Patent Application
20070193463
1. Field of the Invention
The present invention concerns a device and a method for controlling the temperature of a rotating body, i.e., especially for controlling the temperature of a cylinder, e.g., a blanket cylinder of a printing press.
2. Description of the Related Art
In printing presses, the rolling of two cylinders on each other can cause local heating. For example, this can be the case with a blanket cylinder that is fitted with a rubber blanket or rubber sleeve and is rolling on a plate cylinder. The local heat input occurs especially in the area of contact of the blanket cylinder with the channel of the plate cylinder. The phenomenon of local heat input is referred to as the hot spot problem, which can also arise with blank cylinder/blanket cylinder printing units in the area of contact between the blanket cylinders.
The local heat input results in unbalanced linear expansion of the cylinder and thus to curvature of the cylinder, especially when the ratio of length to diameter is large. The curvature of the cylinder in turn leads to eccentric running during the rolling of the cylinder and thus to reduced printing quality in the production process of the printing press.
Based on the above statement of the problem, the objective of the invention is to create a device or a method that counteracts reduced printing quality due to the development of hot spots.
In accordance with the invention, a rotating body, such as a cylinder and especially a blanket cylinder, is produced for a printing press, wherein the rotating body has at least one opening. The opening can be, for example, a bore subsequently produced in the cylinder. The bore is provided essentially in the axial direction of the rotating body and preferably coaxially within the rotating body. The purpose of the bore is to introduce a fluid into the rotating body and then remove it from the rotating body in order to control the temperature of the rotating body.
Since the development of a hot spot on the surface of a cylinder causes unbalanced heating of the cylinder, bending of the cylinder occurs, especially when the cylinder is long relative to its diameter. Unbalanced heat input does not occur if the temperature difference due to the hot spot is reduced or completely compensated. The bore that is provided makes it possible, in a way that is practicable and favorable from the standpoint of production engineering, to provide the cylinder with a mechanism for controlling its temperature. The use of a single bore for introducing and removing a fluid for controlling the temperature of the cylinder is a solution which is favorable from the standpoint of production engineering and allows the cylinder to be heated to a temperature that is not susceptible to curvature due to the development of hot spots on the surface of the cylinder.
In accordance with a refinement of the invention, a supply line with at least one inlet is provided in the bore inside the rotating body. The temperature-control fluid flows into the rotating body through the supply line, and the fluid flows out of the inlet that is provided and back out of the rotating body through the space between the bore and the supply line, i.e., along the inside surface of the bore.
In accordance with a first embodiment according to the invention, the bore in the rotating body or cylinder can pass completely through the rotating body. In this case, one end of the bore must then be closed with a suitable closure. As an alternative, the bore can be realized in such a way that it does not pass completely through the rotating body, i.e., the bore depth adapted to the cylinder provides for the closure at the second end of the cylinder.
This design makes it possible to provide both a supply line and a discharge line through a connector on one end face of the rotating body, i.e., in the case of a blanket cylinder, on the base of the blanket cylinder. The connector itself does not rotate, and the rotating body is rotatably supported on the connector. Fluid that has been adjusted to a desired temperature in a temperature-control system enters the rotating body through the connector.
In accordance with the first embodiment of the invention, at least one spacer can be provided between the supply line and the inner wall of the bore. The supply line can be supported on this spacer, but it is also possible for the supply line to be rotatably supported in the connector, so that it becomes unnecessary to provide spacers, or the manufacturing precision of the spacers can be lower. To allow a suitable amount of backflow of the fluid in the bore, the spacers can be additionally provided with flow-through zones, i.e., openings in the spacer.
In accordance with another embodiment of the invention, a different design can be chosen, so that the use of a supply line is merely optional. Specifically, if the bore passes completely through the rotating body, it becomes possible to introduce the fluid at one end of the rotating body and to discharge it again at the other end of the rotating body. This makes it necessary to provide two connectors, i.e., one at each end of the rotating body, which again allow relative movement between the rotating body and connectors.
In accordance with a modification of the invention, which is possible both for the design with the inlet and outlet at one end and for the design with the inlet at one end and the outlet at the other end, the surface of the inner wall of the bore is increased to improve the heat transfer to the rotating body. A baffle can be provided in the bore as this device for increasing the surface area, which divides the fluid into numerous separate streams, which then flow over the enlarged surface of the baffle. Moreover, it is also possible to reduce the flow rate of a fluid to extend the time available for transferring heat to the rotating body. The device for increasing the surface area or reducing the flow rate can be contrived either as a special baffle or as an alteration of the surface features of the bore carried out as a machining operation on the bore.
In accordance with another modification of the invention, a temperature-control system can be provided in the immediate proximity of the rotating body in addition to or instead of the temperature-control system customarily used in printing presses. The use of a temperature-control system in the vicinity of the rotating body makes it possible to reduce the delay time for heating the rotating body. The additional temperature-control system can be connected, for example, to a line of the printing press temperature-control system that runs to the rotating body to be heated. The additional temperature-control system can be, for example, an electric heat exchanger, which can be designed, for example, as a flow heater. Furthermore, it is possible to mount this flow heater parallel to the supply line of the printing press temperature-control system that runs to the rotating body, so that operation with or without the flow heater is possible.
In addition, the objective of the invention can be achieved by a method of the invention for controlling the temperature of a rotating body of a printing press. The printing press has rotating bodies that roll on one another and a temperature-control system for heating at least one rotating body. As described earlier, the rolling of the rotating bodies on each other generates heat on the surface of the heatable rotating body and as a result, in the most unfavorable case, only a portion of the surface of the heatable rotating body is heated to a first temperature. In accordance with the invention, the step of the method in which the rotating body is heated compensates unbalanced heat input on the surface, i.e., the development of hot spots.
In accordance with an advantageous modification of the invention, the temperature produced in the rotating body by the temperature-control system must be at least as high as the temperature on the surface of the rotating body. The rotating body is preferably already heated up before the start of printing or before other parts of the printing press are started up.
It is advantageous for the device of the invention to be based on a conventional cylinder design. In other words, since a bore can be made in a conventional cylinder, a multipart cylinder is not necessary, but rather a conventional cylinder can also be reshaped in connection with a retrofitting.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.
The connector 5 is preferably a rotationing union of the type sold by the Deublin Company of Waukegan, Ill. For the embodiment of
Since the bore 2 passes completely through the blanket cylinder 1 in the illustrated embodiment, a closure 8 for closing one end of the bore is provided on the base of the blanket cylinder at the opposite end of the cylinder from the connector 5. In the vicinity of the temperature-control line 12, an additional temperature-control system 9 is provided parallel to the temperature-control line 12. The fluid supplied to the blanket cylinder can be heated more quickly via the bypass through the additional temperature-control system 9 by a suitable valve mechanism (not shown) in order to reduce the delay time during the heating of the blanket cylinder.
To heat the blanket cylinder, a heated fluid flows into the supply line 3 through the temperature-control line 12 and the connector 5. The supply line 3 has at least one inlet, preferably at the end of the supply line. In addition, a plurality of openings can be provided in the circumferential direction of the supply line. The temperature-control fluid flows back to the connector 5 in the space between the supply line 3 and the bore 2, and is removed from the connector 5 through a discharge line 13. Alternatively, the pipeline designed as a supply line in this embodiment could also be used as the discharge line, so that the direction of flow would be just the opposite of that described in connection with the embodiment illustrated here. Furthermore, it is also possible to dispense entirely with a supply line and to carry out the operation of flooding the bore 2 by means of the pressure of the entering fluid.
Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 005 151.3 | Feb 2006 | DE | national |
