EP0197741A2 - Drehbohrmeissel und Verfahren zu deren Herstellung - Google Patents

Drehbohrmeissel und Verfahren zu deren Herstellung Download PDF

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Publication number
EP0197741A2
EP0197741A2 EP86302375A EP86302375A EP0197741A2 EP 0197741 A2 EP0197741 A2 EP 0197741A2 EP 86302375 A EP86302375 A EP 86302375A EP 86302375 A EP86302375 A EP 86302375A EP 0197741 A2 EP0197741 A2 EP 0197741A2
Authority
EP
European Patent Office
Prior art keywords
cast iron
mould
bit body
bit
hardened
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Withdrawn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
EP86302375A
Other languages
English (en)
French (fr)
Other versions
EP0197741A3 (de
Inventor
Nigel Dennis Griffin
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.)
Camco Drilling Group Ltd
Original Assignee
NL Petroleum Products Ltd
Reed Tool Co 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 NL Petroleum Products Ltd, Reed Tool Co Ltd filed Critical NL Petroleum Products Ltd
Publication of EP0197741A2 publication Critical patent/EP0197741A2/de
Publication of EP0197741A3 publication Critical patent/EP0197741A3/de
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
    • E21B10/56—Button-type inserts
    • E21B10/567—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/20—Measures not previously mentioned for influencing the grain structure or texture; Selection of compositions therefor
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts

Definitions

  • the invention relates to rotary drill bits for use in drilling or coring deep holes in subsurface formations.
  • the invention is applicable to rotary drill bits of the kind comprising a bit body having an external surface on which are mounted a plurality of cutting elements for cutting or abrading the formation, and an inner passage for supplying drilling fluid to one or more nozzles at the -external surface of the bit.
  • the nozzles are so located at the surface of the bit body that drilling fluid emerging from the nozzles flows past the cutting elements, during drilling, so as to cool and/or clean them.
  • the cutting elements may be in the form of so-called "preform" cutting elements in the shape of a tablet, often circular, having a superhard cutting face formed of polycrystalline diamond or other superhard material.
  • bit body is machined from steel and the surface of the bit body is formed with sockets which receive pegs or studs on which the cutting elements are mounted.
  • bit body is formed by a powder metallurgy process in which a hollow mould is first formed, for example from graphite, in the configuration of the bit body. The mould is packed with powdered material such as tungsten carbide, usually around a steel blank, and the powdered material is then infiltrated with a metal alloy in a furnace so as to form a hard matrix. If the cutting elements are of a kind which are not thermally stable at the infiltration temperature, formers are mounted on the interior surface of the mould so as to define in the finished bit body sockets or other locations where cutting elements may be subsequently mounted.
  • Steel bodied bits are generally simpler and cheaper to manufacture than matrix bodied bits. However, they are more susceptible to erosion during drilling and, for this reason, they are sometimes provided with a hard surface coating, for example of tungsten carbide, which adds to the complexity and cost of production.
  • Matrix bodied bits are more resistant to erosion, their manufacture is complex and costly due largely to the high material cost and to the additional processes involved. Matrix bodied bits also may be made with the matrix at the surface more erosion resistant than that inside the bit body.
  • the present invention sets out to provide a new method of manufacturing a rotary drill bit using cast iron, in which at least some of the disadvantages of the known steel-bodied and matrix-bodied bits may be overcomes
  • British Patent Specification No. 1,574,884 discloses the use of cast iron in the manufacture of cutting bodies suitable for working or cutting material, such as cutting tips or inserts in rock drilling or chip forming machines. In such products it is necessary for surface portions of the product to be sufficiently hard to be resistant to erosion and damage during use of the product.
  • Specification No. 1,574,884 describes a method of providing a hard surface which requires the encasting of a hard metal, such as a sintered hard carbide, e.g. tungsten carbide, in the cast iron. Such methods have not, however, proved satisfactory in practice due to the high cost of the process and the difficulties of ensuring that the carbide is securely bonded within the cast iron.
  • U.S. Patent Specification No. 4,499,795 describes the use of cast iron in the manufacture of a rotary drill bit.
  • the inner surface of a mould is packed or coated over selected portions with particles of sintered tungsten carbide or similar sintered refractory hard metal and then cast iron is melted and poured into the mould.
  • the hard surface of the finished bit is provided by tungsten carbide.
  • the present invention provides methods of manufacturing a rotary drill bit using cast iron where the cast iron itself forms the necessary hardened surface portions of the drill bit, the steps of the method being such as to effect the necessary hardening of the cast iron during the casting process.
  • a method of manufacturing a rotary drill bit comprising forming a hollow mould in the configuration of at least a portion of the bit body, and casting said portion of the bit body in the mould by a casting process which includes the steps of pouring moulten cast iron into the mould and then cooling in the mould so that the cast iron solidifies to form said portion of the bit body, the method including the further step of subjecting the cast iron to treatment, during said casting process, which results in at least one surface portion of the cast iron bit body becoming hardened.
  • Said hardening treatment may comprise adding to at least part of the molten cast iron, before it is poured into the mould, an iron carbide-forming additive, whereby said part of the cast iron, upon solidification, contains massive inclusions of cementite.
  • Said additive may comprise boron or tellurium. Approximately 1 / 2 % of additive may be added to the molten cast iron.
  • the molten cast iron may be poured into the mould in two successive pourings, said additive being added only to the cast iron in the first pouring so as to harden only the portion of the bit body which is lowermost in the mould.
  • said hardening treatment comprises the-step of chill hardening a portion of the surface of the bit body by accelerated cooling of said surface portion during the solidification part of the casting process, said accelerated cooling being at a rate to produce massive inclusions of cementite in the solidified surface portion.
  • Said chill hardening may be effected by locating a metal heat sink in the mould adjacent said surface portion of the bit body which is to be hardened.
  • formers which project into the mould cavity so as to form sockets in the solidified cast iron bit body, said formers being in close thermal contact with said metal heat sink, whereby the interior of each socket is chill hardened.
  • said hardening treatment comprises the step, before pouring the cast iron into the mould, of coating at least part of the interior surface of the mould with a material which reacts with the cast iron, during solidification thereof, to form massive inclusions of cementite in at least one surface portion of the bit body.
  • Said coating material may be tellurium.
  • said hardening treatment comprises controlling the rate of cooling of the bit body, after solidification of the cast iron and during the subsequent cooling portion of the casting process, in such manner as to effect the formation of martensite in at least one surface portion of the bit body.
  • the invention includes within its scope a rotary drill bit comprising a bit body having an external surface on which are mounted a plurality of cutting elements for cutting or abrading the formation being drilled, a number of nozzles at the external surface of the bit, and an inner passage for supplying drilling fluid to the nozzles, at least a portion of the bit body being formed from cast iron and at least a part of the -surface of the cast iron being hardened during the casting process.
  • a drill bit manufactured according to the methods of the invention it is preferably those parts of the bit body which are particularly subject to erosion during drilling, for examples the areas around the nozzles and cutting elements, which are hardened to increase their resistance to such erosion.
  • the rest of the bit body may be accurately machined or otherwise worked after it has been cast.
  • the present invention may combine the simplicity of manufacture of steel bodied bits with the erosion resistance of matrix bodied bits and, indeed, the erosion resistance of a drill bit according to the invention will be superior to that of a steel bodied bit and may also be superior to that of a matrix bodied bit.
  • the body 10 of the drill bit is formed of cast iron by the method to be described, and has a threaded shank 11 at one end for connection to the drill string.
  • the operative end face 12 of the bit body is formed with a number of blades 13 radiating from the central area of the bit, and the blades carry cutting structures 14 spaced apart along the length thereof.
  • the bit has a gauge section including kickers 16 which contact the wall of the borehole to stabilise the bit in the borehole.
  • a central passage (not shown) in the bit body and shank delivers drilling fluid through nozzles 17 in the end face 12 in known manner to clean and/or cool the cutting elements.
  • each cutting structure 14 comprises a preform cutting element mounted on a carrier in the form of a stud which is located in a socket in the bit body.
  • each preform cutting element is circular and comprises a thin facing layer of -polycrystalline diamond bonded to -a backing layer of tungsten carbide.
  • this is only one example of the many possible variations of the type of bit to which the invention is applicable, including bits where each preform cutting element comprises a unitary layer of thermally stable polycrystalline diamond material.
  • Figure 3 illustrates a method of manufacturing a bit body of the kind shown in Figures 1 and 2.
  • a two-part mould 19- is formed from suitable material, such as sand.
  • the two-part mould comprises an upper part 20 and a lower part 21 which between them define a mould cavity 22.
  • the mould cavity has an internal configuration corresponding generally to the required surface shape of the bit body or a portion thereof.
  • a passage 23 is formed in the upper mould part 20 and leads to the mould cavity 22 from a pouring chamber 24 at the upper surface of the mould part 20.
  • the mould may be formed with elongate recesses corresponding to the blades 13 of the drill bit. Spaced apart along each blade forming recess will be a plurality of sockets each of which receives a cylindrical former (not shown), the object of the formers being to define in the bit body sockets to receive the studs on which the cutting elements are mounted. Accordingly, the formers will be of the same cross-sectional shape as the studs,--for example circular or rectangular.
  • a socket which receives one end of an elongate former (not shown) which extends into the mould space so as to form in the bit body a socket in which a nozzle may be subsequently inserted.
  • cast iron is melted and poured into the mould via the chamber 24 and passage 23. While the cast iron is molten and before it is is poured into the mould, there is added to the molten cast iron an additive having the property of causing iron carbide (cementite) to be formed in the cast iron during solidification. Suitable additives are boron and tellurium and approximately 1 / 2 % of additive may be added to the molten cast iron.
  • the mould cavity 22 After the mould cavity 22 has been filled with the molten cast iron with the additive, the mould is allowed to cool and by the time solidification of the cast iron has occurred, the additive will have caused the inclusion of massive bodies of cementite in the cast iron, thus substantially hardening the cast iron.
  • the cast iron is poured into the mould in two portions.
  • the first portion contains the boron or tellurium additive and is sufficient to fill only the bottom of the mould-up to a certain level, as indicated for example by the line 25 in Figure 3.
  • the remainder of the mould cavity is then filled with cast iron .without the additive.
  • only the lower surface portion of the body will be hardened by the inclusion of massive cementite.
  • the internal surface of the mould cavity is coated, before introduction of the molten cast iron into the mould, with a material which reacts with the cast iron, during solidification, to effect surface hardening thereof by the production of massive inclusions of cementite.
  • a suitable material is a wash of tellurium over the interior surface of the mould or a part thereof.
  • the hardening of the cast iron is effected by controlling the rate of cooling of the bit body after solidification has occurred.
  • suitable controlling of the rate of cooling of the mould will result in the production of martensite which has the effect of hardening the cast iron.
  • the lower part 21 of the mould is provided with a heat sink in the form of a chill plate 26.
  • chill hardening As is well known, in chill hardening the production of massive inclusions of cementite in the cast iron occurs.
  • the chilling at the-surface of the bit body effected by the chill plate 26 is at a rate sufficient to cause the formation of cementite (iron carbide) so that at the surface itself, the material is almost entirely composed of cementite, the proportion of cementite decreasing with distance inwardly from the chilled surface.
  • cementite iron carbide
  • cast iron preferably comprises a spheroidal graphite cast iron in which, in known manner, graphite is precipitated in nodular form by the addition of magnesium or some other suitable material.
  • the cast iron may be of the type known as "grey" cast iron, or may be compacted graphite cast iron containing titanium or some other material.

Landscapes

  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Earth Drilling (AREA)
  • Heat Treatment Of Articles (AREA)
EP86302375A 1985-04-02 1986-04-01 Drehbohrmeissel und Verfahren zu deren Herstellung Withdrawn EP0197741A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB858508622A GB8508622D0 (en) 1985-04-02 1985-04-02 Rotary drill bits
GB8508622 1985-04-02

Publications (2)

Publication Number Publication Date
EP0197741A2 true EP0197741A2 (de) 1986-10-15
EP0197741A3 EP0197741A3 (de) 1988-03-16

Family

ID=10577095

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86302375A Withdrawn EP0197741A3 (de) 1985-04-02 1986-04-01 Drehbohrmeissel und Verfahren zu deren Herstellung

Country Status (3)

Country Link
EP (1) EP0197741A3 (de)
CA (1) CA1256423A (de)
GB (1) GB8508622D0 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2793174A1 (fr) * 1999-05-07 2000-11-10 Renault Procede et dispositif pour la realisation par moulage d'une culasse de moteur a combustion interne
WO2002005986A2 (en) * 2000-07-17 2002-01-24 Consolidated Engineering Company, Inc. Method and apparatus for chill casting
CN103273042A (zh) * 2013-05-24 2013-09-04 成都工业学院 一种碳化钒钛合金钻井钻头的制造方法
CN108588768A (zh) * 2018-05-29 2018-09-28 广州市华番盛化工科技有限公司 钢铁件碱性深孔镀镍添加剂、预镀液及预镀工艺

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4029140A (en) * 1975-04-01 1977-06-14 The British Cast Iron Research Association Method of and means for obtaining white cast iron
JPS5575874A (en) * 1978-11-30 1980-06-07 Yanmar Diesel Engine Co Ltd Production of tough cast iron casting
WO1984000385A1 (en) * 1982-07-19 1984-02-02 Giw Ind Inc Abrasive resistant white cast iron
US4499795A (en) * 1983-09-23 1985-02-19 Strata Bit Corporation Method of drill bit manufacture

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4029140A (en) * 1975-04-01 1977-06-14 The British Cast Iron Research Association Method of and means for obtaining white cast iron
JPS5575874A (en) * 1978-11-30 1980-06-07 Yanmar Diesel Engine Co Ltd Production of tough cast iron casting
WO1984000385A1 (en) * 1982-07-19 1984-02-02 Giw Ind Inc Abrasive resistant white cast iron
US4499795A (en) * 1983-09-23 1985-02-19 Strata Bit Corporation Method of drill bit manufacture

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
MACHINE DESIGN, vol. 55, no. 8, April 1983, pages 10-12,22, Cleveland, Ohio, US; "The five types of cast iron" *
PATENT ABSTRACTS OF JAPAN, vol. 4, no. 116, (M-27)(598), 19th August 1980; & JP-A-55-075874 (YANMAR DIESEL ENGINE K.K.) 07-06-1980 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2793174A1 (fr) * 1999-05-07 2000-11-10 Renault Procede et dispositif pour la realisation par moulage d'une culasse de moteur a combustion interne
WO2002005986A2 (en) * 2000-07-17 2002-01-24 Consolidated Engineering Company, Inc. Method and apparatus for chill casting
WO2002005986A3 (en) * 2000-07-17 2002-05-16 Cons Eng Co Inc Method and apparatus for chill casting
US6588487B2 (en) 2000-07-17 2003-07-08 Consolidated Engineering Company, Inc. Methods and apparatus for utilization of chills for casting
CN103273042A (zh) * 2013-05-24 2013-09-04 成都工业学院 一种碳化钒钛合金钻井钻头的制造方法
CN108588768A (zh) * 2018-05-29 2018-09-28 广州市华番盛化工科技有限公司 钢铁件碱性深孔镀镍添加剂、预镀液及预镀工艺

Also Published As

Publication number Publication date
GB8508622D0 (en) 1985-05-09
EP0197741A3 (de) 1988-03-16
CA1256423A (en) 1989-06-27

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