CA2052669C - Metal cutting insert - Google Patents

Metal cutting insert

Info

Publication number
CA2052669C
CA2052669C CA 2052669 CA2052669A CA2052669C CA 2052669 C CA2052669 C CA 2052669C CA 2052669 CA2052669 CA 2052669 CA 2052669 A CA2052669 A CA 2052669A CA 2052669 C CA2052669 C CA 2052669C
Authority
CA
Canada
Prior art keywords
cutting
cutting edge
angle
nose
insert
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CA 2052669
Other languages
French (fr)
Other versions
CA2052669A1 (en
Inventor
Amir Satran
Gideon Boianjiu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Iscar Ltd
Original Assignee
Iscar Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Iscar Ltd filed Critical Iscar Ltd
Priority to CA 2052669 priority Critical patent/CA2052669C/en
Publication of CA2052669A1 publication Critical patent/CA2052669A1/en
Application granted granted Critical
Publication of CA2052669C publication Critical patent/CA2052669C/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B27/00Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
    • B23B27/14Cutting tools of which the bits or tips or cutting inserts are of special material
    • B23B27/141Specially shaped plate-like cutting inserts, i.e. length greater or equal to width, width greater than or equal to thickness
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2200/00Details of cutting inserts
    • B23B2200/20Top or side views of the cutting edge
    • B23B2200/201Details of the nose radius and immediately surrounding area

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)
  • Drilling Tools (AREA)

Abstract

A metal cutting insert for use in turning or drilling operations and having a rake surface and a pair of relief flanks merging in a nose of radius ? and defining with the rake surface a pair of cutting edges; each cutting edge having a first portion of length ? tangential with the corner, the first portion enclosing an angle ? and a second subsequent portion defining between them an angle .beta.; a chip former grouve being formed in the rake surface adjacent the cutting edges and the nose. The cutting edge is positive in the region of the nose and the first portions and the chip former groove adjacent thereto have a first portion which slopes towards a base of the insert, any chip deflecting portion thereof being sufficiently spaced from the cutting edge to allow for chips to have reached a desired minimal length prior to their deflection.

Description

- - 1 - 2052~69 This invention relates to a metal cutting insert for use in turning or drilling operations and is particularly concerned with such inserts for use in finishing operations.
It is well known with turning and drilling tools employing metal cutting inserts that the quality and precision of finish is a function of the tool geometry and machining conditions and, thereby the tool output. Thus, it is known that the higher the tool output, the lower the quality and precision of the finish. Thus, the cut surface tends to image to a greater or lesser degree the shape of the cutting edge of the tool insert or tip, this surface bearing a series of consecutive grooves. It is known to represent the quality of surface finish in terms of the mean depth h of these surface grooves and, as a first approximation, this mean surface depth Rt can be given by the relationship Rt = f2 8 x r where f is the feed of the cutting tool and r is the nose radius of the insert.
From this relationship, it can be readily seen that h decreases (and therefore the surface finish improves) with decreasing feed values and/or increasing nose radii.
It is, however, also well known that another factor which influences surface finish is the vibration induced in the tool by the cutting process. Thus, the surface finish is deleteriously affected by any increase in the vibration frequency and/or the amplitude of the vibrations. In this connection, it can be shown that the frequency and amplitude of the vibrations is directly related to the nature of the chip flow, in particular to the -frequency of breakage of the chips produced in the cutting operation. Because an increased frequency of chip breakage necessarily involves the production of shorter chips, the vibration frequency increases with the reduction in the length of the chips.
At the same time, it can be shown that the amplitude of the vibrations is mainly related to the cutting forces which are generated during the cutting operations, these cutting forces tending to increase with increasing depth of cut ap. On the other hand, it is known that with relatively low depths of cut such as those which occur during finishing operations, and especially with insert noses having a relatively large radii r, that the frequency of vibrations induced in the tool (Fr) tends to increase. Similarly, it is known that with tools where the angle of inclination of the cutting edge (0) is relatively low, there is also a corresponding increase in vibrational frequency Fr~
It will therefore be seen that the factors affecting the surface finish of the workpiece are numerous and the variation of one factor so as to improve the surface finish often carries with it a variation of another factor which tends to affect unfavorably the quality of surface finish.
It is therefore an object of the present invention to provide a new and improved cutting insert and a metal cutting tool incorporating such a cutting insert, in which the above-referred-to disadvantages are substantially reduced.
According to the present invention, there is provided a metal cutting insert for use in turning or drilling operations and having a rake surface and a pair of relief flanks merging in a nose of radius r and defining with said rake surface a pair of cutting edgesi at least one of said _ ~ 3 ~ 2052669 cutting edges having a first liner portion of length 1 tangential with said nose and a subsequent second linear portion the first portion of one cutting edge enclosing an angle ~ with a first corresponding portion of the other cutting edge, the second portion of said one cutting edge enclosing an angle with a second corresponding portion of the other cutting edge; a chip former groove being formed in said rake surface adjacent said cutting edges and said nose; a rake angle of said one cutting edge being substantially positive in the region of said nose and said first portion and the chip former groove adjacent thereto having a first portion which slopes towards a base of said insert, a chip deflecting portion being sufficiently spaced from the cutting edge to allow for chips to have reached a desired minimal length prior to their deflection and wherein 1 2 maximum feed fmax, (nominal value) and ~ is greater than ~.
Preferably the first corresponding portion is also of length 1 tangential with said nose.
With such a metal cutting insert and a metal cutting tool incorporating such an insert, while one of the cutting edges of the pair of cutting edges effects the actual cutting operation, the first cutting edge portions of the other cutting edge of the pair which is provided with a minimal relief angle with respect to the cut surface of the workpiece, effectively smoothes that cut surface so as to provide a good surface finish At the same time, by virtue of the provision of the particular chip former construction in the regions of the nose and the first cutting portions, it is ensured that the chips formed thereby flow with minimal resistance, thereby ensuring a reduction in the . ~

~ 4 ~ 2052 669 cutting forces and also ensuring that the chips produced are relatively long and, in consequence the frequency of chip breaking is reduced. Thus, this tends to result in a reduction of the vibrational frequency and also in the amplitudes thereof.
By virtue of this reduction of vibrational frequency and the amplitudes thereof, it is possible to allow for an increased feed without unduly affecting the quality of surface finish. With such an increased feed, the output can be significantly increased, and not necessarily at the expense of the surface finish.
For a better understanding of the present invention, and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:
Fig. 1 shows a side view of a metal cutting tool in accordance with the invention, in association with a workpiece;
Fig. 2 is a plan view from above of a metal cutting insert in accordance with the invention, incorporated in the metal cutting tool shown in Fig. li Fig. 3 is a cross-sectional view of the insert shown in Fig. 2, taken along the line III-III;
Fig. 4 is a view on an enlarged scale of a detail of a conventional insert of the same type as the insert shown in Fig. l;
Fig. 5 is a view on an enlarged scale of a detail A of the insert shown in Fig. 2;
Fig. 6 is a cross-sectional view taken along the line VI-VI of a portion of the insert shown in Fig. 2;
Fig. 7 is a schematic view of the cutting corner of an insert in accordance with the ~ 5 ~ 2052669 invention, positioned within a workpiece during a cutting operation;
Fig. 8 is a view on an enlarged scale of a detail B seen in Fig. 7; and Fig. 9 is a schematic view of a conventional insert and an insert in accordance with the invention superimposed on each other and located in position in a workpiece during a cutting operation.
As seen in Fig. l, a cutting tool l used for turning operations comprises a holder 2 in which is replaceably fitted an exchangeable cutting insert 3 which, in this embodiment, is of trigon shape.
The insert 3 is provided with two cutting edges 4 on each side (i.e. six cutting edges in all) and, as seen in the drawings, is used to turn a workpiece 5.
The insert 3 is located in the cutting tool 2 and so disposed with respect to the workpiece 5 that the cutting edge 4 thereof presents an angle of 0 inclination with respect to the workpiece surface.
As seen in Figs. 2 through 5 of the drawings, the insert is formed with a rake surface 7 and relief flanks 8, the cutting edges 4 being defined between the rake surface 7 and the relief flanks 8. A continuous chip former groove 9 extends around the insert adjacent the cutting edges 4.
Adjacent relief flanks 8 merge at a curved insert nose lO having a radius r.
As seen in Figures 2, 5, 7 and 8 of the drawings, each cutting edge 4 is formed of a first cutting edge portion 4a and a successive cutting edge portion 4b. The portions 4a define with each other an angle ~ while the portions 4b define with each other an angle ~ where ~ is slightly less than ~.

- 6 - 205 2~69 The first portions 4a of the cutting edges 4 are of length 1 which, as can be seen, is less than the length of the subsequent portions 4b.
Fig. 4 shows, for the sake of comparison, the corner portion of a standard insert of the same trigon shape, where the nose portion 10' has a radius r but where the entire adjacent cutting edges define an angle ~O.
Referring now to Fig. 6 of the drawings, it will be seen that the chip former groove 9 in the region of the nose 10 and the first cutting edge portions 4a comprises an initial land surface 15 which is positively disposed with respect to a base of the insert (not shown) at an angle ~ followed by a first portion of the chip former groove which slopes towards the base at an angle ~ and, at a relatively substantial distance from the nose, a deflector surface 16 of first portion of which defines an angle ~', with respect to the base and a second portion of which defines angle ~2 Representative ranges of the angles ~ ' and ~2 are 0-10 3-15, 0-5 and 0-45.
The chip former construction in the region of the nose and the first cutting edge portions 4a is chosen so that chips formed in this region reach a desired minimal length prior to their breakage.
In other words, the chips that become broken are relatively long chips and the frequency of breaking is therefore substantially reduced. In this way, it is ensured that vibrations induced in the cutting tool as a result of the chip breaking are of a relatively low frequency. At the same time, and in view of the fact that chips flow with minimal resistance over this chip forming region, the cutting forces exerted on the tool are significantly re~llcP~ and, in consequence, the amplitude of any vibrations which may be induced in the tool, is kept relatively low.
Thus, even with a relatively high feed it is possible to achieve a relatively high output and still have a very good quality of finish. Thus, e.g. with a feed rate as high as 0.8mm/rotation a value for Rt of l,um was obtained.
With a cutting insert as just described, and when incol~olated in a cutting tool 1 for the turning of a work-piece 5, as seen in Figs. 7 and 8 of the drawings whilst the first cutting edge portion 4a of one of the pair of cutting edges is used to effect turning of the workpiece, the other first cutting edge portion 4a or the other cutting edge of the pair is used to effect smoothing of the already turned surface. In order to ensure effective smoothing of this already turned surface, it is ~er~eS~ry to ensure that the first cutting edge portion 4a presents a relief angle ~ with respect to the turned surface which lies substantially within the range of 0.3 to 2.
In the embodiment just described, the cutting insert presents an angle of inclination ~ with respect to the surface to be turned, of about 90-95. Bearing in mind a relief angle ~ of between 0.3 to 2, it will be readily seen that the angle ~ lies in the range 90-83.
On the other hand, the subsequent cutting edge portions 4b define an angle ~ which is slightly less than the angle ~ and, in the example just described, the angle is equal to 80.
Fig. 9 shows clearly the differences between a co"ventional insert 21 shown in position on a workpiece to be turned and an insert in accordance with the invention 22 ; shown in the same position.

_ -- 8 With an insert and cutting tool in accordance with the present invention, the provision of the first cutting edge portions which define angles slightly greater than the angle of the subsequent cutting edge portions ensures an effective smoothing of the turned surface. On the other hand, the association of the insert with a chip former groove which allows for the relatively thin chips formed in a finishing operation to flow with minimal resistance and to be broken at a lower frequency rate, ensures that the vibra-tions i~u~ in the tool are kept relatively low, as isthe amplitude of these vibrations. In this way, the insert and the tool associated therewith are particularly effective in achieving a high degree of smoothness of a turned sur-face, esp~ci~lly during finishing operations.
Whilst in the embodiment specifically described above both of the cutting edges of the pair enclosing the nose are formed with tangentially directed first cutting edge portions of length 1, the invention is equally applicable where only one of the cutting edges of the pair is so formed.
Furthell.,ole the invention is equally applicable to insert shapes other than trigon such as for example rhombic, triangular etc.

Claims (4)

1. A metal cutting insert for use in turning or drilling operations and having a rake surface and a pair of relief flanks merging in a nose of radius r and defining with said rake surface a pair of cutting edges; at least one of said cutting edges having a first linear portion of length l tangential with said nose and a subsequent second linear portion the first portion of one cutting edge enclosing an angle .epsilon. with a first corresponding portion of the other cutting edge, the second portion of said one cutting edge enclosing an angle .beta. with a second corresponding portion of the other cutting edge; a chip former groove being formed in said rake surface adjacent said cutting edges and said nose; a rake angle of said one cutting edge being substantially positive in the region of said nose and said first portion and the chip former groove adjacent thereto having a first portion which slopes towards a base of said insert, a chip deflecting portion being sufficiently spaced from the cutting edge to allow for chips to have reached a desired minimal length prior to their deflection and wherein l ? maximum feed fmax, (nominal value) and .epsilon. is greater than .beta..
2. A metal cutting insert according to claim 1, wherein l is substantially equal to fmax (nominal value).
3. A metal cutting insert according to claim 1, wherein said cutting edge first portion and said nose are associated with a land surface which slopes towards said insert base at an angle .gamma. and wherein said chip former groove first portion slopes towards said base at an angle .lambda., wherein .gamma. lies sub-stantially in the range 0° to 10° and .lambda. lies sub-stantially in the range 3° to 15°.
4. A metal cutting tool comprising a tool holder and a metal cutting insert according to claim 1 releasably held therein, wherein one said first cutting edge portion is designed to present an angle of cutting inclination .theta. and the other of said first cutting edge portions is designed to present a relief angle .PHI. wherein .PHI. lies substantially within the range 0.3° to 2°, so that .epsilon. substantially equals 180°-(.theta.+.PHI.).
CA 2052669 1991-10-02 1991-10-02 Metal cutting insert Expired - Lifetime CA2052669C (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA 2052669 CA2052669C (en) 1991-10-02 1991-10-02 Metal cutting insert

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA 2052669 CA2052669C (en) 1991-10-02 1991-10-02 Metal cutting insert

Publications (2)

Publication Number Publication Date
CA2052669A1 CA2052669A1 (en) 1993-04-03
CA2052669C true CA2052669C (en) 1995-10-24

Family

ID=4148495

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2052669 Expired - Lifetime CA2052669C (en) 1991-10-02 1991-10-02 Metal cutting insert

Country Status (1)

Country Link
CA (1) CA2052669C (en)

Also Published As

Publication number Publication date
CA2052669A1 (en) 1993-04-03

Similar Documents

Publication Publication Date Title
US5226761A (en) Metal cutting insert and metal cutting tool utilizing the metal cutting insert
US4215957A (en) Cutting insert for chipforming machine
JP4489874B2 (en) Cutting tips for machining to form chips
EP0313534B1 (en) Method for chip removing machining
EP0480576B1 (en) An insert for a milling cutter
EP0046874B2 (en) Cutting insert
JP4603550B2 (en) Cutting insert for high speed feed face milling
EP0464825B1 (en) Throwaway insert and cutting tool therefor
JP3923678B2 (en) Cutting tip
EP0775544B1 (en) Cutting insert for grooving and for the widening of grooves
CA2332285C (en) Cutting insert for grooving
JP3090325B2 (en) Rotary milling
KR100387406B1 (en) Cutting insert with curved cutting edge
US4776733A (en) Cutting tool
US5085542A (en) Indexable cutting insert
EP0747156B1 (en) Cutting insert and cutter for milling
US6802676B2 (en) Milling insert
US5810520A (en) Tool for material-removing machining
JP3769020B2 (en) Cutting insert
US5964552A (en) Method and cutting insert for cutting screw threads in metal work pieces
EP0205977A2 (en) Cutting insert with chip control
US3781956A (en) Cutting insert
US5755536A (en) indexable cutting insert
EP3059037A1 (en) Double-sided high feed milling insert, high feed milling tool and method
JP2002536197A (en) Cutting inserts for turning

Legal Events

Date Code Title Description
EEER Examination request
MKEX Expiry