USRE21070E - Heating element - Google Patents

Description

May 2, 1939. F. RAFFLES HEATING ELEMENT original Filed Feb. 3, 1934 Reissued May 2, 1939 UNITED ELS Re. 21,076L

HEATING ELEMENT Frankv Raffles, Chicago, Ill.

OriginalNo. 2,014,196, dated September 10, 1935,

Serial No. 709,639, February 3, 17934. Application for reissue June 29, 1937, SerialNo. 151,022

3 C-laims.

'I'his invention relates to an improved heating element and has, fori onezofitsprincipal objects, the provision of a self-contained electrical resistance unit whereby a far greater amount of heat can be concentratedat a given point than hasv heretofore beenconsidered possible.

One of the important objects of this invention is to provide an electrical heating unit or the like which, although made available for Smallinstruments and rather delicate operations, eliminates the necessity-'of a transformer or` any resistance which yhas ordinarily been considered necessary with devices of this sort.

Another important' object of the invention is to provide a heating element wherein the desired temperature is concentrated at the end of the element and over a relatively small area which is especially advantageous in devices of this sort.

Another and still further important object is the provision in a heating element of a novel form of refractory support for the resistance wire which, although of small diameter, possesses considerable strength and which, in connection with a suitable refractory cement, Vwill effectively guard against short circuiting.

One of the definite objects of this invention is to provide a heating element, which can be used in the form of a pencil for pyrography and also for delicate soldering jobs and the like, wherein the source of heat is positioned on a porcelain or some other insulating support which, in turn, is surrounded by a metal element to be used in the transferring of the heat to desired points, the element itself being supported in a pencil-style handle which allows for proper insulation against heat for the protection of the users fingersY and hands.

Another and still further important object of the invention is the provision in a heating element such as the type used in soldering irons or the like of a special winding wherein a constant heat-is always available at any xed voltage such as 110 volts or 220 volts, and which can, furthermore, be suitably and efliciently operated on both alternating and direct current.

Other and further important objects of the invention will be apparent from the disclosures in the accompanying drawing and following specication.

The invention, in a preferred form, is illustrated in the drawing and hereinafter more fully described.

In the drawing:

Figure 1 is an enlarged sectional view of the improved heating element of this invention, showing the pencil-style holder therefor.

Figure 2 isa still-.further enlarged sectional view ofthe heating element itself and its insulating support.

As shown-in thedrawing:

The reference numeral I O-indicates generally a support composed of porcelain or some other suitable refractory material which has an opening I2 extending through the middle thereof, and through this opening is passed a wire I4 which is of the usual high resistance type whereby the passage of a current of electricity therethrough generates considerable heat.

The end of a porcelain tube or support I0 is beveled as best shown at I6 in Figure 2, this bevel extending inwardly to the edge of the opening I2 and over this beveled edge passes the wire I4 which is then brought down below the end of the element I0 and wound in helical shape around the surface thereof as best shown at I8. The spaces between the windings of the wire I8 are lled with a suitable refractory and insulating cement 20 which prevents short circuits and also retains the wire windings I8 in desired position.

The windings I are very closely associated at the outer end of the support ID where the concentration of heat is desired, and toward the rear of the support, the windings are spaced much farther apart as shown at 22 in Figure 1, finally terminating in a pair of extensions which are, in turn, connected to the ends of the usual lamp cord 24 or the like.

'This lamp cord is passed through a suitable opening 26 formed in a handle 28 which is preferably of wood or some similar suitable material and which may be of any desired shape to accommodate the hand and ngers of the user.

A band of cork 30 or some other heat insulating material is usually positioned in a suitable groove formed in the end of the handle element 28, thereby providing for additional heat insulating effects.

The heating element Ill-I8 is itself positioned y in a hollow metal holder 32 preferably cylindrical in shape and which, if desired, may be made pointed at its end as shown at 34 for a still fursmall scale While, at the same time, the amount of heat units delivered is considerably greater than those ordinarily possible with much larger and more bulky equipment.

The closeness of the windings I3, together with the nature of the refractory insulating cement used and the qualities of the high resistance wire itself, permits of a considerable concentration of the heat at the point 34 of the metal heating element 32 which renders this device particularly desirable for pyrography, small soldering jobs,

and the like. e

Another feature is the bevel at I6 on the end of the insulating support I0 whereby the entire support may be more accurately and closely fitted into the tube 32 and whereby a greater quantity of heat is concentrated at the end of the tube which obviously is the point where the most heat is desired in operations of this kind and in using instruments of this type.

I am aware that many changes may be made and numerous details of construction varied throughout a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than as necessitated by the prior art.

I claim as my invention:

l. A heating element, including an insulating tube, a high resistance wire passing through the tube and extending out of the end thereof and terminating in windings around the exterior of said tube end, together with a refractory cement surrounding the Wire and maintaining the same in position on the support, and insulating each coil from adjacent coils, and a metal tube in which said heating element is positioned, the end of said metal tube being exteriorly and interiorly beveled, and a corresponding bevel at the end of the support for the resistance wire, a length of said resistance Wire being positioned in said lastnamed bevel.

2. A heating element, including an insulating tube, a high resistance wire passing through the tube and extending out of the end thereof and terminating in windings around the exterior ofl said tube end, together with a refractory cement surrounding the Wire and maintaining the same in position on the support, and insulating each coil from adjacent coils, and a metal tube in which said heating element is positioned, the end of said metal tube being exteriorly and interiorly beveled, and a corresponding bevel at the end of the support for the resistance wire, a length of said resistance wire being positioned in said lastnamed bevel, and the whole mounted to fit closely in the correspondingly interior beveled end of the said metal tube.

3. An electric heating unit, including a working muzzle, a refractory core tube terminating in the muzzle, a Wire extending through the tube, a resistance coil, and service connections with and for current through the wire and coil; said tube being cemented in the muzzle; said coil formed of a filament Wrapped close on one end of the tube and Wide space Wrapped medially along the tube so as to form a hot zone entirely within the muzzle.

FRANK RAFFLES.

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