JP4271421B2 - Die casting prototype manufacturing method and die casting product prototype manufacturing method - Google Patents

Description

【００６７】
砂型表面の拡大写真から三河珪砂７号の砂型１では、粒径が大きく、砂と砂との間に大きな隙間が見られた。また、三河珪砂８号の砂型２では、砂型１よりも粒径が小さいため隙間は減少しているが、まだ砂と砂との間に隙間が見られた。これに対して、粒子径の細かいジルコンフラワをブレンドして混練して造形され砂型３では、隙間がジルコンフラワによって埋められ、鋳型表面は詰まりが良好であった。
【００６８】
つぎに、これらの砂型１〜３を用いて実際に鋳造して得られた鋳造品の表面粗さを測定した。実験は、各砂型１〜３をそのまま用いたり（塗型なし）、塗型剤を刷毛塗り又はスプレー塗りにより塗布して各実験を行った。なお、塗型剤を刷毛塗りした場合には、塗型剤を塗布乾燥した後に柔らかい布で表面をなぞることにより刷毛痕によりできる大きな凹凸を消した。
【００６９】
結果を図５に示した。図５より明らかなとおり、塗型剤を塗布することにより表面粗さは向上し、さらに塗型剤の塗布方法として刷毛塗りが優れていた。また、砂型の種類に関しては、砂型３＞砂型２＞砂型１の順で表面の平滑性が向上していた。
【００７０】
つぎに、ジルコンフラワの最適配合割合を確認するために三河珪砂８号にジルコンフラワの配合割合を種々変化させて砂型を製作し、同様にして鋳肌の表面粗さを測定し、結果を図６に示した。
【００７１】
この図６において、塗型剤ありは、塗型剤を厚さ２０μｍ〜１００μｍの範囲内となるように塗布している。この結果、鋳物砂として珪砂にジルコンフラワのような微粒子状の鋳物砂を配合することにより、鋳肌が改善されることが確認された。また、塗型剤の塗布により何れの場合も鋳肌が改善されていた。
【００７２】
なお、三河珪砂８号に配合されるジルコンフラワの量が６０質量％を超えて多く混合した砂型を製作したが、この表面は砂型３に比較して粗くなってしまった。この原因としては、用いた混練機の混練が十分にできなかったためと考えられるが、いずれにしても、過度に細かい砂だけでは十分に平滑な表面を生産効率よく作製することが困難であると思われた。
【００７３】
以上の結果から、鋳肌が平滑であることが必要なダイカスト法の試作品が要求される場合には、ジルコンフラワなどの微粉末を適宜の割合で混合して造形された砂型を用いることがよく、その砂型に塗型剤を塗布すると更に鋳肌が向上されることが確認された。
【００７４】
また、この場合、１００メッシュ乃至２００メッシュ（７号又は８号砂）、好ましくは１５０メッシュ乃至２００メッシュ（８号砂）の範囲内及び３００メッシュ以下（微粉末）にそれぞれ粒度分布の極大値を有し、３５０メッシュ以下の微粒子（微粉末）の占める割合が全鋳物砂の１０質量％以上６０質量％以下、特に好ましくは２０質量％以上５０質量％以下の範囲内で含有されている鋳物砂より造形された砂型を用いることにより、低圧鋳造法でも改善された鋳肌を備えた試作品を製造することができることが確認された。また、この場合の微粒子の配合割合に最適値があることが確認された。
［実施例２］
この実施例２は、本発明で用いる砂型低圧鋳造品が実体強度試験を伴うダイカスト製品の試作品としても有効に利用できることを確認するための実施例である。いずれの実施例でも砂型のキャビティとしてテストピース用のものを採用した以外は上述した図１に示される製造装置と実質的に同一の装置を用いて以下の実験を行った。
【００７５】
ダイカスト試作品としては、実体強度試験を行うことが多い。それ故、ダイカスト試作品としては実機による量産されるダイカスト製品と同程度の実体強度を備えていることが要求される。そこで、板厚２，４，６ｍｍのテストピースを上述した製造装置と実質的に同一の装置を用いて以下の実験を行った。
【００７６】
本実施例におけるダイカスト製品の試作品としての目標値は、引張強さ：２００ＭＰａ以上、０．２％耐力：１２０ＭＰａ以上、伸び：１０％以上であるので、試作品を製作する材料には流動性がよく、熱処理により特性値の向上が可能なＡＣ４ＣＨ合金を用いた。
【００７７】
実施例１に従う低圧鋳造品と実質的に同一の装置により鋳造品（Ｆ）を作製したところ、何れの厚みのテストピースも目標値を満足することはなかった。
【００７８】
そこで、溶体化処理５４０°Ｃ×６時間（水焼き入れ）、時効１５０°Ｃ×２時間の条件で熱処理を行ったところ厚みが４ｍｍ以下のテストピースでは熱処理により目標値を達成することが確認された。
【００７９】
以上の結果をまとめて図７に示した。ここで、この熱処理していないテストピースは符号Ｆで示し、溶体化処理のみのテストピースを符号Ｔ４で示し、溶体化処理と時効処理を行ったテストピースを符号Ｔ６で示した。
【００８０】
肉厚が６ｍｍの場合には溶体化処理時間が長いと伸びが目標値を下回ったが、溶体化処理時間を４時間に設定すれば目標値をクリアすることができる。これにより、熱処理条件を変更させることにより目標値を達成することができると考えられる。
【００８１】
以上の結果より、砂型低圧鋳造法において、得られた鋳造品を熱処理することにより、実体強度試験が必要なダイカスト製品が目標の場合にも、実体強度試験に耐える試作品を作製することができることが理解される。
［実施例３］
この実施例３は、本発明で用いる砂型低圧鋳造品が形状がダイカスト製品と略同一のものが得られることを実証するためのものである。この点、本発明においては、薄物大型鋳造品を得るための試作品の製造を目的としているので、本発明に従う試作品の製造方法において同一形状のものが得られるか否かを定量的に理解するには、簡易には流動長を把握することである。
【００８２】
そこで、この実施例では、図８に示すように、肉厚が１．５ｍｍ、２ｍｍ、４ｍｍ及び６ｍｍからなる流動性試験用木型から造形した砂型を用いて流動長を測定する実験を行った。本発明に従う砂型低圧鋳造法が優れていることを実証するために対照例として砂型重力鋳造法でも実験を行った。
【００８３】
結果をまとめて図９に示した。この図９において、ＡＤＰ法と略されている結果は、図１に示される製造装置と実質的に同一の装置を用いて行った結果であり、砂型低圧鋳造法は図１に示される製造装置において、チャンバー２９内に燃焼防止ガス又は酸化防止ガスを供給せずに大気雰囲気で行った実施例である。
【００８４】
砂型低圧鋳造法では酸化膜防止の有無にかかわらず何れの場合にも、肉厚が１．５ｍｍでは流動長が略２５０ｍｍ、肉厚が２ｍｍでは流動長が４００ｍｍ以上と砂型重力鋳造法に対比して略２倍の長さの流動長が得れた。
【００８５】
これにより、砂型低圧鋳造法に従えば、砂型重力鋳造法に比較して長い流動長を確保することが可能であり、これにより、砂型低圧鋳造法に従えば、砂型重力鋳造法に対比してダイカスト製品と略同一形状の試作品を製造しやすいことが確認された。
【００８６】
また、砂型低圧鋳造法に従えば、厚み（ｔ）が４ｍｍ以下であり、一辺の長さが少なくとも２００ｍｍ以上であり、かつ、長さ（ｌ）／厚み（ｔ）が５０以上で定義されるような薄物大型鋳造品の試作品がキャビティへ通じるインゲート（セキ、湯口）の数を複数個（多数）配置すれば、実体強度を備えた鋳造品が得られることが確認された。
【００８７】
また、また、以上により得られた鋳造品は、電磁シールド性にも優れたアルミニウム合金又はマグネシウム合金より形成されているので、電化製品や自動車部品などの試作品としての普及が期待される。
【００８８】
【発明の効果】
以上説明してきたように、本発明によれば、薄物大型鋳造品をダイカスト法にて大量生産するためにダイカスト製品の設計図から量産金型を製作するに当たって、砂型低圧鋳造法により量産時と同一材料を用いて製品を鋳造試作し、該鋳造試作により得られた試作品の実製品としての評価結果を基にして量産金型を製作すれば、廉価でかつリスクを伴わずにダイカスト法により薄物大型鋳造品の量産金型を製作できる、という実用上有益な効果を発揮し得る。
【図面の簡単な説明】
【図１】本発明の実施の形態の側方断面図である。
【図２】図１の作動図である。
【図３】図１によって得られる製品を示す図である。
【図４】図１によって得られる製品を示す他の図である。
【図５】実施例により得られる試作品の表面粗さを測定した結果を示す図である。
【図６】実施例により得られる試作品の表面粗さを測定した結果を示す図である。
【図７】実施例により得られる試作品の引張強さを測定した結果を示す図である。
【図８】実施例に用いられた流動長試験用木型を説明する平面図である。
【図９】流動長試験結果を示す図である。
【符号の説明】
２ 軽金属溶湯
３ ルツボ
１１ 砂型
１６ キャビティ
１７ 湯口
２１ ストーク
２５ 薄物大型鋳造品
２８ 酸化防止ガスまたは燃焼防止用ガス
２９ チャンバー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a die casting prototype manufacturing method and a die casting product prototype manufacturing method.
[0002]
[Prior art]
In recent years, it has become necessary to increase the recycling rate of various parts such as automobiles as well as electric products such as televisions. Here, various plastic products are used as these materials, but these plastic products have a problem that it is difficult to completely recycle by repeatedly using the same material for the same product.
[0003]
On the other hand, light metal materials such as aluminum alloys and magnesium alloys can be die-cast using a mass production mold. According to die casting using such light metal materials, the same material can be applied several times to the same part. But it has the feature of being reusable. Therefore, some plastic products are being converted into easily recyclable aluminum and magnesium alloys.
[0004]
Under such circumstances, die casting using an aluminum alloy or a magnesium alloy is becoming widespread, and for example, it is used for casting parts that require strength and toughness such as knuckle housings, arms, and differential cases for automobiles. .
[0005]
In such a die cast product, a mold made of a metal material that can withstand high pressure and does not react with the injected light metal is used. However, since such a mold is expensive, before entering mass production (mass production). A sand mold that can be made inexpensive is used as a prototype (see, for example, Patent Document 1). In this trial production stage, several trial productions are carried out. In each stage, several to several tens of trial products are cast, various tests necessary for actual products are conducted, and a design drawing of the die cast product is prepared. Corrections are made.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-57965 (see paragraph numbers 0001 and 0004)
[0007]
[Problems to be solved by the invention]
However, examples of mass production of thin large castings by the die casting method (die casting method) have not been reported or are not widely used. This is due to the fact that a good technique for producing a thin large casting using a sand mold has not been developed.
[0008]
That is, if a die casting method using a die is used even in a thin large casting, a good casting can be obtained relatively easily by pouring molten metal into the die at a high pressure of 40 to 80 MPa. It is considered possible. However, a die casting die that can withstand such a high pressure for producing a thin large casting is very expensive. Therefore, according to the die casting method, the prototype mold becomes expensive, and mass production is accompanied by a large cost risk. This is the biggest problem, and mass production of thin large castings by the die casting method is not widespread. In a thin large casting, an inexpensive mold manufacturing method capable of providing a prototype having substantially the same performance as that actually sold is desired.
[0009]
Conventionally, various casting methods using sand molds have been proposed. In particular, the sand mold low pressure casting method (low pressure casting method using sand molds) is one good that can obtain relatively good castings from light metal materials such as aluminum and magnesium alloys. Is the method. Such a sand-type low pressure casting method is 0.049 MPa (0.5 kg / cm) with respect to the molten metal surface of the light metal stored in the crucible (melting furnace).²) This is a method of pushing up molten metal by applying a low pressure and injecting it into a sand mold cavity through a stalk (pipe). Compared to the gravity casting method using a sand mold, a cast product with few internal defects can be obtained even if a thin object is cast.
[0010]
However, even with the conventionally proposed sand-type low pressure casting method, for example, when a thin cast product becomes large, a good cast product cannot be obtained. The reason for this is thought to be largely due to the fact that the injected metal melt is slowly injected at a low pressure, so that the light metal melt is cooled by the sand mold, and it is difficult for the melt to reach every corner in the cavity. In addition, when an aluminum alloy or a magnesium alloy is used as a metal material, the surface of the metal material is likely to be oxidized.
[0011]
Therefore, it is difficult to produce thin large castings with sand molds, so several trial stages are required, and from several to tens of trials in each stage, actual products For large thin castings that do not reduce the risk of mass production as actual products unless the various tests required are performed, it is considered that practically effective prototypes cannot be obtained at low prices, and thin large castings It seems that product research has not progressed for a long time.
[0012]
In recent years, for example, large-sized televisions are rapidly developing as one of household appliances requiring recycling. In addition, the demand for recycling of automobile parts is increasing rapidly.
[0013]
Therefore, an object of the present invention is to provide a die casting prototype manufacturing method and a die casting product trial manufacturing method that can spread the mass production of thin large cast products.
[0014]
[Means for Solving the Problems]
  Under such circumstances, the present inventors have disclosed Japanese Patent Application No. 2002-182746 filed on June 24, 2002 (JP 2004-82211 A)Has already proposed an invention relating to a “manufacturing apparatus for a thin large casting” (hereinafter referred to as a prior invention). According to the invention of the prior application, a manufacturing apparatus for a thin, large-sized cast product that applies pressure to the molten metal surface of the molten metal stored in the crucible and pushes the molten molten metal into the sand mold cavity via the stalk. A thin large casting having a cavity for casting a thin large casting, a plurality of gates provided in the cavity, and a chamber capable of supplying an antioxidant gas or a combustion preventing gas in the middle of the stalk. A manufacturing apparatus is provided. And if such a manufacturing apparatus is used, even if it is a sand type | mold low pressure casting method, a thin large sized casting can be obtained now.
[0015]
In addition, the inventors have obtained a casting apparatus obtained by improving the manufacturing apparatus disclosed in the prior invention or by improving the apparatus, and by researching a manufacturing method of a prototype using the manufacturing apparatus. It was confirmed that the prototype can obtain a prototype that is very close to the die-cast product by mass production in various characteristics and quality. As a result, the casting obtained by this manufacturing apparatus can be sufficiently used for a prototype test. Therefore, it has been recognized that a prototype of a thin large casting can be manufactured at a relatively low cost, and the present invention has been achieved.
[0016]
  That is, the present invention is a die casting prototype characterized by casting a prototype using the same or different material as in mass production by a sand mold low pressure casting method in order to mass-produce thin large castings by the die casting method. It is a manufacturing method.
Here, in the sand mold low pressure casting method, a pressure is applied to the molten metal surface of the light metal melt stored in the crucible, and the apparatus for producing a thin large casting that pushes the light metal melt into the sand mold cavity via stalk, The cavity has a narrow and long cavity for casting the thin large casting, and a plurality of gates are provided in the cavity, and the stalk has a chamber capable of supplying an antioxidant gas or a combustion preventing gas in the middle. The sand mold includes at least a lower mold and an upper mold that form a cavity, and a sand mold (pouring mold) in which a gate or a runner that guides the molten metal to the cavity is formed between the lower mold and the stalk. ) And the sand mold is a manufacturing apparatus for a thin large cast product in which a coating agent is applied.
[0017]
In order to mass-produce thin large castings by die casting method, when producing mass production mold from the design drawing of die casting product, the product is cast by trial using the same material or different material from mass production by sand mold low pressure casting method, Based on the evaluation results as the actual product of the prototype obtained by the casting prototype, for example, by selecting a prototype that conforms to the standard or obtained the best test result, If a mass production mold is manufactured by modifying the design drawing as necessary, it is possible to manufacture a mass production mold for a thin large casting by a die casting method at low cost and without risk.
[0018]
Here, the die casting method is a casting method using a mold, and a so-called pressure casting method is a typical example, but any casting method using a mold is included in the present invention.
[0019]
In the present invention, the thin large cast product means, for example, a product having a thickness t of 4 mm or less and a sufficiently large dimension in the plane direction as a molded product.
[0020]
This thickness t is generally in the range of 1 mm to 3 mm, and typically in the range of 1.5 mm to 2.5 mm. Here, the term “thickness” refers to a flat general portion other than a particularly thick portion such as a mounting seat.
[0021]
The dimension in the planar direction is, for example, that the length of one side is at least 200 mm or more, and generally 500 mm or more. If expressed as the sum of the lengths of the two sides of length and width, for example, the sum is 300 mm or more, and generally the sum is 1000 mm or more. Here, although there is no upper limit of the length, since it is a mold, an extremely large object is substantially difficult to manufacture, and is usually 2000 mm or less.
[0022]
Expressing a preferred thin large casting by the ratio of wall thickness t to length l, the ratio of length (l) / wall thickness (t) is 50 or more, usually 100 or more, typically 200 Even such flat materials can be effectively produced in the present invention.
[0023]
2. The die casting according to claim 1, wherein the sand mold is obtained by further applying a coating agent to a sand mold formed by mixing fine powders having a small particle diameter at an appropriate ratio. This is a manufacturing method for a prototype.
[0024]
If comprised in this way, if it chooses for the smoothness of a casting surface, a prototype can be obtained. Examples of the sand species to be formed include fine powders of fine refractories such as silica and zircon flowers (fine casting sand), and fine powders of fine refractory (fine particles) in addition to coarse casting sand such as silica sand. The casting surface is improved by blending an appropriate amount of casting sand).
[0025]
Such mixed sand has a maximum value of particle size distribution within the range of 100 mesh to 200 mesh and 300 mesh or less when sieved, and the proportion of fine particles of 350 mesh or less is 10% by mass of the total foundry sand. What is contained in the range of 60 mass% or less can be illustrated as a preferable thing. By containing fine particles of foundry sand in an appropriate range, the casting surface is improved with air permeability.
[0026]
In the sand mold formed from such mixed sand, the casting surface is further improved by applying a coating agent.
[0027]
Further, the present invention is characterized in that the cast product obtained by the low pressure casting method is further subjected to heat treatment.
[0028]
If comprised in this way, the prototype provided with the mechanical strength according to a customer's request | requirement can be obtained by heat-processing the casting obtained by the low pressure casting method on appropriate conditions. In the present invention, the mechanical strength of a prototype can be met by selecting an appropriate material or changing the material composition at the prototype stage in order to answer the standard according to the customer's request. However, as in the present invention, it can also be dealt with by subjecting the prototype to further heat treatment. If the customer's request can be met at the prototype stage, a die-casting die as a mass-produced product can be produced, and an optimal material can be selected to meet the customer's request in the mass-produced product. In this case, the material of the final product, the prototype, and the material are often the same or the same system, but may not necessarily be the same and may be different materials. Here, the same system is the same from the viewpoint of an aluminum alloy, but only the detailed composition ratio is different.
[0029]
In the above low pressure casting method, pressure is applied to the molten metal surface of the light metal stored in the melting furnace, pressure is applied to the surface of the molten metal via stalk, the pipe is raised, and the sand mold located at the upper part is placed. A method of casting by pushing up is preferable.
[0030]
Also, a good prototype can be obtained when the sand mold has a narrow and long cavity for casting a thin large casting.
[0031]
In addition, by providing a plurality of gates communicating with the cavity, for example, even when a narrow and long cavity is provided, it is possible to spread the light metal melt to every corner in the cavity.
[0032]
Further, the present invention is characterized in that the stalk has a chamber capable of supplying an antioxidant gas or a combustion preventing gas in the middle.
[0033]
If comprised in this way, an oxide film can be formed on the surface of the melt of light metal injected into the cavity by supplying the antioxidant gas or the combustion preventing gas to the chamber provided in the middle of the stalk (pipe). In other words, an oxide film is unlikely to be generated at the front end of the molten metal flow, and even when pouring from a plurality of gates, it is possible to expect reduction effects such as hot water and hot water boundaries. Thereby, a good cast product with few internal defects can be obtained.
[0034]
According to the present invention, the sand mold includes at least a lower mold and an upper mold that form a cavity, and a gate or a runner that guides the molten metal to the cavity is formed between the lower mold and the stalk. It is characterized by having a sand mold (pouring gate type).
[0035]
If comprised in this way, it will become easy to isolate | separate a sand mold from stalk. In particular, when a large number of castings are repeatedly produced in succession, the production cycle can be shortened while keeping the quality of the prototype constant.
[0036]
In the invention, it is preferable that the molten metal is aluminum or an aluminum alloy, and the antioxidant gas or the combustion preventing gas is an inert gas.
[0037]
According to the present invention, the molten metal is magnesium or a magnesium alloy, and the combustion preventing gas or the combustion preventing gas is a mixed gas of sulfur hexafluoride and carbon dioxide or a gas equivalent thereto. It is characterized by that.
[0038]
  In addition, the present invention is to manufacture a mass production mold from a design drawing of a die cast product.According to the apparatus for manufacturing a thin large casting according to claim 1.Make at least one sand mold and use the sand moldAccording to the method for manufacturing a prototype for die casting according to claim 1The same or different material used for mass production by low pressure castingPrototypeCasting thePrototypeIs a prototype of a die-cast product, characterized in that it determines whether or not the product falls within the standard and manufactures the mass production mold.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described together with illustrated examples.
[0040]
1 to 4 show a manufacturing apparatus for making a prototype of a thin large casting used in the embodiment of the present invention.
[0041]
First, the structure will be described. In this manufacturing apparatus, a crucible 3 for storing the light metal melt 2 is provided inside the furnace body 1. The crucible 3 is hermetically sealed by a lid member 4, and the lid member 4 has a pressurized gas supply port 6 for supplying pressurized gas 5 into the crucible 3 at a low pressure. A pressurized gas supply means 7 is connected to the pressurized gas supply port 6. The furnace body 1 is provided with a heating device 8 such as a gas burner for heating the crucible 3.
[0042]
A mold placing table 12 on which the sand mold 11 is placed is disposed above the furnace body 1. The sand mold 11 is, for example, a three-stage mold having an upper mold 13, a lower mold 14, and a gate mold 15. A cavity 16 is formed between the upper mold 13 and the lower mold 14, a pouring gate 17 connected to the seal leading to the cavity 16 is formed in the lower mold 14, and a light metal melt 2 is connected to the pouring gate 17 in the pouring mold 15. A runner 18 for distributing the water is formed. The runner 18 is opened at a position of an opening 19 formed in the mold table 12.
[0043]
The cavity 16 has a thickness of a cast product of 4 mm or less, and has at least a narrow and long shape with a length of one side of 200 mm or more in a planar dimension as a molded product.
[0044]
A stalk (tube) 21 is disposed between the crucible 3 and the sand mold 11. The stalk 21 is inserted into the light metal melt 2 stored in the crucible 3 at the lower end, and communicated with the lower opening 22 of the runner 18 with the upper end inserted through the opening 19 of the mold table 12.
[0045]
In this embodiment, the sand mold 11 is, for example, an outer frame 23 for a large wall-mounted TV as shown in FIG. 3, a door frame 24 for a car as shown in FIG. 4, or a car seat (not shown). It has a cavity 16 for casting a thin large casting 25 such as a frame.
[0046]
The cavity 16 is provided with a plurality of gates 17 (or weirs). The number of gates 17 is determined by the shape, size, thickness, etc. of the cast product and the width of the gate 17 used, and is, for example, about 10 to 30 pieces.
[0047]
Furthermore, a chamber 29 capable of supplying an antioxidant gas or a combustion preventing gas 28 is provided in the middle of the stalk 21. The chamber 29 has a pot shape having a required volume, and the stalk 21 is separated into an upper stalk 30 and a lower stalk 31 above and below the chamber 29. A cylindrical wall 33 having a length that reaches the substantially central portion of the chamber 29 extends downward from the upper opening 32 of the chamber 29 connected to the upper stalk 30. A hot water level sensor 34 and an antioxidant gas supply port 35 are provided at a position on the outer peripheral side of the cylindrical wall 33 in the upper part of the chamber 29. An antioxidant gas supply means 36 is connected to the antioxidant gas supply port 35. A heat insulating material 37 is attached to the stalk 21.
[0048]
When the light metal melt 2 is aluminum or an aluminum alloy, an inert gas such as nitrogen or argon gas is used as the antioxidant gas 28. In this case, air or the above inert gas is used as the pressurized gas 5.
[0049]
When the light metal melt 2 is magnesium or a magnesium alloy, a combustion preventing gas 28 is used instead of the antioxidant gas. As the combustion preventing gas 28, for example, a mixed gas of sulfur hexafluoride and carbon dioxide or a gas equivalent thereto is used. In this case, the same mixed gas as the combustion preventing gas 28 is used as the pressurized gas 5.
[0050]
Next, the operation of this manufacturing apparatus will be described.
[0051]
First, as shown in FIG. 2A, an antioxidant gas or a combustion preventing gas 28 is supplied to the stalk 21 through the chamber 29 to prevent oxidation of the molten metal surface of the light metal 2 in the stalk 21 or the light metal melt 2. To prevent burning. In this state, a mold apparatus such as a sand mold 11 is set on the mold table 12, and the antioxidant gas or the combustion preventing gas 28 in the stalk 21 is changed depending on the volume of the cavity 16. In this case, the air is sent into the cavity 16 of the sand mold 11 for about 30 seconds, and the air in the cavity 16 is replaced with the antioxidant gas or the combustion preventing gas 28.
[0052]
Next, as shown in FIG. 2B, the supply of the antioxidant gas or the combustion preventing gas 28 to the chamber 29 is stopped, and the molten metal of the light metal 2 stored in the crucible 3 is applied to the molten metal surface by the pressurized gas 5. Pressure is applied at a low pressure, and the molten metal 2 is pushed up into the cavity 16 of the sand mold 11 through the stalk 21. At this time, if the molten metal 2 contacts the antioxidant gas supply port 35 of the chamber 29, the antioxidant gas supply port 35 may be blocked. 2 is detected by a hot water level sensor 34, and when the hot water level reaches a predetermined value, an antioxidant gas or a combustion preventing gas 28 is intermittently injected into the chamber 29, and the hot water level is detected. The surface level should not exceed the predetermined value.
[0053]
After about 40 seconds, when the light metal melt 2 is filled in the cavity 16, the light metal melt 2 in the cavity 16 is solidified by leaving it for about 100 seconds, and then, as shown in FIG. 2 (c). Then, an antioxidant gas or a combustion preventing gas 28 is supplied into the chamber 29 to push down the level of the molten metal to the lower end of the cylindrical wall 33, and further an antioxidant gas or a combustion preventing gas from the lower end of the cylindrical wall 33 into the upper stalk 30. 28 is continuously supplied while bubbling. As a result, the antioxidant gas or the combustion preventing gas 28 is accumulated at the boundary portion between the solidified portion and the unsolidified portion of the light metal melt 2 and separated from each other.
[0054]
After that, as shown in FIG. 2 (d), the pressure by the pressurized gas 5 on the molten metal surface of the light metal melt 2 stored in the crucible 3 is released, and the antioxidant gas or the combustion preventing gas 28 enters the chamber 29. Is supplied to lower the molten metal surface of the light metal 2 in the stalk 21 and prevent the molten metal from oxidizing or burning the light metal molten metal 2. Next, after removing the sand mold 11 from the mold table 12, the sand mold 11 is collapsed to take out the thin large casting 25.
[0055]
Thereafter, the thin large casting 25 can be continuously produced by repeating the above. When removing the sand mold 11 from the mounting table 12, the combustion preventing gas 28 is continuously or intermittently provided so that air does not diffuse into the chamber 29 from the opening of the stalk 11 generated when the sand mold 11 is removed. The supply continues into the chamber 29.
[0056]
As described above, by providing a plurality of gates 17, it is possible to spread the light metal melt 2 to every corner in the narrow and long cavity 16 for casting the thin large casting 25. Further, by supplying the antioxidant gas or the combustion preventing gas 28 to the chamber 29 provided in the middle of the stalk 21, the air in the cavity 16 is replaced with the antioxidant gas or the combustion preventing gas 28, and the inside of the chamber 29 and The cavity is continuously filled with an antioxidant gas or a combustion preventing gas 28. Thereby, it is possible to prevent an oxide film from being formed on the surface of the light metal melt 2 and burning of the light metal melt 2. In addition, an oxide film is unlikely to be generated at the front end of the molten metal flow, and a reduction effect of hot water, hot water boundary, etc. can be expected even when pouring from a plurality of gates (or cisterns). Thereby, a good cast product with few internal defects can be obtained. Further, the strength of the cast product thus obtained has substantial strength as a substitute for the die-cast product.
[0057]
Moreover, a casting surface is improved by blending a zircon flower as a sand seed forming this sand mold.
[0058]
Thereby, even if it is the low pressure casting method using the sand mold | type 11, the thin large sized casting 25 can be obtained now, and the prototype of the thin large sized casting 25 can be manufactured cheaply.
[0059]
Further, by using an inert gas as the antioxidant gas 28, a thin large casting 25 made of aluminum or aluminum alloy can be produced by a low pressure casting method using the sand mold 11.
[0060]
Further, by using a mixed gas of sulfur hexafluoride and carbon dioxide or a gas equivalent thereto as the combustion preventing gas 28, a low-pressure casting method using a sand mold 11 for a thin large casting 25 made of magnesium or a magnesium alloy. Can be produced.
[0061]
If this manufacturing apparatus is used, for example, a thickness of 1.5 to 2.5 mm is about 400 × 600 × 50 (mm) or more, and a thickness of 2.2 to 4.0 mm is about 700 × 1000 × 300 (mm) or more. The thin large casting 25 can be cast. In addition, a large thin product having a size of 1200 × 1000 mm and a thickness of 1.5 mm could be manufactured.
[0062]
In addition, for example, an outer frame 23 for a 42-inch large wall-mounted television having 700 × 1050 × 65 mm and a wall thickness of 2.5 mm can be obtained. In addition, an automobile door inner panel having a thickness of 610 × 1100 and a thickness of 2.0 mm can be manufactured.
[0063]
【Example】
Next, the effect of this invention is demonstrated in detail based on the Example which produced the casting product using the above-mentioned manufacturing apparatus.
[Example 1]
Example 1 is an example for demonstrating that the cast product obtained by the sand-type low pressure casting method used in the present invention can be effectively used as a prototype requiring smoothness of the casting surface. In any of the examples, the following experiment was performed using substantially the same apparatus as the manufacturing apparatus shown in FIG. 1 described above except that a sand mold cavity was used for the test piece.
[0064]
The die casting prototype may require a casting surface close to the casting surface of the die casting product, including the case where a coating is applied to the surface of the prototype. In general, when using a sand mold and pouring under pressure, the casting surface becomes rough and improvement of the casting surface is required. Therefore, the following sand mold molding was a resin self-hardening mold. According to the research of the casting surface by the present inventors, the Rz (surface roughness) of the casting surface is 69 μm in a general gravity casting product (casting product by sand type gravity casting method), and the low pressure casting according to the manufacturing apparatus of the present invention. In the product, since the molten metal enters the gap between the sand grains, Rz is 212 μm, and it has been confirmed that the surface roughness is larger than that of the die-cast product.
[0065]
In this experiment, three kinds of sand, Mikawa silica sand No. 7, Mikawa silica sand No. 8, and zirconia flower, having different particle diameters were prepared as the sand species, and the surface roughness was improved. Here, the particle sizes are Mikawa Silica No. 7> Mikawa Silica Sand No. 8> Zirconia Flower, and the sand molds are Mikawa Silica Sand No. 7 (sand mold 1), Mikawa Silica Sand No. 8 (sand mold 2), Mikawa Silica Sand No. 8 + Three types of zircon flower 1: 1 (sand mold 3) were prepared. Table 1 shows the particle size distribution of each sand. Here, a standard sieve made by Tyler was used as the sieve.
[0066]
[Table 1]

[0067]
From the enlarged photograph of the sand mold surface, the sand mold 1 of Mikawa Silica No. 7 had a large particle size and a large gap was observed between the sand and sand. Further, in the sand mold 2 of the Mikawa Silica Sand No. 8, the particle size was smaller than that of the sand mold 1, so the gap was reduced, but there was still a gap between the sand and the sand. In contrast, the sand mold 3 was formed by blending and kneading zircon flowers with fine particle diameters, and the gaps were filled with the zircon flowers, and the mold surface was well clogged.
[0068]
Next, the surface roughness of a cast product obtained by actual casting using these sand molds 1 to 3 was measured. The experiments were carried out using the sand molds 1 to 3 as they were (without coating) or by applying a coating agent by brush coating or spray coating. When the coating agent was applied with a brush, large irregularities formed by the brush marks were erased by applying and drying the coating agent and then tracing the surface with a soft cloth.
[0069]
The results are shown in FIG. As is clear from FIG. 5, the surface roughness was improved by applying the coating agent, and the brush coating was excellent as a coating method for the coating agent. As for the type of sand mold, the smoothness of the surface was improved in the order of sand mold 3> sand mold 2> sand mold 1.
[0070]
Next, in order to confirm the optimum blending ratio of the zircon flower, the sand mold was manufactured by changing the blending ratio of the zircon flower to Mikawa Silica No. 8, and the surface roughness of the casting surface was measured in the same manner, and the result is shown in FIG. This is shown in FIG.
[0071]
In FIG. 6, in the case where there is a coating agent, the coating agent is applied so as to have a thickness in the range of 20 μm to 100 μm. As a result, it was confirmed that the casting surface was improved by blending fine-grained foundry sand such as zircon flower with quartz sand as foundry sand. Moreover, the casting surface was improved in any case by the application of the coating agent.
[0072]
Although a sand mold was produced in which the amount of zircon flower blended in Mikawa Silica Sand No. 8 exceeded 60% by mass, this surface was rougher than sand mold 3. This is thought to be because the kneading machine used could not be sufficiently kneaded, but in any case, it is difficult to produce a sufficiently smooth surface with only excessively fine sand with high production efficiency. It seemed.
[0073]
From the above results, when a die casting method prototype that requires a smooth casting surface is required, it is necessary to use a sand mold formed by mixing fine powders such as zircon flowers at an appropriate ratio. It was well confirmed that the casting surface was further improved when a coating agent was applied to the sand mold.
[0074]
In this case, the maximum value of the particle size distribution is within the range of 100 mesh to 200 mesh (7 or 8 sand), preferably 150 mesh to 200 mesh (8 sand) and 300 mesh or less (fine powder). The foundry sand is contained within a range of 10% by mass to 60% by mass, particularly preferably 20% by mass to 50% by mass of the total casting sand, in which the proportion of fine particles (fine powder) of 350 mesh or less is included. It was confirmed that by using a more shaped sand mold, a prototype with an improved casting surface can be manufactured even by the low pressure casting method. Moreover, it was confirmed that there is an optimum value for the mixing ratio of the fine particles in this case.
[Example 2]
This Example 2 is an example for confirming that the sand-type low-pressure cast product used in the present invention can be effectively used as a prototype of a die-cast product with a substantial strength test. In any of the examples, the following experiment was performed using substantially the same apparatus as the manufacturing apparatus shown in FIG. 1 described above except that a sand mold cavity was used for the test piece.
[0075]
As die-cast prototypes, physical strength tests are often performed. Therefore, the die-cast prototype is required to have a physical strength comparable to that of a die-cast product that is mass-produced by an actual machine. Therefore, the following experiment was conducted using test pieces having thicknesses of 2, 4, and 6 mm using substantially the same apparatus as the manufacturing apparatus described above.
[0076]
Since the target values as prototypes of the die-cast product in this example are tensile strength: 200 MPa or more, 0.2% proof stress: 120 MPa or more, and elongation: 10% or more, the material for producing the prototype is fluid. Therefore, an AC4CH alloy capable of improving the characteristic value by heat treatment was used.
[0077]
When a cast product (F) was produced using substantially the same apparatus as the low-pressure cast product according to Example 1, none of the test pieces of any thickness satisfied the target value.
[0078]
Therefore, when heat treatment was performed under conditions of solution treatment 540 ° C. × 6 hours (water quenching) and aging 150 ° C. × 2 hours, it was confirmed that the target value was achieved by heat treatment in a test piece having a thickness of 4 mm or less. It was done.
[0079]
The above results are summarized in FIG. Here, the test piece which has not been heat-treated is denoted by reference symbol F, the test piece having only the solution treatment is denoted by symbol T4, and the test piece subjected to the solution treatment and the aging treatment is denoted by symbol T6.
[0080]
In the case where the wall thickness is 6 mm, the elongation falls below the target value when the solution treatment time is long. However, if the solution treatment time is set to 4 hours, the target value can be cleared. Thereby, it is considered that the target value can be achieved by changing the heat treatment conditions.
[0081]
From the above results, it is possible to produce a prototype that can withstand the substantial strength test even if the target is a die-cast product that requires the substantial strength test by heat-treating the obtained casting in the sand mold low pressure casting method. Is understood.
[Example 3]
This Example 3 is for demonstrating that a sand-type low-pressure cast product used in the present invention can have a shape substantially the same as that of a die-cast product. In this regard, in the present invention, since the purpose is to manufacture a prototype for obtaining a thin large casting, it is quantitatively understood whether or not the same shape can be obtained in the manufacturing method of the prototype according to the present invention. To do this, it is easy to grasp the flow length.
[0082]
Therefore, in this example, as shown in FIG. 8, an experiment was performed in which the flow length was measured using a sand mold formed from a fluidity test mold having a thickness of 1.5 mm, 2 mm, 4 mm, and 6 mm. . In order to demonstrate the superiority of the sand mold low pressure casting method according to the present invention, a sand mold gravity casting method was also tested as a control example.
[0083]
The results are summarized in FIG. In FIG. 9, the result abbreviated as ADP method is a result obtained by using substantially the same apparatus as the manufacturing apparatus shown in FIG. 1, and the sand-type low pressure casting method is the manufacturing apparatus shown in FIG. In this embodiment, the combustion is performed in an air atmosphere without supplying the combustion prevention gas or the oxidation prevention gas into the chamber 29.
[0084]
The sand type low pressure casting method has a flow length of about 250 mm when the wall thickness is 1.5 mm, and a flow length of 400 mm or more when the wall thickness is 2 mm, regardless of whether or not the oxide film is prevented. Thus, a flow length approximately twice as long was obtained.
[0085]
Thus, according to the sand mold low pressure casting method, it is possible to ensure a long flow length compared to the sand mold gravity casting method. It was confirmed that it was easy to manufacture a prototype with the same shape as the die-cast product.
[0086]
Further, according to the sand mold low pressure casting method, the thickness (t) is 4 mm or less, the length of one side is at least 200 mm or more, and the length (l) / thickness (t) is defined as 50 or more. It was confirmed that a cast product with substantial strength can be obtained by arranging a plurality (large number) of in-gates (faucets, gates) through which a prototype of such a thin large cast product leads to the cavity.
[0087]
Moreover, since the casting obtained by the above is formed from the aluminum alloy or the magnesium alloy which was excellent also in electromagnetic shielding property, the spread as prototypes, such as an electrical appliance and a motor vehicle part, is anticipated.
[0088]
【The invention's effect】
As described above, according to the present invention, in order to mass-produce thin large castings by the die casting method, the mass production mold is produced by the sand mold low pressure casting method from the design drawing of the die casting product. If a product is cast by using a material, and a mass production mold is manufactured based on the evaluation result of the prototype obtained by the casting prototype as an actual product, it is inexpensive and does not involve risk by using a die casting method. It is possible to produce a practically beneficial effect that a mass production mold for a large cast product can be manufactured.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an embodiment of the present invention.
FIG. 2 is an operation diagram of FIG. 1;
FIG. 3 shows the product obtained according to FIG.
FIG. 4 is another view showing the product obtained according to FIG. 1;
FIG. 5 is a diagram showing the result of measuring the surface roughness of a prototype obtained in an example.
FIG. 6 is a diagram showing the results of measuring the surface roughness of a prototype obtained in an example.
FIG. 7 is a diagram showing the results of measuring the tensile strength of a prototype obtained in an example.
FIG. 8 is a plan view for explaining a flow length test wood mold used in Examples.
FIG. 9 is a diagram showing a flow length test result.
[Explanation of symbols]
2 molten metal
3 crucible
11 Sand mold
16 cavities
17
21 Stoke
25 Thin large castings
28 Antioxidation gas or combustion prevention gas
29 chambers

Claims (9)

A method for producing a prototype for die casting, including a step of casting a prototype by a sand mold low pressure casting method in order to mass-produce a thin large casting by a die casting method ,
The sand mold low pressure casting method is:
It is a manufacturing equipment for thin large castings that applies pressure to the molten metal surface of the light metal stored in the crucible and pushes the molten metal into the sand mold cavity via stalk.
While having a narrow and long cavity for casting the thin large casting, the cavity is provided with a plurality of gates,
The stalk has a chamber capable of supplying an antioxidant gas or a combustion preventing gas in the middle,
The sand mold includes at least a lower mold that forms a cavity and an upper mold, and a sand mold (pouring mold) in which a gate or a runner that guides the molten metal to the cavity is formed between the lower mold and the stalk. A method for producing a prototype for die casting, characterized in that the sand mold uses a production apparatus for a thin large cast product to which a coating agent is applied .   The method for manufacturing a prototype for die casting, wherein the prototype is the same material as that in mass production or a different material.   2. The method for producing a prototype for die casting according to claim 1, wherein the sand mold is obtained by further applying a coating agent to a sand mold formed by mixing fine powder having a small particle diameter at an appropriate ratio. .   When the sand mold is sieved, it has a maximum value of the particle size distribution in the range of 100 mesh to 200 mesh and 300 mesh or less, and the proportion of fine particles of 350 mesh or less is 10 mass% or more of the total foundry sand 60 2. The method for producing a prototype for die casting according to claim 1, wherein a sand mold formed from casting sand contained within a mass% or less range is used.   The method for producing a prototype for die casting according to claim 4, wherein the coating agent is applied in a thickness range of 20 to 100 µm.   The die casting prototype manufacturing method according to claim 1, wherein the casting obtained by the low pressure casting method is further subjected to a heat treatment. The method for producing a prototype for die casting according to claim 1 , wherein the molten metal is aluminum or an aluminum alloy, and the antioxidant gas or the combustion preventing gas is an inert gas. Wherein the light metal melt, a magnesium or magnesium alloy, wherein the combustion preventing gas or the combustion preventing gas, characterized in that it is a mixed gas or equivalent gas of sulfur hexafluoride and carbon dioxide A manufacturing method of a prototype for die casting according to Item 1 . In producing a mass production mold from a design drawing of a die-cast product, at least one type of sand mold is produced according to the manufacturing apparatus for a thin large casting according to claim 1, and the die casting according to claim 1 is used by using the sand mold. casting the prototype of the same material or different materials and mass production at low pressure casting according to the manufacturing method of use prototype, that the prototype determines whether or not to enter the standard, to fabricate the production mold Prototype method for die-cast products.

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