US3395452A

US3395452A - Methods of terminating electrical devices

Info

Publication number: US3395452A
Application number: US459781A
Authority: US
Inventors: Wiley M Hummel
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1963-03-18
Filing date: 1965-05-28
Publication date: 1968-08-06
Anticipated expiration: 1985-08-06

Description

Au 6, 1968 w. M. HUMMEL METHODS OF TERMINATING ELECTRICAL DEVICES Original Filed March 18, 1963' INVENTOR VV/XSy M Hammad fl'tar'neg.

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United States Patent 3,395,452 METHODS OF TERMINATING ELECTRICAL DEVICES Wiley M. Hummel, Prophetstown, Ill., assignor to General Electric Company, a corporation of New York Original application Mar. 18, 1963, Ser. No. 265,665, now Patent No. 3,210,714, dated Oct. 5, 1965. Divided and this application May 28, 1965, Ser. No. 459,781

7 Claims. (Cl. 29-621) ABSTRACT OF THE DISCLOSURE Method for making an electrical connection between a relatively small diameter conductor, forming a coil winding, and a relatively large diameter lead conductor. The lead conductor is wrapped around a support, upon which the coil winding is supported, and then twisted upon itself to firmly grasp the support. The small diameter conductor is then twisted around the lead conductor such that it lies within the valleys formed by the twisting of the large conductor. Subsequent steps may include welding and the application of a clip.

This application is a division of my co-pending application Ser. No. 265,665, filed Mar. 18, 1963, now Patent No. 3,210,714, granted Oct. 5, 1965. The present invention relates to electrical devices such as heating devices, and more particularly to methods for manufacturing and terminating resistance heating devices.

Accordingly, it is an object of my invention to provide a new and improved method for efliciently connecting one end of a wire to a terminal.

A further object of my invention is to provide an improved method for terminating an electrical device.

A still further object of my invention is to provide an improved method for manufacturing an electrical heating device which is economically constructed and eflicient in operation.

In carrying out my invention, in one form thereof I have provided an improved method of manufacturing and terminating a heating device which includes a relatively flat elongated support and a relatively thin heating conductor spirally wound upon the support. Near each end of the support a strip of flexible insulating tape is partially wrapped around some of the end turns of the heating conductor. Each strip of tape also covers a loop in an end portion of the heating conductor, which loop extends longitudinally away from the end turns, and it is partially wrapped around the support itself. A stranded bare conductor relatively thicker than the heating conductor is looped around the strip of tape near each end of the support. The loop of this stranded conductor is disposed transversely to the longitudinal axis of the support and it overlies the longitudinal loop of the heating conductor. A shorter bare end of the stranded conductor is securely wound around an adjacent longer length of the conductor to form a twisted junction that extends transversely to the longitudinal axis of the support. By forming this twisted junction, the stranded conductor is effectively secured to the support, and at the same time, the loop of the heating conductor is held in engagement with the support by the loop of the stranded conductor. With such an arrangement, each bare end of the relatively thin heating wire is wound into mechanical engagement with the twisted junction of an associated stranded and looped conductor. Each twisted junction of the stranded conductor and the heating wire is thereupon welded to provide positive electrical engagement of the two conductors with each other. Such an arrangement provides a simplified and effective means and method for terminating an electrical heater.

Further aspects of my invention will become apparent hereinafter, and the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which I regard as my invention. The invention, however, as to organization and method of utilization, together with further objects and advantages thereof, may best be understood by reference to the following description when taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a perspective view of a mandrel mounted heating device which is to be subsequently terminated in accordance with the present invention;

FIGURE 2 is a fragmentary perspective view of the device of FIGURE 1, after the attachment thereto of a stranded lead which serves as part of a termination for the heating conductor;

FIGURE 3 is a fragmentary perspective view similar to FIGURE 2, and illustrating the mode of attachment of a welding clip to the juncture of the stranded lead and the heating conductor.

FIGURE 4 is a perspective view of a terminated heat ing device, in accordance with my invention; and

FIGURE 5 is a sectional view taken generally along the line 55 of FIGURE 4.

Referring first to FIGURE 1 of the drawing, there is illustrated an electrical heating structure 1 which is mounted on an elongated mandrel 3. The structure 1 generally comprises an elongated tube 5 of insulating material surrounding the mandrel 3 for the major portion thereof, and a heating conductor 7 spirally wound upon the tube 5.

As further shown in FIGURE 1, the mandrel 3 has a flat and rectangular cross section. Tube 5 is constructed of an insulating material such as Teflon, and is in the form of an extruded flat oval shaped sleeve having relatively thin walls which surround the mandrel 3, as shown in FIGURES 1 and 5. The heating conductor 7 comprises a plurality of turns 8 of insulated wire which are precision wound on and supported by the insulating tube 5, as shown in FIGURE 1.

Turning now to a significant aspect of my invention, which concerns a new and improved method for terminating the heating conductor 7, as shown in FIGURE 1 each end portion of the heating conductor 7 is bent over and away from the longitudinal center of the heating conductor, in a direction generally parallel to the longitudinal axis of the mandrel 3. A strip of flexible insulating tape 9, such as for example, fiberglass tape is then pressed initially into engagement with the parallel conductor sections of several of the end turns of the heating conductor 7, and the adjacent portion of the tube 5 so that it covers and positions the bent over longitudinal section 11 of the conductor near its end. The end portion of the conductor 7 is then looped over at 13 and doubled back upon itself by extending a portion 15 back toward the center of the conductor in a direction generally parallel to the longitudinal axis of the mandrel 3. The doubled over portion 15 is then on the outer surface of the beginning part of tape 9. Tape 9 is then wrapped completely around the end turns, and the adjacent part of tube 5 and overlapped upon the doubled over portion 15 of the conductor. Thus, as shown in FIGURE 1, the tape 9 overlaps itself in such a manner that the starting portion of tape 9 is threaded through the loop 13, and the doubled over portion 15 of the conductor wire 7 is arranged between an outer surface of the tape 9 and an overlapped part of the tape 9.

For terminating the stripped ends 7a of the heating conductor 7, as shown in FIGURES 2 and 4, a pair of stranded conductors 17 are utilized. As illustrated in FIGURE 2, conductor 17 is substantially bare, is first looped around tape 9, and is positioned adjacent to a shoulder 21 of tape 9. Shoulder 21 is formed by stretching tape 9 at the end-most turn of the heating conductor 7 (Le, between the end-most turn and the adjacent uncovered surface of the tube 5). T e loop 19 of stranded bare conductor 17 is thus positioned around the taped section of the device (as shown in FIGURE 2) just beyond the last turn of heater conductor 7 and a relatively short end portion 23 of the stranded conductor 17 is thereupon securely twisted around an adjacent portion 25 of the longer length of the stranded conductor 17.

As shown in FIGURE 2, when the shorter end 23 of the stranded conductor 17 is twisted, there is formed a tightly twisted junction 27 of the shorter portion 23 of conductor 17 with the longer portion 25 thereof. By means of the twisted junction 27, the loop 19 is tightly secured around the folded over tape 9. Since the loop 19 of conductor 17 is arranged in transverse relationship to the longitudinal loop of the heater conductor 7, it also compresses the looped end of the heating conductor 7 into engagement with the tube 5. It will thus be understood that by twisting the stranded conductor 17, this conductor has been securely arranged upon the tube 5 and tape 9, and at the same time the looped end of the insulated heating conductor 7 has been additionally secured into compressive engagement with its supporting tube 5.

After the twisted junction 27 has been formed upon the stranded conductor 17, the stripped end 7a of heating conductor 7 is then doubled back again and wound around the twisted junction 27, in the manner illustrated in FIG- URE 2. More particularly, the stripped end 7a of heating conductor 7 is preferably Wound around the twisted junction in the same direction as the direction of twisting of shorter end 23 of conductor 17, and at substantially the same pitch as the twisted junction so that the turns 7b of the stripped end 7a are approximately disposed between adjacent turns 17a of the twisted junction of the conductor 7. It will thus be seen that I have provided a simplified means for facilitating the mechanical connection and cooperation of the conductor 7 of relatively small diameter with a stranded lead 17 of larger diameter.

After the stripped end 7a has been wound into mechanical engagement with the twisted junction 27 of the conductor 17, as suggested by FIGURE 3, a crimping clip 29 is thereupon mechanically crimped into engagement with the twisted junction 27, and the turns 7b of the stripped end 7a of heating conductor 7 (see also FIGURE 4). Preferably, in the illustrated heating device, the clip 29 is placed as close as possible to the tape 9 and engulfs a substantial portion of the twisted junction. As shown in FIGURE 4, the clip 29, the twisted junction 27, and stripped turns 7b of the heating conductor 7 are all then welded together to form a good and positive electrical connection and termination for each end of the heating conductor 7.

While the terminated heating device, as shown in FIG- URE 4, is positioned on a supporting mandrel 3, it will be understood by those skilled in the art, that the mandrel 3 may be readily removed from tube 5, and an elongated bimetallic member (not shown) or some other thermally responsive member may be extended through the tube to provide a thermal timing device.

It will now, therefore, be seen that my new and improved method for manufacturing and terminating electrical devices, as herein illustrated for an electrical resistance heater, are both efiicient and advantageous. In view of the simplified construction of this device and its eflicient mode of termination, it has been found to be very economical to manufacture.

While in accordance with the patent statutes I have described what at present is considered to be the preferred embodiment of my invention it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from my invention, and I, therefore, aim in the following claims to 4 v. cover all such equivalent variations as fall within the true spirit and scope of this invention.

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

1. A method for making an electrical connection comprising the steps of looping an end portion of afirst conductor around a support, twisting an end section of the first conductor around an adjacent section thereof to form a tight loop of the end portion mechanically secured to the support and a twisted junction of bare wire of the end section of the first conductor and the adjacent section, winding the bare end of a second conductor around the twisted junction of the first conductor, and fusing the bare end of the second conductor to the twisted junction of the first conductor.

2. A method for making an electrical connection comprising the steps of looping an end portion of a stranded first conductor around a support, twisting the free end of the first conductor around an adjacent section thereof to form a twisted junction of bare wire of the free end and adjacent section of the first conductor and a tight loop of the end portion mechanically secured to the support, winding the bare end of a second conductor around the twisted junction of the first conductor, and welding the bare end of the second conductor to the twisted junction of the first conductor.

3. A method for making an electrical connection comprising the steps of positioning a looped end portion of a first conductor around a support, twisting the free end of the first conductor around an adjacent section thereof to form a tight loop of the end portion mechanically secured to the support and a twisted junction of bare wire of the free end and adjacent section of the first conductor, and winding the bare end of a second conductor of less diameter than said first conductor around the twisted junction of the first conductor, the second conductor being wound around the first conductor so that at least some of the turns of the second conductor are disposed between adjacent turns of the twisted junction of the first conductor, and fusing the turns of the second conductor to the twisted junction of the first conductor.

4. A method for making an electrical device comprising the steps of winding a first conductor on an elongated support around the longitudinal axis of said support, forming a first loop in an end portion of said first conductor, said first loop extending in a direction generally parallel to the axis of said support and disposed in contiguity thereto, forming a second loop in an end portion of a second conductor, said second loop being arranged in trans verse fashion around said support and traversing said first loop, twisting the free end of the second conductor around an adjacent section thereof to tighten said second loop into mechanical engagement with said support and to compress said first loop of said first conductor into secure engagement with said support, the twisting of the free end of said second conductor forming a twisted junction of bare wire of said second conductor, and winding the bare end of the end portion of said first conductor around the twisted junction of said second conductor.

5. A method for making an electrical device comprising the steps of winding a first conductor on an elongated support around the longitudinal axis of said support, forming a first loop in an end portion of said first conductor, said first loop extending in a direction generally parallel to the axis of said support and disposed in contiguity thereto, forming a second loop in an end portion of a second conductor, said second loop being arranged in transverse fashion around said support and traversing said first loop, twisting the free end of the second conductor around an adjacent section thereof to tighten said second loop into mechanical engagement with said support and to compress said first loop of said first conductor into secure engagement with said support, the twisting of the free end of said second conductor forming a twisted junction of bare wire of said second conductor, winding the bare end of the end portion of said first conductor around the twisted junction of said second conductor, and welding the bare end of said first conductor to the twisted junction of said second conductor.

6. A method for making an electrical device comprising the steps of winding a first conductor on an elongated support around the longitudinal axis of said support, forming a first loop in an end portion of said first conductor, said first loop extending in a direction generally parallel to the axis of said support and disposed in contiguity thereto, forming a second loop in an end portion of a second conductor, said second loop being arranged in transverse fashion around said support and traversing said first loop, twisting the free end of the second conductor around an adjacent section thereof to tighten said second loop into mechanical engagement with said support and to compress said first loop of said first conductor into secure engagement with said support, the twisting of the free end of said second conductor forming a twisted junction of bare wire of said second conductor, winding the bare end of the end portion of said first conductor around the twisted junction of said second conductor, clamping the bare end of said first conductor to said twisted junction adjacent said second loop, and welding the bare end of said first conductor to the twisted junction of said second conductor.

7. A method for making an electrical device comprising the steps of winding a first conductor on an elongated support around the longitudinal axis of said support, forming a first loop in an end portion of said first conductor, said first loop extending in a direction generally parallel to the axis of said support and disposed in contiguity thereto, threading a strip of flexible insulating tape through said first loop and wrapping said strip in overlapped fashion around said loop and at least a portion of said first conductor adjacent said loop, forming a second loop in an end portion of a second conductor, said second loop being arranged in transverse fashion around said support and traversing said first loop, twisting the free end of the second conductor around an adjacent section thereof to tighten said second loop into mechanical engagement with said support and to compress said first loop of said first conductor into secure engagement with said support, the twisting of the free end of said second conductor forming a twisted junction of bare wire of said second conductor, winding the bare end of the end portion of said first conductor around the twisted junction of said second conductor, clamping the bare end of said first conductor to said twisted junction adjacent said second loop, and welding the bare end of said first conductor to the twisted junction of said second conductor.

References Cited UNITED STATES PATENTS CHARLIE T. MOON,

J. CLINE, Assistant Examiner.

Primary Examiner.