WO2019166133A1 - Plaquette de coupe indexable - Google Patents

Plaquette de coupe indexable Download PDF

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Publication number
WO2019166133A1
WO2019166133A1 PCT/EP2019/025058 EP2019025058W WO2019166133A1 WO 2019166133 A1 WO2019166133 A1 WO 2019166133A1 EP 2019025058 W EP2019025058 W EP 2019025058W WO 2019166133 A1 WO2019166133 A1 WO 2019166133A1
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WO
WIPO (PCT)
Prior art keywords
face
main
faces
indexable cutting
cutting insert
Prior art date
Application number
PCT/EP2019/025058
Other languages
English (en)
Inventor
John James Barry
Original Assignee
John James Barry
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 John James Barry filed Critical John James Barry
Publication of WO2019166133A1 publication Critical patent/WO2019166133A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
    • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
    • B23B27/141—Specially shaped plate-like cutting inserts, i.e. length greater or equal to width, width greater than or equal to thickness
    • B23B27/145—Specially shaped plate-like cutting inserts, i.e. length greater or equal to width, width greater than or equal to thickness characterised by having a special shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2200/00—Details of cutting inserts
    • B23B2200/04—Overall shape
    • B23B2200/0404—Hexagonal
    • B23B2200/0419—Hexagonal trigonal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2200/00—Details of cutting inserts
    • B23B2200/04—Overall shape
    • B23B2200/0447—Parallelogram
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2200/00—Details of cutting inserts
    • B23B2200/04—Overall shape
    • B23B2200/0471—Square
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2200/00—Details of cutting inserts
    • B23B2200/36—Other features of cutting inserts not covered by B23B2200/04 - B23B2200/32
    • B23B2200/369—Mounted tangentially, i.e. where the rake face is not the face with the largest area
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2226/00—Materials of tools or workpieces not comprising a metal
    • B23B2226/12—Boron nitride
    • B23B2226/125—Boron nitride cubic [CBN]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2226/00—Materials of tools or workpieces not comprising a metal
    • B23B2226/18—Ceramic

Definitions

  • indexable cutting inserts of hard cutting materials which may be held in a tool holder and which may be used for turning, milling and other chip- forming or machining processes.
  • Indexable cutting inserts may be held in at least one of six to fourteen possible positions in the tool holder and are characterised by at least two substantially parallel polygonal faces between which are several inclined or curved faces.
  • PCBN cutting tools and indexable cutting inserts are most often employed with negative cutting geometries.
  • feature numeral 1 depicts a prior art indexable cutting insert of standardised (ISO 1832:2017) nomenclature C120408 T02045. Projected views, an isometric view and a cross-sectional view of indexable cutting insert 1 are also shown.
  • the prefix‘C’ denotes a cutting insert with a corner angle 2 of 80°; ⁇ 2’ denotes the size of the indexable cutting insert (12.7 mm diameter inscribed circle or‘IC’); ⁇ 4’, the thickness T (4.76 mm) and ⁇ 8’, the corner radius rs (0.80 mm).
  • Circular corner geometry is most common, however, non-circular geometries are known in the art, as disclosed for example in W02010061849A1 and US6835028B2.
  • the postscript ⁇ 02045’ denotes a chamfered cutting edge 3, the chamfer width (by) ⁇ 20’ representing 20/100 th mm and‘45’ being the angle of the chamfer (y) in degrees.
  • Chamfer angles of 20°, 25°, 30° and 35° are commonly employed with PCBN indexable cutting inserts, though it may be as large as 45°.
  • the chamfer width (by) is most commonly about 0.2 mm for finish machining operations, though it may be variable as in EP1226892B1 , US2006228179A1 and US2006188347A1 , or it may comprise discrete substantially planar facets as in EP1859882B1. For rough machining applications, chamfer width may be as large as 1.0 mm or more.
  • PCBN and ceramic indexable cutting inserts may have a‘chamfered and honed’ edge geometry in which abrasive brushing of the cutting edge 3 results in a slight rounding of 5 - 50 mhi of the extremities of the chamfer land.
  • C-shaped indexable PCBN cutting inserts are the most popular PCBN indexable cutting insert, primarily because the 80° corner angle permits the machining of square shoulders on the component being machined with a single insert.
  • a C-shaped indexable cutting insert such as 1 has four useable edges.
  • the feed and depth of cut are typically in the ranges 0.05 - 0.2 mm and 0.05 - 0.5 mm respectively. Accordingly, the undeformed chip area (or cross- sectional area of cut) is 0.0025 - 0.1 mm 2 and (depending on the corner radius rs) the maximum effective depth of cut, measured normal to the cutting edge, may be about 0.03 mm to 0.1 mm for example.
  • tipped PCBN indexable cutting inserts such as 4 ( Figure 2) are more commonplace.
  • Indexable cutting insert 4 shown also in projected views and isometric view, has four portions or‘tips’ of PCBN fixed to the corners of the insert body 5, usually by brazing processes.
  • Tipped PCBN indexable cutting inserts with one or two useable edges are also commonplace.
  • the volume of expensive PCBN material employed per useable edge is significantly reduced with tipped indexable cutting inserts, but significant additional processing effort and expense is involved, including the cost of cutting the small PCBN tips from larger PCBN discs or plates, pocketing the insert body 5, brazing, ‘top and bottom’ grinding of top face 6 and bottom face 7 in addition to finish grinding processes. Additionally, the presence of a braze joint introduces a risk of braze failure during use.
  • Indexable inserts may sometimes include a clamping hole 8 or they may include a clamping dimple or recess.
  • solid where used in reference to PCBN or any other cutting tool material, will be understood by those skilled in the art to mean an article with uniform composition throughout or alternately expressed, a material lacking internal interfaces other than those associated with the materials microstructure.
  • a distinction will be drawn between‘solid’ PCBN on one hand and‘backed’ PCBN; the latter including a discrete layer of cemented carbide supporting a discrete layer of PCBN.
  • Polycrystalline diamond (PCD) discs may be similarly constructed. Both forms of PCBN for example may receive a thin surface coating after being fashioned into an indexable cutting insert, but each will still retain the attribute of being‘solid’ or‘backed’. Both forms of PCBN are employed for high-, medium- and low- content grades.
  • W02009047166A1 discloses a non-standard solid PCBN indexable cutting insert which is disposed within a larger intermediate holding device having the geometry of standard geometry indexable cutting insert. Also disclosed are means of improving clamping security - a particularly challenging issue where indexable cutting insert size is small, but also of concern for conventional size indexable cutting inserts. Clamping security is an important element of robust and repeatable chip-forming processes. Clamping of indexable cutting inserts is typically by means of a top clamp which is tightened by means of a screw; although pin-lock clamping such as in US4204781A is sometimes employed.
  • EP0144859A2, US6609859B1 , US2013051941A1 , US4477212A and US6017172A describe means of improving clamping security where the indexable cutting insert is dimpled and the top clamp extends into the dimple.
  • US2004213639A1 discloses similar arrangements for superhard materials.
  • GB2037629A discloses superhard indexable cutting inserts which have features on the face opposing the cutting face, which seat securely in the pocket of the tool holder.
  • US6379087B1 and W02004058437A1 discloses other configurations of clamping devices.
  • US5836723A discloses clamping arrangements specific to grooving type tools.
  • PCBN materials may contain 25% to about 95% by volume cubic boron nitride (CBN) and a variety of secondary hard phases and binder phases.
  • the secondary hard phases may be TiCN for example.
  • the binder phase may include AIN and aluminium borides or it may be a metal alloy such as a cobalt alloy.
  • PCBN is sintered at ultra-high pressures and temperatures and is formed most economically as flat discs of diameter 50 to 100 mm.
  • the disc may be a laminate construction including a layer of PCBN integrally bonded to a layer of cemented carbide. Alternatively, the disc may be composed entirely of PCBN - so-called solid materials.
  • non-standard insert geometries are found to be optimal.
  • some non-standard indexable cutting inserts have a thickness dimension which is greatest or greater than either the width or length.
  • the insert may be said to be orientated‘tangentially’ (relative to the direction of primary motion) in the tool holder: see for example US2008025803A1 , W09221465A1 and US2010183386A1.
  • CN106735353A discloses indexable cutting inserts in which the upper part of a main cutting edge at one side is protruded relative to the lower main cutting edge. The upper and lower surfaces of the insert may serve as the rake face.
  • EP1749602B1 discloses an insert in which a first top first upper surface serves as a rake face and in a different clamping arrangement, the side surface serves as a rake face.
  • EP2596889A1 discloses an insert with a centre axis and an upper cutting edge portion displaced angularly about the centre axis relative to one of the lower cutting edge portions.
  • JPWO2012043579A1 discloses inserts similar to EP2596889A1 in terms of the angular displacement of cutting edges on upper and lower faces.
  • JPWO2012147836A1 discloses an indexable drilling insert in which distinct cutting edge regions including the rake face, are formed at the upper face and are alternatively employed depending on the position of the insert in the tool body.
  • W02008120186A1 discloses an insert with two opposing end faces and peripheral surface extending therebetween. A primary relief surface formed by the peripheral surface establishes an obtuse internal angle with one end face and establishes an acute internal angle with the other end face. The end faces establish the rake face.
  • W02014034056A1 discloses an insert with irregular hexagonal opposing faces.
  • indexable cutting inserts for machining operations are provided which are polygonal in nature and which have two opposing parallel main faces defining a thickness dimension and a multiple of inclined faces extending between said main faces.
  • An axis extends normally through said main faces, concentric with an‘inscribed circle’ dimension.
  • Indexable cutting inserts of the present disclosure are operable in machining operations having a feed direction and are characterised in one aspect by the angle subtended between the feed direction and said axis. Said subtended angle may be less than about 30°.
  • Certain embodiments have irregular polygonal main faces and such embodiments may be used for both left-hand and right-hand machining applications.
  • Other embodiments have regular polygonal main faces wherein one main face is rotationally displaced about said axis relative to the other main face. These embodiments may be configured for left-hand machining applications or right-hand machining applications.
  • Embodiments may have six, eight, ten or fourteen useable cutting edges, yet require significantly less hard cutting material in their construction relative to prior art designs.
  • Indexable cutting inserts in accordance with the present disclosure are further characterised by the ratio of the thickness to the inscribed circle diameter: The thickness may be no less than about one third of the inscribed circle and the thickness may be as large as the inscribed circle dimension.
  • Indexable cutting inserts so characterised are inherently strong and resistant to bending stresses and machining vibration which may otherwise be promoted by excessively long moment arms, as may be the case with prior art indexable cutting inserts.
  • Indexable cutting inserts in accordance with the present disclosure advantageously provide for similar machining geometry as conventional indexable cutting tools Embodiments of the present disclosure are convenient to manufacture and facilitate improved utilisation of hard cutting materials.
  • Related method provides for tessellations of blanks for indexable cutting insert production, whereby tessellations are characterised by a high percentage of shared blank edges.
  • Indexable cutting inserts in accordance with the present disclosure may be manufactured from polycrystalline cubic boron nitride, polycrystalline diamond, ceramics such as alumina, sialon or alumina/TiCN composites and even cemented carbides and cermets. They may be employed in turning including square shoulder turning operations, facing, boring, broaching, milling, drilling or any other chip-forming process employing a geometrically defined cutting tool.
  • Figure 1 depicts several views of a prior art indexable cutting insert.
  • Figure 2 depicts several views of a prior art indexable cutting insert.
  • Figure 3 depicts several views of an indexable cutting insert in accordance with the present disclosure.
  • Figures 4A, 4B and 4C depict several views of an indexable cutting insert in accordance with the present disclosure, highlighting cutting geometry parameters.
  • Figure 5 depicts certain aspects of cutting geometry for indexable cutting inserts in accordance with the present disclosure and indexable cutting inserts not in accordance with the present disclosure.
  • Figure 6A and 6B depict two views each of indexable cutting inserts in accordance with the present disclosure; one for right-hand cutting configurations and one for left-hand.
  • Figure 6C is a indexable cutting insert in a right-hand configuration.
  • Figures 7A depicts several views of a tessellation of blank bodies for the indexable cutting insert blank in Figure 7B, both in accordance with the present disclosure.
  • Figure 8A depicts the size of prior art indexable cutting inserts relative to indexable cutting inserts in accordance with the present disclosure and Figure 8B provides a comparison of the number of useable cutting edges per hard cutting material disc for both.
  • Figures 9A and 9B depict several views of an indexable cutting insert in accordance with the present disclosure positioned in tool holders in accordance with the present disclosure.
  • Figures 10 and 1 1 depicts several views of an indexable cutting insert in accordance with the present disclosure positioned in tool holders in accordance with the present disclosure; certain views shown part-sectioned.
  • Figure 12 depicts several indexable cutting inserts in accordance with the present disclosure which have various corner geometries.
  • Figure 13 depicts indexable cutting inserts in accordance with the present disclosure, each have a polygonal aspect and each characterised by an upper main face rotationally displaced relative to a lower main face by an angular quantity.
  • Figure 14A depicts an indexable cutting insert in accordance with the present disclosure and in Figure 14B, a tessellation of blanks for same indexable cutting insert, as may be arranged for wire electro-discharge cutting or laser cutting of insert blanks from larger hard cutting material discs.
  • Figure 15A and 15B depict part-tessellations for square and pentagonal blanks for indexable cutting inserts in accordance with the present disclosure.
  • Figure 16 depicts a blank geometry and indexable cutting inserts derived therefrom.
  • Figure 17A illustrates a blank geometry suitable for manufacturing embodiments of the present disclosure.
  • Figure 17B illustrates a tessellation of the blank geometry in 17A.
  • Figure 17C illustrates an embodiment of the present disclosure derived from the geometry in 17A.
  • Figure 18 depicts indexable cutting insert in accordance with the present disclosure.
  • Figure 19A and 19B depict blank geometries for indexable cutting inserts in accordance with the present disclosure, including coordinate reference frames.
  • Figure 20A, 20B and 20C depict indexable cutting inserts in accordance with the present disclosure, each including symmetry axis.
  • Figure 21 illustrates a means of securing indexable cutting inserts in accordance with the present disclosure.
  • Figure 22 illustrates a means of securing indexable cutting inserts in accordance with the present disclosure. Detailed Description of the Invention
  • the indexable cutting insert 9 shown in side view and related projected views, isometric view and in cross-section, includes two opposing substantially parallel main faces 10 and 1 1 which may be substantially the same size and irregular hexagonal shape and which are separated by a dimension T which denotes the indexable cutting insert thickness.
  • the irregular hexagonal shape of main faces 10 and 11 may be characterised by an apex angle b, where the angle b of each apex on each main face is substantially the same; for example, 60° +/- 3° so as to allow for manufacturing tolerances.
  • Indexable cutting insert 9 includes six inclined faces 12 of substantially the same size and shape.
  • Three of the six inclined faces 12 may subtend an angle a with one of the opposing main faces 10 or 1 1 , while the other three of the six inclined faces 12 may subtend an angle a with the other of the opposing main faces 11 or 10. That is to say, where one inclined face 12 subtends an angle a with a first of two opposing substantially parallel main faces 10, that inclined face 12 is adjacent two other inclined faces 12, each of the two other adjacent inclined faces 12 subtends an angle a with a second main face 11.
  • Each of the inclined faces 12 is adjacent two other inclined faces 12 and may extend towards a first of the main faces 10 (or 1 1 ) to establish a corner geometry 13 with that main face 10 (or 1 1 ).
  • Each of the inclined faces 12 also extends towards a second of the main faces 1 1 (or 10) to establish a main face edge 15, which may in some embodiments, be a sharp edge.
  • Corner geometry 13 may in some embodiments be, for example, a circular corner geometry characterised by a radius rs. The radius rs may be constant along the length of 13 or it may be variable.
  • Other embodiments may have for example, a combination of bevels and or radii, including for example, geometry known in the field as wiper geometry which provides for improved surface finish.
  • the corner geometry may be characterised by a dimension d, d measured in the direction of the main face axis 21.
  • d rs.
  • the intersection of the corner geometry 13 with each of adjacent inclined faces 12 forms corner edges 14.
  • Each of the inclined faces 12 extends towards each of the two adjacent inclined faces 12 to establish inclined face edges 16, which in some embodiments, may be sharp edges.
  • Inclined face edge 16 adjoins the corner edge 14 and the main face edge 15 adjoins the comer edge 14.
  • Inclined faces 12 may extend between either main face edges 15 or between a main face edge 15 and corner geometry 13.
  • Indexable cutting insert 9 may be positioned in a chip-forming operation which is characterised by three substantially orthogonal directions corresponding to the direction of primary motion (vc), the feed direction (f) and the depth of cut direction (ap).
  • the plane defined by directions f and ap will be termed the‘working plane’.
  • indexable cutting insert 9 is orientated relative to the axes denoted vc, f and ap such that the inclined face 12 highlighted in bold serves as the rake face 17 of the tool.
  • main face axis 21 subtends an angle f with the feed direction f, whereby f is less than about 30°.
  • indexable cutting inserts in accordance with the present disclosure will be operable with an angle f less than about 20°.
  • the orientation of indexable cutting insert 9 also ensures sufficient clearance on the flank surfaces of the tool.
  • the flank surfaces of the tool include one inclined face 12 which forms the minor cutting edge flank 18, one main face 10 which forms the major cutting edge flank 19 and the corner geometry 13 which forms the corner edge flank 20.
  • Rake face 17 is presented to the workpiece and includes a major cutting edge 22 established by a main face edge 15, a minor cutting edge 23 established by an inclined face edge 16 and a corner cutting edge 24 established by corner edge 14.
  • the indexable cutting insert geometry and its orientation relative to the directions f, ap and vc is such that the included angle between 22 and 23 when viewed normal to the working plane is 80°; as for ISO-standard C-shape indexable cutting inserts (such as 1 ), and as such, it is suitable for square shoulder machining.
  • each of the features 10, 12, 13, 14, 15 and 16 are intrinsic to the indexable cutting insert 9 whereas in a suitably orientated indexable cutting insert 9 in a chip-forming process, one each of these features establish features 19, 18, 20, 24, 22 and 23 respectively.
  • An indexable cutting insert 9 secured in one position in a chip-forming process may have a particular inclined face 12 establish a rake face 17, while after indexing, the same inclined face 12 may establish a minor cutting edge flank 18.
  • the corner geometry extends parallel to main face edge 15.
  • diametrically opposing inclined faces 12 are those on opposing sides of the inscribed circle (IC), in many embodiments, diametrically opposing inclined faces 12 may be parallel.
  • Indexable cutting insert 9 may have three-fold symmetry about a central axis 21 extending normal to main faces 10 and 1 1. Also, the main face 10 may be essentially identical to main face 11 (an additional two-fold symmetry) and as a result, indexable cutting insert 9 may assume any one of six positions in a suitably configured tool holder. In each of these six positions, it will present equivalent geometry to the workpiece to be machined and therefore, indexable cutting insert 9 has at least six useable cutting edges. Yet a further additional two-fold symmetry will be described below which results in twelve usable cutting edges.
  • a measuring plane 25 (shown hatched) is constructed for the purposes of analysis within indexable cutting insert 9. Measuring plane 25 is parallel to the direction of primary motion vc and in the working plane (defined by the directions ap and f), measuring plane 25 is normal to the corner cutting edge 24 where it intersects the corner cutting edge.
  • the corner geometry is a substantially circular profile of radius rs, but it may alternatively include several discrete bevels and or may be defined by more than one radii.
  • the corner geometry may be characterised in the working plane by two or more radii of varying size.
  • measuring plane 25 Within measuring plane 25 are subtended three related angular quantities which strongly influence cutting performance; the clearance angle 26 (Q1 ), the rake angle 27 (Q3) and the wedge angle 28 (Q2) - all depicted in Figure 4C, in which measuring plane 25 is in the plane of the page. Note, the working plane in Figure 4C is viewed as a line and is denoted by feature numeral 29.
  • the major cutting edge 22 and the minor cutting edge 23 of indexable cutting inserts 9 cutting geometry may be adequately characterised.
  • similar measuring planes 25 on conventional indexable cutting inserts such as 1 the cutting geometry may be compared to indexable cutting inserts in accordance with the present disclosure such as 9.
  • indexable cutting inserts 1 and 9 are orientated with respect to axes f, ap and vc to have substantially the same Q1 values.
  • the values of Q3 are given by 90° + Q3 - Q1 and for the Hx indexable cutting insert in this example, ranges from 102° - 113°.
  • indexable cutting inserts in accordance with the present disclosure may provide for cutting geometries very similar to those existing on conventional indexable cutting inserts, but with greatly improved utilisation of hard cutting materials, avoidance of braze joints and as will be described below, efficient indexable cutting insert manufacturing processes.
  • indexable cutting inserts in accordance with the present disclosure may have Q3 values between about 0° and 45°. More preferably for indexable cutting inserts made from hard cutting materials such as PCBN, PCD and ceramic, Q3 values may preferably be between about 10° and 35°. Preferably for indexable cutting inserts made from hard cutting materials such as PCD, Q3 values may preferably be between about 0° and 30°; or it may even be negative. (Note, a negative value for Q3 equates to a positive rake configuration and vice-versa). As such tools are suitable for machining relatively soft or moderately hard materials such as aluminium alloys, cast irons and titanium alloys.
  • indexable cutting insert 9 will reveal that there may be twelve corner edges 14. In a right-hand tool configuration, six of these corner edges 14 may be a corner cutting edge 24. In a left-hand tool configuration, six other of these corner edges 14 may be a corner cutting edge 24. The handedness of a machining process may be understood as the feed direction relative to the direction of primary motion.
  • indexable cutting insert 9 is positioned in a left-hand configuration 30 so as to present rake face 17 to the workpiece to be machined (not shown). Indexable cutting insert 9 in 30 will feed leftwards across the page.
  • indexable cutting insert 9 is positioned in a right-hand configuration 31 so as to present rake face 17 to the workpiece to be machined (not shown). Indexable cutting insert 9 in 31 will feed rightwards across the page. The six usable edges on indexable cutting insert 9 in configuration 31 are different to the six useable edges on indexable cutting insert 9 in configuration 30.
  • indexable cutting insert 9 is positioned in a right-hand configuration 32 so as to present rake face 17 to the workpiece to be machined (not shown). Indexable cutting insert 9 in 32 will feed rightwards across the page. Note, 32 differs from 30 solely by an anti-clockwise rotation of 90° on the page. Configuration 32 and 31 are both right-handed configurations, but require different tool holders as described below.
  • indexable cutting insert 9 may be fashioned economically from discs of hard cutting materials such as PCBN.
  • Figure 7A shows a tessellation 33 of ‘blanks’ 34 for indexable cutting inserts 9 positioned within a circle 35 which may represent the outer diameter of a hard cutting material disc.
  • tessellation 33 may be formed within a hard cutting material plate.
  • the planar surfaces of the hard cutting material disc or plate may be normal to axis 21 of blanks 34.
  • Tessellation 33 is efficiently wire- electro discharge cut or laser cut as the majority of adjacent inclined faces 12 are formed during a single pass of the wire or the laser.
  • an indexable cutting insert such as 9 provides suitable geometry for machining hard materials and can be efficiently extracted from hard cutting material discs.
  • Blanks 34 may be additionally processed by EDM, laser-forming or ablation, grinding, lapping or honing or a combination of same; including for example, so as to produce corner geometries 13.
  • Blanks 34 may alternatively be formed by sintering processes known to those skilled in the art of ceramic, cermet and cemented carbide production. It will be clear that inclined faces 12 on blanks 34 may be only partly modified in the shaping of blanks 34 to produce indexable cutting inserts 9.
  • an indexable cutting insert 9 may have minor cutting edge flank 18 and rake face 17 which are substantially conformal with inclined faces 12 from which the insert 9 was produced.
  • Indexable cutting insert embodiment 9 and has been defined by at least two main faces 10 and 11 and six inclined faces.
  • Embodiments of the present disclosure include blanks 34 whose geometry may be defined also by the main faces 10 and 1 1 , the parameters T (thickness) and the angle of incline a of inclined faces.
  • Blanks 34 of the present disclosure include main face edges 15 and main faces 10 and 1 1 , and those skilled in the art will appreciate that features of blanks 34 including main face edges 15 and main faces 10 and 1 1 may also be features of indexable cutting inserts, irrespective of any processing steps to convert the former to the latter.
  • Each main face 10 and 1 1 of blanks 34 in Figure 7 A is an irregular hexagon, with six main face edges 15, each edge 15 subtending an angle b with adjacent edges.
  • Embodiments of blanks 34 of the present disclosure characterised by irregular hexagons may have main face edges 15 on main face 10 parallel to corresponding main face edges 15 on main face 1 1.
  • Each apex on main face 10 has a corresponding apex on main face 1 1.
  • corresponding main face edges 15 represent directrices 36 ( Figure 7B)
  • the inclined face edge 16 extending between corresponding apices can be considered a generatrix 37.
  • Programming WEDM and or laser machines may be based on first constructing main face edges as directrices 36 and determining the path of the wire or laser which effectively serves as the generatrix 37.
  • the programmed directrix for WEDM or laser may be between and equidistant to adjacent directrices 36 on adjacent blanks 34.
  • Embodiments of finished indexable cutting inserts of the present disclosure, such as 9, may be produced from blanks such as 34. Conversion of blanks such as 34 to indexable cutting inserts such as 9 may include grinding, honing or lapping, or EDM or laser forming of corner geometry 13. Some embodiments also may include such processing steps applied to inclined faces 12 and main faces 10 and 1 1. Where a main face edge 15 is partially or entirely replaced with a corner geometry 13, it will be understood that reference to a main face edge 15 will remain geometrically meaningful and similarly so for inclined face edges 16.
  • the majority area of inclined faces 12 and main faces 10 and 1 1 on indexable cutting inserts 9 of the present disclosure may be substantially conformal with inclined faces 12 and main faces 10 and 1 1 of blanks 34 used in their manufacture.
  • the parameters T and a will be non-zero and hence, corresponding main face edges will differ in length. It is a feature of the present disclosure that the rate of progression of the wire or laser beam along individual corresponding directrices 36 need not be proportional to the length of those individual corresponding directrices.
  • the rate of progression of the wire or laser beam along individual corresponding directrices 36 may be substantially equal over a finite portion of the corresponding directrices.
  • the rate of progression of the wire or laser beam along individual corresponding directrices 36 may be substantially equal over regions of the corresponding directrices near corresponding apices of main faces 10 and 1 1.
  • FIG. 8A depicts prior art indexable cutting insert blanks for W1204, W0903, C1204, C0903, S1204 and S0903. Also shown are indexable cutting insert blanks 34 in accordance with the present disclosure, denoted‘Fix’.
  • the value in brackets is the value of the inscribed circle (1C) parameter in mm and the postscripts ⁇ 3’ and ⁇ 4’ denote thickness (T) values of 3.18 and 4.76 mm respectively.
  • indexable cutting inserts in Figure 8A are shown at the same scale and note the scale bar of 10 mm.
  • Such insert blanks - those of the prior art and those in accordance with the present disclosure - may be cut from larger discs or plates of hard cutting materials, or they may be sintered as stand-alone blanks. The former is more common for superhard materials including PCBN and polycrystalline diamond (PCD) and both these materials may particularly benefit from the present disclosure.
  • Figure 8B illustrates the number of useable edges on indexable cutting inserts of the prior art and those in accordance with the present disclosure, as a function of the hard cutting material disc size. As noted above, presently available hard cutting material disc sizes range from about 50 mm to about 100 mm.
  • indexable cutting inserts in accordance with the present disclosure are where six of the potentially twelve useable cutting edges are utilised: where all twelve edges are utilised, indexable cutting inserts such as 9 have twice the utilisation of cutting tool material as prior art inserts. Even where only six of the twelve usable edges are utilised, indexable cutting inserts such as 9 remain beneficial. Relative to W09 indexable cutting inserts, most inserts of the present disclosure have shared inclined faces 12 during cutting, whereas W-shape inserts have a small minority of shared sides. S-shaped inserts are incapable of square shoulder machining operations.
  • indexable cutting inserts of the present disclosure are inherently stronger, not least as their more equiaxed form limits bending stresses which can otherwise lead to insert breakage, in both continuous and interrupted machining applications - prior art inserts are more plate-like and larger bending stresses can develop due to the inherently longer moment arms.
  • the plate-like form of prior art cutting inserts employed presently with PCBN is an inheritance from the earlier development of (primarily) cemented carbide inserts, where longer edge lengths were warranted. Despite the fact that many applications for PCBN and ceramic cutting inserts are finishing operations or even semi-finishing operations, plate-like geometry indexable inserts have persisted despite the absence of industrial need for long edge lengths.
  • Figure 9A depicts a tool holder 38 for use with indexable cutting inserts such as 9.
  • the clamp 39 is pre-loaded by clamp spring 40 so as to provide ease of removal and insertion of insert 9.
  • an ejector seat element 41 to further facilitate ease of removal and insertion of insert 9.
  • Indexable cutting insert 9 seats in pocket 42 which is geometrically configured to provide secure seating in cooperation with clamp 39.
  • Pocket 42 may be formed by the forward aspect of ejector seat element 41.
  • tool holder 43 Figure 9B
  • Both 43 and 38 are suitable for right-hand machining operations.
  • a tool holder for left hand machining operations may be similarly constructed; those skilled in the art will appreciate that such may be visualised by simply mirroring tool holders 43 and 38.
  • Those skilled in the art will also appreciate the manner in which milling cutters and even drilling tools may be constructed following the description of embodiment 38.
  • Reference to machining process within this disclosure will include turning, facing, boring, broaching, milling, drilling or any other chip-forming process employing a geometrically defined cutting tool.
  • Figures 10 and 1 1 depict tool holder 38 in part-sectioned view, so as to illustrate construction of ejector seat element 41.
  • the ejector seat element 41 may be operated by means of a cam 44 which may be turned for example by the socket head 45.
  • the ejector seat element 41 may alternatively be operated by means of an ejector spring 46 ( Figure 1 1 ). Indexable cutting insert 9 in Figure 1 1 is shown in an ejected position with clamp 39 retracted by clamp spring 40.
  • Ejector seat element 41 may be alternatively operated by a pneumatic or hydraulic cylinder and piston, or it may be manually operated directly by means of a knob located externally to tool holder 38 or 43 or similar tool holders.
  • Clamping may be additionally or alternatively facilitated by a pin-lock device as are known in the art, whereby for example, a clamping screw extends through a bore normal to main faces 10 and 11 and coincidently with axis 21 into a threaded bore in the tool holder body; threaded bore also substantially coincident with axis 21.
  • a pin-lock device as are known in the art, whereby for example, a clamping screw extends through a bore normal to main faces 10 and 11 and coincidently with axis 21 into a threaded bore in the tool holder body; threaded bore also substantially coincident with axis 21.
  • Embodiments of the present disclosure may range in size and geometry.
  • the thickness T may be 2.0 mm or less, or more preferably it may be between 2.5 and 8 mm; the latter for operations characterised by high stock removal rates for example. Most preferably for finish machining operations, it may be between 3.16 and about 6.35 mm.
  • the inscribed circle (IC) dimension may be between about 4.0 mm or it may be as large as about 25 mm. Small IC indexable cutting inserts may for example, be utilised in boring operations or for low stock removal outside diameter turning or milling operations. More preferably for finish machining operations, the IC may be between 4.0 mm and 12.7 mm.
  • dimension T will be no less than about one third the IC dimension.
  • dimension T will be no less than about one half the IC dimension and will be not substantially larger than the IC dimension.
  • the ratio of T:IC may influence the structural rigidity of indexable cutting inserts in accordance with the present disclosure, their seating security, the utilisation of hard cutting materials and ability to grind features such as 13.
  • the value a may be less than 90°, for example, it may be less than or equal to 85° or even less than 80°. In embodiments for which data is provided in Figure 5, a is 75° for example. More generally, a may be as small as about 60°. For example, where the effective corner angle 2 - as determined by projection of major cutting edge 22 and minor cutting edge 23 onto the working plane - need not be as large as 80°, a may be significantly less than 80°. Noting the inclination of the rake face 17 to be dependent on the value of a, where a is less than about 60°, excessively negative cutting geometry may result for some machining applications.
  • the cutting geometry may be excessively negative.
  • the majority of finish-machining applications for hardened work materials may have a in the range 75° - 85°.
  • Corner geometries 13, which establish the corner cutting edge 24 in application may be circular in nature or may comprise more than one circular form and or more than one bevel or facet form.
  • embodiments of indexable hexagonal cutting inserts in accordance with the present disclosure may have a circular form 47 for corner geometry 13, whereby the radius rs may be between about 0.2 mm and about 2.4 mm.
  • comer geometries such as 48 and 50 may comprise a bevel 49 and two different size radii which are substantially tangent to the minor cutting edge flank 18 and the major cutting edge flank 19 respectively.
  • Corner geometry 13 may comprise three bevels for example as in embodiment 51 and 52.
  • embodiments of the present disclosure, such as 52 may include a cutting edge bevel 53 along the major cutting edge 22 and or the minor cutting edge 23 and or the corner cutting edge 24.
  • Each of these corner geometries 13 may be characterised by the dimension d, as measured in the direction of the main face axis 21
  • Alternative embodiments of indexable cutting inserts of the present disclosure may have main faces 10 and 11 which are regular polygons.
  • embodiments may have regular pentagonal or heptagonal main faces, as with indexable cutting inserts 54 and 55 respectively in Figure 13.
  • Indexable cutting insert 56 has substantially square main faces.
  • main faces 10 and 11 are rotationally offset about central axis 21 by angle K.
  • the number of useable edges is 8, 10 and 14 respectively and the inserts 54, 55 and 56 are by design either entirely left-handed or entirely right-handed.
  • Indexable cutting inserts 54, 55 and 56 are shown lying in a horizontal plane (axis 21 aligned to the long edge of the page) and positioned substantially in the vertical plane orientated relative to axis vc, ap and f as they may be orientated in a machining operation.
  • Embodiment 57 is related to embodiment 54 and has a corner geometry 13 characterised by a variable radius extending partially along main face edges 15. In this embodiment therefore, inclined faces 12 extend between at a first main face 10, one main face edge 15 and one corner geometry 13 and at a second main face 1 1 , one main face edge 15 and one corner geometry 13. Similar features may be provided in embodiments 55 and 56. Furthermore, features depicted in Figure 12 may be included in embodiments 54, 55 and 56.
  • indexable cutting inserts 9, 54, 55, 56 and 57 are within about 30° of normal to the feed direction, i.e., f will be not substantially larger than about 30°. Many embodiments will be operable where the main face 10 and 11 are within about 20° of normal to the feed direction. That is to say, the angle subtended f by the axis 21 extending normal to main faces 10 and 1 1 and the feed direction will be about 30° or 20° or less.
  • Embodiments such as 54, 55 and 56 may be characterised by an inscribed circle 1C substantially concentric with axis 21 and tangent to main face edges 15, the number of edges n on the polygonal main faces 10 and 1 1 , the thickness T and the angle K.
  • Embodiments of the present disclosure so characterised may have n in the range 4 - 7.
  • Thickness T may be in the range 2 mm to about 8 mm or more preferably 3.2 mm to about 6.5 mm.
  • dimension T will be no less than about one third the IC dimension. Most preferably, dimension T will be no less than about one half the IC dimension and will be not substantially larger than the IC dimension.
  • the ratio of T:IC may influence the structural rigidity of indexable cutting inserts in accordance with the present disclosure, their seating security, the utilisation of hard cutting materials and ability to grind features such as 13 and 49.
  • the angle k may be in the approximate range 5° to 30°.
  • the inscribed circle IC dimension may be defined by the diameter of the circle tangent to the intersections of inclined faces 12 with the plane equidistant to and parallel to each of main faces 10 and 11.
  • the inscribed circle IC diameter thereby derived is equivalent to the definition illustrated in Figure 13.
  • Inclined face edges 16 may serve as the minor cutting edge 23 when the indexable cutting inserts such as 54, 55, 56 and 57 are suitable orientated in a machining process.
  • Main face edges 15 may serve as the major cutting edge 22 when the indexable cutting inserts such as 54, 55, 56 and 57 are suitable orientated in a machining process.
  • inclined faces 12 may serve as rake faces 17 or in other‘indexed’ positions in tool holders such as 38 or 43, may serve as the minor cutting edge flank 18.
  • the geometry of inclined faces 12 may be defined by directrices 36 and generatrices 37 as described in relation to embodiment 34 in Figure 7B.
  • Figure 14A depicts an embodiment 58 of the present disclosure where parallel main faces 10 and 11 are regular hexagons; said main faces rotationally displaced relative to each other by an angle k about main face axis 21. Corner geometry 13 continues from main face edge 15 and has a substantially circular profile of varying radius in the direction of 15. Each of main face edges 15 are adjacent corner geometries 13. Inclined faces 12 may form a rake face 17 when indexable cutting insert 58 is suitably orientated in a machining operation.
  • Tessellation 59 ( Figure 14B) includes blanks 34 which may be employed in the manufacture of indexable cutting insert 58.
  • Blanks 34 lie adjacent each other such that one inclined face 12 on one blank 34 will be cut simultaneously with an inclined face 12 on an adjacent blank 34; thereby improving the efficiency of WEDM or laser cutting of hard cutting materials, such as PCBN and PCD.
  • Examination of the detail view of tessellation 59 in Fig 14b reveals that very little hard cutting material is wasted in forming blanks 34.
  • embodiments such as 54, 55, 56, 57 and 58 may be oriented in a machining process so as to provide an effective corner angle less than 90° and hence, may be employed for square-shoulder machining operations or even acute angle shoulder machining operations.
  • Embodiments such as 54, 55, 56, 57 and 58 are also inherently structurally strong and resistant to high cutting forces, not least because no large moment arm is present (or can develop during application) as is the case with prior art indexable cutting inserts.
  • Yet a further benefit of embodiments 54, 55, 56 and 57 and similar forms is that blanks 34 for insert manufacture may be efficiently cut from hard cutting material discs, by WEDM or laser cutting for example.
  • the majority area of inclined faces 12 and main faces 10 and 11 on indexable cutting inserts 9, 54, 55, 56, 57 and 58 of the present disclosure may be substantially conformal with inclined faces 12 and main faces 10 and 11 of blanks 34 used in their manufacture.
  • the inclined faces 12 and main faces 10 and 1 1 on indexable cutting inserts 9, 54, 55, 56, 57 and 58 may be, or may substantially be the inclined faces 12 and main faces 10 and 1 1 of blanks 34 used in their manufacture.
  • the inclined faces 12 and or main faces 10 and 1 1 on indexable cutting inserts 9, 54, 55, 56, 57 and 58 may be formed by grinding, lapping, polishing, honing, EDM-forming or laser-forming (or a combination of such) of inclined faces 12 and or main faces 10 and 11 of blanks 34 used in their manufacture.
  • Laser forming may include laser ablation and EDM-forming may include die-sink or wire EDM or electro-discharge grinding (EDG).
  • 60 is a tessellation of blanks 34 for indexable cutting inserts having substantially square main faces 10 and 11 such as embodiment 56.
  • Main faces 10 and 11 are both parallel in Figure 14A to the plane of the page and may be normal to axis 21 of blanks 34.
  • Several inclined faces 12 in one blank 34 are opposing inclined faces in another blank and hence, are formed by a single cut in WEDM or laser cutting processes.
  • Tessellation 61 ( Figure 15B) includes blanks 34 having regular pentagonal mains faces 10 and 11 (parallel to the plane of the page which may be normal to axis 21 of blanks 34). For such pentagon-style indexable cutting insert blanks 34, optimal tessellations provide for up to about 80% of inclined faces shared.
  • optimal tessellations provide for up to about three fourths of inclined faces shared. Both cases are significantly greater than with W-style prior art indexable inserts while the percentage of hard cutting material disc utilised is about equivalent in all three cases. It will be appreciated that tessellations provided here by way of illustration may be enlarged so as to contain a great number of blanks or a number of blanks which is sufficient to consume a disc or defined area of a disc or plate of hard cutting material.
  • the term‘tessellation’ will relate to the repeating spatial relationships between individual blanks and will not be limited in meaning to a specific number of blanks within the tessellation.
  • All tessellations 33, 59, 60 and 61 of blanks 34 described herein include a gap between neighbouring blanks 34. Those skilled in the art will understand these gaps relate to the ‘kerf width from a laser- or WEDM-cutting process.
  • Note tessellations 33, 59, 60 and 61 of blanks 34 may be reduced to practice using computer aided drawing (CAD) software for example and this may be a basis for generation of computer numeric code (CNC) using computer aided manufacturing (CAM) software for example and such CNC code may be used to control WEDM or laser cutting machines.
  • CAD computer aided drawing
  • CNC computer numeric code
  • CAM computer aided manufacturing
  • a tessellation may therefore be considered as a means to control a cutting process. This and the steps involved will be implied in the phrase‘cutting a tessellation of blanks 34’.
  • Blank geometry 62 may serve as basis for manufacture of indexable cutting insert embodiment 63 which has a negative rake face 17 geometry (note orientation of 63 relative to f-ap-vc coordinate system).
  • Indexable cutting insert 63 may be constructed in PCBN or ceramic for example.
  • Blank geometry 62 mirrored in one of faces 10 or 11 may also serve as basis for manufacture of indexable cutting insert embodiment 64.
  • Embodiment 64 has a substantially neutral rake face 17 geometry in the vicinity of the corner cutting edge 24. In comparing embodiments 63 and 64, note the locations of the corner geometries 13 which form corner cutting edges 24 relative to inclination of rake faces 17.
  • Embodiment 64 also includes a clamping hole 65, which may be alternatively or complimentarily be employed to secure the insert 64 in a tool holder with a top clamp such as 40 in Figures 9 to 1 1. Clamping hole 65 is aligned with axis 21.
  • Embodiment 64 may be manufactured for example in PCD (solid or laminate construction) for machining non- ferrous metals and grey cast iron. It may also be manufacture in PCBN for similar applications or other hard cutting materials.
  • Embodiments such as 63 and 64 each have ten useable cutting edges, all of the same handedness. Those illustrated are for left-handed operations and those skilled in the art will appreciate the ease of rendering same essential forms for right-handed operations. It is emphasised that the angle k may be negative or positive depending on the handedness of the required indexable cutting insert. Any ranges stated for this angle will be understood as absolute values, which in practice may be positive or negative depending on the particular coordinate system employed.
  • Embodiment 66 is a blank employable for the production of indexable cutting inserts in accordance with the present disclosure.
  • Blank 66 includes two main faces 10 and 1 1 , between which extend four inclined face edges 16.
  • Each main face 10 and 1 1 is bounded by four inclined faces 12, each inclined face 12 is adjacent both main face 10 and 1 1.
  • Inclined faces 12 include two primary inclined face facets 67 and two secondary inclined face facets 68.
  • a continuous curved surface may extend between the primary inclined face facets 67 as an alternative to two secondary inclined face facets 68.
  • primary inclined face facets may be non-planar.
  • Embodiment 66 may be characterised by an inscribed circle diameter IC and the angle g, where g represents, in a view parallel to main face axis 21 , the orientation of a first primary inclined face facet relative to a second primary side face facet.
  • Embodiment 69, Figure 17B is a tessellation of indexable cutting insert blanks 66, as may be arranged for the production of blanks 66 from a disc of hard cutting material such as PCBN, PCD or ceramic, using WEDM- or laser- cutting methods.
  • main face edges 15 in embodiment 66 represent the boundary of intersection of each of main faces 10 and 11 with each of four adjacent primary inclined face facets 67 and secondary inclined face facets 68; i.e., where there are n useable cutting edges, there will be n main face edges 15.
  • Main faces edges 15 on the main faces 10 and 11 in embodiments such as 69 are related through the angle of rotation g about the main face axis 21 and a‘point symmetry’. That is to say, where a main face edge 15 on a main face 10 is rotationally displaced by an amount g relative to a substantially opposing main face edge 15 on main face 11
  • Embodiment 70 is an indexable cutting insert in accordance with the present disclosure, as may for example be manufactured from blank 66.
  • Embodiment 70 provides eight identical cutting edges, all suitable for square shoulder machining. It includes main faces 10 and 1 1 , corner geometry 13, primary inclined face facets 67 and secondary inclined face facets 68; two of each of 67 and 68 constituting an inclined face 12.
  • Embodiment 70 is shown orientated relative to substantially orthogonal axes denoted f, ap and vc, which represent the directions of feed, depth of cut and primary motion direction respectively, in a chip forming process.
  • one primary inclined face facet 67 serves as the rake face 17, while an adjacent primary inclined face facet 67 serves as the minor cutting edge flank 18.
  • Main face 10 serves as the major cutting edge flank 19.
  • the inclined face edge 16 adjacent the rake face 17 forms the minor cutting edge 23.
  • Corner geometry 13 establishes corner edge flank 20, which in the embodiment shown in Figure 17C is a radius of uniform dimension 71 along a portion of the main face edge 15.
  • Embodiment 70 suitably orientated for a chip-forming operation, as in Figure 17C, will have a main face axis 21 which subtends an angle f with the feed direction T .
  • Embodiments of the present disclosure will preferably have angle f ⁇ 30 degrees.
  • Embodiments of the present disclosure will preferably have T ⁇ IC.
  • Embodiment 72 in Figure 18 is a further embodiment of the present disclosure. It is similar to embodiment 70 in that it comprises primary inclined face facets 67 and secondary inclined face facet 68, but includes ten useable cutting edges, all capable of square shoulder machining. Corner geometry 13 which forms the corner edge flank 20 includes a radius of varying size 73 disposed along a portion of the main face edge 15. The primary inclined face facet 67 highlighted in bold line serves as the rake face 17, with the adjacent primary inclined face facet 67 serving as the minor cutting edge flank 18.
  • Embodiments 70 and 72 both provide the negative cutting geometry which is particularly suitable for cutting hardened workpiece materials such as hard steel, super alloys, sintered irons and high chrome cast irons and similar ferrous alloys.
  • the dihedral angle between adjacent primary inclined face facets (67) be greater than about 90° and less than about 160°.
  • the Y-axis extends normal to the main face edge 15 which lies in the first main face 10 and borders the inclined face 12 under consideration.
  • the geometry of inclined face 12 is provided by Equations 1 , where the permissible values for X and Z are provided by Equations 2 and 3 respectively.
  • the symbol p represents the ratio of a circles’ perimeter to its diameter.
  • the Y- axis extends normal to the main face edge 15 which lies in the first main face 10 and borders the inclined face 12 under consideration.
  • the inscribed circle diameter‘IC’ is tangent to main face edges 15, or equivalently, tangent to the intersections of each of the inclined faces 12 with a mid-plane parallel to and equidistant to main faces 10 and 11.
  • Equation 4 The geometry of inclined face 12 is provided by Equation 4, where the permissible values for X, Y, Z are provided by Equations 3, 5 and 6.
  • the handedness of the indexable cutting insert will be denoted by the parameter K: for right-handed indexable cutting inserts, k will have a positive value and for left-handed inserts, k will have a negative value.
  • Equations 1 - 3 and Equations 3 - 6 may be substantially applicable also to indexable cutting insert embodiments of the present disclosure, wherein corner geometries 13 and or various edge geometries, as depicted in Figure 12 for example, are provided.
  • Inclined faces 12 will retain the essential characteristics described by Equations 1 - 3 and 3 - 6. That is to say, Equations 1 and 4 may preferably characterise inclined faces 12 for at least 50% of the stated permissible range of values provided in Equations 2 and 3 and Equations 3, 5 and 6, respectively. More preferably, Equations 1 and 4 may characterise inclined faces 12 for at least 60% of the stated permissible range of values provided in Equations 2 and 3 and Equations 3, 5 and 6, respectively.
  • Equations 1 and 4 may characterise inclined faces 12 for at least 70% of the stated permissible range of values provided in Equations 2 and 3 and Equations 3, 5 and 6, respectively.
  • One particular advantage of embodiments of the present disclosure derives from the highly efficient use of hard cutting materials for indexable cutting inserts.
  • the number of useable cutting edges per volume of hard cutting material may be twice that provided by prior art indexable cutting inserts. This both arises from and enables cutting geometries which are particularly suitable for machining, including but not limited to square shoulder machining, hardened work materials - for example, embodiments 9, 58 and 72.
  • Other embodiments such as 64 are provided with cutting geometries suitable for more ductile work materials which favour a positive cutting geometry. It will be appreciated by those experienced in the art that embodiments of the present disclosure need not be restricted to the classes of work material noted above by way of example.
  • Embodiments of the present disclosure have particular symmetries which permit the same inclined face 12 or primary inclined face facet 67 to serve as a rake face 17 in one index position and to serve as a minor cutting edge flank 18 in another index position.
  • This symmetry will be apparent from the intersection of a mid-plane parallel and equidistant to both main faces 10 and 1 1 with inclined face edge 16; the resulting inclined face edge mid- point 74 being illustrated in Figure 20.
  • Each embodiment of the present disclosure will have a centroid 75, the term‘centroid’ meaning the geometrical centre of the indexable cutting insert, which in embodiments having uniform density will mean also the centre of gravity.
  • the symmetry axis 76 extends between the centroid 75 and the inclined face edge mid- point 74.
  • Rotation of indexable cutting inserts of the present disclosure 180 degrees about the symmetry axis 76 will result in substantially identical geometry: Inclined faces 12 or primary inclined face facets 67, adjacent the inclined face edge mid-point 74 and corner geometries 13 adjacent those inclined faces 12 or primary inclined face facets 67, will have substantially identical geometry in space before and after said 180 degree rotation.
  • Embodiments of the present disclosure such as 72 and 70 possess additional symmetry.
  • second symmetry axis point 77 is equidistant to a first and a second inclined face edge mid-point 74.
  • a second symmetry axis 78 extends from centroid 75 through 77.
  • the first and second inclined face edge mid-point 74 are adjacent each other.
  • the primary inclined face facets 67 apposing the first inclined face edge mid-point 74 are symmetrical with the primary inclined face facets 67 apposing the second inclined face edge mid-point 74 through a 180 degree rotation about the second symmetry axis 78.
  • Embodiment 79 in Figure 21 illustrates in exploded isometric projection, an arrangement for clamping embodiment 80 of indexable cutting inserts of the present disclosure.
  • Insert seat plate 81 will be secured by permanent means or semi-permanent means to the tool post front section 83, thereby securing top-clamp 82 in position.
  • Indexable cutting insert 80 seats in seat plate 81 and is secured by means of the top-clamp 82 secured with a socket-head screw for example (not shown).
  • Embodiment 84 in Figure 22 depicts an alternative arrangement for clamping embodiments of the present disclosure such as 85, in which there is a clamping hole 65.
  • the pin-locking arm 86 is secured in the tool post front section 87 by means of Insert seat plate 81 .
  • the pin-locking arm 86 With insert 85 seated in the Insert seat plate 81 and with clamping pin 88 disposed within clamping hole 65, the pin-locking arm 86 is displaced by means of a screw (not shown) bearing against the oblique face 89, thereby, securely retaining the insert 85.
  • indexable cutting inserts and blanks for the manufacture of same may be made in PCBN, PCD, ceramic, cermet and cemented carbide for example.
  • Ceramic tool materials include for example alumina, composites including alumina and TiC or TiCN, sialons, silicon nitride and whisker reinforced alumina.
  • Some embodiments may be constructed for example, from hard cutting material discs of laminate construction - such as those including a layer of PCD or PCBN integrally bonded to a support layer of cemented carbide.
  • indexable cutting inserts in accordance with the present disclosure may be coated using for example PVD and or CVD processes wherein the coating may be between about 0.5 mpi and about 20 mpi in thickness (as measured normal to the coated surface) and may contain for example, oxides, nitrides, carbides, or combinations thereof, of metals including one or more of Ti, Al, Cr, Si, V.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
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Abstract

L'invention porte sur des plaquettes de coupe indexables (70, 72) qui sont particulièrement, mais pas exclusivement, appropriées pour des opérations de formation de puce sur des matériaux de travail durs. Les plaquettes de coupe indexables (70, 72) de la présente invention sont utilisées selon une orientation sensiblement tangentielle, ce par quoi, en raison de symétries spécifiques, les faces latérales inclinées pouvant fonctionner en tant que face de coupe dans une position d'index peuvent fonctionner en tant que faces de flanc de bord de coupe secondaire dans une autre position d'index. Des modes de réalisation concernent huit à seize bords de coupe utilisables, comprenant des géométries de coupe appropriées pour des opérations d'usinage d'épaulements carrés. Un avantage des modes de réalisation des plaquettes de coupe indexables selon l'invention comprend une utilisation plus efficace de matériaux de coupe durs tels que le nitrure de bore cubique polycristallin, la céramique et le diamant polycristallin. Des procédés de fabrication de plaquettes de coupe indexables plus efficaces sont possibles.
PCT/EP2019/025058 2018-03-01 2019-03-01 Plaquette de coupe indexable WO2019166133A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB1803381.1A GB201803381D0 (en) 2018-03-01 2018-03-01 Indexable cutting insert and method of manufacture
GB1803381.1 2018-03-01

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WO2019166133A1 true WO2019166133A1 (fr) 2019-09-06

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012104832A1 (fr) * 2011-01-31 2012-08-09 Iscar Ltd. Insert de coupe tangentiel et fraise
WO2014034056A1 (fr) * 2012-09-03 2014-03-06 日本特殊陶業株式会社 Inserts de coupe et outils de coupe utilisant ceux-ci
WO2015137509A1 (fr) * 2014-03-14 2015-09-17 株式会社タンガロイ Plaquette de coupe, corps d'outil et outil de coupe
EP2946858A1 (fr) * 2014-05-19 2015-11-25 Sandvik Intellectual Property AB Insert d'outil de coupe porte-outil de coupe

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012104832A1 (fr) * 2011-01-31 2012-08-09 Iscar Ltd. Insert de coupe tangentiel et fraise
WO2014034056A1 (fr) * 2012-09-03 2014-03-06 日本特殊陶業株式会社 Inserts de coupe et outils de coupe utilisant ceux-ci
WO2015137509A1 (fr) * 2014-03-14 2015-09-17 株式会社タンガロイ Plaquette de coupe, corps d'outil et outil de coupe
EP2946858A1 (fr) * 2014-05-19 2015-11-25 Sandvik Intellectual Property AB Insert d'outil de coupe porte-outil de coupe

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