The performance of motor shell decides to use pig iron instead of wrought iron: because wrought iron is rarely used as structural material, it is because of its soft texture and low strength. The carbon in cast pig iron exists in the form of flake graphite, and its fracture is gray, which is usually called gray iron. Because graphite is soft and has lubricating effect, cast pig iron has good cutting, wear resistance and casting properties.
Numerical simulation method is used to analyze and judge the thermal balance equation and shrinkage cavity of the micromotor casing, and the machining work of the center is completed. Use colorful graphics or pictures to analyze the dynamic performance of computer results. During the casting process of motor shell, attention shall be paid to the pouring position, bisector, riser, chill and other processes. The bottom pouring system can be selected, which is conducive to mold exhaust and scum floating.
What is the cause of leakage in Dalian motor case
(1) Extended service of household appliances
Each electric appliance has its own service life. Nowadays in China, especially in villages and towns, low-income families have some electrical appliances that have been used for too long, beyond their normal service life. Generally, after the appliance has passed the service life, the electrical components will age, and the internal insulation of the appliance will age. Under the condition of moisture, the insulation resistance inside the appliance will be reduced, which will form leakage and cause damage to the personal safety of the user. Therefore, consumers should try their best to prevent the extended service of household appliances and let the old appliances leave their posts on time.
(2) When the insulation of the connecting wires and parts inside the appliance is damaged or severely affected by moisture, the insulation resistance will be greatly reduced, resulting in leakage of the appliance shell.
(3) Insulation damage or severe pollution of internal terminals of electrical appliances. When the insulation resistance decreases severely, the electrical enclosure will be charged.
(4) Electric household appliances operate under low voltage (below 187v) for a long time and overload for a long time; Poor heat dissipation may cause the motor temperature to be too high, resulting in premature aging of insulation, resulting in lower insulation resistance of the motor and electrifying the shell of the electrical appliance.
The waterproof test fixture of motor shell is to realize the waterproof grade test of motor shell. Test method: use direct test method. Due to the particularity of the motor shell, it is necessary to customize the tooling to install the mold, put the product into the mold, press the upper mold down to fix the product, and carry out the test. The test pressure is 250kPa, the inflation time is 10 seconds, the stabilization time is 10 seconds, the test time is 5 seconds, and the leakage value is 50pA.
Connect the metal shell of the electrical appliance to one pole of the ordinary incandescent bulb, and the other pole of the bulb to the earth or the zero line of the power supply: if the bulb does not light, it usually belongs to the normal power supply; If the brightness of the bulb is the same as that of the 220V communication power supply, the internal insulation of the appliance is broken; If the bulb is darker than when connected to 220V communication power supply, the electrical insulation is poor. The latter two types of electrification belong to abnormal electrification of electrical appliances.
