No matter how you apply a layer of plastic film on a plastic woven bag, it will become airtight. At that time, when using this kind of laminated plastic woven bag, it was necessary to ensure that the cement was filled in time under the action of a certain wind pressure during filling, and it was also necessary to achieve moisture-proof purposes during transportation, loading, unloading, and storage. At present, micro holes can only be pierced on the surface of the laminated plastic woven bag, and there is no other technical method that can replace it. Composite plastic woven bags are the same as other structural packaging bags. In addition to meeting the basic functions of packaging cement, they also need to solve exhaust problems, temperature resistance problems, and moisture-proof problems during cement filling. The perforation problem of laminated plastic woven bags is the key to solving these technical problems.
Most cement companies use gas-transported cement filling methods during cement filling. The exhaust problem during cement filling is not properly handled. First, it affects the filling efficiency. Second, the bag weight qualification rate does not meet the requirements. For laminated plastic woven bags, we must also consider the phenomenon of running, leaking, and ash leakage during filling, as well as moisture-proof problems during transportation and use. The exhaust holes are large, the number of holes is large, the exhaust function is good, and the filling efficiency is high, but the cement leakage is serious during filling, and the moisture-proof function is poor; the exhaust holes are small, the number of holes is small, the exhaust function is poor, and the filling efficiency is poor. The power is low, but there is less cement leakage during filling, and the moisture-proof function is also good. Therefore, the size and density of the needle holes are key to the phenomenon of ash leakage during cement filling and the moisture resistance of the cement. The diameter of the needle is 2mm or 1. 5mm, which can meet both requirements. The general operation is: to put a needle hole every 6mm in the longitudinal direction of the laminate cloth and a needle hole every 8mm in the transverse direction. Use a tapered needle for the punching needle, and use the method of drilling from the inside out for the exhaust hole.