Exclusion of tearing fault at mouth of WH47 offset printing

The company's WH47 offset press has been used for many years, generally printing and copying paper, 250g/m2 coated paper and cardboard, etc. But when printing offset paper below 100g/m2, especially 28g/m2 paper, there is a small mouth of about 10mm at the mouth, and the cutting can not afford to leave, seriously affecting the quality of the printed matter. So immediately stop and check.

Firstly, the tooth pads, tooth chips, and tooth shafts of the delivery chain were examined one by one, and it was found that the individual tooth pads and tooth chips were worn badly. After replacing and repairing the machine, the machine turned on, but the printing was improved. However, the paper was changed below 40 g/m2. There is still a small mouth at the mouth. After repeated experiments, the author found that the transfer time between the impression roller and the chain teeth was incorrect, and the closing time of the chain teeth was longer than that of the roller open teeth. Remove the chain open jaws and found that the open tooth plaque wear is more serious. Repaired with gas welding, then smoothed with steel honing, re-installed opener, test machine, failure disappeared. However, attention should be paid when using gas welding repairs to be precise and accurate.

(Qinhuangdao Chenxin Color Printing Factory Zhang Chuncai)
Reprinted from: Printing Technology