Hollow metal screw and method of making

A method for making a hollow screw, comprising the steps of:

• forming an elongated and hollow body having a wall thickness of about 0.2 to about 0.7 millimeters from a generally flat metal material;
• clipping and flattening one end of the elongated and hollow body into a desired size and shape of a screw head;
• annealing for about 1 hour at an elevated temperature of about 950-980 degrees Celsius to soften the elongated and hollow body and the screw head;
• rolling a plurality of threads to at least a portion of the exterior of the softened elongated and hollow body;
• and
• hardening the hollow screw to a hardness comprising 42 Rockwell C, wherein the threads comprise a strength of about 1200-1400 MPa.

A method for making a hollow screw, comprising the steps of:

• forming a shallow cup and a radially outwardly extending rough cut flange from a generally circular flat metal material;
• extruding an elongated and hollow body from the shallow cup;
• clipping and flattening the generally radially outwardly extending rough cut flange to the desired size and shape of a screw head;
• inverting the screw head into a central curved dome with an outwardly extending skirt;
• reconing the central curved dome into a polygonal shape;
• stamping the skirt into an integral washer;
• annealing to soften at least the elongated and hollow body;
• inserting a stability pin into the elongated and hollow body, the stability pin comprising an outer diameter approximately the size of an inside diameter of the elongated and hollow body, the stability pin supporting the peripheral wall therein;
• rolling a plurality of threads to at least a portion of the exterior of the softened elongated and hollow body;
• stamping a spline recess to the screw head;
• and
• hardening the hollow screw.

A method for making a hollow screw, comprising the steps of:

• forming a shallow cup having a radially outwardly extending rough cut flange at one end thereof from a generally flat metal material;
• extruding an elongated and hollow body from the shallow cup;
• clipping and flattening the generally radially outwardly extending rough cut flange to the desired size and shape of a screw head;
• annealing to soften at least the elongated and hollow body;
• rolling a plurality of threads to at least a portion of the exterior of the softened elongated and hollow body, thereby forming the elongated and hollow body into a substantially smooth shank portion and a threaded portion;
• inverting the screw head into a generally central curved dome with an outwardly extending skirt;
• reconing the central curved dome into an outer polygonal shape;
• stamping the skirt into an integral washer;
• and
• hardening the hollow screw.

A method for making a hollow screw, comprising the steps of:

• forming an elongated and hollow body having a wall thickness of about 0.2 to about 0.7 millimeters from a generally flat metal material;
• clipping and flattening one end of the elongated and hollow body into a desired size and shape of a screw head;
• inverting the screw head into a generally central curved dome with an outwardly extending skirt;
• reconing the central curved dome into an outer polygonal shape;
• stamping the skirt into an integral washer;
• annealing for about 1 hour at an elevated temperature of about 950-980 degrees Celsius to soften the elongated and hollow body and the screw head;
• rolling a plurality of threads to at least a portion of the exterior of the softened elongated and hollow body;
• and
• hardening the hollow screw to a hardness comprising 42 Rockwell C, wherein the threads comprise a strength of about 1200-1400 MPa.