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.

Provided is a cutter apparatus for machining a difficult-to-machine material, the cutter apparatus including: a cutting tool body which has a fastening portion formed at a center thereof; one or more cutters which are installed on the cutting tool body, and have superhard insert tips fixed to end portions thereof, respectively; and an angle adjusting unit which is installed in an internal space of the cutters, and adjusts angles of the cutters by spreading or retracting the cutters, so that angles of the cutters may be easily adjusted in accordance with a condition for cutting a difficult-to-machine material, in order to prevent damage to the superhard insert tips when machining a difficult-to-machine material having high hardness and high toughness.

The present invention relates to a cutting insert applicable to machining tools and the tool bearing it. The insert (1) has a cutting edge (12) which can be completely sharp or can have a rounding between R=0.030 mm and 0.050 mm, with an angle of impact (123) between 68 and 90 in both cases, and a rounded chip breaker (13), both arranged in a layer of polycrystalline diamond (PCD) (11) at least 1 mm thick covering the entire cutting surface of the insert (1).

The tool includes a body (2) formed by a core (22) coupleable to the machining center, said core externally bearing a perimetral sleeve (21) housing the cutting inserts (1), with the layer of PCD (11) thereof being in direct contact with the sleeve (21).

The invention may include a hydraulic system (23) between the sleeve (21) and the core (22).

In a method of setting heat-resistant alloy cutting conditions used to set cutting conditions under which a heat-resistant alloy is cut with a cutting tool, the cutting tool has a long shaft mounted on a spindle and extended in the axial direction and teeth formed on the shaft. The cutting conditions include a radial direction cutting amount of the cutting tool in the radial direction. When the radial direction cutting amount in which one tooth is constantly in contact with the heat-resistant alloy is given as a smallest radial direction cutting amount and the radial direction cutting amount in which three or more teeth are not in contact with the heat-resistant alloy is given as a largest radial direction cutting amount, a radial direction cutting amount of the cutting tool is set in the range from the smallest radial direction cutting amount to the largest radial direction cutting amount.

The invention relates to a rotary tool (1; 101; 201; 301; 401) for cutting large inside diameters at the outer circumference (2) of which at least one cutting edge (4; 104; 204) is arranged, comprising a support structure (10; 110; 210; 310; 410) which includes a supporting area (14; 114; 214) which indirectly or directly supports the cutting edge (4; 104; 204), and comprising a chucking portion (24; 124; 224; 324; 424) for coupling to a tool holder, wherein the support structure (10; 110; 210; 310; 410) is designed in light-weight construction and the area (14; 114; 214) of the support structure (10; 110; 210; 310; 410) indirectly or directly supporting the cutting edge (4; 104; 204) is limited regarding thermal expansion by a corset structure (12; 112; 212; 312; 412).

The use of cryogenic coolant in a machining operation in Ti, Ti-alloys or Ni-alloys together with a cutting tool of a cemented carbide substrate with a gradient surface zone with a thickness of between 50-400 m is provided. The cemented carbide substrate has a binder phase gradient with the lowest binder phase content in the outermost part of the gradient surface zone and the cemented carbide having graphite. The arrangement leads to a significantly prolonged tool life.

In a method of setting heat-resistant alloy cutting conditions used to set cutting conditions under which a heat-resistant alloy is cut with a cutting tool, the cutting tool has a long shaft mounted on a spindle and extended in the axial direction and teeth formed on the shaft. The cutting conditions include a radial direction cutting amount of the cutting tool in the radial direction. When the radial direction cutting amount in which one tooth is constantly in contact with the heat-resistant alloy is given as a smallest radial direction cutting amount and the radial direction cutting amount in which three or more teeth are not in contact with the heat-resistant alloy is given as a largest radial direction cutting amount, a radial direction cutting amount of the cutting tool is set in the range from the smallest radial direction cutting amount to the largest radial direction cutting amount.

A tool for machining a stacked material workpiece includes a tool body having one or more helical flutes extending to a forward end of the tool body. Each helical flute has a width defined by a first cutting edge and a second edge, a surface of the flute adjacent the first cutting edge facing the forward end of the tool body and a surface of the flute adjacent the second edge facing away from the forward end of the tool body. Each helical flute can include a first portion having a first negative pitch angle and a second portion having a second negative pitch angle different from the first negative pitch angle, the first portion extending from the forward end of the tool body to the second portion. The tool has only negative pitch angles. A method for machining a stacked material is also disclosed.

A hole is formed in an elbow through the steps of: forming a starting hole in a material, the starting hole having an undercut remaining on a hole surface; finishing an inner diameter of the starting hole (11.sub.-3) on one end side by revolving a side cutter (II) including an arc-shaped cutting edge and having an outer diameter smaller than a finishing hole diameter while rotating the side cutter (II) in such a posture that the side cutter (II) is inclined in a predetermined direction relative to the material (12), the revolving being carried out so that the side cutter moves along a hole surface to be finished; and finishing the inner diameter of the starting hole (11.sub.-3) on another end side by revolving the side cutter (II) while rotating the side cutter (II).

Provided is a cutter apparatus for machining a difficult-to-machine material, the cutter apparatus including: a cutting tool body which has a fastening portion formed at a center thereof; one or more cutters which are installed on the cutting tool body, and have superhard insert tips fixed to end portions thereof, respectively; and an angle adjusting unit which is installed in an internal space of the cutters, and adjusts angles of the cutters by spreading or retracting the cutters, so that angles of the cutters may be easily adjusted in accordance with a condition for cutting a difficult-to-machine material, in order to prevent damage to the superhard insert tips when machining a difficult-to-machine material having high hardness and high toughness.