The process of extracting water glass precision castings from molds, removing excess external parts from the main body, and polishing the inner and outer surfaces of the castings.
Core removal and surface cleaning:
It is divided into two categories: dry method and wet method. Dry cleaning is the use of mechanical equipment to clean castings. The equipment used is simple, has high production efficiency, has great adaptability to different types of castings, and has the advantages of being able to remove the core and effectively clean the surface. The disadvantage is that the equipment often flies dust, produces high noise, and pollutes the environment during operation. Wet cleaning does not produce dust, but due to the use of water as a medium, the surface of castings is prone to rust and dirt. During the operation, a large amount of sewage and cement sand are generated, which brings problems such as sand and water regeneration and sludge treatment.
The commonly used dry and wet cleaning methods in production include:
① Drum cleaning. Put the casting and star iron together into the round drum. When the drum rotates, the collision and friction between the casting, star iron, and waste sand will remove the sand inside and outside the casting, and polish the surface of the casting. At the same time, it can also partially remove burrs and burrs, and this type of equipment is suitable for cleaning small and medium-sized castings with simpler shapes and thicker walls.
② Shot blasting cleaning. By utilizing the impact force of high-speed steel shot, iron shot, and abrasive flow, the core and sand are removed, and the surface of castings is polished. In addition, commonly used shot blasting cleaning equipment includes a shot blasting cleaning table and a shot blasting cleaning room. The shot blasting cleaning machines used for continuous production include chain plate shot blasting drums, continuous shot blasting cleaning tables, and suspended continuous production shot blasting cleaning rooms, which have high operating and maintenance costs.
③ Hydraulic sand cleaning. High pressure water is sprayed onto the treated casting through a pipeline from the nozzle, and the kinetic energy and scouring effect of the water flow are used to remove the core and casting sand sticking. Hydraulic sand cleaning is usually equipped with an open cleaning chamber composed of steel and steel plates, and a rotary worktable is set at the bottom. The spray gun is installed on the side wall, which can move up and down and rotate. High pressure water flow can be directed towards any part except the bottom of the casting. Sometimes, in order to improve the efficiency of removing sand sticking 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 pouring the mold, when the casting cools to the specified temperature, the box is opened and immediately immersed in a water pool. Water seeps into the mold through all gaps and rapidly vaporizes and explodes in contact with high-temperature metals. 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 operation time and high efficiency, and is widely used in Chinese steel casting workshops. It is generally used to treat steel castings with a carbon content below 0.35% and simpler shapes.
