Urania

Most pouch designs require the operator to hold the open end of the pouch tight and closed as the pouch enters the heat sealer during manual operation. If the pouch is not held closed, the material will bunch up, resulting in poor quality seals. To run these pouches automatically, a method to close the pouches as they enter the sealer is required. Urania Engineering has developed a system to simulate the manual pouch sealing operation.

The pinch and pull mechanism is an air powered device mounted to the entrance to the heat sealer. It utilizes an optical sensor to determine the leading and trailing edges of the pouch. As a pouch approaches the entrance to the heat sealer, the leading edge of the pouch blocks the pinch and pull optical sensor. The leading edge of the pouch activates the system. The pinch and pull waits for the trailing edge of the pouch to unblock the sensor. When the trailing edge unblocks the sensor, the sealer Programmable Logic Controller (PLC) activates the pinch and pull mechanism. The system is set that the trailing edge of the pouch unblocks the sensor as the leading edge of the pouch is firmly held between the seal belt in-feed rollers at the sealer entrance.

The first action is to close the pincher mechanism on the trailing edge of the pouch. Typically, the system is set to close on the last three quarters of an inch (0.750") of pouch material. This is enough to securely grab the trailing edge and ensure that variances in pouches do not allow the pinchers to miss the pouch.

When the pinchers are closed on the trailing edge of the pouch, the pouch is being pulled forward into the sealer due to the ‘grip' of the in-feed rollers. The pinchers offer restriction to the forward motion of the pouch. This restriction causes the pouch to pull tight and eliminate creases. The amount of restriction to forward motion of the ‘pinched' trailing edge of the pouch is adjustable. The pinch carriage will be pulled forward by the pouch after the pouch has completely tightened. This ‘pull' will be maintained until the carriage engages a sensor near the end of its stroke. The input of the sensor will cause the pinchers to open and be returned to their ‘home' position by means of a carriage return cylinder. The cycle will be repeated on the next pouch. The system relies on the pouches being presented to the Pinch and Pull Mechanism on a Conveyor in a uniform fashion. Pouch compatibility with the Pinch and Pull Mechanism and Conveyor must be determined before considering this effective option.