An indexable cutting insert for a cutting tool for material processing machines has a first axis of symmetry, at least one fastening bore passing through the indexable cutting insert parallel or coaxially to this first axis, two groups of main cutting edges, secondary cutting edges and cutting corners having a second axis of symmetry rotationally symmetrically opposite one another. At least the main cutting edges enclose an acute cutting edge angle with a plane oriented orthogonally to the first axis of symmetry. A cutting insert holder holds and fixes an indexable cutting insert. A recess for receiving the indexable cutting insert is on an elongated base body with polygonal cross-section. A support surface for supporting the indexable cutting insert is rotated about the base-body longitudinal axis and tilted about a second axis, a line of intersection between the rotated support surface and a plane perpendicular to the longitudinal axis.

The invention relates to a cutting tool comprising a main part which extends along a longitudinal center axis or rotational axis, at least one cutting insert holder mounted on the main part such that it can be radially adjusted, and an adjusting device for adjusting the position of the cutting insert holder relative to the main part. The adjusting device comprises a threaded sleeve which is non-rotatably but axially movably mounted in the main part and a screw drive driving the threaded sleeve.

In an indexable rotary cutting tool of the present invention, a cutting edge portion of an insert includes a peripheral cutting edge, a bottom cutting edge, a cutting edge of a corner R, and a chamfered surface, a radial rake angle () of the cutting edge of the corner R has a negative value in an entire edge length region of the cutting edge of the corner R, and the radial rake angle () becomes a minimum value at an intermediate portion located between a pair of boundary points (P, Q) in the cutting edge of the corner R.

A parting-off insert for relatively high feed includes a rake surface including a reinforced front sub-edge extending between two convex corner sub-edges. A cutting width W.sub.C is defined between distal points of the first and second convex corner sub-edges. The cutting width W.sub.C fulfills the condition: W.sub.C6 mm. The front sub-edge including a minimum front sub-edge thickness T.sub.F fulfilling the condition: T.sub.F>0.20 mm.

An insert includes a first surface having a corner portion, a second surface, a third surface, and a cutting edge. The cutting edge is provided with a first cutting edge located on the corner portion and a second cutting edge adjacent to the first cutting edge, and the third surface is provided with a first portion located along the first cutting edge and a second portion located along the second cutting edge. the second portion includes a first region having a first end portion and a second end portion, and a second region having a third end portion and a fourth end portion. An inclination angle 212 at the second end portion is greater than an inclination angle 211 at the first end portion, and an inclination angle 222 at the fourth end portion is smaller than an inclination angle 221 at the third end portion.

A cutting insert may include a base member including a plurality of tungsten carbide particles. In cases where a particle diameter distribution of the tungsten carbide particles is measured at intervals of 0.025 m, the particle diameter distribution may include, as a maximum peak and a second peak, a first peak value that appears in a particle diameter range of 0.5-0.9 m, and a second peak value that appears in a particle diameter range of 1.1-1.5 m. A value of a particle diameter distribution frequency is larger than zero at a valley part where a value of the particle diameter distribution frequency reaches a minimum between the first peak value and the second peak value.

An insert holder has a holder longitudinal axis defining opposite forward to rearward directions, a holder end surface located at a forward end thereof, and a holder peripheral surface extending circumferentially about the holder longitudinal axis. The insert holder has upper and lower jaws which are spaced apart by a clamping recess recessed in the holder end surface. The upper jaw is resiliently movable with respect to the lower jaw upon rotation around an angled pivot axis. The insert holder includes a forwardly located insert mounting portion which includes a forwardly protruding clamping finger and a forwardly protruding support rib. The clamping recess is defined partially by an elongated recess hinge surface formed on an angled hinge portion. The recess hinge surface includes a first hinge end and a second hinge end, longitudinally spaced apart from one another. The second hinge end is located forward of the first hinge end.

An insert holder has a holder longitudinal axis defining opposite forward to rearward directions, a holder end surface located at a forward end thereof, and a holder peripheral surface extending circumferentially about the holder longitudinal axis. The insert holder has upper and lower jaws which are spaced apart by a clamping recess recessed in the holder end surface. The upper jaw is resiliently movable with respect to the lower jaw upon rotation around an angled pivot axis. The insert holder includes a forwardly located insert mounting portion which includes a forwardly protruding clamping finger and a forwardly protruding support rib. The clamping recess is defined partially by an elongated recess hinge surface formed on an angled hinge portion. The recess hinge surface includes a first hinge end and a second hinge end, longitudinally spaced apart from one another. The second hinge end is located forward of the first hinge end.

A cutting insert may include a first surface and a second surface. The first surface may include a first side, a first corner, a second corner, and a breaker part. The breaker part may include a first segment, a second segment, and a third segment. The first segment may be an inclined surface inclined so as to approach the second surface as going away from the first side. The third segment may be an inclined surface inclined so as to separate from the second surface as going away from the second segment. In a front view of the first surface, a maximum value at a side of the second corner may be greater than a maximum value at a side of the first corner in a distance from the first side to a top portion of the third segment on an orthogonal line with respect to the first side.

The present invention relates to a tool bit replaceable rotary cutting tool and a rotary cutting method and a tool bit mounting method thereof and belongs to the field of hole machining in the machining industry. At present, a twist drill for drilling is of an integrated structure, and when service life of a tool bit is exhausted, the whole drill is required to be replaced, so that cost is relatively high. For a tool bit replaceable drilling tool, in a drilling process, radial and axial acting forces on a tool bit are relatively strong and thus may cause the conditions of imprecise drilling caused by radial displacement of the tool bit at a joint and the like, a replaceable structure of the tool bit makes the joint of the tool bit of the drilling tool relatively weak and a design of a chip groove makes a substrate of the drilling tool weaker. According to the tool bit replaceable rotary cutting tool of the present invention, a tool bit is detachably connected with a tool bar, and V-shaped positioning surfaces are adopted for a joint of the tool bit and the tool bar, so that a good tool bit positioning and fixation effect is achieved, and the tool bit is unlikely to deviate; a design with different helical angles is adopted for a chip groove, so that strength of the tool bar is strengthened; due to design of cooling guide grooves, a cooling effect is improved; and the tool bit is easy to mount and dismount.