Heating mode of circuit board press
Circuit board press there are mainly three heating methods: steam, superheated water and hot oil.
A. The steam is directly sent to the laminator by the steam boiler for steam heating. The steam temperature is proportional to the steam pressure. As long as the steam pressure is well controlled, the purpose of temperature control can be achieved. With steam as the heat source, the temperature difference of the laminator fluctuates greatly. The hot pressing plate can be cooled directly with cold water. The steam heating equipment is simple in composition and less in investment, so it is still used by many CCL plants.
B. The superheated water is heated by the steam boiler to the superheated water storage tank. When the temperature reaches the set value, the steam boiler only supplements the heat loss of the superheated water storage tank. Therefore, this design is more energy-saving. The superheated water storage tank and the laminating machine have a circuit. When the laminating machine needs heating, the pump will pump the superheated water in the storage tank into the hot pressing plate of the laminating machine. The hot pressing plate itself has a thermal cycle. When the heat loss fails to meet the set requirements, the storage tank will add some fresh superheated water to ensure that the temperature of the hot pressing plate remains within the process requirements. Therefore, the temperature difference can be within ± 1 ℃. During cooling, the superheated water of the laminator circuit is cooled gradually by a heat exchanger. A separate cooling water circuit can also be used to cool the hot pressing plate. The investment of using superheated water is relatively large, and there is no application report in domestic copper clad plate plants, while more are used in foreign copper clad plate plants.
C. The heating form of hot oil is similar to that of superheated water, which is also realized by a hot oil storage tank. The hot oil boiler heats the hot oil storage tank, and the hot oil storage tank heats the laminator. The hot pressing plate itself has a thermal cycle. When the temperature of the hot pressing plate is lower than the set value, the hot storage tank will add some fresh hot oil to maintain the temperature of the hot pressing plate within the set range. Generally, the temperature difference can be controlled within ± 1 ℃ to meet the production requirements of the copper clad plate. Cooling is to circulate the hot oil of the hot pressing plate through one or several heat exchangers to gradually cool the hot oil to realize the purpose of gradually cooling the hot pressing plate. As the cooling process has a certain impact on the warpage and dimensional stability of the product, the cooling of the laminating machine has a variety of forms of design. It should not only meet the requirements of slow cooling before fast cooling as required by the process to ensure product quality, but also not make the production cycle too long, and at the same time, it should be conducive to energy conservation. Heating with superheated water, like steam, the temperature of superheated water is proportional to the pressure, so the system pressure is high and the risk is great. The heating of hot oil is normal pressure, and the system pressure is the pressure of the hot oil pump, so there is no danger. The cost of the hot oil system is also high. Because of its high temperature control accuracy, it can also be realized if higher heating temperature is required in production, because the thermal decomposition temperature of synthetic hot oil is above 310 ℃, while steam and superheated water cannot, and many domestic copper clad laminate plants have adopted oil heating systems.
When using superheated water and hot oil as the heat source of the laminating machine, carefully calculate the heat energy demand of the laminating machine to determine the heating capacity of the hot oil boiler and the volume of the hot oil storage tank. During design, space for plant development shall be reserved.
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