Die design manual has been introduced in detail die casting mold design should pay attention to the issue, but in determining the injection speed, the maximum speed should not exceed 100m / s. Too high speed, prompting mold corrosion and the cavity and the core deposits increased; but too low to make casting defects. Therefore, for magnesium, aluminum, zinc corresponding minimum injection velocity of 27,18,12 m / s, the maximum casting aluminum casting speed should not exceed 53m / s, the average injection rate of 43m / s.
In the process of processing, the thicker template can not be stacked to ensure its thickness. Because the thickness of the steel is 1 time, the amount of bending deformation is reduced by 85%. The stacking can only act as a superposition. The bending deformation of the two boards with the same thickness as the board is four times that of the single board. In addition, when processing cooling waterways, both sides should pay special attention to ensure concentricity. If the corners of the head are not concentric with each other, then the corners of the connection will crack during use. The surface of the cooling system should be smooth, preferably without leaving traces of machining.
EDM is more and more widely used in the processing of mold cavity, but the hardened layer remains on the surface of the processed cavity. This is due to processing, the mold surface caused by carburizing and quenching. The thickness of the hardened layer is determined by the current intensity and the frequency during processing, which is deep during roughing and shallower when finishing. No matter shades, the mold surface has great stress. If you do not remove the hardened layer or eliminate stress, in the course of use, the mold surface will produce cracking, pitting and cracking. Elimination of hardened layer or stress available: ① with whetstone or grinding to remove hardened layer; ② without reducing the hardness of the case, lower than the tempering temperature stress, which can significantly reduce the cavity surface stress.
Mold in the use of the process should be strictly controlled casting process. Within the process permit, try to reduce the aluminum casting temperature, injection speed, increase the mold preheat temperature. Aluminum die-casting mold preheating temperature from 100 ~ 130 ℃ increased to 180 ~ 200 ℃, mold life can be greatly improved.
Welding repair is a common tool in mold repair. Before welding, should master the type of mold steel, mechanical machining or grinding to eliminate surface defects, the welding surface must be clean and dried. The electrode used should be consistent with the mold steel composition, it must be clean and dried. The mold and the electrode are preheated together (H13 is 450 ℃), until the surface and the heart temperature are the same, the welding is repaired under the protective gas. In the welding process, when the temperature is below 260 ℃, to reheat. After welding, when the mold is cooled to the hand touches, then heated to 475 ℃, 25mm / h insulation. Finally in the still air completely cooled, and then the cavity finishing and finishing. Die welding after heating and tempering, welding repair is an important part of the elimination of welding stress and the welding is heated and quenched under the layer of the weld layer tempering.
Mold used for some time, due to the injection speed is too high and prolonged use, the cavity and the core will have sediment. These deposits by the release agent, coolant impurities and a small amount of die-cast metal at high temperature and pressure combined.