Application of switching power supply and thyristor rectifier in piston ring electroplating

　　Surface electroplating of piston rings has always been a widely used process. The high-frequency switching power supplies and graded thyristor rectifiers produced by the factory are widely used in electroplating in various industries across the country. Here are a few points to note for some technical issues.

　　1 About the power factor problem

　　The rectifier is graded in 9-level and 11-level. This rectifier transformer can greatly improve the power factor after being graded, and the power factor reaches above 0.93. Our factory successfully developed the S11 graded rectifier in 2002. The three-phase no-load current is 1.5A. The characteristics of this rectifier are: low temperature rise, low noise, high power factor, and ripple coefficient of 2%. The high-frequency switching power supply is a power supply made of IGBT ferrite and inverter circuit. As early as 1997, our factory provided Guangxi Zhonghuan Company with a switching power supply with a current of 2500A and a voltage of 0-12V. In actual use at that time, the switching power supply was increased to a current of 2300A. The voltage is 10.5V. At the same time, Guangxi Zhonghuan Company also has 4 ZDDKF-2500A0-12V thyristor rectifiers from our factory.

　　Under the same conditions of current, voltage and switching power supply, the actual use was nearly 5 hours, and the results were obvious. The high-frequency switching power supply can save 5% of electricity compared with 4 2500A thyristor rectifiers, but the deposition speed of the switching power supply is slow, and the surface hardness of the piston ring is not as high as that of the thyristor rectifier. The hardness of the switching power supply is 800-900HB. The surface hardness of the ring of the ZDDKF2500A thyristor rectifier can reach 1100HB. Later, Guangxi Zhonghuan Company still chose the ZDDKF with graded energy-saving rectifier.

　　Comparing the switching power supply and the graded rectifier, the total power of the switching power supply at 2000A12V is basically the same as that of the thyristor rectifier at 2000A. The power factor is not much different, and the power consumption is also equal.

　　2 Selection and comparison

　　Under the same conditions, high-frequency switching power supplies save 5% more power than thyristor graded rectifiers. However, the power deposition speed of switching power supplies is slow, and the surface hardness of piston rings is not as high as that of thyristor rectifiers. Domestic authorities recommend the use of thyristor rectifiers. Taiwan Chuanglin Company's piston ring manufacturers are also using thyristor rectifiers. German piston ring manufacturers also use thyristor commutation rectifiers. German experts say that the use of switching power supply electroplating technology is generally used in gold-imitation technology, precious metals, and watch industry electroplating. It can be seen that thyristor rectifiers should be used for piston ring electroplating.

　　3 Using commutation rectifier

　　In order to make the surface of the piston ring good, a commutation rectifier should be used. The operation process is as follows: first put the workpiece into the electroplating tank, and then use reverse current. Use a large current to impact within a few seconds to remove the impurities on the surface of the piston ring. After 15 to 20 seconds of large current impact, the surface quality of the piston ring is improved. Then return the reverse current to a certain rated value, and after working for a few seconds, the reverse current returns to zero. After 10 to 20 seconds of soft start, use the forward current again. This process has a good effect. In terms of power rectification, our factory has rich experience and is equipped with various products. We can help users design scientifically and use the rectifier power supply reasonably according to the production needs of the industry, so that it can play a role in production in an efficient, energy-saving and economical way.