14.1 Flat cover

Flat cover refers to the head or cover plate with a flat surface of the shell. When used as the head, it is also called "flat head", and when used as the bottom head, it is also called "flat bottom". The geometric shapes are round, oval, oblong and rectangular. After being subjected to pressure, the bending stress is mainly generated in the flat cover, and the joint of the flat cover and other shells produces a large discontinuous stress due to the sudden change of geometric shape, so the thickness required by the flat cover is larger than that required by other shaped heads in the case of the same diameter and jade.

The advantages are simple structure and convenient manufacture. The disadvantage is that the mechanical properties are poor, the material consumption is large and bulky. Suitable for normal pressure, low pressure or small diameter high pressure occasions. In addition to direct welding with other shells, there are also detachable connections using bolts, such as manhole covers and hand hole covers.

The control of die casting mold surface temperature is very important for the production of high-quality die casting parts. Uneven or inappropriate mold temperature will also lead to casting size instability, ejecting casting deformation during the production process, resulting in thermal pressure, sticky mold, surface depression, internal shrinkage holes and hot bubbles and other defects. When the mold temperature difference is large, it has different degrees of influence on the variables in the production cycle, such as filling time, cooling time and spraying time.