US3201558A

US3201558A - Temperature controlled device

Info

Publication number: US3201558A
Application number: US283078A
Authority: US
Inventors: Lusebrink Elmer Henry
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1963-05-24
Filing date: 1963-05-24
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17
Also published as: GB1000842A

Description

1965 E. H. LUSEBRINK 3,201,558

TEMPERATURE CONTROLLED DEVICE Filed May 24, 1965 2 Sheets-Sheet 1 FIG.

INVENTOR ELMER HENRY LUSEBRINK BY flan 14 ATTORNEY Aug. 17, 1965 E. H. LUSEBRINK 3,201,558

TEMPERATURE CONTROLLED DEVICE Filed May 24, 1963 2 Sheets-Sheet 2 F|G.3 F|G.4

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INVENTOR ELMER HENRY LUSEBRINK ATTORNEY United States Patent f 3,201,553 TEMRERATURE CONTRULLED DEVICE Elmer Henry Lusehrink, New Shrewsbury, N.J., assignor to E. 1. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed May 24, 1963, Ser. No. 283,078 '7 Claims. (Cl. 219-10131) This invention relates to a temperature controlled device for thermally treating moving webs.

Heated rolls and rollers are widely used in a number of different web processing machines in a variety of industrial applications. For example, many calendering and laminating operations, treatments of textiles, drying of paper webs, etc., rely on the use of heated rolls. Generally, these rolls are of considerable mass and are designed to maintain a certain elevated temperature over a long period of time to afford a uniform treatment of a web of great length. Such rolls are usually heated internally by means of steam or electricity. In applications where repeated short, intermittent, thermal web treatments of only a few seconds duration are required, such rolls do not perform satisfactorily. They require relatively long heat-up times and, because of their mass and heat capacity they maintain the elevated temperature for a considerable length of time after the heating means is deactivated.

It is an object of this invention to provide an improved device embodying web processing rollers having rapidheating characteristics. It is a further object to provide a device with such rollers that have a low heat capacity and will cool rapidly when the heating means is de-energized. Another object is to provide rollers that maintain a desired temperature within a narrow limit. A still further object is to provide rollers that can go through a succession of short hot and cold cycles. Another object is to provide such rollers that have minimum deflection under a uniform load and have a hard, smooth surface.

Yet another object is to provide a device embodying such rollers that are inexpensive, operate on normally supplied electric current, are easy to manufacture, and require no maintenance.

The temperature controlled device of this invention comprises, in combination,

(a) A laminated core of high magnetic permeability having a cylindrical section,

(b) A frame for supporting said core,

(c) An electrically conducting coil connected to a source of alternating current and surrounding a portion vniovement of the free end of the roller.

The device of the invention is particularly useful in ofiice copy machines of the photothermographic type in which an image of an original is produced on a receptor sheet by performing a thermal transfer operation from a selectively photopolymerized matrix material. Machines of this type are disclosed in assignees copending patent applications Heiart and Velvel, Ser. No. 234,616, filed Nov. 1, 1962, and Cohen, Ser. No. 250,856, filed Ian. 11, 1963. In these machines the thermal process roller 18 mounted so that it is rotatable only when it is in contact with the moving matrix and a rotating pressure roller.

3.,2111558 Patented Aug. 1?, 1965 Suitable photopolymerizable matrix materials for use in such machines are disclosed in U.S. patent, Burg and Cohen, 3,060,023, issued Oct. 23, 1962, and U.S. patent applications, Burg and Cohen, Ser. No. 163,078, filed Dec. 29, 1961; Heiart, Ser. No. 123,651, filed July 13, 1961; Cohen and Luebbe, Ser. No. 156,518, filed Dec. 1, 1961; and Burg, Ser. No. 234,214 filed Oct. 30, 1962.

The invention is best explained by means of the attached drawings which are part of this specification and in which:

FIG. 1 is a front elevation of a temperature controlled device of the invention in combination with a pressure roller;

FIG. 2 is a front elevation with parts of the ends in section of the process roll and showing the primary windings;

FIG. 3 is a left end elevation of the device.

FIG. 4 is a right end elevation of the device.

FIG. 5 is a plan view of an alternative form of the invention using an O-shaped core and without a support ing frame; and

FIG. 6 is a wiring diagram for a suitable temperature control circuit.

Referring now to FIGS. 1 and 2, the temperature controlled device comprises a tubular metal roller 11 of low heat capacity, e.g., copper, having integral end flanges 12, which roller surrounds and rotates about a section of a fixed laminated iron core 13 and fixed primary coil 14 wound around said core and intervening layer 15 of dielectric material, e.g., paper, mica or polyethylene terephthalate. The tubular copper roll serves as a shorted secondary turn on a transformer and also functions as a heating roller. The laminated iron core acts both as a support for the roller and as a conductor of magnetic flux. The core is supported by an outer frame 16 having depending spaced legs 17 and central arms 18 which support the ends of the core. The frame is made of a metal or metal alloy of high magnetic permeability so as to provide a good flux path between the poles of the iron core.

The primary coil 14- .is energized from a suitable power line and since the windings do not rotate, the power leads can be inserted through suitable holes (not shown) drilled through the insulating bearing blocks 19 that fit into the ends of the roller 11. These bearing blocks are fastened to the core, e.g., they have a light press-fit and the roller rotates on the outer bearing surface of the bearing blocks; also, these blocks radially support the roller. The roller can also move lengthwise relative to the core to compensate for diiferential roller-to-core elongation. Surrounding the bearing blocks 19 are coacting thrust collers 2d the vertical walls of which act as thrust bearing surfaces against which the flanges of the roller press. These bearing blocks and thrust collars are preferably made of dielectric material, e.g., a resin or superpolymer, such as tetrafluoroethylene resin, polystyrene or polymethylmethacrylate.

One end of the core is anchored by means of pins 21 to arm 13. The right-hand thrust collar presses against the inner surface of this arm as a base point for determining elongation of the metal rolier due to temperature increase. The other end of the roller 11 is free to move or elongate laterally due to thermal expansion. The unconstrained end of the roller presses against the thrust collar on the left end of the device. A yoke 22 surrounds the latter thrust collar and is fastened thereto by means of clevis pins 23, extending through suitable holes (not numbered) near the outer ends of the arms of the yoke. The leg 24- of the yoke pivots about shaft 25 which extends across a suitable slot (not shown) in the frame member. The lower end of the leg of the yoke has attached thereto a suitable pin 26 which, in turn, is pivotally connected to a suitable switch 27. The other end of this switch is connected to an adjusting screw 28 the initial current.

. 2% that extends through a suitable threaded opening (not numbered) near the bottom of depending central bracket 29 of the main frame 316.

Switch 27 is a displacement type switch and the movement of the yoke and the legthereof mechanically amplifies the movement of the switch. This switch has 'contact points 3b which contact and separate in response to movement of the leg of the yoke, which in turn is controlled by thermal expansion of the tubular roller 11. These contact points are connected by means of suitable electric wires of the electrical control circuit.

In the embodiment of the invention shown in FIGS. 1, 3 and 4, the heated roller is normally rotated by contact with rotating pressure roller 31 which has shaft extensions 32 that are journalled in suitable bearing in the arms of the frame member. The shaft extension on the right end of the pressure roller can be journalled directly in the frame arm as shown in FIG. 4. However, as shown in FIG. 3, the shaft extension on the left end of the pressure roller is preferably journalled in a separate arm 33 which is fastened to the main arm by means .of bolts 34 extending through holes (not numbered) in .lateral flanges on said arm. These bolts have threaded adjustment with the main arm of the frame. Alternatively, a gear or pulley could be mounted on the roller and rotated by a gear, or a pulley and a belt drive. Also, the core, primary and roller can be made rotatable, the

= core serving as the axle. A driving means could be con- .The laminated iron core 13 is O-shaped and is of the .closed core type. being within the tubular roller, are wound on one side The primary windings, instead of of the core. The metal roller 11, however, constitutes a shorted secondary member of the device. This tubular roller revolves about the other section of the O-shaped 'member as shown in FIG. 5. Antithrust bearing 20-11 is used between bearing block 19-a and member 20.

FIG. 6 shows a suitable electric circuit for the temperature controlled device described above. SW is the main power switch and upon turn-on the power flows through Tsw into the primary windings on the core L and L The windings are placed in parallel to increase After the roller temperature rises and the roller elongates to the set point, the displacement switch Tsw (27 in FIG. 1) opens. When this occurs, relay A picks up and holds itself in through contacts A and condenser C whereupon contacts A and A transfer windings L and L into series, thus reducing the .amount of current in the primary during successive heat -modulation cycles.

R C and R C are arc-quenching means and they are used to protect the relay contacts. The displacement switch acts to maintain the temperature at the set point. When the main power switch SW is opened, relay A drops out and the circuit is re-set to parallel connections between L and L The circuit diagram shows typical values of the various components.

During normal operation of the temperature controlled device of the invention, when switch SW is closed the power flows through the parallel windings in the primary causing an alternating magnetic flux to flow through the core. This flux induces an in the shorted secondary, and eddy currents quickly heat the roll surface. The

heat created causes thermal expansion of the roll resulting in its elongation.

140 volts.

-has good thermal conductivity, a low specific heat, and

low electrical resistivity. However, silver alloy or aluminum rollers, because of their physical qualities, can also be used. The outer surface of the roller can be plated with an appropriate meta-l, such as chromium, to provide a harder and reflective surface. The inside surface can be heat insulated or chrome plated to reduce the heat loss to the primary windings and the iron core. The inside diameter of the copper tubing should be such that only a small space or void 36 exists between the primary winding and the roller. The space should only be so large as to allow the roller to turn around the windings and act as an insulator between the heat produced in the roller and the windings and the core. The closer the tubular roller is to the windings, the better will be the coupling coefiicient, minimizing reactive transformer loss.

In the preferred embodiment, two bearing systems were used, one to allow the roller to rotate and the other to allow the roller to move lengthwise relative to the transformer 'core. 'These solid bearing blocks are made of anti-friction, dielectric materials, as described above. Other bearing combinations that provide for the necessary movements will be obvious to those skilled in the art. For example, the iron core, primary windings, and -the copper roll could be made rotatable by using slip rings to supply the power to the windings.

The preferred temperature control means is based on the elongation of the roller due to the heat produced in it. The elongation of the roller is transmitted by the .linkage to the displacement switch. This switch mechanically amplifies the elongation and when the elongation reaches a set limit, the switch is tripped. The tripping of the switch regulates the flow of the power to the primary windings. There are several types of displacement switches that may be used, such as the Thermoswitch, manufactured by the Fenwal Co., Ashland, Mass, or the Sternco #H-7F, manufactured by the Stevens Manufacturing Co., Mansfield, Ohio.

These displacement switches use the same basic principle. A slight movement, such as that caused by thermal elongation, is transmitted to the switch, which mechanically amplifies the movement. In the switch made by the Fenwal Co., this is accomplished by means of a double 5 cotangent yoke, and when a set displacement is reached the switch is opened. With the Thermoswitch switch, one end may be attached to the linkage and the other end is attached to the frame. A Vernier adjustment attaches the one end to the frame and is used to set the switch-for the desired displacement. This switch will open and close contacts with a differential displacement of approximately 20 10- inches. With a roller temperature of C. as the set point, this switch maintains the temperature within :1" C. (125 roller temperature) with an input voltage change of from 30 to Other type temperature control means can be used, but most contacting type sensing devices such as thermocouples and thermistors cannot accurately follow the rapid rate of the roller temperature rise without overshoot. If an O-shaped core is used, the temperature control means could be an air gap 35. The air gap is shaped to fit the magnetic and thermal parameters of the device in use in such a manner that just enough flux is induced in the secondary to match the heat load in the roller producing thermal equilibrium. Some of the parameters involved are the permeability of the core material, the rate of temperature rise in the roller, the thermal coeflicient of expansion of the copper roller, and the desired temperature set point.

This gap can be spring loaded and will normally be closed when the roller is cold. When it is closed, there will be maximum core flux transmission. As the roller heats, lineal expansion forces the core gap open and the core flux and coupling is reduced. With this type of temperature control, the transformer primary must swing, i.e., it must offer low impedence to a heavy load and oifer high impedence to a light load. If a proper relationship between the roller elongation and the gap opening is obtained, the roller Will remain at a desired temperature when the temperature control point and the input energy rate are complementary; thus the assembly can be self-controlling. This type of device has an obvious advantage of having a continuous input power, modulated by thermal demand.

A typical roller of the type shown in FIGS. 1 and 2, having a roller length of ten inches, composed of one inch inside diameter copper tubing with a wall thickness of 0.025 attained a temperature of 125 C. from a cold start (25 C.) in seven seconds, requiring an input of 110 v. at 8 amperes.

The process roller of this invention can be varied as to its size, but to have high performance an optimum relationship of at least four related parameters should be obtained, i.e., the dimensions of the heated roller, the physical properties of the heated roller, the transformer characetr-istics, and the characteristics of the temperature controller.

The process roller device of this invention has many advantages over the prior art. The rollers are rapid-heating and self-regulating. They are relatively inexpensive, but highly eificient. The control circuitry is simple, small, of low weight, and can be adapted easily to small equipment. The roller device can handle webs of any length, single sheets or rolls. The temperature is controlled according to the demand, so that heating cycles of a few seconds or of any longer time can be maintained.

Iclairn:

1. A temperature controlled device for thermally treating a sheet comprising in combination (a) a core of high magnetic permeability having a cylindrical section,

(b) a frame for supporting said core,

(c) an electrically conducting coil connected to a source of alternating current and surrounding a portion of said core,

(d) a tubular metal roller having a high coefiicient of expansion, good thermal conductivity, low specific heat and low electrical resistivity surrounding the cylindrical section of the core and journalled on spaced insulating bearing blocks mounted on said core,

(e) one end of said roller being restrained from axial movement and the other being free to move axially, and

( f) a switch in the electrical circuit for the coil for energizing and deenergizing the coil in response to axial movement of the free end of said roller.

2. A device according to claim "-1 wherein said tubular roller surrounds said coil.

3. A device according to claim 1 wherein said coil is disposed on a portion of said core that is not surrounded by the roller.

4. A device according to claim 1 wherein said roller is composed of copper;

S. A device according to claim 1 wherein said roller is composed of copper having a chromium plated inner and outer surfaw.

6. A device according to claim 1 wherein said roller is composed of aluminum.

7. A device according to claim 1 wherein said core is laminated.

References Cited by the Examiner

UNITED STATES PATENTS

2,27 3,423 2/42 Somes 21910.49

References Cited by the Applicant UNITED STATES PATENTS Re.23,619 2/ 5 3 Weller. 2,301,589 11/42 Shepard. 2,541,416 2/51 Harrison. 2,643,475 6/53 Klopfenstein.

RICHARD M. WOOD, Primary Examiner.

Claims

1. A TEMPERATURE CONTROLLED DEVICE FOR THERMALLY TREATING A SHEET COMPRISING IN COMBINATION (A) A CORE OF HIGH MAGNETIC PERMEABILITY HAVING A CYLINDRICAL SECTION, (B) A FRAME FOR SUPPORTING SAID CORE, (C) AN ELECTRICALLY CONDUCTING COIL CONNECTED TO A SOURCE OF ALTERNATING CURRENT AND SURROUNDING A PORTION OF SAID CORE, (D) A TUBULAR METAL ROLLER HAVING A HIGH COEFFICIENT OF EXPANSION, GOOD THERMAL CONDUCTIITY, LOW SPECIFIC HEAT AND LOW ELECTRICAL RESISTIVITY SURROUNDING THE CYLINDRICAL SECTION OF THE CORE AND JOURNALLED ON SPACED INSULATING BEARING BLOCKS MOUNTED ON SAID CORE, (E) ONE END OF SAID ROLLER, BEING RESTRAINED FROM AXIAL MOVEMENT AND THE OTHER BEING FREE TO MOVE AXIALLY, AND (F) A SWITCH IN THE ELECTRICAL CIRCUIT FOR THE COIL FOR ENERGIZING AND DEENERGIZING THE COIL IN RESPONSE TO AXIAL MOVEMENT OF THE FREE END OF SAID ROLLER.