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铸件质量与气孔的关系

网址:www.zaoxingji.com.cn  2020-05-13  作者:admin    阅读:

铸件质量与气孔的关系
Relationship between casting quality and porosity
气孔的特征: 多位于表面附近,尺寸较大,呈椭圆形或梨形孔的内表面被氧化。
Characteristics of stomata: most of them are near the surface, with large size, and the inner surface of oval or pear shaped pores is oxidized.
气孔形成过程:
Pore formation process:
浇注---水汽(一部分由分型面,通气孔排出,另一部分在表面聚集呈高压中心点)—气压升高,溶入金属---一部分从金属液中逸出—浇口,其余在铸件内部,形成气孔。
Pouring - water vapor (one part is discharged from the parting surface and the vent hole, the other part is gathered on the surface as a high-pressure center point) - the air pressure rises and dissolves into the metal - one part escapes from the molten metal - gate, the rest is in the casting, forming the air hole.
预防气孔的发生: 降低型砂(型芯砂)的发起量,增加铸型排气能力。
Prevent the occurrence of porosity: reduce the amount of molding sand (core sand) and increase the ability of mold exhaust.
析出气孔: 溶于金属液中的气体在冷凝过程中,因气体溶解度下降而析出,使铸件形成气孔,原因: 金属熔化和浇注中与气体接触(H2 O2 NO CO等) 特征: 分布广,气孔尺寸甚小,影响气密性。
Precipitated porosity: during the condensation process of gas dissolved in liquid metal, the gas will be precipitated due to the decrease of gas solubility, which will cause the formation of porosity in the casting. The reason: metal melting and gas contact during pouring (H 2O 2No Co, etc.) feature: wide distribution, very small pore size, affecting air tightness.
反应气孔: 金属液与铸型材料,型芯撑,冷铁或溶渣之间,因化学反应生成的气体而形成的气孔。如: 冷铁有锈 Fe3O4 + C –Fe + CO 冷铁附近生成气孔防止: 冷铁型芯撑表面不得有锈蚀,油污,要干燥。
Reaction pore: the pore formed by gas generated by chemical reaction between molten metal and casting material, core support, cold iron or slag. For example: there is rust in cold iron, and pores are formed near Fe3O4 + C – Fe + CO cold iron to prevent: the surface of cold iron core support shall be free of rust, oil stain and dry.

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