SUOMI EERO (FI)
| DE19812149A1 | 1999-09-23 |
| 1. | A device for dividing local thermal loads equally in a rotating, liquidcontaining roll (1) of a paper/board or finishing/converting machine, characterised in that the device comprises a fixed support (2) extending from at least one end of the roll (1) inside the roll (1), coaxially with the axis of rotation of the roll (1), from which support is arranged to protrude one or more mixing means (3). |
| 2. | A device as claimed in claim 1, characterised in that the fixed support (2) is arranged to extend over the entire length of the roll (1). |
| 3. | A device as claimed in claim 1, characterised in that the mixing means (3) is arranged in a fixed position with respect to the fixed support (2). |
| 4. | A device as claimed in claim 1, characterised in that the position of the mixing means (3) is arranged to be adjustable with respect to the fixed support (2). |
| 5. | A device as claimed in claim 1, characterised in that the location of the mixing means (3) is arranged to be adjustable with respect to the fixed support (2). |
| 6. | A device as claimed in claim 1, characterised in that the mixing means (3) is equipped with adjustment means which make possible adjustment of the mixing means during rotation of the roll (1). |
| 7. | A method for dividing local thermal loads equally in a rotating, liquid containing roll (1) of a paper/board or finishing/converting machine, characterised in that the flow of the liquid inside the rotating roll (1), which thus rotates with the roll, is controlled by means of one or more mixing means (3), which are stationary inside the roll (1). |
In the prior art is known a solution in which water is used inside a rotating roll for dividing local thermal loads equally. The water is circulated by means of a separate external pump, or the water is enclosed inside the roll without circulation.
The aim in dividing the heat equally is to eliminate an increase in the diameter of the middle part of the roll, which is due to an uneven thermal load and occurs particularly in polymer rolls. The said increase in diameter results in a decrease in edge load. This in turn creates a so-called weeping gloss profile in the paper.
Known solutions concerning the equal dividing of heat have not been entirely satisfactory in all cases.
The aim of the invention is to provide a simple, efficient, reliable and economical method and device for dividing thermal loads equally.
This aim has been achieved by means of the device and method disclosed in the claims.
It is characteristic of the device relating to the invention that the device comprises a fixed support extending from at least one end of the roll inside the roll, coaxially with the axis of rotation of the roll, from which support is arranged to protrude one or more mixing means.
It is characteristic of the method relating to the invention that the flow of the liquid inside the rotating roll, which thus rotates with the roll, is controlled by means of one or more mixing means, which are stationary inside the roll.
The mixing effect of the liquid is created by the interaction between the stationary mixing means and the liquid rotating with the rotating roll. The mixing effect in turn divides local thermal loads equally. The surface area and the angle of incidence of the mixing means are factors affecting internal flow and the effect of heat transfer. The set power adjustments of the mixing means may be changeable during operation or they may be set fixed.
Further preferable developments of the invention are disclosed in the dependent claims.
The invention is described in greater detail in the following, with reference to the accompanying drawing, which shows diagrammatically a liquid-filled rotating roll provided with the device relating to the invention for dividing thermal loads equally.
In the drawing, the rotating (arrow 6) liquid-filled roll of the paper/board or finishing/converting machine is marked generally with reference numeral 1. The roll 1 comprises a mantle surface 4 and end flanges 5. To fit the roll 1 with bearings, the end flanges 5 are provided with bearings (not shown) known as such, on which the roll 1 rotates.
The device for dividing thermal loads equally comprises a fixed support 2 extending from at least one end of the roll 1 inside the roll 1, coaxially with the axis of rotation of the roll 1, from which support is arranged to protrude one or more mixing means 3.
The fixed support 2 may be arranged to extend over the entire length of the roll 1, as in the example shown in the drawing, or the fixed support 2 may be shorter and extend only over a part of the length of the roll 1, starting from one or both of the flanges 5.
The mixing means 3 can be arranged in a fixed position with respect to the fixed support 2. Alternatively, the position, and also the location, of the mixing means 3 can be arranged to be adjustable with respect to the fixed support 2,
especially also in such a way that the mixing means 3 is equipped with adjustment means (not shown) which make possible adjustment of the mixing means during the rotation of the roll 1.
The mixing effect is created by the interaction between the stationary mixing means 3 and the liquid rotating with the rotating roll 1. The surface area, shape and angle of incidence of the mixing means 3 are factors affecting internal flow and the effect of heat transfer. As mixing means 3 can be used, for example, an adjustable-blade propeller, the angle of which can be adjusted to obtain the desired mixing power and shape of flow pattern.
Due to the mixing means 3, the formation of temperature differences inside the roll 1 is prevented. In the roll 1 may be arranged external circulation shown by the arrows 7, the purpose of which is to discharge excessive heat generated during the operation of the roll 1 from the heat-dividing liquid.