Cutters – for shaping – Including tool having plural alternatively usable cutting edges
Reexamination Certificate
1999-11-18
2001-09-25
Wellington, A. L. (Department: 3722)
Cutters, for shaping
Including tool having plural alternatively usable cutting edges
C407S046000, C407S040000
Reexamination Certificate
active
06293737
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an indexable cutting insert for mounting on a milling cutter for use in such operations as face and end milling, square shoulder milling, plunger milling and the like and, particularly, to the arrangement of an axial support of such a cutting insert in the milling cutter.
BACKGROUND OF THE INVENTION
Indexable cutting inserts used in milling cutters of the above-specified kind are often of a generally quadrangular shape and have two pairs of opposite peripheral and front cutting edges defining therebetween at least two indexable cutting corners. The cutting insert is mounted on a milling cutter so as to present an operative cutting corner associated with a peripheral cutting edge substantially co-directional with a longitudinal axis of the milling cutter and its adjacent front cutting edge substantially transverse thereto. When the cutting insert is mounted at a leading end of the milling cutter, for cutting operations of the kind specified above, with both peripheral and front cutting edges being operative, the insert needs to be provided with both axial and radial supports. To this end, insert receiving pockets formed at leading ends of milling cutters' bodies usually have an axially supporting side wall perpendicular to the pocket's base surface and substantially co-directional with the longitudinal axis of the milling cutter body, and a radially supporting side wall perpendicular to the pocket's base surface and extending radially with respect to the longitudinal axis. The axially and radially supporting walls of the insert receiving pocket meet at an innermost corner region thereof which is designed so as to receive therein an inoperative cutting corner of the cutting insert.
When a milling cutter of the above kind has an extended flute with a plurality of cutting inserts mounted therealong to form a continuous cutting line, such as for example in U.S. Pat. No. 5,083,887, the necessity to provide the cutting inserts, or at least the ones mounted at a leading end of the cutter, with the axially supporting wall, has a disadvantage in that this axially supporting wall hinders the development of chips formed by another cutting insert disposed adjacent this wall.
To avoid the use of an axially supporting wall in an insert receiving pocket designed for carrying cutting inserts mounted at a leading end of a milling cutter, the pocket is sometimes provided with a pin located adjacent an innermost corner of the pocket and protruding from the radially supporting side wall thereof. This pin is adapted to abut a radially innermost portion of the cutting insert's side surface associated with an inoperative front cutting edge thereof.
However, the above arrangement is not suitable for cases when cutting inserts of different geometries of cutting corners are to be mounted in the same insert receiving pocket. For example, a cutting insert having a cutting corner of relatively large radius cannot be supported by a pin designed to abut a cutting insert having a cutting corner of relatively small radius.
It is an object of the present invention to provide a new cutting insert and a new arrangement of its axial support in a milling cutter which, inter alia, have advantages in the above respect.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a cutting insert for mounting on a milling cutter;
said cutting insert being of a generally quadrangular shape and having top and bottom surfaces, a pair of opposite first side surfaces intersecting said top surface at first cutting edges and a pair of opposite second side surfaces intersecting said top surface at second edges each having a front cutting portion oriented substantially transversely to an adjacent first cutting edge and meeting therewith via a cutting corner;
each of said first and second side surfaces having upper and lower sections adjacent respective top and bottom surfaces, which sections have leading portions adjacent their associated cutting corner and trailing portions remote therefrom, the trailing portion of the lower section of each second side surface being at least slightly inwardly depressed relative to the leading portion of said lower section and being substantially inwardly depressed relative to the associated trailing portion of the upper section of said second side surface, the trailing portions of the lower and upper sections merging via a transition surface oriented transversely thereto.
The design of the second side surfaces in the cutting insert according to the present invention enables the use of the trailing portion of its lower section for an axial support of the cutting insert when mounted in an insert receiving pocket of a tool holder, whereby the axial support is arranged at a region of an inoperative side surface which is remote from the cutting insert's inoperative cutting corner, and in a manner which does not require additional space in the axial direction of the tool holder.
Therefore, the design of the axial support arrangement does not depend on the geometry of the cutting insert's cutting corners, whereby cutting inserts having different cutting corner geometries may be supported by one and the same insert receiving pocket of a tool holder.
Preferably, the trailing portion of the upper section of each second side surface extends outwardly from its associated second cutting edge towards the lower section thereof. By virtue of this, the trailing portion of the lower section of the cutting insert's second side surface may be depressed inwardly to the extent required for the axial support without essential reduction of the area of the bottom surface of the cutting insert. It is still more preferable in this case that the upper sections of the first side surfaces of the cutting insert also slope generally outwardly from their associated cutting edges in the direction of the cutting insert's bottom surface, whereby the first cutting edges of the cutting insert are provided with a strengthened cutting edge.
If desired, the leading portion of the lower section of each second side surface is depressed relative to the leading portion of the upper section thereof.
It should be mentioned here that a cutting insert having a depressed lower section of second side surfaces combined with upper sections of side surfaces extending outwardly from the insert top surface in the direction of the insert bottom surface is disclosed in WO 98/07541. However, the lower section there does not serve for the axial support of the cutting insert and the extent of its depression increases towards the leading region of the lower section associated with an inoperative cutting corner, which is contrary to the present invention.
The cutting insert according to the present invention is designed for use in a milling cutting comprising a tool holder which has a longitudinal axis and is formed with an insert receiving pocket for mounting therein the cutting insert of the present invention so as to present a substantially axially directed operative first cutting edge. The insert receiving pocket has a base surface of a shape generally corresponding to the shape of the bottom surface of the cutting insert, a radially supporting wall co-directional with said axis for interacting with the first side surface of the cutting insert associated with the inoperative first cutting edge, and an axially supporting element protruding upwardly from said base surface at a radially outermost and axially furthermost corner thereof, for interacting with the trailing portion of the lower section of the inoperative second side surface; said axially supporting element being designed to be substantially fully received in the area of the trailing portion of the lower section of the second side surface, the axially supporting element having a contact surface adapted to interact with said trailing portion.
To the above end, maximal dimensions of said axially supporting element in its cross-section perpendicular to the longitudinal axis are smalle
Satran Amir
Smilovici Carol
Zeira Ilana
Ergenbright Erica D.
Iscar Ltd.
Pennie & Edmonds LLP
Wellington A. L.
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