GB2436723A - Drill bit with polycrystalline diamond inserts - Google Patents

Drill bit with polycrystalline diamond inserts Download PDF

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Publication number
GB2436723A
GB2436723A GB0706061A GB0706061A GB2436723A GB 2436723 A GB2436723 A GB 2436723A GB 0706061 A GB0706061 A GB 0706061A GB 0706061 A GB0706061 A GB 0706061A GB 2436723 A GB2436723 A GB 2436723A
Authority
GB
United Kingdom
Prior art keywords
drill bit
carbide
cutting edge
pcd
diameter
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.)
Withdrawn
Application number
GB0706061A
Other versions
GB0706061D0 (en
Inventor
Paul Anthony Graham
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.)
Technicut Ltd
Original Assignee
Technicut 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 Technicut Ltd filed Critical Technicut Ltd
Publication of GB0706061D0 publication Critical patent/GB0706061D0/en
Publication of GB2436723A publication Critical patent/GB2436723A/en
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B51/00Tools for drilling machines
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2226/00Materials of tools or workpieces not comprising a metal
    • B23B2226/27Composites
    • B23B2226/275Carbon fibre reinforced carbon composites
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2226/00Materials of tools or workpieces not comprising a metal
    • B23B2226/31Diamond
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2240/00Details of connections of tools or workpieces
    • B23B2240/08Brazed connections
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2251/00Details of tools for drilling machines
    • B23B2251/14Configuration of the cutting part, i.e. the main cutting edges
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23BTURNING; BORING
    • B23B2251/00Details of tools for drilling machines
    • B23B2251/50Drilling tools comprising cutting inserts

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Processing Of Stones Or Stones Resemblance Materials (AREA)
  • Drilling Tools (AREA)

Abstract

A drill bit 11 for drilling holes in composite materials such as carbon fibre reinforced composites (CFCs) and glass fibre reinforced composites (GRPs), has a solid carbide body 14 and possesses dagger geometry, with 180{ opposed flats converging towards an apex 8 of the bit to define two cutting edges 19, 20. A lower rotational speed inner zone 15 of each cutting edge comprises exposed carbide, and a higher rotational speed outer zone 16 of each cutting edge is defined by portions of two polycrystalline diamond (PCD) inserts 12 spaced 180{ apart and brazed into a receiving seat 13 of the carbide of the body. Preferably the drill bit has a point angle of 30{.

Description

<p>Title of the Invention</p>
<p>Drill Bit</p>
<p>Field of the Invention</p>
<p>This invention relates to a drill bit particularly, but not exclusively for the machining of composite materials, such as carbon fibre reinforced composites (CFC) or glass fibre reinforced composites (GRP) as used in aircraft components such as panels, details, structures and flying surfaces.</p>
<p>Background to the Invention</p>
<p>Aircraft designers are increasingly making use of CFC and GRP in aircraft to construction. There are numerous advantages to be gained from the introduction of composite materials into aircraft construction: - (I) up to 40% weight reduction over the equivalent metallic component; (ii) maintenance costs are reduced over the equivalent metallic component; (ii) radar cross-section is reduced; and is (iv) increased flexibility of component design.</p>
<p>These performance benefits mean that the use of composite technology is being implemented on all new military and commercial programs. It is also being considered to upgrade existing airframe designs to introduce.composite technology to gain a performance advantage.</p>
<p>Industry trends are such that it is projected that around 35% of the Joint Strike Fighter Aircraft will be produced in CFC's and around 22% of the new Airbus A380 aircraft will be CFC's.</p>
<p>The biggest current disadvantage with the introduction of composites is the high costs associated with processing the components once they are in the cured state. A major activity associated with the processing of cured components is the production of drilled holes. The design demands of a drilled hole in a composite component would be that:- (i) there is no visual evidence of exit face de-laminations around the hole; (ii) there is no visual evidence of entry face de-laminations around the hole; (iii) there is no evidence of the structural integrity of the component being damaged around the hole; (iv) there is no evidence of splintering of the composite around the hole; (v) there is no evidence of de-laminations within the hole; and (vi) surface finish within the hole is clean and un-torn.</p>
<p>Once the above criteria can be satisfied to the demands of the drawing and the design specification, the productivity measure can only be expressed in cost per hole.</p>
<p>The factors that determine the cost per hole are detailed:- (i) drill bit life before quality criteria is not achieved, and (ii) cost of drill bit.</p>
<p>As can be seen from the detailing of factors that effect the cost per hole the primary objective is to create a drill bit geometry that achieves the required component quality, after that, the cost of the drill bit and the number of holes that are produced to the quality requirement will determine and govern the cost per hole.</p>
<p>With conventional drill bit geometry and drill bit materials it is possible to achieve the required quality specifications within composite materials, however because of the abrasive nature of composite materials, there are two main problems that occur:- (i) the achievement of the quality demands requires the quality of the cutting edge to be retained, and (ii) once cutting edges exhibit wear the quality demands will fail. As wear appears on the drill bit, increased cutting forces are required. The inefficiency of the worn drill bit requiring increased force will cause quality failures.</p>
<p>Traditional cutting drill bits for hole production in composites could cost in the region of 50.00 each and only produce 10 holes that met the quality criteria, giving a cost per hole of 5.00 per hole.</p>
<p>Object of the Invention A basic objective of the present invention is the provision of an improved drill bit having geometry that can sustain the quality demands of composite components over an extended number of holes, thus reducing the cost per hole.</p>
<p>Summary of Invention</p>
<p>According to the present invention there is provided a drill bit for the drilling of holes in composite materials such as CFC's and GRP's, wherein the drill bit is of solid carbide and of dagger geometry, with 180 opposed flats converging towards an apex of the bit to define two cutting edges, with a lower rotational speed inner zone of each cutting edge of exposed carbide, and with a higher rotational speed outer zone of each cutting edge defined by portions of two polycrystalline diamond (PCD) inserts spaced 180 apart and brazed into respective receiving seats of the carbide of the body.</p>
<p>Advantages of the Invention The drill bit in accordance with the invention thus ensures holes produced are free from any of the current known quality defects.</p>
<p>Thus, the drill bit in accordance with the invention addresses the shortcomings of the existing conventional drill bits by providing extended cutting life and consequently facilitates reduced cost per hole. Compared to current conventional ho'e production methods the cost per hole can be reduced as low as Ò.40p per hole.</p>
<p>Further advantages of the PCD tipped solid carbide dagger drill bit in accordance with the invention compared to a conventional drill bit are that:-s (I) cutting forces are reduced such that no exit face de-laminations are seen; (ii) cutting forces are reduced such that no entry face de-laminations are seen; (iii) cutting forces are re-directed, such that axial forces are converted to radial forces from the design of the drill bit geometry (see below). The result is the removal of damage to the structural integrity of the composite being drilled, due to reduced axial forces; (iv) PCD has the hardness and wear resistance characteristics to maintain a sharp cutting edge for extended periods of machining, thus ensuring the quality of the holes produced is maintained over the prolonged life of the drill bit; and (v) PCD is only applied over part of the cutting edge to provide maximum impact with limited restriction (see below). Drill bit design is such that peripheral surface speeds increase as the diameter of a drill bit increases. The higher the peripheral speed, higher heat temperatures are generated and at higher temperatures greater wear is seen on any cutting tool. The addition of the PCD insert at the location specified in a dagger geometry solid carbide drill bit in accordance with the invention, provides increased wear resistance where it is required.</p>
<p>Similarly, the same properties that make the PCD resistant to wear also make it susceptible to failure in the mode of chipping caused by impact damage or shock loads.</p>
<p>The centre of a drill bit, where the peripheral speed is small, minimal, or zero at the very point of the drill, is subjected to impact or shock loads during the drilling process. * 5</p>
<p>However, the drill bit construction in accordance with the invention, is such that the centre of the drill bit subjected to irn pacts or shock loads is solid tungsten carbide.</p>
<p>Preferred or Optional Features of the Invention The drill bit has a 30 point angle.</p>
<p>Whilst the ratio of PCD to solid carbide basically needs to suit the drill bit diameter as well as the nature of the material to be drilled, some 20% to 70% of the drill bit diameter is in the PCD zone, and some 80% to 30% of the drill diameter is of exposed carbide.</p>
<p>The diameter of the drill bit is in the range of 2mm to 50mm.</p>
<p>The overall length of the drill bit is in the range of 20mm to 330mm.</p>
<p>Each PCD insert has an arcuate seating face, to seat on a correspondingly arcuate receiving face of a recessed, receiving seat in the carbide.</p>
<p>Each PCD insert has a major cutting edge extending towards the apex of the drill bit, and a minor cutting edge at the outer diameter of the drill bit.</p>
<p>is Brief Description of the Drawings</p>
<p>Figure 1 illustrates the geometry of a conventional fluted drill bit currently employed for the drilling of CFC's and GRP's; Figure 2 illustrates the geometry of a dagger drill bit; Figure 3 illustrates a drill bit in accordance with the invention; Figure 4 is a perspective view of a drill bit in accordance with the invention; Figures 5 and 6 are side elevations of the drill bit of Figure 4; Figure 7 is an enlargement of portion B of Figure 5; Figure 8 is an enlargement of portion A of Figure 6; Figure 9 is an enlarged end view of the drill bit of Figures 4 to 6; and Figure 10 shows a PCD insert.</p>
<p>Detailed Description of the Drawings</p>
<p>A conventional fluted drill bit 1 comprises a body 2 with an axis of rotation 3. The cutting end of the drill has a point angle a' typically of 120 , with a cutting force shown by arrow Fl at an angle B1, being 300 to the axis 3.</p>
<p>A conventional dagger drill bit 4 is shown in Figure 2, and comprises a body 5 having an axis of rotation 6, the cutting end having dagger geometry with two 180 opposed flats 7 converging towards a point or apex 8 to define two cutting edges 9 and 10. The cutting end has a point angle 2 of 30 to the apex 8, so that the cutting force io shown by arrow F2 is at and angle B2, being 75 to the axis 6.</p>
<p>A dagger drill bit 11 as illustrated in Figures 3 to 10, has the same reference numerals as Figure 2, and in accordance with the invention, has two 180 opposed PCD inserts 12 each brazed into a receiving seat 13 of a solid carbide body 14 of diameter 2mm to 50mm, and of length 20mm to 330mm. The location and geometry of is each insert 12 provides a lower rotational speed inner zone 15 and a higher rotational speed outer zone 16.</p>
<p>The inserts 12 are of such dimensions and geometry that some 20% to 70% of the drill bit diameter D is in the PCD zone, and some 80% to 30% of the drill diameter d is of exposed carbide.</p>
<p>In detail, each insert 12 has an arcuate seating face 17 to seat on a correspondingly arcuate receiving face 18 of the seat 13, and each insert 12 also has a major cutting edge 19 extending towards the apex 8 of the drill bit 11 and a minor cutting edge 20 at the outside diameter of the body 5.</p>

Claims (2)

  1. <p>CLAIMS</p>
    <p>1. A drill bit for the drilling of holes in composite materials such as CFC's and GRP's, wherein the drill bit is of solid carbide and of dagger geometry, with 180 opposed flats converging towards an apex of the bit to define two cutting edges, with a S lower rotational speed inner zone of each cutting edge of exposed carbide, and with a higher rotational speed outer zone of each cutting edge defined by portions of two polycrystalline diamond (PCD) inserts spaced 1800 apart and brazed into respective receiving seats of the carbide of the body.</p>
    <p>o
  2. 2. A drill bit, wherein the drill bit has a 30 point angle.</p>
    <p>3. A drill bit as claimed in Claim I or Claim 2, wherein some 20% to 70% of the drill bit diameter is in the PCD zone, and some 80% to 30% of the drill diameter is of exposed carbide.</p>
    <p>4. A drill bit as claimed in any preceding claim, wherein the diameter of the drill bit is in the range of 2mm to 50mm.</p>
    <p>5. A drill bit as claimed in any preceding claim, wherein the overall length of the drill bit is in the range of 20mm to 330mm.</p>
    <p>6. A drill bit as claimed in any preceding claim, wherein each PCD insert has an arcuate seating face, to seat on a correspondingly arcuate receiving face of a recessed, receiving seat in the carbide.</p>
    <p>7. A drill bit as claimed in any preceding claim, wherein each PCD insert has a major cutting edge extending towards the apex of the drill bit, and a minor cutting edge at the outer diameter of the drill bit.</p>
    <p>8. A drill bit substantially as herein before described with reference to Figures 2 to of the accompany drawings.</p>
GB0706061A 2006-04-01 2007-03-29 Drill bit with polycrystalline diamond inserts Withdrawn GB2436723A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB0606620.3A GB0606620D0 (en) 2006-04-01 2006-04-01 Drill bit

Publications (2)

Publication Number Publication Date
GB0706061D0 GB0706061D0 (en) 2007-05-09
GB2436723A true GB2436723A (en) 2007-10-03

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GBGB0606620.3A Ceased GB0606620D0 (en) 2006-04-01 2006-04-01 Drill bit
GB0706061A Withdrawn GB2436723A (en) 2006-04-01 2007-03-29 Drill bit with polycrystalline diamond inserts

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Application Number Title Priority Date Filing Date
GBGB0606620.3A Ceased GB0606620D0 (en) 2006-04-01 2006-04-01 Drill bit

Country Status (1)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013041855A1 (en) 2011-09-19 2013-03-28 Exactaform Cutting Tools Limited Drill reamer
CN105499661A (en) * 2016-01-13 2016-04-20 江西杰浩硬质合金工具有限公司 Dagger drill with left-hand screw right edge
CN106270664A (en) * 2016-08-30 2017-01-04 大连理工大学 A kind of polycrystalline diamond compact bit with the micro-toothing of flip Trim

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115570186B (en) * 2022-11-21 2023-04-18 成都航威精密刃具有限公司 Cutter and method for inhibiting carbon fiber hole making defects

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217332A (en) * 1992-01-07 1993-06-08 Mitsubishi Materials Corporation Drill bit for advanced materials
JPH10113819A (en) * 1997-11-06 1998-05-06 Aisan Ind Co Ltd Rotary cutting tool

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5217332A (en) * 1992-01-07 1993-06-08 Mitsubishi Materials Corporation Drill bit for advanced materials
JPH10113819A (en) * 1997-11-06 1998-05-06 Aisan Ind Co Ltd Rotary cutting tool

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013041855A1 (en) 2011-09-19 2013-03-28 Exactaform Cutting Tools Limited Drill reamer
US9694432B2 (en) 2011-09-19 2017-07-04 Exactaform Cutting Tools Limited Drill reamer
CN105499661A (en) * 2016-01-13 2016-04-20 江西杰浩硬质合金工具有限公司 Dagger drill with left-hand screw right edge
CN106270664A (en) * 2016-08-30 2017-01-04 大连理工大学 A kind of polycrystalline diamond compact bit with the micro-toothing of flip Trim

Also Published As

Publication number Publication date
GB0606620D0 (en) 2006-05-10
GB0706061D0 (en) 2007-05-09

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