US3696322A

US3696322A - Insulated flat wire terminal

Info

Publication number: US3696322A
Application number: US41789A
Authority: US
Inventors: Paul J Spangler; Thomas E Morgan
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1970-06-01
Filing date: 1970-06-01
Publication date: 1972-10-03
Anticipated expiration: 1989-10-03
Also published as: CA979506A; FR2095734A5

Abstract

Before crimping, a flat wire connector has a cross-section which is somewhat U-shaped with upstanding side plates having serrations on the top and a rosette of upstanding tines in the floor. When the connector is crimped, the flat wire is pressed down over the rosette, the tines of which pierce the insulation. The two upstanding side walls are rolled in toward the middle of the U, and the serrations are driven downwardly to pierce the insulation and stake the flat wire. The length of the side walls is such that the flat wire may be badly out of alignment with respect to the connector and yet insure a good electrical connection.

Description

United States Patent Spangler et al.

[451 Oct. 3, 1972 [54] INSULATED FLAT WIRE TERMINAL [73] Assignee: International Telephone and Telegraph Corporation, New York, NY.

[22] Filed: June 1, 1970 [21] Appl. No.: 41,789

[52] US. Cl. ..339/97 C, 339/223 R [51] Int. Cl. .1101! 11/20 [58] Field of Search ..339/95, 97-99, 339/223, 276

[56] I References Cited UNITED STATES PATENTS 3,335,392 8/1967 Elliott ..339/97 C 2,515,105 7/1950 Weisberg ..339/97 C 2,943,293 6/1960' Bucher et al ..339/223 R 3,388,367 6/1968 Brown ..339/97 P 3,395,381 7/1968 I-Iuffnagle ..339/97 C 2,302,767 11/1942 I-Iackbarth ..339/97 C FOREIGN PATENTS OR APPLICATIONS 617,955 11/1926 France ..339/97 C Primary Examiner-Joseph I-I. McGlynn Attorney-C. Cornell Remsen, Jr., Walter J. Baum, Percy P. Lantzy, J. Warren Whitesel, Delbert P. Warner and James B. Raden ABSTRACT Before crimping, a flat wire connector has a cross-section which is somewhat U-shaped with upstanding side plates having serrations on the top and a rosette of upstanding tines in the floor. When the connector is crimped, the flat wire is pressed down over the rosette, the tines of which pierce the insulation. The two upstanding side walls are rolled in toward the middle of the U, and the serrations are driven downwardly to pierce the insulation and stake the flat wire. The length of the side walls is such that the flat wire may be badly out of alignment with respect to the connector and yet insure a good electrical connection.

8 Claims, 12 Drawing Figures PATENTEDnms I972 3.696.322

SHEET 1 OF 3 I VEXT 5 THOMAS E. M0964 Y P401. SPA/V645,?

AT TORNEY INSULATED FLAT WIRE TERMINAL This invention relates to terminals for crimping onto the end of insulated wires and more particularly to terminals for crimping onto the ends of insulated flat wires.

Flat wires are relatively. new types of insulated electrical conductors. The conductor itself is somewhat reminiscent of Christmas tree tinsel. Without being overly precise, the tinsel is a strip of foil (usually copper) which is about one-thirty-second to one-sixthfourth of an inch wide and about as thick as tissue paper. The foil is embedded in or surrounded by an insulating material which is almost impossible to strip off the foil. Even if it were possible to strip the insulation from the foil, the resultant exposed foil conductor would be too weak to support itself. It could not withstand any kind of strain which might occur in even the most carefully guarded environment.

Accordingly, an object of this invention is to provide new and improved crimped connectors for attachment to insulated wires and more particularly to connectors for insulated flat wires.

Yet another object is to provide connectors which pierce insulation and make connection with very fragile wires. In this connection, an object is to provide connectors which do not weaken extremely fragile conductors. In particular, an object is to provide a connector which utilizes the strength of the insulation material to establish resting maintain a strong mechanical bond. Stated another way, an object is to provide a strong mechanical bond and a good electrical connection to a tinsel wire. Stated still another way, an object is to provide the described type of connector which is free of virtually all mechanical stresses.

In keeping with an aspect of this invention, these and other objects of the invention are accomplished by a flat wire connector stamped from a ribbon of contact metal. Before crimping, the cross-section of the connector is somewhat U-shaped, a rosette of upstanding tines in the floor of the connector U. The upstanding side plates of the U-shaped section have serrations on their top. When the connector is crimped, the flat wire is pressed down over the rosette, the tines of which pierce the insulation. The two side walls are rolled in toward the middle of the U, and the serrations are driven down to pierce the insulation and stake the wire. As the side walls are driven down, they mushroom the rosette tines and apply a substantial connector force, which insures a good connection. The length of the side walls is such that the flat wire may be badly out of alignment with respect to the connector and yet insure a good connection.

The above mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an inventive connector with a flat wire poised above an open U-shaped connector;

FIG. 2 is a plan view looking down on top of the connector of FIG. 1;

FIG. 3 shows a side elevation view of the connector taken along line 33 of FIG. 2;

FIG. 4 is a back elevation view of a connector taken along line 4-4 of FIG. 2;

FIG. 5 is an elevation view of the back end of the connector (taken along line 4-4) after crimping;

FIG. 6 is an elevation view of the front end of the connector (taken along line 6-6) after crimping;

FIG. 7 shows a perspective view of a confined die for crimping the inventive connector;

FIGS. 8A-8D includes four stop motion views which are four successive steps in the crimping process; and

FIG. 9 is a perspective view of a crimped connector with the side walls broken away to show the mushroomed rosette of tines.

After manufacture and before crimping, the original form of the connector 20 includes a forked spade terminal 21 and a ferrule 22 having an initially U-shaped cross-section.

The flat wire comprises a very thin tinsel-like foil 36 (preferably of copper) embedded in a plastic coating 37 which completely surrounds and protects the foil on all of its sides.

The

ferrule side walls

23, 24 of the U-shape are serrated along the top edge for a substantial length L. The

rear parts

25, 26 of the side walls are not serrated to provide gripping ears which fold over to hold the flat wires and provide strain relief. The rear most edges 28-30 of the ferrule are chamfered, rounded, or otherwise shaped to prevent the wire from bending over a sharp angle. Thus, the

parts

25, 26 hold the wire against withdrawal, and the rounded edges 28-30 allow the wire to wrap around a radius and thereby distribute fatiguing forces.

A rosette 31 of upstanding tines is in the floor of the ferrule part 22 of the connector 20. Each tine has a sharp point with the mechanical strength required to pierce a flat wire. Preferably, the rosette is positioned to mushroom over the top of the flat wire, and apply a contact pressure which is adequate to give good electrical contact at the connection between the flat wire and the connector, throughout the life time of the terminal.

While many materials may meet the required connector specifications, I prefer to use a 7% hard cartridge brass. The flat wire is a standard commercial product.

The crimping tool, die, and process are seen in FIGS. 7 and 8. This tool and die makes a crimp known in the art as an F-crimp. One-half of the crimping tool is an indenter 41 (FIG. 7) having a top surface 42 which conforms to the shape of the lower side of the crimp. The other half of the crimping tool is a nest 43 having a pair of generally

semi-circular surfaces

44, 45 conforming to the shape of the upper side of the crimp. Roughly speaking, the indenter top surface 42 is somewhat U- shaped, with a rather flat bottom section. The nest 43 has a somewhat M-shape, rounded to guide and direct the side walls, 23, 24 of the connector so that they roll inwardly toward the center of the crimp as the punch is lowered into the die. The nest for crimping the rear parts of the terminal (25 and 26) should not be M- shaped but should have a generally flat bottom.

The flat wire is positioned in the bottom of the U- shaped ferrule and over the rosette of tines. Thereafter, the ferrule 22 is placed in the confined die 42. The

4 manner in which the crimping occurs may be seen in the successive stop motion views of FIGS. 8A-8D. First, (FIG. 8A), the connector 20 is placed on the indenter 42 with the bottom of the connector resting against the bottom of the die 42.

Then, (FIG. 8B) the nest 43 is lowered into the die 42 with a force F. As the punch 43 goes downward, the outside edges of the

punch areas

44, 45 come into contact with the

side walls

23, 24 of the connector. The

sides

23, 24 begin to roll over as they are guided.

flat wires in the bottom floor of the indenter 42..The

upstanding tines in rosette 31 are forced through the flat wire. The force of the serrated edgesdriving into the insulation tend to mushroom the rosette tines and bend them over toward the floor of the connector ferrule.

Finally, as the nest 43 is moved to the extremity of its stroke, the

side walls

23, 24 are closed into their fully crimped position (FIG. 8D). The serrations are driven through the insulation and into the conductive foil 36. Thereafter, the nest 43 is raised, and the completed connector-flat-wire crimped unit is removed from the indenter 42.

FIG. 9 is a perspective view of the crimped connector with the

side walls

23, 24 broken away to show the rosette tines 31 which have pierced the fiat wire 35 and mushroomed over. As the crimping forces are removed when the nest 43 is raised, there might be some minor relaxation of the connector material. However, the double reiliability of the mushroomed tines 31. driven downwardly under the force of the rolled serrated edges provides a contact pressure which is more than adequate to maintain a good electrical connection throughout thelifetime of the crimp.

Other modifications will readily occur to those who are skilled in the art after they have read the foregoing specification and studied the attached drawings. For example, instead of the rosette 31, a number of louver like tines may be sequentially placed in the floor of the connector. Or a pair of tines may be positioned to project upwardly and crimp over, somewhat as a paper staple is crimped. Still other rivet-like connections may be provided.

Normally, it is much less expensive and more desirable to make the entire crimp in a single step. However, there may be occasions when it is more reliable to perform the crimping operation in two steps. First, the rosette or other tines are crimped, as with a paper stapler or a rivet. Then, the serrated side walls,are rolled in toward the center. These two steps may be performed by a two part nest and single indenter. First,

one part of the nest moves in to crimp the rosette tines,

and then it retracts. Thereafter, the nest 43 rnoves in to roll the sides. This two-step operation can be done in a single stroke.

While the principles of the invention have been described above in connection with specific crimp and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

We claim:

1. A flat wire connector comprising a terminal member and an integral ferrule member, said ferrule being U-shaped in cross-section having upstanding side walls connected by a fl r section the top edges of said side walls being serrate along at least a partial length,

said serrations extending longitudinally from a position adjacent said terminal, said ferrule including a non-serrated gripping portionextending from a position adjacent the opposite end of said ferrule and along the top edges of said side walls, said gripping portion terminating in an outwardly extending edge portion having an outwardly decreasing cross-sectional thickness for relieving mechanical fatigue atthe point where said flat wire enters said connector.

2. The flat wire connector of claim 1 and means for physically separating said serrated edges and said gripping portion to provide separate ferrule parts having independent mechanical gripping and electrical contact making functions.

3. The connector of claim 1 and a rosette of upstanding sharp pointed tines in the floor of said U-shaped section, said rosette of tines being positioned to pierce a flat wire positioned in said U-shaped section when said ferrule is crimped.

4. The connector of claim 1 and means for rolling the side wall portion with serrated edges to curl over toward the center of the U shaped section and pierce the insulation of a flat wire in the bottom of said U- shape.

5. The connector of claim 4 and at least one upstanding tine in the floor of said U-shaped section, said upstanding tine being positioned under the serrations of said side walls when in said rolled position whereby the driving of said serrations into said insulation during a crimping operation tends to crimp the top of the upstanding tine.

6. A flat wire connector, comprising a ferrule portion having somewhat U-shaped cross-section with serrations extending longitudinally along a first section on the tops of the side walls of the U-shaped cross-section and at least one upstanding sharp pointed tine in the bottom of the- U-shaped cross-section, said side walls rolling over during crimping to drive said serrations and said tine through said flatwire, and having chamfered means at the end of said ferrule for relieving mechanical fatigue at the point where said flat wire enters said connector.

7. The connector of claim 6 and means comprising the tine at the bottom of the U-shape for riveting or stapling the flat wire to the bottom of the connector.

8. The connector of claim 7 and gripping ears formed in said walls for holding said flat wire in mechanical connection with said connector.

Claims

1. A flat wire connector comprising a terminal member and an integral ferrule member, said ferrule being U-shaped in crosssection having upstanding side walls connected by a floor section, the top edges of said side walls being serrated along at least a partial length, said serrations extending longitudinally from a position adjacent said terminal, said ferrule including a non-serrated gripping portion extending from a position adjacent the opposite end of said ferrule and along the top edges of said side walls, said gripping portion terminating in an outwardly extending edge portion having an outwardly decreasing crosssectional thickness for relieving mechanical fatigue at the point where said flat wire enters said connector.

4. The connector of claim 1 and means for rolling the side wall portion with serrated edges to curl over toward the center of the U-shaped section and pierce the insulation of a flat wire in the bottom of said U-shape.

6. A flat wire connector comprising a ferrule portion having somewhat U-shaped cross-section with serrations extending longitudinally along a first section on the tops of the side walls of the U-shaped cross-section and at least one upstanding sharp pointed tine in the bottom of the U-shaped cross-section, said side walls rolling over during crimping to drive said serrations and said tine through said flat wire, and having chamfered means at the end of said ferrule for relieving mechanical fatigue at the point where said flat wire enters said connector.