claimed is: 1. In an electrically lieated soldering iron, a heat conducting core liavin- an extension thereon constituting a solderin(r tip, a lieating unit surrounding said core,'a casin- sui-- 45 rounding said heating iinit and havin- an open end beyond whic-li the tip portion of the core extends, and a stipportin- member for said core comprising a pltirality of radially exteiiding arms sectired to the casing wall and a cylindrical portion in engage- 50 ment with said -%vall only at its end. - 2. In an electrically heated soldering iron, a heat conducting core havino, an extensiort thereon constituting the sol-'dering tip, a heating unit surroulading said core, a casino, 55 surrounding said heating unit and havin" an open end beyond which the tip portion of the core extends, a stipporting member for said core having only a small portion of its surface area in contact with said casing, 60 and heat insulating material between the major surface of said supporting membeland said casing. 3. In an electrically heated soldel-ing iron, a heat conducting core han,in- an extension 65 thereon constituting the soldering tip,. ,I heating unit surrounding said core, a casiii,r surrounding said heating unit ana lia-,-inff an open end beyond which the tip portioii of the core extends, heat insulating inatei-iil 70 interposed between said heating unit aii(I said casing, a supporting membe foi, sai(I core having only a gmall portion of the stirface area in cont,,tet witli said casing, aii(I Ileat insulatino- material interposed betiveeii 75 the major surface of said supportin- menil)er and said casing. 4. In an electrically heated solderiiil(, iron,, a heat conductin- coi-e havin- aii exterisjoii thereon constituting a soldering til) in(I pi-o- 80 vided with a screw threadecl pol-tion intei-- mediate its ends, a heating unit surrotin(iiiii, said core, a casin(r stirroundin(r said heatiii,,- iinit and lian,ing an open end bevond wl)icli the tip poi-tion of the core exte'nds, tild 1, 85 supporting member for saicl, core coml)rlsing an internally screw tlireaded sleen-e adapt@d to encraue the threads on said core to ti in secure said c-ore in place and a pltii-alit@, of i-adially extending arms on said sup or . ting 90 p member adapted to be seciii-e(I to the casin(v ivall. In witness whereof, ive beretinto subscribe our names this tliird day of July A. D., 1919. JAMES T. GRIFFIN. WILLIAM A. TIMM,

UNITED STATES PATENT OFFICE. JAMES T. GRIFFIN, OF OAK PAP.]K, AND WILLIAM A. TIXX, OF 13FRWyN, ILLINOIS, ASSIGNORS.TO WESTERN ELECTRIC COMPANY, INCORPORATED, O:F NEW -YORK, N. Y., A CORPORATION. OF NEW YORK. ELECTRICALLY-HEATF,D SOL3)FP.ING-IRON. 1,400,156. Specification of Letters Patent. Patented Dec. I 3 , 1 9 2 1 . Application filed July 17,.1919. Serial No. 311,499. To al'& Whom it may coneem: Be it known that we, JAmFs T. GRIFFIN and WILLIAir A: Timm, citizens of the United States residing at Oak Park, in the county -of -C6&-k and State of Illinois, and Be yn, in the county of Cobk and State rw Of Illinois, respectively, have invented certain new and useful Improvements in Electrically-Heated Solderin,gIrons, of 'which the following is a full, clear, concise, and exact description. This invention relates to electrically heated solderinl, irons, and its object is to produce a sold'ering iron in N@hich the he,,it of i5 @he heating unit will be directed to the soldering tip without waste by radiation, thereby enabling the heating unit to bd worked at a much lower tem]perature than has heretofore been possible, whereby the 20 cost of operating the iron will be reduced to a minimum, and the deteri6ration of the heating element from burning out will also be reduced. In accordanee with the general fe,,ttures 25 of this invention the heating unit and the conducting core, through which the heat is carried to the tip,'are so separated and insulated from the outside shell in which they are located that the loss of heat by 30 radiation is greatly reduced. In the prefe@red form of this invention the heating Unit is separated from the outside casing by means of heat insulating material, and the conducting core, through which the heat @5 is carried to the tip of the iron, is so mofinted in this casing that a minimum amount of metal will come between the core and the casing, thereby reducing the radiating surface through -which the heat from the core 40 might be transmitted to the casing. In the drawings illustrating this inventionFigure l' is a, view showing a section throug4, the working parts of the iron; 45 Fig. 2 is a sectional view taken upon line 2-2 of Fig. 1 ; Fig. 3 is a s6etional view taken upon line 3-3 of ilig. 1; Fig. 4 is a detail view of the means for 50 supporting th-- core within the casing, and I Fig. 5 iig an efilarged cross-sectional view through the core itself indicating a nonoxidizable coating thereon. As show in the drawings, 5 designate--- a heat conducting core upon the outer end of 56 -kvhich is provided a conventional soldering tip 6. Near its outer end the core 5 iS PrOvided with screw threads 7 adapted to engage internal screw threads in a supporting member or nut 8 by means of which it is 6o removably held withiii a casing 9. Located within the casin- 9 and surrounding the core 5 is a heating -unit comprising a helically wound heat generating coil 10 embedded in t cylindrical spool 11 of refractory mate- 65 rial such as alundum cement. Applied %vli ile in a plastic condition to the outside of the spool 11 is a layer 12 of some suitable heat insulating material mixed with u arabi c. The location of this layer 12 ofin@ 70 sulati on outside of the heating unit and inside of the casing 9 prevents the heat from the heating unit reaching this casing and bein g radiated into the 6pen air and causes it to be directed against the -ore 5 through 75 - @vhich it is transmitted to th.e tip 6. At its outer end the casinly 9 is sdun ove'r into a, conical form, as indicalred at l@, and has an opening 16 therethrough through which the tip 6 of the core 5 extends without touch- 80 ina the ivalls of the casing 9. Located within'ilii s end of the casing 9 is the suppo@ting mem ber or n'ut 8 which is screw threaded to rece ive the threaded portion 7 of the core 5. As shown, this supporting member or nUt 85 8 is provided with tlire6 radially extending lugs 18----18 which are adapted to bear igain st the inside of the wall of the casing 9 and to be secured thereto by means of pins 20- 20. An extended cylindrical @ortion 21 90 of this supporting member engages at its martgion the inside of the tapered or conical pori n 15 of the casing 9, the surf ace of enzage ment being limited to a very small area. Pack ed aroulid this supporting member 8 96 betw een the cylindrical portion and the wall of the casing 9 and between the supportink lugs 18-18 of the nut 8 is a suitable heat insul ating material mixed with gum arabic. This confines the heat generated to the core,100 5 and prei,ents it reaching the wall of the casing 9 except through the very small radiating surface of the lugs 18-18 and the end of the cylindrical portion 21. At its inner end the casing 9 is provided 105 with an internal screw threaded portion 25 adapted to encra(ye a screw threaded portion 26 on the enIRrg@cl end 27 gf P, stem 29 which

1,400,156 is.connected with a handle 29 through which conductors 30 may be led to the Ileating unit. Insulating wash6rs 31-31 of asbestos are inserted between the end of the core 5 and the end of the stem 28 and leads 32-32 dre led through these washers to the connecting terminals (not shown) Within the stem portion 28 of the iron. An, insulating washer 33 of asbestos may also be inserted between the 10 end of the heating unit and th,p supporting member or nut S. A thin'coating 35 of nickel is applied to the core 5 of the soldering iron to prevent oxidation of this core and preserve its heat 15 conducting qualities. The core 5 may be removed for replacement by unscrewing it from the s'upporting member 8. The heating unit may be removed by unscrewi@-ig the shell 9 from the 20 stem 28. It will be apparent that with an iron made in accordance with this invention, in which the heating unit,is thoroughly insulated by heat ins'ulating material from the shell to' 25 the the heat generated. in the, heating iron, unit will be substantially all directed against the conducting core, and that by means of the method oi mounting the core, whereby but a very small portion of it is in metallic so connection with the outside casing the maximum heat will be directed from the heating unitintotheconductingcore thusprovidin-a c6nstruction in which ihe h'eating unit may be worked at a lower temperature and at a 35 lower current consumption, thereby prolonging the life of the iron and enabl.ing the use of materials for the heatinu unit which it has heretofore been found inipossible to use for this purpose. 40 What is