The die consists of die frame, punch, die, locating pin, discharging rod, top plate, ejector pin and other parts. When working, the blank is positioned by two positioning pins on the top plate to ensure that it does not slip when bending. Complex bending die refers to the completion of more than two actions in one stroke. It can bend workpieces that simple bending dies can't bend.

The structure of the invention is characterized in that two pendulum blocks are installed on the lower die, and are bent and formed with the cooperation of the punch and the push plate. An inclined hopper is installed in front of the die, and the eccentric connecting rod mechanism is driven by the power of the crankshaft of the punching machine to feed the blanks in the hopper one by one, and the upper die part has an automatic discharging mechanism. A. radius of punch fillet

Generally, the working fillet radius of a punch is the inner bending radius of the bending part, that is, rt=r, but it cannot be less than the minimum bending radius allowed by the material. When the bending radius of bending parts is large, curvature springback should also be considered. If due to the structural needs of the workpiece, rrmin appears and then a shaping process is added, and the size of the shaping die is RT = R.

B. Radius of fillet of concave die

The fillet radius of the die should not be too small to avoid scratching the surface of the material. In actual production, the fillet radius of the concave die is usually selected according to the thickness of the material:

When t<2 Ra=(3~6)t

t=2~4 Ra=(2~3)t

t & gt4 Ra=2t

The bottom of the V-shaped female die can be opened and closed, or the radius ra of fillet is:

Ra = (0.6 ~ 0.8) (RT+T) When bending a U-shaped part, the size of the gap Z between the punch and the die directly affects the quality of the bent part. If the clearance is too large, the rebound angle will increase, and if it is too small, the thickness of workpiece material will become thinner and the service life of die will be reduced. In general, the gap value of the punch example can be calculated by the following formula:

Z=t+△+ct

Unilateral clearance of Z-shaped bending convex-concave die

T- material thickness;

△—— positive deviation of material thickness;

C- The coefficient determined according to the height of bending part and the length of bending line is generally 0.04 ~ 0. 15. The width dimensions of punch and die refer to the dimensions of Lt and La.