The invention relates to a preparation method of a fluxed core
welding ring. The preparation method comprises the following steps: preparing a thin strip 0.1-0.5mm think from a silver
brazing material containing 20-45% of silver, carrying out annealing treatment on the thin strip, washing the thin strip subjected to annealing treatment,
curling the thin strip by using a roller so as to deform to form a U-shaped strip with an upward opening, vibrating a silver
brazing agent to a conveying belt from a hopper, then conveying the silver
brazing agent to the U-shaped strip through the conveying belt, rolling the U-shaped strip by the roller so as to deform to form a butted tubular structure, flattening the tubular structure by rolling to form a flat
welding wire with a butted seam, cleaning the flat
welding wire with a
brush wheel and a hairbrush, and heating the flat welding wire through a low temperature
resistor and then carrying out looping forming. The active temperature of the silver brazing agent is 550-850 DEG C; the sliver brazing agent is formed by mixing the following components in percentage by weight of the total weight of the silver brazing agent: 35-37% of boric anhydride, 21-23% of
potassium fluoborate and 41-43% of
fluoride; the silver brazing agent accounts for 10-25% of the total weight of the fluxed core welding ring. The preparation method disclosed by the invention is concise and reasonable, the brazing process is simplified, the quality of a brazed joint is improved and the use cost of the brazing agent can be effectively reduced.