GB1561941A - Cooling or heating roller - Google Patents

Abstract

The heat exchange roller for treating flexible webs, and pulverulent or pasty material rotates about an axis (1). It has a cylindrical roller surface (2), two roller end faces (3) rigidly connected thereto and bearings (4) for the roller on the fixed hollow shaft (5). The hollow shaft is divided centrally by a partition (6). The sections (7 and 8) formed by the division are connected to feed and discharge devices for the medium. They communicate through bores (9, 10) with the interior of the roller. The medium can be fed and discharged in the direction of the arrows. In this cooling and heating roller, the internal medium circuit thereof is maintained in a simple way even in the case of complete filling with a liquid heat transfer medium. <IMAGE>

Description

(54) A COOLING OR HEATING ROLLER (71) I, ERICH PAGENDARM, of German Nationality of Fangdieckstrasse 70-76, 2000 Hamburg 54, Western Germany, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a cooling or heating roller with a rotatably supported roller shell which, by means of an internal drum disposed therein, encloses an annular chamber for containing a heatexchange fluid and whose axially opposite ends are interconnected by a communicating chamber situated within the internal drum which supports at least one rib that projects towards the roller shell and increases the velocity of the fluid relative to that of the said drum shell.

Efforts are made to achieve a high thermal transfer coefficient and a temperature distribution which is uniform over the shell surface of cooling or heating rollers. The rate of flow of heat-exchange fluid through the rotating bushing of the bearing system for the roller should be as low as possible. Recent designs therefore attempt to achieve a circulation of the fluid in the interior of the roller so that the quantities of fluid conducted through the rotating bushing are restricted to the value required for dissipating or supplying heat.

The circulation of fluid through the annular space enclosed between the roller shell and the internal drum in a known cooling or heating roller is driven by diffuser ribs which project from the internal drum to the roller shell and are helically inclined with respect to the axial orientation of the roller. The said diffuser ribs are able to apply a pumping force to the fluid in the axial direction only if the said fluid is retained in the circumferential di rection. In the known roller, this condition is satisfied by steam heating so that a liquid portion of the fluid only partially fills the roller and therefore, due to dwelling in the bottom region, unable to follow the circumferential motion.This arrangement cannot be used for rollers which are completely filled with a heat-exchange liquid, because the liquid would be entrained by the rotation of the roller and would therefore have no relative velocity with respect to the ribs and cannot therefore be pumped thereby. In such cases, the circulation of the liquid within the roller is driven by a circulating pump disposed therein and whose shaft extends through the hollow roller trunnion or the liquid supplied to the roller is used as a medium for driving an injector in the interior of the roller. Both procedures are complex.

According to this invention a cooling or heating roller with a rotatably supported roller shell which, by means of an internal drum disposed therein, encloses an annular chamber for containing a heat-exchange fluid and whose axially opposite ends are interconnected by a communicating chamber situated within the internal drum which supports at least one rib that projects towards the roller shell and increases the velocity of the fluid relative to that of the said drum, wherein the rib extends substantially axially along the internal drum which is arranged for relative rotary moveshell, and an impeller, fixed to the roller shell, is disposed on at least one end of the annular chamber.

Conveniently, the rib is constructed as a scraper which bears on the inside of the roller shell and thus counteracts the formation of deposits and interface layers so that the thermal transfer is further improved.

It is also advantageous if the abovementioned communication chamber contains a heating or cooling device for the fluid.

The invention may be performed in various ways and two specific embodiments with possible modifications will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 an axial section, Figure 2 a transverse section along the line A-B of Figure 1, Figure 3 an embodiment which is an alternative to Figure 2, Figure 4 the velocity vectors of the medium in relation to the roller shell, and Figure 5 a partial section in the circumferential direction along the line C-D of Figure 1.

The cooling or heating roller, which can be used for treating flexible webs, pulverized or pasty material, is constructed as a member adapted to rotate about the axis 1 and comprises a roller shell 2 and two roller end faces 3 rigidly connected thereto and bearings 4, disposed in said end walls, for supporting the roller on a stationary hollow shaft 5. In the illustrated embodiment, it is provided with a mechanical shaft seal. The hollow shaft is divided in the middle by a bulkhead 6 and the portions 7 and 8 formed by such division are connected to supply and delivery means for the heat-exchange fluid or thermal medium and communicate through ports 9 or 10 with the internal chamber of the roller so that the fluid can be supplied and discharged in the direction of the arrows.

An axially parallel radial wall 11 is rigidly mounted on the hollow shaft, as shown in Fig. 2, and extensd close to the internal surface of the roller shell 2 and nearly over the entire length of the roller.

An internal drum 12 is rigidly mounted on said wall 11, concentrically with respect to the roller shell 2. Together with the internal surface of the roller shell 2, it encloses an annular chamber 13. The axial ends are situated at a distance from the roller end walls 3, said distance being at least of the same order tof magnitude as the radial extent of the annular chamber 13.

It is taken for granted that any known techniques can be employed for supporting the roller on the hollow shaft 5, for the construction of the hollow shaft, for supplying and discharging the thermal medium or heat-exchange fluid and for mounting the internal drum. For example, the medium can be supplied to and discharged from the same side. The internal drum could be mounted on the hollow shaft by means of a plurality of spokes.

A pump impeller wheel 14, which is fixedly joined to the roller, is provided in at least one of the spaces between one end of the internal drum 12 and an end wall 3 of the roller. The means of mounting are not shown in the drawings. However, it is advantageous for such mounting to be performed on one end wall of the roller or on parts thereof disposed radially in the interior, so that the impeller wheel and its mounting elements do not disturb the uniform temperature distribution within the roller shell.The pump impeller wheel 14 is provided with blades which are arranged, for example as shown in Fig. 5, so that the angle of inclination thereof compared with the direction of the rib 15, formed by the wall 11 and projecting outside the internal drum 12 towards the drum shell, is such that a pumping action is obtained in co 'operation with the rib 15 and the pump impeller wheel 14 which move relative to each other, thus leading to the circulation indicated by the arrows at the top of Fig.

As indicated in the drawing, a single pump impeller wheel is sufficient in normal cases for both directions of rotation.

A corresponding pump impeller wheel will be provided on the other end of the internal drum if a more powerful pumping action is to be achieved. If the blades of both pump impeller wheels are inclined in the same direction and both are situated in the same flow circulation, the same magnitude of circulation will be advantageously obtained for both directions of rotation.

Instead, each of the two pump impeller wheels can be associated in mirror-image configuration with its own flow circuit by interrupting the internal drum in the manner disclosed by the German Offenlegungsschrift 1,775,394.

According to Fig. 4, the relative velocity of the thermal medium in the annular chamber 13 comprises the relative circumferential velocity 16 and the axial velocity 17 induced by the pumping action, both of which are geometrically added to form the greater effective velocity 19. If the rib 15 is stationary, the relative circumferential velocity 16 of the medium in relation to the roller shell will be approximately equal to the circumferential velocity of the roller shell. If it is desired to increase this velocity component, the internal drum with the rib 15 can be set into rotation opposite to that of the roller shell. However, in such cases it is usually simpler in terms of construction for the axial velocity 17 produced by the pumping action to be increased by suitable design of the pump impeller wheel o; pump impeller wheels.

It is an important feature that the rib 15, projects from the internal drum 12 to the roller shell, extends substantially axially with the system so that the summation of circumferential and axial velocities illustrated in Fig. 4 can actually be obtained.

Precise axial parallelity of the rib is how ever not essential.

Fig. 3 shows the embodiment of the rib 15 in the form of a scraper with a thin scraper blade 19 which is resiliently prestressed against the internal surface of the roller shell 2. In the illustrated case, the said rib is symmetrically effective in both directions of rotation. The blade could however also be constructed so that it acts in only one direction. The scraper blade prevents deposits lodging on the internal surface of the roller shell and thus ensures unobstructed thermal transfer. The blade also destroys the thermal medium interface which adheres to the roller shell and thus improves thermal transfer.

It can be seen that the communication chamber 20 situated within the internal drum 12 can contain heating or cooling devices for the medium, not shown in the drawing. For example, means can be provided for supplying or discharging the heating or cooling energy in a form other than the thermal medium itself.

The rib which projects from the internal drum and extends axially prevents the medium from following the rotating motion of the roller shell. This feature has already been disclosed by the US Patent Specification 3,022,047.

The action of the described arrangements is based on the following two effects. The first effect causes the rib to act as a diffuser surface in relation to the pump impeller which co-rotates with the roller shell, and therefore provides the pumping function even when the roller is completely filled with medium. The principle of the second effect is that a relative velocity, corresponding to the geometric sum of the circumferential speed of the roller shell in relation to the internal drum and the linear velocity of the medium, is imposed thereon relative to the speed of the roller shell.

Despite the simple construction, the arrangements enable the medium to have a velocity relative to the roller shell which is substantially greater than either the circumferential velocity or the axial velocity.

In the described arrangement the internal circulation of the heat-exchange fluid is maintained in a simple manner even if the roller is completely filled with heatexchange liquid.

WHAT I CLAIM IS: 1. A cooling or heating roller with a rotatably supported roller shell which, by means of an internal drum disposed therein, encloses an annular chamber for containing a heat-exchange fluid and whose axially opposite ends are interconnected by a communicating chamber situated within the internal drum which supports at least one rib that projects towards the roller shell and increases the velocity of the fluid relative to that of the said drum, wherein the rib extends substantially axially along the internal drum which is arranged for relative rotary movement between the drum and the roller shell, and an impeller, fixed to the roller shell, is disposed on at least one end of the annular chamber.

2. A roller according to claim 1, wherein the rib functions as a scraper and bears on the inside of the roller shell.

3. A roller according to claim 1 or claim 2, wherein the communicating chamber contains a heating or cooling device for the fluid.

4. A roller according to any one of the preceding claims, in which the drum is stationary.

5. A roller substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, or Fig. 3, or Fig. 5, of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. directions of rotation. The blade could however also be constructed so that it acts in only one direction. The scraper blade prevents deposits lodging on the internal surface of the roller shell and thus ensures unobstructed thermal transfer. The blade also destroys the thermal medium interface which adheres to the roller shell and thus improves thermal transfer. It can be seen that the communication chamber 20 situated within the internal drum 12 can contain heating or cooling devices for the medium, not shown in the drawing. For example, means can be provided for supplying or discharging the heating or cooling energy in a form other than the thermal medium itself. The rib which projects from the internal drum and extends axially prevents the medium from following the rotating motion of the roller shell. This feature has already been disclosed by the US Patent Specification 3,022,047. The action of the described arrangements is based on the following two effects. The first effect causes the rib to act as a diffuser surface in relation to the pump impeller which co-rotates with the roller shell, and therefore provides the pumping function even when the roller is completely filled with medium. The principle of the second effect is that a relative velocity, corresponding to the geometric sum of the circumferential speed of the roller shell in relation to the internal drum and the linear velocity of the medium, is imposed thereon relative to the speed of the roller shell. Despite the simple construction, the arrangements enable the medium to have a velocity relative to the roller shell which is substantially greater than either the circumferential velocity or the axial velocity. In the described arrangement the internal circulation of the heat-exchange fluid is maintained in a simple manner even if the roller is completely filled with heatexchange liquid. WHAT I CLAIM IS:

1. A cooling or heating roller with a rotatably supported roller shell which, by means of an internal drum disposed therein, encloses an annular chamber for containing a heat-exchange fluid and whose axially opposite ends are interconnected by a communicating chamber situated within the internal drum which supports at least one rib that projects towards the roller shell and increases the velocity of the fluid relative to that of the said drum, wherein the rib extends substantially axially along the internal drum which is arranged for relative rotary movement between the drum and the roller shell, and an impeller, fixed to the roller shell, is disposed on at least one end of the annular chamber.

2. A roller according to claim 1, wherein the rib functions as a scraper and bears on the inside of the roller shell.

3. A roller according to claim 1 or claim 2, wherein the communicating chamber contains a heating or cooling device for the fluid.

4. A roller according to any one of the preceding claims, in which the drum is stationary.

5. A roller substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, or Fig. 3, or Fig. 5, of the accompanying drawings.