US 2873434 A
Description (OCR text may contain errors)
Feb. 10, 1959 R. F. DRUM ET AL INSULATION PIERC ING TERMINAL Filed Dec. 31, 1954 I 2,873,434 INSULATION PIERCING TERMINAL Raymond F. Drum, Choconut, Pa., and Leslie A. Weun,
Binghamton, N. Y., assignors to International Business I Machines Corporation, New York, N. Y., a corporation of New York Application December 31, 1954, Serial No. 479,117
2 Claims. (Cl. 339-97 This invention relates to terminal elements for electrical conductors and more particularly to an improved terminal element construction and to an improved method of securing terminal elements to insulated electrical conductors.
The fabrication of complicated electrical circuits into component units has been greatly facilitated by the use of terminal elements securable to the ends of insulated electrical conductors. Recent years have seen an increase in use of terminal elements particularly of the type wherein the insulation covering a conductor is pierced by suitable points formed integral with the terminal element as the same is deformed into engagement with the conductor. Such piercing type of terminal element, although providing for ease of assembly and consequent decrease of fabrication expense, requires the utilization of special dies for forming the same and oftentimes results in a terminal element connection that fails to provide the desired extent of electrical contact area and mechanical strength in the assembled unit.
This invention may be briefly described as. an improved terminal element construction and method for securing terminal elements to insulated electrical conductors wherein insertion of the insulated conductor into the terminal element results in a partial, though extensive, stripping of the insulation therefrom for increased area of electrical contact, and subsequent deformation of the terminal element results in a joint of improved electrical and mechanical properties and characteristics.
The object of this invention is the provision of an improved terminal element construction for insulated electrical conductors and a method for obtaining the same.
Other objects and advantages of the invention will be pointed out in the following disclosure and claims and will be illustrated in the accompanying drawings which describe, by way of example, the principles of the invention and the presently preferred embodiments of the terminal element construction incorporating those principles.
Referring to the drawings:
Fig. 1 is a plan view of a blank for the terminal element preparatory to the forming thereof;
Fig. 2 is a plan view of the blank of Fig. 1 after it has been preliminarily formed to receive an insulated conductor;
Fig. 3 is an end elevation of the terminal'illustrated in Fig. 2; and
Fig. 4 is a sectional view of the terminal after it has been deformed into engagement with and around an insulation covered electrical conductor.
Referring to the drawings and particularly to Fig. 1, there is provided a terminal blank having a connector portion generally designated 11 and a conductor engaging portion generally designated 12. The connector portion 11 after deformation thereof is adapted to be soldered or otherwise connected to a terminal strip or like article and therefore may have any desired configuration in accordance with the dictates of the ultimate connection to be effected. The conductor-engaging portion 12 is provided with a peripheral wing portion 13 and a secondary wing 2,87 3,434 Patented Feb. to, 1959 Ice 2 portion disposed within said indicated at 14.
Figs. 2 and 3 illustrate the requisite preliminary shaping of the blank into a configuration adapted to receive the peripheral wing portion as insulated conductorspreparatory to the actual mounting of the terminal thereon. As there illustrated, the peripheral wing portions 13 are bent substantially into a U shape as illustrated at 15, and the secondary wing portions 14 are bent substantiallyinto a U shape of appreciably shorter radius than that of the peripheral wing portions as best illustrated 'at16. Because of the shorter radius of curvature of the secondary wing portions 14, both of the ends thereof 17 extend somewhat abovethe corresponding opening 18in the peripheral wing portion 13 from which they were blanked and provide a relatively sharp, inwardly disposed edge 19*asa r'esult of the degree of bend to which they were subjected.
The preformed terminaleleinent as illustrated in Figs. 2 and 3 is attached to the end of an insulated conductor by first inserting the end "portion at the conductor downwardly into the substantially U-shaped portion of the terminal element defined by. the deformed secondary wing portions 14. The spacing intermediate the arms of the substantially U-shaped portion defined by the secondary wing portions 14 should be such as to effect a removal of the side portions of the insulated covering on the conductor as the same is moved downwardly past the edge 19 of the end portions 17 thereof. The stripping of the side portions of the insulation from the conductor results in the exposing of a relatively large area of the conducting material, which area, upon further depression into the unit, is then disposed immediately adjacent to and in intimate contact with the arms of the U-shaped secondary wing portions 14.
After insertion of the conductor with the consequent removal of the side portions of the insulation therefrom as described above, the arms 17 of the secondary wing portions 14 are bent around the wire as illustrated at 20 in Fig.4. Simultaneously therewith the peripheral wing portions 13 are clamped around the secondary wing portions so that its sides overlap the latter as illustrated at 21 in Fig. 4.
Due to the requisite and necessary removal of the side portions of the insulation on the insulated conductor effected during insertion of the conductor into the unit, the spacing of the arms 17 of the secondary wing portions 14 is somewhat critical and must necessarily vary. in accordance with the size of the insulated conductor being utilized. The following dimensions relating to the capital letters on the drawings have been found in practice to be satisfactory in effecting the desired removal of the s ide portions of the insulation on the conductors: for #20 wire size for a terminal constructed in accordance with the principles of this invention: A-.025 inch; B-.1l0 inch; C.020 inch; D-.235 inch; and E.040 inch.
The advantages obtainable through the above terminal construction and method of forming the same are a re sultant terminal having greater electrical contact area, greater mechanical strength, and the elimination of dies of special configuration as conventionally required for the present-day piercing type of terminal construction.
The principles of the invention have been described and illustrated in a single operative unit for the purpose of teaching those skilled in the art how the invention may be performed. Certain changes in configuration will appear to those skilled in the art, and it is contemplated that such changes may be employed but yet fall within the spirit and scope of the invention insofar as they are within the claims that are to follow.
Having thus described our invention we claim:
1. A solderless terminal for insulated electrical conductors comprising a plurality of integral conductoramass-4 3 r pp n p i n a f rela ely .risis e deforma substantially U-shaped cross section with'common base portions; one of said portions having parallel conductorgripping arms of substantially shorter-longitudinal and arm lengths than, and being symmetrically positioned within, the, arms of the other portion and being provided with elongated relatively blunt parallel ends spaced by a ,value substantially equal to theconductor transverse dimension to strip sections of the insulation from and bare the side portions of an insulation covered electrical conductor forceably inserted between the arms of said one portion; and said arms -o f said other portion being spaced by the insulated conductor transverse dimension'to guide an insulated conductor symmetrically into said one pair of arms during said insertion thereof,
A c ps d r es te m na s ferv susla ec CQnducor -c p a n tar condu t v -memberh y gn s f b a all ,U \-S P s .zq osssec ena po ions. "p 70- viding ir o aims nen r. of aid. arm ingra a and relatively rigidandipositioned to, be upstanding in y t ca re a ons ithin -.an .th p i ofv s i fir but having shorter arrn and longitudinal lengths: thannsaid' other pair of said arms and having relativelytbluntarmcompassing engagement thereof with the insulationstripped areas of said conductor and crimped overlying encompassing engagement of said other pair of arms with at least the crimped ends of said one pair of arms and with longitudinal sections of the insulated conductor located on each side of said one pair of arms;
References Cited in the file of this patent UNITED STATES PATENTS 1,608,578 Buckenberg p Nov. 30,1926 2,501,187 Oortgijsen Mar. 21 1950 2,501,870 Malhoit Mar. gs, 1 950 2,518,489 Orlando Aug. '15, 1950 2,680,235 Pierce Junel, 1954