US1708995A

US1708995A - Electric soldering iron

Info

Publication number: US1708995A
Application number: US120562A
Authority: US
Inventors: Charles C Abbott
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1926-07-06
Filing date: 1926-07-06
Publication date: 1929-04-16
Anticipated expiration: 1946-04-16

Description

April 9 9- c. c. ABBOTT 1,708,995

ELECTRIC SOLDERING IRON Filed July 1926 v Inventor:

Charles C. Abbott,

cnannns c.

ABBOTT, F PITTSFIELD, MASSACHUSETTS, ASSIGNOR. TQ GENIER ELECTRIC CUMPANY, A co flRATlolt OF NEW YORK.

ELECTRIC SQLDERENQ IMN.

Application filed July 6, 1928. Serial No. 120,582.

My invention relates to electric soldering irons and has for its object the provision of a simple, reliable and eficient device of this character.

In carrying out my invention in one form 1 provide an electric heating unit consisting of a metallic casing in which a resistance heating element is secured. A soldering copper is secured to one end of the casing, while a handle is secured to the other end of the casing. My invention also comprehends improvements in the electrical connections for the resistance heating element.

Fora more complete understanding of my invention reference should be had to the accoinpanying drawing in which Fig. 1 is a view mainly'in section of an electric soldering iron embodying my invention; Fig. 2 is an enlarged sectional view showing the electric heating unit; Fig. 3 is a sectional view along the line 33 of Fig. 2; Fig. A is an en larged plan view of a terminal member with the resistance wire connected thereto; Fig. 5 is a sectional view of Fig. 1 taken along the line 55 looking in the direction of the arrow while Fig. 6 is an enlarged plan view of an insulating member used in the connection of the conductor cord to the terminals of the electric heater.

Referring to the drawing, in carrying out my invention in one form 1 provide an electric heating unit comprising a metallic sheath or casing 10, preferably tubular, in which a heating resistance element 11 is secured. As shown, the heating resistance 11 is a wire made of a suitable material, such as a nickel chromium alloy. It is wound helically on a cylindrical support 12 made of suitable electrically insulating material, such as lava. The ends of the resistance wire are secured to metallic terminal members 13 and 1A, which.

may be made of the same material as the resistance wire, the terminal members being inserted in longitudinal apertures or

bores

13 and 14 provided for them in the support 12. In order to provide for the connection of the endsof the resistance wire with the

terminal members

13 and 14, each terminal member is provided with a longitudinal slot 15, Figs. 4 and 5, the two terminal members being identical in construction. This slot begins at one end of the terminal member and terminates just short of the other end. The end of the resistance wire is folded over to form two or more parallel lengths which are twisted together, as indicated by the numeral 16. As shown, three lengths are twisted together. This twisted portion 16 is placed in the groove 15 and then the side walls of the groove are pressed together or peened over an intermediate section of the twisted ortion, as indicated at 17 and 18. The en s of the twisted portion project from the peened over walls of the groove, and, due to the constriction of the intermediate length, efiectively secure the twisted portion in place. As connected with the terminal member 1 1, the resistance wire extends from the open end of the groove, but in the terminal member 13 the twisted portion 16 is reversed so that the wire passes out laterally from the opposite end of the groove, as shown in Fig. 2.

ln assembling the resistance wire and terminals on the support 12, the resistance wire is secured to the terminal 14, and the terminal 14 inserted in its aperture 14$, the resistance wire being laid in a longitudinal groove 19 provided for it in the support 12 and brought to the opposite end of the support where it is laid in a cross groove 20 in the support and brought out at the opposite side. The resist ance wire is then wound helically on the support toward the opposite end and sufficient slack is left in the resistance wire after the winding operation to permit the terminal 13 to be connected as previously described and then inserted in its aperture 13 in the support, the resistance wire extending through a longitudinal slot 21 in the support. After the terminal 13 has been put in place the re sistance wire is tightened by twisting the terminal one or more revolutionawhereby one or more turns of the resistance wire are wound around the terminal 18 to take up the slack. The edges of the groove 15 are rounded 0d at 15 and 15 at the region where the wire is brought out laterally, in connection with terminal member 13, so that the wire will not be injured when wound on to take up the slack. This form of connection provides a very reliable mechanical and electical joint and also allows the resistor to be readily assembled on the support 12.

The oore'12 with the resistance wire thereon is embedded in the sheath 10 in powdered heat refractory insulatin material 22, such as magnesium oxide w ich is preferably compacted so as to secure the core and heating resistance in' place and also to increase, the heat conductivity of the powdered me- 26 and 27 of the terminal members.

terial. As shown in the drawing, the turns of the resistance wire are suitably spaced apart on the core, the powdered insulating material being packed between the turns. This compacting operation may be carried out in any suitable manner, for example, by reducing the diameter of the sheath, as by swaging or rolling, after the unit has been assembled.

The end of the sheath opposite the

terminal members

13 and 14 is closed by means of a metallic washer 23, the end of the sheath being spun over to secure the washer in place. In the opposite or terminal end of the sheath is a washer 24 made of insulating material, such as mica, and a porcelain insulator 25, apertures being provided in the the washer and insulator for the protruding end lengths To improve their flexibility the

lengths

26 and 27 may be made of twisted wire. As shown, these protruding ends or terminals are somewhat smaller than the terminal member portions inside the unit, a shoulder being thereby formed at the junction of the two portions on which the insulating washer 24 is seated. The end of the sheath 10 is spun over a shoul der 28 provided on the insulator 25. In addition to acting as an insulator, the washer 24 acts as a cushion or bufi'er to prevent cracking of the porcelain insulator from the end pressure caused by the swaging operairon.

The soldering copper 29 is secured directly to the sheath 10, and as shown, the sheath is provided with threads 30, and the soldering copper 29 with a tapped bore adapted to receive the threaded portion of the sheath, as shown in Fig. 1. The screw threaded engagement between the soldering copper and the sheath provides a good thermal contact between these parts so that heat is conducted freely to the soldering copper. Preferably a fairly loose fit is provided bet-ween the soldering copper 29 and the sheath so that the soldering copper may be removed easily even after oxidation of the threads. This does not appreciably affect the thermal contact since a good contact is obtained between the sides of the threads when the sheath strikes the bottom of the bore. This conduction of heat is further improved by the fact that the soldering copper extends throughout the greater part of the length of the casing 10. It will further be observed that the heating element 11 extends from a point adjacent the left hand end of the casing 10, as viewed in Fig. 2, throughout the greater part of the length of the casing, the soldering copper being substantially coextensive with the heating element.

The sheath 10 is secured to a handle 31 by means of a helically shaped member 32, helical V shaped

grooves

33 and 34 being provided in the sheath and the handle respectively to receive one or more end turns of the member 32. The member 32 is made of spring steel or other resilient material so that the end turns expand slightly when screwed on the sheath and the handle. It will be observed, however, that any attempt to twist the member 32 in the opposite direction to remove it, serves only to further contract the end turns and secure it more firmly in place. In order to facilitate the removal of the member 32 from the sheath 10, this end is beveled in the manner indicated in Fig. 3 so that a substantially V shaped space 35 is formed with bottom of the groove. A pointed tool, such as a screw driver, may be inserted in I this space and used as a lever to lift the end of member 32 and Work it back out along the groove. Preferably the helical member 32 is V shaped on its inner side so as to fit into V shaped grooves in the sheath and the handle.- The threads 30 are preferably formed or cut in the sheath 10 after the heating unit is assembled and compacted, the sheath being originally of sufficient thickness to provide for them.

The protruding

end lengths

26 and 27 of the terminal members are threaded through cylindrical porcelain insulators 36 each of which is provided with two

parallel holes

36 and 36" adapted to receive the

lengths

26 and 27. As shown in Fig. 2, the insulators 36 are each provided with a concave surface at one end and with a convex surface at the other end, the convex surface of one insulator fitting into the concave surface of the adjoining insulator. The outer end of the insulator 25 is also provided with a convex surface over which the adjacent insulator 36 fits. This arrangement of convex and concave surfaces serves to interlock the various insulators and secure them against lateral displacement. By means of the insulators 36 it will be ob served that an insulating bushing is formed around the

terminals

26 and 27, which bushin extends centrally of the member 32 into a ore 37 provided in the handle 31 Where electrical connections are made between the ends of the terminals and an insulated twin conductor 38. This twin conductor extends through a somewhat smaller bore 37 in the handle and it is provided with a suitable connection device, such as a plug by means of which the soldering iron can be conveniently connected to an electrical supply circuit.

In making the connection between the ends of the terminals and the twin conductor 38, a strip 39 of electrically insulating material such as fibre, is used. Referring to Fig. 6, this strip is cut out at one end at 40 so as to fit over the convex surface of the end insulator. It is also provided with pairs of oppositely disposed notches 41 and 42, with two

apertures

43 and 44, and with a concave edge 45 at the opposite end. As shown in Fig. 1, the strip 39 is placed between the two terhandle, said member and said handle being minals to form twisted joints 46. Before the twisted connections are made, the insulated conductors are threaded through the two

holes

43 and 44, each being passed through a hole, whereby the twisted conductor is se-' cured to the strip 39. The two insulated conductors are seated in the concave end 45 of the strip 39. The ends of the terminals are secured to the strip 39 by tying them with a cord made of a suitable insulating material, such as linen, the cord being wrapped around the strip in the pair of notches 42, as indicated.

by reference numeral 48. The twisted joints 46 are folded over on the strip and secured by a wrapping 49 of cord which is laid in the pair of notches 41. The insulator strip 39 sepa rates the twisted connections 46 and insulates them from each other, while the wrappings I of cord'secure the connections to the strip and prevent the strip from slipping. Any pull which might be accidentally or otherwise applied to the twin conductor cord is applied directly to the stri 39, the end of which rests against the shoul er formed at the junction of

bores

37 and 37, since the cord is secured to the strip, and cannot be transmitted to the twisted connections.

While I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with theprovisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric soldering iron comprising a metallic cylindrical member provided with a bore, a handle secured to one end of said member, a soldering copper secured to the other end of said member surrounding said member thoughout the greater part of its length, and heating means in said bore.

2. An electric soldering iron comprising a hollow metallic member, a handle, a helical member connecting said member with said member, a soldering copper secured to and slubstantially surrounding said metallic member, and heating means in said metallic member.

3. An electric soldering iron comprising a hollow metallic member, an electric heating element in said member extending from. a point adjacent one end throughout the greater portion of said member, a soldering copper secured to said member at said end extending substantially coextensively with said heating element and a handle secured to the other end of said member.

4. A soldering iron comprising a hollow metallic member, a handle, a helical member connecting said member with said handle, said member and said handle being provided with grooves at one end to receive said helical member, and said member being threaded throughout substantially the remainder of its length, a soldering copper provided with a threaded bore fitting on the threaded portion of said member, and heating means secured within said hollow metallic member.

5. A soldering iron comprising a soldering copper, a resistance heating element therefor, a handle attached to said copper,said handle being provided with a longitudinal bore having an enlarged portion in the end adjacent said copper whereby a shoulder is formed within said bore, a strip of insulating material in said enlarged portion provided with apertures and resting against said shoulder, an insulated conductor extending through said bore threaded back and forth through said apertures, and a connection between said conductor and said heating element.

6. A soldering iron comprising a metallic member, a resistance heating element therefor, a handle secured to said metallic member, said handle being provided with a longitudinal bore having an enlarged portion in the end adjacent said metallic member whereby a shoulder is formed within said bore, a

strip of insulating material in said enlarged tures, and a connection between said con uc- I tor and said heating element.

In witness whereof, I have hereunto set my hand this 29th day of June, 1926.

CHARLES C. ABBOTT.