Patent Grant
6843763
The present invention relates generally to printing presses and more particularly to a folder of a printing press.
Web printing press print a continuous web of material, such as paper. In a folder of the web printing press, the continuous web then is cut into signatures in a cutting unit and folded.
U.S. Pat. No. 5,429,578 describes a jaw folder receiving a web of material. A cutting cylinder, transfer cylinder and jaw cylinder are provided. The web is cut by the transfer cylinder where the lead edge of the signature is secured by pins. The signature is thus held on the transfer cylinder until tucking blades on the transfer cylinder tuck the signatures into jaws of the jaw cylinder. Thus a cross-fold on the signatures is created along a fold line perpendicular to the travel direction of the signatures. The signatures are then held by the jaws at the fold line until the signatures are to be released. In order to change the position of the fold with respect to the lead edge, the position of the tucking blade with respect to the pins is changed.
The signature 5 is supported by cantilevered support segments 18 and 19 attached to spider 12 and supports 21 attached to spider 14. However, in order to provide for relative adjustment of spider 12 with respect to spider 14, gaps 8 and 9 are provided between the cantilevered segments. These gaps 8, 9 have respective clearances d, e which define the amount of relative adjustment possible between the spiders 12, 14.
If large cross-fold adjustment is desired, the gaps in the transfer cylinder must be rather large, which can lead to a lack of support for signatures that in turn can lead to defects such as creasing, edge-tearing or dog-earring. The cantilevered support segments also may be prone to damage from jam forces, which can cause them to bend or break off.
Particularly in the field of newspaper presses, it has been known to provide rotary blade folders, also known as drum folders, that tuck a thick newspaper signature into two nip rollers. U.S. Pat. No. 5,122,109 discloses such a rotary blade folder. The rotary blade passes through bands at the outer surface of the cylinder. Pins for the lead edge of the signature pass through an axially extending gap of the cylinder. In newspaper rotary blade folders of this type it is desirable to adjust the effective radius of the bands to accommodate different signature thicknesses, and thus the bands are located at the tucking blades.
Commonly-assigned U.S. Ser. No. 09/571,606 (which is not necessarily prior art to the present invention) describes a rotary blade folder with an expansion plate with apertures that permit the rotary blades to pass therethrough, and permits adjustment of the effective diameter of the cylinder. The pins remain exposed. The newspaper rotary blade folders do not interact with a jaw cylinder.
Also, in rotary blade or drum folders, the tucking blades typically are supported on an interior cylinder with a planetary gear and then pass through bands, so that the gap problem mentioned with respect to jaw folders often does not exist.
An object of the present invention is to provide a folding cylinder with improved support for signatures. An additional or alternative object of the present invention is to provide a jaw folder with improved support for signatures.
The present invention provides a folding cylinder comprising a plurality of gripping devices for a lead edge of a signature, the gripping devices being supported on a first rotatable support and including a first gripping device. A plurality of tucking devices are supported on a second rotatable support, the tucking devices including a first tucking device and a second tucking device, the first gripping device being located circumferentially between the first tucking device and second tucking device. A cover is fixed to the second rotatable support and extends circumferentially over the first gripping device between the first tucking device and the second tucking device, the cover having at least one aperture, with the first gripping device capable of extending through the at least one aperture.
By having a cover extend over the gripping devices between the first tucking device and the second tucking device, gaps, and the resultant defects such as dog-earring and creasing, can be eliminated.
Preferably, the at least one aperture includes a plurality of apertures spaced axially next to each other, and the first gripping device includes a plurality of axially spaced grippers. Alternately, the first gripping device may include a plurality of axially spaced impaling pins. “Gripping device” as defined herein is any device for holding the edge of a signature on a cylinder and includes both grippers and pins.
Preferably, the first and second support are rotatable with respect to each other and have a common axis of rotation.
The second support preferably is a spider having a first spider arm supporting the first tucking device and a second spider arm supporting the second tucking device, the cover being fixed at one end to the first spider arm and at another end to the second spider arm.
Additional covers having apertures are preferably provided along the entire circumferential extent of the cylinder.
The present invention also provides a jaw folder comprising a cutting cylinder for cutting a signature from a web and a transfer cylinder including a plurality of gripping devices for holding a lead edge of the signature. The gripping devices are supported on a first rotatable support and include a first gripping device. The transfer cylinder includes a plurality of tucking devices supported on a second rotatable support, the tucking devices including a first tucking device and a second tucking device, the first gripping device being located circumferentially between the first tucking device and second tucking device. The transfer cylinder also includes a cover fixed to the second rotatable support and extending circumferentially over the first gripping device between the first tucking device and the second tucking device, the cover having at least one aperture, the first gripping device capable of extending through the at least one aperture. A jaw cylinder receives the signature at a fold created by the first tucking device.
The jaw folder of the present invention can reduce folding defects.
The present invention also provides a method of folding a signature comprising the steps of:
moving a gripping device through an aperture of a cover on a folding cylinder, the cover extending over the gripping device when the gripping device is retracted;
gripping the signature and supporting signature on the cover as the folding cylinder rotates; and
tucking the signature using a folding blade.
Preferably, the signature is tucked into the jaw of a jaw cylinder.
Embodiments of the present invention is described below by reference to the following
Covers 60 extend over the pins 50, and are fastened by a fastener 62, for example screws, at one end to one arm of tucker spider 146 and at the other end by a fastener 64. The covers 60 have apertures through which the pins 50 can extend. While covers 60 are fixed to spider 146, spider 150 can rotate with respect to covers 60, and thus the apertures preferably are elongated in the circumferential direction so that the pins 50 can extend through the apertures even as the fold location changes.
Extending between two arms 72 of spider 70 are two curved supports 78 (one of which is shown in
Each cover 92 has a plurality of axially-spaced apertures or holes 94, that preferably are elongated in the circumferential direction, i.e. that their axial width is smaller than their circumferential length.
Gripper spider 80 has arms 82 supporting gripping devices 84. Each gripping device has a plurality of axially-spaced grippers 86 which can extend through the apertures 94 to hold a lead edge of a signature.
The distance between the gripping device 84 and tucking device 74 determines the cross-fold location for the signature. This distance can be altered by changing the phase angle between the gripper spider 80 and the tucker spider 70. The grippers 86 thus are rotated with respect to the tucking blade 76. Since the apertures 94 are elongated in the circumferential direction, the grippers 86 have a wide range of available motion with respect to the tucking blades 76 so as to set the fold location.
Cover 60 of the
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| Number | Date | Country | |
|---|---|---|---|
| 20030110968 A1 | Jun 2003 | US |
