Patent ID: 6519917
Filing Date: 2003-02-18
Classification: B29C,B29K,B29L,B31B,B65B,B65D

Abstract:
A method of making a flexible gusseted package formed from a continuous web of substantially constant thickness packaging material characterized by having front and rear faces and at least one gusseted side extending between said front and rear faces, a repeatably openable and reclosable arrowhead shaped interlocking seal operative to open and close said package body to provide and prevent respectively access to the package interior, said reclosable interlocking seal extending through said front and rear faces and at least one gusseted side of said package and comprising in combination, inner and outer interlocking portions, the inner and outer portions of said seal in at least said front and rear faces of said package each comprising one thickness of said flexible packaging material secured to at least one discrete strip of substantially constant thickness flexible material, comprising the steps of,a) transporting in lengthwise direction a web of flexible packaging material of selected width and indeterminate length having at least one thermoformable strip of a length substantially greater than the strip width affixed to the web with the strip length oriented transversely to the running length of the film at package length intervals, b) passing said film over a forming collar and around a cylindrical forming tube and forming a longitudinally sealed cylindrical tube of packaging film with the said at least one thermoformable strip inside the film tube, and with the surface of the said at least one strip not secured to the film being in facing relationship within the tube, c) moving the film tube past a gusseting tool to provide a pair of opposite side gussets in the tube, d) moving the portion of the gusseted tube within which the strip is disposed between a pair of spaced apart heated interfitting male and female forming dies respectively having an inner male projection and a complementally shaped female recess, e) moving said dies toward one another to press the face of the said at least one strip not secured to the film against itself to form two apposed strip faces extending at least partly across the film tube, and continuing to move said dies toward one another into mating position and forming the central part of the strip extending across the film tube into the recess of said female die to form a tip of the arrowhead shape of the reclosable seal, f) moving toward one another into closed position a pair of interlock forming heated dies positioned at opposite sides of the female die to press portions of the margins of the strip immediately adjacent to the central part of the strip inward against one another to form inwardly sloping bottom surfaces to complete the inner male and outer female parts of the reclosable interlocking seal held between the female die and the pair of interlock forming heated dies while partially retracting the male die, and g) fully retracting the male and female dies to their initial positions.