Apparatus for adjusting printing web tension

Claim 1

IN THE ART OF FEEDING A PRINTING WEB FROM A SUPPLY SECTION THROUGH AN ADJUSTING SECTION INTO A PRINTING SECTION, AN IMPROVED APPARATUS FOR MAINTAINING THE WEB ENTERING THE PRINTING SECTION AT A DESIRED SPEED AND UNDER A CONSTANT VALUE OF TENSION, COMPRISING: A. MEANS CONSTRAINING THE WEB TRAVELING THROUGH SAID ADJUSTING SECTION TO FORM A DOWNWARDLY DEPENDING U-SHAPED LOOP HAVING INCOMING AND OUTGOING WEB LEGS, (1) SAID MEANS INCLUDING A FLOATING-ROLLER GRAVITATIONALLY RESTING ON THE BIGHT OF SAID LOOP TO MAINTAIN THE WEB THROUGHOUT SAID LOOP UNDER A CONSTANT VALUE OF TENSION, (A) SAID FLOATING-ROLLER RISING AND FALLING VERTICALLY WITH SAID BIGHT AS THE AMOUNT OF WEB IN SAID U LENGTHENS AND SHORTENS WITH CHANGES IN THE RELATIVE SPEEDS OF THE WEB CONSTITUTING THE LEGS OF SAID U; B. A WEB FEED ROLLER BETWEEN THE SUPPLY AND ADJUSTING SECTIONS; C. PRESS DRIVE MEANS FOR CONTINUOUSLY (1) DRIVING THE PRESS, (2) DRIVING THE WEB BETWEEN THE ADJUSTING AND PRINTING SECTIONS BY PULLING WEB FROM THE OUTGOING LEG OF THE ADJUSTING SECTION AND PUSHFEEDING THE WEB INTO THE PRINTING SECTION AT SPEEDS CORRESPONDING TO SAID DESIRED WEB PRINTING SPEED, AND (3) DRIVING THE WEB FEED ROLLER TO PULL WEB FROM SAID SUPPLY SECTION AND TO PUSH-FEED IT INTO THE INCOMING LEG OF SAID ADJUSTING SECTION U AT A SPEED NORMALLY APPROXIMATING BUT NOT NORMALLY EQUALING THE WEB PRINTING SPEED OF THE OUTGOING LEG OF SAID U; D. VARIABLE SPEED AUXILIARY DRIVE MEANS TO DRIVE SAID WEB FEED ROLLER AT A SPEED NORMALLY EQUALING THE DIFFERENCE BETWEEN SAID APPROXIMATE SPEED AND SAID WEB PRINTING SPEED AND IN THE CORRECTIVE DIRECTION REQUIRED NORMALLY TO CAUSE THE WEB IN SAID INCOMING LEG TO TRAVEL AT THE SAID WEB PRINTING SPEED OF SAID OUTGOING LEG, AND THEREBY HOLD SAID FLOATING-ROLLER IN A STABLE POSITION; AND E. A CONTROL SYSTEM OPERATIVE, IN RESPONSE TO THE VERTICAL MOTION OF SAID FLOATING-ROLLER OUT OF A STABLE FLOATING POSITION, TO ACTUATE SAID AUXILIARY DRIVE MEANS IN THE DIRECTION REQUIRED TO RESTORE SAID FLOATING-ROLLER TO A STABLE FLOATING POSITION.