The structure of the casting should not only be conducive to ensuring the quality of the casting, but also take into account the convenience of pattern manufacturing, modeling, core making and cleaning operations, so as to simplify the manufacturing process, stabilize product quality, improve productivity and reduce costs. Its basic requirements are as follows:
(1) Simplify or reduce the parting surface of the casting structure.
(2) reduce the number of sand cores of the casting structure, the inner cavity of the casting is generally formed with sand core, which increases the core making hours and process equipment, and complicates the mold assembly and increases the cleaning workload of the casting. Therefore, the structure of the casting should try not to use sand core or less.
(3) The structure of the casting is reasonable to design the boss, rib, groove, etc., which can facilitate the mold drawing and reduce the damage of the sand mold.
(4) Casting structure conducive to the fixing and exhaust of the sand core In order to ensure the dimensional accuracy of the casting and prevent casting defects such as eccentric core and porosity, the structure of the casting should be conducive to the fixing and exhaust of the sand core. The design structure of cantilever sand core, hanging core and using core support should be avoided as far as possible.
(5) Casting with casting process holes Casting structure with a closed shape or semi-closed shape cavity, to design a casting process hole. Its role is to support the sand core to form an inner cavity, to facilitate the sand core exhaust and to facilitate the chain, lifting and sand cleaning.
(6) The cleaning work of castings is conducive to the cleaning of castings. The cleaning work of castings includes sand cleaning, cutting and pouring, removing wings and burr, grinding and dressing, correcting deformation and repairing defects. This part of the workload is very large, the working conditions are poor. Therefore, the structural design of the casting should be as convenient as possible for the cleaning of the casting.
(7) Casting structure that is conducive to meeting the dimensional tolerance of the casting Because the casting of the sand casting has a wide dimensional tolerance zone, the structure and size design of the casting, only taking into account the dimensional tolerance of the casting in the casting, will not make the production of the casting in mechanical properties and size can not meet the requirements of the design pattern.
(8) Assembly gap between castings and other parts When assembling castings with other parts, the design gap between the casting surface and its adjacent parts should be selected with reference to in addition to considering the casting size tolerance zone, so as not to hinder the assembly due to the deviation of the casting size.
(9) In order to facilitate the cutting of the corner part, the tool return groove is often designed on the structure of the part. When designing the retracting slot, the machining allowance should be taken into account to make the slot have a certain width. If the retracting slot is narrow, it is easy to produce sticky sand. When the sticky sand can not be completely removed, it is easy to damage the tool during cutting.
