US 3494998 A
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Description (OCR text may contain errors)
Feb. 10, 1970 J. w. ANHALT 3, 9
METHOD OF CONNECTOR MANUFACTURING Filed Jan. 27, 1966 do 0 4O INVENTOI Arne/vex;
United States Patent 3,494,998 METHDD 0F CONNECTOR MANUFACTURING John W. Anhalt, La Crescenta, Califi, assignor to International Telephone and Telegraph Corporation, a corporation of Delaware Filed Jan. 27, 1966, Ser. No. 523,401 Int. Cl. B29c 27/30; B29d 3/00 US. Cl. 264-249 3 Claims ABSTRACT OF THE DISCLOSURE A connector member is received fully within an opening formed in a first surface of a plate-like body of thermoplastic material and has connecting portions of reduced dimension extending outwardly from a second surface of the body via an orifice. Heat and pressure are simultaneously applied to the body material immediately adjacent the opening producing an abutment on a shoulder for retaining the connector member Within the thermo' plastic body.
This invention relates to a method of manufacturing electrical connectors and more specifically, to a means for securing a conductor terminal element to a thermoplastic insulator surrounding the element.
In the manufacture of electrical connectors, it is highly desirable that the method employed be inexpensive, accurate, reliable and adaptable to a high degree of automation. A basic step in the fabrication of a connector is that of attaching or joining the insulating element to the conducting element, and a variety of methods have been used. For example, the conductor may be fixed in place as the insulator is molded or otherwise formed, or the insulator may be a multipiece construction employing adhesives or mechanical fasteners for joining the pieces. In both of these approaches the operations involved are costly and require rigid controls for accurate positioning. Accordingly, it is a primary objective of this invention to provide a method for fabricating and assembling an electric connector component which overcomes the foregoing objections and fits the above listed desired requirements.
More specifically, it is an object of this invention to provide an inexpensive thermo-forming method for captivating an electric terminal element such as a terminal pin contact or a pin retaining clip within a thermoplastic insulator.
In accordance with the invention, a thermoplastic insulator is formed with an internal passage which is larger at one end than at an interior point of reduced size. An electric terminal element is inserted into this passage up to a point where its movement is limited by engagement with the reduced portion of the passage. While in this position, an appropriate amount of heat and pressure is applied to the end of the insulator adjacent the passage opening to deform the insulator material surrounding the opening so that a shoulder or abutment is formed in the insulator engaging an end surface of the terminal element. In this simple fashion, the shoulder when cooled prevents the element from being withdrawn from the passage. If necessary, a suitable mandrel may be inserted within the passage to support the insulator material and the terminal element during the deforming operation.
Further features, objects and attendant advantages will become apparent with reference to the following drawing in which:
FIG. 1 is a cross-sectional view of a completed connector made in accordance with the invention;
FIG. 2 is a cross-sectional elevational view of the thermoplastic insulator for the electrical connector;
FIG. 3 shows the insulator of FIG. 2 with an electrical contact retaining clip positioned within the insulator; and
3,494,998 Patented Feb. 10, 1970 FIG. 4 shows the elements of FIG. 3 during the captivating operation of the invention.
Connector terminal contacts are normally either fixed or removably secured to the supporting insulator. In the example of the invention illustrated, the contact is of the removable type as shown in FIG. 1, wherein an insulator 10 supports a contact retaining clip 16 which receives a terminal contact pin assembly 22. The assembly includes a forwardly projecting pin portion 24 secured to a collar 26 and tubular portion 28 secured to a conductor 30. As can be seen, the pin assembly is inserted into the clip 16 and inwardly extending resilient tongues 32 engage collar 26 to prevent withdrawal of the assembly.
If the assembly is to be removed, a suitable tool may be inserted to depress the tongues 32. For further details regarding this type of removable pin contact connector, reference is made to US. Patent 3,158,424 by Roger Bowen, assigned to the same assignee as the present invention.
The present invention relates to an improved means for securing the contact retaining clip 16 to the insulator 10 or for securing a contact assembly directly if not of the removable type. Turning now to the steps of the method, the one piece insulator 10 shown in FIG. 2 may be molded or otherwise formed with an internal passage 12 extending from one end 10A of the insulator to its opposite end 10B. The passage is provided with a first section 12A having a cylindrical shape and a second section 12B having a diameter smaller or reduced from that of section 12A. A shoulder 14 divides the diameter change between the two sections.
The contact retaining clip 16 has a cylindrical shape which conforms to the side walls of the section 12A. As can be seen from FIG. 3, the clip may be inserted into the conductor passage through insulator end 10A until one end of the clip engages the shoulder 14. In that fully inserted position, the opposite end of the clip is spaced slightly inwardly from insulator end 10A.
In accordance with the invention, an arbor or mandrel 18 having a first portion 18A which conforms to the diameter of passage section 12B and a second portion 188 having a diameter which conforms to the interior of clip 16, is inserted into the passage and clip.
The shoulder 14 engaging the end of arbor section 18B limits the inward movement of the arbor. A suitable fixture 20 including a heating coil 22 is placed against the end 10A of the insulator and the outer end of the arbor. It should be understood that the arbor can be formed integral with the fixture 20 if desired. By energizing the coil 22, heat is applied to the insulator end surface and simultaneously, suitable pressure is applied to the end of the fixture 20 and transmitted to the insulator.
The combination of this heat and pressure causes the tensile strength of the thermoplastic adjacent the end of the insulator to be exceeded and permanent deformation occurs. The heat in addition to lowering the tensile yield of the plastic, which permits deformation at lower pressure, also removes residual stresses from the plastic which action stabilizes the material and prevents recurring residual movement when reheated. The heat and pressure cause the insulator material to flow into the space at the end of clip 16 adjacent the mandrel 18 to form an abu ment 34. When the deformation is complete, the fixture 20 and mandrel 18 are removed; and as the insulator plastic cools the abutment 34 hardens to prevent the clip from being withdrawn. In this fashion the retaining clip is uniquely and simply secured to the insulator.
It will be understood that the appropriate heat level and pressure is to be selected to properly deform the particular thermoplastic utilized. In a preferred arrangement, an acetal resin has been used as the thermoplastic and it has been raised to a temperature level of 350 to 400 F. and subjected to a pressure of approximately 10,000 pounds. Other appropriate thermoplastics such as nylon, polycarbonate and glass filled nylon may also be employed.
It will be appreciated that the above described connector terminal forming technique simplifies and eliminates most of the costly processes usually involved in the cap tivation of contacts or contact clip retainers and lends itself well to complete automation. Electrical integrity of the insulator is greatly increased by its one piece construction and contact retention values far exceed usual requirements. The significance of this improved technique may be more easily appreciated when it is realized that a single connector component typically includes a large number of individual contacts or contact retaining clips captivated in a single insulator. With such component, all of the conductors may be captivated in the insulator in a single operation in accordance with the technique of the invention by employing a suitable fixture incorporating the appropriate number of arbors in connection with the heating and pressurizing means.
What I claim is:
1. A method of manufacturing an electrical connector component comprising the steps of providing a thermoplastic insulator having a forward face and flat rear face; forming a passage in said insulator having a first cylindrical section opening at said forward face and a second elongated coaxial cylindrical section opening at said rear face defining between said sections a radially extending shoulder; providing a generally cylindrical contact retaining clip which conforms to but is shorter than said second passage section and embodies at least one forwardly and radially inwardly extending spring tang;
inserting said clip into said second passage section until the forward edge thereof abuts said shoulder so that the rear edge of said clip is spaced axially from said rear face of said insulator;
inserting into the clip a cylindrical mandrel that conforms to the inner cylindrical wall of said clip so as to provide an annular space defined by said rear edge of said clip, the wall of said second passage section and the surface of said mandrel, and open at said rear face of said insulator;
applying sufiicient heat and pressure against the portion of said rear face of said insulator surrounding said second passage section to cause insulator material to flow radially inwardly and substantially fill said annular space, whereby said material when cooled provides an annular abutment that prevents said clip from being withdrawn from said second passage section; and
withdrawing said mandrel from the interior of said clip.
2. The method as set forth in claim 1 wherein said heat and pressure is applied to said insulator by urging a heated surface against said portion of said rear face so as to close said annular space.
3. The method as set forth in claim 1 wherein said heat and pressure is applied to said insulator by providing a heated fixture including said mandrel and a rearwardly disposed radially outwardly extending surface, inserting said mandrel into said clip a sufiicient distance to close said annular space by said surface, and urging said surface against the rear face of said insulator.
References Cited UNITED STATES PATENTS 2,120,630 6/1938 Seever 264-271 X FOREIGN PATENTS 85,563 5/1958 Denmark.
ROBERT F. WHITE, Primary Examiner T. J. CARVIS, Assistant Examiner US. Cl. X.R.