Punching device making large rectangular holes in rectangular tubing and method thereof

A punching device for punching rectangular holes in a longitudinally extended rectangularly shaped tubular workpiece, said punching device comprising;

• a mandrel extending in a longitudinal direction and configured for removably receiving the workpiece sleeved thereon, said mandrel including a two-sided die positioned thereon;
• a rectangular punch disposed in correspondence with said two-sided die;
• a first fluid driven ram configured to displace said rectangular punch through a selected side wall of the workpiece and into said two-sided die, the rectangular punch displacement defining a punch direction;
• and
• a second fluid driven ram configured to displace a piston rod into compressive engagement with a respective portion of one of a pair of opposing side walls of the workpiece adjacent the selected side wall in correspondence with said two-sided die, another respective portion of the other of the pair of opposing side walls of the workpiece being disposed in correspondence with said two-sided die and being in juxtaposition with a supporting member, and said second fluid driven ram being displaced in a direction transverse with respect to both the longitudinal and punch directions to apply a compressive force to the respective portions of the pair of opposing side walls of the workpiece adjacent the selected side wall, the compressive force being of a magnitude to elastically deform the workpiece in a range of 0.015-0.020 inches and thereby support the side walls of the workpiece against deformation thereof during punching.

A punching device for punching rectangular holes in a longitudinally extended rectangularly shaped tubular workpiece, said punching device comprising;

• a mandrel extending in a longitudinal direction and configured for removably receiving the workpiece sleeved thereon, said mandrel including a two-sided die positioned thereon, said two-sided die including a die opening formed in said longitudinally extended mandrel, a pair of tool steel die pieces affixed to opposing longitudinal ends of said die opening, and a protrusion extending from a bottom surface of said two-sided die into said die opening between said pair of tool steel die pieces;
• a rectangular punch disposed in correspondence with said two-sided die, said punch including a recess formed in an end surface of a cutting end of said rectangular punch and in correspondence with said protrusion of said two-sided die to shape a slug punched from the workpiece;
• a first fluid driven ram configured to displace said rectangular punch through a selected side wall of the workpiece and into said two-sided die, the rectangular punch displacement defining a punch direction;
• and
• a second fluid driven ram configured to displace a piston rod into compressive engagement with a respective portion of one of a pair of opposing side walls of the workpiece adjacent the selected side wall in correspondence with said two-sided die, another respective portion of the other of the pair of opposing side walls of the workpiece being disposed in correspondence with said two-sided die and being in juxtaposition with a supporting member, and said second fluid driven ram being displaced in a direction transverse with respect to both the longitudinal and punch directions to apply a compressive force to the respective portions of the pair of opposing side walls of the workpiece adjacent the selected side wall, the compressive force being of a magnitude to elastically deform the workpiece and thereby support the side walls of the workpiece against deformation thereof during punching.