US2739218A - Heating rolls - Google Patents

Description

March 20, 1956 WENNERLUND 2,739,218

HEATING ROLLS Filed May 20, 1953 INVENTOR. Ka -MM United States Patent HEATING ROLLS Eric Wenneriund, Ludvika, Sweden, assignor to The Ohio Brass Company, Mansfield, (This) Appiication May 20, 1953, Serial No. 356,261

13 Claims. (Cl. 219-37) My invention relates to that part only of an apparatus for forming laminated tubes of paper or other suitable material and has particular reference to laminated cores for condenser type bushings.

It is of extreme importance that condenser type cores shall be of uniform structure and density throughout in order to meet the exactin" requirements of such a device and each core should be the equal of each other core for uniformity of product.

Therefore, the apparatus upon which the core is produced must be absolutely suited to meet the requirements. The core is normally produced on a set of rolls suitable for windin prepared paper or other suitable material to form a uniform laminated body.

One of the most important elements of such a machine is the heating roll of which one or more is used to properly soften the insulating binder on the material being wound, just prior to the paper web becoming a part of the core, the web being precoated with the binder.

One object of this invention is to provide heating rolls or cylinders which shall be uniformly heated and the temperature maintained, and the degree of heat quite accurately controlled and varied by the operator to meet the softening points of the different insulating binders used in forming condenser type cores of laminated formation and uniform density throughout.

The roll is also suitable for use in machines for drying a Web, such as a web of damp paper or a paper web which is wet with printing.

In the treatment of certain materials with heated or hot rolls, difficulties often arise in obtaining an even heating over the entire roll. This is especially the case in winding machines for the manufacture of t cores by winding paper upon itself about an arbor or conductor red, the paper having been precoated with Babelite varnish or other suitable insulating adhesive. When the process concerns the roll on which the paper is wound, the paper will act as a heat insulation, and when it concerns the roll or rolls which are heated and bear against the paper as it winds, the latter will conduct the heat away from the roll. The consequence is that the ends of the roll are warmer than the middle of it.

In order to obtain an even temperature all over the surface of such tells, it has earlier been the practice to heat them by steam, hot oil or other medium in gas or liquid form which is caused to circulate through the rolls by means of pumps. This method, by itself excellent, has, however, the great disadvantage that it is difiicult, especially at high temperatures to secure and maintain tight joints between the pipe feeding the heating medium to the roll and the rotating roll.

The present invention concerns an arrangement by which this disadvantage is completely avoided and according to the invention this is obtained by providing the heating roll with one or more confined spaces, partly filled with a medium which is liquid, at least when hot ice and which distributes the heat evenly throughout the heating roll as it rotates.

The means for heating the liquid within the roll is stationary and independent of the roll proper so that the roll rotates relative to the heating means with no physical connection whatsoever with the heating means.

The roll may for instance consist of two concentric cylinders closely joined with each other at their ends by ring shaped covers whereby the space or receptacle between the cylinders may be kept sufiiciently filled with a liquid having a suitable boiling-point.

The cylinder may also be constructed solid but provided with a plurality of individual channels which extend from one end of the cylinder to the other and which may each be closed by end caps. The last'mentioned arrangement can be of advantage if the heating rolls each have a small diameter.

As the transmission of heat inside the cylinder chiefly takes place by evaporation and condensation of the liquid according to the principle of the cold wall in order to get the greatest heat-transmission at certain temperature, it is important that the space in the cylinder is free as much as possible from permanent gases. If, for instance, Water is used, the air dissolved in it should be liberated before the space in the roll is definitely closed.

In the drawing- Fig. l is a vertical section through the longitudinal axis of a roll.

Fig. 2 is a full transverse section of a roll according to Fig. 1.

Fig. 3 is a vertical section through the longitudinal axis of another roll.

Fig. 4 is a full transverse section of the roll according to Fig. 3.

Fig. 5 discloses a means of supporting an electric heating element independent of the cylindrical portion of the roll.

Fig. 6 discloses means for supporting a dilferent form of electric heating element thanthat of Fig. 5.

Fig. l of the drawing shows an embodiment of a roll in which 1 signifies the outer cylinder and 2 the inner cylinder. The two cylinders are joined with each other by ring shaped end plates 6, welded at the ends of the cylinder as indicated at w. The single space or chamber 4 between the cylinders contains a liquid 4' which has a suitable boiling-point and the whole roll is heated by an electric heating element 5 placed in the center or here 9 of the roll. Journals 7 project from eachend of the roll and 3 designates a paper web in contact with the roll.

Fig. 3 shows an arrangement of a roll consisting of a cylinder 8 provided with a central bore 11 in which the heating arrangement 5 is placed. The cylinder is provided with several channels 10 situated concentrically around the central bore 11. These channels are closed at the ends with ring shaped plates 12 Welded to the roll, and the channels may be connected with one another by one or both circular grooves 13 which are formed in the ends of the roll or inner face of the plates 12. The channels it) are partly filled with a medium 4' which is liquid when hot. The channels may each be either independent of each other as by omitting the grooves 13, the preferred construction is shown in Fig. 3, and forming in eifect the single recess, by which construction a more effective heating is obtained and thus also a more uniform temperature secured throughout the roll.

Fig. 5 shows a portion of one end of the heating element 5 and the manner in which it may be supported independent of the roll by the standard 25 and heat resisting insulation 26.

The electric heating element 5' shown in Fig. 6 is a single type element supported at each and beyond the ends of the journals 7 by the standards 25 and heat resisting insulation 26.

In order to maintain the temperature of the rolls uniform through out the operation of forming the cores, it is essential to provide means to regulate the temperature by controlling the heating of element 5. This may be accomplished in various ways, two of which are disclosed in Figs. 1 and 3. V

In Fig. 1 a control board 20 is provided on which is mounted an ammeter 21, a rheostat22 and a switch 23, under control of the operator, who by watching the operation of the winding machine, can manipulate the rheostat accordingly. The heater and the several devices are connected to a source of electric current by means of conductors 16 and 17.

In Fig. 3 is a modification thereof in that a thermal switch 24 is introduced in the control circuit 17 which maintains a constant temperature of the roll by automatically open- .ing and closing the circuit as the temperature of the roll requires. The thermal switch 24 may be of any suitable type maintained in contact with the rotating roll but stationary relative thereto.

Having described the heating roll according to my invention, it will be noted that the heating medium is contained in air tight chambers 4 and chambers 10. Each roll (Figs. 1 and 3) is provided with a suitable means for fillingand emptying the cylinders controlled by one or more plugs 30.

After the heating medium, say water, has been placed in the cylinder and the heating element 5 operated to heat the water to the steaming stage to drive out the air from the cylinder, the cylinder is closed by replacing the plug 30.

The rolls are used in a horizontal position in the winding machine and rotate about a horizontal axis; the outer surface of the heated roll is engaged by the web as it moves across the same. a

The roll of Figs. 1 and 3 is only partially filled with th heating liquid in order to allow space for expansion when heated. The liquid filler, however, extends above the longitudinal axis of the roll.

A pipe with spaces opening along its length may be substituted for the electric element 5 or 5' and the pipe connected to a source of gas supply, as a means of heating the roll and liquid medium.

The resistance element 5 or 5 may be of carbon or of a suitable high resistance metal.

What I claim as new and desire to protect by Letters Patent of the United States is set forth in the following claims.

I claim:

1. A hot cylinder for use in a machine for uniformly winding a web of prepared material onto a metal arbor comprising, an elongated rotatable cylindrical member, the inner wall of the cylindrical member forming an open end tubular bore extending axially throughout the length of the cylindrical member, the cylindrical member recessed between the wall of the bore and the outer wall of the cylindrical member for the length of the member, the recess and the bore being non-communicating, stationary heating means positioned in the bore independent of the wall and removable through an end opening of the bore, the heating means extending substantially the length of the bore whereby the inner wall of the cylindrical member will be uniformly heated, means by which the heating means may be brought to the required temperature, means closing each end of the recess means, a fluid heating element contained in the said recess to uniformly distribute the heat throughout the cylindrical member, and means at each end of the cylindrical member to support the cylindrical member in a horizontal and rotatable relation independent of the heating means.

2. A hot roll according to claim 1 characterized by the heating element being liquid at the working temperature of the cylindrical member and having a suitable boiling point, whereby the heat of the cylindrical member is uniformly distributed throughout its length.

3. A hot roll for a winding machine constructed according to claim 1, characterized in that the heating means within the bore also comprises means for electrically connecting the heating means to a source of electric current, and thermal control means associated with the roll and with the connecting means to open close the connecting means, whereby the temperature of the roll is automatically maintained as required.

4. A hot roll for a winding machine comprising, an elongated cylinder, a second elongated cylinder of less diameter than that of the first cylinder, the cylinders of substantially the same length and the cylinders mounted in concentric relation, means closing the ends of the space between the concentric cylinders thereby forming a closed receptacle with a hollow interior for holding a liquid heat distributing medium, means extending from each end of the roll to support the roll in horizontal rotative relation with the other parts of the winding mechanism, heating means positioned within the second cylinder and fixed support means for the heating means at each end of the roll so that the roll rotates about the heating means.

5. A hot roll according to claim 4 in which the heating means comprises an electric element subject to heating by an electric current, and controlled means to connect the element to a source of electric current.

6. A hot roll for a winding machine comprising, a pair of elongated concentric cylinders of such relative diameter as to provide a space therebetween for the length of the cylinders, a plate at each end of the said space between the cylinders and secured thereto to seal the space and form a closed recess between the cylinders and hold the cylinders for holding a heat distributing medium in spaced relation, means at each end of the roll to support the same in rotative relation to the winding mechanism, and fixed electrical heating means positioned in the bore of the inner cylinder and extending substantially the length of the roll whereby the inner cylinder is uniformly heated throughout its length.

7. A hot roll as set forth in claim 6 characterized by the electrical heating means connected to a source of electric current, control means associated with the electric circuit for regulating the temperature of the inner roll.

8. A hot roll as set forth in claim 6 characterized by the recess between the cylinders provided with a heating medium that partially fills the said recess and is liquid at the working temperature of the roll whereby the temperature of the inner cylinder is uniformly transmitted to the outer cylinder. 7

9. A hot roll as set forth in claim 8 in that the electrical heating means is electrically connected to a source of electric current and means associated with the electric circuit for controlling the temperature of the heating means whereby the temperature of the heating medium in the said recess may be controlled.

10. A hot roll for a winding machine comprising, an elongated outer cylindrical member with a central cylindrical member provided with a bore extending the length of the cylindrical member, the outer cylindrical member provided with a plurality of spaced parallel longitudinal channels positioned between the outer surfaces of the cylindrical members and terminating at the ends of the outer cylindrical member, means closing the ends of the space between the cylindrical members beyond the ends of the channels to interconnect the channels at the ends thereof whereby the said channels form closed recess means surrounding the said central cylindrical member ing the outer contact surface of the cylindrical member to the required temperature as the cylinder turns about the heating means.

11. The invention in accordance with claim 8 and including thermal control means connected to the electrical heating means and responsive to the temperature of the outer one of the eccentric cylinders for regulating the temperature of the heating means.

12. A roll for a winding machine comprising a hollow outer cylindrical member, an inner cylindrical member concentrically disposed within the outer member having the ends thereof projecting beyond ends of the outer member to provide bearing means on which the roll may be turned, a plate at each end of the outer cylindrical member, each joined to the outer cylindrical member and to the inner cylindrical member about the peripheries thereof to form a closed interior space adapted to hold a heat distributing medium and a longitudinal bore axially through the inner member for accommodating a stationary heating means about which the roll may be rotated.

13. The invention in accordance with claim 12 including longitudinal channel forming means disposed within the space between the said inner and outer cylindrical members, said channel forming means being spaced from the end plates to form passages through which the heat distributing medium can circulate between the channels.

References Cited in the file of this patent UNITED STATES PATENTS 963,942 Richardson July 12, 1910 1,037,573 Allen Sept. 3, 1912 1,168,171 Crumbaugh Jan. 11, 1916 1,268,990 Moeller June 11, 1918 1,587,963 Knopf June 8, 1926 1,819,534 Akerlow Aug. 18, 1931 2,131,336 Sullivan Sept. 27, 1938 2,474,759 Schmitz June 28, 1949

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