| 摘要 |
<p>A wide web of heat-sealable plastic material, continuously unwound from a supply roll, is slitted longitudinally into a plurality of parallel strips which are entrained by a motor-driven traction roller and are allowed to hang in slack loops about one or more horizontal bars carried on the free end of a sensing lever, being then fed past an intermittently operating clamp and a drawing mechanism to an output stage where they pass through a set of friction rollers or rods and are periodically pulled forth for shaping into envelopes sealed about materials discharged from respective dispensers. With the drawing mechanism intermittently picking up the slack of the loops, the length of the shortest loop controls the position of the sensing lever which, on swinging beyond an upper or a lower limit, coacts with one of two stops to accelerate or retard the drive motor, thereby maintaining a proper average feed rate.</p> |
