I would like to share the reasons and solutions of some nonconforming fasteners and bolts. I hope it will be helpful to you.
1.Inner hexagon, outer hexagon head R Angle has wrinkles
● There is a risk of breakage after heat treatment and electroplating.
● During cold heading debugging, the R Angle of the first sequence die should be 0.1-.02 wire larger than the R Angle of the last sequence die. Only when the product has no wrinkles can it be produced.
● Such as :GB70-76 M8*20 head R Angle 0.5, 3 sequence 0.5 then the second sequence mold R Angle 0.6.
2.There are long and short bolts with chamfered corners
● How can this rub and did not beat the corner of the rub silk as long as dozens of silk out of tolerance so much.
● Such as: 5783M10x1.5 (pitch) X20 long, chamfering should be smaller than the light nail (cold heading diameter) minus the pitch is about 0.3-0.5 wire. ￠8.91-1.5-0.3=￠7.11. If the chamber is greater than 7.41, the yarn will be ￠8.91-1.5=7.41.
3.Cold heading is not produced according to the blank diameter of the process, and the blank diameter is not only small but also large
● The blank diameter is small stop more than: timely modify the mold, to meet the process requirements.
The billet diameter is large through the gauge impassability: timely replacement of new mold.
●(In special cases, if the blank diameter is large or small, as long as the product is rubbed on site to meet the requirements of the wire rolling process, the product can be released for production, but it can be produced after confirmation by the relevant person in charge).
● Die sleeve and die core pressure clearance fit will affect the size of the blank diameter.
4.Bolt chamfering wear, slight wear, serious wear
● Detection means mainly rely on visual inspection training.
● Slight wear can continue to produce but at any time to observe the quality of the product.
● Serious wear and tear in time to stop maintenance mold or replace the new mold.
● Quenched black products can barely, blue and white zinc, color zinc certainly not.
● The chamfer appearance of wear is too ugly, and the total length will be long when the wire is rubbed.
● Serious wear of chamfering die to timely maintenance or replacement, do not fight, affect the brand image.
5.Outer hexagonal, inner hexagonal billet diameter hair
● Raw material hair.
● The skin film is not good.
● Raw material rust
● Feeding wheel hair.
● a sequence of shrinkage die wear.
● Two sequential die wear.
The wire mold and the scissors mold are not adjusted well.
● The clip is not properly adjusted.
● the diameter of the pre-sequence billet is larger than the diameter of the post-sequence billet.
● Seriously affect the risk of dental cusp crack.
