| 失蜡铸造的过程 |
| 添加时间：2018/11/7 10:16:52 浏览次数： |
| 将原模（一般是银版）用生硅胶包围，经加温加压产生硫化，压制成硅胶模；用锋利的刀片按一定顺序割开胶模后，取出银版，得到中空的胶模；向中空的胶模注腊，待液态的蜡凝固后打开胶模取出蜡模；对蜡模进行修整后将蜡模按一定排列方式种蜡树，放入钢制套筒中灌注高温石膏浆；石膏经抽真空、自然硬化、按一定升温时段烘干后，融化金属进行浇铸（可利用正压或负压的原理进行铸造）；金属冷却后将石膏模放入冷水炸洗，取出铸件后浸酸、清洗，剪下毛坯进行滚光；再进行执模和镶嵌、表面处理后即成为成品。上面提到的正压、负压铸造是指铸模内部在铸造过程中的压力状态而言。正压铸造以离心铸造为代表，在铸造过程中，熔融金属进入铸模时，铸模内的压力为大气压，这样要使液态金属进入铸模就必须使金属克服大气压的作用——离心铸造就是将液态金属坩埚与铸模安装在高速旋转的圆盘上，依靠离心力的作用使液态金属在圆盘的法向（径向）高速流动，产生注射作用进入铸模——也就是说，“正压铸造”过程中熔融金属进入铸模空腔的瞬间，铸模内部压力大于铸模外部压力，两者的差值大于0，故而称为“正压铸造”；“负压铸造”以真空吸铸为典型，在铸造过程中，熔融金属进入铸模时，铸模内部的压力小于铸模外部压力，两者的差值小于0，故而称为“负压铸造”——当然铸模内的负压必须通过与铸模连通的真空泵来完成，液态金属在大气压的作用下自然进入铸模。 The original mould (usually silver plate) is surrounded by raw silica gel, vulcanized by heating and pressure, and pressed into silica gel mould; after cutting the rubber mould with sharp blades in a certain order, the silver plate is taken out and the hollow rubber mould is obtained; the hollow rubber mould is waxed, and the wax mould is opened after the liquid wax solidifies; after the wax mould is repaired, the wax mould is removed. The wax mould is planted in a certain arrangement and poured into the steel sleeve with high-temperature gypsum slurry; the gypsum is vacuum-pumped, naturally hardened and dried at a certain heating period, then melted metal is cast (it can be cast by the principle of positive or negative pressure); after cooling, the gypsum mould is blasted and washed in cold water, and the castings are soaked after extraction. Acidic, cleaning, cutting off the blank for rolling, and then die-holding and mosaic, surface treatment will become finished products. The positive pressure and negative pressure casting mentioned above refers to the pressure state of the mold in the casting process. The positive pressure casting is represented by centrifugal casting. In the process of casting, when molten metal enters the casting mould, the pressure in the casting mould is atmospheric pressure. In order to make liquid metal enter the casting mould, the metal must overcome the effect of atmospheric pressure. Centrifugal casting is to install the liquid metal crucible and the casting mould on the high-speed rotating disc and depend on it. The effect of centrifugal force makes the liquid metal flow at high speed in the normal (radial) direction of the disc, and produces injection effect into the casting die. That is to say, when molten metal enters the cavity of the casting die in the process of "positive pressure casting", the internal pressure of the casting die is greater than the external pressure of the casting die, and the difference between the two is greater than 0, so it is called "positive pressure casting". "Negative pressure casting" takes vacuum suction casting as a typical example. In the process of casting, when molten metal enters the casting mould, the pressure inside the casting mould is less than the external pressure of the casting mould, and the difference between the two is less than 0, so it is called "negative pressure casting". Of course, the negative pressure in the casting mould must be completed by a vacuum pump connected with the casting mould, while the liquid metal is in the casting mould. It enters the mold naturally under the action of atmospheric pressure. |
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