Roll or roller – With sheet edge holder – Coating treatment or applicator
Reexamination Certificate
1998-07-09
2001-05-15
Hughes, S. Tom (Department: 3726)
Roll or roller
With sheet edge holder
Coating treatment or applicator
C101S415100, C101S378000
Reexamination Certificate
active
06231490
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device, which is arranged in an axially extending tensioning channel in a cylinder, for fastening a flexible plate around the circumferential surface of the cylinder. The device is particularly for fastening a varnishing or printing plate or a rubber blanket on the periphery of a varnishing or blanket cylinder of a varnishing machine, wherein the plate has start and end edges which and point into the tensioning channel. The leading edge of the plate is held by a leading edge fastening device and the trailing edge is held by a trailing edge fastening device.
German Offenlegungsschrift 40 11 303 discloses a device of this type. The start and the end of a rubber blanket that is tensioned on a cylinder are clamped between a top and bottom rail. In order to tension the rubber blanket, the top and bottom rails are jointly displaced radially inward into the cylinder. The fastening device for the rubber blanket extends over a relatively long distance around the circumference of the cylinder. As a result, a corresponding section of the circumferential surface overall periphery is not available for rolling purposes.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a device of the type mentioned above which has a simple construction, and extends over only a very small distance around the circumference of the cylinder, so that the leading and trailing edges of the plate can be located very closely to each other. This enables virtually the entire circumferential surface of the varnishing cylinder to be used for varnishing purposes. The usable rolling area of the varnishing cylinder surface is thus very large, that is, optimum utilization is achieved by the invention.
According to the invention, this object is achieved by the leading edge fastening device being formed by a start hook-in bar. The leading edge of the plate engages behind that bar. It is further achieved by the trailing edge fastening device being formed by an end hook-in bar, which projects tangentially from a tensioning shaft extending within and parallel to the cylinder. The trailing edge of the plate engages behind that end hook-in bar. The leading and trailing edges are each held without being clamped, but merely by the edges engaging behind the start and end hook-in bars. All that is required for fastening the plate on the cylinder is for the leading and trailing edges to engage behind the start hook-in bar and the end hook-in bar, respectively. The start and end hook-in bars can thus be located opposite each other with just a very small distance between them. It is necessary for that distance to just be sufficiently large, on the one hand, for the plate to be tensioned on the circumferential surface of the cylinder by relative movement of the two bars toward each other, that is, it must be possible to realize an adequate tensioning travel, and, on the other hand, for the leading and/or trailing edge of the plate to have an adequately large entry gap available in order to permit engagement with respect to the respective fastening device during mounting and in order to loosen this engagement during dismounting. Since the plate is held at its start and end edges merely by engagement and not by means which apply a clamping load, there is no additional space requirement for such clamping means as required in the prior art, so that the start and end of the plate lie very closely opposite each other, that is, virtually without a gap. As a result, virtually the entire circumferential surface is available as a rolling area.
In this application, when a configuration of the plate is mentioned, then this is to be understood such that this configuration is not provided directly on the plate but on its profiled end strips. The profiled end strips are viewed virtually as a constituent part of the plate, although they constitute separate components. If, therefore, mention is made, for example, of the fact that a cutout is arranged in the region of the leading edge and/or of the trailing edge of the plate, this likewise means that the cutout can also be located in the region of the leading edge and/or trailing edge of the profiled end strip/profiled end strips.
It is advantageous if the end hook-in bar projects from the tensioning shaft in a tangential direction thereto. In relation to an imaginary radius of the cylinder, the end hook-in bar, viewed in cross section, diverges from this radius. Additionally, that region of the end hook-in bar which engages the trailing edge of the plate is located approximately in the region of the point of intersection of the imaginary radius with the peripheral line of the cylinder. For this purpose, the start hook-in bar, likewise viewed in cross section, which engages the leading edge, preferably diverges from the same radius with the opposite inclination as the end hook-in bar. The two bars are inclined toward each other so as to form only the narrowest possible gap between them, at approximately the level of the outer periphery of the cylinder.
The end hook-in bar is preferably inherently elastic, and specifically is a spring element. As a result of this elastic property, inaccuracies at the ends of the plate which may be caused, for example, by production tolerances, e.g., inaccuracies in parallelism, are compensated for. Since the end hook-in bar is arranged on the tensioning shaft, as mentioned above, that bar may be moved by rotating the tensioning shaft in the direction of the start hook-in bar. This tensions the plate on the periphery of the cylinder. The tensioning shaft has a spring element, preferably in the form of a torsion bar, by which the plate is always subjected to tensile stress, and any rolling effects, and so on, are absorbed. Additionally or alternatively to the construction of the end hook-in bar as a spring element, it is possible for the end hook-in bar to be mounted eccentrically, that is, it can be adjusted in the region of one of its ends, to compensate for any possible inaccuracies in parallelism of the plate. The eccentric bearing is located, as mentioned above, in one end region of the end hook-in bar, whereas its other end region is appropriately pivotally mounted. Since inaccuracies in parallelism and the like can also occur at the start of the plate, the start hook-in bar can also preferably be adapted to the inaccuracies in parallelism, by providing a “movable” start hook-in bar fastening. Preferably, a fastening element, for example a threaded screw, engages through one end region of the start hook-in bar providing a possibility of pivoting the start hook-in bar. In the other end region of the start hook-in bar, there is a possibility of adjustment, in particular by means of a lever mechanism, so that an appropriate oblique setting of the start hook-in bar becomes possible.
The engagement angle of the leading and/or trailing edge is less than 90°, and preferably about 60°, so that there is virtually a form fit in relation to the respective hook-in bar. Even a slight tensioning of the plate thus rules out the possibility of an end of the plate coming loose. On the other hand, the ends of the plate can be lifted from the cylinder without any force being expended when the peripheral tension is loosened, enabling the plate to be changed in an extremely simple and trouble-free manner.
In relation to the construction of the leading edge and/or trailing edge of the plate, the start hook-in bar and/or the end hook-in bar is preferably contoured in its/their respective engagement region such that the parts are caused to contact one another in a form fitting manner over a large area. This provides optimum secureness and reproducibility.
In a particularly simple configuration, the leading edge and/or the trailing edge is/are formed by bent start and end regions of the plate. The bent regions enable the start and end edges of the plate to engage the start hook-in bar and end hook-in bar, respectively so that there is no need for any additional parts for fastening the plate to the cylind
Mokler Bernhard
Speil Werner
Butler Marc W.
Hughes S. Tom
LTG Holding GmbH
Ostrolenk Faber Gerb & Soffen, LLP
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