FI108252B - Method and device for equalising local heat stresses - Google Patents

Abstract

The invention relates to a device and a method for equalising local heat stresses in a rotating, liquid- containing roller 1 in a paper, cardboard or post- processing machine. The device according to the invention is characterised by the device having a fixed steady 2 extending into the roller 1, at least in one end of the roller 1 and co-axially with the rotational axis of the roller 1, one or more mixing means 3 arranged to extend from said steady 2. <IMAGE>

Description

108252

Method and device for balancing local heat loads

The present invention relates to a method and apparatus for balancing the local thermal loads of a rotating liquid-containing roll on a paper / board or finishing machine.

A solution is known in the art in which water is used inside the rotating roller to equalize local heat loads. The water is circulated by a separate 10 external pumps or the water is enclosed in a roll without circulation.

The purpose of heat equalization is to eliminate the increase in the center diameter of the roll, particularly due to the uneven heat load on the polymer rolls. This increase in diameter results in a reduction of the edge load 15. This, in turn, causes so-called paper. crying gloss profile.

In all cases, the known solutions have not achieved fully satisfactory heat equalization.

It is an object of the invention to provide a simple, efficient, reliable and inexpensive method and apparatus for balancing heat loads.

This object is solved by the device and method disclosed in the claims.

25

The device according to the invention is characterized in that the device includes: ·. a fixed support extending at least from one end of the roll into the roll coaxially with the axis of rotation of the roll, from which one or more mixing members are arranged.

30

The method according to the invention is characterized in that the flow of liquid within the rotating roll and thus rotating with the roll is controlled by means of one or more mixing means stationary within the roll.

108252 2

The mixing effect of the liquid results from the interaction of the stationary mixing member and the fluid rotating with the rotating roll. The mixing effect in turn balances local heat loads. The area of the mixing member and the angle of attack are factors affecting internal flow and heat transfer efficiency. The power control settings of the mixing element may be varied while driving or may be set at a fixed level.

Advantageous further developments of the invention are set forth in the dependent claims.

10

The invention will now be described in more detail with reference to the accompanying drawing, which schematically shows a fluid-filled rotating roller equipped with a heat equalizer according to the invention.

In the drawing, a rotary (arrow 6), liquid-filled roll of a paper / board or finishing machine is generally designated 1. on which roll 1 rotates.

The device for balancing the thermal loads comprises at least one end 2 of the roll 1, which extends coaxially with the axis of rotation of the roll 1 inside the roll 1, from which one or more mixing members 3 are arranged.

The fixed support 2 may be arranged to extend over the entire length of the roll 1, as shown in the drawing example, or the fixed support 2 may be shorter and extend over only a portion of the length of the roll 1 from either or both flanges 5.

• ·

The mixing member 3 may be arranged in place with respect to the fixed support 2. Alternatively, the position and also the position of the mixing member 3 may be arranged to be adjustable with respect to the fixed support 2, in particular also so that the mixing member is provided with non-shown adjusting members which allow its adjustment during rotation of the roller.

The mixing effect results from the interaction of the stationary mixing member 3 and the fluid spun with the rotating roller 15. The surface area of the mixing member 3, the shape of the angle of incidence, are factors affecting internal flow and heat transfer efficiency. The mixing element 3 can be, for example, a thrust propeller, the angle of which is adjusted to obtain the desired mixing power and flow pattern shape.

Due to the mixing means 3, the formation of temperature differences within the roll 1 is prevented. The roller 1 may be provided with an external recirculation as shown by arrows 7 for the purpose of removing excess heat generated during operation of the roller 1 from the heat equalizing fluid.

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Claims (7)

Apparatus for equalizing local heat loads of a rotating liquid-containing roll (1) of a paper / board or finishing machine, characterized in that the apparatus comprises at least one end of the roll (1) inside the roll (1) coaxially with the roll (1). a fixed support (2) extending with the axis of rotation, from which one or more mixing members (3) are arranged. Device according to Claim 1, characterized in that the fixed support (2) is arranged to extend over the entire length of the roll (1). Device according to Claim 1, characterized in that the mixing element (3) is arranged in a fixed position with respect to the fixed support (2). Device according to Claim 1, characterized in that the position of the mixing member (3) is arranged to be adjustable with respect to the fixed support (2). Device according to Claim 1, characterized in that the position of the mixing member (3) is arranged to be adjustable with respect to the fixed support (2). 20 Device according to Claim 1, characterized in that the mixing element (3) ·· is provided with adjusting means which enable it to be adjusted during rotation of the roller (1). Method for equalizing local thermal loads of a rotating liquid-containing roll (1) in a paper / board or post-processing machine, characterized in that the flow of liquid within the rotating roll (1) and thus rotating with the roll is controlled by one or more rolls (1). ) by means of a stationary mixing member (3). 108252