Encapsulated fastener and method and tooling for manufacturing same

• US 7,896,751 B2
• Filed: 03/30/2010
• Issued: 03/01/2011
• Est. Priority Date: 07/21/2005
• Status: Active Grant

• Current Assignee: Steven L. Thompson
• Original Assignee: Steven L. Thompson
• Inventors: Thompson, Steven L.
• Primary Examiner(s): Tolan; Edward
• Application Number:
  US12/750,493
• Publication Number:
  US 20100184522A1
• Time in Patent Office: 336 Days
• Field of Search: 470/2, 470/5, 470/18, 470/24, 470/48, 470/49, 470/51, 470/87, 470/187, 264/263, 264/271.1, 264/274, 264/275, 264/278, 425/125, 425/127, 425/517
• US Class Current: 470/18
• CPC Class Codes: F16B 37/14 Cap nuts; Nut caps or bolt caps

Abstract

An encapsulated fastener includes a nut having a face with a concave gap adapted to receive a bolt. The nut is encapsulated by an encapsulation including an extension, which includes a tube adapted for receiving a portion of the bolt and a flange adapted for engaging a face of the nut. The encapsulation extension is placed on the nut in an overmolding tool, wherein an encapsulation base is injection molded over a portion of the encapsulation extension. The encapsulation base encapsulates the nut and extends into the nut concave gap forming a base foot and washer protrusion. The nut is encapsulated except for its bore which is sealed off during the overmolding process by a spring-mounted mandrel. Alternative embodiments of the invention include tubes with different configurations for contacting the bolt whereby the tube or cylinder is reinforced. A method and tooling for manufacturing the encapsulated fastener are also provided.

Claims

1. An encapsulated fastener manufacturing method, which comprises the steps of:

providing an encapsulation extension molding tool adapted for molding encapsulation extensions;

molding with said extension molding tool an encapsulation extension including a tube with proximate and distal ends and a tube bore open at said proximate end and closed at said distal end;

molding said encapsulation extension with a flange located at said tube proximate end and including a flange face;

providing a nut with first and second faces, an internally-threaded bore extending between and open at said faces and at least one sidewall, said nut first face having a concave shoulder forming a gap at said sidewall;

placing said nut on said encapsulation extension with said flange face engaging said nut second face;

providing an overmolding tool with first and second mold halves with respective first and second mold cavities and a mandrel with an end adapted to engage said nut and close said nut bore;

closing said mold halves;

partially inserting said mandrel end into said nut bore and thereby pressing said nut and encapsulation extension into said first mold cavity;

injecting molten plastic into said first and second cavities to overmold said nut, said flange and said tube proximate end with an encapsulation base having a side and a base foot extending into said nut first face concave shoulder, said base foot partially enclosing said nut first face;

fusing said encapsulation base onto said flange and said tube proximate end; and

forming with said mandrel an encapsulation base opening adapted for receiving a bolt in said encapsulation base in alignment with said nut bore.

2. The method according to claim 1, which includes the additional steps of:

encircling said nut first face with said concave shoulder;

encircling said nut concave shoulder with said encapsulation base foot;

forming a washer protrusion with said base foot and extending said washer protrusion from said nut first face; and

pressing said washer protrusion against a surface of an element being fastened.

3. The method according to claim 1, which includes the additional step of forming a longitudinally-extending external rib on said encapsulation base side.

4. The method according to claim 1, which includes the additional steps of:

forming multiple, longitudinally-extending, elongated internal ribs in said extension tube bore;

extending said internal ribs between said tube proximate and distal ends; and

positioning and spacing said internal ribs in said tube bore in order to form an interference fit between said bolt and said internal ribs with said bolt inserted into said tube bore.

5. The method according to claim 1, which includes the additional step of providing a compression spring in said second mold half and engaging said mandrel with said compression spring.

6. An encapsulated fastener manufacturing method, which comprises the steps of:

providing an encapsulation extension molding tool adapted for molding encapsulation extensions;

molding an encapsulation extension including a tube with proximate and distal ends and a tube bore open at said proximate end;

molding said encapsulation extension with a flange including a flange face and located at said tube proximate end;

providing a nut with first and second faces, an internally-threaded bore extending between and open at said faces and at least one sidewall, said nut first face having a concave shoulder forming a gap at said sidewall;

encircling said nut first face with said concave shoulder;

placing said nut on said encapsulation extension with said flange face engaging said nut second face;

providing an overmolding tool with first and second mold halves with respective first and second mold cavities and a mandrel with an end adapted to engage said nut and close said nut bore;

providing a compression spring in said second mold half and engaging said mandrel with said compression spring;

closing said mold halves;

partially inserting said mandrel end into said nut bore and thereby pressing said nut and encapsulation extension into said first cavity;

injecting molten plastic into said first and second cavities to overmold said nut, said flange and said tube proximate end with an encapsulation base having a side, said encapsulation base having a longitudinally-extending rib on said encapsulation base side, a base foot extending into and engaging said nut first face concave shoulder;

encircling said nut concave shoulder with said encapsulation base foot;

forming a washer protrusion with said base foot and extending said washer protrusion from said nut first face;

pressing said washer protrusion against a surface of an element being fastened;

fusing said encapsulation base onto said flange and said tube proximate end; and

forming an encapsulation base opening within said washer protrusion and adapted for receiving a bolt in said encapsulation base in alignment with said nut bore.

7. Tooling for manufacturing an encapsulated fastener including a nut having first and second faces, multiple sidewalls and an internally-threaded nut bore extending between said faces, said nut first face having a concave shoulder forming a gap beneath said sidewall, an encapsulation extension including a flange with a concave proximate face placed on said nut second face and an encapsulation base overmolded around said nut and a portion of said encapsulation extension, which tooling comprises:

an injection mold including a mold cavity adapted for injection molding an encapsulation extension including a flange with a concave proximal face, multiple sides, an extension tube with a proximal end connected to said flange, a closed distal end and a tube bore, said tube bore including an internal rib extending between said tube bore proximate end and said distal end;

an overmolding tool including a lower half with a lower cavity for receiving the encapsulation extension with said nut second face placed on said flange concave face and said nut and tube bores aligned;

said overmolding tool including an upper half with an upper cavity, a sidewall and a mandrel receiver, said upper cavity sidewall including multiple external rib subcavities and a washer protrusion subcavity having a convex corner;

a mandrel reciprocably received in said mandrel receiver and including a conical lower end and an annular shoulder located above said lower end;

a compression spring located in said mandrel receiver and engaging said mandrel, said compression spring biasing said mandrel downwardly;

said overmolding tool having a closed position with said mandrel lower end received in said nut bore and said mandrel shoulder engaging said nut first face;

said overmolding tool having an open position with said upper half spaced from said lower half;

an ejector device mounted in said mold lower half and having a retracted position with said overmolding tool in its closed position and an extended position with said overmolding tool in its open position, said ejector device being adapted for ejecting said encapsulated nut from said mold lower half; and

a subgate in said overmolding tool communicating with said upper and lower cavities with said overmolding tool in its closed position, said subgate being adapted for injecting material into said cavities.