GB2238736A - Drill bit or corehead manufacturing process - Google Patents
Drill bit or corehead manufacturing process Download PDFInfo
- Publication number
- GB2238736A GB2238736A GB9020260A GB9020260A GB2238736A GB 2238736 A GB2238736 A GB 2238736A GB 9020260 A GB9020260 A GB 9020260A GB 9020260 A GB9020260 A GB 9020260A GB 2238736 A GB2238736 A GB 2238736A
- Authority
- GB
- United Kingdom
- Prior art keywords
- corehead
- drill bit
- bit
- shank
- wax
- 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.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- 238000000034 method Methods 0.000 claims abstract description 38
- 238000005495 investment casting Methods 0.000 claims abstract description 15
- 230000004927 fusion Effects 0.000 claims description 4
- 230000013011 mating Effects 0.000 claims description 2
- 238000005266 casting Methods 0.000 abstract description 12
- 239000012530 fluid Substances 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 6
- 230000008569 process Effects 0.000 abstract description 6
- 239000001993 wax Substances 0.000 description 22
- 238000003754 machining Methods 0.000 description 11
- 239000011159 matrix material Substances 0.000 description 11
- 229910000831 Steel Inorganic materials 0.000 description 9
- 239000010959 steel Substances 0.000 description 9
- 238000005552 hardfacing Methods 0.000 description 6
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000009434 installation Methods 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 241000237858 Gastropoda Species 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 238000010923 batch production Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- 238000007598 dipping method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000010561 standard procedure Methods 0.000 description 2
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000531 Co alloy Inorganic materials 0.000 description 1
- 229910001347 Stellite Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- AHICWQREWHDHHF-UHFFFAOYSA-N chromium;cobalt;iron;manganese;methane;molybdenum;nickel;silicon;tungsten Chemical compound C.[Si].[Cr].[Mn].[Fe].[Co].[Ni].[Mo].[W] AHICWQREWHDHHF-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
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
- E21B10/54—Drill bits characterised by wear resisting parts, e.g. diamond inserts the bit being of the rotary drag type, e.g. fork-type bits
- E21B10/55—Drill bits characterised by wear resisting parts, e.g. diamond inserts the bit being of the rotary drag type, e.g. fork-type bits with preformed cutting elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/06—Casting in, on, or around objects which form part of the product for manufacturing or repairing tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
- B23P15/28—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools
- B23P15/32—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass cutting tools twist-drills
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Earth Drilling (AREA)
Abstract
The process involves casting a hard material shell 32 which is threaded or profiled internally to allow attachment to a pre-machined shank 44 such that the advantages of a fluid and wear resistant investment casting of complex shape may be combined with a tough and machinable shank to allow attachment to the drill string. <IMAGE>
Description
"Drill Bit or Corehead Manufacturina Process"
This invention relates to a method of manufacturing petroleum/mining drill bits or coreheads with synthetic and natural diamond materials by utilising investment casting methods.
Current methods for producing drill bits/coreheads utilise a matrix or a steel body.
In the matrix type, tungsten carbide powder matrix is formed in a thick shell around a steel inner core which carries the threaded connection. The cutters are then brazed on to the pre-formed matrix shell.
This method is suitable since the tungsten carbide matrix is very resistant to fluid erosion and abrasive wear, natural diamonds can be included in the matrix shell for gauge protection, and relatively complex shapes can be produced.
However, the method suffers frbm the disadvantages that possible breakdown of bond between the matrix shell and steel core may occur, manufacture of the graphite mould is precision work requiring high labour input, and the cost is high due to the quantity of carbide required
Also, the differential of contraction between matrix shell or steel core may cause cracking especially in the larger products and further, poor quality of the matrix body formed necessitates extensive hand fettling.
In the steel body type, the normal method of manufacture is by machining from the solid using multi-axis milling machines and then hard-facing using welding or spray metal techniques prior to the installation of the cutters. These cutters are either brazed in place or pressed into prepared holes and held in place by an interference fit.
The advantages of the steel body type are a single unit construction with no possibility of break-up due to bond failure or cracking, low cost materials, and CNC multi-axis milling machine techniques give good repeatability for batch production.
However, the steel body type method is labour intensive, in that hard facing has to be applied after machining, and any surplus hardfacing has to be hand-ground away from cutter pockets prior to installation. Also, the allowable complexity of shape is restricted by limitations of machining capabilities.
It has previously not been considered a viable solution to manufacture drill bits/coreheads utilising investment casting techniques; the matrix and CNC machining approach being far more established and understood than this hitherto unknown method of manufacturing.
The accepted standard method of manufacturing an investment casting for industrial products such as aircraft turbine blades and engine components is as follows:
A master mould is manufactured to cast accurate wax males of the product required. The wax males are then coated with a ceramic material by dipping them in a slurry and then raining sand on the wet slurry. This is done a number of times, allowing the slurry and sand coating to dry before re-dipping.
In this way, a thick coating of material is built up around the wax male. The coated wax male is then furnaced to bake the coating and melt out the wax, thus creating an accurate ceramic mould of the product to be cast.
Under normal circumstances, this method of manufacture would not be used to produce a steel-bodied bit or corehead due to the fact that it would require subsequent hard facing after casting in order to withstand the fluid erosion and abrasive wear experienced downhole. The application of this hard facing by spray metal or welding techniques would cover or damage the accurately-formed profile of the investment cast product thus spoiling the dimensional accuracy and therefore defeating the purpose of using this process in the first place.
It is an object of the invention to obviate or mitigate the above disadvantages by utilising the investment casting process in a novel method of manufacture to product a highly accurate and, if required, complex casting, which needs little refinishing prior to installation of the cutters.
According to a first aspect of the present invention, there is provided a method of fabricating a drill bit.
or corehead, said method comprising the steps of forming a relatively hard outer shell by investment casting, and connecting the shell to a pre-machined bit shank.
The connection of the outer shell to the bit shank is preferably by a screw-thread connection, and the screw-thread connection is preferably locked by a mechanical lock and/or by fusion bonding of mating threaded surfaces and/or of adjacent portions of the connected components.
According to a second aspect of the present invention there is provided a drill bit or corehead, manufactured by the method according to the first aspect of the present invention.
The method of the invention combines the advantages of both matrix and steel bodied type production, substantially reducing the labour content per manufactured unit, thus greatly enhancing the possibilities of mass production.
Embodiments of the invention will now be described by way of example.
In order to achieve a product which would fulfil therequirements of the industry, it was necessary to devise a method of investment casting a hard bit body whilst retaining a tough machinable central core. This was achieved by casting the bit body utilising investment casting methods and pre-machining the bit shank; then connecting the two items together using both mechanical and fusion locking mechanisms.
According to the present method of manufacture the drill bit or corehead will be made as two separate components in a two-part manufacturing process. The purpose of producing the bit in two components is that the bit shank requires different properties to the bit head i.e.
the bit head requires - to be resistant to abrasive
wear
- to be resistant to fluid
erosion the shank requires - to be easily machinable
- to have the capability of
withstanding high
stress/fatigue levels
These properties are not realistically achievable from one material.
The complex form of a drill bit head is difficult and expensive to machine and therefore lends itself to the casting process. The bit shank on the other hand is an easily machined component which can be manufactured by most oil industry type lathes.
According to the novel manufacturing process of the present invention, the first stage is to produce an accurate male wax model of the bit head to be cast.
This can be achieved in a number of ways:
Method 1 - it can be machined from the sold piece
of wax attached to a mandrel. (This is
a particularly useful approach for
prototyping or batch production.)
Method 2 - wax injection mould dies can be
manufactured for the particular
component and injection moulded wax
males can be produced. This is
particularly suitable for mass
production.)
Method 3 - A combination of methods 1 and 2 can be
used i.e. injection mould the basic
shape and carry out minor machining on
the wax. (This allows for greater
flexibility for cutter and gauge
protection slug positioning while
maintaining the advantages of relatively
low cost mass produced waxes.)
Method 4 - Wax injection mould can be produced for
the bit in component form and these mass
produced component parts assembled at
the wax stage to produce a variety of
bits. (This allows for mass production
of a variety of products at relatively
low cost).
The second stage of manufacture is to produce a ceramic mould from the wax male which has been produced by one of the above methods.
This is done by the conventional investment casting method as previously described.
The third stage is to make an investment casting by pouring molten alloy into the prepared ceramic mould thus producing an exact copy of the original wax male.
This casting would be of a material which is highly resistant to abrasive wear and fluid erosion in its cast state, i.e. the high content cobalt alloys such as stellite
This casting would incorporate all the cutter and gauge slug pockets to a high degree of accuracy. It would also include fluid porting and nozzle positions together with an internal attachment profile such as a thread.
The fourth stage is to clean up nozzle positions and internal attachment profile after casting and NDT (non-destructive testing), by minor machining work and hand fettling.
The fifth stage is to furnace braze the cutter and gauge protection slugs into the cast head, using furnace or torch brazing techniques.
The sixth stage is to attach a pre-machined shank to the prepared bit head, make up to the required torque and mechanically lock into position.
Further embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:
Fig. 1 depicts a wax block cast onto an alloy
mandrel ready for machining;
Fig. 2 depicts a wax shell taken off the mandrel
after machining;
Fig. 3 depicts a pre-machined steel shank screwed
into the investment cast bit head; and
Fig. 4 is a perspective view of a completed drill
bit.
Referring first to Fig. 1, an alloy mandrel 10 has an attachment thread 12 formed on one end. A wax block 14 (shown in ghost outline) is cast around the thread 12 to form an assembly ready for machining to shape.
Fig. 2 shows a wax shell 16 as typically machined from the block 14, and unscrewed from the thread 12 to leave an internal attachment thread 18. The cutter shell 16 has a four-bladed form, with pockets 20 on the blade edges for subsequent mounting of cutter inserts, and side-face pockets 22 for subsequent insertion of hard inserts to maintain cutter gauge against diameter reduction by wear. As an alternative to being machined, the wax shell 16 could be formed by injection moulding.
An investment casting is then formed from the wax shell 16.
Fig. 3 shows, in vertical section, the investment casting 32 resulting from the mould 16, screwed onto a pre-machined bit shank 44 to form a two-component drill bit 42. The screw-threaded connection of the casting 32 to the shank 44 is preferably locked by mechanical locking and/or by fusion bonding.
Fig. 4 is a perspective view of the completed drill bit 42. A central conduit 48 runs from a connector 50 on the bit shank 44 through to a flow manifold chamber 52 (not visible in Fig. 4, but shown in Fig. 3) and thence to nozzles 54. PDC cutters 56 are mounted in the pre-formed cutter pockets 20 (Fig. 2) in the cutter blade edges, and hard slugs or inserts 58 (of a different shape to that provided for by the pockets 22 in Fig. 2) are fitted in pre-formed pockets in the outer edges of the blades, to act as gauge protectors.
A bit breaker slot 60 allows the temporary attachment of a spanner-like tool (not shown) for detachment of the drill bit 42 from a drill string (not shown) by unscrewing of the connector 50.
The advantages of the present invention are: - Highly accurate investment casting requires
minimum of hand grinding, machining etc, prior to
cutter installation, thus substantially reducing
labour content involved in standard method of
producing drill bits/coreheads.
- Positive locking mechanisms ensures integrity of
bond between the shank and bit head.
- Furnacing of the head without shank reduces
furnace power consumption and therefore the
overall cost.
- Mechanical locking mechanism allows for easy
recycling of high cost bit head alloy.
- Casting method allows for greater flexibility in
fluid porting.
- Casting method allows for greater flexibility in
cutter and gauge insert installation.
- Accuracy of casting gives better quality control- of cutter pockets and braze bond integrity due to
the fine clearances achievable giving good
capillary action of the braze.
- Injection moulded wax ensures consistency of
cutter positioning and therefore bit performance.
Thus has been described a method of manufacture which utilises the investment casting processes to give the degree of accuracy required for producing drill bits/corehead bodies, and enables the hard facing to be applied in a two-part manufacturing process.
Modifications of the above-described process and product can be adopted without departing from the scope of the invention.
Claims (6)
1. A method of fabricating a drill bit or corehead, said method comprising the steps of forming a relatively hard outer shell by investment casting, and connecting the shell to a pre-machined bit shank.
2. A method of fabricating a drill bit or corehead as claimed in Claim 1, wherein the connection of the outer shell to the bit shank is by a screw-thread connection.
3. A method of fabricating a drill bit or corehead as claimed in Claim 2, wherein the screw-head connection is locked by a mechanical lock and/or by fusion bonding of mating threaded surfaces and/or of adjacent portions of the connected components.
4. A drill bit or corehead, manufactured by the method according to any one of Claims 1 to 3.
5. A method of fabricating a drill bit or corehead substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
6. A drill bit or corehead manufactured by the method substantially as hereinbefore described, with reference to and as shown in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9020260A GB2238736B (en) | 1989-09-16 | 1990-09-17 | Drill bit or corehead manufacturing process |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB898921017A GB8921017D0 (en) | 1989-09-16 | 1989-09-16 | Drill bit or corehead manufacturing process |
| GB9020260A GB2238736B (en) | 1989-09-16 | 1990-09-17 | Drill bit or corehead manufacturing process |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9020260D0 GB9020260D0 (en) | 1990-10-31 |
| GB2238736A true GB2238736A (en) | 1991-06-12 |
| GB2238736B GB2238736B (en) | 1992-12-16 |
Family
ID=26295934
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9020260A Expired - Lifetime GB2238736B (en) | 1989-09-16 | 1990-09-17 | Drill bit or corehead manufacturing process |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2238736B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2345930A (en) * | 1999-01-25 | 2000-07-26 | Baker Hughes Inc | Drill bit with layer-manufactured shell integrally secured to cast core structure |
| GB2384262A (en) * | 1999-01-25 | 2003-07-23 | Baker Hughes Inc | A method of fabricating an earth-boring drill bit |
| EP3048241A1 (en) | 2015-01-23 | 2016-07-27 | Sandvik Intellectual Property AB | A rotary claw drill bit |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1549211A (en) * | 1975-06-12 | 1979-07-25 | Merz Ag | Method of making reamers |
-
1990
- 1990-09-17 GB GB9020260A patent/GB2238736B/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1549211A (en) * | 1975-06-12 | 1979-07-25 | Merz Ag | Method of making reamers |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2345930A (en) * | 1999-01-25 | 2000-07-26 | Baker Hughes Inc | Drill bit with layer-manufactured shell integrally secured to cast core structure |
| US6454030B1 (en) | 1999-01-25 | 2002-09-24 | Baker Hughes Incorporated | Drill bits and other articles of manufacture including a layer-manufactured shell integrally secured to a cast structure and methods of fabricating same |
| GB2345930B (en) * | 1999-01-25 | 2003-07-16 | Baker Hughes Inc | Earth-boring drill bit |
| GB2384262A (en) * | 1999-01-25 | 2003-07-23 | Baker Hughes Inc | A method of fabricating an earth-boring drill bit |
| GB2384262B (en) * | 1999-01-25 | 2003-09-03 | Baker Hughes Inc | Drill bits and other articles of manufacture including a layer-manufactured shell integrally secured to a cast structure and methods of fabricating same |
| US6655481B2 (en) | 1999-01-25 | 2003-12-02 | Baker Hughes Incorporated | Methods for fabricating drill bits, including assembling a bit crown and a bit body material and integrally securing the bit crown and bit body material to one another |
| EP3048241A1 (en) | 2015-01-23 | 2016-07-27 | Sandvik Intellectual Property AB | A rotary claw drill bit |
| US10781641B2 (en) | 2015-01-23 | 2020-09-22 | Sandvik Intellectual Property Ab | Rotary claw drill bit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2238736B (en) | 1992-12-16 |
| GB9020260D0 (en) | 1990-10-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20080917 |