性改善用粉末の一部または全部と潤滑剤の一部を添加して加熱し、該潤滑剤のうち少なくとも１種を溶融させつつ混合したのち、冷却して固化させる一次混合と、
上記切削性改善用粉末および潤滑剤の残り粉末を添加して混合する二次混合と
により行う
粉末冶金用混合粉の製造方法。
4). 4. The method for producing a mixed powder for powder metallurgy according to any one of the above items 1 to 3, wherein an iron-based powder, an alloy powder, a machinability improving powder, and a lubricant are blended and mixed to obtain a mixed powder. And
The machinability improving powder is selected from among enstatite powder, talc powder, kaolin powder, mica powder, magnesium oxide (MgO) powder, mixed powder of silica (SiO 2 ) and magnesium oxide (MgO), and alkali silicate. Including at least one selected and at least one selected from alkali metal sulfate powder and alkaline earth metal sulfate powder;
The blending amount of the powder for improving machinability is 0.01% to 1.0% by mass% with respect to the total amount of the iron-based powder, the alloy powder and the machinability improving powder,
Furthermore, the above mixing
To iron-base powder and alloy powder, a part or all of the machinability improving powder and a part of the lubricant are added and heated, and then mixed while melting at least one of the lubricants, and then cooled. Primary mixing to solidify,
A method for producing a mixed powder for powder metallurgy, which is performed by secondary mixing in which the powder for improving machinability and the remaining powder of a lubricant are added and mixed.
５．前記切削性改善用粉末の配合量に対し、アルカリ金属の硫酸塩粉末および／またはアルカリ土類金属の硫酸塩粉末の含有量を10〜80質量％の範囲とする前記４に記載の粉末冶金用混合粉の製造方法。 5. 5. For powder metallurgy according to 4, wherein the content of the alkali metal sulfate powder and / or the alkaline earth metal sulfate powder is in the range of 10 to 80% by mass with respect to the blending amount of the powder for improving machinability. Manufacturing method of mixed powder.
６．前記アルカリ金属の硫酸塩粉末の、アルカリ金属をLi、NaおよびＫのうちから選んだ少なくとも１種とし、前記アルカリ土類金属の硫酸塩粉末の、アルカリ土類金属をMg、Ca、SrおよびBaのうちから選んだ少なくとも１種とする前記４または５に記載の粉末冶金用混合粉の製造方法。 6). The alkaline metal sulfate powder is at least one selected from Li, Na and K, and the alkaline earth metal sulfate powder is Mg, Ca, Sr and Ba. 6. The method for producing a powder mixture for powder metallurgy according to 4 or 5, wherein at least one selected from among the above is used.
７．前記１乃至３のいずれか１項に記載の粉末冶金用混合粉を用いた鉄基粉末製焼結体。 7). An iron-based powder sintered body using the powder metallurgy mixed powder according to any one of 1 to 3 above.
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する、切削性に優れた焼結体を安価に製造できるので、金属焼結部品の製造コストを顕著に低減するという、産業上格段有利な効果を有する。特に、低速から高速までの広範囲の切削条件で切削が可能なため、ドリルのように中心部と周端部とでその切削速度が大きく変わる加工にその効果を顕著に発揮する。
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るという効果もある。
According to the present invention, it is possible to manufacture a sintered body having excellent turning properties and excellent drill machinability and having excellent machinability at low cost, so that the manufacturing cost of sintered metal parts is significantly reduced. In addition, it has a particularly advantageous industrial effect. In particular, since cutting is possible in a wide range of cutting conditions from low speed to high speed, the effect is remarkably exhibited in processing in which the cutting speed is greatly changed between the central portion and the peripheral end portion like a drill.
Moreover, according to the present invention, there is an effect that at the time of molding, molding can be performed without causing a reduction in the density of the dust and an increase in the output power.
以下、本発明を具体的に説明する。
まず、本発明の粉末冶金用混合粉について説明する。
本発明の粉末冶金用混合粉（または、単に、混合粉という）は、鉄基粉末、合金用粉末、切削性改善用粉末および潤滑剤を混合してなる混合粉である。
Hereinafter, the present invention will be specifically described.
First, the mixed powder for powder metallurgy according to the present invention will be described.
The mixed powder for powder metallurgy (or simply referred to as mixed powder) of the present invention is a mixed powder obtained by mixing an iron-based powder, an alloy powder, a machinability improving powder, and a lubricant.
本発明に用いる鉄基粉末としては、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、および潤滑剤を混合した鉄基粉末混合粉を用いてもよい。 Examples of iron-based powders used in the present invention include pure iron powders such as atomized iron powder and reduced iron powder, pre-alloyed steel powders (alloyed steel powders) pre-alloyed with alloy elements, or alloy elements partially in iron powders. Any of the iron-based powders such as partially diffused alloyed steel powder that has been diffused and alloyed, or hybrid steel powder in which an alloying element is further partially diffused into prealloyed steel powder (fully alloyed steel powder) can be used. Further, as the iron-based powder, an iron-based powder mixed powder obtained by further mixing an alloy powder and a lubricant in addition to the above-described iron-based powder may be used.
他方、本発明に用いる合金用粉末としては、黒鉛粉末や、Cu（銅粉末）粉、Mo粉、Ni粉などの非鉄金属粉末、また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って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、鉄基粉末、合金用粉末および切削性改善用粉末の合計量に対する質量％で、0.1〜10％の範囲が好ましい。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で、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からである。 On the other hand, the alloy powder used in the present invention is exemplified by graphite powder, nonferrous metal powder such as Cu (copper powder) powder, Mo powder, Ni powder, cuprous oxide powder, etc., and desired sintered body characteristics. Select and mix according to. 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 in the range of 0.1 to 10% in mass% with respect to the total amount of the iron-based powder, the alloy powder, and the machinability improving powder according to the desired sintered body strength. This is because if the blending amount of the alloy powder is less than 0.1% by mass, the desired strength of the sintered body cannot be secured, while if it exceeds 10% by mass, the dimensional accuracy of the sintered body decreases.
また、本発明は、切削性改善用粉末として、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末、酸化マグネシウム（MgO）粉末、シリカ（SiO２）と酸化マグネシウム（MgO）との混合粉末、および珪酸アルカリのうちから選んだ少なくとも１種と、アルカリ金属の硫酸塩粉末、およびアルカリ土類金属の硫酸塩粉末のうちから選んだ少なくとも１種を併せて用いるところに特徴がある。 Further, the present invention provides an enstatite powder, a talc powder, a kaolin powder, a mica powder, a magnesium oxide (MgO) powder, a mixed powder of silica (SiO 2 ) and magnesium oxide (MgO) as a machinability improving powder, and It is characterized in that at least one selected from alkali silicates and at least one selected from alkali metal sulfate powder and alkaline earth metal sulfate powder are used in combination.
ここで、少なくともSiO２およびMgOを含む粉末は、焼結時に鉄基粉末表面の酸化鉄層とSiO２、MgOが反応し、融液相を形成する。ここに硫酸塩が存在するとMgO-SiO２-硫酸塩組成物が生成する。粉末混合物を原料とする焼結体では、これらSiO２およびMgOを含む粉末、硫酸塩粉末の存在比率に応じて、種々の組成の固溶体が生じ、それらは組成に応じた種々の融点や硬度を有すると考えられる。 Here, the powder containing at least SiO 2 and MgO are iron oxide layer and the SiO 2 of the iron-based powder surface during sintering, MgO is reacted to form the melt phase. When sulfate is present here, an MgO—SiO 2 -sulfate composition is formed. In a sintered body using a powder mixture as a raw material, solid solutions having various compositions are generated depending on the abundance ratios of the powder containing SiO 2 and MgO and the sulfate powder, and they have various melting points and hardness depending on the composition. It is thought to have.
また珪酸アルカリを含む場合にも同様の現象が起こり、たとえば珪酸ナトリウムの場合にはNaO-SiO２-硫酸塩組成物が生成する。これら珪酸ナトリウム粉末、硫酸塩粉末の存在比率に応じて、種々の組成の固溶体が生じ、それらは組成に応じた種々の融点や硬度を有すると考えられる。
従って、本発明に従う鉄基粉末製焼結体は、これら種々の融点を有する固溶体を備えることによって、切削時の発熱により上昇する焼結体温度に応じた融点を有する固溶体が存在するので、工具と焼結体との潤滑効果が、切削状態によらず安定して得られるのである。また、硬質のSi酸化物は、硫酸塩の化合物を作ることによって組織が軟化するため、切り屑が微細化し、特にドリル切削の場合には、切り屑の排除性が大幅に向上して、ドリル切削性改善効果に大きく貢献する。
The same phenomenon occurs when an alkali silicate is contained. For example, in the case of sodium silicate, a NaO—SiO 2 -sulfate composition is formed. Depending on the abundance ratio of these sodium silicate powder and sulfate powder, solid solutions having various compositions are formed, and they are considered to have various melting points and hardness depending on the composition.
Therefore, the sintered body made of iron-based powder according to the present invention has a solid solution having a melting point corresponding to the sintered body temperature that rises due to heat generated during cutting by providing the solid solution having these various melting points. Therefore, the lubricating effect between the sintered body and the sintered body can be stably obtained regardless of the cutting state. In addition, the hard Si oxide makes the structure soft by making a sulfate compound, so the chips become finer, especially in the case of drill cutting. This greatly contributes to the improvement of machinability.
切削性改善用粉末として混合粉に添加する、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末等の鉱物はいずれも、少なくともSi、Mg、Ｏ元素（SiO２、MgO）を含有する金属化合物である。このように、Si、Mg、Ｏを含有する化合物である粉末は、上述するように、いずれも、混合粉を成形した圧粉体を焼結する際に、硫酸塩と反応して、種々の組成の固溶体が生じ、それらは組成に応じた種々の融点や硬度を有する。
また、珪酸アルカリは、珪酸ナトリウムや珪酸カリウムなどが例示されるが、これら粉末は、いずれも、混合粉を成形した圧粉体を焼結する際に、硫酸塩と反応して、種々の組成の固溶体が生じ、それらは組成に応じた種々の融点や硬度を有する。
Minerals such as enstatite powder, talc powder, kaolin powder, mica powder, etc. added to the mixed powder as a machinability improving powder are metal compounds containing at least Si, Mg, and O elements (SiO 2 , MgO). is there. Thus, as described above, the powder that is a compound containing Si, Mg, and O reacts with sulfate when sintering the green compact formed from the mixed powder, Solid solutions of composition are produced, which have various melting points and hardness depending on the composition.
Examples of the alkali silicate include sodium silicate and potassium silicate. These powders react with sulfate when sintering the green compact formed from the mixed powder, and have various compositions. These solid solutions are produced and have various melting points and hardness depending on the composition.
本発明において、切削性改善用粉末に含まれるアルカリ金属の硫酸塩粉末、およびアルカリ土類金属の硫酸塩粉末は、焼結処理により生成した融液相と反応するもの、または溶融して酸化物と反応するもののいずれかであればよいが、具体的には、硫酸リチウム、硫酸ナトリウム、硫酸カリウム、硫酸マグネシウム、硫酸カルシウム、硫酸ストロンチウムおよび硫酸バリウムなどが挙げられる。これら粉末は、いずれも、混合粉を成形した圧粉体を焼結する際に、SiO2および／またはMgOを含む粉末から生成する融液相や珪酸アルカリと反応して、種々の組成の固溶体が生じ、それらは組成に応じ種々の融点や硬度を有するからである。 In the present invention, the alkali metal sulfate powder and alkaline earth metal sulfate powder contained in the powder for improving machinability are those that react with the melt phase produced by the sintering treatment, or are melted and oxides. Specific examples include lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, and barium sulfate. All of these powders react with the melt phase and alkali silicate generated from the powder containing SiO 2 and / or MgO when sintering the green compact formed from the mixed powder, so that solid solutions of various compositions This is because they have various melting points and hardness depending on the composition.
以上述べた切削性改善用粉末に対し、アルカリ金属の硫酸塩粉末および／またはアルカリ土類金属の硫酸塩粉末の配合量は、切削性改善用粉末の合計量に対する質量％で、10〜80％の範囲とすることが好ましい。配合量が10質量％未満では、上記した効果が期待できない一方で、80質量％を超える配合では高速での切削性改善効果が低下するからである。 The blending amount of the alkali metal sulfate powder and / or alkaline earth metal sulfate powder is 10% to 80% by mass with respect to the total amount of the machinability improving powder with respect to the machinability improving powder described above. It is preferable to set it as the range. This is because, if the blending amount is less than 10% by mass, the above-described effects cannot be expected, whereas if the blending amount exceeds 80% by mass, the effect of improving the machinability at high speed decreases.
また、本発明に従う混合粉の切削性改善用粉末の配合量は、鉄基粉末、合金用粉末および切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％の範囲とする必要がある。配合量が、0.01質量％未満では、切削性改善効果が不十分となる一方で、1.0質量％を超えて配合すると、圧粉体密度が低下し、その成形体を焼結して得た焼結体の機械的強度が低下するからである。このため、混合粉における切削性改善用粉末の配合量は、鉄基粉末、合金用粉末および切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％の範囲に限定する。 Further, the blending amount of the powder for improving machinability of the mixed powder according to the present invention should be in the range of 0.01 to 1.0% by mass% with respect to the total amount of the iron-based powder, the alloy powder and the machinability improving powder. . When the blending amount is less than 0.01% by mass, the effect of improving the machinability is insufficient. On the other hand, when the blending amount exceeds 1.0% by mass, the green compact density is lowered, and the sintered body obtained by sintering the compact is obtained. This is because the mechanical strength of the bonded body is lowered. For this reason, the blending amount of the powder for improving machinability in the mixed powder is limited to the range of 0.01 to 1.0% in terms of mass% with respect to the total amount of the iron-based powder, the alloy powder and the machinability improving powder.
本発明に従う混合粉には、上記した鉄基粉末、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、いわゆる外添加量として、金属粉末、合金用粉末、切削性改善用粉末の合計量100質量％に対し、0.1〜1.0質量％−外割とすることが好ましい。潤滑剤の配合量が、0.1質量％−外割に満たないと、金型との摩擦が増加して抜き出し力が増大して金型寿命が低下する一方で、1.0質量％−外割を超えて多量となると、成形密度が低下して焼結体密度が低くなってしまうからである。
なお、本発明に用いられる上記した粉末や、本発明の粉末冶金用混合粉は、いずれも、工業的に許容される種類や量の不可避的不純物の混入は問題ない。
In addition to the iron-based powder, the alloy powder, and the machinability improving powder, an appropriate amount of lubricant is blended in the mixed powder according to 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 as a so-called external addition amount, 0.1 to 1.0% by mass-external split with respect to 100% by mass of the total amount of metal powder, alloy powder and machinability improving powder. It is preferable that If the blending amount of the lubricant is less than 0.1% by mass-external ratio, the friction with the mold increases, the extraction force increases, and the mold life decreases, while 1.0% by mass exceeds the external ratio. This is because if the amount is too large, the molding density decreases and the sintered body density decreases.
In addition, the above-described powder used in the present invention and the mixed powder for powder metallurgy of the present invention have no problem in mixing unavoidable types and amounts of industrially acceptable types.
つぎに、本発明に従う混合粉を得るのに好ましい製造方法について説明する。
鉄基粉末に対して、上記した種類や配合量の粉末からなる合金用粉末、および上記した種類や配合量の粉末からなる切削性改善用粉末、さらには潤滑剤を、それぞれ所定量添加（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。上記した切削性改善用粉末は、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）を行ったのち、残部（二次混合材）を配合して混合（二次混合）することもできる。なお、潤滑剤は、二回に分けて添加（配合）することが好ましい。
なお、鉄基粉末の一部または全部に対し、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結合材によって表面に固着させる偏析防止処理を施した鉄基粉末を用いても良い。ここで、偏析防止処理としては、特許第3004800号公報に記載の偏析防止処理を用いることができる。
Next, a preferable production method for obtaining the mixed powder according to the present invention will be described.
Predetermined amounts of each of the above-mentioned types and blending amounts of powder for alloys, powders for improving machinability composed of powders of the above-mentioned types and blending amounts, and lubricants are added to the iron-based powder. It is desirable to use a generally known mixer to mix once or twice or more to obtain mixed powder (iron-based mixed powder). The above-mentioned machinability improving powder does not necessarily need to be mixed all at once. After mixing and mixing only a part (primary mixing), the remaining part (secondary mixture) is mixed and mixed ( (Secondary mixing). The lubricant is preferably added (mixed) in two steps.
Note that an iron-base powder that has been subjected to segregation prevention treatment in which part or all of the powder for alloying and / or the powder for improving machinability is fixed to the surface with a binder may be used for part or all of the iron-based powder. good. Here, as the segregation prevention treatment, the segregation prevention treatment described in Japanese Patent No. 3004800 can be used.
本発明では、混合粉に配合した種々の潤滑剤の融点の最低温度以上に加熱することで、前記潤滑剤のうち少なくとも１種類の潤滑剤を溶融させつつ一次混合したのち、冷却して固化させ、ついで、切削性改善用粉末と潤滑剤の残り粉末からなる二次混合材を添加して二次混合をすることが好ましい。 In the present invention, at least one lubricant among the lubricants is first mixed while being melted by heating to a temperature equal to or higher than the minimum melting point of various lubricants blended in the mixed powder, and then cooled and solidified. Then, it is preferable to perform secondary mixing by adding a secondary mixed material composed of the powder for improving machinability and the remaining powder of the lubricant.
また、混合手段としては、とくに制限はなく、従来公知の混合機の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得られる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。
まず、上記した方法で製造された本発明に従う粉末冶金用混合粉を、金型に充填して圧縮成形し、成形体とする。成形方法は、プレス等の公知の成形方法がいずれも好適に使用できる。本発明に従う粉末冶金用混合粉を用いることによって、成形圧力を294MPa以上と高圧にすることができ、さらに常温で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したりすることが好ましい。
Below, the preferable manufacturing method of the sintered compact using the mixed powder for powder metallurgy obtained with an above-described manufacturing method is demonstrated.
First, the mixed powder for powder metallurgy according to the present invention manufactured by the method described above is filled into a mold and compression molded to obtain a molded body. As the molding method, any known molding method such as a press can be suitably used. By using the mixed powder for powder metallurgy according to the present invention, the molding pressure can be increased to 294 MPa or higher, and further molding can be performed at room temperature. In order to ensure 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、圧縮成形を、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、本発明の粉末冶金用混合粉は、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。 Further, when the compression 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 for powder metallurgy of the present invention is excellent in compressibility, and thus exhibits excellent moldability even at a temperature of less than 150 ° C., and there is a concern about deterioration due to oxidation when the temperature exceeds 150 ° C.
上記成形加工により得られた成形体は、ついで焼結処理を施されて、本発明に従う鉄基粉末製焼結体となる。焼結処理の温度は、金属粉末の融点の約70％の温度で行うことが望ましい。
鉄基粉末の場合、焼結処理の温度は、1000℃以上であって、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からである。一方、焼結処理の温度が1300℃を超えて高温になると、焼結中に異常粒成長が起こって、焼結体強度が低下しやすくなるので好ましくない。
The molded body obtained by the above-described molding process is then subjected to a sintering treatment to become an iron-based powder sintered body according to the present invention. The temperature of the sintering treatment is desirably about 70% of the melting point of the metal powder.
In the case of iron-based powder, the sintering temperature is 1000 ° C. or higher, preferably 1300 ° C. or lower. This is because if the sintering temperature is less than 1000 ° C., it becomes difficult to obtain a sintered body having a desired density. On the other hand, if the temperature of the sintering process exceeds 1300 ° C. and becomes high, abnormal grain growth occurs during sintering, and the strength of the sintered body tends to decrease, which is not preferable.
上記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ガス雰囲気、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。
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。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。
The sintering atmosphere is an inert gas 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
After the sintering treatment, heat treatment such as gas carburizing heat treatment or carbonitriding treatment is 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、実施例により、本発明をさらに詳細に説明するが、本発明は、以下の例に何ら限定されるものではない。
鉄基粉末として、表１に示す鉄基粉末（いずれも平均粒径：約80μm）を使用した。なお、以下記載の平均粒径は、レーザ回折法を利用して求めたものである。
ここに、使用した鉄基粉末は、表１に示したとおり、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）、および、合金元素として、Moを予合金化した完全合金化鋼粉にさらにMoを部分拡散合金化した鋼粉（ハイブリッド型合金鋼粉）（Ｇ）である。
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following examples at all.
As the iron-based powder, the iron-based powder shown in Table 1 (both average particle size: about 80 μm) was used. In addition, the average particle diameter described below is obtained using a laser diffraction method.
As shown in Table 1, the iron-based powder used here is atomized pure iron powder (A), reduced pure iron powder (B), and partial diffusion in which Cu is partially diffused and alloyed on the surface of the iron powder as an alloying element. Alloyed steel powder (C), partially diffused alloyed steel powder (D) in which Ni, Cu, and Mo are partially diffused and alloyed on the surface of iron powder, and prealloyed in which Ni and Mo are prealloyed as alloy elements Steel powder (fully alloyed steel powder) (E), pre-alloyed steel powder (fully alloyed steel powder) (F) pre-alloyed with Mo as alloy element, and Mo pre-alloyed with alloy element This is a steel powder (hybrid alloy steel powder) (G) obtained by partial diffusion alloying Mo with the fully alloyed steel powder.
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に示した種類、配合量の切削性改善用粉末と、さらに、表２に示した種類、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、一次混合を行った。なお、一次混合では、混合しながら140℃に加熱した後、60℃以下に冷却した。また、合金用粉末として配合した天然黒鉛粉は平均粒径：５μmの粉末とし、銅粉は平均粒径：20μmの粉末とした。 The above-described iron-based powder includes the types and amounts of alloy powders shown in Table 2, the types and amounts shown in Table 2, and the machinability improving powders shown in Table 2, and the types and amounts shown in Table 2. A lubricant was blended and primary mixing was performed using a high-speed bottom stirring mixer. In primary mixing, the mixture was heated to 140 ° C. while mixing and then cooled to 60 ° C. or less. The natural graphite powder blended as an 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 20 μm.
一次混合したのち、さらに表２に示した種類、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1000rpm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。なお、切削性改善用粉末は、一次混合と二次混合時の二回に分けて配合した。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、外添加とし、鉄基粉末、合金用粉末、切削性改善用粉末の合計量100質量％に対する質量％−外割で表示した。
以上の工程を経て、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。
なお、比較例として、表２に示した種類、配合量で、鉄基粉末、合金用粉末、潤滑剤を配合し、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。
After the primary mixing, further mix the secondary mixing material consisting of the types and blending amounts of powders for improving machinability and lubricants shown in Table 2, and the mixing speed is 1000 rpm. Was done. After the secondary mixing, the mixed powder was discharged from the mixer. In addition, the machinability improving powder was blended in two steps during primary mixing and secondary mixing. The compounding amount of the machinability improving powder is expressed in mass% with respect to the total amount of the iron-based powder, alloy powder, and machinability improving powder, and the compounding amount of the lubricant is externally added. It was expressed in terms of mass% -extracent to the total amount of powder and machinability improving powder of 100 mass%.
Through the above steps, 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.
As a comparative example, iron-based powder, alloy powder, and lubricant were blended in the types and blending amounts shown in Table 2, and mixed at room temperature using a V-type container rotary mixer. Obtained.
引続き、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）に充填し、加圧力：590MPaで圧縮成形し、成形体を得た。その得られた成形体に、RXガス雰囲気中で、1130℃×20minの焼結処理を施して、焼結体を得た。
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。
Subsequently, the obtained mixed powder was filled into a mold (two types for lathe cutting test and drill cutting test) and compression molded at a pressure of 590 MPa to obtain a molded body. The obtained molded body was subjected to a sintering treatment at 1130 ° C. for 20 minutes in an RX gas atmosphere to obtain a sintered body.
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、旋盤を利用して切削した。切削条件は、サーメット製旋盤用切削工具を用いて、切削速度：100m/minおよび200m／min、送り量：0.1mm／回、切込み深さ：0.5mm、切削距離：1000mとし、試験後、切削工具の逃げ面の摩耗幅を測定した。ここで工具寿命を概ね0.25ｍｍの磨耗量と規定し、切削距離1000m未満でこの工具寿命に達した場合は、1000ｍ未達と記載した。従って、切削工具の逃げ面の摩耗幅が小さいほど、焼結体の切削性が優れていると評価される。
(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: cutting speed: 100m / min and 200m / min, feed rate: 0.1mm / turn, depth of cut: 0.5mm, cutting distance: 1000m, using a cermet lathe cutting tool. The wear width of the flank of the tool was measured. Here, the tool life is defined as an amount of wear of approximately 0.25 mm, and when the tool life is reached at a cutting distance of less than 1000 m, it is described as less than 1000 m. Therefore, it is evaluated that the smaller the wear width of the flank of the cutting tool, the better the machinability of the sintered body.
（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：2.6mm）で、回転数：5,000rpm、送り速度：750mm／minの条件で貫通穴を穿孔し、その際、切削動力計を用い、ドリル切削時の切削抵抗としてスラスト成分を測定した。スラスト成分が小さいほど、焼結体の切削性が優れていると評価される。
得られた結果を、表３にそれぞれ示す。
(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: 2.6 mm), rotating speed: 5,000 rpm, feed rate: 750 mm / A through hole was drilled under the condition of min. At that time, a thrust component was measured as a cutting resistance at the time of drill cutting using a cutting dynamometer. It is evaluated that the smaller the thrust component, the better the machinability of the sintered body.
The obtained results are shown in Table 3, respectively.
表３に示したとおり、本発明に従う発明例はいずれも、切削工具逃げ面の摩耗幅が小さい結果を示しているので、旋盤切削性に優れていることが分かる。加えて、ドリル穿孔時のスラスト成分が低い値を示しているので、ドリル切削性にも優れた焼結体となっていることが分かる。一方、本発明の範囲を外れる比較例は、特に、ドリル切削性に劣った結果となっていた。 As shown in Table 3, since all of the inventive examples according to the present invention show the result that the wear width of the cutting tool flank is small, it is understood that the lathe machinability is excellent. In addition, since the thrust component at the time of drilling shows a low value, it can be seen that the sintered body is excellent in drill machinability. On the other hand, the comparative example which deviates from the range of the present invention has a particularly poor drill cutting performance.
Claims (7)
上記切削性改善用粉末が、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末、酸化マグネシウム（MgO）粉末、シリカ（SiO２）と酸化マグネシウム（MgO）との混合粉末、および珪酸アルカリのうちから選んだ少なくとも１種と、アルカリ金属の硫酸塩粉末およびアルカリ土類金属の硫酸塩粉末のうちから選んだ少なくとも１種とを含み、該切削性改善用粉末の配合量が、上記鉄基粉末、上記合金用粉末および該切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％の範囲である粉末冶金用混合粉。 A mixed powder for powder metallurgy, which is a mixture of iron-based powder, alloy powder, machinability improving powder and lubricant,
The machinability improving powder is selected from among enstatite powder, talc powder, kaolin powder, mica powder, magnesium oxide (MgO) powder, mixed powder of silica (SiO 2 ) and magnesium oxide (MgO), and alkali silicate. Including at least one selected from at least one selected from an alkali metal sulfate powder and an alkaline earth metal sulfate powder, wherein the blending amount of the powder for improving machinability is the iron-based powder, A mixed powder for powder metallurgy in a range of 0.01 to 1.0% by mass% with respect to the total amount of the alloy powder and the machinability improving powder.
上記切削性改善用粉末が、エンスタタイト粉末、タルク粉末、カオリン粉末、マイカ粉末、酸化マグネシウム（MgO）粉末、シリカ（SiO２）と酸化マグネシウム（MgO）との混合粉末、および珪酸アルカリのうちから選んだ少なくとも１種と、アルカリ金属の硫酸塩粉末およびアルカリ土類金属の硫酸塩粉末のうちから選んだ少なくとも１種とを含むものとし、
上記切削性改善用粉末の配合量を、上記鉄基粉末、上記合金用粉末および該切削性改善用粉末の合計量に対する質量％で、0.01〜1.0％とし、
さらに、上記混合を、
鉄基粉末と合金用粉末に対し、切削性改善用粉末の一部または全部と潤滑剤の一部とを添加して加熱し、該潤滑剤のうち少なくとも１種を溶融させつつ混合したのち、冷却して固化させる一次混合と、
上記切削性改善用粉末および潤滑剤の残り粉末を添加して混合する二次混合と
により行う
粉末冶金用混合粉の製造方法。 The method for producing a mixed powder for powder metallurgy according to any one of claims 1 to 3, wherein an iron-based powder, an alloy powder, a machinability improving powder and a lubricant are blended and mixed to form a mixed powder. There,
The machinability improving powder is selected from among enstatite powder, talc powder, kaolin powder, mica powder, magnesium oxide (MgO) powder, mixed powder of silica (SiO 2 ) and magnesium oxide (MgO), and alkali silicate. Including at least one selected and at least one selected from alkali metal sulfate powder and alkaline earth metal sulfate powder;
The blending amount of the powder for improving machinability is 0.01% to 1.0% by mass% with respect to the total amount of the iron-based powder, the alloy powder and the machinability improving powder,
Furthermore, the above mixing
After adding and heating a part or all of the machinability improving powder and a part of the lubricant to the iron base powder and the alloy powder, after mixing at least one of the lubricants while melting, Primary mixing to cool and solidify,
A method for producing a mixed powder for powder metallurgy, which is performed by secondary mixing in which the powder for improving machinability and the remaining powder of a lubricant are added and mixed.
A sintered body made of iron-based powder using the mixed powder for powder metallurgy according to any one of claims 1 to 3.
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