Abstract: A three-way indexable throwaway tip for deep-hole drilling can be used as a center cutting blade body for a drill head in either whole cutting type or uncut core break-off type applications. The throwaway tip for deep-hole drilling is of a thick plate body having a three-fold symmetry with three cutting sections that are rotationally spaced apart at a central angle of 120 degrees. When mounted on a drill head, one cutting section of the throwaway tip faces a drilling direction. The forward facing blade edge of that cutting section includes an inner blade edge shorter in blade length and an outer blade edge longer in blade length forming an apex. The outer blade edge is composed of two consecutive blade edge portions of a peak-side outer blade edge portion having a smaller outer blade edge angle and a corner-side outer blade edge portion having a larger outer blade edge angle.

Abstract: The present invention provides a method for reliable, easy, and low cost manufacturing of a drill head of such a kind that a cutting blade tip is brazed to a cutting blade mounting seat of a head body, with high dimensional accuracy and blade edge accuracy. In the manufacturing of a drill head 10 used with a screw shank 2 coupled in threading relation with a distal end portion of a tool shank 5 of a deep-hole cutting drill and with bounded circumferential face portions 22 and 23 at both sides which sandwich a male thread 21 portion adhered closely to a circumferential face of the tool shank 5, a screw shank cylindrical member 20A with a cutting stock 7 left at least on the bounded circumferential face portions 22 and 23 is welded and integrated with a rear end of a head body 1 for which cutting blade tips 30a to 30c have been brazed, thereafter cutting the cutting stock 7 of the screw shank cylindrical member 20A so as to be finished into the screw shank 2.

Abstract: A method for forming a through-hole on a work material using a drill having a drill head provided with a brazed-type cutting blade helps prevent generation of a spiral mark on an inner circumferential face of the through-hole and obtains a superior appearance and high working accuracy. In forming a through-hole H on a work material W by a drill head 1A with cutting blades 3A to 3C brazed to cutting blade mounting seats 13a to 13c, a drill head provided with roundness R on a blade edge outer end portion 31a of a cutting blade 3A responsible for cutting of the outermost periphery is used as the drill head 1A.

Abstract: A method for forming a through-hole on a work material using a drill having a drill head provided with a brazed-type cutting blade helps prevent generation of a spiral mark on an inner circumferential face of the through-hole and obtains a superior appearance and high working accuracy. In forming a through-hole H on a work material W by a drill head 1A with cutting blades 3A to 3C brazed to cutting blade mounting seats 13a to 13c, a drill head provided with roundness R on a blade edge outer end portion 31a of a cutting blade 3A responsible for cutting of the outermost periphery is used as the drill head 1A.

Abstract: A gun drill in which coolant delivered to a cutting part can be discharged intensively to a cutting chip discharge groove along with the chips, damage on the inner circumference of a drilled hole or fall of machining precision due to clogging with chips can be prevented, and cutting efficiency is enhanced by reducing rotary load and long lifetime can be attained. Coolant supply paths (10, 20) are provided in a tool shank (1) and a cutting head (2), one cutting chip discharge groove (3) is provided in the outer circumferential surface from the proximal side of the tool shank (1) to the distal end of the cutting head (2), discharge ports (22a, 22b) communicating with coolant delivery ports (21a, 21b) and a cutting chip discharge groove (3) are provided in the distal end face (2c) of the cutting head (2), and annular protrusions (4a) are formed in the outer circumferential surface of the cutting head (2) continuously over the entire circumference while bridging over the cutting chip discharge groove (3).

Abstract: A deep hole cutter for a gun drill system includes a tool shank and a cutting head with two or more cutting edges. The tool shank and the cutting head are separate members connected strongly by threads. The shavings produced by the cutting edges can be discharged together with the coolant supplied through the hole cutter. The shaving dischargeability is improved for higher cutting efficiency. The tool shank 1 has one outer axial discharge groove 3. The cutting head 2 has one outer axial discharge groove 6 in linear alignment with the discharge groove 3. The cutting head 2 also has a discharge port 7a formed in its front end. The cutting head 2 further has a bypass passage 7 formed in it and extending between the discharge port 7a and the discharge groove 6. The cutting edges 9a and 9c face the discharge groove 6. The cutting edge 9b faces the discharge port 7a.