Cutters – for shaping – Rotary cutting tool – Including holder having seat for inserted tool
Reexamination Certificate
1999-04-20
2001-03-06
Tsai, Henry (Department: 3722)
Cutters, for shaping
Rotary cutting tool
Including holder having seat for inserted tool
C407S042000, C407S047000, C407S050000, C407S053000
Reexamination Certificate
active
06196769
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a cutting tool assembly having a replaceable insert for use in rotary machining operations in general and in finishing applications in particular.
BACKGROUND OF THE INVENTION
In known end milling cutters having indexable inserts, the inserts are arranged on the periphery of the tool and fastened thereto by means of clamping screws. When machining a surface whose height is greater than the height presented by the cutting edge of a single insert, an extended flute milling cutter is used whereby several inserts are arranged along the periphery of the tool in such an arrangement so as to effectively constitute a single long cutting edge.
The extended flute milling cutter, which is efficient for rough end milling operations, has several disadvantages when performing finishing operations: (i) radial mismatch between the inserts, on the same flute or on different flutes, causes unevenness of the machined surface, (ii) the angular pitch between the inserts decreases web thickness and thereby tool strength, (iii) the reliability of the entire tool depends on many components thereby increasing the chance for failure.
When performing finishing applications with tools having replaceable inserts at high speeds, e.g. in the range of 10,000 to 30,000 rpm, stability problems limits the use of conventional clamping systems.
In view of the foregoing, it should be apparent that there exists a need to provide a cutting tool that will eliminate, or reduce to within acceptable limits, the above mentioned problems and disadvantages.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a cutting tool assembly, rotatable about an axis of rotation A, comprising a tool, a replaceable insert mountable therein and at least one clamping screw, said tool comprises two substantially equal clamping jaws spaced apart by an insert receiving slot, each of said clamping jaws is provided with at least one screw bore and comprises a peripheral surface, peripheral abutment surface and central abutment surface, said peripheral abutment surface and said central abutment surface being substantially parallel to said axis of rotation,
said insert is of a generally prismatic shape having an axis of rotation B and comprising a central portion, a front surface, a rear surface, top and bottom surfaces having at least one through bore aligned with said at least one screw bore, and side surfaces on opposite sides of said axis of rotation, said side surfaces merging with said top and bottom surfaces at edges, at least one of said edges being a cutting edge,
each of said top and bottom surfaces comprising first and second abutting surfaces, each of said first and second abutting surfaces terminating in a front abutting portion having, respectively, central and peripheral front edge lines, and in a rear abutting portion having, respectively, central and peripheral rear edge lines, said peripheral front edge lines being parallel to said peripheral rear edge lines, and said central front edge lines being parallel to said central rear edge lines,
said first and second abutting surfaces of said top surface slope towards each other and inwardly towards the central portion of said insert and said first and second abutting surfaces of said bottom surface slope towards each other and inwardly towards the central portion of said insert.
There is also provided in accordance with the present invention an insert for clamping in a clamping tool between clamping jaws, said insert being of a generally prismatic shape having an axis of rotation B and comprising a central portion, a front surface, a rear surface, top and bottom surfaces and side surfaces on opposite sides of said axis of rotation, said side surfaces merging with said top and bottom surfaces at edges, at least one of said edges being a cutting edge,
each of said top and bottom surfaces comprising first and second abutting surfaces, each of said first and second abutting surfaces terminating in a front abutting portion having, respectively, central and peripheral front edge lines and in a rear abutting portion having, respectively, central and peripheral rear edge lines,
said first and second abutting surfaces of said top surface slope towards each other and inwardly towards said central portion of said insert and wherein said first and second abutting surfaces of said bottom surface slope towards each other and inwardly towards said central portion of said insert.
Preferably, said insert is thicker at its rear abutting portion than at its front abutting portion
Typically, said first and second abutting surfaces follow an elastic bending curve of said clamping jaws.
If desired, said first and second abutting surfaces are flat.
Preferably, said cutting edge follows a spiral path about the axis of rotation B.
Further preferably, said insert has two through bores.
Generally, said first and second abutting surfaces of said top surface are connected by a first intermediate surface and said first and second abutting surfaces of said bottom surface are connected by a second intermediate surface.
Preferably, said first and second intermediate surfaces are located on either side of a vertical plane V passing through the axis of rotation of the insert when the insert is oriented horizontally.
Further preferably, said first and second intermediate surfaces are located at equal distances from said vertical plane.
In accordance with one embodiment of the invention, said first and second intermediate surfaces are lines.
In accordance with another embodiment of the invention, said first and second intermediate surfaces have straight cross-sections in a plane perpendicular to the axis of rotation B.
In accordance with another embodiment of the invention, said first and second intermediate surfaces have curved cross-sections in a plane perpendicular to the axis of rotation B.
In accordance with the present invention, said peripheral and central abutment surfaces form between them an angle &agr;.
Further in accordance with the present invention, said first and second abutting surfaces of said insert top surface form between them an angle &agr;′ and wherein said first and second abutting surfaces of said insert bottom surface form between them an angle &agr;′.
Preferably, said angle &agr;′ is smaller than said angle &agr;.
If desired, said insert receiving slot terminates in an intermediate slot.
Further if desired, said intermediate slot terminates in a stress equalizing flexibilizing bore.
Preferably, said at least one through bore is provided in said top and bottom surfaces.
In accordance with one embodiment of the invention there is provided a cutting tool assembly rotatable about an axis of rotation A comprising a tool, a replaceable insert mountable therein and at least one clamping screw, said tool comprises two substantially equal clamping jaws spaced apart by an insert receiving slot having at least one rear abutment surface, each of said clamping jaws is provided with at least one screw bore slanted at an angle &dgr; with respect to a line perpendicular to the axis of rotation of the cutting tool assembly and having at least one screw bore tapered portion, each of said clamping jaws comprises a peripheral surface, peripheral abutment surface and central abutment surface, said peripheral abutment surface and said central abutment surface being substantially parallel to said axis of rotation;
said insert is of a generally prismatic shape having an axis of rotation B and comprising a central portion, a front surface, a rear surface, top and bottom surfaces having at least one through bore substantially aligned with said at least one screw bore, and side surfaces on opposite sides of said axis of rotation, said side surfaces merging with said top and bottom surfaces at edges, at least one of said edges being a cutting edge,
each of said top and bottom surfaces comprising first and second abutting surfaces, each of said first and second abutting surfaces terminating in a front abutting porti
Satran Amir
Weberman Yosef
Iscar Ltd.
Pennie & Edmonds LLP
Tsai Henry
LandOfFree
Cutting tool assembly and cutting insert therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cutting tool assembly and cutting insert therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cutting tool assembly and cutting insert therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2460241