Mandrel bladder end fitting

An end fitting configured for securing a fluid-tight sealing connection with an open end of a mandrel bladder, the end fitting, comprising:

• an outer body having a longitudinal axis, and an interior wall extending about the longitudinal axis, the interior wall defining a first clamping surface, wherein the outer body has first and second axially oriented interior volumes separated by a radially extending annular step, the volumes being defined by first and second circumferentially extending interior walls, respectively, with the first volume having a larger interior wall than the second, and wherein the first interior wall defines the first clamping surface;
• an expansion assembly configured for containment within the first clamping surface, the expansion assembly comprising a central core coaxially aligned with the outer body, an array of expansion wedges situated circumferentially about the central core and between the central core and the first clamping surface, the expansion wedges defining radially outer surfaces that collectively define a second clamping surface, and an axially extending threaded member having a socket head at one end with an externally threaded shank extending from the socket head, the central core includes an interior threaded aperture, and wherein the threaded shank cooperates with the interior threaded aperture;
• and
• a washer,
• wherein, relative to the longitudinal axis of the outer body, the second clamping surface is restricted to orthogonal movement with respect to the first clamping surface, such that the end fitting is adapted to prevent axial motion between the first and second clamping surfaces while securing a fluid-tight connection with an open end of a mandrel bladder, and wherein the annular step is defined by an annular wall within the first volume, and the washer is seated against the annular step, and wherein the expansion wedges are axially juxtaposed against the seated washer, and at least one beveled washer spring is interposed between the socket head and a second side of the washer within the second volume, the washer circumferentially overlying a portion of the threaded member and producing an axial reaction between the socket head and the washer.

A mandrel bladder end fitting assembly, comprising:

• a mandrel bladder having an openable end along an axis;
• an end fitting having an outer body situated about the openable end along the axis, the outer body having juxtaposed first and second interior volumes concentrically situated about the axis, the volumes having first and second diameters, respectively, with an interface of the volumes being defined by a radially oriented annular step;
• an expansion plug assembly configured for containment within the first interior volume of said outer body, the expansion plug assembly comprising a central core having an internally threaded aperture, with a plurality of flat, angled sides, each side defining a cam;
• the expansion plug assembly further comprising a separate plurality of mated expansion wedges, each expansion wedge corresponding with one cam;
• an elongated cap screw defined by an elongated hollow body having a socket head at one end with an externally threaded portion extending from the socket head, wherein an unthreaded portion is situated between the socket head and threaded portion;
• a flat washer seated against the annular step;
• at least one beveled washer spring circumferentially overlying the unthreaded portion of the cap screw, reacting between the socket head and the flat washer;
• wherein when the socket head is rotated in one direction, the cap screw pulls the central core axially toward the flat washer, forcing the expansion wedges radially outwardly toward the outer body;
• wherein the radially outward movement of the expansion wedges is configured to clamp the open end of the mandrel bladder against the outer body, and to achieve a fluid tight seal when the bladder contents are under positive fluid pressure;
• and
• wherein an adhesive silicone material overlies the openable end of the mandrel bladder when the openable end is clamped between the expansion wedges and the outer body.

A method of making a mandrel bladder end fitting assembly, comprising the steps of:

• forming a mandrel bladder having an openable end along an axis;
• applying an end fitting about the openable end along the axis of the outer body, with the outer body having juxtaposed first and second interior volumes concentrically situated about the axis, the volumes having first and second diameters, respectively, with an interface of the volumes being defined by a radially oriented annular step;
• applying an expansion plug assembly configured for containment within the first interior volume of said outer body, the expansion plug assembly comprising a central core having an internally threaded aperture, with a plurality of flat, angled sides, each side defining a cam;
• the expansion plug assembly further comprising a separate plurality of mated expansion wedges, each expansion wedge corresponding with one cam;
• applying an elongated cap screw, defined by an elongated hollow body having a socket head at one end with an externally threaded portion extending from the socket head, to the internally threaded aperture, and wherein the cap screw has an unthreaded portion situated between the socket head and threaded portion;
• applying a flat washer seated against the annular step;
• configuring at least one beveled washer spring to circumferentially overlie the unthreaded portion of the cap screw for reacting between the socket head and the flat washer;
• wherein when the socket head is rotated in one direction, the cap screw pulls the central core axially toward the flat washer, forcing the expansion wedges radially outwardly toward the outer body;
• wherein the radially outward movement of the expansion wedges is configured to clamp the open end of the mandrel bladder against the outer body, and to achieve a fluid tight seal when the bladder contents are under positive fluid pressure;
• and
• applying an uncured adhesive silicone material in a layer to the openable end of the mandrel bladder, and curing the silicone material before the openable end is clamped between the expansion wedges and the outer body.