JP2872322B2 - Vacuum casting method - Google Patents
Vacuum casting methodInfo
- Publication number
- JP2872322B2 JP2872322B2 JP888790A JP888790A JP2872322B2 JP 2872322 B2 JP2872322 B2 JP 2872322B2 JP 888790 A JP888790 A JP 888790A JP 888790 A JP888790 A JP 888790A JP 2872322 B2 JP2872322 B2 JP 2872322B2
- Authority
- JP
- Japan
- Prior art keywords
- molten metal
- casting
- mold
- degree
- pouring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は鋳造法に関し、特に薄肉鋳鋼品を製造するの
に適した減圧鋳造方法に関する。Description: TECHNICAL FIELD The present invention relates to a casting method, and more particularly to a vacuum casting method suitable for producing a thin cast steel product.
鋳鋼の溶湯は、粘度や鋳型砂に対する表面張力が大き
いこと、特に表面に生じ易い酸化膜の表面張力が大きい
ことなどが原因で、湯廻りが良くない。特に、薄肉のス
テンレス鋼鋳鋼品を製造する場合にこの欠点が顕著とな
り、健全な鋳物を製造することが困難である。The molten metal of cast steel has poor running ability due to its high viscosity and high surface tension against mold sand, and particularly high surface tension of an oxide film which tends to form on the surface. In particular, when a thin-walled stainless steel casting is manufactured, this defect becomes remarkable, and it is difficult to manufacture a sound casting.
この問題を解決する一手段として、ロストワックス鋳
造法などにおいて、鋳型を加熱することによって溶湯の
冷却を遅くし、湯流れを改善することがはかられてい
る。しかしその方法では、鋳型材料として高温強度の高
い特殊なものが必要となり、製造コストを高くしてい
る。As one means for solving this problem, in a lost wax casting method or the like, it has been attempted to slow down the cooling of the molten metal by heating a mold and improve the molten metal flow. However, this method requires a special material having high strength at high temperature as a mold material, which increases the manufacturing cost.
一方、鋳型内を減圧して大気圧を利用して溶湯を注入
する、いわゆる減圧鋳造方法があり、溶湯がキャビティ
のすみずみまで行きわたるので、薄肉鋳物に適する方法
として注目されている。従来の減圧鋳造方法において
は、鋳型内の空気を真空ポンプで吸引して予め減圧した
状態で注湯し、注湯中の減圧度は一定に保たれる。On the other hand, there is a so-called reduced pressure casting method in which a molten metal is poured using the atmospheric pressure by reducing the pressure in a mold, and the molten metal spreads to every corner of the cavity. In the conventional vacuum casting method, the air in the mold is sucked by a vacuum pump and poured in a state where the pressure has been reduced in advance, and the degree of vacuum during the pouring is kept constant.
しかしその方法では、第５図にグラフで示すように、
注湯の進行にともなって注入速度が激しく変動し、注入
溶湯の増加速度が一定せず、そのコントロールは困難で
あった。そのため溶湯が攪乱し、酸化物や気泡、夾雑物
等の生成が著しくなり、鋳造欠陥が生じ易かった。ま
た、減圧度を当初から高くするため、溶湯中に大気を吸
い込みやすいことも鋳造欠陥の発生原因になっていた。
その結果、製品の引張り強さ、伸び、断面収縮率等の特
性が劣化していた。However, in that method, as shown graphically in FIG.
The pouring speed fluctuated drastically as the pouring proceeded, and the increasing speed of the pouring molten metal was not constant, and it was difficult to control the pouring speed. For this reason, the molten metal was disturbed, and the generation of oxides, bubbles, impurities, and the like became remarkable, and casting defects were likely to occur. Further, since the degree of decompression is increased from the beginning, the air is easily sucked into the molten metal, which has also caused casting defects.
As a result, properties such as tensile strength, elongation, and cross-sectional shrinkage of the product were deteriorated.
従って本発明の目的は、鋳造欠陥が少なく、機械的特
性の優れた鋳物が得られる鋳造方法を提供することであ
る。Accordingly, an object of the present invention is to provide a casting method capable of obtaining a casting having few casting defects and excellent mechanical properties.
上記目的に鑑み鋭意研究の結果、本発明者は、減圧鋳
造を行う際に、減圧度を徐々に増大させれば、溶湯注入
速度が一定して、鋳造欠陥の少ない鋳物が得られること
を発見し、本発明を完成した。As a result of intensive research in view of the above object, the present inventor has found that, when performing vacuum casting, if the degree of vacuum is gradually increased, a molten metal injection speed is constant and a casting with few casting defects can be obtained. Thus, the present invention has been completed.
すなわち鋳物を減圧鋳造によって製造する本発明の方
法は、通気性鋳型を吸引ボックス内に収納し、注湯開始
直後から鋳型内を減圧し始め、注湯の進行に伴って減圧
度を増大させ、最終の減圧度ΔＰが次式： （ただし、σは金属溶湯の表面張力を表し、θは金属溶
湯と鋳型砂の接触角度を表し、Dpは鋳型砂の平均粒子径
を表す。）を満たすようにして、減圧することを特徴と
する。That is, the method of the present invention for producing a casting by vacuum casting is to store a gas permeable mold in a suction box, start depressurizing the mold immediately after pouring starts, and increase the degree of depressurization with the progress of pouring, The final pressure reduction degree ΔP is given by the following equation: (However, σ represents the surface tension of the molten metal, θ represents the contact angle between the molten metal and the foundry sand, and Dp represents the average particle diameter of the foundry sand.) I do.
以下、本発明の方法を、図面を参照して説明する。 Hereinafter, the method of the present invention will be described with reference to the drawings.
第１図に示すように、吸引ボックス１の底に砂２を敷
き、その上にコールドボックス、ペプセット型、CO
2型、セラミックシェル型あるいは焼結金型など、通気
性を有する鋳型３を収納する。次いで溶湯を湯口４から
キャビティ７内に注入し、それと同時に、吸引口６から
真空ポンプ（図示せず）等によって排気を開始する。0.
5〜２秒の間に減圧度を徐々に増し、最終的にはキャビ
ティ７内の圧力が−10〜−270g/cm2になるように調整す
る。As shown in FIG. 1, sand 2 is spread on the bottom of a suction box 1 and a cold box, a pepset type, a CO 2
A mold 3 having air permeability, such as a mold 2 , a ceramic shell mold or a sintered mold, is housed. Next, the molten metal is injected into the cavity 7 from the gate 4, and at the same time, evacuation is started from the suction port 6 by a vacuum pump (not shown) or the like. 0.
The degree of decompression is gradually increased in 5 to 2 seconds, and finally adjusted so that the pressure in the cavity 7 becomes −10 to −270 g / cm 2 .
それによって溶湯の注入速度が一定になるので、第６
図にグラフで示すように、注湯の進行にともなう注入溶
湯の増加速度が一定になり、溶湯は攪乱しない。そのた
め空気を巻き込まないので、酸化物や気泡、夾雑物等が
生成しにくく、鋳造欠陥の発生が防止される。減圧度
は、第６図に示すように段階的に増加させても、あるい
は連続的に増加させてもよい。減圧度は、吸引口６と真
空ポンプの間に減圧速度制御機を設置して制御する。As a result, the injection speed of the molten metal becomes constant.
As shown by the graph in the figure, the rate of increase of the injected molten metal with the progress of the molten metal becomes constant, and the molten metal is not disturbed. Therefore, since air is not entrained, oxides, bubbles, impurities, and the like are not easily generated, and the occurrence of casting defects is prevented. The degree of reduced pressure may be increased stepwise as shown in FIG. 6 or may be increased continuously. The degree of decompression is controlled by installing a decompression speed controller between the suction port 6 and the vacuum pump.
減圧度はキャビティ内での溶湯の流動性、ひいては製
品の鋳肌や仕上がり形状にも密接に関係する。種々の実
験を行った結果、金属溶湯の表面張力をσ（g/cm2）、
金属溶湯と鋳型砂粒子の濡れ即ち接触角度をθ（度）
（第２図参照、10:溶湯、20:鋳型砂）、鋳型砂の平均粒
子径をDp（cm）としたとき、最終的な（最大の）減圧度
ΔＰ（g/cm2）について、次式 を満たすようにするのが良いことがわかった。それによ
って望ましい仕上がり形状が得られ、鋳造欠陥も少なく
なる。The degree of decompression is closely related to the fluidity of the molten metal in the cavity, and also to the casting surface and finished shape of the product. As a result of various experiments, the surface tension of the molten metal was set to σ (g / cm 2 ),
The wetness of the molten metal and the mold sand particles, that is, the contact angle is θ (degree).
(See FIG. 2, 10: molten metal, 20: mold sand), when the average particle diameter of mold sand is Dp (cm), the final (maximum) degree of decompression ΔP (g / cm 2 ) is as follows. formula It turned out to be good to meet. This gives the desired finished shape and reduces casting defects.
第１図に示すように、溶湯を湯溜り８からそのままキ
ャビティ７に落す、いわゆる落し込み法で注湯すれば、
本発明の減圧鋳造による鋳込みは速くなる。しかし湯が
荒れやすいので、第３図に示すように、湯溜り８の下に
鉄板９を置くのが望ましい。注湯の開始時に溶湯が最も
攪乱しやすいが、鉄板９を置くと、湯溜り８で溶湯の流
動が少なくなるとともに酸化物等が上に浮いた後、鉄板
９が溶けて溶湯がキャビティ内に流れ込む。それによっ
て鋳造欠陥の発生がより一層防止される。鉄板は、0.1
〜0.3mmの厚さで鋳物と同材質のものがよい。As shown in FIG. 1, if the molten metal is dropped from the pool 8 into the cavity 7 as it is,
The casting by the vacuum casting of the present invention is faster. However, since the hot water tends to be rough, it is desirable to place an iron plate 9 under the well 8 as shown in FIG. The molten metal is most easily disturbed at the start of pouring. However, when the iron plate 9 is placed, the flow of the molten metal in the pool 8 is reduced, and after the oxides and the like float up, the iron plate 9 is melted and the molten metal enters the cavity. Flow in. Thereby, the occurrence of casting defects is further prevented. The iron plate is 0.1
Thickness of ~ 0.3mm and the same material as the casting is preferred.
実施例１ 第１表に示すステンレス鋼成分の溶湯を大気中で溶解
し、1550℃に保持した。吸引ボックスの中にコールドボ
ックス型を収納するとともに、湯溜りの中に上記ステン
レス鋼と同材質で厚さ0.2mmの鋼板を置いた。取鍋から
落し込み注湯すると同時に、ロータリー式真空ポンプで
鋳型内の空気の吸引を開始した。2.7lの溶湯を注入する
間、徐々に段階的に減圧度を上げ、注湯完了時の減圧度
を270g/cm2とした。冷却後、第４図に示すエギゾースト
マニホールド30を得た。Example 1 A melt of a stainless steel component shown in Table 1 was melted in the air and kept at 1550 ° C. The cold box type was housed in the suction box, and a steel plate having the same material as the stainless steel and having a thickness of 0.2 mm was placed in the water pool. At the same time as dropping and pouring from the ladle, suction of air in the mold was started with a rotary vacuum pump. During the injection of 2.7 l of molten metal, the degree of decompression was gradually increased, and the degree of decompression upon completion of pouring was 270 g / cm 2 . After cooling, an exhaust manifold 30 shown in FIG. 4 was obtained.
製品30には表面欠陥、内部欠陥とも認められなかっ
た。また、製品30から採取したテストピースの機械的性
質は下記の通りであった。 In the product 30, neither surface defects nor internal defects were recognized. The mechanical properties of the test pieces collected from the product 30 were as follows.
引張り強さ 65 kgf/mm2 耐力 40 kgf/mm2 伸び 23 ％ 絞り 45 ％ 硬さ 174 HB 比較例１ 減圧過程以外は実施例１と同様の方法で、同材質のエ
ギゾーストマニホールド30を減圧鋳造によって製造し
た。Tensile strength 65 kgf / mm 2 Proof strength 40 kgf / mm 2 Elongation 23% Draw-down 45% Hardness 174 HB Comparative example 1 Exhaust manifold 30 of the same material is vacuum-cast by the same method as in Example 1 except for the pressure-reducing process. Manufactured.
注湯前から80mmHg減圧し、注湯を完了するまで減圧度
を一定に保った。The pressure was reduced by 80 mmHg before pouring, and the pressure was kept constant until pouring was completed.
製品30の内部に若干の巣不良が認められた。また、製
品30から採取したテストピースの機械的性質は下記の通
りであった。Some nest defects were found inside the product 30. The mechanical properties of the test pieces collected from the product 30 were as follows.
引張り強さ 61 kgf/mm2 耐力 38 kgf/mm2 伸び 20 ％ 絞り 45 ％ 硬さ 174 HB 〔発明の効果〕 以上述べた通り、本発明の方法においては、減圧鋳造
を行う際に減圧度を徐々に増大させるので、注入溶湯が
攪乱しにくく、空気の巻き込みが少ない。従って、酸化
物や気泡、夾雑物等の鋳造欠陥の少ない鋳物を得ること
ができる。Tensile strength 61 kgf / mm 2 Yield strength 38 kgf / mm 2 Elongation 20% Draw-down 45% Hardness 174 HB [Effect of the invention] As described above, in the method of the present invention, the degree of decompression is reduced when performing vacuum casting. Since it is gradually increased, the molten metal is less likely to be disturbed and air entrapment is reduced. Therefore, a casting with few casting defects such as oxides, bubbles, impurities, and the like can be obtained.
第１図は本発明の方法において用いられる鋳造装置の縦
断面図であり、 第２図は溶湯と鋳型砂の接触角度を説明する拡大断面図
であり、 第３図は第１図の装置の変形例を示す部分拡大断面図で
あり、 第４図はエギゾーストマニホールドの概略図であり、 第５図は従来の減圧鋳造方法における鋳込み時間、減圧
度及び注入溶湯量の関係を示すグラフであり、 第６図は本発明の減圧鋳造方法における鋳込み時間、減
圧度及び注入溶湯量の関係を示すグラフである。 １……吸引ボックス ２……砂 ３……鋳型 ４……湯口 ６……吸引口 ７……キャビティ ８……湯溜り ９……鉄板 10……溶湯 20……鋳型砂 30……製品（エギゾーストマニホールド）FIG. 1 is a longitudinal sectional view of a casting apparatus used in the method of the present invention, FIG. 2 is an enlarged sectional view illustrating a contact angle between molten metal and mold sand, and FIG. 3 is an apparatus of FIG. FIG. 4 is a partial enlarged cross-sectional view showing a modified example, FIG. 4 is a schematic view of an exhaust manifold, and FIG. 5 is a graph showing a relationship between a casting time, a degree of pressure reduction, and an amount of molten metal in a conventional vacuum casting method; FIG. 6 is a graph showing the relationship between the casting time, the degree of pressure reduction and the amount of molten metal in the vacuum casting method of the present invention. 1 ... Suction box 2 ... Sand 3 ... Mold 4 ... Sluice 6 ... Suction port 7 ... Cavity 8 ... Hot water 9 ... Iron plate 10 ... Melt 20 ... Mold sand 30 ... Product (exhaust) Manifold)
フロントページの続き (56)参考文献 特開 昭61−78550（ＪＰ，Ａ) 特開 昭61−99553（ＪＰ，Ａ) 特開 昭62−3861（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) B22D 18/06,18/08 (56) References JP-A-61-78550 (JP, A) JP-A-61-99553 (JP, A) JP-A-62-3861 (JP, A) (58) Fields studied (Int) .Cl. 6 , DB name) B22D 18 / 06,18 / 08
Claims (1)
いて、通気性鋳型を吸引ボックス内に収納し、注湯開始
直後から鋳型内を減圧し始め、注湯の進行に伴って減圧
度を増大させ、最終の減圧度ΔＰが次式： （ただし、σは金属溶湯の表面張力を表し、θは金属溶
湯と鋳型砂の接触角度を表し、Dpは鋳型砂の平均粒子径
を表す。）を満たすようにして、減圧することを特徴と
する方法。In a method of manufacturing a casting by vacuum casting, a gas-permeable mold is housed in a suction box, and the pressure inside the mold is reduced immediately after the start of pouring, and the degree of vacuum is increased as the pouring proceeds. , And the final pressure reduction degree ΔP is given by the following equation: (However, σ represents the surface tension of the molten metal, θ represents the contact angle between the molten metal and the foundry sand, and Dp represents the average particle diameter of the foundry sand.) how to.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP888790A JP2872322B2 (en) | 1990-01-18 | 1990-01-18 | Vacuum casting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP888790A JP2872322B2 (en) | 1990-01-18 | 1990-01-18 | Vacuum casting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03216257A JPH03216257A (en) | 1991-09-24 |
| JP2872322B2 true JP2872322B2 (en) | 1999-03-17 |
Family
ID=11705192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP888790A Expired - Lifetime JP2872322B2 (en) | 1990-01-18 | 1990-01-18 | Vacuum casting method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2872322B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4524691B2 (en) * | 2007-06-07 | 2010-08-18 | 新東工業株式会社 | Mold decompression method |
| JP2014039936A (en) * | 2012-08-21 | 2014-03-06 | Dia Shinku Kk | Hearth member, and cooled and solidified metal manufacturing device using the hearth member |
-
1990
- 1990-01-18 JP JP888790A patent/JP2872322B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03216257A (en) | 1991-09-24 |
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