Head end hot melting device for liquid filter bag

The utility model relates to a filter bag producing and processing device, in particular to a head end hot melting device for a liquid filter bag. The welding machine comprises a base, a machine shelland a hot melting welding mechanism. The hot melting welding mechanism comprises an air cylinder, an ultrasonic transducer, a welding head and a welding base which are sequentially distributed from top to bottom. A cylinder body of the air cylinder is fixed in the machine shell. The ultrasonic transducer is fixed to the telescopic end of the air cylinder. The welding head is connected to the ultrasonic transducer; the welding seat comprises a vertical plate fixed on the base and a columnar mold which is vertically fixed in the middle of the vertical plate and is used for sleeving a supportingring of the filter bag; a receding groove for containing a handle on the filter bag supporting ring is formed in the end face of the end, opposite to the vertical plate, of the columnar mold, an arc-shaped welding groove with