Sheet feeding device

Claim 2

An automatic sheet feeding device, particularly for feeding thin metal sheets to a machine having a table, comprising two vertical columns spaced from one another on a line extending transversely of said table, a sleeve vertically slidable on each of said columns, a crosspiece extending between and connecting said sleeves, a sheet feeding unit carried by said unit comprising a horizontal plate having a smooth upper surface, spaced parallel shafts above said plate, pulleys on said shafts and a belt running on said pulleys and having a lower run extending along said upper surface of said plate, said belt having a higher coefficient of friction than said plate, means for driving one of said pulleys, means for delivering a single sheet between said plate and said belt to be transported across said plate by said belt and means for moving said sleeves, crosspiece and feeding unit vertically on said columns to bring said plate to a level to feed said sheet from between said plate and belt onto said table.

Claim 3

A sheet feeding device according to claim 1, in which said means for driving one of said pulleys comprises a power driven drive sprocket, disposed below said sheet feeding unit, an idler sprocket disposed above said unit, a driven sprocket on the shaft of said pulley, a chain running on said drive sprocket, idler sprocket and driven sprocket and guide rollers carried by said unit and guiding said chain to said driven sprocket in all positions of said unit.

Claim 4

A sheet feeding device according to claim 1, in which said unit comprises a horizontal beam carried by said crosspiece and having forked ends supported by said shafts.

Claim 5

A sheet feeding device according to claim 3, in which spring pressed rollers carried by said beam engage the lower run of said belt to press it toward said plate and a spring biased idler roller carried by said beam engages the upper rum of said belt to tension said belt.

Claim 6

A sheet feeding device according to claim 1, in which said means for moving said feed unit vertically comprises a pneumatic cylinder and piston acting between said cross bar and a stationary support, and means for supplying fluid under pressure to said cylinder.

Claim 7

A sheet feeding device according to claim 5, comprising an electromagnetically releasable safety catch for preventing downward movement of said unit if power is off.

Claim 8

A sheet feeding device according to claim 1, comprising control means actuated by movement of said sheet by said belt for stopping said belt and initiating downward movement of said unit when said sheet has moved to a selected position.

Claim 9

A sheet feeding device according to claim 7, comprising control means actuated by movement of said unit to restart said belt when said unit has moved down to a selected position.

Claim 10

A sheet feeding device according to claim 1, in which said sheet delivering means comprises an articulated quadrilateral mechanism, depending sucker arms carried by said mechanism, suckers on said arms and means for actuating said mechanism to move said arms vertically and angularly to pick up a sheet from a pile of sheets and deliver it to said feeding unit.

Claim 11

A sheet feeding device according to claim 9, in which said actuating means comprises a bell crank lever one arm of which is a member of said quadrilateral mechanism, a roller carried by said one arm, a guide plate engaged by said roller and a cylinder having a piston rod engaging the other arm of said bell crank lever.

Claim 12

A sheet feeding device according to claim 10, in which said quadrilateral mechanism comprises a first arm pivotally mounted intermediate its ends, a transverse shaft at one end of said first arm, said shaft carrying said sucker arms, a second arm fixed to said shaft, said one arm of said bell crank lever and a draw bar of variable length connecting said second arm with said one bellcrank lever arm.

Claim 13

A sheet feeding device according to claim 9, comprising means for sensing the level of the top of said pile of sheets comprising a feeler carried by said quadrilateral mechanism and engageable with the top of said pile and a microswitch actuatable by said quadrilateral mechanism.

Claim 14

A sheet feeding device according to claim 12, comprising means for sensing the exhaustion of the sheets of said pile, said pile being supported on a nonconductive conductive support, said sensing means comprising means engaging the top sheet of said pile and responsive to the conduction of said metal sheets.

Claim 15

A sheet feeding device according to claim 1, comprising means for positioning a sheet on said table, said positioning means comprising abutments for two edges of said sheet, pressure fluid operable means for moving said sheet into engagement with said abutments and microswitches for controlling said pressure fluid operable means.

Claim 16

A sheet feeding device according to claim 1, comprising means for sensing a double sheet delivered by said delivery means and means controlled by said sensing means for deflecting said double sheet away from said feeding unit.

Claim 17

A sheet feeding device according to claim 1, in which said belt has a forward end portion supported by one said pulley ahead of said plate, and in which a guide roller is positioned under said one pulley, said sheet delivered by said sheet delivering means passing between said guide roller and said pulley.

Claim 18

A sheet feeding device according to claim 16, comprising means for sensing a double sheet delivered by said sheet delivering means and means controlled by said sensing means for deflecting said double sheet, said deflecting means being between said guide roller and said plate.

Claim 19

A sheet feeding device according to claim 1, in which said sheet feeding unit comprises two side members one of which is fixed to said crosspiece and the other of which is movable along said crosspiece to vary the distance between said side members, said shafts extending between said side members.

Claim 20

An automatic sheet feeding device, comprising a conveyor arrangement and means for feeding a sheet to the conveyor arrangement, the feeding means including an arm, at least one sucker mounted on the arm for engaging a surface of a sheet to be fed, and a linkage including four articulated members arranged in the form of a quadrilateral, the linkage including a first member pivotally mounted between its ends, a second member pivotally connected adjacent one end of the first member, the second member forming part of a lever, a roller pivotally connected at one end of the second member, a third member pivotally connected by one end to the opposite end of the roller, and a fourth member pivotally connected to the opposite end of the third member and pivotally connected to the opposite end of the first member, said arm being connected to the fourth member for movement therewith, a stop positioned to engage the roller when the linkage occupies a first inoperative position, resilient means for biasing the linkage towards said first inoperative position, and means for exerting a force on the linkage to move the linkage between the first inoperative position and a second delivery position, said force exerting means being arranged to engage a surface of the lever whereby the first member is caused initially to pivot, so that the arm is lifted, subsequent pivotal movement of the first member causing the roller to clear the stop and permit pivotal movement of the second member and consequently the relative pivotal movement of the linkage to cause the linkage to move to the second delivery position at which position the sucker is adjacent an entrance zone of the conveyor arrangement.

Claim 21

An automatic sheet feeding device, comprising a conveyor arrangement and means for feeding a sheet to the conveyor arrangement, the feeding means including an arm, at least one sucker mounted on the arm for engaging a surface of a sheet to be fed, and a linkage including four articulated members arranged in the form of a quadrilateral, the linkage including a first member pivotally mounted between its ends, a second member pivotally connected adjacent one end of the first member, the second member forming part of a lever, a roller pivotally connected at one end of the second member, a third member pivotally connected by one end to the opposite end of the roller, and a fourth member pivotally connected to the opposite end of the third member and pivotally connected to the opposite end of the first member, said arm being connected to the fourth member for movement therewith, a stop positioned to engage the roller when the linkage occupies a first inoperative position, resilient means for biasing the linkage towards said first inoperative position, and means for exerting a force on the linkage to move the linkage between the first inoperative position and a second delivery position, said force exerting means being arranged to engage a surface of the lever whereby the first member is caused initially to pivot, so that the arm is lifted, subsequent pivotal movement of the first member causing the roller to clear the stop and permit pivotal movement of the second member and consequently the relative pivotal movement of the linkage to cause the linkage to move to the second delivery position at which position the sucker is adjacent an entrance zone of the conveyor arrangement.