Medical hollow needle and method of production

A medical hollow needle comprising:

• a cylindrical member having a flow path capable of passing a fluid therein along a center axis;
• a first ground bevel face formed at a top end portion of said cylindrical member, such that said flow path is open in an oblique direction, having a first inclined angle with respect to said center axis;
• a second ground bevel face formed by rotating said cylindrical member through a first rotational angle, with respect to said center axis, having a second steeply inclined angle, and a third ground bevel face formed by rotating said cylindrical member through a second rotational angle in an opposite direction with respect to said first rotational angle having a third steeply inclined angle, both formed at said top edge portion of said cylindrical member;
• a fourth ground bevel face in a shape of a plane, formed at a position opposed to said first bevel face in an oblique direction with respect to said center axis, thereby thinning said cylindrical member;
• and
• a sharp forward edge portion formed by the intersection of at least two bevel faces.

A method for producing a needle adapted for use in medical procedures comprising the steps of:

• (a) grinding an end portion of a hollow cylindrical member so as to form a first bevel face between opposite outside walls of the cylindrical member, the first bevel face being oriented in an oblique direction relative to a central axis of the cylindrical member and having a first inclined angle with respect to said central axis;
• (b) relatively rotating and grinding said end portion about said central axis, through a first rotational angle so as to form a substantially vertical bevel face converging along a side edge of said first bevel face;
• (c) relatively rotating and grinding said end portion about said central axis, through a second rotational angle, in an opposite direction to said first rotational angle, so as to form a substantially vertical bevel face converging along another side edge of said first bevel face;
• and,
• (d) tapering the end portion of a cylindrical member along a back bevel inclined inwardly in a direction opposite from the first bevel such that a thickness of the cylindrical member is reduced leading to a point spaced radially inwardly from an extension of an outer wall of the cylindrical member.

A method of producing a hypodermic needle, said method comprising:

• grinding a top edge portion of a cylindrical member in an oblique direction relative to a center axis of said member so as to define a flow path capable of passing a fluid therein, and thereby thinning the wall thickness of said cylindrical member, so as to form a first ground bevel face in the shape of a plane;
• grinding a portion opposed to said first bevel face in an oblique direction, at a first inclined angle with respect to said center axis so as to form a second ground bevel face in which said flow path is obliquely open;
• grinding said cylindrical member by rotating through a first rotational angle with respect to said axis center, so as to form a third steeply inclined angle with respect to form a third bevel face, and by rotating said cylindrical member through a second rotational angle in an opposite direction with respect to said first rotational angle to form a fourth steeply inclined bevel grinding face;
• and
• forming a sharp forward cutting edge portion comprised of at least said second, said third and said fourth bevel faces.