Variable-temperature injection mould circulating system

A circulatory system and injection mold technology, applied in the field of circulatory system for controlling the temperature of plastic molds, can solve the problems of poor product accuracy, high polymer melt viscosity, and unavoidable internal stress.

Inactive Publication Date: 2010-11-24
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AI-Extracted Technical Summary

Problems solved by technology

[0002] Plastic injection molding products play a very important role in various industries of the national economy such as agriculture, national defense construction, transportation, instrumentation, etc., but according to the traditional injection molding process, there are inherent deficiencies, and the formed products inevitably exist. Many defects, the common ones are poor product precision, lack of material (cavity is not full), shrinkage, surface depression, obvious weld lines, large internal stress of the product, and serious problems such as cracking during demoulding or use.
Most of the above-mentioned defects are caused by the injection molding process itself. For example, most p...
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The invention relates to a variable-temperature injection mould circulating system which comprises a hot oil system, a cold oil system and an oil return delay system, high-temperature high-thermal conductivity oil is used as a heat transfer medium, and the heating and the cooling of heat using equipment are balanced through a hot oil pump and a cold oil pump with the same flow speed. The oil pumps continuously work, and the flowing process of the oil is changed through a pressure-regulating valve. When a mould is heated, the hot oil is introduced and returns to a hot oil tank; when the mould is cooled, the cold oil is introduced and returns to a cold oil tank to ensure that the hot oil and the cold oil can not be mutually mixed. An oil return delay switching technology is adopted to finish the complete disconnection of cold and hot oil systems, and the energy utilization ratio is improved.

Technology Topic

Thermal conductivityFuel tank +2


  • Variable-temperature injection mould circulating system
  • Variable-temperature injection mould circulating system


  • Experimental program(1)

Example Embodiment

[0012] by figure 1 It is known that the present invention consists of heating equipment 1, hot oil pump 2, hot oil storage tank 3, cold oil pump 4, cold oil storage tank 5, electric heater 6, flow regulating valve 8, solenoid valve 9, manual control valve 10 and pressure The regulating valve 11 is composed, and the various components are connected by selecting the high temperature and high pressure oil pipe 7 of corresponding specifications. The initial state of the system is that the solenoid valves 9-1 and 9-2 are closed, the hot oil pump 2 and the cold oil pump 4 are started, and the electric heater 6 and the cooling water of the cooling water pipe are in normal working conditions. 1, 9-2 is in the closed state, when the oil pressure of the oil pump reaches 0.2MPa set pressure of the pressure regulating valve 11, the hot oil and cold oil will automatically flow back to the hot oil storage tank 3 and the cold oil storage tank through the pressure regulating valve 11 5. Keep hot oil and cold oil in a turbulent state to speed up heat transfer.
[0013] When the oil temperature of the hot oil storage tank 3 reaches the set temperature of 200°C, the solenoid valve 9-1 and the manual control valve 10-1 are opened, and the hot oil passes through the heating device 1 to heat the mold, and when the heating device 1 reaches the setting ( When the temperature is above the melting temperature of the plastic, the solenoid valve 9-1 is closed, and the manual control valve 10-1 is closed, and the time T1 for heating the mold to the set temperature is recorded. Open the solenoid valve 9-2, manually control the valve 10-2, and start to pass cold oil to cool the mold. When the heating device 1 reaches the set temperature (plastic ejection temperature), the solenoid valve 9-2 is closed and the manual control valve 10 -2 Close, and record the time T2 used to cool the mold to the set temperature.
[0014] When the heating and cooling time of the actual mold is determined, the automatic control program for cooling and heating of the mold is set. Set the open time of solenoid valve 9-1 to T1, set the open time of solenoid valve 9-2 to T2, close the manual control valves 10-1, 10-2, and calculate the time T3 when the oil in the heating device 1 is exhausted , As the basis for the delay time. Start the program, the solenoid valve 9-1 opens, and the opening time is T1. At this time, the solenoid valve 9-4 closes T3 after a delay, so that the cold oil of the system flows back to the cold oil tank. When the solenoid valve 9-4 is closed after the time T3 expires, the solenoid valve 9-3 opens to ensure that the hot oil returns to the tank. When the heating oil time T1 expires, the solenoid valve 9-2 is braked and opened, and the opening time is T2. Similarly, the solenoid valve 9-3 is delayed to close T3 to ensure that the hot oil is fully returned to the oil tank, and so on. Make the mold temperature have different temperature changes in different injection molding cycles to meet the requirements of the injection molding process and produce high-quality products.
[0015] Said use of high temperature and high thermal conductivity oil as the heat transfer medium, the heating fluid oil flows at high speed in the mold, the Reynolds index (Re) reaches 60,000, and the heat coefficient is increased. The hot oil pump 2 and cold oil pump 4 of the same flow rate make it The heating and cooling of the heating device 1 are balanced. The hot oil is continuously heated by the electric heater 6, and the cold oil is continuously cooled by the cooling water circulation system in the cold oil storage tank 5. Due to the short injection cycle of the mold, in order to improve the service life of the oil pump, the oil pump is used to work continuously, and the pressure regulating valve 11-1, 11-2 is used to change the oil flow path. The high temperature oil is controlled at 190℃, the low temperature oil is 30℃, and the target temperature of the mold surface is 150℃ for high temperature and 45℃ for low temperature. In order to improve the heating efficiency and save energy, when the mold is heated, the hot oil is passed through and the hot oil returns to the oil storage tank 3; when the mold is cooled, the cold oil is passed through, and the cold oil returns to the cold oil storage tank 5 to ensure hot and cold oil Will not mix with each other. Although the cold and hot oil will not mix with each other in the normal cycle, a small amount of hot oil in the mold oil passage will still enter the cold oil system within a short time when the cold and hot oil are switched, and the cold oil in the flow path will be switched Will also enter the hot oil system. In order to minimize the mixing of hot and cold oil during switching, the oil return delay switching technology is adopted. When the incoming hot oil is switched to cold oil, the oil return line will not switch to the cold oil line temporarily, and the hot oil in the mold oil channel will be cooled. After the oil is almost replaced, the oil return is switched to the cold oil circuit, and finally the cold and hot oil system is completely disconnected.


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