US1150426A - Electric heater. - Google Patents

Description

W. S. HADAW'AY, JR.

ELECTRIC HEATER.

APPLI-CATION FILED MN. 28. 1913. 1,150,426. Patented Aug. 17, 1915. 4 SHEETS-SHEET I.

llllllllllllllf Ill 2%? wild/7705M 27M arr/m W. S. HADAWAY, .III.

ELECTRIC HEATER.

APPLICATION FILED JAN.28.1913.

Patented Au 17, 1915.

4 SHEETS-SHEETZ.

W S. HADAWAY, .ln.

ELECTRIC HEATER.

APPLICATION FILED JAN. 28. 1913.

1,150,426. Patented Aug. 17, 1915.

x 4 SHEETS-SHEET 3.

246272556 I fizz/6W1- W. S. HADAWAY, .In.

ELECTRIC HEATER.

APPLICATION FILED JAN.2B| I913.

Patented Aug. 17, 1915.

4 SHEETS-SHEET 4.

U s i) EM J/Zz/HZZZr STATES PATENT OFFICE.

WILLIAM S. HADAWAY, JR, OF NEW ROCHELLE, NEW YORK.

ELECTRIC HEATER.

Application filed January 28, 1913.

To all whom it may concern Be it known that I, WILLIAM S. HADAW AY, J r., a citizen of the United States, residing at New Rochelle, in the county of Westchester and State of New York, have 1nvented new and useful Improvements 1n Electric Heaters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to electric heaters.

This application is a continuation as to the broad subject matter of my application, Serial No. 647,691, electric heating devices, filed September 5, 1911.

In electric heaters it is desirable to maintain the heating and the heated members in close relation to secure an efficient thermal connection. To attain this end it has heretofore been proposed either to enamel the heating member to the heated member or to secure the same thereto by special clamping devices. The former method provides an efficient thermal connection of the members but is unsatisfactory in practice because the enamel eventually cracks and breaks off upon repeated expansion and-contraction of the parts due to heat variations. Devices constructed in accordance with the second method are more durable but do not provide a thermal connection as satisfactory as the enameled devices. Moreover, it is necessary to use comparatively complicated and expensive means for clamping the members together.

One object of my invention is to provide simple means to firmly and permanently hold and support the resistance or heating inemberto the heated member so as to obtain an efficient thermal connection.

In prior constructions it has been neces sary also to devise special heaters to meet the varying requirements demanded by the arts. and in order to make use of said heaters it has been necessary either to construct special apparatus for use therewith or else to modify the existmg equipment to a considerable degree in order to adapt it for electric heating.

Another object of my invention is to provide heating means as a unitary construction complete in itself, which heating means may be made to conform to almost any desired object to be heated and may be readily ap- Specification of Letters Patent.

. water-tight.

Patented Au 17, 1915.

Serial No. 744,724.

plied to existing equipment without first disassembling the same.

Heaters constructed in accordance with my invention are made up preferably of a plurality of units of similar construction whereby any desired area may be heated, regardless of its peculiar formation, by simply assembling sufficient units to equal the desired area to be heated and making said units conform to said area. Heaters so constructed are adapted, for a very wide range of application in the different arts. For eX- ample, they may be used as air heaters or radiators, laundry irons, fiat Work ironers, press heaters, both open and closed forms, tank heaters, immersion heaters, electric stoves, electric machine irons used in hatting work, brim softeners, oven heaters, molding irons, rotary band ironers, heaters for tubes, for air, gas and water, heaters for drying pasted cartons, heaters for linotype and monotyp'e pots, heaters used in celluloid manufacture and many and various other industries, the ramifications of which are too numerous for convenient mention.

In the accompanying drawings I have shown a number of diflerent embodiments of the invention which I have worked out in practice and which will serve to illustrate the unusual adaptability thereof to almost any given condition where heat is required. The invention is, of course, not limited to the embodiments illustrated, as said embodiments are selected merely because they are typical of certain uses to which the invention has successfully been applied.

The views of the drawings are as follows:

Figure 1 is a perspective view on an enlarged scale of the various elements which go to make up an individual heating unit in its most widely used form. Fig. 2 is a perspective view of the assembled elements. Fig. 3 is a top plan view of one form of heater made. up of two parallel units, portions of the upper casings being broken away. Fig. 4c is an end elevation thereof. Fig. 5 is a top plan view of a heater made up of four parallel units united to the top of a rigid plate and inclosed to render the same Fig. 6 is an end elevation thereof. Fig. 7 is a top plan view of part of a siX unit heater showing the resistance ribbons brought out and folded over to form adjacent terminals. Fig. 8 is an end eleva; tion of a heater for large areas, comprising three groups of individual heaters, the heating units of which are integrally united to heat conducting plates, arranged to be pressed against and to cover substantially the entire area of the body to be heated ultimately. Figs. 9, 10, 11 and 12 are end elevations of various open types of heaters showing the same formed integrally with a fieXible support which is thereafter bent around to conform to either the inner or outer curved surface of a cylinder or roll. Fig. 13 is an end elevation of a group of heater units applied to the outer flat surfaces of a body of rectangular cross section. Fig. 14 is an end elevation of a group of heater units applied to the bottom and sides of a channel shaped body. Figs. l5, l6 and 17 are elevations of individual units showing terminals mounted in different positions thereon. Fig. 18 is an end elevation of a body having a large area heated by a plurality of parallel heating units secured directly thereto and requiring no additional external pressure. Figs. 19, 20, 21 and 22 are end elevations of a series of heater units welded directly to either straight or curved surfaces of the elements to be heated. Figs. 23 and 24 illustrate further direct applications of heater units to curved and bent surfaces respectively. Fig. 25 is an elevation of a heater made up of four parallel units welded to a sheet metal base having upright terminals mounted thereon. Fig. 26 is a top plan view thereof. Fig. 27 is an end elevation thereof. Fig. 28 is a sectional elevation of a sheet metal plate having six parallel heater units welded directly thereto. Fig. 29 is a similarly constructed heater but with the units completely inclosed and sealed against moisture. Fig. 30 is a sectional elevation of a similar group of heater units welded directly to a rigid plate. Fig. 31 is similar to the preceding figure except that the units are sealed in. Fig. 32 is a sectional elevation of a modified construction of heating unit wherein separable parts are first welded to-a suitable base and cover which are thereafter assembled. Fig. 33 is an enlarged sectional elevation of one of the assembled units of Fig. Fig. 34 is an enlarged sectional elevation of a further modified form of heater unit. Fig. 35 is a plan view of a disk-shaped heater. Fig. 36 is a sealed-in heater of large area. Fig. 37 is a development of heater of peculiar configuration. Fig. 38 is a perspective view of the heater of Fig. 37 coiled up in the form in which it is used. Fig. 39 is a sectional elevation of a sealed in heater with the'units applied to the inner walls of a channelshaped body. Fig. 40 is a sectional elevation of a sealed in heater with the units welded directly to the inner curved wall thereof. Fig. 41 is a top plan view of a group of heater units arranged for a rectangular stove, showing also a modified form of welded strips for securing the resistance element in place. Fig. 42 is a sectional elevation thereof with some of the resistances removed to disclose more clearly the said strips. Fig.

43 is a similar sectional elevation showing said strips before they are bent over. Fig. 44 is a top plan view of a further modification in the means for clamping the resistances to the sheet-metal container. Fig. 45

is a sectional elevaion of a terminal connection.

The form of heater unit shown in Figs. 1 and 2, is made up of a sheet metal channel 1 which is integrally united to the heated body 2 preferably by welding it thereto.

fiat slotted ribbon of less widththan the ,90

strip of mica 3, is placed over the latter and covered by a second strip of mica 5. Sheet mica spacers 5 may be fitted between the slotted portions of the resistance ribbon to properlv space the latter centrally within the channel, as shown in Fig. 3. A cover plate6 is then placed over the strip of mica 5, said plate having the form of a strip of sheet metal just wide enough to fit loosely within said channel. of the channel are then bent over said cover plate 6 whereby the resistance 4 is firmly clamped between the bottom of the channel and the cover plate, thereby forming a hcating unit, the bottom area of which is firmly and integrally united to the plate 2 and in good thermal contact therewith. The entire structure is then preferably placed in a press and subjected to great pressure. For

example, in certain classes of work,'a pressure of sixteen to twenty tons per square inch is employed. Thus any irregularities in the metal are pressed out and the entire unit rendered very thin and compact, with the resistor separated only a very small fraction of an inch from the base of the channel and hence from the heated body to which said channel is integrally united. The mica, although very thin, affords ample insulation for the resistor, and furthermore it conducts heat readily from the resistance to the channel and hence to the heated body. "I It 1s also well adapted to withstand high temperatures witnout deterioration.

The unit constructed as above has the appearance of a thin fiat strip, somewhat as shown in Fig. 2, except that in reality it is much thinner relatively than as shown in said figure, the latter being purposely drawn somewhat out of proportion to show The bottom of the 35 The vertical flanges 100 clearly the various layers of metal insulation and resistance.

The unit as a whole, considered apart from the body to which it is welded, is flexible, although this is not essential in all cases. That is to sayit may be bent or deformed in almost any direction and at almost any angle within certain practical limits without destroying its efliciency. In other words, the resistance, although deformed, is still effectively insulated from its metal carrier or container and at the same time remains firmly clamped between its inclosing walls. Furthermore, the unit when welded to a flexible support or heated element, may be bent or deformed with said heated element to almost any desired configuration, the combined heating unit and heated element acting as a single integral unitary construction. The fact that the total area over which the channel is welded to said heated element is large insures the bending of these two parts without danger of separation thereof. Accordingly, the thermal efficiency of the heater as a whole is maintained despite said deformation.

The heater unit is not only usually long and narrow but is preferably narrow in any case, regardless of its length, whereby, the resistance is firmly clamped in position and given no opportunity to spring up or away from the bottom of the channel. even when bent. Vhere it is desired to heat a large area or an area having a width greater than the width of the channel, a plurality of channels are welded, usually parallel and side by side to a common heated element, whereby the same degree of high thermal efficiency is maintained for each unit of area of the entire surface, however extensive.

The structure which I provide is capable of being used ad 'antageously in various relations. Various applications of this structure will now be set forth. The body itself may form the working surface or it may be applied to another body which forms the working surface. The body may be bendable so that it can be bent into different forms or made to conform to other bodies. It may be further stated that the heater may be of the open or closed type. Figs. 1 and 2 discloses units of the open type. The units, however, may be sealed in or inclosed in a cover to render them water-proof in a manner hereinafter described.

In Fig. 3 I have shown how two units 7niay be assembled side by side on a common supporting plate or base 8 to which they are welded in the manner previously described. The two adjacent ends of the resistance l are brought out at the ends of their respec tive carriers and constitute terminals, being suitably perforated to receive terminal connectors, various forms of which are hereinafter described. Said terminals are insulated and reinforced to a certain extent by the sheets of mica 3, 5, which are allowed to protrude beyond the end of the carrier as shown. The opposite ends of said resistance may be connected in any suitable manner. One method is to braze a strip of resistance material 9 across said ends as indicated in Fig. 3. It will be seen that although the area of the plate 8 is substantially double the area of each unit, nevertheless, the same high thermal efliciency ismaintained per unit of area, as each resistance is held not only at the opposite margins of said plate, but also at the middle thereof.

In Figs. 5 and 6 a series of four units 7 are arranged side by side and are welded to one side of a rigid plate 10, the lower surface of which constitutes an active face orheatradiating surface, The terminals are simi lar to those previously described, and the ends of the resistances l are electrically connected to the ends of adjacent resistances by the conducting strips of metal 9, brazed thereto in the manner previously discribed, thus giving a series connection. The effective length of the resistance in this case is substantially four times the length of a single unit, whereby the total resistance is proportionately increased. Of course, in some instances it is desirable to apply full voltage to each unit, whereupon a parallel connection is employed instead of a series connection. In this latter case, each unit has a terminal at each end thereof. In the form of heater employing a series connection, it will be seen that an even number of units are employed, whereby both terminals are arranged at the same end of the heater, providing for the convenient attachment of conductors. IV here an odd number of units are employed, the terminals are arranged at opposite ends of the heater, said arrangement being adapted, however, to certain peculiar conditions which may arise in practice.

In the form of heater under discussion, all of the units are suitably incased and rendered watertight by an inclosing plate or casing 11, which is welded around its edges to the rigid plate 10. This plate may be welded either by electric welding or by the use of an acetylene torch, of in other ways. Said plate preferably fits tightly down over said unit, although, as will be apparent, the thermal contact between each unit and the bottom plate is maintained by the welded channel members, entirely independently of said cover plate, and accordingly, if the bottom plate is warped or deformed, due to changes in temperature therein, the cover plate may spring away from or relax whateverpressure it may exert on the individual units without impairing in the least the thermalefliciency of the heater, as each unit conforms to the moistatmosphere, where it is surrounded by steam, for example, or it may be immersed in a liquid and used as an immersion heater,

special forms of immersion heaters constructed in this same manner being hereinafter described.

In Fig. 7 a series of six units are arranged side by side in a manner similar to that previously described. The resistance ribbons of the two outer units. are brought out and folded over in the manner indicated, in order to bring the circuit terminals in a convenient position, close together.

In Fig. 8 I have shown an arrangement for heating a body 12 having a very large heat-radiating face or surface. In this case .it will be assumed that it is not desirable to weld the units 7 directly to said body. Accordingly, the heater units are arranged in a plurality of groups of four units each, the units in each group being welded to a metallic plate 13, whereby each of said plates with its four units, constitutes a unitary construction or independent heater. The three heaters are each held against the body 12 by external pressure, no specific means being illustrated, as the pressure may be applied in various ways which will readily suggest themselves. Although the plates I 13 in this case are primarily heated elements,

they act in reality as agents for conducting.

heat from the units to the body 12, which in this case is the ultimate body from which it is desired to diffuse heat. This same idea of the heated body acting both as an agent for conducting heat to a second body and affording also a convenient base to be clamped to said body, is illustrated in Figs. 9 to 14; inclusive.

In Fig. 9 the individual units are arranged substantially parallel to each other and to the longitudinal aXis of a tube or roll 14, each unit being slightly curved, due to the fact'that itis welded to the supporting plate 15, the latter being curved around practically the entire circumference of the tube and clamped thereto by any suitable means. In this case, the inner surface of the tube is the heat-radiating surface.

InFig. 10 the heating units are welded to the supporting plate 15 substantially at right angles to the longitudinal axis of the roll or tube, whereby each unit is bent longitudinally, as indicated. As shown in this figure a plurality of heating units may be arranged side by side, .each having in effect the form of a hoop, or they may be arranged somewhat in the form of a helix, or in various other ways which will readily suggest themselves. A terminal connector 16 is shown, mounted at one end of the units as illustrating a convenient way of mounting the same; The detailed construction of such a terminal will be understood from a further description hereinafter given.

In Fig. 11, the heater units are arranged in groups of three each on a series of four supporting plates 15, all of the units being parallel and the supporting plates being suitably clamped to the cylinder. In this figure and in the two preceding figures I have illustrated a hollow cylinder, although, of course, the heating units may be applied to a solid cylindrical body, if desired.

In Fig. 12 the plate 17 to which the units are welded, is fitted to the inside of the cylinder, whereby the outer surface thereof constitutes the working face, as in the case of a laundry roll, for example.

In Fig. 13, the supporting plates 19 are each clamped or pressed together against the outer sides of a rectangular hollow body 18, each plate having a plurality of parallel units welded thereto.

In Fig. 14 a channel-shaped member 20 is shown, having plates 19 clamped to the bot tom and outer sides thereof, each plate supporting. a plurality of units, sufficient units being welded to each plate to practically cover the latter.

In Figs. 15, 16 and 17, the various units illustrated have, in each case, a terminal mounted thereon in a different relative position. In these cases the units may be assumed to be welded directly to the heated body 21. In Fig. 15 the unit is welded thereto throughout its entire length. In Fig. 16, the unit is bent upwardly to afford a convenient support for ,the terminal 16, which is similanto the terminal previously described, and in Fig. 17 the end of the unit is bent downwardly.

In Fig. 18 is illustrated a construction wherein the heat is being dissipated from a large area constituting one face of a rigid plate or body 22, to the opposite face of which the heater units are directly welded. The units are arranged substantially parallel and cover practically the entire surface, whereby the heat is conducted directly through said plate to the working face.

In Figs. 19 to 22 inclusive, the heater units are welded'directly to hollow bodies substantially similar to some of those described above, the same reference characters being employed to indicate corresponding or similar parts.

The construction will be clearly understood in view of the preceding description and the utility of the heaters illustrated will I outer and inner walls of the rectangular body are heated.

In Fig. 23 the units are shown welded directly to a rigid plate 23 having a slight curvature.

In Fig. 24 the unit is welded directly to a channel shapedmember or shoe 24, being arranged across the channel with its end upturned as shown. A suitable terminal is also illustrated.

In Figs. 25, 26 and 27, a group of four parallel units is welded to a plate 25, which may be assumed to be either rigid or flexible. The outer margins of the plate project beyond the units as shown. The terminals are mounted in upright positions near one end of the plate. Theheater thus formed is of the open type.

In Fig. 28 the units are welded to a plate 26 which may be either rigid or flexible. The heater thus formed is adapted to be pressed against the. body to be heated and may, of course be bent or curved to conform to said body, although this illustration is intended to disclose a heater for an object having a flat surface against which the heater is pressed.

The construction in Fig. 29 is quite similar to that shown in Fig. 28, except that an additional cover plate 27 is provided, the edges of which are welded to the edges of the plate 26 to form a water-tight joint. This heater is also intended to be pressed against the body to be heated.

Figs. 30 and 31-correspond to Figs. 28 and 29 in certain respects, but differ in that the individual units are welded directly to a thick rigid base or plate 28. In all of these four figures, siX units have been illustrated, although, of course, the number may be varied to meet different requirements. Furthermore, in these and the preceding figures, the units have all been of what might be called a standard construction and arranged parallel and side by side. Said units, however, may be made of more or less irregular outline to conform to irregular areas to be heated or to permit a plurality of units to be fitted together so as'to' cover an irregular area or any desired portion thereof.

In Fig. 32 the units are of modified construction, the enlarged details being shown in Fig. 33. The resistance element 29 is practically surrounded by insulation 30, mica, for example, and arranged in a channel-shaped member 31. Said channel is first welded to a base 32 which is shown as having a channel section. The cover plates 33 for individual units areeach made of a strip of metal folded upon itself in the manner illustrated and welded to the channelshaped cover 34, the latter being adapted to fit within the vertical flanges of the channel 32. In order to assemble the upper and lower channels, it is necessary to slide one into the other longitudinally, the oppositely extending flanges of the cover plate 33 being received within the" bent over portion of the channels .31 as shown in Fig. 32. Pressure is then applied to the upper plate 34, whereupon the parts are firmly pressed together and locked. The upper edges of the plate 34: may be welded to the upper edges of the plate 32, thereby providing a sealed construction. 7

In Fig. 34: another form of heating unit is disclosed. The channel 31 which is sub stantially similar to the channel just described, is welded to the base 32. A resistance and the insulation therefor, which are substantially similar to those just described, are covered by a heavy plate 36 of substantial thickness. The upper inwardly eX- tending flanges 35 of the channel 31 are then bent over said cover plate and the plate 32 electrically welded thereto, the heat capacity of said cover plate being sufficient to permit this welding without injury to the resistance. Units of this type may be arranged in a sealed-in casing similar to that shown in Fig. 31, if desired, or may be used in various other relations. I

In Fig. 35 a circular or disk-shaped hea-te is illustrated. The plate or disk 37, which may be either of flexible metal or a rigid plate, is electrically welded to a sheet metal ring 38, the outer and inner margins of which are flanged over, a second ring 39 constituting the cover plate. The resistance,

which is clamped between rings 38 and 39,

may be of the fiath ribbon type or may be made of resistance wire wound spirally, or it may be made in various other ways. Where the circular area to be heated is of considerable diameter, a plurality of concentric heating'units may be employed, each substantially similar to that described. Circular heaters of this type may be used as disk stoves, that is, stoves having an area about equal to that of a coffee-pot or any other substantially cylindrical vessel, the contents of which it is desired to heat.

In Fig. 36 I have illustrated an inclosed type of heater 40 of large area, the construction of which will be apparent in view of the foregoing description. This heater may either be pressed against the second body to be heated, or it may be used directly as a heater. Its contour may be varied within wide limits to meet difierent requirements.

In Figs. 37 and 38 I have illustrated an immersion heater 41. The construction of this heater will be apparent from the development in Fig. 37. The units 7 are successively shorter, whereby they may be incasedbetween resilient plates having the outline shown, the heater being thereafter rolled up in spiral form as indicated in Flg.

37. A terminal extension 42 is provided rigid body and may also be inclosed by a suitable cover if desired.

In Figs. 41, 42 and 43, I have illustrated a modified form of unit. In the prior constructions the channel member incloses the resistance on both sides, hence the base of the channel is interposed between the resistance and the object to be heated. In the present modification, this additional thickness of metal is dispensed with, the resilient strips 46 being welded to the body to be heated at opposite sides of the resistance and not between said resistance and said body. Said strips may, in the present instance, be riveted to said body if desired. As seen in Fig. 43, some of said strips have angle sections. Other strips, namely the intermediate strips, are U-shaped. The vertical flanges of said U+shaped strips, however are bent away from each other instead of toward each other, as shown in Fig. 42. The L-shaped strips are bent toward the channel strips so as to clamp the resistance and its insulation, and also the cover plate, to the base 47 This type of unit has the advantage indicated, namely, the securing of the resistance in very close proximity to the plate to be heated, the retaining means or clamps being integrally united to said plate.

These units may be used wherever it is not essential to place the units side by side in close contact, as said arrangement necessitates the spacing of said units somewhat apart as shown in Fig. 41.- Where there is room for a spaced construction, rivets may.

be used to hold the resistors, instead ofchannels or angles, in certain cases. p

In Fig. 44 I have illustrated a further modified form of resilient clip for clamping the resistor in position. In said figure a single sheet metal carrier 48 is provided,

which is electrically-welded to the object to be heated and has an area substantially equal to the desired heat-dissipating surface. The outer margins 49, or certain portions thereof, are bent inwardly and lugs 50 are struck up from intermediate portions of.

the plate, said lugs being bent in either one direction or the other to secure a cover plate 51, and hence the resistance, .to said plate. The lugs 50 may be struck up in alternate arrangement as illustrated, whereby one may be bent to the right and one to the left and so on, the object being to provide clamping means integrally secured to the object to be heated and arranged on an intermediate part of the plate, whereby the resistance is firmly clamped as in the preceding devices described, and is prevented from buckling or springing away from the object to be heated, even if the latter should warp or spring. The arrangement of lugs just described, is, of course, merely intended as suggestive of various other ways in which clamps integrally united to the body to be heated may be arranged wherever desired to provide the desired clamping means.

In Fig. 45 I have illustrated a sectional elevation of a terminal showing one way in which the resistance may be readily connected in circuit. At the left of the figure is shown one end of a heating unit 7, the

various superimposed layers being the samev as shown in Figs. 1 and 2. The resistance 4 is lifted and a metallic washer 52 is placed between said resistance and the sheet of mica directly beneath the same. A pair of mica washers 53 are placed between the upper insulating sheet of mica and the metallic cover plate immediately above said sheet. The cover plate has previously been bent, pressed or stamped upwardly as shown to form a boss 54 having an opening therein. A second pair of mica washers 55 is placed on said boss and an L-shaped terminal member 56 is placed on said washers and secured by a metallic eyelet which is headed over at both ends so as to clamp the various parts enumerated firmly between said L-shaped terminal and the metallic washer 52, said terminal bein g thereby electrically connected with the resistance. A screw 57 passes through the upper arm of the terminal 56 and carries a nut 58 and washer 59 between which and said upright arm the conductor may be clamped. The terminal may be protected, if desired, by a metallic cover 60 provided with an asbestos lining 61.

The above described devices have been selected to give a comprehensive idea of the invention and to suggest various phases thereof in its application to the different arts. The invention is, of course, not limited to the embodiments illustrated, nor is it limited to the various kinds of apparatus referred to or suggested herein. In general, it is to be understood that the various words and phrases used throughout the specification have been employed in a descriptive rather than in a limiting sense. Furthermore, I desire to embrace within the scope of the invention, any suitable equivalent means for accomplishing the numerous desirable and advantageous results specified and indicated wherever such means fall within the scope of the appended claims. I

What I claim as new and desire to secure by Letters Patent is:

1. A device of the character described,

comprising a rigid heated member having integral flexible strips and a resistance arranged between said strips and held in position by bent over portions of said strips.

2. A device of the character described, comprising a body having on one side a heat-dissipating surface, flexible strips welded to said body upon its opposite side, and a resistance arranged between said strips and held in position by bent over portions of said strips.

3. A device of the character described comprising a heated member, flexible strips integrally united therewith at a distance from the edges thereof, and a resistance arranged between and held in place by said strips;

4. A device of the character described, comprising a heated member, flexible angle strips having portions integrally united with said member, and a resistance arranged between said strips, said strips having bent over place.

5. A device of the character described, comprising a rigid heated member, flexible strips integrally united therewith, a flat resistance element arranged between said strips, sheets of insulation arranged above and beneath said element, a plate covering said resistance element and said insulation, said flexible strips having portions bent over said plate to press the same and said resist ance element toward said heated member.

6. A device of the character described, comprising a heated member, a flexible channel plate integrally united with said heated member, and a resistance'arranged within said channel plate and held against the same portions holding said resistance in by bent over portions of said plate.

7. A device of the character described,

1 comprising a heated member, a flexible channel plate welded thereto, a resistance element arranged within said channel plate, and a covering plate for said resistance, said resistance being insulated from both of said plates, said channel plate having its edges bent over said covering plate.

8. A device of the character described, comprising a heated member, flexible strips integrally united therewith, a resistance element, sheets of insulation arranged above and beneath said element and being of greater width than said element, and a plate covering said element and said sheets of insulation, said strips having portions bent over the edges of said plate and said insulation.

9. A device of the character described, comprising a heated member and a plurality of sets of flexible strips integrally united with said heated member, said sets of strips being arranged parallel to one another in close proximity, a resistance element arranged between each set of strips and held in position by bent over portions of said strips, said resistance elements being electrically connected.

10. In an electric heater, a body having on one side a heat-dissipating surface, flexible pieces protruding from the opposite side thereof, and resistors arranged side by side and held in position by bentover portions of said pieces.

11. In an electric heater, a body having on one side a heat-dissipating surface, and a plurality of resistances on the opposite side of said body, said resistances being held in place by bent over pieces integrally united with said body.

12. In an electric heater, a body having on one side a heat-dissipating surface, a. plurality of resistances on the opposite side of said body, said resistances being held in place by bent over pieces integrally united with said body, and insulation interposed between said resistances and their immediate supports.

13. In an electric heater, a body having on one side a heat-dissipating surface, a plurality of resistances on the opposite side of said body, said resistances being held in place by bent over pieces integrally united with said body, cover plates between each resistance and said bent over portions, and insulation on opposite sides of each resistance and between said resistances and said cover plates.

14. In a heater, a. bendable metal plate forming a heated element, and a resistance carrier of flexible metal welded thereto, whereby said combined plate and carrier may be given various configurations without impairing the thermal contact between the two.

15. In a heater, a bendable metal plate, and aoplurality of resistance carriers of flexible metal each welded thereto, whereby said combined plate and carriers may be bent in any desired direction Without impairing the thermal efliciency of the heater.

16. In combination, a plurality of substantially parallel heating units, and flexible sheet metal clips for securing said heating units to the object to be heated, said metal clips being integrally united to said object.

17. In a device of the class described, a heated member, and a plurality of heating elements therefor each held in close heatconducting relation thereto by means integral with said heated-member and embracing the margins of said heating elements.

18. In a" device of the class described, a heated member having a plurality of heating units welded thereto, the aggregate area of said units in contact with said member being substantially equal to the desired heatdissipating area of said member.

19. In a device of the class described, a

heating element having integral flexible marginal portions which extend inwardly, intermediate securing means integral with said element, and a resistance arranged between and held by said marginal portions and said intermediate means.

20. In combination, a metallic heat conducting element, and a sheet metal resistance carrier having portions integrally united thereto, said carrier comprising two substantially similar sheet metal pieces of unequal area, the larger piece having its margins folded over the smaller piece to clamp the resistance between the two. 7

21. A device of the class described, comprising a heated member having integral flexible strips and resistances arranged side by side between pairs of said strips and each held in position thereby.

22. In an electric resistance device, a plu- I rality of strips of resistance material, sheets of insulating material above and below said strips of resistance material, a plurality of metallic plates resting upon one surface of one of said series of sheets of insulating material, metallic channels inclosing all of said previously mentioned elements and arranged to compress the same, and means for mechanically connecting said channels.

23. In an electric resistance device, a plurality of strips of resistance material, means I for insulating said strips of resistance material, a plurality of metallic channels inclosing said insulating means, said channels being arranged to compress said insulating means upon said resistance material, means for electrically connecting said strips of resistance material, and means for mechanically connecting said channels.

24. In an electric resistance device, a plurality of strips of resistance material, means for insulating said strips of resistance material, a plurality of metallic channels inclosing said insulating means, said channels being arranged to compress said insulating means upon said resistance material, means for electrically connecting said strips of resistance material, and means for mechanically connecting said channels.

25. In an electric resistance device, aplural- 1ty of strips of slotted ribbon resistance material, sheets of insulation of a greater width than said strips of resistance material on opstrips of resistance material, and means for mechanically connecting said channels.

26. An electric heater comprising a single body, and a plurality of resistors arranged side bysidethereon andheld in position by bent over strips which project from said body.

27 An electric heater comprising a body, flexible strips projecting from said body and forming a plurality of channels, and a resistor arranged in each channel and held in position by said strips.

28. An electric heater comprisin a body, flexible strips projecting from said body at points remote from the edges thereof, and resistors held in position on said body by said strips.

29. The process of manufacturing electric heaters, which consists in integrally uniting flexible strips to a metallic support so that said strips project therefrom, arranging a suitably insulated resistor between a pair of said strips and bending the projecting portions of said strips over said insulated resistor to hold the latter firmly in position benesses. 7

WILLIAM S. HADAWAY, JR. Witnesses i a,

EDWIN N. LIGHTFOOT, Gno. B. JONES.

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