Abstract: In order to perform turning operations of the kind that has heretofore been performed by diamond-shaped inserts, an insert which is basically equilateral triangular in shape with multiple alternately usable cutting edges, of which all three corners are usable as cutting edges, without decreasing the positional accuracy of the cutting edge during cutting. At least one recess and a plurality of protrusions are formed on each side of the insert. The recess and protrusions formed on the insert are brought into engagement with a protrusion and recesses formed on a side wall of a seating groove formed in a holder. In this state, the insert is pressed against a bottom seating face and the side wall of the seating groove with a clamp as a means to stably restrain the insert. This prevents shifting of the cutting edge during cutting even if the direction of the cutting force changes.

Abstract: An indexable insert has a rake face on which a first ridge (2) and a second ridge (3) are provided. The first ridge (2) protrudes from a boss surface (1) towards a nose, and the second ridge (3) extends continuously from the first ridge (2) to a slope (8) connected to a cutting-edge land (7) of a linear cutting edge (6). The second ridge (3) has a height lower than that of the first ridge (2) and is convex-curved towards a bisecting line (CL) of an apex angle of the nose in plan view, thereby achieving both enhanced chip processability and reduction of load received when raking a chip.

Abstract: An object is to provide a vibration suppressing cutting tool which is inexpensive and can damp chattering extremely effectively, and which is simple in structure and is applicable to a wide variety of machining diameters and cutting conditions. The shank 2 of the holder 1 is formed with a pocket 4. In the pocket 4, a vibration suppressing piece 5 is received so as to be movable relative to the holder 1 and not protrudable from the pocket 4. Under kinetic energy from the holder during cutting, the vibration suppressing piece 5 alternately knocks against a pair of opposed inner wall surfaces 4a and 4b of the pocket along its surface, along a plurality of lines or on a plurality of points when the holder vibrates during cutting, thereby damping vibrations of the holder.

Abstract: An indexable insert has a rake face on which a first ridge (2) and a second ridge (3) are provided. The first ridge (2) protrudes from a boss surface (1) towards a nose, and the second ridge (3) extends continuously from the first ridge (2) to a slope (8) connected to a cutting-edge land (7) of a linear cutting edge (6). The second ridge (3) has a height lower than that of the first ridge (2) and is convex-curved towards a bisecting line (CL) of an apex angle of the nose in plan view, thereby achieving both enhanced chip processability and reduction of load received when raking a chip.

Abstract: A holder 1 has a shank portion 2 provided with a pocket 4 having the shape of a nearly rectangular solid. The pocket 4 is placed at a position relatively close to the tip of the tool. In the cross section of the shank, the pocket 4 has a width of 50% to 100% of the shank diameter or width, a height of 20% to 50% of the shank height, and a length of 50% to 250% of the shank diameter or height. A weight 5 is inserted into the pocket 4 such that the weight is movable but unable to rush out. The weight 5 has the shape of a nearly rectangular solid and is made of a material having a specific gravity comparable to or greater than that of the material of the shank portion.

Abstract: An object is to provide a vibration suppressing cutting tool which is inexpensive and can damp chattering extremely effectively, and which is simple in structure and is applicable to a wide variety of machining diameters and cutting conditions. The shank 2 of the holder 1 is formed with a pocket 4. In the pocket 4, a vibration suppressing piece 5 is received so as to be movable relative to the holder 1 and not protrudable from the pocket 4. Under kinetic energy from the holder during cutting, the vibration suppressing piece 5 alternately knocks against a pair of opposed inner wall surfaces 4a and 4b of the pocket along its surface, along a plurality of lines or on a plurality of points when the holder vibrates during cutting, thereby damping vibrations of the holder.

Abstract: In order to perform turning operations of the kind that has heretofore been performed by diamond-shaped inserts, using a triangular insert with multiple alternately usable cutting edges, of which all three corners are usable as cutting edges, without lowering the positional accuracy of the cutting edge during cutting, according to the present invention, at least one V-shaped recess 5 and a plurality of V-shaped protrusions 6 are formed on each side of an insert 1 which is basically equilateral triangular in shape. The recess 5 and protrusions 6 are brought into engagement with a V-shaped protrusion and V-shaped recesses 18 formed on a side wall 12b of a seating groove formed in a holder 11. In this state, the insert 1 is pressed against a bottom seating face and the side wall of the seating groove with a clamp means to stably restrain the insert. This prevents shifting of the cutting edge during cutting even if the direction of the cutting force changes.

Abstract: A holder 1 has a shank portion 2 provided with a pocket 4 having the shape of a nearly rectangular solid. The pocket 4 is placed at a position relatively close to the tip of the tool. In the cross section of the shank, the pocket 4 has a width of 50% to 100% of the shank diameter or width, a height of 20% to 50% of the shank height, and a length of 50% to 250% of the shank diameter or height. A weight 5 is inserted into the pocket 4 such that the weight is movable but unable to rush out. The weight 5 has the shape of a nearly rectangular solid and is made of a material having a specific gravity comparable to or greater than that of the material of the shank portion.

Abstract: A wheelchair has actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the user's weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight. A brake is mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction. Levers are coupled directly or indirectly to the brake to move according to descending motions of the actuation plates to put the brake in a non-braking state and to move according to ascending motions of the actuation plates to put the brake in a braking state. Biasing devices for evacuating legs that extend from the seat and/or steps that are mounted onto the legs.

Abstract: A wheelchair has actuation plates provided in juxtaposition with the seat to descend when a user sits on the seat to lower the seat with the weight and to ascend when the user rises from the seat to permit the seat to return with removal of the weight, brake means mounted on the axle shafts to brake the axle shafts and energized constantly in a non-braking direction, and levers coupled directly or indirectly to the brake means to move according to descending motions of the actuation plates to act on the brake means to put the brake means in a non-braking state and to move according to ascending motions of the actuation plates to act on the brake means to put the brake means in a braking state.

Abstract: An indexable insert with a chip breaker configured such that chips produced under various cutting conditions from rough cutting to finish cutting can be disposed of in an optimum way. Protrusions are provided in a chip breaker groove to extend from a central land toward the respective corners of the insert. Each protrusion has a breaker wall which is concave and curved such that chips produced always collide against the breaker wall at an angle of 10.degree.-40.degree. so that the chips are curled helically with a helix angle of 10.degree.-40.degree. and broken into small pieces reliably.

Abstract: A throw-away insert for low-depth-of-cut finish cutting can be used over a wide range of feed rates. A breaker groove is provided between the center land and each cutting edge. An arcuate small protrusion is formed on the bisector of each nose portion. A narrow groove is formed in the small protrusion. Thin chips, which are produced while the feed rate is low, are curled and broken by the groove formed in the protrusion. Thick chips, which are produced while the feed rate is high, are guided along the grooves and collide with an edge of a side wall of the center land. Thus, thick chips are also smoothly curled and broken by the edge.