Patent ID: 7490448

Claim:
In form-fill-seal web packaging apparatus including a sealing station, a sealing machine for adhesively sealing upper and lower webs of a package at said sealing station, comprising upper and lower dies at least one of which is movable relative to the other such that said dies are relatively movable toward and away from each other to respectively engage and release said upper and lower webs therebetween and apply pressure to adhesively seal said upper and lower webs to each other, and a pressure monitor monitoring said pressure, and comprising an actuator actuating said one die to move toward said other die, and wherein said pressure monitor comprises a sensor sensing force applied by said actuator to said one die, wherein said sensor comprises a load cell through which said force is applied from said actuator to said one die, wherein said one die comprises a pair of parallel plates spaced by a plurality of load cells therebetween, a first of said plates being engaged by said actuator to transfer force through said load cells to the second of said plates to apply sealing pressure to said webs, said load cells being laterally spaced from each other and sensing even distribution of sealing pressure across said plates for uniform sealing of said webs, and sensing differential sealing pressure across said plates to detect nonparallel skewing of said plates relative to each other to in turn detect an obstruction at said webs.