Patent Grant
6923752
1. Field of the Invention
The present invention relates generally to folders for printing presses and more particularly to a folding cylinder for a cross-folder.
2. Background Information
Web printing presses print a continuous web of material, such as paper. In a folder of the printing press, the continuous web then is cut into signatures in a cutting unit and folded. One possible fold to the resulting signatures is a cross-fold perpendicular to the direction of movement of the signatures. A tucking cylinder generally will hold a lead edge of a signature with a pin or gripper, either before or after the signature has been cut from the web. A tucking mechanism in the tucking cylinder may then tuck the signature at a mid-point into a jaw of a jaw cylinder or into folding rolls so as to provide a cross-fold.
U.S. Pat. Nos. 5,102,111 and 5,484,270 for example disclose cross-folding folders having tucking cylinders. A web is received between a cutting cylinder and the tucking cylinder to form signatures, the lead edge of the signatures being held by pins. Tucking blades in the cylinders tuck the signatures into jaws of a jaw cylinder.
U.S. Pat. No. 6,038,974, which is not necessarily prior art to the present invention, discloses a cross folder for receiving signatures in grippers. The folder thus could be used with either a web or sheet-fed printing press. A jaw cylinder and tucking cylinder combination provide the cross-fold.
For cutting webs and tucking and transporting signatures, it is often desirable to vary the outer effective diameter of the tucking cylinder to permit proper processing of variable-thickness signatures. Signature width may vary significantly depending on the desired end product. It thus has been known to provide so-called expansion segments on a tucking cylinder, the expansion segments being adjustable by a cam/spring mechanism to vary the effective outer diameter of the tucking cylinder.
However, it has been found that these expansion segments or their supports can be damaged easily, especially during paper jams on one side of the pin cylinder, for example the work side or the gear side.
An object of the present invention is to provide a folding cylinder with an improved expansion segment.
The present invention provides a folding cylinder comprising:
By being spaced apart from the work-side or gear-side support, space is provided to allow for a non-even depression of the expansion segment in the event of paper jams acting on only one side of the cylinder. Thus, paper jams impacting the expansion segment unevenly need not damage the expansion segment.
The expansion segment preferably includes an outer section and a plurality of J-shaped brackets connected to the outer section. Preferably, a first J-bracket is spaced apart from the work-side support and a second J-bracket is spaced apart from the gear-side support. A third J-bracket may be spaced between the first and second J-brackets.
An end of the J-shaped brackets located opposite the outer section can interact with eccentrics on a camshaft, a rotational angle of the camshaft being adjustable through a worm gear mechanism.
The frame also includes a tie support between the gear-side and work-side supports. Preferably, a plurality of springs on the tie support force the expansion segment radially outwardly. The J-shaped brackets thus may be forced against the eccentrics. By selective rotation of the cam shaft, the effective diameter thus may be set.
Preferably, a space is provided between the expansion segment and the frame both on the gear-side and the work-side. A foam piece preferably is provided in each space, so as to prevent axial movement of the expansion segment except during paper jams. The foam piece most preferably is coated on a frame contact side with a friction-reducing substance, such as TEFLON. The foam piece may be pre-cut to match a profile of a J-bracket and may be pre-applied to the J-bracket by adhesive on an adhesive side opposite the contact side.
The folding cylinder preferably is a pin or pin and tucking cylinder of a cross-folder.
The present invention also provides a method of manufacturing a folding cylinder comprising the steps of:
The method preferably includes placing foam pieces between the expansion segment and the frame.
The terms work-side and gear-side as used herein are for descriptive purposes, and as defined are interchangeable with the terms first and second, respectively.
“Cylinder” as defined herein can be any rotating body.
“Expansion segment” as defined herein is a part of a cylinder which presents itself at an outer section of the cylinder and is adjustable to define an effective diameter of the cylinder.
A preferred embodiment of the present invention is described below by reference to the following drawings, in which:
Cylinder 10 also includes expansion segments 16 spaced between the pins and tucking blades. An outer surface 18 of segments 16 may define an effective diameter of cylinder 10.
Expansion segments 16 are shown in more detail in
Supported in gear-side support 32 and work-side support 36 is a camshaft 40 having eccentrics 41, 42, 43. An end 44 of camshaft 40 may be keyed to a worm drive for setting an angular position of camshaft 40 about its axis.
Eccentrics 41, 42, 43 interact with J-brackets 51, 52, 53 respectively of expansion segment 16. J-brackets 51, 52, 53 are fixedly connected to an outer section 54 of expansion segment 16. On a radially-inward side of outer section 54 are a plurality of springs 61, 62, 63, supported as well by spring support members 37, 38, 39, respectively. It should be understood that more springs may be provided along these spring support members 37, 38, 39 (e.g. into the paper in
Expansion segment 16 thus is forced radially outwardly with respect to frame 30 by the action of springs 61, 62, 63, but is retained by the interaction of J-brackets 51, 52, 53 against eccentrics 41, 42, 43.
The selective rotation of camshaft 40 can change the eccentric angle, so that the eccentrics permit J-brackets 51, 52, 53 and outer section 54 to move radially inwardly or outwardly. An effective outer diameter of cylinder 10 thus may be set.
With the present invention, J-bracket 51 is spaced a distance d1 apart from work-side support 36, and J-bracket 53 is spaced a distance d2 apart from gear-side support 32.
Foam pieces 70, 71 may fit into these spaces to prevent contact between the respective parts. Foam pieces 70, 71 may be pre-cut to match a J-bracket profile and then are applied with pressure-sensitive adhesive to the J-brackets, with a friction-reducing coating being located on the contact surface with supports 36, 32, respectively. However, the foam and any friction-reducing coating may also be pre-applied to a side of the J-brackets, for example through spraying. The friction-reducing coating helps permit adjustment of expansion segment 16 and preferably is made of TEFLON.
The spacing d1, d2 permits segment 16 to slightly move in the event that a paper jam or other obstruction depresses segment 16 unevenly. For example, if a wad of paper or mill splice passes through a pin-jaw cylinder interface only near the work-side support 36, spring 61 compresses, while spring 63 does not. Due to distances d1, d2, the expansion segment 16 can rotate slightly without damage to the expansion segment 16, compressing the upper part of foam piece 70 and the lower end of foam piece 71. Once the obstruction passes, expansion segment 16 can return to its normal position.
The spacings or distances d1 and d2 may be, for example, 2 mm. The foam, which is compressible, helps keep the spacings free of dust, paper and grease.
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