Analysis of main problems and solutions of electric heating plate:
1. The heating temperature of the electric heating plate cannot meet the requirements
a. With the continuous improvement of the current process, the equipment cannot meet the product molding requirements;
b. The heating uniformity of the electric heating plate is insufficient, and the heating can not be well zoned, resulting in low product yield;
c. The electric heating tube is heated with large thermal inertia and unstable heating rate.
2. High failure rate of electric heating tube direct heating
a. Most electric heating plates are controlled by multiple solid state relays, and multiple heating tubes control heating, which increases the probability of failure;
b. The heating circuit is easy to heat and burn, high maintenance cost, and there are safety risks;
c. Because the electric heating tube is directly inserted into the heating plate, the heating tube is exposed to the air for long-term heating and cooling. The electric furnace wire in the heating tube is easy to oxidize, has a short service life, high maintenance cost, and has potential safety hazards;
3. Heating by oil heat conduction method
a. In response to the above problems, Chengdu Zhengxi Hydraulic Equipment Manufacturing Co., Ltd. has a very mature solution, using heat transfer oil thermal cycle mold temperature machine heating;
b. The mold temperature machine can realize automatic temperature control of the heated objects. Electric heating source of heating equipment, heat transfer oil as heat carrier, using high temperature circulating oil pump to force circulation to transfer heat energy to the heating area; then return to the DC heating equipment to continue heating again, repeating this cycle to achieve a continuous increase in heat, so that the object to be heated The temperature rises and the process of reaching a heating constant temperature requires the use of medium circulation indirect heating, uniform heating, indirect temperature control, rapid temperature rise and fall, simple maintenance, and low thermal inertia;
4. Zone control to improve temperature uniformity
a. In the case of high-precision temperature control of the mold temperature machine, in view of the problem of low temperature uniformity, Chengdu Zhengxi Hydraulic Equipment Manufacturing Co., Ltd. adopts a hot plate zone single-action control scheme; for example, the size of the hot plate is 4.5m X 1.6m , A single hot plate is divided into three zones of 1.5 meters X 1.6 meters for independent temperature control and heat compensation. The upper and lower hot plates adopt 6 oil circuits and 6 zones for temperature control, and the temperature uniformity is more guaranteed;
b. The mold temperature machine is equipped with two closed-loop controls, among which the oil temperature and the oil circuit system are used as a closed-loop control to ensure that the oil temperature can be within the controllable range ±1℃; the set temperature and the mold or hot plate temperature are formed again Closed-loop control, real-time temperature control of the mold, more secure.
The difference between electric heating rod and oil temperature machine
1. The advantages of electric heating rods: direct heating, no dielectric loss, fast heating speed, relatively low cost, and easy to insert directly into the hot plate;
2. Disadvantages of electric heating rods: uneven heating, high maintenance cost (requiring frequent replacement of heating rods), complex disassembly, large thermal inertia, and large heating plate heating tube lines are unsafe;
3. Advantages of oil temperature machine: use medium circulation indirect heating, high heating uniformity, indirect temperature control, rapid temperature rise and fall, simple maintenance, small thermal inertia, strong controllability, direct heating and precise control of cooling;
4. Disadvantages of the oil temperature machine: the maintenance of the equipment will cause medium loss, and the first investment cost will be higher;
Oil leakage prevention measures of oil temperature machine
1. The system pipeline adopts GB 3087 special pipes for medium and low pressure boilers, and the 20# pipeline is integrally formed to ensure that the system is reliable and does not leak oil;
2. The fuel tank adopts a liquid level detection device. Once the system leaks, the liquid level of the fuel tank decreases and the equipment stops and alarms;
3. The pipeline adopts a pressure detection device. Once the system leaks oil, the pump cycle pressure decreases and the heating pressure cannot be reached, and the system prohibits heating;
4. The heating pipe anti-dry burning detection device, once the system has oil leakage, the heating pipe’s dry burning temperature will increase significantly, and the system is prohibited from running.
5. The equipment is equipped with alarms for oil leakage, failure, damage, etc. Once a failure occurs, the system judges to automatically terminate or upgrade the operation and display the error condition.
Post time: Dec-08-2020
