Punch die’s fixed error
China CNC machining For the all classes of dies, if we analyse the fluctuate, tendency of increase and decrease and law which appeared in the die’s whole life, we will find that the master of the error are changeless; the error that because the abrade of the cutter and impression will be as the cutter grinding times increased at the same time. And that will cause the error oversize gradually; and also have another part error are unconventional , unforeseen. Therefore, every die’ s error are composed of fixed error, system error, accident error and so on.
1. fixed error
China CNC machining At the whole process when the New punching die between just input production to discard, the changeless master error that in qualified part are called fixed error. It’s magnitude is the deviation when the die production qualified products before the first cutter grinding. Also is the initial error, but the die have initial punching accuracy at this time. Because of the abrade of parts, the die after grinding will be change the dimension error. And the increment of deviation will oversize as the times of cutter grinding. So the punching accuracy after cutter grinding also called “grinding accuracy” and lower tan initial accuracy. The fixed error depend on the elements factor as followed :
(1) the material , sorts, structure, (form) dimension, and thick of panel
China CNC machining the magnitude of punching gap and degree of homogeneity are have a important effect for the dimension accuracy. Different punching process, material, thick of panel, have completely different gap and punching accuracy. A gear H62 which made in yellow brass with the same mode number m=0.34,
thick and had a center hole, when the gap get C=0.5%t (single edge) , and punched
with compound punching die, and the dimension accuracy reached IT7, the part
have a flat surface ,the verticality of tangent plane reached 89.5°, its
roughness Ra magnitude are 12.5μm, height of burr are 0.10mm; and the punching part are punched with
progressive die, the gap C=7%t (single edge) , initial accuracy are IT11, and
have an more rough surface, even can see the gap with eyes. In the usual
situation, flushes a material and its thickness t is theselection punching gap
main basis. Once the designation gap haddetermined flushes the plane size the
fixed error main body; Flushesthe structure rigidity and the three-dimensional
shape affects itsshape position precision.