Compared with the traditional wood mold turning process, the mold size and size are limited by the table size and accuracy of the rapid prototyping machine, and the manufacturing cost is high, so it is not suitable for the manufacturing of large and complex castings. Combined with the above problems, this paper combines CAD design, material addition manufacturing, material reduction manufacturing and sand mold casting methods, and comprehensively uses two sand mold (core) dieless manufacturing technologies to realize the direct forming of sand mold sand core for complex casting of tractor, which is cast after assembly.
After the sand core of sand mold is formed, it needs to be mold closed and cast. The figure shows the mold closing process of a product. The specific methods are as follows.
(1) During the mold closing process, the sand mold, sand core and split movable block shall be bonded with sand core adhesive according to the drawing, and the movable block with small bonding area shall be fixed with steel nails.
(2) Before closing the box, further shape and chamfer for pre assembly. The wall thickness shall be tested with cement strips. It is required that the wall thickness error of complex parts of tractor castings meet the drawing and process requirements. Finally, brush the sand mold (core) with paint, dry it and close the box.
(3) Due to the large size of shell parts, it is generally necessary to heighten the pouring riser. The castings of complex parts of tractors above 100 kg (including pouring riser) are sleeved with a sand box after molding, and solidified after filling the back sand.
(4) Pressed iron, melting and pouring.
(5) After closed box pouring, after the castings of complex parts of the tractor are cooled, the castings of complex parts of the tractor are boxed and cleaned, the pouring riser is removed, polished and cleaned, and shot blasting is carried out to obtain the blank parts. The blank can be delivered for use after being processed according to the drawing.