1. Field of the Invention
The invention relates to an electrical connector. More particularly the invention relates to a lightweight and cost efficient electrical connector assembly with significant material and manufacturing efficiencies realized by application of multi-shot injection molding technology.
2. Description of Related Art
Electrical connectors are typically manufactured via precision machining of a plurality of metal and dielectric elements that are then assembled to form the connector assembly.
Machining of metal elements from metal bar stock typically results in significant material waste and requires sophisticated high precision machining/turning equipment and skilled operators for same.
A previous application of polymeric materials to a coaxial connector for use with helical corrugated solid outer conductor coaxial cable is disclosed in U.S. Pat. No. 5,354,217, issued Oct. 11, 1994 to Gabel et al. Polymeric materials are applied to both the connector body and a clamp nut, requiring multiple machined internal conductive elements to form a conductive path for the outer conductor across the connector. However, the separate metal and polymeric elements must each be separately formed, any flashing removed or other rework performed and each of the separate elements assembled together by labor intensive press fit and/or hand assembly operations to complete the connector assembly. Manufacture, quality control, inventory and delivery coordination to the assembly area of each of the plurality of separate elements is a significant additional manufacturing cost. Further, a problem resulting in a delivery delay of any one of the multiple separate elements and or damage or loss during field assembly renders the remainder of the connector inoperable.
In U.S. Pat. No. 5,354,217, the clamp nut threads upon helical corrugations of the outer conductor and the leading edge of the outer conductor is then manually precision-flared against the clamp nut prior to connector assembly. Therefore, the connector is incompatible with smooth or annular corrugated solid outer conductor coaxial cable, is expensive to manufacture and time consuming to install.
Electrical connectors interconnecting RF equipment such as antennas may include multiple conductors and/or connectors. Each of the connectors may be mounted to a base, backplane, enclosure or other flange surface of the antenna as a communications, power and/or control electrical cable interconnection. The mounting of the connectors upon holes formed in the base or other flange may require tool access to both sides of the mounting point, creating an overall increase in the antenna size, complicating assembly and/or introducing additional environmental sealing issues.
Competition within the cable and connector industry has increased the importance of minimizing connector weight, installation time, materials waste, overall number of discrete connector parts and connector manufacturing/materials costs. Also, competition has focused attention upon ease of use, electrical interconnection quality and connector reliability.
Therefore, it is an object of the invention to provide an electrical connector and method of manufacture that overcomes deficiencies in such prior art.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. Like reference numbers in the drawing figures refer to the same feature or element and may not be described in detail for every drawing figure in which they appear.
The inventor has recognized that injection moldable metal compositions, usable with conventional polymeric injection molding equipment, enables manufacture of multi-shot combination metal and polymeric material electrical connector assemblies. Thereby, numerous manufacturing steps and the prior need for additional seals between separate elements may be eliminated to realize a significant materials and manufacturing cost savings.
An example of an injection moldable metal composition is “Xyloy”™ M950 available from Cool Poly, Inc. of Warwick, R.I., US. “Xyloy”™ M950 comprises an aluminum and zinc composition delivered in pellet form to injection molding equipment in the same manner as raw polymer pellets. Because the melting point of zinc is comparatively low, a combination of aluminum and zinc results in an alloy with a low enough melting point and viscosity characteristics suitable for use in polymeric injection molding machines without requiring any modification thereto. Other suitable injection moldable metal compositions preferably have melting points and viscosity characteristics that similarly enable use of conventional polymeric injection molding equipment with maximum operating temperatures around 1100 degrees Fahrenheit. Injection moldable metal compositions as described herein above do not require specialized metal injection molding “MIM” equipment, which relies upon application of higher temperatures and/or pressure incompatible with traditional injection moldable polymers to fluidize a metal alloy, such as thixotropic magnesium alloy(s).
In the exemplary embodiments demonstrated in
To minimize metal material costs and the overall weight of the connector, a metal inner body 17 is provided as an outer conductor conductive path between the annular ramp surface 9 and the connection interface 19. A polymeric outer body 21 surrounds the inner body 17 and may include, for example, tool flats 23 for use during connector assembly and or mating threads 25 for the coupling body 3.
The slip ring 5 spring mating surface 27 with the clamp spring 11 may be formed of metal, to avoid polymeric material creep that may occur over time which could prevent easy separation of the clamp spring 11 from the split ring 5 when removed, for example, for periodic inspections of the cable and connector interconnection. A cylindrical slip ring body 29 that maintains coaxial alignment of the slip ring 5 with the coaxial cable may be formed from polymeric material.
Because it is outside of the electrical path, the coupling body 3 may be formed entirely from polymeric material.
Environmental sealing of the connector may be improved by applying environmental seal(s) 31 such as gasket(s) and/or o-rings between the outer conductor and the connector, for example positioned between the slip ring 5 and the coupling body 3 and/or between the connector body 7 and the coupling body 3. A further sheath seal 33, sealing between the coupling body 3 and an outer sheath of the cable may be formed in place upon an outer surface of the coupling body 3 bore 1, for example molded into an annular groove 35. Compared to a conventional o-ring type seal inserted into an annular groove 35, an environmental seal formed in place has a significantly reduced chance for failure and/or assembly omission/error, as the potential leak path between the o-ring and the annular groove 35 and the potential for o-ring slippage out of the annular groove 35 is eliminated.
Although the inner contact 13 may be similarly manufactured by molding, a conventionally machined inner contact 13 is preferred to enable use of beryllium copper and or phosphor bronze alloys with suitable mechanical characteristics for spring finger and/or spring basket 37 features of the inner contact 13 that receive and retain the inner conductor of the cable and/or of the inner conductor mating portions of the mating connector at the connection interface 19.
As used herein, multi-shot injection molding is understood to be an injection molding manufacturing procedure wherein additional layers are injection molded upon a base element and/or prior injection molded layers. Preferably, the portion undergoing molding need not be fully released from the mold. Instead, the portion may be retained aligned within the mold nest and only portions of the mold as required to define a further cavity to be injection molded with material are reconfigured. The resulting element is permanently integrated without any mechanical coupling mechanisms, fasteners or assembly requirements. By changing the injection material between metal, dielectric polymer and structural polymers an integral connector element is obtained that is fully assembled upon application of the last layer.
In an exemplary method for manufacturing the connector body 7 via multi-shot injection molding, a mold for the conductive sleeve is injected with the injection moldable metal composition, forming the inner body 17 conductive sleeve. An inner portion of the mold is removed and the inner contact 13 positioned therein as shown for example in
A space between the inner contact 13 and the inner body 17 is then injected with a dielectric polymer to form the dielectric insulator 15 in-situ as shown in
The order of molding is preferably arranged based upon the melting point of the various materials applied with the injection moldable metal composition typically being first, the dielectric polymer second and the outer body 21 polymer last.
The slip ring mating surface 27, as shown in
The coupling body 3, as shown in
Thereby, the connector is formed in only three main elements that are easily assembled with the desired environmental seal(s) 31, clamp spring 11 and any further connection interface 19 portions to form the connector.
As shown in
Connector layer interlocking may be applied to ensure that the various layers of the connector remain interlocked, for example as significant rotational and/or axial forces are applied during connector to cable and/or connector to connector assembly. Although the direct molding of the layers upon one another and/or shrinkage characteristic differentials of the selected materials may provide a significant layer interlock, further interlocking may be applied via application of interlock feature(s) 47, for example as groove(s) 49 and/or ridges on the inner contact 13 and/or the inner diameter of the inner body 17.
To take advantage of shrinkage characteristic differentials between materials during molding, for example between the dielectric insulator 15 and the inner body 17, the interlock feature 47 may be provided, for example, as a groove 49 of the inner body 17 that mates with a lip 51 of the dielectric insulator 15, as best shown in
Further interlock feature(s) 47 may be applied as protrusion(s) 53 for improved rotational interlock. Where the protrusion(s) 53 are positioned proximate a mold break point 54, protrusion(s) 53 that would require significant additional machining in a conventional connector manufacture procedure may be easily applied.
Connector layer interlocking between the dielectric insulator 15 and the inner contact 13 may be applied, for example, as shoulder(s) 55 between which the dielectric insulator 15 is molded for axial interlocking and as axial rib(s) 57 for rotational interlocking.
Improved polymer thickness uniformity may reduce a required set time for the, for example, outer body 21 polymer molding step by minimizing areas of greater than average polymer thickness within the element. Thereby, polymer material requirements and the overall weight of the coaxial connector may be reduced. A primary area of increased material thickness in the outer body 21 is located proximate the tool flat(s) 23. By forming the tool flat(s) 23 with material reduction groove(s) 59 polymer material thickness with respect to the closest external surface may be significantly reduced.
The relatively soft polymer material tool flat(s) 23 of a connector may be damaged by application of wrenches of incorrect size and/or inadequate precision. As best shown in
In further embodiments, the connector inner body 17 and/or outer body 21 may be applied as a larger structure which has further utility such as providing a single inner body 17 and/or outer body 21 utilized by multiple connectors.
As shown in
The inner body 17 of the multi-connector assembly 61 may be multi-shot injection molded of metal alloy in an initial molding step with mold portions forming the respective male 73 and female bores 69, best shown in
With the male and female pins 87 and 81 suspended by the mold elements within their respective male and female bore(s) 73, 69, for example as shown in
A pin spread space 80 may be applied during molding proximate a connector end 79 of the female pin(s) 81 to leave an area for the female pin(s) 81, open to the connector end, to expand into without interference from the surrounding female insulator 83 during interconnection with a male AISG connector wherein a male pin of the mating connector is inserted within the open end of each female pin 81, slightly expanding the diameter of each female pin 81 in a secure electrical interconnection.
In compliance with an AISG female connector interface, an inner diameter of the female bore 69 is provided with an interior thread 25, formed for example via a threaded mold collar unthreaded or retracted radially inward from the threads formed thereby during mold separation. Further to the AISG connector specification, to avoid the possibility of rotational slipping, and therefore damage to the female pin(s) 81, the female insulator 83 is provided with a key slot 89 extending inward from an outer diameter of the female insulator 83. Similarly, the male connector portion 71 is provided with an exterior thread 25 around an outer diameter of the male connector portion 71, which protrudes from the flange portion 63 towards the connector end 79. To avoid the possibility of rotational slipping, and therefore damage to the male pin(s) 87, the male insulator 85 is further provided with a key 91 protruding inward from an inner diameter of the male bore 73.
Alternatively, the male 85 and female insulators 83 may be formed in the first step around the respective male and female pins 78 and 81 and the inner body 17 injection molded around them in the second molding step.
In further embodiments, for example where electrical isolation is desired between the inner body 17 of each of a plurality of connectors, one skilled in the art will appreciate that a shared outer body of polymeric material may be applied as the flange and base portion(s) 63,65 supporting each of the individual connectors aligned and environmentally sealed as desired.
Although the present embodiment is demonstrated with two connectors sharing a common inner body 17, as shown in
By minimizing the use of metal, and further the possible substitution of reduced cost metal alloys where applicable, the invention may provide a significant materials cost and weight savings. By replacing metal machining with injection molding technology, the number of separate sub-elements is significantly reduced, manufacturing is simplified, numerous assembly steps are eliminated and the required skill level(s) of manufacturing personnel are each significantly reduced. Because numerous prior elements are multi-shot injection molded directly upon one another, the number of pathways between discrete components is reduced, resulting in a connector with fewer environmental seal(s) 31 that may provide improved long term sealing characteristics.
Where in the foregoing description reference has been made to ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.
This application is a continuation-in-part of commonly owned co-pending U.S. Utility patent application Ser. No. 12/559,176, titled “Multi-shot Coaxial Connector and Method of Manufacture”, filed Sep. 14, 2009 by Kendrick Van Swearingen and Nahid Islam, currently pending, which is a continuation-in-part of commonly owned U.S. Utility patent application Ser. No. 12/191,922, titled “Multi-shot Coaxial Connector and Method of Manufacture”, filed Aug. 14, 2008 by Kendrick Van Swearingen, patented as U.S. Pat. No. 7,607,942 on Oct. 27, 2009.
Number | Date | Country | |
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Parent | 12191922 | Aug 2008 | US |
Child | 12882242 | US | |
Parent | 12559176 | Sep 2009 | US |
Child | 12191922 | US |