다이오드 어셈블리를 이용한 인버터 저항용접기의 성능에 관한 연구

Abstract

본 연구에서는 저항 스폿용접기의 변압기용 다이오드 정류기를 대용량의 전류를 정류할 수 있으면서도 외형의 크기는 줄일 수 있도록 하며, 안정적으로 냉각시킬 수 있도록 하는 저항 스폿 용접기의 변압기용 다이오드 어셈블리를 제공하는 데 그 목적이 있다. 따라서 다이오드 어셈블리 냉각을 개발하기 위하여 인버터 저항용접기의 변압기용 다이오드 어셈블리를 구성하였고, 다이오드 정류기의 냉각을 위해 공랭식 냉각장치와 수냉식 냉각장치를 비교하기 위하여 공랭식 냉각시스템, 방열판 재질에 따른 공랭식, 수냉식 냉각시스템, 대류 조건에 따른 수냉식 냉각시스템에 대한 유한요소해석을 하여 최적의 냉각시스템을 결정하였다. 또한, 기존의 저항 스폿용접기를 이용한 용접 결과와 인버터 프로젝션 공법이 적용된 용접 결과를 Leak 시험, 강도시험, 필 시험, 인장시험을 통해 최적의 용접법을 결정한 연구이다.|With the development of the industry, there is an urgent need to streamline welding work and to improve welding quality. Accordingly, in order to reduce the size and weight of the electric resistance welding machine, the inverter control technology, which was mainly applied to the existing resistance welding machine, was applied to the resistance spot welding machine. Currently, resistance spot welding machines are developed in industrially developed countries and are being used in industrial sites, but development is insufficient in Korea. There are various types of resistance welding machines according to welding method, pressurization method, form, current conduction method, and power supply method, but this study is about inverter type resistance spot welding machine among resistance spot welding machines.[1] In general, inverter resistance spot welders are welded using DC current. Resistance welding is a device that converts electrical energy into a high-temperature arc, which is a form of thermal energy, and melts and bonds the base material, and is widely used in industrial sites. The resistance welding machine currently used has used a diode rectifier as a DC power supply. The diode rectifier has the disadvantage of lowering the power factor of the input side of the welding machine by containing a large amount of low-order harmonics in the input current. In addition, a high voltage is required to improve the performance of the resistance welding machine. In general, a transformer is used to boost the current. And in order to stably implement high voltage, the rectification process must be stable.[2] However, heat is generated in the diode during the process of rectifying AC current to DC current by the diode rectifier, and if it is overheated, the performance of the resistance welder may be unstable or a fire may occur. In order to prevent this, the external size of the diode assembly was made very large by the current capacity required when outputting a high voltage current. For example, there is a problem in that it is provided in a size of about 50cm to 100cm and occupies a wide occupied space. In addition, conventionally, as a method for cooling the diode rectifier, there have been cases in which an operator manually pours water or turns on a blower to cool it, and this method has a very unstable and inconvenient problem. Currently, studies on inverter resistance spot welding according to current, pressing force, and energization time are being conducted in various ways, but research on the effect of the cooling conditions of the rectifier diode assembly on the welding characteristics has not been conducted. In the industrial field, it is recognized that the quality of the product produced is actually different depending on the cooling condition of the welding machine. In this study, through an experiment, the diode rectifier for transformer of the inverter resistance spot welder is able to rectify a large amount of current, while reducing the size of the external shape and stably cooling the transformer diode assembly of the inverter resistance spot welding machine. Its purpose is to prove and provide.