De-coring and surface cleaning:
Divided into two types, dry and wet. Dry cleaning is the use of mechanical equipment to clean the castings. The equipment used is simple, the production efficiency is high, it has the advantages of greater adaptability to different types of castings and can remove the core and effectively clean the surface. The disadvantage is that the equipment is often dusty, noisy, and pollute the environment during operation. Wet cleaning has no dust, but because water is used as a medium, the surface of the investment casting is easy to rust. During the operation, a large amount of sewage and sand with cement are produced, which brings about the problems of sand and water regeneration and sludge treatment.
The dry and wet cleaning methods commonly used in production are:
①Drum cleaning. Put the castings and star iron into a round drum together. When the drum rotates, the inner and outer sand of the casting is removed by the impact and friction between the casting, star iron, and waste sand, and the surface of the casting is polished, and flash can also be partially removed. glitch. This type of equipment is suitable for cleaning small and medium-sized castings with simple shapes and thick walls.
② Shot blasting cleaning. The impact force of the high-speed moving steel shot, iron shot, and abrasive flow is used to remove the core, sticky sand, and polish the surface of the investment casting. In addition, the commonly used shot blasting equipment includes shot blasting table and shot blasting room. The shot blasting machine used for continuous production includes chain plate shot blasting drum, continuous shot blasting table, suspended continuous production shot blasting cleaning room, etc. The operation and maintenance costs of such equipment are relatively high.
③Hydraulic sand removal. The high-pressure water is shot from the nozzle of the spray gun to the processed casting through the pipeline, and the core and the casting sand are removed by the kinetic energy and scouring action of the water flow. Hydraulic sand cleaning is usually equipped with an open cleaning room composed of section steel and steel plate. The bottom is equipped with a rotary table. The spray gun is installed on the side wall, which can move up and down and rotate, so that high-pressure water can be sprayed to any part except the bottom of the casting. Sometimes in order to improve the efficiency of removing sticky sand on the surface of precision castings, abrasives such as quartz sand are introduced into the appropriate position of the spray gun to obtain high-speed water sand flow. This method is generally called water sand cleaning.
④ Water explosion to clear sand. After the investment casting mold is poured, the casting is boxed when it cools to the specified temperature, and it is immediately immersed in the pool. Water penetrates into the mold through all the gaps and contacts the high-temperature metal rapidly, vaporizes and explodes, and the shock wave can basically remove the sand attached to the inside and outside of the casting. The water explosion sand cleaning method has the advantages of short working time and high efficiency, and has been widely used in Chinese steel casting workshops. Generally used to process steel castings with a carbon content of less than 0.35% and simpler shapes.