US1713845A - Electric soldering iron - Google Patents

Description

Mayzl, l929 E. A. LocKwoon 1,713,845

ELECTRIC SOLDERING IRON Filed Nov. 22, 1926 7x/Ma aa Afa/ami' ff www Auw. 1mm #64M Patented May 21, 1929.

UNITED STATES PATENT omnes.

EBWIN A. LOCK'WOOD, 0F ROYAL OAX, MICHIGAN, ASSIGNOR TO AMERICAN ELECTRI- CAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORATION 0F MICHIGAN.

ELECTRIC SOLDERIN G IItON.

Application `led November 22, 1926. Serial No. 150,018.

The invention relates to electrically heated instruments and more particularly to electric soldering irons of the type in which a central metallic core member is heated by an electrical resistor surrounding the same in close proximity thereto.

With instruments of this type as heretofore constructed it has been the usual practice to form the electrical resistor by winding a conductor circumferentially of the core member and spaced therefrom only by a thm layer of insulation, such as mica. When such a construction is subjected to alternate heating and cooling, it has been found that the metallic conductor gradually contracts in length and this contraction increases the tension on the windings so that they are drawn more tightly around the rigid core member. Since this core member is unyielding, the tension sometimes increases to such an extent that a failure occurs, thus destroying the resistor and requiring a replacement unit.

The primary object of this invention is to provide an improved resistor constructlon so arranged as to permit contraction of the windings under various temperature conditions wit-hout placing any material additional tension on the conductor, thus avoiding ally danger of breakage from this cause. This object has been attained by providing the novel construction hereinafter more fully described, which consists essentially in arranging the windings to extend longitudinally of the core and to be spaced circumferentially thereof.

The conductor is preferably wound upon a tubular insulating member, which, while normally holding the windings in fixed relation, is neverthelesssuiliciently yieldable to permit lengthwise contraction of the conductors without subjecting' them to any increased tension.

In the drawings:

Figure 1 is a longitudinal section the soldering iron;

Figure 2 is a perspective view showing the method of assembling the resistor on the core;

Figure 3 is a view of the resistor as wound prior to being formed into a tube;

Figure 4 illustrates the resistor'after being formed into a tube.

In the preferred embodiment of my invention as illustrated in the drawings, A represents the hollow cylindrical metallic core through preferably formed of a material resistant to I' high temperatures. B is the metallic tip inshank G. H is the outer shell sleeved'on the` forward portion of the core and retained in position by the lock nut H.

The resistor D is preferably formed as illustrated in Figure 3 by winding a resistance element on a flat rectangular sheet of insulating material, such as mica. This fiat sheet I is provided with notches J on its opposite edges which receive the windings K. The resistance element is preferably in the form of a flat ribbon L and this is wound around the flat sheet l forming a continuous resistance unit. After the resistance element has been wound onv the flat sheet, the latter is bent into tubular form with the windings extending longitudinally thereof. The opposite edges M and M gether, forming a split tube which is placed around the spool portion of the core A. For insulating the resistor from the core it is preferable to insert a layer of mica N between the core and the tubular resistor` and a similar layer of mica O is wrapped around the outside of the resistor. Surrounding the insulation O a metallic sheet P is placed and the whole structure is retained in assembled position by a binding of wire, as indicated at Q, the convolutions extending circumferentially.

lVith the construction described it will be apparent that any contraction of the resistor windings due to alternate heating and cooling of the instrument will tend to shorten the windings in a direction longitudinally of the core and this is permitted due to the yieldable nature of the mica tube on which the resistor is wound. This contraction, howof the sheet are brought towindings on the mica sheet I are of slightly lshorter lengths for one-half of the circumference of the tube than for the other half, leava semi-circular portion R between the ends of the windings and the edge of the tube. The terminal S is transversely bent at S and arranged circumferentially of the tube 1n the portion R and again transversely bent at S2 to extend outwardly from the tube. The other terminal T is directly extended outward from the tube at the edge M, the arrangement being such that the two terminals leave the tube at diametrically opposite points. The terminals at these points are encased, preferably in an armor U, andare threaded through inclined passageways V in an insulator block V. The terminal construction at this point is similar to that described in Patent No. 1,425,- 983.

parent that I have provided 'a'resistor construction which can be assembled on a central y up by the contraction of the metal inthe conductors after repeated use.

What I claim as my invention is: 1. A resistor unit for electrically heated instruments having a cylindrical core, said unit i including a tubular resistance element surroundlng said core and formed of a mlca sheet 35' having a conductor wound around the same with the windings extending longitudinally and spaced circumferentially thereof, and a binding member surrounding said tubular resistance unit and insulated therefrom.

2. A resistor unit for electrically heated instruments having a cylindrical core, said resistor unit comprising a thin sheet of insulating material wrapped around said core to surround the same, a conductor Wound around said sheet, the windings extending longitudinally of said core and being spaced circumferentially thereof, insulating material on the inner and outer sides of said resistor, a metallic sheet wrapped around said resistor unit, and a binding element surrounding said sheet and wound circumferentially thereof.

3. A resistor unit for electrically heated instruments having a cylindrical core, said unit including a thin-walled tube ofy insulating From the above description 1t will be ap-l material, a conductor wound on said tube with windings extending longitudinally and spaced circumferentially, the windings of one end of said tube extending further longitudinally for one-half of the circumference than the other half, one terminal from said windings being extended circumferentially of said tube to a point diametrically opposite the other terminal, and a bushing carried by said core at the terminal end of said windings and provided with inclined' passageways for said terminals.

4. A resistor unit for electrically heated instruments having a cylindrical metallic core, said unit comprising a tubular insulator surrrounding said core, a resistance element wound on said insulator with the windings extending longitudinally and spaced circumferentially thereof, the windings being return bent over the edges of said tube and the return-bent portions on one half the circumference projecting further longitudinally than on the other half, one of theterminals o f said windings extending circumferentially of said tubular insulator adjacent the return-bent portions of shorter length, said terminal leaving said tubular insulator at a point diametrically opposite the other terminal.

5. A resistor unit comprising a sheet of insulating material formed into a tube, a flat conductor ribbon wound on saidy sheet to extend longitudinally thereof,'the windings be'- xing spaced circumferentially of the tube and extending for substantially the entire periphery thereof, the opposite ends of said windings terminating at adjacent points and one of said ends beingcarried circumferentially of said tube to a point diametrically opposite the other.

'6. A resistor unit for electrically heated instruments having a core, said unitincluding an insulator surrounding said core, a conductor wound on the insulator with the windings extending longitudinally thereof, the said windings varying in length adjacent one end of said insulator for the purpose set forth.

7. A resistor unit for an electrically heated instrument having a core, said unit including a substantially cylindrical insulator surrounding said core, and a resistor wound on said insulator with the windings extending longitudinally on opposite sides thereof.

In testimony whereof I aiix my signature.

ERWIN A. LOCKWOOD.

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