Ultrasonic welding method for metal and plastic

The invention provides a metal and plastic ultrasonic welding method which comprises the following steps: S1, processing a groove on a to-be-welded surface of a plastic plate, and processing a plurality of trapezoidal bulges on a to-be-welded surface of a metal plate; s2, the face, where the groove is located, of the plastic plate is placed upwards, the part, where the groove is not machined, of the plastic plate is located below a welding head, and the welding head can press the surface of the part, where the groove is not machined, of the plastic plate; s3, the welding head is lifted up, the plastic plate is placed on the cutting board, and then the part, provided with the trapezoidal protrusions, of the metal plate is placed in the groove of the plastic plate; s4, the welding head is lifted up, welding parameters are set, and welding is started; and S5, plastic, extruded out of a weld joint in the welding process, on the workpiece after welding is completed is cleared away. According to the method, the mec