1, the heat balance control of injection mold injection molding machine and mold thermal conductivity is the key to producing injection molded parts. Internal mold, made of plastic (such as thermoplastics) caused by thermal radiation heat transfer to the material and mold steel, heat conduction through the fluid circulating handed. In addition, the heat transfer by thermal radiation into the atmosphere and is mold. Thermal conductivity of the fluid is absorbed by the mold temperature to the heat away. Mold thermal equilibrium can be described as: P = Pm-Ps. Where P is the mold temperature away the heat; Pm plastic into heat; Ps emitted to the atmosphere to heat the mold.
2, the purpose of controlling mold temperature and mold temperature on the impact of injection molded parts injection molding process, the main purpose of mold temperature control of the mold is heated to one temperature, the second is to maintain a constant temperature in the mold temperature. The success of these two points do, you can optimize the cycle time, thereby ensuring the stability of high-quality injection molded parts. Mold temperature will affect the surface quality, liquidity, shrinkage, deformation and molding cycle aspects. Mold temperature too high or inadequate for the different materials will have different effects. Of thermoplastics, the mold temperature is usually a little higher will improve the surface quality and liquidity, but will extend the cooling time and injection molding cycle. Lower mold temperature will reduce the shrinkage in the mold, but will increase after the injection molding mold shrinkage. While thermosets, the higher mold temperature will usually reduce cycle time and cooling time from part time decision. In addition, plastic processing, the higher mold temperature will reduce the plasticizing time, reduce cycle times.
3, effective control of the preparation conditions of mold temperature control system consists of the mold temperature, mold temperature, heat transfer fluid of three parts. To ensure that heat can be added to the mold or removed parts of the system must meet the following conditions: first, in the mold inside the cooling channel surface area must be large enough in diameter to match the flow capacity of the pump (pump pressure). Cavity in the temperature distribution of parts deformation and internal pressure have a great impact. Reasonable to set the internal pressure of the cooling channel can be reduced, thus improving the quality of injection molded parts. It can also shorten the cycle time, reduce product cost. Followed by the mold temperature must be able to heat the fluid temperature constant at 1 -3range, depending on the quality of injection molded parts required to be. The third is the thermal conductivity of the fluid must have good thermal conductivity, most importantly, it must be able to import or export in a short time a lot of heat. From the thermodynamic point of view, the water was significantly better than oil.
4, mold temperature machine works by the water tank, heating and cooling systems, power transmission systems, level control system and temperature sensors, sprue and other device components. Typically, power transmission systems in the thermal fluid from the pump with built-in heater and cooler tank to reach the mold, and then die back from the water tank; temperature sensors measure the fluid temperature and heat transfer to the control part of the data controller; controller regulates the temperature of hot fluid, and thus indirectly regulate the temperature of the mold. If the mold temperature in the production, the mold temperature exceeds the set value the controller, the controller will open the solenoid valve connected into the water, heat until the liquid temperature, mold temperature back to set that value. If the mold temperature is below the set value, the controller will turn on the heater.
5, the type of mold temperature is based on the use of heat transfer fluid (water or thermal oil) to the division. With the transport of water-type mold temperature is usually the maximum outlet temperature of 95 . With an oil-type mold temperature machine operating temperature 150 for the occasion. Under normal circumstances, with open water tank for heating the mold temperature machine with a water temperature or oil temperature machine, maximum outlet temperature of 90 to 150 , mold temperature of this unit's main feature is designed to be simple and affordable. In this machine also derived on the basis of a machine using hot water temperature, which allows the outlet temperature of 160 or higher, due to the temperature higher than 90 , the water thermal conductivity with temperature than the oil much better, so this machine has a prominent high-temperature working ability. In addition to time, there is a forced flow of the mold temperature machine, for security reasons, the mold temperature design temperature above 150 , the use of thermal oil. To prevent mold temperature in the oil heater overheating, the aircraft uses a forced flow pumping system, and the heater tube by a number of stack components, the pipe has a heating element with fins for the diversion.
6, control the temperature inside the mold uneven points, and also injection cycle time related. After the injection mold cavity temperature rose to the highest, then hit the hot melt cold wall cavity, when the temperature after the removal of parts to a minimum. Mold temperature effect is to keep the temperature constant and 2max in 2min between, that is to prevent the temperature difference or gaps in the production process fluctuations. The following types of control methods for control of mold temperature: the temperature control fluid is the most commonly used method, and the control precision can meet most requirements. Using this control method, the temperature displayed on the controller and the mold temperature is not uniform; considerable fluctuations in temperature of the mold, the mold thermal factors which affect not directly measure and compensate for these factors include changes in the injection cycle, injection speed, melt temperature and room temperature. The second is the direct control of mold temperature. This method is internally mounted temperature sensor in the mold, which mold temperature control precision is relatively high in the case will be used. Mold temperature control of the main features include: the temperature controller set temperature with the same mold; factors affecting the thermal mold can be directly measured and compensated. Typically, the mold temperature stability better than that by controlling the fluid temperature. In addition, the mold temperature control in the production process control of reproducibility. The third is joint control. Joint control is the combination of methods, it can also control the flow and mold temperature. In the joint control of the temperature sensor position in the mold is extremely important, and temperature sensor, we must consider the shape, structure and location of the cooling channel. In addition, the temperature sensor should be placed on the quality of injection molded parts where played a decisive role. Connect one or more of the injection molding machine mold temperature controller, there are many ways. From operational, reliability and performance to consider the best use of digital interfaces such as RS 485. In the injection molding machine control unit and the transmission of information between the software can be. Mold temperature can be automatically controlled.
7, mold temperature machine configuration and use of mold temperature machine's configuration should be based on processing of the material, the weight of the mold, requiring warm-up time and productivity kg / h to a comprehensive determination. When using heat-conducting oil, the operator must comply with safety requirements such as: Do not close the mold temperature on the stove where the heat source; joint use of taper of the leak-proof and has a temperature pressure hose or hard tube; regular inspection temperature control loop mold temperature, and mold without leaking joints, function properly; regular replacement of heat-conducting oil; should use artificial synthetic, thermal stability, coking propensity small. In the use of mold temperature machine, select the appropriate heat transfer fluid is critical. Water as heat transfer fluid economic, clean, easy to use, once the temperature control loop, such as hose couplings leak out of the water flow can be directly discharged into the sewer. However, water as heat transfer fluid water also has disadvantages: the low boiling point of water; according to the composition of the water may be corrosive and scaling, and increasing the pressure loss caused by mold and heat exchange efficiency between the fluids down, and so on. Using water as a heat transfer fluid should be considered when the following preventive measures: pre-treatment with anti-corrosive temperature control circuit; inlet filter before use; cleaning agents regularly with rust and mold temperature machine. No water with heat-conducting oil shortcomings. High boiling point oil, which can be used for temperatures higher than 300 or higher, but heat transfer oil heat transfer coefficient of water is only 1 / 3, so there was no oil in the injection molding machine with a wide range of temperature machine.