US3521215A

US3521215A - Resistor with end terminals

Info

Publication number: US3521215A
Application number: US764421A
Authority: US
Inventors: James R O'keeffe
Original assignee: Dale Electronics Inc
Current assignee: Dale Electronics Inc
Priority date: 1968-10-02
Filing date: 1968-10-02
Publication date: 1970-07-21
Anticipated expiration: 1987-07-21

Description

July 21, 1970 J. R. OKEEFFE '3;521215 I ,RESISTOR WITH END T ERMINALS Filed Oct. 2, 1968 fg'f l INVENTOR.

Z4/i155 fe @Jeff' United States Patent Gfce 3,521,215 Patented July 21, 1970 3,521,215 RESISTOR WITH END TERMINALS James R. OKeeife, Hastings, Nebr., assignor to Dale Electronics, Inc., Columbus, Nebr., a corporation of Nebraska Filed Oct. 2, 1968, Ser. No. 764,421 Int. Cl. H01c 1/14 U.S. Cl. 338-332 Claims ABSTRACT 0F THE DISCLOSURE A resistor with an elongated core element having a resistance element on the outer surface thereof, and terminal wires secured to the ends of the resistor and engaging the outer periphery of the resistance element at the opposite ends thereof.

This invention relates to a resistor and more particularly to a resistor of the continuous wound type and the method of making the same. This invention also relates to resistors wherein the resistance means is comprised of deposited carbon, metal film or the like.

Resistors of the type disclosed 4herein consist generally of a core overwound with resistance wire and terminals electrically connected to the resistance wire at opposite ends of the core. The problem that the resistor industry is facing is to develop a satisfactory method of terminating the continuous wound resistors which provides good mechanical strength and electrical contact between the terminals and the resistance wire and which does not allow the resistance wire to shift on the core or to protrude from the end of the resistor. Several different methods of termination have been attempted but all have proved to be expensive and unreliable to various degrees. One method used heretofore was to weld the lead wire to the terminal. A second method used heretofore was to insert the lead wire through slits formed in the terminal. A third method used heretofore was to pinch the lead wire between the ends of the terminal stock. These three methods require that the fiber glass or the like core overwound with resistance wire be cut to length prior to the attachment of the terminal. When so cut, the core and resistance wire unravel thereby causing shorted turns, poor electrical contact, poor mechanical strength, and resistance wire protruding from the terminals. Certain of the manufacturers of resistors have attempted to solve the unraveling problem by several methods including core impregnants, insulated wire, etc. These remedial methods have also been generally unsuccessful due to their expense and unreliability.

Therefore, it is a principal object of this invention to provide a resistor wherein the core and the resistance wire do not become unraveled during the manufacture thereof.

A further object of this invention is to provide a resistor having a liber glass core and resistance wire overwound thereon which does not become unraveled during the manufacture thereof.

A further object of this invention is to provide a resistor wherein the resistance wire does not objectionably prou trude from the resistor.

A further object of this invention is to provide a resistor which has good electrical contact between the resistance wire and the terminals.

A further object of this invention is to provide a resistor which has good electrical contact between the terminals and the lead wires.

A further object of this invention is to provide a resistor which has excellent mechanical strength.

A further object of this invention is to provide a method of making a resistor wherein the terminalsare attached thereto before the core is cut to length.

A further object of this invention is to provide a machine process method of making a resistor which does not require core impregnation or other similar methods of adhering the resistance wire to the core.

A further object of this invention is to provide a method of making a resistor which provides two terminations per machine cycle.

A further object of this invention is to provide a method of making a resistor which eliminates a secondary operation to bond the lead wire to the terminal.

A further object of this invention is to provide a resistor which is economical of manufacture, durable in use and refined in appearance.

These and other objects will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, and combination of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:

FIG. 1 is a side view of the resistor with a portion thereof cut away to more illustrate the invention;

FIG. 2 is an end view of the resistor of FIG. 1;

FIG. 3 illustrates one of the initial steps in the method of making the resistor wherein the wound core and lead wire are fed into the machine in parallel paths and the terminal stock is fed perpendicularly to the lead wire;

FIG. 4 illustrates the components of the resistor after the terminal stock has been cut and crimped around the lead wire and core;

FIG. 5 illustrates the components of the resistor after I the assembly has been c-ut through the middle of the terminal to form two assemblies;

FIG. 6 illustrates the ends of the two assemblies formed illustrating the manner in which the lead wire has been bent back over the terminal;

FIG. 7 illustrates one of the initial steps in a modified method of making the resistance wire wherein the lead wire has been wrapped around the core;

FIG. 8. illustrates the components of the resistor of FIG. 7 after the assembly has been cut through the middle of the wrapped lead wire and through the core to form two assemblies; and

FIG. 9 is a sectional view of a bimetallic terminal stock material which may be substituted for the terminal stock material of FIGS. l6.

The resistor of FIG. l is referred to by the reference numeral 10 while the resistor of FIG. 8 is generally referred to by the reference numeral 11.

Resistor 10 is constructed by feeding an elongated core material 12 of fiber glass or the like having a resistance wire 14 overwound thereon into a machine 16. As seen in FIG. 3, machine 16 includes spaced apart

members

18 and 20. An elongated lead wire material 22 of copper or the like is fed into machine 16 parallel to core material 12 and is spaced therefrom and an elongated strip of terminal stock 24 is fed into machine 16 transversely to core material 12 and lead wire material 22. Core material i12, lead wire material 22 and terminal stock 24 are fed into machine 16 simultaneously and the relationship between these components at this time is illustrated in FIG. 3. Terminal stock 24 may be comprised of a bimetallic terminal stock material 40 such as seen in FIG. 9 if desired. Terminal stock 40 is provided with a brazeable layer 42 comprised of silver solder or the like laminated onto a brass or like layer 44.

The next step in the manufacture of resistor 10 is illustrated in FIG. 4. The terminal stock 24 is cut to the proper length and crimped around the lead wire material 22 and core material 12 by any suitable means. The crimping of terminal stock 24 around lead wire material 22 and core material 12 causes lead wire material 22 and terminal stock 24 to be moved towards core material 12 at a polnt between

members

18 and 20 of machine 16 thereby causing lead wire material 22 to -be bent as illustrated in FIG. 4. If terminal stock 40` is used rather than terminal stock 24, the terminal stock would lbe heated in a secondary operation thereby fusing or brazing layer 42 into intimate contact with the resistance wire.

The next step in the manufacture of resistor is illustrated in FIG. 5. The assembly is cut through the middle of terminal stock 24 transversely to the longitudinal axis of core material 12 by any convenient means thereby forming opposite ends of two resistors 10. Machine 16 would normally be adapted so that the other ends of the two resistors 10 would be terminated simultaneously with the termination of the ends shown and described. FIG. 6 illustrates the manner in which the lead wire material 22 is bent back over the terminals of the two resistors 10.

The completed resistor 10 is shown in FIG. 1 and includes a core 12A overwound with resistance wire 14A. A terminal 24A is provided at one end of resistor 10 and a terminal 24B is provided at the other end of resistor 10. A lead wire 22A is operatively electrically connected to terminal 24A as previously described and includes a U-shaped end portion 26A embracing the interior surface, the inner end and exterior surface of terminal 24A. Lead wire 22A also includes an L-shaped portion 28A which at first extends downwardly and thence outwardly with respect to end portion 26A and terminal 24A as seen in FIG. 1.

Terminal 24B is identical to terminal 24A and for that reason will not be described in detail. A lead wire 22B, identical to lead wire 22A, is electrically connected to terminal 24B as previously described. Resistor 10 may be coated with any suitable material if desired.

With respect to FIGS. 7 and 8, the numeral 30 generally designates a core material overwound with resistance wire 32. A lead wire material 34 is simply wrapped around core 30 as illustrated in FIG. 7. The assembly is then cut through the middle of the wrapped lead wire material (FIG. 8) by any suitable means. The cutting of the assembly results in the opposite ends of two resistors 11 being formed wherein the wrapped lead wire material serves as both a lead wire and a terminal. Normally, the termination of the opposite ends of the two resistors 11 would be accomplished at the same time as the termination of the ends shown in FIG. 8. In FIG. 8, the terminal assembly at the right end of the left resistor 11 is referred to as 34A and the terminal assembly at the left end of the right resistor 11 is referred to as 34B.

The advantages of the resistor 10` are as follows: (1) the invention allows machine processes which do not require core impregnation or some other method of adhering the resistance wire to the core; (2) a double width terminal stock is used which is sliced in two thereby giving two terminations per machine cycle; (3) the slicing operation occurs after termination thus eliminating frayed ends or resistance wire protruding from the terminals; (4) mechanical strength of the resistor is increased because stress imposed on the lead wire acts against the bend thereof and not on the joint; (5) the resistor is economically manufactured since a secondary operation is not required to bond the terminal to the lead wire; and (6) mechanical strength and electrical contact are further improved by use of a fusible or brazeable terminal stock (example: silver solder laminated to |brass), which when heated in a secondary operation provides intimate contact with the reslstance wire.

The advantages of the resistor 11 are as follows: (1)` .4 use of fusable lead wire which when heated in a secondary operation provides intimate contact with the resistance wire. While the resistor has been described as including a resistance wire overwound on a core, a resistor without a resistance wire can be produced by the method described herein. Such resistors would substitute deposited carbon or a metal -film or the like for the resistance wire.

It should be noted that the resistor core can be of any conguration and has been shown to be cylindrical in the drawings for sake of simplicity.

Thus it can be seen that the device and the method of making the same accomplishes at least all of the stated objectives.

Some changes may be made in the construction and arrangement of my resistor without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In a resistor,

a core having opposite ends and a resistance means thereon,

a flat, collar-like terminal means embracing each of the opposite ends of said core and being in electrical contact with said resistance means, each of said terminal means having inner and outer ends and parallel exterior and interior surfaces with respect to said core,

lead wires operatively electrically connected to each of said terminal means,

each of said lead wires having a substantially U-shaped end portion comprising tirst, second and third end portions, said first end portion being positioned between said terminal means and said resistance means and extending inwardly from the outer end of said terminal means, said iirst end portion being parallel to the longitudinal axis of said core and the interior surface of said terminal means, said second end portion extending from the inner end of said first end portion and embracing the inner end of said terminal means, said third end portion extending outwardly from said second end portion and embracing the exterior surface of said terminal means, said third end portion being parallel to said first end portion, said third end portion extending at least outwardly from said terminal means in a parallel relationship to the longitudinal axis of said core.

2. The resistor of claim 1 wherein each of said lead wires have a substantially L-shaped portion extending' from said third end portion of said U-shaped end portion first towards the center of the end of said core and thence extending outwardly therefrom.

3. The resistor of claim 1 wherein said resistance means includes a resistance wire on said core and wherein each of said terminal means are crimped around the core to maintain said resistance wire and the lead wire on said core.

4. The resistor of claim 1 wherein said terminal means includes at least a layer of metallic fusible material at its interior surface, said fusible material being fused to said resistance means.

5. In a resistor,

a core having tirst and second ends,

a resistance means on said core,

a first lead wire operatively secured to said rst end of said core,

a second lead wire operatively secured to said second end of said core,

said rst lead having one end positioned adjacent said first end of said core and having a wrapped portion spirally extending around said core away from said one end of said core, said first lead having its other end extending outwardly from the inner end of said wrapped portion,

5 6 said second lead having one end positioned adjacent 2,055,849 9/ 1936 Mucher 338-332 X said second end of said core and having a wrapped 3,244,953 5/ 1966 Walsh 317-260 portion spirally extending around said core away from said second end of said core, said second lead FOREIGN PATENTS having its other end extending outwardly from the 981,949 1/ 1951 France. inner end of said wrapped portion. 5 1,186,579 2/ 1959 France.

527,735 10/ 1940 Great Britain. References Cited U UNITED STATES PATENTS ELLIOT A. GOLDBERG, Primary Examiner 1,745,939 2/1930 Loewe 338-332 X 10 U.S. C1. X.R. 1,892,202 12/ 1932 Bullinger 338-329 X 338-302, 329