PRODUCTION OF DRAWN SQUARE TUBE FOR CONNECTING STEEL FRAME

PURPOSE:To obtain a good quality having no weld zone without the need for a die by forming a square steel tube of the diaphragm for building in a four face tube by pressing, etc., and adequately cutting the unnecessary part of this four face drawn tube in a three face drawn tube or two face drawn tube. CONSTITUTION:A four face drawn tube 5 is formed by a press by using outer and inner dies for a square steel tube. The right angled face having the side 6-3 of a drawn face 5-3 as its one side for the drawn face 5-1 of the four face drawn tube 5 is taken as 5-5. The crossing lines of the face 5-5 and face 5-1, the face 5-2, the face 5-4 are respectively taken as 6-1, 6-2, 6-4. The parallel line to the line 6-1 in the necessary dimension L from the line 6-1 on the choke face 5-1 is taken as 6-5 and the right angled face with the choke face 5-1 with the line 6-5 as its one side is taken as 5-6. The crossing lines of the face 5-6 and face 5-2, face 5-3, face 5-4 are respectively taken as 6-6, 6-7 and 6-8. A three face drawn tube is obtd. from the four face drawn tube 5 by cutting the crossing lines 6-1, 6-2, 6-4, 6-5, 6-6, 6-7 and 6-8 by a gas, etc.