METHOD OF MANUFACTURING CLOSED FRAME

摘要

A method for manufacturing a closed frame is provided to improve work and economic efficiency by performing a punching process continuously. A method for manufacturing a closed frame is as follows. A plurality of press machines having one or more punches(10) on the leading end of pressing direction are set up in the moving direction of a board(2). The punch comprises a double cutting blade(11) formed in closed type phase on the inside and outside. As the board moves, the press machines successively press the board. The cutting blades of the punches advance the board gradually deeper because the press machines press the same area of the board. The board is cut by punching with the cutting blade. The outside surface of the cutting blade is tapered to become thicker from the leading end. The inside surface of the cutting blade cutting the exterior of the frame is formed parallel to the pressing direction.