JPS5982155A - Production of composite casting - Google Patents

Abstract

PURPOSE:To eliminate deviation of particles, gaps among particles, etc. and to produce a casting having uniform and dense composite texture by applying oscillation to a mixture composed of a molten metal and ceramic particles having the specific gravity larger than the specific gravity of said metal in a casting mold. CONSTITUTION:A casting mold is fixed via backing sand 2 in a backing sand case 3 and is installed to an exciter 4, and is also fitted to a tray-shaped receiving base 5 connected to the case 3 by means of rigid stanchions 6 used as oscillation transmission bars. A molten metal M such as ferrous metal and ceramic particles P of carbide or the like having the specific gravity larger than the specific gravity of the metal M and having such a high m.p. that the particles do not melt away in the molten metal are case in a mixed state, the former from a ladle 8 and the latter from a powder charging jig 9, respectively via a casting hopper 7, into the mold 1, in the casting device having the above-mentioned constitution. The metal M is oscillated by the exciter 4 in the stage when the particles P in the mold 1 settle and flocculate on the bottom of the metal M on account of a difference in the specific gravity, whereby the particles are uniformly distributed and the penetration of the molten metal into the clearances among the particles P is accelerated.

Description

【発明の詳細な説明】 本発明は、金属とセラミック粒子とが混在した組織を有
する耐摩耗性等にすぐれた複合鋳物の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a composite casting having a structure in which metal and ceramic particles are mixed and having excellent wear resistance.

金属とセラミック粒子、例えば炭化タングステン（Ｗ２
Ｃ，ＷＣ）などの゛硬質粒子とが混在する複合組織をも
つ材料は、いわば粒子強化型複合材料であって、金属の
みでは得られない特性、例えば高硬度、高耐摩耗性を有
する。本発明者等は、かかる複合材料の鋳造法について
既にいくつかの提案を行った（特願昭５７−１４３１２
０号〜１４．３１２３月等）。Metal and ceramic particles, such as tungsten carbide (W2
A material having a composite structure in which hard particles are mixed, such as C, WC), is a so-called particle-reinforced composite material, and has properties that cannot be obtained with metal alone, such as high hardness and high wear resistance. The present inventors have already made several proposals regarding casting methods for such composite materials (Japanese Patent Application No. 57-14312
0 to 14.312 March, etc.).

それは、鋳型内に金属溶湯と、溶湯上り比重の大きいセ
ラミック粉末とを鋳込み、比重差によってセラミック粒
子を溶湯中に沈降、集積させるものであり、それによっ
て凝集した粒子群と、粒子間隙内に充填された金属とか
らなる緻密、かつ粒子−金属間の結合の強固な複合組織
を有する鋳物を得ることができる。In this method, molten metal and ceramic powder with a high specific gravity are poured into a mold, and the difference in specific gravity causes the ceramic particles to settle and accumulate in the molten metal.This causes the aggregated particles to fill in the spaces between the particles. It is possible to obtain a casting having a dense composite structure consisting of a metal and a solid particle-metal bond.

しかしながら、その製造法においては、金属溶湯等の熱
的条件や粒子の投与位置等の鋳造条件により、時として
鋳物中の粒子の分布の不均一やミクロポロシティなどが
発生する欠点がある。すなわち、 （１）鋳型内に鋳込まれた金属溶湯は、溶湯面か、らの
放熱、鋳型への伝熱、投与された粒子の吸詠等により降
温、粘稠化し易いため、その後の粒子の沈降集積が遅延
し、第３図に示すように粒子（Ｐ）の分布の不均一が生
じる。However, this manufacturing method has the drawback that uneven particle distribution and microporosity in the casting sometimes occur depending on the thermal conditions of the molten metal and casting conditions such as the position of particle injection. In other words, (1) Molten metal poured into a mold tends to cool down and become viscous due to heat dissipation from the molten metal surface, heat transfer to the mold, and absorption of the applied particles. The sedimentation and accumulation of particles (P) is delayed, resulting in non-uniform distribution of particles (P) as shown in FIG.

（１１）溶湯の降温による粘稠化かす＼むと、粒子の凝
集が妨げられるとともに、粒子相互の間隙への溶湯の浸
透が困難となる。すなわち、溶湯の降温とともに粒子表
面に凝固殻が生成し、凝固に伴う収縮が生起するので、
緻密な組織を形成させるには、粒子間を経て溶湯を補給
充填させねばならない。しかるに、粒子表面の凝固殻の
生長によって溶湯補給通路が遮断されてしまうため、第
４図のように、粒子間隙に微小用は巣やミクロポロシテ
ィ（Ｖ）が生じる。(11) When the molten metal becomes viscous as the temperature decreases, it prevents the particles from coagulating and makes it difficult for the molten metal to penetrate into the gaps between the particles. In other words, as the temperature of the molten metal falls, a solidified shell is formed on the particle surface, and shrinkage occurs due to solidification.
In order to form a dense structure, molten metal must be replenished and filled between the particles. However, since the molten metal replenishment path is blocked by the growth of the solidified shell on the surface of the particles, small cavities or microporosity (V) are generated in the gaps between the particles, as shown in FIG.

（ｉｉｌ）投与される粒子は溶湯より比重の大きい重い
粒子であるので、溶湯中を垂直下方向に降下し、横方向
には殆んど移動しない。このため、溶湯面上への分散投
与の際に偏りがあると、その偏りがそのまま複合組織の
層厚の不均一や粒子の粗密のムラとなる。また、粒子の
偏りに伴って、粒子の吸熱による溶湯の降温粘稠化が局
部的に助長されるため、粒子の凝集の不均一化を招来す
る。なお、粒子が溶湯との濡れ性に乏しいものであると
、溶湯面上に投与した際、直ちには溶湯中に取込まれず
、湯面上を浮遊して局部的に偏在する。このことも、複
合組織の層厚や粒子の分布の不均一を生じる原因となる
。(iii) Since the particles to be administered are heavy particles with a higher specific gravity than the molten metal, they fall vertically downward in the molten metal and hardly move laterally. Therefore, if there is any bias when dispersing and dispensing onto the surface of the molten metal, the bias will directly result in non-uniformity in the layer thickness of the composite structure and unevenness in the density of the particles. In addition, as the particles are uneven, the molten metal is locally accelerated to become viscous as the temperature decreases due to heat absorption by the particles, resulting in non-uniform aggregation of the particles. Note that if the particles have poor wettability with the molten metal, when applied onto the molten metal surface, they will not be immediately incorporated into the molten metal, but will float on the molten metal surface and be locally unevenly distributed. This also causes non-uniformity in the layer thickness and particle distribution of the composite structure.

このような粒子の不均一な分布は、複合材料の性能を著
しく損い、またミクロポロシティの存在は材料の致命的
欠陥となる。Such non-uniform distribution of particles significantly impairs the performance of the composite material, and the presence of microporosity is a fatal flaw in the material.

本発明の複合鋳物の製造法は上記問題を解消したもので
あり、その特徴とするところは、鋳型内のセラミック粒
子の沈降凝集過程において、金属溶湯に振動を付与する
ことにより、溶湯中の粒子の偏りを解消するとともに、
粒子間隙への溶湯の浸透を促進するようにしたことにあ
る。これによって、セラミック粒子の不均一分布やミク
ロ的鋳造欠陥が生じるような鋳造条件のもとでも、その
ような不具合を回避し、緻密かつ均一性にすぐれた複合
組織を有する鋳物を得ることを可能にし、た。The method for manufacturing composite castings of the present invention solves the above problems, and is characterized by applying vibration to the molten metal during the sedimentation and agglomeration process of the ceramic particles in the mold. In addition to eliminating the bias of
The reason is that the penetration of the molten metal into the gaps between particles is promoted. As a result, even under casting conditions that cause uneven distribution of ceramic particles or microscopic casting defects, it is possible to avoid such defects and obtain castings with a dense and highly uniform composite structure. I did it.

第１図は本発明の具体例を示す。（１）は鋳型、（４）
は加振装置、（７）゛は鋳込みホッパー、（８）は取鍋
、（９）は粉末流量調節弁（１０）を有するセラミック
粉末投与治具である。FIG. 1 shows a specific example of the invention. (1) is the mold, (4)
(7) is a casting hopper, (8) is a ladle, and (9) is a ceramic powder dosing jig having a powder flow rate control valve (10).

鋳型（１）は例えば精密鋳造用保温モールドであり、バ
ックサンド（２）にてバックサンドケース（３）内に固
定されて加振装置（４）に設置されている。なお、図の
例では、加振装置から鋳型（１）に対する振動の伝達の
効率化のために、鋳型（１）は皿状の受は台（５）に嵌
着され、かつ、該受は台は、振動伝達棒としての剛性支
柱（６）にてケース（３）と連結されている。The mold (1) is, for example, a heat-insulating mold for precision casting, and is fixed in a back sand case (3) with a back sand (2) and installed in a vibrating device (4). In the example shown in the figure, in order to improve the efficiency of transmitting vibrations from the vibration device to the mold (1), the mold (1) has a dish-shaped receiver fitted to the stand (5), and the receiver is The stand is connected to the case (3) by a rigid support (6) serving as a vibration transmission rod.

上記鋳造装置において、金属溶湯（Ｍ）は取鍋（８）か
ら、セラミック粉末（Ｐ）は投与治具（９）からそれぞ
れ供給され、鋳込みホッパー（７）を介して混合状態と
なって鋳型（１）内に鋳込まれる。鋳型（１）内に金属
溶湯との混合物として鋳込まれたセラミック粒子（Ｐ）
は溶湯との比重差により底部へ沈降、凝集する。その沈
降、凝集過程において、加振装置（４）を作動し、鋳型
内の溶湯に振動を付与する。In the above casting apparatus, the molten metal (M) is supplied from the ladle (8), and the ceramic powder (P) is supplied from the dosing jig (9), and they are mixed through the casting hopper (7) and molded into the mold ( 1) to be cast inside. Ceramic particles (P) cast as a mixture with molten metal in the mold (1)
It settles to the bottom and coagulates due to the difference in specific gravity with the molten metal. During the sedimentation and coagulation process, the vibration device (4) is activated to apply vibration to the molten metal in the mold.

、加振された溶湯は、その動きによって粒子（Ｐ）の間
隙への浸透が促進される。また、加振効果は粒子自体に
も加わり、粒子（Ｐ）の動きによって粒子の分布の偏り
が平坦化される。この粒子の移動は、さらに粒子間隙へ
の溶湯の補給、ミクロポロシティと溶湯の置換を促進す
る。また、このような溶湯および粒子の運動に伴う撹拌
効果により、溶湯の局部的な温度差、例えば粒子の吸熱
で生じた粒子近傍の低温粘稠層が拡散均一化される結果
、粒子の均一な凝集、粒子間隙への溶湯の補給、緻密化
が助長される。かくして、粒子の沈降凝集を終えたのち
、溶湯の凝固完了を待って、第２図に示すような粒子分
布の偏りやミクロポロシティのない健全な複合鋳物を得
る。その複合組織において粒子の占める割合（粒子充填
率）は約６０〜７５％（容積％）である。The movement of the vibrated molten metal promotes penetration of the particles (P) into the gaps. Further, the vibration effect is applied to the particles themselves, and the movement of the particles (P) flattens the uneven distribution of the particles. This movement of particles further promotes the replenishment of molten metal into interparticle spaces and the replacement of microporosity with molten metal. In addition, due to the stirring effect accompanying the movement of the molten metal and particles, local temperature differences in the molten metal, such as the low-temperature viscous layer near the particles caused by heat absorption by the particles, are diffused and homogenized, resulting in uniform particle formation. Coagulation, replenishment of molten metal into interparticle gaps, and densification are promoted. In this way, after finishing the sedimentation and coagulation of the particles, and waiting for the completion of solidification of the molten metal, a sound composite casting without uneven particle distribution or microporosity as shown in FIG. 2 is obtained. The proportion of particles in the composite structure (particle filling rate) is about 60 to 75% (volume %).

本発明において、鋳型内の溶湯に対する加振は、鋳造の
開始と同時に、もしくは一定量鋳込まれたのち、あるい
は鋳造終了後に開始され、粒子の沈降、凝集過程に右い
て、適時断続して、または連続的に行なわれる。もつと
も、溶湯の凝固開始具。In the present invention, the vibration of the molten metal in the mold is started at the same time as the start of casting, after a certain amount has been poured, or after the end of casting, and is intermittently applied depending on the sedimentation and agglomeration process of particles. or continuously. Basically, it is a tool to start solidifying molten metal.

・降に加振を継続することは無意味であるばかりが、凝
固相に微細なりランクが発生ずるおそれがあるので、凝
固開始までの間に加振を完了することを要する。・It is not only pointless to continue excitation during precipitation, but it may cause fine ranks to occur in the solidification phase, so it is necessary to complete the excitation before solidification starts.

加振の方法は、前記のように鋳型を振動装置の上に載置
、固定して行うほか、鋳型自体に加振してもよく、ある
いは振動子を鋳型内溶湯に接触させて直接溶湯に振動を
与えるようにしてもよい。Vibration can be carried out by placing and fixing the mold on a vibrating device as described above, or by vibrating the mold itself, or by bringing a vibrator into contact with the molten metal in the mold and directly touching the molten metal. Vibration may also be applied.

振動は、上下動、前後動、または左右動であり、あるい
はこれらが適宜組合せられる。その振動数、振幅、加速
度等の振動条件は、鋳型形状、鋳造量、その他の鋳造条
件により一様ではないが、例えば振動数約８００〜３６
００１１１ｉ振幅は上下動の場合、約０・５〜２πｍの
振動を付与することにより好結果が得られる。The vibration is a vertical movement, a longitudinal movement, a horizontal movement, or a combination of these as appropriate. The vibration conditions such as frequency, amplitude, and acceleration vary depending on the mold shape, casting amount, and other casting conditions, but for example, the vibration frequency is approximately 800 to 36.
00111i In the case of vertical motion, good results can be obtained by applying a vibration of about 0.5 to 2πm.

本発明の鋳造における鋳型の種類および形状は、前記例
示のものに限らず、例えば金型鋳型であってもよく、ま
たその形状も目的とする鋳物の形状に応じたものが適用
される。その鋳造態様は、前記例示のように、金属溶湯
とセラミック粒子とを鋳込みホッパー（７）を′介して
混合状態として鋳込むほか、溶湯と粒子とを各別に鋳型
内に鋳造してもよい。更に、目的とする鋳物が、例えば
中空円筒体である場合には、その鋳型の開口端にそって
鋳込みホッパーや粉末投与治具を複数個配設し、それぞ
れから同時に鋳造を行うようにすることもできる。また
、鋳造過程での溶湯の降温を抑制するために、必要なら
ば、鋳型や投与される粉末を予熱（例えば温度３００°
Ｃ以上）しておくことも有効である。The type and shape of the mold in the casting of the present invention is not limited to the above-mentioned examples, and may be, for example, a metal mold, and the shape can be adapted to the shape of the intended casting. As for the casting mode, the molten metal and the ceramic particles are cast in a mixed state through the casting hopper (7) as described above, or the molten metal and the particles may be cast separately into a mold. Furthermore, if the target casting is a hollow cylindrical body, for example, a plurality of casting hoppers or powder dosing jigs may be arranged along the open end of the mold, and casting may be performed simultaneously from each of them. You can also do it. In addition, in order to suppress the temperature drop of the molten metal during the casting process, if necessary, the mold and the powder to be dispensed may be preheated (for example, to a temperature of 300°C).
It is also effective to do so (C or higher).

本発明に使用される金属溶湯は、目的とする鋳物の用途
、要求回能に応じて選らばれる鉄系または非鉄系の各種
金属もしくは合金である。一方、セラミック粒子は、炭
化物、窒化物、珪化物、はう化物などの粒子が目的に応
じて使用される。もちろん、その粒子は金属溶湯の中で
容易に溶融消失しない高融点を有し、かつ溶湯より大き
い比重を有するものが選らばれる。粒子のサイズは、溶
湯中の沈降促進および得られる鋳物の利質の点から、粒
径５０〜３００μｍのものが好ましい。The molten metal used in the present invention is a variety of ferrous or non-ferrous metals or alloys selected depending on the intended use of the casting and the required performance. On the other hand, as ceramic particles, particles of carbide, nitride, silicide, ferride, etc. are used depending on the purpose. Of course, the particles are selected to have a high melting point so that they do not easily melt and disappear in the molten metal, and have a specific gravity greater than that of the molten metal. The particle size is preferably 50 to 300 μm from the viewpoint of promoting sedimentation in the molten metal and improving the quality of the resulting casting.

また、耐摩耗鋳物を°目的とするときは粒子自体硬度の
高いもの程、有利なことは言うまでもない。Furthermore, when the purpose is to produce wear-resistant castings, it goes without saying that the harder the particles themselves, the more advantageous they are.

例えば、鉄系金属との組合せによる耐摩耗鋳物の鋳造に
は、タングステン炭化物（ＷＣ，、Ｗ２Ｃ）やタングス
テンチタン炭化物などの硬質炭化物粒子が好適である。For example, hard carbide particles such as tungsten carbide (WC, W2C) and tungsten titanium carbide are suitable for casting wear-resistant castings in combination with iron-based metals.

なお、セラミック粉末を鋳型内の溶湯面より散布投与す
る鋳造態様において、溶湯との濡れ性に乏しい粒子を使
用する場合でも、加振効果によって粒子は比較的早く溶
湯内に取込まれるので、場面上での浮遊、移動とそれに
伴う分布の偏りも著しく緩和される。In addition, in the casting mode where ceramic powder is sprayed from the surface of the molten metal in the mold, even if particles with poor wettability with the molten metal are used, the particles are incorporated into the molten metal relatively quickly due to the vibration effect, so it is possible to Floating and moving above the surface and the resulting bias in distribution are also significantly alleviated.

次に本発明の実施例について説明する。Next, examples of the present invention will be described.

実施例　　− 第１図の鋳造装置において、金属溶湯としてニハード鋳
鉄溶１（Ｃ３，２１％、ＳｉＯ，７９％、Ｍｎ０．６８
％、Ｎｉ４．４３％、Ｃｒ１．６０％、Ｍ。Example - In the casting apparatus shown in Fig. 1, nihard cast iron melt 1 (C3, 21%, SiO, 79%, Mn 0.68
%, Ni4.43%, Cr1.60%, M.

０．４１％）４５Ｋｇおよびセラミック粉末として粒径
１５０〜２５０μｍのタングステン炭化物（Ｗ２Ｃ）粉
末１５Ｋｇを鋳造し、振動装置による振動を付与した。0.41%) and 15 kg of tungsten carbide (W2C) powder having a particle size of 150 to 250 μm as ceramic powder were cast and subjected to vibration using a vibration device.

鋳型（１）は精密鋳造用保温モールドであり、その予熱
温度は８５σ°Ｃである。溶湯の鋳造温度は１６５０°
Ｃであり、タングステン炭化物粉末は４００℃に予熱し
て投与した。溶湯に対する加振は、鋳造開始から凝固開
始までの間、連続的に行った。その振動数は１８００［
ｆｆｌ／分、振幅は１　ｍｍである。The mold (1) is a heat-retaining mold for precision casting, and its preheating temperature is 85σ°C. The casting temperature of the molten metal is 1650°
C, and the tungsten carbide powder was preheated to 400°C and administered. The molten metal was continuously vibrated from the start of casting to the start of solidification. Its frequency is 1800 [
ffl/min, amplitude 1 mm.

凝固開始後、加振を停止し、そのまま凝固を完了させた
。得られた中実円柱状鋳物（製品部品のサイズ：直径１
６０＋ｕ＋Ｘ長さ６０ｙｕ＋）の複合組織における粒子
の充填率はその全体にわたって７０〜７５％と極めて均
一であり、かつ粒子間隙のミクロポロシティは全く存在
しない。また、その硬度も、全体にわたりＨＲＡ８２〜
８４と非常に均質である。After the coagulation started, the vibration was stopped and the coagulation was completed. The obtained solid cylindrical casting (product part size: diameter 1
The packing ratio of particles in the composite structure of 60+u+X length 60yu+) is extremely uniform at 70 to 75% over the entire structure, and there is no microporosity between the particles. In addition, its hardness is HRA82~
84, which is very homogeneous.

本発明によれば、投与される粒子の不均一分布やミクロ
的鋳造欠陥の生じるような鋳造条件下でも、粒子の偏り
や粒子間の空隙等を解消し、均一かつ緻密な複合組織を
有する鋳物を得ることができる。得られる鋳物は、特に
耐Ｆ？耗材料として好適であり、その均質性により、す
ぐれた性能と信頼性を保証する。According to the present invention, even under casting conditions that cause uneven distribution of particles and microscopic casting defects, unevenness of particles and voids between particles can be eliminated, and castings with a uniform and dense composite structure can be produced. can be obtained. Is the resulting casting particularly resistant to F? It is suitable as a wear material and its homogeneity ensures excellent performance and reliability.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の鋳造要領の具体例を示す断面説明図、
第２図および第３図は複合組織の模式的説明図、第４図
は第３図のＡ部の拡大図である。 １：鋳型、４：振動装置、７：鋳込みホッパー、Ｍ：金
属、Ｐ：粒子。 代理人　弁理士　宮　崎　新へ部 特開％ｆ５９−８２１５５　（４） ９ 女 Ｔ。 Ｍ ヒ・ ・−６FIG. 1 is a cross-sectional explanatory diagram showing a specific example of the casting procedure of the present invention,
FIGS. 2 and 3 are schematic illustrations of the composite structure, and FIG. 4 is an enlarged view of section A in FIG. 3. 1: Mold, 4: Vibrator, 7: Casting hopper, M: Metal, P: Particle. Agent Patent Attorney Arata Miyazaki Special Publication% f59-82155 (4) 9 Female T. M Hi・・−6

Claims (2)

【特許請求の範囲】[Claims] （１）　　金属溶湯と該溶湯より比重の大きいセラミッ
ク粒子とを各別にもしくは混合状態で鋳型内に鋳込み金
属とセラミック粒子とからなる複合組織を有する鋳物を
製造する方法において、鋳型内の金属溶湯および粒子に
振動を付与することにより、粒子の分布の均一化と、粒
子間隙への溶湯の浸透を促進させることを特徴とする複
合鋳物の製造法。(1) A method for manufacturing a casting having a composite structure consisting of metal and ceramic particles by casting a molten metal and ceramic particles having a specific gravity higher than that of the molten metal into a mold separately or in a mixed state. A method for manufacturing composite castings, characterized by applying vibration to the particles to make the distribution of the particles uniform and to promote the penetration of molten metal into the gaps between the particles. （２）金属が鉄系金属であり、セラミック粒子が炭化物
系セラミック粒子であることを特徴とする上記第（１）
項に記載の複合鋳物の製造法。(2) Item (1) above, wherein the metal is an iron-based metal and the ceramic particles are carbide-based ceramic particles.
The manufacturing method for composite castings described in Section.