Apparatus for differentially stretching, aligning and cutting sheet material
AssigneePPG Industries, Inc.
InventorJoseph Chabal
Life of this patent
Estimating the term…
Abstract
Differentially stretched plastic with a dyed border along one side suitable for shaded interlayers of laminated windshields moves in an arcuate path away from a frustoconical roll of a continuously operating differential web stretcher toward an intermittently operated web cutting machine, which tends to veer the web transversely every time it starts to pull a length of web into the cutting machine. The present invention realigns the arcuately shaped web between cutting operations when necessary to compensate for lateral veering of the arcuate plastic web from the arcuate path it takes so as to cause the web to enter the web cutting machine at a proper angle and orientation for cutting.
Claims7
Apparatus for stretching, aligning and cutting a continuous web of arcuately shaped, flexible material comprising:
- a differential web stretching station having first drive means to move said web at a continuous first speed along a curved path;
- a cutting station positioned along said curved path, spaced from said stretching station, said cutting station having a web cutting means;
- second drive means;
- timer means acting on said second drive means to intermittently drive a given length of web through said cutting station at a second speed greater than said first speed and acting on said web cutting means to cut a piece of a predetermined length from said web;
- and
- a web aligning device between said stretching station and said cutting station, said aligning device comprising:
- a pair of guide posts oppositely disposed on each side of said path;
- a rod;
- means for slidably mounting an end portion of said rod in each of said posts for movement from a first position in overlying relation to the upper surface of the path defined by the web as said web moves from said stretching station into said cutting station, towards and away from a second position in overlying relation to the upper surface of the path defined by a loop of the web as the web moves from said stretching station toward but not into said cutting station;
- stop means mounted at a first level in the path of a first end portion of said rod as the first rod end portion moves from the first position to the second position;
- and
- switch means operatively connected to said second drive means and said timer means and mounted at a second level vertically lower than said first level, in the path of a second portion of said rod as the second rod end portion moves from the first position to the second position;
- wherein the length of the loop increases to move said rod from the first position towards the second position when said second drive means is inactivated by said timer means, to move said first rod end portion into engagement with said stop means, to pivot said second rod end portion about said stop means into engagement with said switch means to activate said second drive means, to activate said timer means as said second drive means is activated, to move the web into the cutting station at said second speed to decrease the length of the loop, to pivot the second rod end portion about said stop means away from said switch means, to continue to move the rod toward the first rod position and thereafter move the first rod end portion away from the stop means as the rod continues to move toward the first rod position wherein the web, as the loop decreases, engages the second rod end portion, the rod portion between the first and second rod portions and thereafter the first rod end portion to provide tension on the web and to maintain web alignment as said second drive means moves a predetermined length of web into said cutting station after which said timer means inactivates said second drive means and activates cutting means to cut a piece of web having a predetermined length.
Dependencies are inferred from the claim text.