The process of PVC sealing in painting shop plays an anti-corrosion and sealing role.After drying,there will be a certain probability of cracking and non-bonding in the middle of the adhesive strip,which losing its anti-corrosion sealing effect.Through a large number of experimental investigation is determined to be due to the PVC glue in the drying process,the outer door plate and the inner plate heating time difference,the outer plate priority heating thermal expansion effect;at the same time,for the folding glue inside the door is too little to resist the stress caused by PVC glue cracking phenomenon.By grinding in advance,increase the amount of folding glue to solve the problem of cracking.