METHOD AND DEVICE FOR MANUFACTURING PIPE OF PIPE PUNCHING MACHINE

摘要

PURPOSE:To manufacture long-sized pipes at high yield in a short time by performing punching at a low rate of reduction in the early stage by using a mandrel inserted into a tubular body whose front end is reduced in diameter by swaging work, and then by increasing a punching speed. CONSTITUTION:The front end 4 of a tubular body 1 is reduced in diameter in a conical shape so that the angle of the cone is 22-28 deg., and then a mandrel 2 is inserted into this tubular body 1. Then, the tubular body 1 is moved forth by the mandrel 2 until it comes into contact with the 1st die 6, and further the mandrel 2 is advanced slightly into the die 6; and the end is moved invard to decrease its minimum internal diameter. Therefore, the supporting section between the mandrel 2 and tubular body 1 is increased to transfer high punching force. Then, the supporting section is furthr increased at the 2nd stand 7 and the hole punching force is transferred at the 3rd stand 8. Namely, a small amount of material is used for the swaged part, so that loss of material due to the swaging work is small, improving the productivity of long-sized pipes on the whole.