Cutting insert configuration

A cutting insert, especially for milling cutters or the like, which is receivable in a holder and which insert has linear edge portions which meet at the corners of the insert. The insert is indexable in the holder to present a selected edge to work to be done. Each of the edges of the inserts are serrated or notched with respective edges embodying different numbers of serrations or notches so that the inserts can be arranged in the holder to cut completely across a surface with each insert taking only a portion of the surface.

FIELD OF THE INVENTION 
Hard metal wafer-like inserts used in tool holders such as milling heads 
and boring cutters having serrated edges to reduce the cutting load with 
staggered teeth to produce full cut. 
BACKGROUND OF THE INVENTION 
Since the advent of indexable, wafer-like cutting inserts, sometimes 
referred to as throwaway inserts, there have been numerous disclosures of 
the use of sinusoidal or serrated edges on these inserts. This results in 
smaller chips and greatly reduced chip load. The cutters are arranged in a 
multiple blade rotating head so that they are staggered to insure a full 
cut of the material surface being removed, but each projection takes just 
a "nibble" at the workpiece. 
Examples of this type of insert are found in the United States patent to 
Owens, U.S. Pat. No. 3,636,602, dated Jan. 25, 1972, and to Malinchak, 
U.S. Pat. No. 3,875,631, dated Apr. 8, 1975. These cutters are 
particularly useful in roughing cuts. According to the present invention, 
a hard wear resistant cutting insert is provided which has faces on 
opposite sides facing in opposite directions and a peripheral surface 
extending between the faces. When viewed perpendicular to a face, the 
insert is polygonal, preferably, rectangular, and each edge of the insert 
between the respective corners is notched or grooved so that, when that 
particular edge of the insert engages a surface being worked, the regions 
of the edge between the notches or grooves will remove material from the 
workpiece while material will not be removed from the workpiece in the 
region of the notches or grooves. 
When two such inserts are arranged in tandem with one following the other 
in spaced relation, the second insert is arranged to remove those portions 
of the workpiece left by the preceding insert, and with this in mind, the 
several edges of the inserts have at least two different numbers of 
grooves formed therein so that a pair of inserts can be arranged in 
different indexed positions and the following insert will remove what is 
left on the workpiece by the preceding insert. 
In this manner, the holders for the inserts can be arranged to locate the 
inserts in a precise position by means of abutments and the insert clamped 
in the position and the inserts will be aligned to cooperate in the 
aforementioned manner. 
The present invention contemplates edges of inserts with different numbers 
of grooves or serrations in either opposed or adjacent edges so that when 
arranged seriatim, a full cut will be made. For example, if two opposed 
edges have four indentations to provide five (including the corners) 
cutting projections, then the other two opposed edges (of a square insert) 
can have three indentations to provide four cutting projections. These 
projections and indentations are spaced so the combined nine cutting 
projections in superimposed relation provide a full sweep of the 
workpiece. 
Thus, if there are "n" indentations or notches on one edge of an insert, 
there can be "n+m" notches on an adjacent edge to provide a full sweep of 
the work. 
This arrangement greatly simplifies the setting up of a milling cutter or 
the like in which the inserts are provided with grooves in the edges to 
distribute the cutting load between the inserts. 
Other objects and features of the invention will be apparent in the 
following description and claims in which the principles of the invention 
are set forth together with details to enable a person skilled in the art 
to practice the invention, all in connection with the best mode presently 
contemplated for the invention.

WITH REFERENCE TO THE DRAWINGS, in FIG. 1, a milling or boring head 10 is 
shown diagrammatically with a plurality of cutting inserts 20 and 22 
inserted in slots in the periphery and retained by conventional wedges or 
clamps (not shown). 
It will be seen that the insert 20 is presenting to the work an edge with 
four indentations and five cutting nibs, while insert 22 is presenting to 
the work an edge with three indentations and four cutting nibs or 
projections. 
As illustrated in FIG. 2, the insert 20 has the top and bottom edges 24 and 
26 with identical configurations while the adjacent edges 28 and 30 have 
identical configurations. Edges 24 and 26, which form the peripheral wall 
and which are perpendicular to the parallel polygonal faces 32 and 34 of 
the insert, have four indentations 36 while edges 28 and 30 forming the 
peripheral wall have three indentations. 
In FIG. 3, the insert 22 has an edge 30 presented in confrontation to edge 
26 of insert 20 of FIG. 2. The nibs or projections 40 of FIG. 2 register 
with the indentations 36 of FIG. 3 while the nibs or projections 42 of 
FIG. 3 register with the indentations 36 of FIG. 32. In FIG. 4, a view of 
the insert is shown presenting an edge showing the indentations 36 and the 
cutting projections or nibs 40. 
while FIG. 2 illustrates an insert with opposite edges identical, the 
insert could be made with adjacent edges identical so that opposite edges 
have different numbers of indentations and projections. The embodiment of 
FIG. 2 is preferred since a rotation of the insert either clockwise or 
counterclockwise will present a different edge and this simplifies 
installation and indexing. 
The inserts, as mentioned, can readily be indexed to present all of the 
edges thereof and can also be turned front to back so that each insert has 
eight effective edges that can be presented to the workpiece. 
Insert arrangements in which each insert takes a portion only of the 
surface being machined are known, but the insert of the present invention 
differs therefrom in that flat regions of substantial length are provided 
between adjacent ones of the notches or grooves formed in the periphery of 
the insert. In this manner, two only of the inserts are necessary to 
completely sweep a surface being machined. 
The importance of the notches or recesses in the periphery of the inserts 
will be appreciated in connection with the use of the insert in, for 
example, a milling cutter where the cutting action on each insert is 
interrupted and intermittent. Under these circumstances, it is preferable 
that the entire length of the cutting edge of an insert not be subjected 
to loading but, rather, only a portion thereof as the insert engages the 
work. 
While the particular embodiment of the insert according to the present 
invention has been shown and described having one side with four notches 
therein and an adjacent side with three notches therein, it will be 
understood by one of ordinary skill in the art that the number of notches 
can vary. For instance, the insert may have n notches on one side and n 
plus m notches as long as the numerals n and m stand for integers which 
are unequal. Thus, the number of notches on one side of the insert will 
always be unequal to the number of notches on an adjacent or opposite side 
of the insert. 
It has been found that a relatively smooth finish can be achieved with the 
present insert in which the edges of the cutting projections are 
relatively straight as distinguished from sinusoidal in contour. Thus, the 
effective cutting edges are straight and parallel to the general line of 
the cutting edge on which they are located. In addition, the relatively 
open contour of the indentations or notches prevents build up of chips 
which might lead to rubbing and scoring of the work and possible break 
down of the insert.