| CPC B65H 20/02 (2013.01) [B31B 50/44 (2017.08); B31B 50/72 (2017.08); B65H 23/16 (2013.01); B65H 23/28 (2013.01); B31B 50/26 (2017.08); B31B 50/724 (2017.08); B31B 50/726 (2017.08); B31B 2100/00 (2017.08); B31B 2100/0024 (2017.08); B31B 2110/30 (2017.08); B31B 2110/35 (2017.08); B31B 2120/502 (2017.08)] | 16 Claims |
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1. An unwinding unit for unwinding a strip of heat sealing material for quadrangular machine for forming boxes from blanks of paper or cardboard, each blank having a base and a plurality of segments connected to the base, the unwinding unit comprising:
a casing mounted on the quadrangular machine;
a puller, associated with the casing and configured to pull the strip relative to the casing along a feed path and in a feed direction; a pair of counter-rotating rollers, configured and effective to act as a deformer to make a crease line on the strip as the strip is passing between the pair of counter-rotating rollers;
a diverter, configured to divert the strip between an initial, horizontal stretch of the feed path and a final, vertical stretch of the feed path oriented in a vertical direction perpendicular to the feed direction, wherein the diverter extends between an inlet portion, oriented horizontally and receiving the strip at the initial, horizontal stretch of the feed path, an outlet portion, oriented vertically and delivering the strip at the final, vertical stretch of the feed path, and an intermediate portion, located between the inlet portion and the outlet portion, the intermediate portion having a curve shape to define a curved, connecting stretch between the initial stretch and the final stretch,
wherein the rollers of the pair of counter-rotating rollers are thrusted one against the other through a force which keeps said counter-rotating rollers (A) in contact with the strip passing therebetween, and (B) pushed one against the other,
wherein the pair of counter-rotating rollers is located in a transit zone between the initial, horizontal stretch of the feed path and the final, vertical stretch of the feed path,
the unwinding unit further comprising a body located downstream of the diverter with respect to the feed path, the body providing an outfeed guide, to guide the strip along an end portion of the final stretch of the feed path and to position a portion of the strip to vertically face a corner edge of a box, wherein the body extends vertically between an upper end and a lower end and is internally provided with a through gap, the strip sliding in the through gap, wherein the through gap extends vertically from a gap inlet to a gap outlet located at the location where the strip exits the through gap,
wherein the body has a bottom face laying in a horizontal plane perpendicular to the vertical direction, the bottom face defining the lower end of the body and elongating in a transversal direction, perpendicular to the vertical direction and to the feed direction, and wherein the outlet of the through gap is located at the bottom face of the body, at the location where the strip exits the outfeed guide, and has a “V” shape, with a concavity oriented in the feed direction; wherein said body includes an inner portion and an outer portion removably fixed to one another and providing a recess and a protrusion, the recess and the protrusion being counter-shaped and spaced one from the other to form the “V” shaped through gap.
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