Method and apparatus for making air filters

Claim 1

A MACHINE FOR FABRICATING POCKET FILTER UNITS COMPRISING, A FRAME HAVING A TRANSVERSE MEMBER, MEANS ON ONE SIDE OF SAID FRAME FOR SUPPLYING TWO SUPERIMPOSED STRIPS OF FILTER MEDIA FROM SUPPLY ROLLS, TRACTION ROLL MEANS DISPOSED ON THE OTHER SIDE OF SAID FRAME FOR DRAWING SAID SUPERIMPOSED STRIPS OF MEDIA THROUGH THE FRAME, AND OVER SAID TRANSVERSE MEMBER, A PAIR OF VERTICALLY SPACED GUIDE PLATES SUPPORTED FROM AND ABOVE SAID MEMBER THROUGH WHICH THE LOWER STRIP OF MEDIA MAY PASS, A SECOND PAIR OF VERTICALLY SPACED GUIDE PLATES DISPOSED ABOVE SAID FIRST NAMED GUIDE PLATES THROUGH WHICH SAID SECOND STRIP OF FILTER MEDIA MAY PASS, MEANS FOR GRADUALLY AND PERIODICALLY RAISING AND LOWERING SAID SECOND PAIR OF GUIDE PLATES COORDINATED WITH THE DRIVE OF SAID TRACTION ROLLS, WHEREBY TO PERIODICALLY VARY THE SPACING BETWEEN THE SUPERIMPOSED STRIPS OF MEDIA AS THE STRIPS PROGRESS THROUGH THE GUIDE MEANS, AND MEANS OPERATIVELY ASSOCIATED WITH SAID GUIDE PLATES FOR EFFECTING SIMULTANEOUSLY A SERIES OF LATERALLY SPACED ROWS OF STITCHES BETWEEN SAID SUPERIMPOSED STRIPS WHEREBY TO FORM STAYS OF PERIODICALLY VARYING LENGTH BETWEEN SAID STRIPS.