Printing – Rolling contact machines – Rotary
Reexamination Certificate
2001-08-10
2003-11-04
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S494000, C074S573110
Reexamination Certificate
active
06640704
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for balancing rotating bodies, in particular for balancing the drum of a reproduction unit, especially a printing plate exposure device. At least one weight element is repositioned along a predetermined movement path, especially a movement path running at a constant radial distance from the axis of rotation of the rotating body.
The invention further relates to a device for the balancing of rotating bodies, and is particularly applicable to implementing the aforementioned method.
A method of the generic type and a device intended therefor are disclosed in U.S. Pat. No. 5,813,346.
The patent document is concerned in particular with the need to balance the drum of a printing plate exposure device by means of weight elements, before it is set in rotation for the exposure or inscription of the newly mounted printing plate, in order to compensate for imbalances produced by the intrinsic weight of the printing plate and its sometimes incomplete and uneven circumferential distribution. It may also be the case that a plurality of printing plates are fitted to a drum. To solve this problem, the U.S. patent proposes to displace counterweight elements, as necessary, along a predetermined movement path and in this way to redistribute the weight elements. Although for this purpose the weight elements are to be displaceable, it is intended that they be fixable in their respective, selected balancing positions purely by the force of friction.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method and a device for balancing rotating bodies, which overcome the above-mentioned disadvantages of the heretoforeknown devices and methods of this general type and which improve the reliability and security of the weight element fixing while retaining an equally simple facility for the repositioning of the weight elements.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method of balancing a rotating body, which comprises:
providing a rotating body with a given axis of rotation and having a predetermined movement path on the rotating body;
repositioning at least one weight element along the predetermined movement path; and
selectively fixing the weight element in a balancing position by means of interlocking engagement.
Advantageously, the predetermined movement path extends at a constant radial distance from the axis of rotation of the rotating body. The invention is particularly suitable in the context of a roller for a reproduction unit, such as a roller of a printing plate exposure device.
There is also provided, in accordance with the invention, a balancing assembly, comprising:
a rotating body having a defined axis of rotation and formed with a predetermined movement path;
at least one weight element positionable along the predetermined movement path and selectively fixable in a plurality of balancing positions by interlocking engagement with the rotating body.
In other words, the objects of the invention are satisfied by a method and a device in which the weight element (also referred to as a mass element) is fixed in different balancing positions by means of interlocking engagement.
According to the invention, therefore, for fixing the weight element the interlocking engagement is preferred to a frictional engagement. The invention creates the necessary prerequisites for a sufficient number of selectable balancing positions for such a fixing. In practice, two weight elements for each end of the rotating body are generally necessary and sufficient to correct imbalances, since this can by and large compensate for moments occurring due to imbalances, that is to say both untrue running about the axis of rotation and any wobbling movement of the axis of rotation in its bearings.
In order that the weight element may be easily shifted into another position, despite the interlocking engagement of the weight element, it is proposed according to a development of the invention that for onward movement the weight element need only be disengaged from one interlocking engagement and subsequently re-engaged in a new interlocking engagement.
In so doing, engagement occurs, in particular, in a radial direction, and preferably in the direction of the centrifugal force, so that this reinforces the engagement rather than possibly weakening it. In addition the weight element may be loaded, especially spring-loaded, in the direction of engagement.
In accordance with an added feature of the invention, despite the desired interlocking engagement a virtually continuous repositioning of the weight element is possible in each of the balancing positions by providing a bar pattern for the interlocking engagement running along the movement path, the bar pattern gradations of which can be made correspondingly smaller for a larger number of balancing positions. In concrete terms this can be achieved, for example, by means of a bar pattern formed as toothing or knurling.
A device according to the invention for the balancing of rotating bodies of the generic type stated in the introductory part, especially for performing the method according to the invention, is wherein in its independent solution of the stated problem in that the weight element can be fixed in different balancing positions by means of interlocking engagement. This results in the advantages already described in the method according to the invention.
In particular, it is proposed according to developments of The assembly according to the invention that for onward movement along the movement path the weight element should have only to be disengaged from a balancing position and subsequently re-engaged in the new balancing position, especially with the assistance of spring loading, which like the engagement is preferably directed radially and in the direction of the centrifugal force.
In this way the centrifugal force reinforces the interlocking engagement.
In accordance with another development of the invention, the weight element or each weight element be equipped with at least one roller element to reduce friction. This can be achieved directly or indirectly, by supporting a spring element, such as a leaf spring, a leg spring or the like, for example, which exerts a load in the direction of engagement, on rollers or cupped rollers. An (additional) roller bearing in an axial direction can also be an advantage.
In order to permit fixing of the weight element or weight elements that is as unbroken and uniform as possible and virtually continuous along the movement path and thus obtain a finely adjusted and pre-calculable balancing, it is proposed according to the invention that interlocking elements for the weight element preferably form a regular bar pattern running along the movement path. This may be a toothing or a knurling, which can be readily introduced into the material used at a suitable point and over the proposed length using simple tooling. In this way, retrofitting to existing devices is also possible at no major expense. To do this, the measures proposed for realization of the invention can be provided in existing areas or can also be prefabricated, for example, in the area of disk elements or the like that are to be added, that is to say completed altogether as part of a retrofit unit, in principle ready for operation.
Where a toothing is used as interlock pattern for the weight element or weight elements, preferably on an outer rim with toothing directed radially inwards, the interlocking engagement must ensure, solely through the toothing angle and/or the height of the toothing, that the weight element is not also spontaneously displaced again as the rotating body rotates. In this example of an embodiment of the invention, only the said radial guiding and support for the weight element in respect of the interlocking engagement is first necessary.
The movement path is formed in particular by the defining of a bar pattern as guide way for the weight element, an interlocking en
Paasch Burkhard
Siebolds Heinz
Colilla Daniel J.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Mayback Gregory L.
Stemer Werner H.
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