Abstract Method and apparatus for transversely stretching sheet material wherein the material is moved in its longitudinal direction, tension is applied in the transverse direction, the material heated and uniformly stretched in its transverse direction at a rate sufficient to orient the material. After the material is uniformly transversely stretched the desired amount the edges of the material are kept parallel and the material cooled. The apparatus comprises means for applying tension in the transverse direction of continuously moving sheet material, means for heating the material while said tension is applied, a pair of diverging conveyors which diverge at an angle greater than 40*, the diverging conveyors having clamping means which clamp the edges of the material to uniformly transversely stretch the material as the conveyors diverge and means for removing the continuously moving sheet material from the clamping means of the diverging conveyors while maintaining the edges of the material substantially parallel and under control.
Apparatus according to claim 1 wherein the clamping means about one another along the entire length of the conveyor and each clamping means has a length of less than 3 inches.
Claim 2
Dependent Claim
19 words
Apparatus according to claim 1 wherein the clamping means are mounted substantially on the pitch line of the conveyor.
Claim 3
Dependent Claim
22 words
Apparatus according to claim 1 including means for maintaining the clamping means deactivated until returned to the start of the first flight.
Claim 4
Dependent Claim
23 words
Apparatus according to claim 1 including means for increasing the longitudinal speed of the material as it is released by the clamping means.
Claim 5
Dependent Claim
109 words
Apparatus according to claim 1 wherein the means for immediately gripping the material as it is released and conveying the material away from said second flight comprises two sets of a pair of grooved, endless rubber belts, the belts of each set positioned with the lower flight of one belt immediately above the upper flight of the other belt of said set and with the grooves in the belts intermeshing, one of said sets adjacent the position of the second flight of one conveyor at which the material is released and the other set adjacent the corresponding position on the other conveyor, said sets being parallel to each other.
Claim 6
Dependent Claim
19 words
Apparatus according to claim 6 wherein the clamping means are mounted substantially on the pitch lines of the conveyors.
Claim 7
Dependent Claim
37 words
Apparatus according to claim 6 wherein the clamping means are mounted substantially on the pitch lines of the conveyors and means for increasing the longitudinal speed of the material as it is released by the clamping means.