The characteristics of the whole mold modeling method are: the shape is integral, the cavity is all located in a sand box, and the parting surface is flat. Figure 3 shows the basic process of the overall mold modeling of the bearing seat casting. The whole mold modeling method is easy to operate, and the mold cavity shape and dimensional accuracy are good, so it is suitable for castings with simple shapes and the largest cross section at one end, such as simple castings such as gear blanks, pulleys, and bearing seats, suitable for various batches produce.
The characteristics of the parting modeling method are: the pattern is divided into two halves at the largest section, and the two halves are positioned with positioning pins when they are closed. The plane where the two halves are separated (ie, the parting surface) is often the parting surface during modeling. When modeling, the two halves are carried out in the upper and lower sand boxes respectively. This modelling method is suitable for castings with complex shapes with the largest cross section in the middle, especially for castings with holes, such as sleeves, pipes, crankshafts, columns, valve bodies, boxes, etc. Because of its convenient operation, it is widely used. Figure 4 shows the basic process of split-mold modeling of water pipe castings.
If the contour of the casting is a curved surface or a stepped surface, its maximum cross-section is also a curved surface, and the appearance is not easy to divide into two halves. At this time, the sand-digging method is commonly used. This method is suitable for single-piece small batch production. If the production batch is large, the fake box molding method can be used.
When digging sand for modeling, the parting surface needs to be dug and repaired, and the parting surface must be dug and repaired to the largest section of the pattern. The parting surface should be dug and repaired as smoothly as possible. Sand excavation is required for each mold, which is troublesome in operation, low in production efficiency, and requires high technical level of the operator. Burrs are prone to occur at the parting surface of the casting, and the appearance and accuracy of the casting are poor.