Magnesium aluminum alloy die-casting mold temperature machine

Due to the sensitivity of the casting properties such as fluidity of magnesium aluminum alloys to mold temperature and pouring temperature, during the filling process,Magnesium aluminumAlloy liquid is prone to solidification, so in order to ensure the surface and internal quality of magnesium alloy die-casting parts, reduce the scrap rate of die-casting production, improve the productivity of die-casting, and increase the service life of die-casting molds, it is necessary to accurately control the temperature of die-casting molds. To meetMagnesium aluminumThe need for alloy die-casting processing,XingdeDeveloped equipment for temperature control of die-casting molds-Magnesium aluminum alloy die-casting mold temperature machine.

Temperature is a thermal factor in the die-casting process. To ensure the forming quality of die-casting parts, control and maintain thermal stability, corresponding temperature specifications must be selected, mainly referring to the casting temperature of the alloy and the mold temperature. InMagnesium aluminumIn die casting of alloys, the ideal heating method is to use a mold temperature machine or oil heater to heat the mold with hot oil. The hot oil continuously passes through the pipes inside the mold and heats the mold from the inside to achieve a stable equilibrium state. Due to their ability to not only heat but also cool the mold like water, the oil mold temperature machine and heat transfer oil furnace function like heat exchangers, maintaining the mold temperature within a certain range.
Magnesium aluminumThe heating method of the alloy die-casting mold temperature machine ensures stable and uniform temperature of the mold, which can effectively extend the life of the mold, improve product quality, and stabilize the production cycle.Magnesium aluminumThe temperature of the mold during alloy die-casting is generally maintained between 180 ℃ and 280 ℃.
Application of Magnesium Aluminum Alloy Die Casting Mold Temperature Machine
1、 Requirements for Control Function of Magnesium Aluminum Alloy Die Casting Mold Temperature Machine
InMagnesium aluminumIn the production of alloy die-casting, according to its production characteristics, the temperature control of die-casting molds includes two aspects: preheating and cooling of the molds. The temperature is related to the material of the die-casting and also to the size of the die-casting part. Generally, it is about one-third of the pouring temperatureMagnesium aluminumAlloy, usually at 180-280 ℃. In addition, during the preheating process, it is advisable to evenly heat all parts of the mold to avoid the adverse effects of severe heating and local overheating on the service life of the mold.
In general, the heat absorbed by the mold is greater than the natural heat dissipation, so as the die-casting production progresses, the temperature of the mold will become higher and higher. In order to carry out normal die-casting production, it is necessary to maintain a basically constant temperature of the mold. Generally, the mold is cooled by opening a cooling water channel and passing cooling water through it. As mentioned above, in order to achieve constant temperature control for preheating and cooling the mold, a guide can be usedMagnesium aluminumThe die-casting dedicated mold temperature machine controls the temperature of the mold, and the heat transfer oil continuously passes through the internal pipeline of the mold to heat or cool the mold from the inside, maintaining a certain temperature and in a suitable production state.
IIMagnesium aluminumPrinciple of Temperature Control for Die Casting Special Mold Temperature Machine
Magnesium aluminumThe dedicated die temperature machine for alloy die-casting adopts heat transfer oil circulation temperature control. When the heat transfer oil circulates in the cooling channel of the mold, there is heat transfer between the heat transfer oil and the mold channel wall (mold) due to the temperature difference between them. The heat exchange rate is related to factors such as the thermodynamic properties of the heat transfer oil, the cross-sectional area of the mold channel, the flow rate of the heat transfer oil, the oil temperature, and the mold temperature.
After determining the type of heat transfer oil and the cross-sectional area of the mold channel, the heat exchange rate can be calculated using Newton's cooling formula
Calculate using the formula of φ=Ah (Tm Tf),
Among them, φ is the heat flow rate of the system, A is the heat exchange surface area, Tm is the mold temperature, Tf is the temperature of the heat transfer oil, and h is the average surface heat transfer coefficient of the fluid channels inside the mold, which is related to the flow rate of the heat transfer oil.
Due to the determined cross-sectional area of the mold channel, the flow rate of the heat transfer oil can be determined by calculating the flow rate of the heat transfer oil. The heat exchange capacity of the system can be expressed by the following functional relationship: φ=f (q, Tm, Tf), where q is the flow rate of the heat transfer oil, m³/s。
The mold temperature Tm is a controlled quantity, and it is hoped to remain constant, that is, Tm is basically a constant. Therefore, as long as the flow rate q of the heat transfer oil or the temperature Tf of the heat transfer oil are controlled within a certain range, the heat exchange between them can be controlled, thereby controlling the heating and cooling of the mold, and thus controlling the temperature of the mold. For the convenience of control, the method of adjusting the temperature of the heat transfer oil by fixing the flow rate of the heat transfer oil can be used, so that as long as the temperature of the heat transfer oil is controlled well, the temperature of the die-casting mold can be controlled. The principle of the thermal oil circulation system of the mold temperature controller is shown in the diagram.
The heat exchange channel of the mold, together with the circulating oil pump, valve, pipeline, heater, cooler and other components of the mold temperature control machine, forms a complete thermal oil circulation path. Except for the mold, all other components are insulated and heat-treated. The high-temperature oil pump sucks the heat transfer oil into the circulation path, and the control system of the magnesium aluminum alloy die-casting mold temperature machine controls the heat transfer oil to circulate at the required temperature. When the oil temperature is lower than the set temperature, the system heats the heat transfer oil and raises the oil temperature to the set temperature; When the oil temperature is higher than the set temperature, open the cooling water control solenoid valve to reduce the oil temperature to the set temperature.

3、 Magnesium aluminumAlloy die-casting mold temperature machineSelection and Design of Components
The key purchased component in the magnesium aluminum alloy die-casting mold temperature machine is the high-temperature heat transfer oil pump. The basic requirement for the oil pump is that it can still work normally and have good sealing under the action of high-temperature heat transfer oil. In addition, according to the design requirements, the heat value that needs to be carried away by the heat transfer oil during mold cooling should be calculated based on the thermal balance of the mold, and the required heat transfer oil flow rate should be calculated. Based on the size of the heat transfer oil flow rate, the corresponding high-temperature oil pump should be selected.
The design of the magnesium aluminum alloy die-casting mold temperature machine mainly considers meeting the requirements for mold preheating. The exterior of the heater must be wrapped with a sufficiently thick layer of insulation material to reduce heat loss. Without considering the heat dissipation of the circulation path of the temperature controller itself, the heating power can be calculated based on the size of the mold, the heating time, and the heat dissipation of the mold itself. According to the calculation results, select a rod-shaped heater with the corresponding power. During processing, the heating rod can be integrated with multiple thin oil pipes through cast aluminum to ensure uniform and rapid heating, while avoiding carbonization of the heat transfer oil caused by overheating.
The design of the cooling system for magnesium aluminum alloy die-casting molds is mainly to meet the requirements of mold heat dissipation. Perform thermal balance calculation on the mold to obtain the heat that needs to be carried away by the heat transfer oil. This heat is then exchanged through a cooler and carried away by the cooling water. A complete set of tube heat exchangers is designed for the cooler, with cooling water flowing through the inner tube and heat transfer oil flowing through the interlayer between the inner tube and the outer shell. The processing and manufacturing of sleeve heat exchangers are simple, but the heat transfer surface of sleeve heat exchangers is small and the heat transfer is not significant. Therefore, in the use of magnesium aluminum alloy die-casting mold temperature machines, two or more sleeve heat exchangers can be connected in series as needed to form multi tube and multi shell heat exchangers, meeting the design and usage requirements.
In addition, the magnesium aluminum alloy die-casting mold temperature machine must ensure strict sealing at all places under the action of high-temperature heat transfer oil, otherwise, large smoke will be generated on the surface of the parts, which will have adverse effects on the working environment of the workshop.

4、 Magnesium aluminum alloyDie casting mold temperature machineControl system development
The control system of the magnesium aluminum alloy die-casting mold temperature machine consists of PLC, human-machine interface display, sensors, and corresponding execution components.
The system uses Siemens PLC as the core controller to complete various types of switch input signal detection, sensor signal detection, and control signal output. During the production process, the human-machine interface display communicates with the PLC to send the data collected by the PLC to the human-machine interface display, displaying the system's working status in real time, and sending the user set parameters (such as temperature) to the PLC to achieve user parameter settings.
The magnesium aluminum alloy die-casting mold temperature machine adopts a resistance heater, and during heating, a solid-state relay zero crossing triggering power regulation control method is used; The control method of cooling the system by connecting the solenoid valve and cooling water is adopted. In terms of control algorithm, fuzzy control is used for temperature control. Due to the varying sizes and variations of die-casting molds and parts in production, as well as the need to replace molds from time to time, the PID algorithm commonly used in temperature control has significant limitations. Different control parameters must be adjusted according to different molds, which is inconvenient. Therefore, in algorithm design, fuzzy control is adopted for temperature control of the mold. In the early stage of the mold heating process, full power output is used to rapidly heat up the mold. When the mold temperature reaches about 80% of the set temperature, the system adopts fuzzy control for the output variable (i.e. output power) to avoid significant overshoot; When conducting cooling control in continuous die-casting, the system also uses fuzzy control algorithm to control the on/off of the cooling water control solenoid valve, maintaining the temperature of the mold at a predetermined temperature. Due to the fact that the power regulation of solid-state relays and the on-off control of cooling water solenoid valves are both done in a switch mode, the system converts the results of fuzzy operations into a square wave with a fixed period and adjustable duty cycle, forming the required control signal. This control method has good adaptability to molds of different sizes, maintaining high stability and accuracy at the set mold temperature.