How to improve the die casting mold process?
Die-casting machine, mold and alloy are based on , and the die-casting process runs through them, organically integrates them into an effective system, so that the die-casting machine and the mold can be well matched, and the structure of die-casting parts is optimized, preferably die-casting Machine, optimize the design of die-casting mold, and improve the flexibility of process working point, so as to provide reliable guarantee for die-casting production. Therefore, it is self-evident that the die-casting process is contained in the mold.
The position of the inner gate during die-casting affects the structural design, quality and design of the die-casting parts, and the prompt to correctly set the inner gate position can be obtained by querying the data. Due to the variety of casting structures, it is very difficult to choose the correct position of the inner gate, but there are also some basic requirements. For example, it is generally believed that the setting of the inner gate should make the metal jet during filling as free as possible in the cavity. It flows over a long distance, that is, the correct position, shape, and size (flow angle) of the inner gate are matched with the die-casting parameters to get the metal jet to expand and turn in an orderly manner along the mold wall, and continue to expand to the end. Most of the cavity (that is, the main cavity) is filled by jets, and only a small part of the cavity (that is, the non-main cavity) is filled by the branch of the metal melt or by the collision of the metal melt. The overflow system removes the residue.
The same chooses different inner gate positions and flow angles to obtain different main cavities, non-stem cavities and their respective percentages of area. When the shell is die-casted, due to the different positions of the internal gates, different results can be obtained. The main cavity and non-stem cavity. The gate is perpendicular to one side wall, because the rectangular hole at the top of the part separates the two side walls, the result is that only one side is the main cavity; to fill the other side wall, the two ends of the runner must be connected, and the last two strands The liquid flow converges to complete the filling, and this part is the non-main cavity. Because the area percentage of the main cavity is not high, a lot of waste will be generated.
The position of the inner gate is not changed, but the top rectangular hole is connected with a process rib of equal wall thickness, so that the molten metal turns during filling, and the other side wall is filled along the rib, so that both side walls become the main cavity. , The percentage of the main cavity is increased, and the quality of castings is also greatly improved. The top square hole does not add process ribs, but the inner gate is set at one end of the part, so that the metal melt is filled from both side walls at the same time, thereby expanding the percentage of the main cavity, ensuring the quality and improving the qualification rate. These are three types of internal gate settings for the same part, which proves the criticality of the internal gate position.
Although computer technology helps to select the location of the inner gate, computer technology is only a method, and the design of the inner gate position is still a key technology.
Based on castings, optimize the die-casting machine-mold-alloy system to improve process flexibility. In the die-casting machine-mold-alloy system, the quality and performance of die-casting parts can be improved by adjusting the process parameters. These process parameters are limited by a working window (OW). This shows that OW is the limit diagram of these process parameters. In the die-casting process, the filling time, the internal gate speed and the final metal static pressure are used to define the OW. These parameters are related to the filling phenomenon and depend on the mold design and the performance of the die-casting machine. During mold design, all points in OW are considered equal and have no priority. It can be considered that the best operating point exists at an unknown point in OW, which cannot be found before the die-casting mold is installed on the die-casting machine. its. In the mold design stage, ensuring that it is easy to find a good working point is based on the consideration of flexibility, which is obtained through adjustment in OW.
For this reason, the process parameters are divided into two types: soft parameters and hard parameters. Soft parameters refer to parameters that are adjusted by operation or a control device, such as power level, metal pressure, melt temperature, mold temperature, and cycle time. Hard parameters refer to a mold that needs to be corrected or a die-casting machine that needs to be corrected at the same time, such as punch diameter, gate area, exhaust groove, etc. Soft parameters are easy to change and succeed during mold trial, while hard parameters are difficult, costly, and time-consuming to change. It is often necessary to disassemble the mold for re-correction. Therefore, the optimization method is based on soft parameters and expands the flexibility of adjustment points in OW, thereby providing a larger range for mold testing and avoiding time-consuming and costly mold changes.
The mold temperature is one of the important process parameters. It can be said that the correct and constant mold temperature is the basic prerequisite for high-quality and reliable production, high productivity, low rejection rate and long mold life.
Before die-casting, the mold must be preheated to make the mold temperature reach 150-200℃, which is beneficial for coating, reducing melt temperature reduction and extending melt flow, which is beneficial to cavity filling. In addition, mold preheating can also increase mold material The toughness and reduce the thermal shock of the cavity surface. The best way to preheat the mold is to use hot oil to heat, with the help of a mold temperature machine to provide circulating hot oil and to control the mold temperature. If the machine is equipped with a device for quick loading and unloading of the mold, the mold can be preheated before installation, which can save the preheating time of the mold on the machine and speed up the start of the machine. At the same time, the mold temperature machine is also equipped with a circulating cooling water system to cool the mold as necessary. Gas heating is also a method. Natural gas or coal gas can be used depending on the factory conditions. In this case, the mold temperature can be measured with a surface thermometer and a temperature pen. Other heating methods include electricity and far infrared heating.