In the automobile manufacturing process, there are many automobile parts made of cast iron, accounting for about 10% of the weight of the entire automobile, such as cylinder block, gearbox, steering gear housing, rear axle housing, brake drum, various brackets, etc.
Sand molding is usually used to make cast iron. The raw material of sand type is mainly sand, mixed with binder and water. Sand materials must have a certain bond strength in order to form the desired shape, resist the erosion of hot metal without collapse. In order to mold the cavity in the sand mold according to the shape of the casting, the mold needs to be made of wood, which is called a wood mold. Hot metal shrinks in volume as it cools. Therefore, the size of the wood mold needs to increase according to the shrinkage rate on the basis of the original size of the casting, and the surface to be machined will also be thicker accordingly.
Hollow castings need to be made into a sand core and the corresponding core wood mold (core box). With a wood mold, you can turn the cavity sand mold over (casting is also called "turning sand"). When making sand mold, it is necessary to consider how to separate the upper and lower sand boxes to remove the wood mold, the hot metal flows into the wood mold, and how to fill the cavity to obtain high-quality castings. After the sand mold is made, it can be poured, that is, the hot metal is poured into the cavity of the sand mold. When pouring, the hot metal temperature is 1250-1350℃, and the temperature is higher during melting.
Auto parts forging is widely used in automobile manufacturing. Forging is divided into free forging and die forging. Free forging is a process in which metal billets are placed on an anvil to withstand impact or pressure (called "blacksmithing"). The blanks of automobile gears and shafts are processed by the free forging method.
Die forging is a process in which metal blanks are placed into the cavity of the forging die and subjected to impact or pressure. Die forging is a bit like the process of dough being pressed into a cookie shape in a mold. Compared with free forging, the workpiece shape produced by die forging is more complex and the size is more accurate. Typical examples of automobile die forging parts are: engine connecting rod and crankshaft, automobile front axle, steering knuckle, etc.
thsi is forgings produced by tongxin precision forging company