Mold temperature control system of the hottest hig

2022-08-18
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Mold temperature control system of high gloss traceless injection molding process

the key of high gloss injection molding is the mold temperature control system. Because the biggest difference between high gloss injection molding and general injection molding is the control of mold temperature, and the requirements for injection molding machine are not high. The high gloss injection mold temperature control system is generally also known as the high gloss mold temperature machine, which coordinates with the general injection molding machine in the process of filling, pressure maintaining, cooling, opening and closing the mold

the heating method of the mold surface is the key technology of the temperature control system. The high gloss mold surface mainly obtains heat through the following ways. The first is the heating method based on heat conduction, such as transferring heat to the surface of the mold through oil, water, steam, electric heating elements, etc. in the internal pipes of the mold; The second is the heating method based on thermal radiation, such as solar energy, laser beam, electron beam, infrared light, flame, gas and other direct radiation to the mold surface; Third, the mold surface generates heat by heating itself through its own thermal field, such as resistance and electromagnetic induction heating. At present, practical heating systems include: oil temperature machine for high-temperature oil heat transfer, high-pressure water temperature machine for high-temperature and high-pressure water heat transfer, steam mold temperature machine for steam heat transfer, electric heat mold temperature machine for electric heat pipe heat transfer, electromagnetic induction heating system and infrared radiation heating system

(L) oil temperature machine with high temperature oil heat transfer

uniform heating or cooling pipes are designed inside the mold, which can achieve the effect of mold preheating through the oil heating system, and has the effect of cooling in the injection process. The maximum temperature can reach 350 ℃. Due to the low thermal conductivity and efficiency of oil, and the oil and gas produced affect the quality of highlight molding, but the effect is not ideal. However, at present, the oil temperature machine in enterprises is relatively common and has rich experience in use

(2) high pressure water temperature machine with high temperature and high pressure water heat transfer

balanced pipes are designed inside the mold, and water of different temperatures is used in different stages. High temperature superheated water is used for heating, and low temperature cooling water is used for cooling to realize the heating or cooling of the mold surface. If water is pressurized, the temperature rise can also reach 140 ~ 180 ℃, and the temperature rises quickly. Manufacturers of high-temperature and high-pressure water temperature control system include: for example, the GWS system of Aode, because the hot water can be recycled and the operation cost is low, it is widely used in the domestic market at present, and it is also the best choice to replace steam

(3) the steam mold temperature machine for steam heat transfer

is similar to the action principle of the high-pressure water temperature machine. A balanced pipe is designed inside the mold, which is connected with steam during heating and switched to low-temperature water during cooling, so as to realize the heating or cooling of the mold surface (compressed air is generally required to blow the pipe dry before steam heating). The high temperature and high pressure steam heating system can make the maximum temperature of the die surface reach 160 ℃. Because the heat capacity of steam is smaller than that of water, the relative heating time is longer. It needs about 300 ℃ steam to reach 150 ℃ mold surface temperature. However, due to the non recyclability of steam in the production process, it is necessary to install boiler equipment and lay pipelines, resulting in high operating costs

(4) electric heating mold for heat transfer of electric heating tube inclined plane impact tester is widely used. The temperature machine

adopts resistance heating elements (electric heating plate, electric heating frame, electric heating ring, etc.) as the heat source, of which electric heating tube is widely used. It takes metal tube as the shell (including stainless steel, copper tube), and uniformly distributes spiral electric heating wires (nickel chromium, iron chromium alloy) along the central axis of the tube, The gap is filled and compacted with magnesia with good insulation and thermal conductivity, and both ends of the pipe orifice are sealed with silica gel. Electric heating elements can heat air, solids and various liquids. At present, the heating system of electric heater directly installed in the mold has a high cost and needs to pay the patent fee for mold design. The heating speed of the electric heating tube is fast, and the control temperature range can reach 350 ℃. After using this system, the mold temperature can be heated to 300 ℃ in 15s, and then cooled to 20 ℃ in 15s. But it is only suitable for smaller products. Due to the high direct heating temperature of the heating wire, the relative die life will be shortened

(5) high frequency electromagnetic induction heating system

increases the temperature of the workpiece according to the principle of electromagnetic induction. Due to the skin effect, the eddy current generated on the surface of the workpiece is the strongest, while it is very weak inside, and close to zero to the core. Therefore, this method can only heat the workpiece surface to the skin depth, so the heating volume is small, the heating speed is fast, and the heating speed is more than 14 ℃/s. For example, the heating speed of the system developed by Taiwan Zhongyuan University has reached more than 20 ℃/s. After the surface heating is completed, coupled with the rapid low-temperature cooling equipment, the effect of rapid heating and cooling of the mold surface can be achieved, and the variable mold temperature control can be realized

(6) researchers of infrared radiation heating system are developing the way of using infrared radiation to heat the cavity directly. The heat transfer form of infrared ray is radiation heat transfer, which transmits energy by electromagnetic waves. It does not need heat transfer medium and has certain penetration ability. Compared with other methods, it has the advantages of energy saving, safety, simple equipment and easy promotion. However, due to the absorption capacity of bright metal strong J hongxibu line, the advantage of the small panel control system is that the control of the experimental machine is weak and the heating speed is slow

(7) gas receipt system

high temperature gas is used as the medium to quickly change the mold temperature. Before the filling stage, the gas is injected into the mold cavity quickly and accurately, which can instantly increase the mold surface temperature to about 200 ℃, and the high temperature area can be controlled near the mold surface, which will not cause the matching degree problem of size expansion of other parts of the mold due to the temperature Jinghua. This technology does not need to make much modification to the existing mold, and the mold manufacturing cost is low, but the sealing requirements are high

at present, there are still some problems to be solved in the temperature control system. First, there are few practical heating methods, which are more successful in heating steam and high-temperature water. Second, high gloss injection molding adopts a separate mold temperature control system, which needs to be used in conjunction with the injection molding forum. Third, the equipment and operation costs are high. How to make the variable mold temperature control technology carry out economic scale production without affecting the molding cycle is a problem that everyone is competing for development and breakthrough. In the future, it is necessary to further research and develop practical low-cost rapid heating methods and integrated high gloss injection molding machines

high gloss injection molding is the most common name for injection molding enterprises at present. From the perspective of the gloss of injection products, due to the increase of the interface temperature between the melt flow front and the mold surface contact point, it can make it easy to replicate the fine shape of the mold part. For example, combined with the mold with high gloss surface and special engineering plastics, it can produce high gloss injection products to achieve the final product of one-step injection molding success, which is called high gloss injection molding, Its full name should be variable mold temperature injection molding of high gloss products. In addition, there are many other names, such as: this process adopts rapid heating and cooling, which is called rapid heat cycle injection molding (RHCM); From the perspective of mold temperature change, it is called variable mold temperature, dynamic mold temperature, alternating cold and hot mold temperature control technology; From the perspective of eliminating post-treatment processes such as spraying, it is called spray free injection molding; From the perspective of eliminating surface defects, it is called seamless injection molding. In terms of heating methods, it is also known as the use of tensile testing machine for experiments, including steam type, electric heating type, hot water type, high oil temperature type, induction heating type mold temperature control technology, etc. From the perspective of mold temperature control machine, it is also called steam mold temperature machine, superheated water mold temperature machine, electric mold temperature machine, water temperature machine, oil temperature machine, electromagnetic induction mold temperature machine, etc. (end)

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