Weldable plastic fastener

An assembly for maintaining a clamping fastening force on panels, the assembly comprising:

• an upper and a lower panel each having top and bottom surfaces and a bore extending through each of the panels from the top to the bottom surface;
• a plastic bolt having a head and a shank having a first predetermined diameter with the shank extending from the bolt head;
• a plastic nut having a first end and a second end with a central bore wall extending through the nut from the first end to the second end to define a shank receiving bore having a second predetermined diameter;
• a plurality of axial plastic projection members on the bore wall with the projection members defining a third predetermined diameter less than the shank first diameter to provide an interference fit with the shank when the nut is mounted on the shank with the nut and shank being bonded upon reducing the regions between the projections and shank to a flowable state which then solidifies to thereby bond the nut on the shank;
• the bolt shank being inserted in aligned bores of the panels and the nut is mounted on the end of the bolt shank distal from the bolt head until it engages the lower panel bottom surface to exert a clamping force on the panels by the bolt head on the upper panel top surface and the nut on the lower panel bottom surface;
• and
• a bonded plastic interface between the shank and projections having been defined by their respective plastics having been liquified to a flowable state to intermix and then solidified to maintain the clamping force exerted by the bolt head and nut on the panels.

A plastic nut for welding to a plastic bolt having a shank with a predetermined diameter, said plastic nut comprising:

• a body of plastic;
• exterior flats on the body defining a peripheral surface for the body and to be engaged by a tool to turn the nut;
• an interior surface in the plastic body defining a bore with an axis in the body to receive therein the bolt shank;
• a plurality of axially-extending projections in the bore projecting radially inwardly toward the axis;
• and
• the interior axially-extending surfaces on the projections being spaced from one another about the interior surface of the bore and defining a diameter smaller than the bolt shank to have an interference fit with the bolt shank and for being liquified and for intermixing with plastic of the bolt and thereby forming a plastic bond with the bolt shank, the axially-extending projections being substantially trapezoidal in cross-section with said interior, axially-extending surfaces being smaller in size than base portions of the projections integrally joined to the interior bore surface.

A method of securing two members together with a plastic bolt having a shank and a head with a plastic nut, said method comprising the steps of:

• abutting the two members together having bolt receiving openings in the respective members being aligned to receive a bolt;
• inserting the bolt shank through the openings and abutting the bolt head against one of the members;
• providing a nut with a bore having inwardly-extending projections in the bore defining a diameter less than a diameter of the bolt shank;
• forcibly sliding the axial projections on the nut relative to the bolt shank to provide a force fit at an interface between the projections and the bolt shank when the nut is slid onto the bolt shank;
• liquefying the plastic of the bolt and nut at the interface to intermix the bolt and nut plastics;
• and
• solidifying the intermixed plastic at the interface to bond the nut to the bolt shank and thereby securing the two members together.