Printing – Rolling contact machines – Rotary
Reexamination Certificate
2003-06-05
2004-09-14
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S219000, C492S030000
Reexamination Certificate
active
06789476
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a rotary body, which is used to compensate the fanout in a printing press or is provided, still outside the printing press, for installation for the purpose of fanout compensation. The printing press is a machine that prints according to the wet method, preferably with the use of a moistening agent. Offset printing shall be mentioned here as an example in particular. The printing press may be a newspaper printing press for printing large newspaper runs. The web is preferably guided as an endless web through the machine and is wound off from a roll, i.e., the printing press is a web-fed printing press and especially preferably a web-fed rotary printing press in such an embodiment.
BACKGROUND OF THE INVENTION
Changes occur in lateral expansion in printing presses because of the liquid having penetrated the web. This phenomenon, known as fanout, has the undesired consequence that the width of the web measured at right angles to the direction of conveying of the web changes between two printing gaps in which the web is printed on one after another. Even though the fanout phenomenon may be caused, in principle, by the ink that alone has penetrated, the fanout is significant in practice especially in the case of printing operating with moistening agent because of the moistening of the web which is associated with it. The web moistened in the upstream printing gap along the web swells on its way and becomes wider in the next printing gap of the two printing gaps, which is located downstream along the web. This leads to printer's errors in the transverse direction of the web unless measures are taken to compensate the change in width.
EP 1 101 721 A1 shows devices for compensating the fanout for the web-fed rotary printing, with which the web is deformed in a wave-shaped pattern at right angles to its direction of conveying before it runs into a next printing gap, in which it is printed on. The width of the web is corrected, i.e., compensated in such a way that it is adapted in advance to the change in width that is to be expected based on the fanout. Since the extent of the change in width that can be attributed to the fanout may change from one run to the next and even within one run when the paper is changed because of different paper grades, EP 1 101 721 A1 also describes, among other things, adjustable fanout compensators, with which the amplitude of the imposed wave shape of the web can be changed in a specific manner. An increase in the amplitude brings about a reduction in the width of the web. The described embodiments of adjustable fanout compensators are formed by a plurality of bodies each, which are arranged along an axis of rotation of the compensator in question alternatingly next to one another and form, corresponding to the desired wave shape of the web, radially projecting head sections and setback foot sections, which are adjustable in relation to one another in order to adapt the extent of the projection and setback of the sections in adaptation to the extent of the change in width that can be attributed to the fanout. However, the prior-art devices, which proved to be successful per se, are complicated and therefore lead to a comparatively high initial cost.
Furthermore, EP 1 101 721 A1 also discloses a fanout compensator that is designed as a rotary body in one piece. This comparatively simple compensator has proved to be successful in practice. However, adaptation to changing run conditions is possible with such a compensator only by keeping ready a plurality of different rotary bodies, which are stored in the printing press in, e.g., a changing frame and can be introduced into or removed from the print run by an adjusting movement of the changing frame.
SUMMARY OF THE INVENTION
The object of the present invention is to also make possible the compensation of a change in the width of a web to be printed on, which change can be attributed to the fanout in adaptation to different run conditions in a simple and inexpensive manner.
The present invention pertains to a rotary body, which is provided for compensating the fanout in a printing press or is already installed in the press in order to guide a web to be printed on, which wraps around the rotary body. The wrapping angle should be at least 3°. However, a wrapping angle of 5° or more, e.g., 10°, is preferred. The wrapping angle may reach up to 180°. The rotary body is intended for being mounted rotatably around an axis of rotation, which extends through the rotary body. Along the axis of rotation, the rotary body forms head sections and foot sections alternatingly next to each other. The surface sections formed by the head and foot sections form the jacket surface of the rotary body. The head sections project over the foot sections radially to the axis of rotation by height differences. Even though the wave contour thus obtained in the axial direction may, in principle, contain jumps, it is preferably continuous. It is especially preferably continuously differentiable and curved in the axial direction, insofar as this can be achieved with the manufacturing methods available in practice at an economically acceptable price. If arc sections with curvatures, which are different, or arc sections with straight axial sections meet, the wave contour may have kinks. Such kinks should be machined such that they have an obtuse angle or are even more preferably round.
According to the present invention, the head and foot sections are not rotatable in relation to one another around the axis of rotation because they are either fitted together and connected to one another in a torsion-proof manner, or they are formed by the rotary body in one piece. Even though examples of such rotary bodies with a wave profile have been known, in principle, from EP 1 101 721 A1, the present invention combines the feature of the torsion-proof connection or, more preferably, the one-piece design with the advantage of adjustability because the radial height differences existing between the head sections and the foot sections increase from minima, which they have along a first straight line offset in parallel to the axis of rotation, to maxima in the circumferential direction around the axis of rotation. The height differences preferably increase monotonically in the circumferential direction. The height differences show the maxima along a second straight line offset in parallel to the axis of rotation. The first straight line and the second straight line are preferably tangents to all head sections, namely, if all head sections have the same radial height in relation to the axis of rotation. If this is not the case, the two straight lines are the tangents to the head section projecting the farthest or to the group of head sections projecting the farthest. A rotary movement around the axis of rotation that is uniform for the entire rotary body is sufficient for the adjustment of the rotary body.
In one preferred embodiment, the height differences assume their maxima along a single straight line. However, it is also possible, in principle, for the maxima to be assumed not only along exactly one straight line, but in an area extending over a certain arc length around the axis of rotation. This may, in principle, also apply in relation to the minima.
The rotary body according to the present invention can be mounted in the printing press in a simple manner and can be mounted rotatably in the same manner as other rotary bodies of the printing press, e.g., deflecting rollers. The assembly of parts that can be adjusted in relation to one another, as in the prior-art, adjustable fanout compensators, is not necessary.
Even though the one-piece design over the entire width of the web is clearly preferred, a fanout compensator is also advantageous that is formed by arranging a few one-piece rotary bodies, e.g., two rotary bodies, next to each other along their common axis of rotation. Compared to a rotary body from individual bodies assembled in a torsion-proof manner, which form a head section o
Colilla Daniel J.
Maschinenfabrik Wifag
McGlew and Tuttle , P.C.
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