低压铸和重力压铸
小鸟唱歌Low pressure casting and high pressure casting
低压铸造是液体金属在压力作用下充填型腔，以形成铸件的一种方法。由于所用的压力较低，所以叫做低压铸造。其工艺过程是：在密封的坩埚（或密封罐）中，通入干燥的压缩空气，金属液在气体压力的作用下，沿升液管上升，通过浇口平稳地进入型腔，并保持坩埚内液面上的气体压力，一直到铸件完全凝固为止。然后解除液面上的气体压力，使开液管中未凝固的金属液流坩埚，再由气缸开型并推出铸件。
Low pressure casting is a method of molten metal fills the cavity under the pressure and then forms the casting .due to the pressure is not high ,so it is called low pressure casting .The technical process is : in the hermetic crucible (or aled pot ) injecting the dry compresd air ,molten metal under the effect of gas pressure goes up along the pipe then through the gate placidly run into the cavity ,then keep the gas pressure upper the liquid in the crucible until the casting solidification totally .then remove the gas pressure to make the unfreezing metal in the pipe for opening run back into the crucible and at the same time us
e the cylinder open cavity to detrusion the casting .
低压铸造独特的优点表现在以下几个方面：心悸是怎么回事
The unique characteristics of low pressure casting performed as below :
1．液体金属充型比较平稳；
Molten metal full the cavity smoothly.
2．铸件成形性好，有利于形成轮廓清晰、表面光洁的铸件，对于大型薄壁铸件的成形更为有利；
The forming property is good and in favor of forming the edge shapeness and surface bright and clean .It is favorable for the large casting parts with thin ction casting
3．铸件组织致密，机械性能高；
The tissue of casting is densification ,and mechanical behavior is high .
4．提高了金属液的工艺收得率，一般情况下不需要冒口，使金属液的收得率大大提高，收得率一般可达大学生自我鉴定90％。
Improve the yield rate of the molten metal ,nomally don刘涛演过的电视剧’t need the dead head ,and make the yield rate a high improvement ,usually can achieve 90%.
此外，劳动条件好；设备简单，易实现机械化和自动化，也是低压铸造的突出优点。
in addition ,working condition is good ,equipments is not complicated and easy to reali mechanization and automation are also the highlight advantage .
重力铸造是指金属液在地球重力作用下注入铸型的工艺，也称浇铸。广义的重力铸造包括砂型浇铸、金属型浇铸、熔模铸造、消失模铸造，泥模铸造等；窄义的重力铸造专指金属型浇铸。
Gravity casting is that molten metal run in to the mould with the pressure of earth gravity ,it is also named pouring casting, generalized pouring casting incl. Sand casting ,metal mould casting ,investment casting ,evanescent mold casting and mud die casting ,ect. Narrowly pouring casting is the metal mould casting .
把金属材料做成所需制品的工艺方法很多，如铸造、锻造、挤压、轧制、拉延、冲压、切削、粉末冶金等等。其中，铸造是最基本、最常用的工艺。 足球知识手抄报
There are many ways to make the metal materials into the requested goods ,such as ,casting ,forging ,extrsion ,rolling ,madrelling ,punching ,cutting , powder metallurgy ,ect. Among them ,casting is the most basic and common technology
熔化的金属液注入用耐高温材料制作的中空铸型内，冷凝后得到预期形状的制品，这就是铸造。所得到的制品就是铸件。
The molten metal being injected into the medium altitude mould made by heat- resisting material ,then freezing to the shape as anticipated ,that is the process of the casting . and the freezing pasts is the casting.
铸造可按铸件的材料分为黑色金属铸造（包括铸铁、铸钢）和有色金属铸造（包括铝合金、铜合金、锌合金、镁合金等）。精密铸件厂专业从事有色金属铸造，重点是铝合金和锌合金铸造。
Casting can divide to black metal casting (incl. Cast iron, cast steel ) and nonferrous metals (incl. Aluminium alloy , copper alloy , zinc alloy , magnesium alloy ,ect.) .Precision
casting factory are specially engaged in nonferrous metal casting ,and aluminium alloy and zinc alloy are the emphasis .
按铸型的材料分为砂型铸造和金属型铸造。精密铸件厂对这两种铸造工艺都得心应手，并自行设计、制造这两类铸造模具。
According to the material ,casting can devide to sand mould casting and metal mould casting . Precision casting is facility with the two types of castings and design by themlves and produce the two typs moulds .
压力铸造是指金属液在其他外力（不含重力）作用下注入铸型的工艺。广义的压力铸造包括压铸机的压力铸造和真空铸造、低压铸造、离心铸造等；窄义的压力铸造专指压铸机的金属型压力铸造，简称压铸。
Pressure casting is pointed that molten metal run into the mould with the external force (excl. the gravity). Generized pressure casting include the die casting machine casting and vaccum casting ,low pressue casting ,centrifugal casting ,ect. And narrowly pressure
casting is specially pointed to metai mould casitng of the die casting machine. And for short is die casting .
浪花一朵朵歌曲
6李玲玉个人资料简介． 砂型铸造是一种以砂作为主要造型材料，制作铸型的传统铸造工艺。砂型一般采用重力铸造，有特殊要求时也可采用低压铸造、离心铸造等工艺。砂型铸造的适应性很广，小件、大件，简单件、复杂件，单件、大批量都可采用。砂型铸造用的模具，以前多用木材制作，通称木模。铝合金模具或树脂模具,然价格有所提高，但仍比金属型铸造用的模具便宜得多，在小批量及大件生产中，价格优势尤为突出。此外，砂型比金属型耐火度更高，因而如铜合金和黑色金属等熔点较高的材料也多采用这种工艺。但是，砂型铸造也有一些不足之处：因为每个砂质铸型只能浇注一次，获得铸件后铸型即损坏，必须重新造型，所以砂型铸造的生产效率较低；又因为砂的整体性质软而多孔，所以砂型铸造的铸件尺寸精度较低，表面也较粗糙。不过，精密铸件厂集多年的技术积累，已大大改善了砂型铸件的表面状况，其抛丸后的效果可与金属型铸件媲美。
sand mould casting is a foundry technology that using the sand as the material of the mould to make the mould , and usually sand casting u gravity casting ,and sometimes i
f have special requirements also adopt low pressue casting , centrifugal casting ,ect. Sand casting have a wide flexibility ,produce of small size parts ,large size parts ,plex one ,singleton,mass can all adopt. Sand casting ,previously sand casting u the wooden mould ,now u the aluminum alloy mould or resin mould ,the cost of aluminum alloy mould and resin mold are high than wooden mold ,but in the basss produce ,the advantage of cost stand out . sand mold has a better refractoness than metal mould . so cooper alloy and ferrous metal which metting point is high usually u this type technology, but sand casting has the shortage ,becau the mould can u only once .,after casting ,the mould is damaged .and need remake the new mould .the production efficiency is low , also the bulk property of sand is soft and porous , then the casting parts have a low precision and surface is rough . after years accumulation of technology ,the surface appearance have a good improvement ,and after shot blasting the surface appearance compare favourably with metal mould casting .
>国旗的由来
