JP4677551B2 - Sintering method and apparatus - Google Patents

Sintering method and apparatus Download PDF

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JP4677551B2
JP4677551B2 JP2003300990A JP2003300990A JP4677551B2 JP 4677551 B2 JP4677551 B2 JP 4677551B2 JP 2003300990 A JP2003300990 A JP 2003300990A JP 2003300990 A JP2003300990 A JP 2003300990A JP 4677551 B2 JP4677551 B2 JP 4677551B2
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diameter portion
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cylinder
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stepped
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周二 多田
正明 孫
等 橋本
利彦 阿部
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National Institute of Advanced Industrial Science and Technology AIST
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本発明は、金属やセラミックス等に対する直接通電加圧焼結において、粉体を加圧する各パンチ及び又は成形空間を有するシリンダに加える荷重を独立に制御することにより、断面形状が一様でない、すなわち長手方向に径が変化する部品を緻密に焼結する方法及び装置を提供するものである。   In the present invention, in direct current pressure sintering for metal, ceramics, etc., the cross-sectional shape is not uniform by independently controlling the load applied to each punch for pressing the powder and / or the cylinder having the molding space. A method and apparatus for densely sintering a part whose diameter changes in the longitudinal direction is provided.

直接通電による加圧焼結法によれば、被焼結材をきわめて高速に昇温できるため、雰囲気加熱による従来の焼結手法と比較して製造時間の大幅な短縮が可能である。一般に、従来の直接通電による加熱焼結法は、被焼結体の軸方向の両端に通電加熱用の電極を配置して加圧すると同時に加熱する手法が取られている。   According to the pressure sintering method by direct energization, the material to be sintered can be heated at a very high speed, so that the manufacturing time can be greatly reduced as compared with the conventional sintering method by atmospheric heating. In general, the conventional heating and sintering method by direct energization employs a technique in which electrodes for energization heating are arranged at both ends in the axial direction of a sintered body and are simultaneously heated.

しかしながら、このような直接通電加圧焼結法によって段付き部材など断面形状が変化する部品を製造する場合、径の大小にかかわらず被焼結材料には同じ荷重がかかってしまうため、細径部の圧力が太径部よりも大きくなり、その結果として、焼結中に細径部に充てんした材料が太径部へ移動して、所望の形状が得られないという問題がある。   However, when manufacturing a part whose cross-sectional shape changes, such as a stepped member, by the direct current pressure sintering method, the same load is applied to the material to be sintered regardless of the size of the diameter. As a result, there is a problem that the material filled in the small diameter portion moves to the large diameter portion during sintering and a desired shape cannot be obtained.

また、このような部品では、通電経路に垂直な断面の面積が一定とならないため、電気抵抗の差による発熱量の変化により均一な焼結体が得られないという難点も抱えている。したがって、段付きやテーパ部を有するなど、断面形状が変化する部品を直接通電による加圧焼結法によって製造することはきわめて困難である。   Further, in such a component, since the area of the cross section perpendicular to the energization path is not constant, there is a problem that a uniform sintered body cannot be obtained due to a change in the amount of heat generated due to a difference in electric resistance. Therefore, it is extremely difficult to manufacture a part whose cross-sectional shape changes, such as having a step or a taper portion, by a pressure sintering method by direct energization.

このようなことから、従来の被焼結体の軸方向の両端に通電加熱用の電極を配置して加圧する替わりに、被焼結体の側面に電極を配置し加熱する方法を、本発明者らが提案した（例えば、特許文献１および２参照）。
しかるに、この方法は、断面形状が一様でない被焼結材料の電気抵抗の変化に対し、通電電流を部位ごとに調整して全体を均一な温度で焼結することを主眼としたものであり、この目的のためには極めて有効である。しかし、圧力差による被焼結材料の形状変化には対応できないという問題があった。
特願２００３−０４６６６１号 特願２００３−０４６６９０号 Therefore, instead of placing and heating the electrodes for current heating at both ends in the axial direction of the conventional sintered body, the method of arranging and heating the electrodes on the side surfaces of the sintered body is described in the present invention. (See, for example, Patent Documents 1 and 2).
However, this method is mainly intended to sinter the whole at a uniform temperature by adjusting the energization current for each part against the change in electrical resistance of the material to be sintered whose cross-sectional shape is not uniform. It is extremely effective for this purpose. However, there is a problem that it cannot cope with a change in the shape of the material to be sintered due to a pressure difference.
Japanese Patent Application No. 2003-046661 Japanese Patent Application No. 2003-046690

本発明は、かかる事情に鑑み、断面形状が一様でない、すなわち長手方向に径が変化する焼結体であっても、所望の形状に合わせた精密成形が可能であり、また焼結体の品質が均一であって、さらに焼結性に優れた焼結方法及び装置を提供するものである。   In view of such circumstances, the present invention is capable of precision molding in accordance with a desired shape even if the cross-sectional shape is not uniform, that is, a sintered body whose diameter changes in the longitudinal direction. A sintering method and apparatus having uniform quality and excellent sinterability are provided.

本発明は、断面形状が一様でない焼結体を得るために研究を重ねた結果、特許文献１〜２に提案された方法をもとに、被焼結材料を加圧するパンチ両端及び又はラムに加える荷重を独立に制御し、被焼結材料にかかる圧力を一定にしながら焼結を行うことによって、この目的を達成し得ることを見いだした。   As a result of repeated research to obtain a sintered body having a non-uniform cross-sectional shape, the present invention is based on the methods proposed in Patent Documents 1 and 2, and both ends of a punch and / or a ram that pressurizes a material to be sintered. It has been found that this object can be achieved by independently controlling the load applied to the material and performing the sintering while keeping the pressure applied to the material to be sintered constant.

すなわち、本発明は、上記知見に基づき
１）筒状の太径部と細径部の空間を有するシリンダの型内で、当該型となるシリンダの側面に配置した電極により原料粉末を直接通電して、長手方向に径が変化する部品を加圧焼結する方法において、原料粉末の上下の加圧用パンチ及び筒状の太径部と細径部の空間を形成するシリンダ加圧用のラムに加える荷重を、それぞれ独立に制御することを特徴とする焼結方法
２）筒状の空間を有する型内に配置した焼結原料粉末を型の一端部又は両端部から加圧することを特徴とする上記１）記載の焼結方法
３）被焼結材料の断面積が一様でない場合でも、それに加わる圧力が一定となるように制御することを特徴とする上記１）又は２）記載の焼結方法
４）１又は複数のラムを用いて加圧することを特徴とする上記１）〜３）のいずれかに記載の焼結方法
５）筒状の太径部と細径部の空間を有する型内で、当該型となるシリンダの側面に配置した電極により原料粉末を直接通電して、長手方向に径が変化する部品を加圧焼結する方法において、原料粉末の上下の加圧用パンチ及び筒状の太径部と細径部の空間を形成するシリンダを少なくとも１個の加圧用ラムを用いて加圧する際に、最初に上下のパンチを加圧し、引き続いてシリンダを加圧し、さらに上下のパンチを加圧することにより、パンチとシリンダの加圧を経時的に、上下のパンチとシリンダの加圧をそれぞれ独立に加圧制御することを特徴とする焼結方法
６）シリンダと加圧用ラム間にスペーサを設け、そのスペーサの厚さを調節することによりパンチとシリンダの加圧のストローク差を制御することを特徴とする上記５）記載の焼結方法
７）シリンダと加圧用ラム間にスペーサを設け、最初にパンチを加圧し、次にスペーサを介してシリンダの加圧を開始し、最後にスペーサを除去してパンチのみによる加圧を行うことを特徴とする上記５）又は６）記載の焼結方法、を提供する。 In other words, the present invention is based on the above findings. 1) In the cylinder mold having a cylindrical large diameter portion and a small diameter portion space, the raw material powder is directly energized by the electrode disposed on the side surface of the cylinder to be the mold. In addition, in the method of pressure-sintering a part whose diameter changes in the longitudinal direction, it is added to the upper and lower pressurizing punches of the raw material powder and the cylinder pressurizing ram that forms the space between the cylindrical large diameter part and the small diameter part Sintering method characterized in that the load is controlled independently 2) The sintering raw material powder placed in a mold having a cylindrical space is pressed from one or both ends of the mold 1) Sintering method according to 1) 3) Sintering method according to 1) or 2), wherein the pressure applied to the material to be sintered is controlled to be constant even when the cross-sectional area of the material to be sintered is not uniform. 4) It is characterized by applying pressure using one or more rams. Above 1) in a mold having a sintering method 5) a cylindrical large-diameter portion and the space of the small-diameter portion of any one of to 3), the raw material powder by the electrode disposed on the side surface of the cylinder to become such type that In the method of pressure-sintering a part whose diameter changes in the longitudinal direction by directly energizing, at least a pressing punch above and below the raw material powder and a cylinder that forms a space between the cylindrical large diameter part and the small diameter part When pressurizing with one pressurizing ram, the upper and lower punches are first pressed, the cylinder is subsequently pressed, and the upper and lower punches are further pressed. The sintering method is characterized in that the pressurization of the upper and lower punches and the cylinder is controlled independently of each other. 6) A spacer is provided between the cylinder and the pressurization ram, and the thickness of the spacer is adjusted. Cylinder pressure stroke 5) The sintering method according to 5) above, wherein a spacer is provided between the cylinder and the pressurization ram, the punch is first pressed, and then pressurization of the cylinder is started via the spacer. Finally, the sintering method according to 5) or 6) above, wherein the spacer is removed and pressurization is performed only with a punch.

本発明は、また
８）筒状の太径部と細径部の空間を有する型内で、当該型となるシリンダの側面に配置した電極により原料粉末を直接通電して、長手方向に径が変化する部品を加圧焼結する装置において、原料粉末の上下の加圧用パンチ、筒状の太径部と細径部の空間を形成するシリンダ及びこれらのパンチ及びシリンダを、それぞれ独立に加圧制御できる複数の加圧用ラムを備えていることを特徴とする焼結装置
９）筒状の太径部と細径部の空間を有する型内で、当該型となるシリンダの側面に配置した電極により原料粉末を直接通電して、長手方向に径が変化する部品を加圧焼結する装置において、原料粉末の上下の加圧用パンチ、筒状の太径部と細径部の空間を形成するシリンダ及びこれらのパンチ及びシリンダを、最初にパンチを加圧し、引き続いてシリンダを加圧し、さらにパンチを加圧する加圧用ラムを備えていることを特徴とする焼結装置
１０）シリンダと加圧用ラム間に、パンチとシリンダの加圧のストローク差を調節するスペーサを備えていることを特徴とする上記９）記載の焼結装置、を提供する。 In the present invention, 8) In a mold having a cylindrical large-diameter portion and a small-diameter portion, the raw material powder is directly energized by an electrode disposed on the side surface of the cylinder to be the mold, and the diameter is increased in the longitudinal direction. In an apparatus that pressurizes and sinters changing parts, pressurizing punches above and below the raw material powder, a cylinder forming a space between a cylindrical large diameter part and a small diameter part, and these punches and cylinders are independently pressurized. Sintering apparatus comprising a plurality of pressurizing rams that can be controlled 9) An electrode disposed on a side surface of a cylinder that becomes a mold in a mold having a cylindrical large diameter portion and a small diameter space In the apparatus that directly energizes the raw material powder and pressurizes and sinters the parts whose diameter changes in the longitudinal direction, the upper and lower pressurizing punches of the raw material powder, the space between the cylindrical large diameter portion and the small diameter portion are formed. Cylinders and their punches and cylinders are And, between the subsequent cylinder is pressurized, further sintering apparatus 10, characterized in that it comprises a pressurization ram for pressing a punch) cylinder and pressing ram, adjust the stroke difference between the punch and the cylinder of the pressure There is provided a sintering apparatus as described in 9) above, characterized by comprising a spacer.

本発明は、直接通電による加圧焼結法の弱点であった段付き部材など断面形状が一様ではない部品、すなわち長手方向に径が変化する部品の製造において、優れた効果を発揮する。すなわち、高融点材料や機械加工がきわめて困難な硬い材料でも、段付き等の形状を備えた部品への緻密成形が可能になるものである。
直接通電加圧焼結法は、投入するエネルギーが少なく効率的であり、また作業に要する時間が短縮されるという優れた成形方法であるが、本発明はさらに形状的な適用範囲を拡大できるという点で、産業上極めて有効である。 INDUSTRIAL APPLICABILITY The present invention exhibits an excellent effect in the manufacture of a part having a non-uniform cross-sectional shape, such as a stepped member, which is a weak point of the pressure sintering method by direct energization, that is, a part whose diameter changes in the longitudinal direction. That is, even a high melting point material or a hard material that is extremely difficult to machine can be densely formed into a part having a stepped shape.
The direct-current pressure-sintering method is an efficient molding method that requires less energy and is efficient and reduces the time required for work, but the present invention can further expand the scope of application of the shape. In this respect, it is extremely effective in the industry.

本発明においては、公知の通電加圧焼結法及上記の本発明者らによる特許文献１〜２に記載した発明を基に、従来は被焼結材料を全体的に一様荷重で加圧していたものを、被焼結材料にかかる圧力が断面積の大小にかかわらず一定となるよう、材料の両端から加える荷重をそれぞれ独立して制御することによって、焼結品質が良好な、段付き部品などの断面形状が一様でない焼結部材を製造する方法を開発した。   In the present invention, based on the known current pressure sintering method and the inventions described in Patent Documents 1 and 2 by the above-described inventors, conventionally, the material to be sintered is generally pressed with a uniform load. Stepped with good sintering quality by independently controlling the load applied from both ends of the material so that the pressure applied to the material to be sintered is constant regardless of the cross-sectional area We have developed a method for manufacturing sintered parts with non-uniform cross-sectional shapes such as parts.

段付き部品を焼結する場合の一例を図１沿って説明する。図１は原料粉末両端にかかる圧力をそれぞれ独立に制御しながら、移動式部分焼結等を行うことにより、段付き部品など断面形状が一様でない焼結体を良好に製造する方法に使用する装置の一例を示す概略説明図である。   An example in the case of sintering a stepped part is demonstrated along FIG. FIG. 1 is used in a method for satisfactorily producing a sintered body having a non-uniform cross-sectional shape such as a stepped part by performing movable partial sintering while independently controlling the pressure applied to both ends of the raw material powder. It is a schematic explanatory drawing which shows an example of an apparatus.

この図１に示すように、まず、原料粉末１をシリンダ２内に充填する。充填された原料粉末１は、型の内部でパンチＡ３およびパンチＢ４により両端から加圧される。このとき、原料粉末１において、細径側にかかる圧力と太径側にかかる圧力とが同じになるよう、シリンダ２を押圧する加圧ラムＡ５と加圧ラムＢ６とに加える圧力を制御する。   As shown in FIG. 1, first, raw material powder 1 is filled in a cylinder 2. The filled raw material powder 1 is pressed from both ends by a punch A3 and a punch B4 inside the mold. At this time, in the raw material powder 1, the pressure applied to the pressure ram A5 and the pressure ram B6 for pressing the cylinder 2 is controlled so that the pressure applied to the small diameter side and the pressure applied to the large diameter side are the same.

さらに、両側において荷重の均衡を図るために、加圧ラムＣ６に加える圧力Ｌ２と加圧ラムＡ５に加える圧力Ｌ１との差Ｌ３を、加圧ラムＢ７によりシリンダ２に加える。このような加圧方法のもとで、例えばシリンダ２の周囲、すなわち側面に電極を当て、移動式部分焼結等を行う（例えば、特許文献１に示される方法にしたがって）と、細径側から太径側への埋没が抑制され、所望の形状を有する焼結品質が良好な段付き部品を製造することが可能となる。
なお、加圧ラムＣ６については固定の台としてもよい。また、図１においては、片側の加圧ラム数を２本として説明したが、この２本に限定する必要がない。すなわち、必要に応じて加圧ラムの本数を増やしてもよい。 Further, in order to balance the load on both sides, a difference L3 between the pressure L2 applied to the pressure ram C6 and the pressure L1 applied to the pressure ram A5 is applied to the cylinder 2 by the pressure ram B7. Under such a pressurization method, for example, when the electrode is applied to the periphery of the cylinder 2, that is, the side surface, and movable partial sintering or the like is performed (for example, according to the method disclosed in Patent Document 1), the small diameter side Therefore, it is possible to manufacture a stepped part having a desired shape and good sintering quality.
The pressurization ram C6 may be a fixed base. In FIG. 1, the number of pressurization rams on one side is described as two, but it is not necessary to limit to two. That is, you may increase the number of pressurization rams as needed.

図１に示す例において、例えば細径部φ１５ｍｍ、太径部φ２５ｍｍとし、両者に３０ＭＰａ、３５ＭＰａ、４０ＭＰａ、４５ＭＰａ、５０ＭＰａの圧力がかかるような荷重設定を行った場合、その荷重は表１のようにセットできる。
例えば、４５ＭＰａとする場合には、Ｌ１＝８１１ｋｇｆ、Ｌ２＝２２５４ｋｇｆ、Ｌ３＝１４４３ｋｇｆとなる。これらの条件は、数例を示すものであるが、温度や原料粉末の種類により変動することがあるので、実際のテストを通じて、荷重の修正は当然可能である。 In the example shown in FIG. 1, for example, when a small diameter portion φ15 mm and a large diameter portion φ25 mm are set so that pressures of 30 MPa, 35 MPa, 40 MPa, 45 MPa, and 50 MPa are applied to both, the load is as shown in Table 1. Can be set to
For example, in the case of 45 MPa, L1 = 811 kgf, L2 = 2254 kgf, and L3 = 1443 kgf. These conditions are just a few examples, but may vary depending on the temperature and the type of raw material powder, so the load can be corrected through actual tests.

Figure 0004677551
Figure 0004677551

次に、原料粉末の加圧用パンチ及び筒状の空間を形成するシリンダを、加圧用ラムを用いて加圧する場合の例を、図２ａ），ｂ）を用いて説明する。
この例は、図２に示すようにシリンダ２と加圧用ラム５間にスペーサ１０を設け、そのスペーサ１０の厚さを調節することによりパンチＡ３とシリンダ２の加圧のストローク差を制御することができるようにしたものである。固定テーブル９上に、パンチＢ４を配置する。
シリンダ２内には、原料粉末１を充填し、同様にシリンダ２の周囲、すなわち側面に電極を当て、上記と同様に移動式部分焼結等を行う。 Next, an example in which the pressing punch for the raw material powder and the cylinder forming the cylindrical space are pressurized using the pressing ram will be described with reference to FIGS.
In this example, as shown in FIG. 2, a spacer 10 is provided between the cylinder 2 and the pressurization ram 5, and the pressure stroke difference between the punch A3 and the cylinder 2 is controlled by adjusting the thickness of the spacer 10. It is made to be able to. On the fixed table 9, the punch B4 is arranged.
The cylinder 2 is filled with the raw material powder 1, and similarly, an electrode is applied to the periphery of the cylinder 2, that is, the side surface, and movable partial sintering is performed in the same manner as described above.

通電の初期段階では細径側及び太径側ともに収縮するが、加圧ラムＡ５がスペーサ１０に接触した後では、太径側のみが収縮する。したがって、この段階で、太径側の所定長さに亘って緻密化することが可能である。
さらに、図２ｂ）に示すように、電極を細径側へ移動させるとともに、負荷荷重を減じながらスペーサ１０を取り除いて再び通電する。この結果、細径側は太径側に埋没していくことなく、最終的な長さにすることができる。
スペーサ１０の厚さは、非焼結体のサイズ、材料等の焼結条件の変更に応じて任意に変更することができる。このように、スペーサはパンチとシリンダの加圧のストローク差を制御する機能を持つ。 In the initial stage of energization, both the small diameter side and the large diameter side contract, but after the pressure ram A5 contacts the spacer 10, only the large diameter side contracts. Therefore, at this stage, it is possible to densify over a predetermined length on the large diameter side.
Furthermore, as shown in FIG. 2b), the electrode is moved to the small diameter side, and the spacer 10 is removed while reducing the applied load, and the current is supplied again. As a result, the small diameter side can be made the final length without being buried in the large diameter side.
The thickness of the spacer 10 can be arbitrarily changed according to changes in the sintering conditions such as the size and material of the non-sintered body. Thus, the spacer has a function of controlling the stroke difference between the pressurization of the punch and the cylinder.

このように、焼結している部分(通電している部分)の圧力を未焼結の部分の圧力が上回らないよう焼結中に負荷される荷重をうまく制御することによって、段付き部品でも所望の形状に緻密焼結できることを示すものである。
すなわち、太径側焼結と細径側にかかる圧力とを独立して制御し、細径側にかかる圧力を太径側のそれを越えることがないようにすることにより、埋没を抑制することができる。このように、本発明は細径側および太径側ともに同じ圧力に制御することができるため、段付き等の形状を備えた部品への均一な緻密成形が可能となる。 In this way, even with stepped parts, the load applied during sintering is controlled well so that the pressure of the sintered part (the part that is energized) does not exceed the pressure of the unsintered part. It shows that it can be densely sintered into a desired shape.
That is, by controlling the large-diameter side sintering and the pressure on the small-diameter side independently and preventing the pressure on the small-diameter side from exceeding that on the large-diameter side, the burying is suppressed. Can do. As described above, the present invention can control the same pressure on both the small-diameter side and the large-diameter side, so that uniform dense molding to a part having a stepped shape or the like is possible.

図２ａ），ｂ）に示した装置を用いて具体的に焼結した例を示す。固定テーブル９上にパンチＢ４が配置されている。細径側の直径が１５ｍｍ、太径側の直径が２５ｍｍのグラファイト製シリンダ２に、できあがり寸法(緻密化したときの長さ)が細径側および太径側ともに１０ｍｍとなるように、原料粉末１として、それぞれ４．７７ｇ及び１３．２５ｇのアルミニウム粉末を充填した。
また、細径側のシリンダ１上部に、パンチＡ３が貫通する厚さ１２ｍｍ(緻密化したときの長さよりも若干厚め)の穴あきスペーサ１０を挿入した。
そして、充填した原料粉末１をパンチＡ３により、太径側にかかる圧力が４５ＭＰａとなるよう、加圧ラムＡ５を介して２２５０ｋｇｆの荷重で加圧した。
この状態で、太径側に配置した幅１５ｍｍの電極８に通電し、太径側の焼結を実施した。 The example sintered concretely using the apparatus shown to FIG. 2 a), b) is shown. A punch B4 is disposed on the fixed table 9. Raw material powder so that the finished dimension (length when densified) is 10 mm on both the small diameter side and the large diameter side in a graphite cylinder 2 having a diameter on the small diameter side of 15 mm and a diameter on the large diameter side of 25 mm. 1 was filled with 4.77 g and 13.25 g of aluminum powder, respectively.
Further, a perforated spacer 10 having a thickness of 12 mm (slightly thicker than the length when densified) through which the punch A3 penetrates was inserted into the upper portion of the cylinder 1 on the small diameter side.
Then, the filled raw material powder 1 was pressed with a load of 2250 kgf through the pressurizing ram A5 so that the pressure applied to the large diameter side became 45 MPa by the punch A3.
In this state, the electrode 8 having a width of 15 mm arranged on the large diameter side was energized to sinter the large diameter side.

通電の初期段階では、細径側及び太径側ともに収縮するが、加圧ラムＡ５がスペーサ１０に接触した後では、太径側のみが収縮した。その結果、太径側の長さを目的値である１０ｍｍにまで緻密化することができた。
さらに、電極を細径側へ移動し、負荷荷重を９００ｋｇｆ(細径側圧力５０ＭＰａ)に減じながらスペーサ１０を取り除いて再び通電した。その結果、細径側は太径側に埋没していくことなく、最終的にその長さは１０ｍｍとなった。作製されたサンプルの密度を測定したところ、相対密度で９９．６％という値が得られた。 In the initial stage of energization, both the small diameter side and the large diameter side contract, but after the pressurization ram A5 contacts the spacer 10, only the large diameter side contracted. As a result, the length on the large diameter side could be densified to the target value of 10 mm.
Further, the electrode was moved to the small diameter side, the spacer 10 was removed while reducing the load load to 900 kgf (small diameter side pressure: 50 MPa), and the current was supplied again. As a result, the length of the small diameter side was finally 10 mm without being buried in the large diameter side. When the density of the produced sample was measured, a value of 99.6% in relative density was obtained.

比較のために、同様に図３に示す装置を使用し、上記と同様の条件である細径側の直径が１５ｍｍ、太径側の直径が２５ｍｍのグラファイト製シリンダ２に、できあがり寸法(緻密化したときの長さ)が細径側および太径側ともに１０ｍｍとなるように、原料粉末１としてそれぞれ４．７７ｇおよび１３．２５ｇのアルミニウム粉末を充填した例を示す。
この充填した原料粉末１をパンチＡ３により、太径側にかかる圧力が４５Ｐａとなるよう、２２５０ｋｇｆの荷重で加圧した。この状態で、太径側に配置した幅１５ｍｍの電極８に通電し、太径側の焼結を試みた。
しかし、焼結の進行とともに細径側が太径側へ埋没してしまい、所望の形状を得ることができなかった。すなわち、この従来の加圧方法で焼結を行うと、移動式部分焼結を用いても良好な焼結は困難であった。 For comparison, similarly, the apparatus shown in FIG. 3 was used, and the finished dimensions (densification) were performed on a graphite cylinder 2 having a diameter of 15 mm on the small diameter side and a diameter of 25 mm on the large diameter side, which are the same conditions as above. In this example, 4.77 g and 13.25 g of aluminum powder are filled as the raw material powder 1 so that the length of the small diameter side and the large diameter side are 10 mm.
The filled raw material powder 1 was pressed with a load of 2250 kgf by the punch A3 so that the pressure applied to the large diameter side was 45 Pa. In this state, the electrode 8 having a width of 15 mm arranged on the large diameter side was energized to attempt sintering on the large diameter side.
However, as the sintering progressed, the small diameter side was buried in the large diameter side, and a desired shape could not be obtained. That is, when sintering is performed by this conventional pressurizing method, good sintering is difficult even if mobile partial sintering is used.

上記の具体的な本発明の例及び比較の例の結果から明らかなように、焼結している部分(通電している部分)の圧力を未焼結の部分の圧力が上回らないよう焼結中に負荷される荷重をうまく制御することによって、段付き部品でも所望の形状に緻密焼結できることが分かる。
すなわち、太径側焼結中に、加圧ラムＡ５がスペーサ１０に接触した後は、細径側にかかる圧力が太径側のそれを越えることがなくなるため、埋没が抑制される。本発明は、細径側および太径側ともに同じ圧力に制御するため、段付き部材など断面形状が一様ではない部品においても緻密化が十分可能となるものである。 As is clear from the results of the above specific examples of the present invention and comparative examples, sintering is performed so that the pressure of the unsintered portion does not exceed the pressure of the portion that is sintered (the portion that is energized). It can be seen that stepped parts can be densely sintered to a desired shape by well controlling the load applied inside.
That is, after the pressure ram A5 comes into contact with the spacer 10 during the large-diameter side sintering, the pressure applied to the small-diameter side does not exceed that on the large-diameter side, so that burying is suppressed. In the present invention, the same pressure is controlled on both the small diameter side and the large diameter side, so that even a part having a non-uniform cross-sectional shape such as a stepped member can be sufficiently densified.

上記については、断面形状が一様でない、すなわち長手方向に径が変化する焼結体の製造に際して、スペーサを利用した例を用いて説明したが、このようにスペーサを利用しない場合でも、原料粉末の加圧用パンチ及び筒状の空間を形成するシリンダ加圧用のラムに加える荷重を、それぞれ独立に制御することによって、焼結中に形状変化が起こらず、また焼結体の品質が均一であって、さらに焼結性に優れた焼結体を得ることができることが明らかである。
なお、上記に実際の例を示したが、本発明はこれらの例に限定されるものではない。すなわち、本発明の技術思想の範囲で、本実施例以外の態様あるいは変形を全て包含するものである。 The above has been described using an example in which a spacer is used in the production of a sintered body having a non-uniform cross-sectional shape, that is, a diameter changing in the longitudinal direction. By independently controlling the pressure applied to the pressurizing punch and the cylinder pressurizing ram forming the cylindrical space, the shape does not change during sintering and the quality of the sintered body is uniform. Thus, it is apparent that a sintered body having further excellent sinterability can be obtained.
Although actual examples are shown above, the present invention is not limited to these examples. That is, all aspects or modifications other than the embodiment are included within the scope of the technical idea of the present invention.

本発明は、直接通電による加圧焼結法の弱点であった段付き部材など断面形状が一様ではない部品の製造において、優れた効果を発揮する。すなわち、高融点材料や機械加工がきわめて困難な硬い材料でも、段付き等の形状への緻密成形が可能になる。したがって、金属やセラミックス等に対するエネルギーの消費を低減し、作業に要する時間を短縮化する直接通電加圧焼結法に有効であり、形状的な適用範囲を拡大できるので、産業上の効果は非常に大きいものである。   The present invention exhibits an excellent effect in the manufacture of parts having a non-uniform cross-sectional shape, such as a stepped member, which was a weak point of the pressure sintering method by direct energization. That is, even a high melting point material or a hard material that is extremely difficult to machine can be densely formed into a stepped shape. Therefore, it is effective for the direct current pressure sintering method that reduces energy consumption for metals and ceramics and shortens the time required for work. It is a big one.

本発明による、原料粉末両端にかかる圧力をそれぞれ独立に制御しながら、移動式部分焼結等を行うことにより、段付き部品など断面形状が一様でない焼結体を良好に製造する方法に使用する装置の一例を示す概略説明図である。Used in a method for producing a sintered body with a uniform cross-sectional shape such as a stepped part by performing mobile partial sintering while independently controlling the pressure applied to both ends of the raw material powder according to the present invention. It is a schematic explanatory drawing which shows an example of the apparatus to perform. スペーサを使用し、負荷荷重制御による焼結方法を用いた本発明装置の一例を示す概略説明図である。It is a schematic explanatory drawing which shows an example of this invention apparatus using the spacer and using the sintering method by load control. 従来法による段付き部品の製造方法について示した概略説明図である。It is the schematic explanatory drawing shown about the manufacturing method of the stepped component by the conventional method.

符号の説明Explanation of symbols

１：原料粉末
２：シリンダ(焼結用の型)
３：パンチＡ
４：パンチＢ
５：加圧ラムＡ
６：加圧ラムＣ
７：加圧ラムＢ
８：電極
９：固定テーブル
１０：スペーサ（穴あき） 1: Raw powder 2: Cylinder (sintering mold)
3: Punch A
4: Punch B
5: Pressure ram A
6: Pressure ram C
7: Pressure ram B
8: Electrode 9: Fixed table 10: Spacer (perforated)

Claims (2)

筒状の太径部と細径部の空間を有する段付きシリンダ２の型内で、当該型となるシリンダ２の側面に配置した電極８により原料粉末１を直接通電して、長手方向に径が変化する段付き部品を加圧焼結する方法であって、原料粉末１の上下の加圧用パンチ３，４及び筒状の太径部と細径部の空間を形成する段付きシリンダ２を、加圧ラム５を用いて加圧する際に、前記段付きシリンダ２と加圧用ラム５間にスペーサ１０を設け、最初に太径部のみを通電加熱しながら上下のパンチ３，４を加圧することにより太径部と細径部に存在する原料粉末１を収縮させ、次にスペーサ１０を介して段付きシリンダ２の加圧を開始して太径部を収縮させ、次に負荷荷重を減じながらスペーサ１０を取り除き、引き続いて通電加熱部を細径部に移動させて上下の加圧用パンチ３，４を加圧することにより細径部に存在する原料粉末１を収縮させ、加圧ラム５の下面が段付きシリンダ２の上面に到達するまで細径部を収縮させた後、細径部と太径部を同時に加圧して、細径部にかかる圧力を太径部にかかる圧力を超えさせずに焼結することを特徴とする細径部と太径部を有する段付き部品の焼結方法。 In the mold of the stepped cylinder 2 having the space between the cylindrical large diameter part and the small diameter part, the raw material powder 1 is directly energized by the electrode 8 disposed on the side surface of the cylinder 2 to be the mold, and the diameter is increased in the longitudinal direction. Is a method of pressure-sintering a stepped component with a change in the pressure, including a pressurizing punch 3, 4 above and below the raw material powder 1 and a stepped cylinder 2 that forms a space between a cylindrical large diameter portion and a small diameter portion. , when pressurized with a pressure ram 5, a spacer 10 provided between the stepped cylinder 2 and the pressing ram 5, pressurizing the upper and lower punches 3, 4 while only the electrical heating first large-diameter portion Thus, the raw material powder 1 existing in the large diameter portion and the small diameter portion is contracted, and then pressurization of the stepped cylinder 2 is started via the spacer 10 to contract the large diameter portion, and then the load load is reduced. while removing spacer 10, vertically moves the small diameter portion of the electrical heating unit and subsequently After deflating the raw powder 1 present in the small-diameter portion, the lower surface of the pressure ram 5 is deflated the small diameter portion to reach the upper surface of the stepped cylinder 2 by pressurizing the pressurizing punch 3, by applying at the same time pressing the small-diameter portion and the large diameter portion, a stepped having small diameter portion and the large diameter portion, characterized in that the sintered without causing exceed the pressure exerted pressure on the small diameter portion to the large diameter portion Part sintering method. 筒状の太径部と細径部の空間を有する段付きシリンダ２の型内で、当該型となるシリンダ２の側面に配置した電極８により原料粉末１を直接通電して、長手方向に径が変化する段付き部品を加圧焼結する請求項１に記載の焼結方法に用いる装置であって、原料粉末１の上下の加圧用パンチ３，４、筒状の太径部と細径部の空間を形成する段付きシリンダ２、移動できる通電加熱用電極８、取り付け及び取り除きができるスペーサ１０及びこれらのパンチ３，４と前記段付きシリンダ２とを加圧する加圧ラム５を備えていることを特徴とする焼結装置。 In the mold of the stepped cylinder 2 having the space between the cylindrical large diameter part and the small diameter part, the raw material powder 1 is directly energized by the electrode 8 disposed on the side surface of the cylinder 2 to be the mold, and the diameter is increased in the longitudinal direction. The apparatus used in the sintering method according to claim 1, wherein the stepped part having a variable pressure is sintered under pressure, wherein the upper and lower pressing punches 3 and 4 of the raw material powder 1, a cylindrical large diameter portion and a small diameter are used. A stepped cylinder 2 that forms a space of the section, a movable heating electrode 8, a spacer 10 that can be attached and removed, and a pressure ram 5 that pressurizes the punched cylinders 4 , 4 and the stepped cylinder 2. A sintering apparatus characterized by comprising:
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