Patent ID: 7513922

Claim:
An air filter for electric welding comprising: a box provided with a dividing plate to divide said box into an upper chamber and a lower chamber, an opening at its top wall for connecting with a sucking tube, a sidewall provided with a plugging groove at the top, and a rear wall of said lower chamber provided with an opening; said dividing plate provided with a penetrating hole at the center to communicate with said upper chamber and said lower chamber; a spark blocker fitted in said plugging groove of said box to seal the top side of said upper chamber; a movable filter device being installed inside said upper chamber and comprising of a first rolling base, a second rolling base corresponding with said first rolling base, a rolling table and a rolled cloth filter winder; said rolling table comprising of: a frame fixed under said spark blocker inside said upper chamber; a first axle fixed at one side of said frame and provided with a driving gear respectively at two ends and a driven gear set outside one end of said driving gear; a second axle fixed at the other side of said frame and provided with a driving gear respectively at two ends, a driving motor fixed on said frame and provided with a power-output shaft installed with a driving gear; a first chain mounted between said driving gear of said driving motor and said driven gear of said first axle and able to transfer power to said first axle; two second chains respectively mounted between said driving gear of said first axle and that of said second axle at the same side and driven by said driving gears of said first axle to rotate; and plural supporting rods connected between said second chains and spaced apart with a preset distance and driven by said second chains to move in a circulating condition, forming a rolling rods unit; said first rolling base and said second rolling base respectively installed on two sides of an upper surface of said dividing plate, said rolling table fixed under said spark blocker inside said upper chamber and having a circulating rods unit, said rolled cloth filter winder provided with a first shaft connected pivotally with said first rolling base, a second shaft connected pivotally with said second rolling base, a rolled cloth filter mounted around said first shaft and provided with a free end able to be pulled outwards to pass over said rolling table to get wound around said second shaft, said cloth filter also laid and moved on said rolling table; a blower installed inside said lower chamber of said box and provided with a sucking opening connected with said penetrating hole of said dividing plate, and at least an air exit; and an extractable screening device installed outside said opening of said rear wall of said box and provided with a frame having an interior space, an entry and an exit, a filtrating screen set above said frame and having at least a screen located between said entry and said exit for screening air sucked in, said entry communicating with said exit and said opening of said lower chamber.