Abstract: A method for combining a golf club head and a ball striking plate, includes the following steps: letting an outer edge of a ball striking plate and an inner edge of a recessed seat of a golf club head incline outward matingly, and forming an annular welding flange around a periphery of the recessed seat of the golf club head; using at least one press block to press the welding flange of the golf club head to form a deformation; using a high energy welding manner to melt and join an interface of the golf club head and the ball striking plate; and trimming the welded interface of the golf club head and the ball striking plate.

Abstract: A screw-rotor machine with two meshing rotors provides with helical lands and intervening grooves and adapted for rotation around parallel axes in a working space in the machine, characterized in that; the profile of rotors uses ellipse as a basic geometry generating curve on the male rotor.