Uniform pressure draw rolls

Claim 2

In a web handling machine a draw roll assembly for gripping the web comprising an upright frame plate at each side of the machine, a transverse bridge beam spanning said frame plates, a lower roll rotatably mounted between said frame plates, an upper roll displaceably mounted for downward engagement with said lower roll, a fluid operated cylinder mounted on said bridge for applying downward bias to each end portion of said upper roll, an intermediate fluid operated cylinder mounted on said bridge for applying a downward bias on said upper roll, a bracket depending from said bridge, and a presser arm pivoted to said bracket and extending under the piston rod of said intermediate cylinder above the path of the web, said presser arm having an arcuate undersurface engaged with a complementary upper surface of said upper roll to apply downward bias thereto without interference with the web.

Claim 3

Apparatus according to claim 1, and a fixed support yoke in supporting engagement with said lower gripping roll in opposition to said presser arm.

Claim 4

Apparatus according to claim 2, and a central annular bearing intermediate the ends of said lower roll, said fixed support yoke having an arcuate support surface engaged with said bearing but terminatIng below the path of the web, a second annular bearing intermediate the ends of said upper roll and defining said complementary upper surface engaged by the free end of said presser arm, said upper and lower rolls each comprising two coaxial sections separable in the plane of its associated bearing, one of said sections having a projecting, stepped shaft engaged with the bearing and keyed into a bore of the adjacent section.

Claim 5

Apparatus according to claim 3, and a pivot arm connected to each end of said upper gripping roll, means pivoting each arm to the adjacent one of said frame plates, a mounting bar interconnecting said frame side plates beneath the path of the web and intermediate the ends of said pivot arms, and a compression spring mounted between each pivot arm and said mounting bar, said springs applying upward bias to said upper roll for releasing gripping pressure and lifting said upper roll when all three of said pressure cylinders are deenergized.

Claim 6

In a web handling machine a draw roll assembly for gripping the web comprising an upright frame plate at each side of the machine, a transverse bridge beam spanning said frame plates, a lower roll rotatably mounted between said frame plates, an upper roll movably mounted for downward engagement with said lower roll, fluid operated cylinders mounted on said bridge for applying downward bias to each end portion of said upper roll, and an intermediate fluid operated cylinder mounted on said bridge for applying a downward bias on the mid-portion of said upper roll; the improvement comprising a bracket depending from said bridge, a movable presser arm, means for movably supporting said presser arm on said bracket with said arm extending under the piston rod of said intermediate cylinder above the path of the web, said presser arm having an undersurface engaged with a complementary upper surface of said upper roll to apply downward bias thereto without interference with the web, and means for causing said central cylinder to apply proportionately more force than said end cylinders in order to maintain the linearity of said movable roll and produce a uniform gripping force along the nip of said fixed and movable rolls.

Claim 7

In a web handling machine a draw roll assembly for gripping the web comprising an upright frame plate at each side of the machine, a transverse bridge beam spanning said frame plates, a lower roll rotatably mounted between said frame plates, an upper roll movably mounted for downward engagement with said lower roll, fluid operated cylinders mounted on said bridge for applying downward bias to each end portion of said upper roll, and an intermediate fluid operated cylinder mounted on said bridge for applying a downward bias on the mid-portion of said upper roll; the improvement comprising a bracket depending from said bridge, a movable presser arm, means for movably supporting said presser arm on said bracket with said arm extending under the piston rod of said intermediate cylinder above the path of the web, said presser arm having an undersurface engaged with a complementary upper surface of said upper roll to apply downward bias thereto without interference with the web, and means for causing said central cylinder to apply proportionately more force than said end cylinders in order to maintain the linearity of said movable roll and produce a uniform gripping force along the nip of said fixed and movable rolls.

Claim 8

The machine of claim 5 wherein said presser arm is pivotally mounted on said bracket.

Claim 9

The machine of claim 6 wherein said bracket is a flat, platelike member.