Method for pressing groove section with bending angle smaller than or equal to 90 degrees

A method for pressing a groove section with a bending angle smaller than or equal to 90 degrees, comprising:

• 1) assembling an upper die assembly on a stamping mechanism connected with an expansion core of the upper die assembly, and laying a flat-plate type workpiece to be processed at an upper port of the lower die assembly;
• 2) descending the stamping mechanism to drive an expansion sleeve and the expansion core of the upper die assembly to descend synchronously, wherein the expansion sleeve is contacted with the workpiece to be processed firstly during the descent;
• further descending the stamping mechanism, wherein the expansion core is further driven to descend while the expansion sleeve stops moving during the further descent since a stamping force of the stamping machine does not reach yield strength of the workpiece to be processed at this time, an elastic part in a chute of the expansion core is shrunk, and the workpiece is not bent;
• and expanding the expansion sleeve when the expansion core is descended to a bottom of the expansion sleeve, wherein the expansion core is contacted with the workpiece to be processed;
• 3) further descending the stamping mechanism wherein the stamping force of the stamping machine exceeds the yield strength of the workpiece to be processed, and the expansion sleeve and the expansion core bend the workpiece together to allow the workpiece to enter a groove of an inner concave die;
• 4) further descending the stamping mechanism, wherein the inner concave die is descended when the stamping force exceeds a resistance of an elastic body at a bottom of the inner concave die, the inner concave die is compressed inwards by an outer concave die along with descent of the inner concave die, and when the inner concave die is descended to a termination point at the bottom of the outer concave die, the workpiece is tightly extruded and hooped on an outer wall of the inner concave die to form a preset grooved part;
• and
• 5) the elastic body at the bottom of the inner concave die being subjected to elastic recovery to bounce the inner concave die upwards;
• meanwhile, the elastic part in the chute of the expansion core recovering deformation;
• and the expansion core and the expansion sleeve relatively moving to recover to initial states;
• wherein along with continuous ascent of the inner concave die, a groove width of the inner concave die is gradually enlarged, after the elastic body completely recovers the deformation, the inner concave die recovers to an initial position, the expansion sleeve and the expansion core are taken out of the groove of the inner concave die of a lower die assembly under a pull-up force of the stamping mechanism, and then the workpiece is taken out.