Apparatus for heat-sealing articles between sheets of transparent material

Claim 1

IN A PACKAGING MACHINE FOR HEAT-SEALING, UPPER AND LOWER CLAMPING ELEMENTS FOR CLAMPING HEAT-SEALABLE MATERIAL ABOUT AN ARTICLE TO BE PACKAGED DURING SEALING, SAID UPPER CLAMPING ELEMENT CONTAINING A CONTINUOUS GROOVE OF RECTANGULAR CONFIGURATION AND MEANS FOR SUPPORTING A HEAT-SEALING RIBBON OF CORRESPONDING SHAPE WITHIN SAID GROOVE, COMPRISING SUPPORTS AT THE FOUR CORNERS OF THE UPPER CLAMPING ELEMENTS HAVING WAYS AT TWO SIDES, YOKES HAVING SPACED PARALLEL ARMS SLIDABLY DISPOSED IN SAID WAYS FOR MOVEMENT ALONG LINES BISECTING THE ANGLES AT THE CORNERS OF THE UPPER SUPPORT, A HORIZONTAL ARM PROJECTING OUTWARDLY FROM EACH YOKE ALONG SAID BISECTING LINE, A PIN FIXED IN THE DISTAL END OF EACH ARM HAVING A LOWER END EXTENDING DOWNWARDLY FROM THE ARM INTO THE GROOVE TO WHICH THE CORNER OF THE RIBBON IS FIXED, SAID SUPPORTS AND YORK CONTAINING ALIGNED OPENINGS, SPRINGS DISPOSED IN SAID OPENINGS AND ADJUSTABLE MEANS ON THE SUPPORTS OPERATIVE TO COMPRESS THE SPRINGS.