Dalian castings should avoid large horizontal surface, because it makes the molten metal rise very slowly during casting, and the surface in contact with the air is large, which is easy to oxidize. At the same time, due to the rapid heat dissipation of the metal mold, the molten metal quickly loses its fluidity, which is easy to cause defects such as insufficient pouring, cold insulation, slag inclusion, etc; When designing metal mold castings with complex shapes, if there are great difficulties in the production process, try to make the shape of the castings simple and change the strong structure without affecting the service conditions of the castings, so as to facilitate the removal of the castings from the metal mold.
The quality, productivity and cost of castings are greatly affected by ensuring their working performance and mechanical property requirements, considering the requirements of casting process and alloy casting performance on the casting structure, and whether the casting structure design is reasonable or not. Meet the strength and stiffness requirements. It is an important problem to meet the strength of box parts with great stress; But for most cases, the main index to evaluate the performance is stiffness, because the stiffness of the case not only affects the normal operation of the transmission parts, but also affects the working accuracy of the components. The automatic model selection of castings is included. The structural design is reasonable. For example, the arrangement of fulcrum, the arrangement of reinforcement, the location of opening and the design of connecting structure should be conducive to improving the strength and stiffness of the box.
The cost of castings and forgings in Dalian is high and the production cycle is long. The processing of forged parts can ensure the continuity of metal fiber structure, keep the fiber structure of forgings consistent with the shape of forgings, complete metal streamline, dense structure and good mechanical properties. It can ensure that the objects have good mechanical properties and long service life. The processed objects are sharp and durable, with high strength and first-class texture. The groove and scar defects formed on the surface of the casting are easy to occur when using the wet mold to cast thick and large flat castings.
Most of the parts with sand inclusion in the casting are in contact with the upper surface of the sand mold. The upper surface of the mold cavity is easily arched and warped due to the radiant heat of the metal liquid. When the warped sand layer is continuously scoured by the metal liquid flow, it may break and be left in place or brought into other parts. The larger the upper surface of the casting, the larger the volume expansion of the molding sand, and the greater the tendency to form sand inclusions.
Solutions to defects of castings in Dalian: casting defects, such as air holes, shrinkage cavities, sand holes, sand sticking and cracks, have always been unavoidable and difficult to solve in the casting industry. The conventional method for repairing unqualified castings is mainly welding repair, which requires skilled workers, takes time and consumes a lot of materials. Sometimes, due to the influence of component materials, welding will also lead to increased damage, resulting in component scrap, which increases the production cost of enterprise equipment.
