阿里巴巴Pouring of investment castings
熔模铸件的浇注
The common pouring methods used in investment casting are:
熔模铸造时常用的浇注方法有：
1) Hot gravity casting
1）热型重力浇注
This is the most widely used form of casting, that is, the shell is removed from the furnace and poured at high temperatures.
这是用得最广泛的一种浇注形式，即型壳从焙烧炉中取出后，在高温下进行由浇注。
At this time, the metal is cooled slowly in the mold shell, and the mold can be filled in the case of high fluidity, so the casting can replicate the shape of the cavity well and improve the accuracy of the casting.
此时金属在型壳中冷却较慢，能在流动性较高的情况下充填铸型，故铸件能很好复制型腔的形状，提高了铸件的精度。
However, the slow cooling of the casting in the hot type will make the grain coarse, which reduces the mechanical properties of the casting.
但铸件在热型中的缓慢冷却会使晶粒粗大，这就降低了铸件的机械性能。
When pouring carbon steel castings, the surface of the castings that cool slowly is also easy to oxidize and decarburize, thereby reducing the surface hardness, finish and dimensional accuracy of the castings.
在浇注碳钢铸件时，冷却较慢的铸件表面还易氧化和脱碳，从而降低了铸件的表面硬度、光洁度和尺寸精度。
2) vacuum suction pouring
2）真空吸气浇注
The mold shell is placed in a vacuum pouring box, and the gas in the mold cavity is absorbed through the tiny pores in the mold shell, so that the liquid metal can better fill the mold cavity, copy the shape of the mold cavity, improve the casting accuracy, and prevent the defects of insufficient porosity and pouring.
将型壳放在真空浇注箱中，通过型壳中的微小孔隙吸走型腔中的气体，使液态金属能更好地充填型腔，复制型腔的形状，提高铸件精度，防止气孔、浇不足的缺陷。
The law has been applied abroad.
该法已在国外应用。
3) Crystallization under pressure
3）压力下结晶
The shell is placed in the pressure tank for pouring, after the end, the pressure tank is immediately closed, and high pressure air or inert gas is injected into the tank to make the casting solidify under pressure to increase the density of the casting.
将型壳放在压力罐内进行浇注，结束后，立即封闭压力罐，向罐内通入高压空气或惰性气体，使铸件在压力下凝固，以增大铸件的致密度。
The maximum pressure in foreign countries has reached 150atm.
在国外最大压力已达150atm。
4) Directional crystallization (directional solidification)
4）定向结晶（定向凝固）
Some investment castings such as turbine blades, magnetic steel, etc., if their crystalline structure is arranged in a certain direction of columnar crystals, their performance can be improved a lot, so investment casting directional crystallization technology is rapidly developing.
一些熔模铸件如涡轮机叶片、磁钢等，如果它们的结晶组织是按一定方向排列的柱状晶，它们的工作性能便可提高很多，所以熔模铸造定向结晶技术正迅速地得到发展。