A rotary tool of the present aspect has a body and a cutting edge positioned on the outer periphery of the body. The cutting edge has a first section and a second section when viewed on an imaginary plane defined by cutting a rotational trajectory of the rotary tool on a plane including a rotational axis. The first section has a first region and a second region. A first radius of curvature of the first region is greater than a second radius of curvature of the second region in at least one of a plurality of the first sections.

A roughening tool for roughening the cylindrical surface of a bore in a particular metallic workpiece, e.g. the piston running surface of a cylinder bore or cylinder liner in an internal combustion engine, by generating a defined microstructure of a plurality of circumferentially spaced apart circumferential microgrooves. The roughening tool has a tool main body which can be driven in rotation about an axis of rotation and a multiplicity of circumferentially cutting cutting tools arranged at a defined axial distance from one another on the tool main body. According to the invention, the cutting tools are each formed from a disc milling cutter and each disc milling cutter has at least one cutting element with a multiplicity of cutting teeth arranged at an axial distance from one another. In addition, a method for roughening a cylindrical surface.

A formed rotary cutting tool includes a cutting edge defining a cutting edge diameter that is increased and reduced in a direction of an axis of the tool, so as to have at least one neck portion in which the cutting edge diameter is minimized. The cutting tool includes a roughing portion which is provided on a periphery thereof and which is constituted by a succession of protrusions and recesses arranged in the direction of the axis. The roughing portion includes (i) a fine roughing portion that is provided in at least one of the at least one neck portion, and (ii) another portion that is provided in a portion that is other than the at least one of the at least one neck portion. The fine roughing portion of the roughing portion is different in characteristics from the above-described another portion of the roughing portion.

A multi-flute ball end mill of the present invention includes: a shank portion configured to rotate about a rotational axis; a cutting edge portion; three or more ball edges formed on the cutting edge portion; gashes formed between the ball edges; peripheral cutting edges continuous with end portions of the ball edges on the shank portion side; and flutes formed between the peripheral cutting edges continuously with the gashes. The degree of curvature of the ball edges is 35% to 55%. Each of the gashes includes four faces of a rake face of each of the ball edges, a gash wall face, a first gash face, and a second gash face. The second gash face is formed such that the closer the second gash face is to the rotation center point, the more inwardly the second gash face enters a second face of each of the ball edges.

A rotary cutting tool has a plurality of circumferentially spaced grooves, each having a plurality of cutting inserts mounted. Each cutting insert has a wave-shaped major cutting edge, a corner cutting edge, and a minor cutting edge. The cutting inserts are arranged such that, the phases of the waves of the rotational trajectories formed by the cutting inserts that are adjacent to each other in a direction along the tool rotational axis coincide with each other in one groove. Also, the rotational trajectories of at least part of cutting edge portions of at least some cutting inserts are overlapped with each other in the direction of the tool rotational axis. Accordingly, even when the cutting edge portion is used as a major cutting edge and as an inner cutting edge, it is still possible to reduce cutting load and suppress breakage.

The invention relates to an apparatus for processing cylinder walls of internal combustion engines (1), including a cutting element (4). The cutting element (4) is arranged on a rotary cutting ring (3). The cutting element (4) has a slit contour (5) with a plurality of cutting edges (6) arranged next to each other in a direction of an axis of rotation of the rotary cutting ring. And, the individual cutting edges (6) face in a direction of rotation of the rotary cutting ring.

In a roughing end mill, an end mill main body is provided with: a peripheral cutting edge; an end cutting edge; and a corner cutting edge formed between the peripheral cutting edge and the end cutting edge. A roughing part having a waveform pattern of recesses and protrusions is formed in the peripheral cutting edge, and a phase of the recesses and protrusions of the roughing part of one chip discharge flute is shifted with respect to that of the other chip discharge flute adjacent to the one chip discharge flute. A foremost protrusion of the roughing part of one peripheral cutting edge is located closer to a distal end of the end mill main body than those of the other peripheral cutting edges, a peak of the foremost protrusion of the one peripheral cutting edge is aligned with another peak of the corner cutting edge adjacent to the one peripheral cutting edge. Also, a peak of a foremost protrusion of the roughing part of each of the other peripheral cutting edges is connected to another peak of the corner cutting edge adjacent to the other peripheral cutting edge by another straight portion extending in a linear manner.

A roughing end mill includes: an end mill main body rotated about an axis; and four or more of outer peripheral cutting edges provided on an outer circumference of a tip part of the end mill main body spaced apart in a circumferential direction, each of the outer peripheral cutting edges extending from a tip of the end mill main body to a rear side, wherein each of outer peripheral cutting edges includes a waveform cutting edge that is concaved and convexed in a radial direction, a phase is shifted within one pitch, and the waveform cutting edges of the outer peripheral cutting edges have one or more parts, in which phases of the waveform cutting edges are sequentially shifted multiple times toward a rear end side of the end mill main body, and shifted the same multiple times toward a tip end side of the end mill main body.

The present invention provides a tool body (20) for use in an indexable rotary cutting tool, the tool body (20) having a rotational axis and a substantially cylindrical shape. Spiral grooves (28) are formed so as to extend from a base end side of the tool body to a leading end side in a peripheral surface (23) of the tool body. The spiral grooves (28) each have a plurality of insert seats (30) formed so as to be shifted from each other from the base end side toward the leading end side. The insert seats (30) each have a bottom surface (31) and first and second side surfaces (32, 33) that extend so as to intersect with the bottom surface (31). The first side surface (32) faces the base end side of the tool body (20), and the second side surface (33) faces the leading end side of the tool body (20) and is located on the base end side with respect to the first side surface (32). In at least one insert seat (30) located closer to the base end side with respect to an insert seat (30) located closest to the leading end side of the tool body (20), a length (L1) of the first side surface (32) is longer than a length (L2) of the second side surface (33).

Even if chips enter a gap between a flank face and a surface to be worked, the defect of the flank face or a cutting edge is suppressed by the control of the flow of the chips. A plurality of cutting edges, which are undulated in wave forms in a direction of an axis, are formed on an outer periphery of a front end portion of an end mill body rotating about the axis so that phases of the wave forms are displaced from each other in a path of rotation about the axis; flank faces of the cutting edges are covered with a coating film; and rough surface regions and smooth surface regions are alternately formed on the surface of at least portions of the coating film, which are close to the cutting edges, in the direction of the axis.