Spade-type boring bit and an associated method and apparatus for forming metallic parts

A spade-type boring bit comprising:

• an elongate shank defining a central longitudinal axis;
• and
• a blade portion joined at a rear end to one end of said shank along the central longitudinal axis, said blade portion including:
• a pair of generally flat side segments which extend laterally in opposite directions from the central longitudinal axis, said side segments defining respective lateral planes which are parallel to each other and the central longitudinal axis, said side segments also including respective forward cutting edges wherein at least one forward cutting edge lies along a centerline which passes through the central longitudinal axis, and
• a spur joined to and extending axially from a forward end of said blade portion opposite the rear end.

A spade-type boring bit comprising:

• an elongate shank defining a central longitudinal axis:
• a blade portion joined at a rear end to one end of said shank along the central longitudinal axis, said blade portion including:
• a pair of generally flat side segments which extend laterally in opposite directions from the central longitudinal axis, said side segments including respective forward cutting edges;
• and
• a generally triangular spur joined to and extending axially from a forward end of said blade portion opposite the rear end, said spur defining a spur base along which said spur is joined to the forward end of said blade portion, a spur point aligned with the central longitudinal axis, and a pair of spur cutting edges extending along opposite sides of said spur between the spur point and the spur base such that each spur cutting edge extends radially outward of at least an innermost portion of the forward cutting edge of the adjacent side segment,
• and wherein each spur cutting edge is angularly offset from the forward cutting edge of the adjacent side segment in a predetermined direction of rotation of the spade-type boring bit when viewed along the central longitudinal axis, such that each spur cutting edge is both radially and angularly separated from the forward cutting edge of the adjacent side segment.

A spade-type boring bit having a blade portion with a predetermined cross-sectional shape, the spade-type boring bit being manufactured from a continuous metal stock according to a forging process comprising the steps of:

• incrementally advancing the continuous metal stock a predetermined linear distance such that the metal stock advances longitudinally in a downstream direction;
• clamping a leading portion of the continuous metal stock following each incremental advance of the metal stock so as to hold the leading portion in a fixed location;
• forging a portion of the continuous metal stock, upstream of the leading portion, to the predetermined cross-sectional shape of the blade portion of a respective spade-type boring bit each time the metal stock is clamped and held at the fixed location, wherein said forging step comprises forging a portion of the continuous metal stock to form the blade portion having a generally flat central segment defining a central plane, a pair of generally flat side segments joined to opposite sides of the central segment and defining respective lateral planes which are parallel to each other and which intersect the central plane at an oblique angle, and a spur joined to a forward end of the central segment;
• and
• compensating for longitudinal growth of the continuous metal stock created during each forging step by permitting upstream longitudinal movement of that portion of the continuous metal stock which is upstream of the fixed location.

A spade-type boring bit having an elongate shank defining a central longitudinal axis, a blade portion joined to one end of the elongate shank and including a pair of side segments extending laterally in opposite directions from the central longitudinal axis, and a spur joined to and extending axially from the blade portion, the spade-type boring bit being manufactured from a continuous metal stock according to a forging process comprising the steps of:

• incrementally advancing the continuous metal stock a predetermined linear distance such that the metal stock advances longitudinally in a downstream direction;
• clamping a leading portion of the continuous metal stock following each incremental advance of the metal stock so as to hold the leading portion in a fixed location;
• forging a portion of the continuous metal stock upstream of the leading portion into the blade portion of a respective spade-type boring bit each time the metal stock is clamped and held at the fixed location, wherein said forging step comprises forging a portion of the continuous metal stock to form the blade portion having the pair of generally flat side segments defining respective lateral planes which are parallel to each other and the central longitudinal axis and which include respective forward cutting edges, at least one forward cutting edge lying along a centerline which passes through the central longitudinal axis;
• and
• compensating for longitudinal growth of the continuous metal stock created during each forging step by permitting upstream longitudinal movement of that portion of the continuous metal stock which is upstream of the fixed location.

A method of drilling a hole in a workpiece comprising the steps of:

• providing a spade-type boring bit having an elongate shank defining a central longitudinal axis, a blade portion joined to one end of the elongate shank and a spur joined to and extending axially from the blade portion wherein the blade portion includes a pair of side segments extending laterally in opposite directions from the central longitudinal axis to define respective lateral planes which are parallel to each other and the central longitudinal axis, the pair of side segments also including respective forward cutting edges, at least one forward cutting edge lying along a centerline which passes through the central longitudinal axis;
• entering the workpiece with the spade-type drill bit such that the spur guides the spade-type drill bit into the workpiece;
• rotating the spade-type drill bit in a predetermined direction to form a hole in the workpiece wherein said rotating step comprises the steps of engaging and removing portions of the workpiece with the forward cutting edges of the blade portion of the spade-type drill bit, thereby creating chip swarf;
• and
• directing the chip swarf created during said rotating step in a direction perpendicular to the respective forward cutting edges;
• while preventing chip swarf from migrating radially outward in the hole and binding between the spade-type drill bit and the peripheral wall of the hole created in the workpiece.

A method of drilling a hole in a workpiece comprising the steps of:

• providing a spade-type boring bit having an elongate shank defining a central longitudinal axis, a blade portion joined to one end of the elongate shank and including a pair of side segments extending laterally in opposite directions from the central longitudinal axis and having respective forward cutting edges, and a generally triangular spur joined to and extending axially from the blade portion and including a spur base along which the spur is joined to the blade portion, a spur point, and a pair of spur cutting edges extending along opposite sides of the spur between the spur point and the spur base such that each spur cutting edge extends radially outward of at least an innermost portion of the forward cutting edge of the adjacent side segment, and wherein each spur cutting edge is angularly offset from the forward cutting edge of the adjacent side segment in a predetermined direction of rotation of the spade-type boring bit when viewed along the central longitudinal axis such that each spur cutting edge is both radially and angularly separated from the forward cutting edge of the adjacent side segment;
• entering the workpiece with the spade-type drill bit such that the spur guides the spade-type drill bit into the workpiece;
• rotating the spade-type drill bit in a predetermined direction to form a hole in the workpiece wherein said rotating step comprises the steps of engaging and removing portions of the workpiece with both the forward cutting edges of the blade portion and the spur cutting edges of the spade-type drill bit, thereby creating chip swarf;
• and
• directing the chip swarf created during said rotating step away from the surface of the workpiece engaged by the spade-type boring bit;
• while preventing chip swarf from accumulating between a spur cutting edge and the forward cutting edge of the adjacent side segment.

A method of drilling a hole in a workpiece comprising the steps of:

• providing a spade-type boring bit having an elongate shank defining a central longitudinal axis, a blade portion joined to one end of the elongate shank and a spur joined to and extending axially from the blade portion wherein the blade portion includes a generally flat central segment disposed along the central longitudinal axis and defining a central plane, and a pair of generally flat side segments joined to opposite sides of the central segment and defining respective lateral planes which are parallel to each other and which intersect said central plane at an oblique angle, each side segment also including a respective forward cutting edge;
• entering the workpiece with the spade-type drill bit such that the spur guides the spade-type drill bit into the workpiece;
• rotating the spade-type drill bit in a predetermined direction to form a hole in the workpiece such that the spade-type drill bit longitudinally advances in a forward direction wherein said rotating step comprises the steps of engaging and removing portions of the workpiece with the forward cutting edges of the blade portion of the spade-type drill bit, thereby creating chip swarf;
• and
• directing the chip swarf created during said rotating step in a longitudinally rearward direction, opposite the forward direction in which the spade-type drill bit is advanced, such that the chip swarf is removed from the surface of the workpiece engaged by the spade-type drill bit.