PURPOSE: To form a longitudinal raised line on a flat seal part in order to permit the visual check on changes in the seal pressure, by providing seal rolls for effecting an longitudinal seal with a surface for forming a lattice-shaped depressed and raised seal and a flat seal forming surface, both in a predetermined width, and by providing a groove for forming a raised line on the flat seal forming surface.
CONSTITUTION: A heat seal part 5a of each of a pair of longitudinal seal rolls 5 adapted for forming a longitudinal seal part 6 has a seal forming surface 14 provided with lattice-shaped depressed and raised portion for forming lattice- shaped seal 6a and a flat seal forming surface 15 for forming a flat seal 6b. The flat seal forming surface 15 is provided with a groove 16 for forming a raised line 6c. A folded film sheet 1 is heated at both sides thereof by the longitudinal seal rolls 5, whereby the interior low temperature fusible films 2 are gradually fused together and the superfluous film is forced out of the sealed area and forced into the raised line 6c formed on the exterior low temperature non-fusible film 3 by the groove 16.
JPS617149U | 1986-01-17 | |||
JPS6254663A | 1987-03-10 | |||
JPS39577Y1 | ||||
JPS5332869U | 1978-03-22 |
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