CA1040407A

CA1040407A - Cutting tool and insert

Info

Publication number: CA1040407A
Application number: CA254,999A
Authority: CA
Inventors: Thomas W. Trendowski; Henry M. Schrier
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1975-06-30
Filing date: 1976-06-16
Publication date: 1978-10-17
Also published as: YU152476A; SE7607470L; IE42806L; IE42806B1; NO762219L; BE843558A; AT351335B; ES242128Y; ZA762662B; SE431725B; ES449066A1; AU1386376A; JPS5946721B2; FR2316031B1; ATA11977A; CH607756A5; SE431725C; ATA351476A; PL117607B1; JPS526184A

Abstract

ABSTRACT OF THE DISCLOSURE
A metal cutting tool with a disposable cutting insert is provided which is able to withstand heavy cutting forces which cause usual insert holding means to fail or freeze and inserts to fail. For heavy duty cutting, a solid cutting insert having cutting edges on its upper surface only with a recess which mates with a corresponding projection on the insert clamp is provided.

Description

1~ `
This invention relates to cutting tools having dis-posable inserts. More particularly, the invention relates to a cutting tool and insert which is especially adapted to withstand heavy cutting forces encountered in taking heavy cuts from metal work pieces.
Metal cutting tools having disposable cutting ; inserts are well known. Exemplary of such are metal cutting tools having a body or shank portion and a head or flank portion having a pocket or recess therein for the reception of disposable cutting inserts of various sizes and shapes having one or more cutting heads, such inserts being held in place as by means of a set screw inserted through a hole in the insert and extending through the lower pocXet surface into the flank portion. In some cases, insert seats are provided under the cutting insert, which latter can adjustably be held in place by clamping means as by the well known bridge or finger clamp, or simply by wedging means incorporated in the insert hole screw as illustrated, for example in U. S. patent 3,341,920 - W. H. Kelm -September 19, 1967: U. S. Patent 3,341,921 - E. J. Weller-September 19, 1967 and U. S. Patent 3,341,923 - W. H. Kelm -September 19, 1967. While prior art arrangements for holding cutting inserts have considerable merit, it has been found that they are lacking in holding power and resistance to the high forces generated in cutting metals on a massive scale wherein feeds of the order of 1/4 inch or more are use. It has been found, for example, that prior art clamping means tend either to fail under the cutting forces involved or tend to jam, making ready indexing of the insert overly time-consuming or even impractical or impossible. It is accordingly a primary objective of the present invention to provide a metal cutting tool and ..
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--1-- , 10404~)7 disposable insert particularly adapted to heavy metal cutting wark without physical failure and which, at the same time, lends itself to ready indexing or changing of the cutting edge presented to the work.
Those features of the invention which are believed to be novel are set forth with particularity in the claims appended hereto. The invention will, however, be better understood and further objects and advantages thereof appreciated from a consideration of the following descrip-tion and drawing in which Figure 1 is a plan view of an embodiment of the present invention, Figure la is a side elevational view of the embodiment and Figure lb is an elevational cross sectional view in the direction s-B of Figure 1.
Referring to the drawing, there i8 shown a metal cutting tool 1 having a body 2 partially shown which can be extended if desired. The cutting tool 1 also has a head or flank portion 3 having therein a recess or pocket 4 which is adapted to receive ahy particular shape of cutting insert such as square, round, octagonal, hexagonal, diamond and the like. The walls of pocket 4 are accurately machined ; and flat, the corners being usually stress relieved as ; at 5. Mounted in pocket 4 is cutting insert seat 6 head in place by an adjustable screw 7 threaded into hole 8 in the flank which can extend as desired and as shown through the flank. As is usual, the surfaces of seat 6 are accurately formed to fit snugly and tightly, mating against the bottom of pocket 4 and against the walls thereof more adequately to perform its purpose of transferring heat from the cutting edge and to spread cutting forces over the entire area of the pocket to prevent physical failure of and to protect and prolong the life of the , ,1~4~7 pocket. Mounted on insert seat 6 is cutting in~ert 9 which, as pointed out above, can take any of a number of configurations or shapes although that shown in an exemplary fashion is square. The insert 9 of the present invention is peculiar in a number of respects. For example, the insert has a flat bottom 10 and sides which are accurately formed or ground to mate with the corresponding surfaces of seat 6 and the walls of pocket 4. Where lighter duty inserts are indicated, they can, of course, be two-sided or have cutting edges on the upper and lower faces.
In~ert 9 is provided with the cutting edges 12 and as desired with chip breaking groove 13 which can take any of a number of desired forms which are well known to those skilled in the art. A particular feature of insert 9 is that for purposes of increased strength there are no holes bored therein for mounting purpose~. Instead, there is provided in the upper surface of the insert a recess 14 which, while ehown as being round, can take any of a number of shapes, such recess cooperating in discussed manner with clamp 15 which also can take any of a number of shapes but which is shown as of the usual bridge type having a body 16, partially recessed in flank 3, and arm or finger 17, the end 18 of which is shaped to mate with the recess 14 of insert 6 to hold the insert firmly in place. As shown, this end or projection 18 takes the form of a portion of a circle to mate with the arcuate rim of recess 14 although its shape can be varied to mate with the recesses 14 of any other desired shape. With the clamp tightened against insert 6, the mating end or projection 18 and recess 14 serve to hold the insert 9 firmly in place on insert seat 6 and against the walls of pocket 14.
The means for holding clamp 15 in place in flank 3 of the tool holder 1 is well known as illustrated, for example, in U. S. Patent 2,955,349 - H. E. York - October 11, 1960, but at the same time, in combination with the other desirable features of the present invention, serves to enhance the overall resistance to, and suitability for, heavy machining of metals. As shown in Figure lb, the clamp screw 19 extending through the body 16 has an upper portion 20 threaded in one direction in mating threaded hole 21 in clamp body 16, and a lower, oppositely threaded portion 23 threaded through the mating threaded hole 24 in flank 3.
Both the upper and lower ends of clamp screw 20 are typically provided with recessed heads for ready adjust-ment by means of a mating wrench. It will be seen that by turning the top portion 20 of set or clamp screw 19, clamp 15 can at one and the same time be loosened and lifted from its locking position on the tool holder. When the differential clamp screw 19 is tightened, such tightening serves to simultaneously lower the clamp 15 into position and to lock the cutter bit or insert 9 in place through the cooperation of projection 18 and recess 14.
As pointed out above, the present invention with its various salutary features and with its provision of a clamp 15 having a portion 18 which mates with a cooperating recess within the cutting bit or insert is particularly adapted to withstand the massive forces involved in removing large chip~ from metal work pieces.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A metal cutting tool having shank and flank portions, said flank portion having a pocket therein, said pocket having fixed therein a cutting insert seat comformably fitted to the walls of said pocket; a solid cutting insert having at least one cutting edge received on said seat and conformably fitted to the walls of said pocket; said insert having a flat lower surface and an arcuate planform recess in its upper surface, said arcuate recess having an upstanding rim intersecting said upper surface; a bridge clamp including a finger portion adjustably mounted on said flank, the finger portion when said clamp is tightened bearing upon and holding said cutting insert in place; a projection on said clamp finger, said projection having an arcuate shoulder portion complementary to at least a portion of said rim, so that said shoulder portion engages said rim as said clamp is tightened so as to retain said insert in close abutment with the walls of said pocket.

2. A metal cutting tool as in claim 1 wherein said insert recess is circular.

3. A heavy duty cutting insert having at least one cutting edge on the upper surface thereof, a flat bottom surface and a circular planform recess including an upstanding rim thereof intersecting said upper surface in said upper surface for cooperating with insert clamping means.

4. An insert as in claim 3 which additionally has chip breaking means.

5. An insert as in claim 3 or 4 when constructed from cemented tungsten carbide.