Chip forming insert, especially for turning and slotting

Details Chip forming insert, especially for turning and slotting Chip forming insert, especially for turning and slotting

1994-03-17

1995-01-17

Terrell, William E.

Cutters, for shaping

With chip breaker, guide or deflector

Comprising concave surface in cutting face of tool

407117, B23B 2708, B23B 2722

Patent

active

053821190

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Technical Field of the Invention
This invention relates to cutting bits or inserts for cutting work especially turning wherein the insert is detachably held in a tool holder of a lathe or similar machining apparatus.
2. Description of the Prior Art
Within the technical field is known a cutting bit insert which adjacent to the cutting edge presents a recess, down into which the middle portion of the chip is pressed during the machining operation. The side portions of the insert are kept in a somewhat higher plane in order to give the chip a lateral bending so that it will have less width than it has just upon leaving the cutting edge and thereby becomes narrower than the groove cut. The laterally bent chip can then roll itself and form a coil, which is narrower than the turned groove and does not causes damage to the machined surfaces or the like.
Within this field, it is also known to arrange, remote from the cutting edge of any tool, a chip breaker, that is a protruding portion which will be engaged by the cut chip in order to be guided away abruptly. This results in a breaking of the chip preventing it from forming continuous coils, spirals or spools which in turn might cause tool damages or damage to the work piece and machined surfaces. However, in this arrangement the chip is subjected to deformation during the breaking off process which increases its lateral width and tends to cause congestion of chips and poor surface finish on the side surfaces of the groove.
One essential aspect of this invention is to provide a new cutting insert that causes lateral bending of the chip and also causes it to break thereby producing short chips having less width than the groove cut. Such chips being easily removed from the groove without tendency to adhere to the sides of the groove, the tool or the like.


SUMMARY OF THE INVENTION

The cutting insert according to the present invention has projections downstream of the cutting edge, in the direction of movement of the chip, to guide the chip away from the planar surface adjacent the cutting edge and act as chip breaker. The projections being arranged laterally remote from each other. Between the projections adjacent the cutting edge, is a concave middle recess having obliquely arranged and concave surfaces along its sides.
A chip cut from a work piece slides inwardly over the middle recess arranged adjacent the cutting edge and is thereupon subjected to an initial lateral bending as the portion of the chip still attached to the work piece presses the free portion of the chip against the surface adjacent the cutting edge. Simultaneously, the edge flanks of the chip are guided by the side portions of the planar surface on either side of the recess toward the projections. The force the chip still attached to the work piece by an intermediate portion and pushed forwardly thereby to bend upwardly so the chip portion between the projections eventually leaves the bottom of the middle recess and floats freely between the projections. With the chip then heavily deformed both in its length and lateral directions, the chip will break beyond the top portions of the projections and form laterally bent or arched and lengthwise curved short chip pieces having smaller width than the groove cut by the cutting edge.


BRIEF DESCRIPTION OF THE DRAWING

The above as well as other features and advantages of the invention will be apparent through consideration of the detailed description in connection with the several drawings in which:
FIG. 1 is a side elevational view showing a cutting insert according to the invention,
FIG. 2 is a front elevational view of the same insert,
FIG. 3 is a top plan view of the cutting insert, and
FIG. 4 is a cross-sectional view taken along the line C--C of FIG. 3.


DETAILED DESCRIPTION OF THE INVENTION

The cutting insert 1, the main features of which essentially correspond to those of a known insert, has a V-shaped bottom ridge 2 and an upper abutment surface 3. The V-shaped bottom ridge 2 is intended to cooperate with a

REFERENCES:
patent: 4583887 (1986-04-01), Wertheimer
patent: 4957396 (1990-09-01), Niebauer
patent: 4973204 (1990-11-01), Mihic

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