Apparatus for testing for leaks in a gas-filled pack is placed in a packaging line and comprises two upper conveyors (10A, 10B), each connected to a load cell (12A, 12B) and positioned above a lower, synchronized conveyor (8). A gas-filled pack on the lower conveyor (8) passes under and is compressed by the first and second conveyors (10A, 10B), in succession, the pack being detected by sensors (16) connected to a control unit (6) which causes the force required to displace the pack lid to be measured by a respective load cell (12A, 12B) at regular intervals of travel. A microprocessor determines from a comparison of the two force/displacement relationships so generated whether the pack leaks. In an alternative arrangement using just one load cell, the lid of the pack is displaced by a vertically reciprocal load cell whilst the load cell is moved along the packaging line by a chain drive moved at the speed of a pack by a stepper moter. When the vertical return stroke of the load cell is completed the actuator and load cell are returned to their initial horizontal position.
|Patent number||GB2234076 (A)|
|Publication status||Published - 23 Jan 1991|