A deburring tool (7) for deburring of edges of transverse recesses (3, 3a-i), which diverge from a main borehole (2), consisting of a shaft (8, 9) driven to turn about the tool axis (11), which is deployable and retractable in the forward feed direction into the main borehole, and on the lower end of which at least one knife window (26) is arranged, in which at least one spring-loaded knife (10, 10′, 10″, 10′″, 10″″) is arranged roughly perpendicular to the tool axis (11), so as to be shiftable, which on its front end has at least one cutting edge (10a, 10b) which encounters the edge of the transverse recess (3, 3a-i), and deburrs same, wherein the knife (10, 10′, 10″, 10′″, 10″″) consists of two cutting edges (10a, 10b) opposite in the rotational direction (12, 13), which act to cut equally for the right and left passes (12, 13), with one cutting edge (10a) being configured to cut for the rightward pass (12), both in forward motion (38a) and in rearward motion, and the other cutting edge (10b), being configured to cut for the leftward pass (13), both in forward motion (38a) and in rearward motion, and that the two cutters (10a, 10b) with their cutting edges are placed at a slant and with arch shape at an angle between 0° and 90°, but preferably between 5° and 45° to the tool axis (11) and thus to the longitudinal axis (2a) of the main borehole (2).

This cutting insert has: as cutting edges, arcuate cutting edges that are of an arc shape protruding toward an outer circumference side of a distal end. A chisel part is formed at an intersecting ridge line part between the flank faces of the pair of arcuate cutting edges. A round honing is formed on the cutting edge tip of the arcuate cutting edge at least in a range where a radial angle is 30 or less. A curvature radius of the round honing in a cross section perpendicular to the edge length direction of the arcuate cutting edge is 20 to 40 m. A chisel angle formed between the distal end part of the arcuate cutting edge and a chisel edge of the chisel part is 150 to 170 as seen in an insert front view.

In an end mill, eight peripheral cutting edges having a helical shape and g a larger outer diameter than that of a shaft portion are in a cutting portion in a circumferential direction. For one peripheral cutting edge of the eight peripheral cutting edges, when a cut length of the peripheral cutting edge along an axial direction is L, a twist angle of the peripheral cutting edge is , and a circumferential distance at a lower end of the peripheral cutting edge between the peripheral cutting edge and another peripheral cutting edge adjacent to a tool rotation direction rear side of the peripheral cutting edge is a, n expressed by the following equation is approximately 1 for all of the eight peripheral cutting edges in at least a half region of the cut length from the lower end of the peripheral cutting edge.

n=(Ltan )/(2a)

A rotary cutting tool includes a shaft having and outer surface and having a longitudinal axis, a plurality of helical flutes formed in the shaft about the longitudinal axis, a plurality of helical cutting edges formed at an interface with the outer surface and a respective helical flute about the longitudinal axis, and a plurality of end cutting edges located on an axial distal end of a cutting portion of the shaft, the end cutting edges being contiguous with a corresponding one of the plurality of helical cutting edges and forming a corner in the transition between each of the end cutting edges and the corresponding one of the plurality of helical cutting edges. A hone edge extends along a portion of each of the end cutting edges, the associated corner and a portion of the corresponding one of the plurality of helical cutting edges.

An end mill having an eccentric flat relief formed thereon is proposed. The eccentric flat relief (simply referred to as ELF) includes at least three flat relief surfaces continuously arranged along a trajectory of an eccentric relief. Accordingly, the end mill, which combines strengths of the flat relief and an eccentric relief, has excellent rigidity and a heat discharge characteristic.

A method for milling a workpiece by way of at least one substantially polygonal cutting insert, which is arranged in a tool holder. A spindle axis of the tool holder encloses an angle of more than 0 with a plane normal to a machined workpiece surface. An effective lead angle between a main cutting edge of the cutting insert and the machined workpiece surface lies between 0 and 20.

A method for forming dimples on a workpiece includes providing a rotary cutting tool. The rotary cutting tool includes a cutting edge that protrudes in a leading direction parallel to a longitudinal axis of the tool. The cutting edge extends from a position at the leading end of the rod-shaped main body that is radially offset from the longitudinal axis. The rotary cutting tool is set such that the longitudinal axis of the rotary cutting tool is inclined relative to a line perpendicular to the processing surface of the workpiece. The rotary cutting tool is moved along the processing surface while the rotary cutting tool is rotated about the axis. The processing surface is cut by the cutting edge to form the dimples, which are spaced apart from each other on the processing surface.

A cutting insert has: an upper surface; a lower surface; a side surface, having a first surface and a second surface disposed opposite each other between the upper surface and the lower surface; and a first cutting edge. The lower surface has a plurality of slots extending from a side of the first surface to a side of the second surface. In addition, when viewed from a side of the lower surface, if the angle between a ridge line on which the upper surface and the first surface intersect and an imaginary extension line of the plurality of slots is defined as 1, and the angle between a ridge line on which the lower surface and the first surface intersect and the imaginary extension line is defined as 2, then 2>1.

Provided is a cutting insert capable of suppressing edge fracture when a work having high hardness is machined. A cutting insert includes two end surfaces having a plurality of corner parts and opposed to each other, a peripheral side surface extending between the two end surfaces, and a cutting edge formed at an intersecting edge between at least one of the two end surfaces and the peripheral side surface. The cutting edge has at least a first corner edge, a second corner edge, a major cutting edge, and an end cutting edge. The end cutting edge has a circular-arc shape, which projects outward, as viewed from the side of the end surface. The end cutting edge has a width which is from 15% to 50% of the width of the cutting insert. The end cutting edge has an arc radius which is from to 1/1 of the width of the cutting insert.

This cutting insert has: as cutting edges, arcuate cutting edges that are of an arc shape protruding toward an outer circumference side of a distal end. A chisel part is formed at an intersecting ridge line part between the flank faces of the pair of arcuate cutting edges. A round honing is formed on the cutting edge tip of the arcuate cutting edge at least in a range where a radial angle is 30 or less. A curvature radius of the round honing in a cross section perpendicular to the edge length direction of the arcuate cutting edge is 20 to 40 m. A chisel angle formed between the distal end part of the arcuate cutting edge and a chisel edge of the chisel part is 150 to 170 as seen in an insert front view.