Maintenance example of electric blast Drying Oven

Electric Forced Air Drying Oven, also known as oven (hereinafter referred to as oven), is an experimental instrument used in the laboratory to dry samples, and can also provide various temperature environments required for experiments. It is used in biological material preparation, chemical industry, medicine, casting, It is widely used in food, automobile and other industries.

1 Oven Composition

The oven is mainly composed of functional modules such as electric heater, blower, temperature controller, box shell and working room.

The heating of the oven is done by an electric heater. Because the heating wire in the air is easy to oxidize due to high temperature and long-term heating, it affects the service life. Therefore, the heater usually uses an electric heating tube, that is, the heating wire is placed inside the heating tube, which can reduce the oxidation rate and increase the life. At the same time, the heat is transferred to the steel pipe to increase the heat conduction area.

The blower of the oven generally uses a high-temperature-resistant motor. The airflow generated by the wind wheel passes through the electric heating tube to send the hot air out, and then passes through the air duct to the inside of the oven. Indoor temperature uniformity.

The temperature controller of the oven is used to control and display the temperature. When the temperature in the box is lower than the set temperature, the thermostat controls the heater to heat continuously or intermittently, so that the temperature in the box can be controlled.

2 Examples of Oven Maintenance

2.1 Maintenance of DHG-9075 oven

(1) Fault phenomenon: DHG-9075 type oven can be heated, but the fan cannot work.

(2) Fault analysis: From the analysis of the functional module composition of the oven above, it should be that the blower and its related circuits have failed.

Use a multimeter to measure the resistance of the running winding and starting winding of the fan coil, which shows that the coil is not blown. Because the fan is a single-phase motor driven by 220 V, the single-phase current cannot generate a rotating magnetic field, so certain methods must be adopted to generate a rotating magnetic field, and phase separation with capacitors is a common method. Therefore, it is suspected that the capacitor is damaged, causing the fan to fail to start. The capacitor model is CBB61, 0.8 μf/450V, measured with the 10 k resistance range of the multimeter, the pointer basically does not move, indicating that the capacitor cannot be charged and discharged normally.

(3) Problem solving: replace the capacitor, because the capacitor with the same specification cannot be purchased, replace it with a 1 μf/450 V capacitor, and the fan runs normally after starting up.

2.2 Maintenance of ZK40 oven

(1) Fault phenomenon: ZK40 type oven cannot be heated, and the temperature parameter can be set on the panel.

(2) Failure analysis: ① The oven can be powered on as a whole, and the temperature controller panel can also be operated. It is suspected that the heating tube is damaged. Use a multimeter to measure the resistance of the heating wire, which is about 10 Ω, which should be normal. ②Set the target temperature on the thermostat to 70 °C, measure the voltage at both ends of the heating wire, and find that it is 0 V. Further measure the output voltage of the thermostat, and the output is 0 V. Then make a judgment that the thermostat is damaged. The thermostat model is XMTD8401, which adopts single-chip microcomputer technology, switching power supply, and has the functions of temperature control, timing, and over-temperature alarm.

(3) Problem solving: In order to repair the oven as soon as possible, the controller was not opened to repair the components, and the temperature controller of the same type was directly replaced, and it started to run normally after replacement.

3 Conclusion

In order to prolong the service life of the electric Forced Air Drying Oven, in terms of maintenance and maintenance, the interior of the box should be wiped and cleaned regularly, and volatile and corrosive products cannot be placed in the working room. Regularly check whether the fan of the electric Forced Air Drying Oven is running normally. If there is any abnormal sound, immediately shut down the machine for inspection. Regularly check whether the vents of the drying box are blocked, and regularly clean up the accumulated dust.