Cutting insert

Details Cutting insert Cutting insert

1999-06-10

2001-03-06

Bishop, Steven C. (Department: 3722)

Cutting by use of rotating axially moving tool

Tool or tool with support

Having peripherally spaced cutting edges

C407S040000, C407S107000, C408S713000

Reexamination Certificate

active

06196774

ABSTRACT:

FIELD
This invention relates to cutting inserts for reamers and borers and to a method of securing a cutting insert to a reamer or borer.
BACKGROUND OF THE INVENTION
Borers are used for finishing holes already formed in parts and generally comprise an elongate body having a cutting blade or insert housed in a groove in the end of the body. The other end of the body may be tapered to engage a machine tool spindle.
The cutting blade or insert may be held in the groove by means of a clamping plate of the type described in U.S. Pat. No. Re. 34,054, or may be held in position by means of clamping screws, the heads of which clamp the insert against the borer body as the screw is tightened, as is shown in EP 0650 792-A. This document discloses a reamer in which the screw head has a front surface that is convex and engages in a longitudinally extending concave groove in the surface of the insert. Such a locking system locates and holds the insert against transverse movement but does not locate and hold the insert longitudinally. The insert is typically located by abutment of one end face against a stop pin in the groove.
OBJECT OF THE PRESENT INVENTION
The present invention provides a cutting insert or blade which is located and held along two axes by the clamping screws.
STATEMENTS OF INVENTION
According to the invention there is provided a cutting insert for a borer or reamer comprising a flat blade having a front face with at least one cutting edge thereon, the front surface having at least one dimple, or depression, having two clamping faces therein which are frustoconical and extend parallel to the cutting edge, the depression changing in depth longitudinally, and preferably having a base with an arcuate longitudinal cross-section.
The blade is preferably a rectangular blade, which term includes a square blade, having an elongate cutting edge.
By longitudinal is meant along a direction which is in use parallel to the axis of rotation of the borer or reamer.
Because the clamping faces are frustoconical, the depression also changes continuously in depth outwardly from a maximum depth along the transverse cross section and the depression has a shallow “V’ shaped transverse cross section. Preferably the included angle between the two sides of the depression is between 160 and 170 degrees of arc, preferably about 166 degrees.
Also according to the invention there is provided a reamer or borer having a body with an axially extending cavity therein that receives a cutting insert according to the above invention and has at least one screw fastener that engages in a co-operating threaded hole in the body and which has a head which engages a clamping face in the depression to clamp the insert into the cavity.
Preferably the frustoconical portion of the head has different diameters to the frustoconical clamping faces.
The screws are preferably left handed screw threads and the head of the screw has a frustoconical portion that engages in the depression. Since the depth of the depression changes along two axes the frustoconical surface bites into the base of the depression and fictionally engages the surface of the base to hold the blade against movement along two orthogonal axes.
Yet another aspect of the invention provides a method of assembling a cutting insert into a reamer or borer having an axially extending cavity to receive the insert and a screw fastener which engages in a hole in the reamer or borer and has a fastener head which engages in a depression, or dimple, in a surface of the insert when the screw is tightened, the fastener head having a frustoconical portion which engages a respective frustoconical clamping face in the depression to hold the insert against movement along at least two orthogonal axes.


REFERENCES:
patent: 3754309 (1973-08-01), Jones et al.
patent: 4477212 (1984-10-01), Kraft
patent: 4697963 (1987-10-01), Lück
patent: 5494383 (1996-02-01), Kress et al.
patent: 5597270 (1997-01-01), Marin
patent: 4202295 (1993-06-01), None
patent: 1468529 (1967-02-01), None
patent: 891231 (1981-12-01), None

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