Engaged in mechanical processing, high-precision mechanical parts manufacturing, the selection of blanks, Not only affects the economics of blank manufacturing, but also affects the economics of machining. Therefore, when determining the blank, it is necessary to consider the factors of thermal processing, but also the economic factors, but also the requirements of cold processing, in order to reduce the manufacturing cost of the parts from the determination of the blank.
precision metal products following, For example :
1. Castings : Blanks of parts with complex shapes should be manufactured by casting method. At present, most castings are sand-cast, which is divided into wood mold manual molding and metal mold machine modeling. The wood mold hand-molded casting has low precision, large processing surface and low production efficiency, and is suitable for single-piece small batch production or casting of large parts. The metal mold machine has high molding productivity and high casting precision, but the equipment cost is high, and the weight of the casting is also limited, which is suitable for small and medium-sized castings produced in large quantities. Secondly, small castings with high quality requirements can be cast in special castings such as pressure casting, centrifugal manufacturing and investment casting.
2. Forgings: steel parts with high mechanical strength requirements, generally used forging blanks. Forgings are available in both free forgings and die forgings. Free forging forgings can be obtained by hand forging (small blanks), mechanical hammer forging (medium blanks) or press forging (large blanks). The forgings have low precision, low productivity, large machining allowance, and the structure of the parts must be simple, suitable for single and small batch production, as well as for manufacturing large forgings. The precision and surface quality of die forgings are better than free forgings, and the shape of the forgings can be more complicated, thus reducing the machining allowance. Die forging is much more efficient than free forging, but requires special equipment and forging dies, so it is suitable for large and medium-sized forgings with large batch sizes.
3. Bending: profiles according to the cross-sectional shape can be divided into: round steel, square steel, hexagonal steel, flat steel, angle steel, channel steel, I-beam and other special sections of profiles. There are two types of profiles: hot rolling and cold drawing. Hot-rolled profiles have low precision, but are inexpensive, and are used for blanks of general parts; cold-drawn profiles are small in size, high in precision, easy to implement automatic feeding, but high in price, and are used for large batch production, suitable for automatic Machine tool processing.
4. Welded parts: Welded parts are joints obtained by welding. The advantages of welding are simple manufacturing, short cycle and material saving. The disadvantages are poor vibration resistance and large deformation, which can be machined after aging treatment. Reasonable use of machinery to manufacture precision parts of blanks not only saves material costs, but also saves a lot of processing time and improves production efficiency.