EP0506238A2
Expired / Lapsed
EP
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Composite cutting insert
Assignee: De Beers Industrial Diamond Division Pty Ltd
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Filing: 1992-02-28
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Granted: —
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Expires: 2012-02-28
Abstract
Abstract A method of producing a composite cutting insert for a twist drill includes the steps of cutting an intermediate blank (16) from a composite diamond compact (10). The intermediate blank comprises a relatively broad tungsten carbide strip (20) with a relatively narrow polycrystalline diamond strip (18) at one edge. First and second cutting insert halves (22.1, 22.2) are cut from the intermediate blank, each cutting insert half defining a cutting edge (26, 28) of the diamond material. The cutting insert halves are arranged back-to-back to form a composite cutting insert (24), with the cutting edges on opposite sides of a central plane (A-A). The cutting edges are arranged to define a chevron shaped composite cutting edge. The cutting insert halves are preferably brazed together to form a unitary cutting insert. The invention extends to a method of producing a twist drill including the steps of forming a slot-shaped seat (30) diametrally in the end of a twist drill body, and brazing the composite cutting insert into the seat.
Inventors
- 👤 Mohammad Najafi Sani
- 👤 Graeme David Dufferwiel
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 11:59
CPC Classifications
B; B23; B23P; B23P15/00; B23P15/28; B23P15/32; B23P5/00; B23B; B23B27/00; B23B27/14; B23B27/141; B23B27/145; B23B27/148; E; E21; E21B; E21B10/00; E21B10/46; E21B10/58; B23B2222/00; B23B2222/28; B23B2226/00; B23B2226/31; B23B2226/315; Y; Y10; Y10S; Y10S76/00; Y10S76/11; Y10S76/12; Y10T; Y10T408/00; Y10T408/78; Y10T408/81
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
78 words
A method of producing a composite cutting insert characterised in that it includes the steps of: forming first and second cutting insert halves (22.1, 22.2) from a composite diamond compact blank (10), each cutting insert half defining a cutting edge (26, 28) of diamond material; and arranging the cutting insert halves back-to-back to form a composite cutting insert (24), so that the respective cutting edges lie on opposite sides of a central plane (A-A) of the composite insert.
Claim 2
Dependent Claim
31 words
A method according to claim 1 characterised in that it includes the step of bonding the two cutting insert halves (22.1, 22.2) together to form a unitary composite cutting insert (24).
Claim 3
Dependent Claim
26 words
A method according to claim 2 characterised in that the cutting insert halves (22.1, 22.2) are brazed together to form the unitary composite cutting insert (24).
Claim 4
Independent Claim
57 words
A method according to any one of claims 1 to 3 characterised in that the cutting insert halves (22.1, 22.2) are formed with a rectangular cross section, so that the composite cutting insert (24) has a rectangular cross section and is adapted for insertion into a diametral slot-shaped seat (30) in the end of a twist drill.
Claim 5
Independent Claim
36 words
A method according to any one of claims 1 to 4 characterised in that the respective cutting edges (26, 28) of the cutting insert halves (22.1, 22.2) are arranged to define a chevron-shaped composite cutting edge.
Claim 6
Independent Claim
80 words
A method according to any one of claims 1 to 5 characterised in that the method includes the steps of cutting a strip from a composite diamond compact disc (10) to form an intermediate blank (16) having a strip of diamond material (18) at one edge thereof, and cutting the cutting insert halves from the intermediate blank so that the cutting edge (26, 28) of each cutting insert half (22.1, 22.2) is formed from a portion of the diamond strip.
Claim 7
Dependent Claim
33 words
A method according to claim 6 characterised in that the intermediate blank (16) comprises a relatively broad tungsten carbide strip (20) with a relatively narrow polycrystalline diamond strip (18) at one edge thereof.
Claim 8
Independent Claim
45 words
A method according to any one of claims 1 to 7 characterised in that the respective cutting edges (26, 28) of the cutting insert halves (22.1, 22.2) are arranged so that they overlap in a zone defining the chisel edge of the finished twist drill.
Claim 9
Dependent Claim
21 words
A composite cutting insert characterised in that it is formed by the method of any one of claims 1 to 8.
Claim 10
Dependent Claim
45 words
A method of producing a twist drill characterised in that it includes the steps of: providing a composite cutting insert (24) according to claim 9; and fixing the composite cutting insert into a seat (30) formed diametrally in the end of a twist drill body.
Claim 11
Dependent Claim
27 words
A method according to claim 10 characterised in that the composite cutting insert is a unitary insert (24) which is fixed into the seat (30) by brazing.
Claim 12
Dependent Claim
34 words
A method according to claim 11 characterised in that the composite cutting insert (24) comprises two cutting insert halves (22.1, 22.2) which are simultaneously bonded together and fixed into the seat (30) by brazing.
Claim 13
Independent Claim
40 words
A method according to any one of claims 10 to 12 characterised in that the geometry of the twist drill flute and tip is restored by grinding after the composite cutting insert (24) has been fixed into the seat (30).
Claim 14
Dependent Claim
24 words
A method according to claim 13 characterised in that less than 50% of the portion of the insert (24) which is ground comprises diamond.
Claim 15
Dependent Claim
20 words
A twist drill characterised in that it is formed by the method of any one of claims 10 to 14.
References Cited (Backward Citations)
No citation records indexed.
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