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Mold temperature machine injection mold Applications

 

1, the heat balance control of injection mold injection molding machine and mold thermal conductivity is the key to production of injection molded parts. The die from the plastic (eg thermoplastics) caused by thermal radiation heat transfer to the material and die steel, heat conduction through the fluid circulating handed. In addition, heat through thermal radiation has been delivered to the atmosphere and the mold. Thermal conductivity of the heat absorbed by fluid from the mold temperature machine to take away. Die thermal equilibrium can be described as: P = Pm-Ps. Where P is the heat taken away by mold temperature machine; Pm for the plastics into heat; Ps for mold heat emitted to the atmosphere.

2, control the purpose of mold temperature and mold temperature on the impact of injection molded parts injection molding process, the control of the main purpose of mold temperature will die first, heated to working temperature, the second is to maintain the mold temperature constant at the operating temperature. The success of these two points to do so, the cycle time can be optimized, thereby ensuring a stable, high-quality injection molded parts. Mold temperature will affect the surface quality, liquidity, contraction rate, injection molding cycle as well as deformation of several areas. Mold temperature is too high or less pairs of different materials will have different effects. Pairs 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 period. Lower mold temperature will reduce the shrinkage in the mold, but will increase the injection molded parts after ejection shrinkage. While thermosetting plastics, the higher mold temperature will usually reduce the cycle time, and the cooling time from part time decision. In addition, plastics processing, the higher mold temperature will also reduce plasticization time, reduce cycle times.

3, effective control of the preparation conditions of mold temperature control system consists of mold temperature, mold temperature machine, heat transfer fluid of three parts. In order to ensure that the heat can be added to the mold or the removal of parts of the system must meet the following conditions: first, the die inside the cooling channel surface area must be large enough in diameter to match the pump flow channel capacity (pump pressure). Cavity in the temperature distribution on the part deformation and internal pressures have greatly affected. 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 costs. Followed by mold temperature machine must be able to heat the fluid temperature constant at 1 ℃ -3 ℃ within the context of a specific quality requirements according to injection molded parts to be translated. The third is the thermal conductivity of fluid must have good thermal conductivity, the most important of all, it must be able to import or export in a short time a lot of heat. From the thermodynamics point of view, water, significantly better than oil.

4, the working principle of mold temperature machine from the water tanks, heating and cooling systems, power transmission systems, liquid level control system as well as temperature sensors, injection devices such as the composition of the entrance. Typically, power transmission systems in the thermal fluid from the pump is equipped with built-in heater and cooler tank to reach die, then die back from the water tank; temperature sensors measure the temperature of hot fluid flow and the data sent to the control part the controller; controller regulate the temperature of hot fluid, thereby indirectly regulate the temperature of mold. If the mold temperature machine in production, the mold temperature exceeds the set value the controller, the controller will open the solenoid valve connected into the pipe until the temperature of liquid heat that the temperature back to set the value of the mold. If the mold temperature is lower than the set value, the controller will open the heater.

5, mold temperature machine types is based on the use of thermal conductivity of fluid (water or HTF) to division. Used to transport water-type mold temperature machine is normally the largest outlet temperature of 95 ℃. With the tanker-type mold temperature machine for operating temperature ≥ 150 ℃ occasions. Under normal circumstances, with an open water tank heated mold temperature machine is suitable for machine or oil temperature with the temperature of machines, maximum outlet temperature of 90 ℃ to 150 ℃, the mold temperature machine main feature is designed to be simple, affordable price. In such a machine based on the use of another derivative of a high temperature machine, which allows the exit temperature of 160 ℃ or higher, since the temperature is higher than 90 ℃ when the thermal conductivity of water temperature than other oils much better, so this machine has a prominent high-temperature working ability. In addition to time, there is a forced flow of mold temperature machine, for security reasons, this mold temperature machine design operating temperature of 150 ℃ and above, using heat conducting oil. In order to prevent mold temperature machine oil inside the heater overheating, the aircraft using the forced-flow pumping system, and the heater tube by a number of stack composed of a tube with fins of the heating element for the diversion.

6, control the temperature of various points inside the die uneven, but also and injection point of the cycle time. After the injection mold cavity temperature rose to the highest, when hot-melt run into the cold cavity wall, when the parts removed, the temperature dropped to a minimum. Mold temperature machine's role is to keep the temperature constant at θ2min and θ2max between the means to prevent the temperature difference △ θw gap in the production process or fluctuate. The following are several control methods applied to control the mold temperature: controlling fluid temperature is the most common method, and the control precision can meet most requirements. Using this control method, displayed in the controller's temperature and mold temperature are not the same; mold temperature fluctuations quite large, because the thermal factors that affect the mold did not directly measure and compensate for these factors include the injection cycle changes, injection speed, melt temperature and at room temperature. The second is the direct control of mold temperature. The method is installed inside the die temperature sensor, which in the mold temperature control of high accuracy requirements under which it will use. Mold temperature control key features include: controller set temperature and mold temperature are consistent; thermal factors can affect the die directly measured and compensation. Under normal circumstances, mold temperature stability better than that by controlling the fluid temperature. In addition, the mold temperature control in the production process control of the good reproducibility. The third is joint control. Joint control is the combination of methods that can simultaneously control the flow and mold temperature. In the joint control, temperature sensors in the mold the position is extremely important, and the 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 play a decisive role. Connected to one or more machines to the injection molding machine mold temperature controller, there are many ways. From the operational, reliability, and anti-jamming consider the best use of digital interfaces such as RS 485. In the control unit and between the injection molding machine to transmit information through the software. Mold temperature machine can also be automatic.

7, mold temperature machine configuration and use of mold temperature machine's configuration should be based on processing of materials, mold weight, required 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 die temperature near the heat source machine on the stove place; joint use of taper of the leak-proof and has a temperature pressure hose or hard tube; regular checks temperature control loop mold temperature machine, whether the leaked joints and die, function is normal; periodic replacement of heat-conducting oil; should opt for artificial synthetic, thermal stability, coking tendency of small. In the use of mold temperature machine, select the appropriate thermal fluid is critical. Thermal conductivity of liquid water for 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, for thermal conductivity of liquid water, water also has disadvantages: a low boiling point of water; according to the composition of the water may be corrosion and scaling, causing pressure loss increases and the mold and fluid heat exchange between the reduced efficiency and so on. The use of water as a thermal conductivity of fluids, they should consider the following precautionary measures: pre-treatment with anti-corrosive temperature control circuit; intake filters used before; regularly with rust water temperature machines and mold cleaning agents. When using heat-conducting oil no water deficiencies. A high boiling point oil, which can be used for temperature higher than 300 ℃ or higher, but the heat transfer coefficient of heat conducting oil is only water, 1 / 3, so the oil temperature in the injection molding machine there is no machine wide range of temperature.
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