Claims
- 1. Means for interrupting the feeding of sheets to a sheet-fed printing press comprising, in combination, a press drive, a feed table, means defining a registered position of a sheet thereon, means coupled to the drive for feeding sheets across the feed table in succession into engagement with the registering means, a gripper cylinder, said gripper cylinder being coupled to the drive for picking up successive sheets following register intervals, retaining means having a retaining foot spaced opposite a sheet on the feed table and having provision for energization to press the foot downwardly against the sheet to immobilize the sheet so that it is not picked up by the cylinder, means for detecting failure of register of a sheet during a register interval for energizing the retaining means, time delay means interposed between the detecting means and the sheet retaining means to delay operation of the retaining means thereby to insure that the preceding sheet picked up by the gripper cylinder is clear of the feed table so that the foot presses downwardly upon the non-registered sheet, and means for permitting manual removal of the non-registered sheet from below the foot.
- 2. The combination as claimed in claim 1 in which the retaining means includes a shiftable member for mounting the foot and in which a resilient biasing spring is provided for biasing the foot in the direction of the table, the yielding of the biasing spring in the face of upwardly applied manual force permitting a non-registered sheet to be manually withdrawn from under the foot while the retaining means is in its energized condition.
- 3. The combination as claimed in claim 2 in which the retaining means includes a spring-returned pneumatic cylinder operated by the detecting means for overcoming the biasing spring to raise the foot from the table.
- 4. The combination as claimed in claim 1 in which the retaining means includes a pneumatic cylinder for controlling the position of the foot, the cylinder having a magnetic control valve energized by the detecting means.
- 5. The combination as claimed in claim 1 in which the retaining means includes an electromagnet for actuating the foot between extended and retracted positions, the electromagnet being energized by the detecting means.
- 6. The combination as claimed in claim 1 in which the retaining foot is in the form of a pivoted cam, the cam having a pivot axis parallel to the table and having a foot in the form of an eccentric surface presented adjacent the table, means energized by the detector means for rocking the cam to rotate the eccentric surface into contact with a sheet to retain the same, the cam and its rocking means having a resilient return spring connected thereto in opposition to the rocking means to facilitate manual withdrawal of a non-registered sheet from under the foot while the retaining means is in its energized condition.
- 7. The combination as claimed in claim 1 in which means are provided for maintaining the retaining means latched on until the sheet has been removed.
- 8. The combination as claimed in claim 1 in which the detecting means includes detectors mounted at a registered edge of the sheet to indicate the absence of register, and means synchronized with the press drive for enabling the detectors only during a register interval while disabling the detectors at all other times.
- 9. The combination as claimed in claim 1 in which the detecting means includes photocells mounted at a registered edge of the sheet, the output circuit of the photocells being arranged to produce an output signal in the absence of register, means interposed between the photocell output circuit and the retaining means and synchronized with the press drive for enabling the retaining means to be energized in response to the photocell output signal only during the register interval, and means for maintaining the retaining means latched in the energized state until the non-registered sheet is removed.
- 10. Means for interrupting the feeding of sheets to a sheet-fed printing press comprising, in combination, a press drive, a feed table, means including stops defining a registered position of a sheet on the table, means coupled to the drive for feeding sheets across the table in succession into engagement with the stops to define a register interval during which register takes place, a gripper cylinder, said gripper cylinder being coupled to the drive for picking up successive sheets following the register interval, retaining means having a retaining foot spaced opposite a sheet on the feed table and having provision for energization to press the foot downwardly against the sheet to immobilize the sheet so that it is not picked up by the cylinder, photocells mounted on the table at the edge of the sheet for detecting failure of a sheet to move into registered position, the output circuit of the photocells being arranged to produce an output signal in the absence of register, an enabling switch coupled to the press drive and closed during the register interval for causing the retaining means to be energized in response to the photocell output signal only during the register interval, time delay means responsive to the photocell output signal to delay operation of the retaining means thereby to insure that the preceding sheet picked up by the gripper cylinder is clear of the feed table so that the foot presses downwardly upon the non-registered sheet, means for latching the foot in its downwardly pressed condition for temporarily retaining the sheet, and means permitting manual removal of the non-registered sheet from below the foot to enable resumption of the flow of sheets into registered position.
- 11. The combination as claimed in claim 1 in which means are provided responsive to operation of the detecting means for disabling the press.
- 12. The combination as claimed in claim 1 in which the retaining means includes a pivoted member with the pivot being horizontal and transversely arranged with respect to the direction of normal travel of the sheet, the foot of the retaining means being mounted upstream of the pivot so that manual retraction of the sheet during continued energization, and using light manual force, is only possible in a direction opposite to the direction of normal travel and so that a non-registered sheet is, during removal, retracted from the region of pickup.
- 13. The combination as claimed in claim 1 in which the foot includes means for imparting a wiping action to the sheet as the foot engages the sheet for wiping the sheet backwardly with respect to the direction of normal travel so that a non-registered sheet is retracted from the region of pickup.
- 14. Means for interrupting the feeding of sheets to a sheet-fed printing press comprising, in combination, a press drive, a feed table, means including stops defining a registered position of a sheet on the table, means coupled to the drive for feeding sheets across the table in succession into engagement with the stops to define a register interval during which register takes place, a gripper cylinder, said gripper cylinder being coupled to the drive for picking up successive sheets following the register interval, retaining means having a retaining foot spaced opposite a sheet on the feed table and having provision for energization to press the foot downwardly against the sheet to immobilize the sheet so that it is not picked up by the cylinder, photocells mounted on the table at the edge of the sheet for detecting failure of a sheet to move into registered position, the output circuit of the photocells being arranged to produce an output signal in the absence of register, enabling means coupled to the press drive and closed during the register interval for causing the retaining means to be energized in response to the photocell output signal only during the register interval, means responsive to the photocell output signal to insure that the preceding sheet picked up by the gripper cylinder is clear of the feed table so that the foot presses downwardly upon the non-registered sheet, means for latching the foot in its downwardly pressed condition for temporarily retaining the sheet, the pressure exerted by the foot being such as to permit manual removal of the non-registered sheet from below the foot by retraction in the upstream direction, and means responsive to the manual retraction of the sheet for releasing the latching means to disengage the foot for resumption of the flow of sheets into registered position.
Parent Case Info
This application is a continuation-in-part of our application Ser. No. 570,265 filed Apr. 21, 1975, now abandoned, entitled Sheet Lock.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
2072235 |
Wormser |
Mar 1937 |
|
2708405 |
Gegenheimer |
May 1955 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
667,829 |
Oct 1938 |
DD |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
570265 |
Apr 1975 |
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