DE102010017059A1 - Method for manufacturing main body of drilling head by infiltration of matrix material-powder discharge with inflitrant, involves arranging forming section in cavity of infiltration mold - Google Patents

Abstract

The method involves arranging a forming section in a cavity of an infiltration mold. The forming section is manufactured from a sintered ceramic that is non-oxidic ceramic mixer. The sintered ceramic has boron nitride, aluminum nitride, titanium diboride, tungsten or boron oxide. An independent claim is also included for an infiltration forming section with a casing outer surface.

Description

The invention relates to a method for producing a main body of a drill head by infiltrating a matrix material powder bed with an infiltrant according to the preamble of claim 1. Furthermore, the invention relates to an infiltration mold according to the preamble of claim 6 and an infiltration molding according to the preamble of claim 7. Furthermore The invention relates to the use of a shaping member for producing a recess in a body during manufacture of the body via infiltration of a matrix material powder bed with an infiltrant.

A method according to the preamble of claim 1, an infiltration mold according to the preamble of claim 6 and an infiltration molding member according to the preamble of claim 7 are e.g. B. off US 5,662,183 known (see there eg 3 ).

US 5,662,183 discloses a method of making a main body of a so-called PDC drill head by infiltrating a matrix material introduced into an infiltrant form, e.g. Tungsten carbide, with an infiltrant, e.g. B. a binder alloy, z. B. a copper alloy. Subsequently, so-called PCD cutting elements are soldered onto the main body produced in this way. In particular, the cutting elements are soldered into correspondingly shaped pockets or recesses which are formed in the outer surface of the main body. To form these pockets so-called. Forming parts or placeholders are placed in the infiltration mold before filling the matrix material, which keep during the infiltration process predetermined areas of the mold interior of matrix material and thereby allow the formation of the pockets on the main body outer surface.

These shaping parts are cylindrical in the prior art and made of graphite (as well as the infiltration). Once the main body formed by infiltrating the matrix material is sufficiently cooled, the infiltrant mold and forming members are separated and disassembled (eg, broken) to expose the drill head main body. Graphite residues adhering to the drill head main body outer surface, in particular graphite residues of the shaping parts adhering in the pockets, are removed in a complex mechanical reworking process. Subsequently, the cutting elements are soldered into the pockets. Mechanical reworking of the pockets is required because graphite of the forming members reacts with the infiltrant, so that the drill head main body removed from the mold has graphite cakes on its outer surface, and particularly in the pockets. However, in order to allow a stable attachment and exact positioning of the cutting body on the drill head main body, the pockets must have a certain surface quality in order to adjust the soldering gap exactly. Each bag may require a post-processing time of several minutes, wherein more than 100 cutting bodies can be arranged on a conventional PDC-drilling head, so that overall a considerable amount of mechanical post-processing may be required. Another problem of the graphite cylinders used in the prior art is the dust development during mechanical finishing, which requires appropriate measures to ensure the protection and safety of the personnel. In addition, the carbon of the graphite dissolves in certain infiltrants and thus passes into the infiltrated matrix material, which can lead to undesirable reactions:
In addition, it is known to form the placeholders for the formation of the recesses as ceramic green bodies, ie as body produced by cold pressing of particulate material. For example, silicon carbide can be used for such a green body. After demolding the drill head main body by crushing the graphite mold and pulverizing the green body, remnants of the green body mass adhering to the drill head main body exterior can be removed by sandblasting, whereby the time required for post-processing can be shortened over the use of graphite cylinders. However, during demoulding and reworking, hazardous dusts containing silicon carbide are released, which must be disposed of in a complicated manner and pose a potential hazard for the personnel.

It is an object of the invention to provide a method for producing a main body of a drill head by infiltrating a matrix material powder bed with an infiltrant, with which a drill head main body can be produced, the demolding and reworking is simplified. Further, it is an object of the invention to provide an infiltration molding member and an infiltrating mold with such an infiltration molding member, wherein the infiltration molding member enables the formation of recesses in the outer surface of the drill head main body without the need for elaborate demolding and reworking.

To this end, the invention provides a method according to claim 1, an infiltrating mold according to claim 6 and an infiltration molding member according to claim 7. Claim 9 describes the use of a shaping part for producing a recess in a body during manufacture of the body via infiltration of a matrix material. Powder bed with an infiltrant. Further embodiments are described in the dependent claims.

In the method according to the invention for producing a main body of a drill head by infiltrating a matrix material powder bed with an infiltrant introduced into a cavity of an infiltration mold, at least one molding part made of a sintered ceramic is arranged in the cavity of the infiltration mold. After infiltrating the matrix material powder bed with the infiltrant, the forming member is removed from the main body formed by the infiltrated matrix material powder bed so that a recess for receiving a cutting element is formed in the main body.

The drill head can z. B. a drill head with fixed cutting elements (in English "fixed cutter drill bit"). For example, the drill bit may be a so-called PDC drill bit. H. a drill head with multiple PCD (polycrystalline diamond PCD) cutting elements.

As a matrix powder can, for. B. a hard material powder or a hard material powder mixture can be used. Frequently, a powdered carbide or a mixture containing powdered carbide is used, wherein as carbide predominantly tungsten carbide is used. The hard material powder used and the grain size of the hard material powder used (together with the infiltrant used) determine the mechanical properties of the drill head main body, such. B. the wear behavior in the borehole. The matrix powder may also contain additives, for. B. additives for changing / adjusting the properties of the drill head main body or additives for improving the wettability of the matrix powder by the infiltrant. Such an additive may, for. B. nickel, the z. B. up to 10 wt .-% of the matrix powder can make up.

As an infiltrant or binder for the matrix material may, for. As a suitable metal or a suitable metal alloy are used, for. B. an infiltration alloy based on Cu. A typical Cu-based infiltration alloy has the name MF53 and consists of 25% by weight of Mn, 15% by weight of Ni, 8% by weight Zn, balance Cu. The melting interval of this Cu alloy is 952-1071 ° C. Other possible infiltrants are z. In US 5,662,183 described, for. As an infiltrant containing, inter alia, at least 60 wt .-% Ni and at least 8 wt .-% Co.

The infiltration can z. B. made of graphite.

However, the invention is not limited to the use of a particular matrix material or infiltrant. Likewise, the infiltration can be made of a material other than said material. In addition, the invention should also encompass such cases in which both the infiltration form and the at least one shaping part are made from a sintered ceramic. In this case, the infiltration form and the at least one shaping part can be formed either as separate parts or in one piece.

To form running in the interior of the drill head channels for the washing liquid z. B. one or more lost cores made of cast sand can be used.

In the infiltration mold according to the invention, a cavity for receiving a matrix material powder bed is arranged, in which at least one shaping part made of a sintered ceramic is arranged (eg, the at least one shaping part is partially accommodated in a depression formed by the wall surface of the cavity), wherein a recess for receiving a cutting element is formed in the main body (particularly an at least partially formed cylindrical recess in the outer surface of the main body) when forming a drill head main body by infiltrating a matrix material powder bed with an infiltrant.

The infiltration molding member of the present invention is made of a sintered ceramic and formed to form a recess for receiving a cutting element in the drill head main body from the infiltration molding member by producing a drill head main body by infiltrating a matrix material powder bed with an infiltrant.

According to another aspect of the invention, to form a recess in a body during manufacture of the body by infiltrating a matrix material powder bed with an infiltrant, a forming member made of a sintered ceramic is used. The body can z. B. be a main body of a drill head. However, the use of the sintered forming member is not limited to the formation of recesses in the production of a drill head main body. Rather, the sintered shaping part can also be used to form recesses in the production of other shaped bodies.

The molding member made of a sintered ceramic has at least one of those made of a green compact Shaping parts of the prior art increased mechanical stability, so that the shaping member is easily removable from the body formed from the infiltrated matrix material, for. B. by gentle / gentle shaking of the shaping part. Due to its high mechanical stability, the sintered shaping part can thereby be removed as a whole, ie without destruction of the shaping part, from the manufactured body, so that it can be reused to produce a further body. The forming member of the invention need not be crushed (as is common in the prior art graphite cylinders), nor does it need to be pulverized (as is the case with green compacts). In addition, the comparatively high abrasion resistance of the sintered ceramic ensures a high surface quality of the recesses to be formed and prevents carryover of material of the shaping part in the form of abrasion into the matrix material and thus the drill head main body to be manufactured, so that the shaping part according to the invention can be used in infiltration processes, where abrasive materials are used. Due to the thermal stability of the sintered ceramic at the usual infiltration temperatures decomposition of the material of the shaping part by thermal influences and / or reactions with the environment (in particular with the matrix material and the infiltrant), which can influence the properties of the body to be manufactured excluded or greatly reduced. Furthermore, the thermal stability has a positive effect on the life of the shaping part.

In addition, due to the formation of the molding part according to the invention as a sintered ceramic by suitable selection of the components of the starting powder mixture to be sintered, the chemical stability of the shaping part can be adjusted specifically. As a result, reactions of the material of the shaping part with the matrix material and / or the infiltrant (and with the material of the infiltration form) can be substantially avoided. For example, the starting powder mixture may be admixed with one or more powder components which have poor wettability with respect to the infiltrant, such that the sintered ceramic is poorly wetted by the infiltrant. Such a component may, for. B. boron nitride (BN) and / or aluminum nitride (AlN). The poor wettability favors a physical separation of the molding part and infiltrants and reduces the formation of a bond between the molding part and infiltrants, which would lead to increased effort during removal of the body and geometric inaccuracies of the demolded body and thus to a costly rework.

In the following, the shaping part will be described in more detail. The statements made in this connection relate both to the method according to the invention and to the infiltration form according to the invention, to the infiltration molding part according to the invention and to the use according to the invention.

The shaping part can, for. B. have an at least partially formed substantially cylindrical (eg., Circular cylindrical) outer shell surface. The radius of the outer shell surface is z. B. less than 2 cm, z. B. less than or equal to 1.5 cm, z. B. 2.5 mm to 1.5 cm. For example, the forming member has a substantially cylindrical shape, e.g. B. a substantially circular cylindrical shape. Several shaping parts according to the invention can either be provided individually or connected to one another. In the latter case, for. B. be formed by an integrally formed sintered body / sintered body several shaping parts. The shaping part can, for. B. in the wall surface of the cavity / be used, so that it forms an increase relative to the adjacent wall surface portions, which is complementary to the recess to be formed. This increase can z. B. be cylindrical, with an at least partially formed circular cross-sectional area or a circular sector cross-sectional area.

For example, the forming member is made of a material that is substantially non-infiltratable by the infiltrant.

For example, the sintered ceramic is a mixed ceramic, e.g. B. a non-oxide mixed ceramic, d. H. a mixed ceramic, which consists mainly of non-oxidic components.

The sintered ceramic is z. B. from or contains boron nitride (BN) and / or aluminum nitride (AlN). Both boron nitride and aluminum nitride have poor wettability by the commonly used infiltrants (typically a molten metal alloy). Aluminum nitride also has a useful mechanical strength. Therefore, according to one embodiment, the sintered ceramic consists essentially of AlN. According to another embodiment, the sintered ceramic consists essentially of a mixture of AlN and BN. If the ceramic contains other components in addition to AlN and / or BN, then AlN and / or BN are altogether z. At least 20% by weight (eg to 20-90% by weight, eg to 20-80% by weight, eg to 20-60% by weight) , The average grain size of BN and / or AlN can be z. B. 2 to 15 microns, z. B. 4 to 10 microns, amount.

For example, the sintered ceramic may contain one or more components which are selected from the group consisting of titanium diboride, tungsten and aluminum nitride. These components impart appropriate mechanical strength to the ceramic.

For example, the ceramic contains on the one hand at least one wetting-inhibiting component (BN and AlN) and on the other hand at least one strength-promoting component (AlN, TiB ₂ and W), for. B. to each 20 to 80 wt .-%, z. B. 20-60 wt .-%.

• – 20 bis 60 Gew.-% Bornitrid oder Aluminiumnitrid oder ein Gemisch aus Bornitrid und Aluminiumnitrid,
• – 15 bis 60 Gew.-% Titandiborid,
• – 0,1–5 Gew.-% Boroxid,
• – 0,1–10 Gew.-% einer sauerstoffhaltigen Verbindung, die geeignet ist, mit dem Boroxid eine Borat-Bindephase zu bilden, und
• – optional 5 bis 20 Gew.-% Wolfram.

According to one embodiment, the sintered ceramic is made from a powder mixture containing the following components (or alternatively consisting of the following components):

• 20 to 60% by weight boron nitride or aluminum nitride or a mixture of boron nitride and aluminum nitride,
• From 15 to 60% by weight of titanium diboride,
• 0.1 to 5% by weight boron oxide,
• 0.1-10% by weight of an oxygen-containing compound capable of forming a borate binder phase with the boric oxide, and
• - Optionally 5 to 20 wt .-% tungsten.

In the following the invention will be explained in more detail by means of embodiments with reference to the drawing. In the drawing show:

1 a PDC drill head,

the 2A - 2C three separate shaping parts according to the invention in a schematic representation, which are arranged in an infiltration form,

the 3A and 3B a one-piece sintered ceramic insert element in a schematic representation, which is arranged in an infiltrating mold and of which three interconnected inventive shaping parts are formed, and

4 a schematic representation of an apparatus for producing a PDC drill head as in 1 is shown.

1 shows a so-called. PDC drill head 1 (often referred to as a drill head with fixed cutting elements, in English: "fixed-cutter drill bit") as it is used in deep drilling, z. For example, in drilling for the development of oil and gas deposits. The PDC drill head 1 has a main body 3 , The main body 3 forms several fin-shaped cutting edges 5 off (in the example shown 8th To cut). Every cutting edge 5 is with several cutting elements or cutting bodies 7 Mistake. These are on the outside of each cutting edge 5 several recesses 6 formed, of which pockets for receiving the cutting body 7 are formed. The cutting body 7 are z. B. on the main body 3 or in the pockets 6 soldered. The cutting body 7 have a substantially circular cylindrical shape (eg., With a diameter of about 2-4 cm) and are designed as so-called. PCD cutting body (PKD = polycrystalline diamond). The radius of the cutting body 7 essentially corresponds to the radius of the wall surface of the recesses 6 , where the depressions 6 are cylindrical, with a cross-sectional area which forms part of the cross-sectional area of the cutting body 7 formed. The PCD cutting bodies 7 have a substantially circular cylindrical substrate 9 on, the z. B. made of tungsten carbide or other suitable carbide and that as a support for a layer 11 made of polycrystalline diamond, which faces the front of the substrate 9 is applied. The main body 3 is with an in 1 Not shown steel shank connected (this is the steel shaft during the production of the main body described below 3 arranged in the matrix material powder bed). The steel shaft is threaded. About the steel shaft, the drill head 1 connected to the drill string and driven over this.

The main body 3 (including the cutting 5 ) of the drill head 1 is prepared by infiltration of a so-called matrix powder with an infiltrant. The PCD cutting bodies 7 are usually added later on the main body 3 applied, by inserting and soldering the cutting body 7 in through the recesses 6 on the outer surface of the main body 3 formed pockets. To form the recesses 6 in the outer surface of the main body 3 For example, in the infiltration process, dummy formative members are used which are introduced into the infiltrant mold prior to introduction of the matrix powder, thus freeing the space of matrix material needed for the wells.

Unlike in the prior art, where molding parts made of graphite or a silicon carbide green body mass are used, according to the invention molding parts made of a sintered ceramic are used.

The 2A - 2C show a first embodiment of three inventive molding parts 20 , According to this embodiment, for each recess to be formed 6 exactly one shaping part 20 provided. The shaping parts 20 have according to this embodiment, a substantially circular cylindrical shape. According to this embodiment, the shaping parts 20 integrally formed (alternatively, the shaping parts 20 be formed in several parts, wherein the one-piece design is preferred). In the wall surface of the infiltration form 22 formed cavity 23 are cylindrical wells with a Circular segment cross-sectional area (eg semicircular cylindrical depressions) for partially accommodating the shaping parts 20 educated. The shaping parts 20 are with a suitable adhesive 26 fixed in the cylindrical recesses. The shaping parts received in the recesses 20 form opposite the adjacent wall surface portions of the cavity 23 a cylindrical elevation, the cross-sectional area of which results from the circular cylinder cross-sectional area of the shaping part minus the circular segment area received in the recess. In other words, that of the molding part 20 formed elevation a partially formed substantially circular cylindrical shell outer surface. The depressions formed by these elevations 6 in the drill head main body outer surface are complementary to the described elevations, ie the depressions 6 have a partially formed substantially circular cylindrical shape (see. 1 ). The radius of the depressions 6 corresponds essentially to the radius of the shaping parts 20 or the radius of the shaping parts 20 formed elevations (and also substantially the radius of the cutting elements or the substrate thereof). The radius of the depressions 6 or the increases may, for. B. less than 2 cm, z. B. less than or equal to 1.5 cm, z. B. 2.5 mm to 1.5 cm. In the 2 B and 2C denotes the reference numeral 24 the matrix material powder bed.

The 3A and 3B show a second embodiment of three inventive molding parts 20 , Also according to this embodiment is for each recess to be formed 6 exactly one shaping part 20 provided. However, there are several shaping parts 20 (three according to this embodiment) via a common web or bridge and to form a one-piece ceramic insert element 21 connected with each other. From the interconnected shaping parts 20 are - as of the substantially circular cylindrical shaping parts of the first embodiment - with respect to the adjacent wall surface portions of the cavity 23 formed cylindrical elevations whose respective cross-sectional area has the shape of a partially formed circular surface or a circular sector. The radius of the forming elements 20 formed increases, as in the first embodiment z. B. less than 2 cm, z. B. less than or equal to 1.5 cm, z. B. 2.5 mm to 1.5 cm. The integrally formed ceramic insert element 21 is in a corresponding depression in the wall surface of the cavity 23 taken and with an adhesive 26 fixed in the recess. For example, that of the ceramic insert 21 formed number of shaping parts 20 the number of wells 6 along / on one of the cutting edges 5 of the drill head main body 3 correspond, ie the ceramic insert element 21 then forms the negative structure of all pockets of a cutting edge 5 out. According to an embodiment, not shown, then each cutting edge 5 of the drill head main body 3 exactly one ceramic insert element 21 intended.

The manufacturing technique provides a variety of inter-compatible manufacturing pathways to produce the sintered ceramic forming members of the present invention. The choice of the route will depend largely on economic aspects with regard to the complexity of the required geometry and batch sizes.

For example, from a starting powder mixture, first a green body may be formed, e.g. B. by uniaxial or cold isostatic pressing the starting powder mixture. The green body may, for. B. near-net shape, d. H. with Schwundaufmass, to be pressed. Alternatively, z. B. blocks (eg., With dimensions of 300 × 400 mm) are pressed. Such a pressed block can either serve as Sinterhalbzeug or further processed before sintering in the green state and be brought into a near-net shape geometry. However, it is also possible to fill a sintering tool directly with the starting powder mixture, so that the green body production can be omitted.

The sintering of the green compact or of the starting powder mixture directly filled in the sintering tool can, for. B. done by uniaxial hot pressing. The sintering temperature can z. B. between 1800 and 2000 ° C. In the presence of a green body can also be sintered freely in the oven, ie without the presence of an all-round shape contact between the workpiece / green body and furnace / sintering tool. In the green body can during sintering while auxiliary elements such. B. centering mandrels are used. The furnace environment can consist of a variety of gases. The pressure conditions can range from a few 10 ^-5 bar up to 100 bar. High pressure may be required to achieve adequate pore-freeness for certain material compositions. Typically, the liquid phase sintering in the pressure range <1 bar, preferably <100 mbar, carried out, the application of 100 bar, preferably 80 bar, serves the subsequent densification in the presence of a liquid phase.

When sintering blocks, the shaping parts can be mechanically machined out of the finished sintered block. Depending on the requirements, reworking to the required final dimensions as well as a required surface finish may occur for all process paths.

In the sintered ceramic, individual particles / particles of the starting powder mixture are over formed between the particles sintered bridges or sintered necks and possibly held together via a binder phase. The binder phase may be oxygenated, e.g. B. be an alkaline earth borate binder phase.

• – 15 bis 60 Gew.-% (z. B. 15 bis 50 Gew.-%, z. B. 30 bis 50 Gew.-%) Titandiborid (TiB₂) mit einer mittleren Korngröße, von 2 bis 100 μm (z. B. 4 bis 20 μm, z. B. 4–7 μm) als eine erste Hauptkomponente,
• – 20 bis 60 Gew.-% (z. B. 45 bis 55 Gew.-%) Bornitrid (BN) mit einer mittleren Korngröße von 2 bis 15' μm (z. B. 4 bis 10 μm) als eine zweite Hauptkomponente,
• – wobei das Bornitrid teilweise durch Aluminiumnitrid ersetzt sein kann,
• – wobei das Bornitrid und/oder das Titandiborid Boroxid (B₂O₃) als Verunreinigungen enthalten (insgesamt 0,1 bis 5 Gew.-%),
• – 0,01 bis 10 Gew.-% (z. B. 0,1–8 Gew.-%, z. B. 1–6 Gew.-%) einer sauerstoffhaltigen Verbindung bzw. eines Gemischs aus sauerstoffhaltigen Verbindungen, welche(s) geeignet ist,

während des Heißpressens zusammen mit dem Boroxid eine Borat-Bindephase auszubilden. Die mittlere Korngröße der sauerstoffhaltigen Verbindung(en) kann z. B. 0,01 bis 10 μm betragen, z. B. 0,1 bis 5 μm. Die sauerstoffhaltige Verbindung bzw. das Gemisch kann zum Beispiel ausgewählt sein aus der Gruppe, welche besteht aus Oxiden, Carbonaten oder Hydroxiden der Alkalimetalle und Erdalkalimetalle, Übergangsmetalle der 4. bis 12. Gruppe, Metalle und Halbmetalle der 13. und 14. Hauptgruppe und des Phosphors (Polyphosphat Na(PO₃)x).According to one embodiment, the shaping parts according to the invention are formed by molding a green body from a powder mixture and then sintering the green body at a temperature of about 1900 ° C. and a maximum pressure of 100-200 bar, the powder mixture comprising:

• 15 to 60% by weight (eg 15 to 50% by weight, eg 30 to 50% by weight) of titanium diboride (TiB ₂ ) having an average particle size of 2 to 100 μm (z B. 4 to 20 microns, for example 4-7 microns) as a first main component,
• From 20 to 60% by weight (eg 45 to 55% by weight) of boron nitride (BN) having an average particle size of 2 to 15 μm (for example 4 to 10 μm) as a second main component,
• Wherein the boron nitride may be partially replaced by aluminum nitride,
• Wherein the boron nitride and / or the titanium diboride contain boron oxide (B ₂ O ₃ ) as impurities (in total from 0.1 to 5% by weight),
• 0.01 to 10% by weight (eg 0.1-8% by weight, eg 1-6% by weight) of an oxygen-containing compound or of a mixture of oxygen-containing compounds which ( s) is suitable,

form a borate binder phase during hot pressing together with the boron oxide. The mean grain size of the oxygen-containing compound (s) may, for. B. 0.01 to 10 microns, z. B. 0.1 to 5 microns. The oxygen-containing compound or mixture may be selected, for example, from the group consisting of oxides, carbonates or hydroxides of the alkali metals and alkaline earth metals, transition metals of the 4th to 12th group, metals and semimetals of the 13th and 14th main group and Phosphorus (polyphosphate Na (PO ₃ ) x).

• – wobei die Mischung optional 5 bis 20 Gew.-% (z. B. 7 bis 20 Gew.-%, z. B. 10 bis 20 Gew.-%) Wolfram mit einer mittleren Korngröße von kleiner gleich 20 μm (z. B. 0,4 bis 20 μm) enthalten kann, und
• – wobei optional sauerstoffhaltige Komponenten wie z. B. ZrO₂ sowie Verunreinigungen (wie z. B. bis zu 1 Gew.-% Eisen) in der Pulvermischung enthalten sein können.

In particular, the oxygen-containing compound z. Example, an oxide of sodium, potassium, calcium, magnesium, zinc, strontium, iron, aluminum, titanium or zirconium and a combination of at least two of these oxides. For example, the oxygen-containing compound may be calcium oxide and / or magnesium oxide and / or titanium oxide and / or aluminum oxide, e.g. For example, calcium oxide and / or titanium oxide.

• - wherein the mixture optionally 5 to 20 wt .-% (eg 7 to 20 wt .-%, eg 10 to 20 wt .-%) of tungsten having a mean grain size of less than or equal to 20 microns (z. B. 0.4 to 20 microns), and
• - Where optionally oxygen-containing components such. ZrO ₂ and impurities (such as up to 1 wt .-% iron) may be included in the powder mixture.

In the ceramic produced by sintering of this powder mixture, individual particles of the starting powder mixture are connected via sintered bridges formed between the particles. Furthermore, the particles are held together via the borate binder phase.

The boron nitride mainly contributes to poor wettability of the shaping part by the infiltrant, whereas titanium diboride v. a. is added to obtain an appropriate mechanical strength of the shaping part. The optionally added aluminum nitride and / or tungsten impart mechanical strength to the ceramic, respectively. Aluminum nitride is also poorly wetted by metal melts.

4 shows a schematic representation of a device 100 for producing a main body 3 a PDC drill head 1 as he in 1 is shown.

The device 100 has an infiltration form 22 on, which is made of graphite. The infiltration form 22 can consist of several parts, for example. The individual parts can z. B. be made by milling a graphite block. The infiltration form 22 is designed as a disposable mold, the demolding of the drill head main body 3 is decomposed, for. B. is smashed. From the infiltration form 22 becomes a cavity 23 formed, the wall surface is formed complementary to the drill head main body outer surface. The infiltration form 22 is in a reusable frame 36 taken, which is also made of graphite.

Before filling the matrix powder 24 be several inventive molding parts 20 in the cavity 23 placed (in 4 For reasons of clarity, only three shaping parts are used 20 shown), at those locations where on the drill head main body depressions 6 to be trained. The shaping parts 20 are housed in depressions that are in the wall surface of the cavity 23 are formed. The shaping parts 20 can z. B. inserted or pressed into the wells. If necessary, the shaping parts 20 be fixed in the wells with a suitable adhesive. The in the wall surface of the cavity 23 used shaping parts 20 may also be referred to as infiltrating mold inserts or wall panels which form part of the wall surface surrounding the powder bed. The shaping parts 20 keep the space free for the on the outside surface of the drill head main carrier 3 formed pockets for receiving the cutting elements 7 is needed. Therefore, the shaping parts 20 Also referred to as a pocket placeholder or cutting element placeholder. Every molding part 20 has a circular cylindrical shell outer surface whose radius is substantially that of the cutting element 7 equivalent.

Further, before filling the matrix powder 24 one or more cores 34 arranged in the cavity, of which channels are formed or kept free for the rinsing liquid. The at least one core 34 can z. B. be formed as a lost core and z. B. be made of cast sand.

In addition, a steel shaft 32 into the cavity 23 brought in. The steel shaft 32 has a thread, not shown, over which the drill head 3 for driving the same can be connected to the drill pipe. The thread may be before or after infiltration of the matrix material powder bed 24 be formed.

After introduction of the shaping parts 20 , the core 34 and the steel shaft 32 into the cavity 23 , the cavity becomes 23 with matrix powder 24 filled. The of the matrix powder 24 formed matrix material powder bed can, for. B. may be formed of several layers having a different composition and / or grain size distribution to the drill head main body 3 to give appropriate properties. The lowest layer 24 ' forms the front of the later main body 3 from and contains or consists of z. B. tungsten carbide. The lowest layer 24 ' is made of a particularly hard and abrasion resistant material. The overlying body layer 24 '' may also contain tungsten carbide or consist of tungsten carbide. The shoulder layer 24 '' can z. B. tungsten and / or tungsten carbide or contain tungsten and / or tungsten carbide. The steel shaft 32 dives into the shoulder layer 24 '' and the body layer 24 '' one.

To the matrix material powder bed 24 evenly in the cavity 23 can be distributed and condensed to a certain level, the infiltration 22 be vibrated.

Above the matrix material powder bed 24 are pieces 28 a serving as an infiltrant copper alloy arranged. In the molten state, the copper alloy flows into the cavity via an optional delivery system, not shown 23 to the matrix material powder bed 24 to infiltrate and thereby "stick together". In the unmelted state of the copper alloy are the pieces 28 over plugs 30 from the feeding system, not shown, and the matrix material powder bed 24 separated. The plugs 30 are made of a material having a melting point equal to or slightly greater than that of the copper alloy. Alternatively, the pieces can 28 also directly on the uppermost layer of the powder bed 24 be hung up. Instead of a copper alloy z. As a nickel alloy as in US 5,662,183 is described used. The ceramic sintered from the powder mixture described above, from which the shaping parts 20 exist, is also opposite to in US 5,662,183 described infiltration alloys chemically resistant and is poorly wetted by these. However, if such an alloy is used, it may be necessary to use the infiltration mold made of graphite 22 or their cavity 23 to be provided with a protective layer. Alternatively, also the infiltration form 22 be made of a sintered ceramic, z. B. from the same ceramic as the shaping parts 20 , In this case, the shaping parts 20 also of the infiltration form 22 be formed, in particular of the wall surface of the cavity 23 ,

The ratio of matrix powder to infiltrant can z. B. as in US 5,662,183 be set described, for. B. about 60 vol .-% matrix powder to about 40 vol .-% infiltrant.

The whole arrangement 100 is then placed in an oven and heated to a temperature (eg, to a temperature of about 1000 ° C) that is above the melting point of the copper alloy and the melting point of the plug material, such that the copper alloy melts and over the not shown Feeding system in the cavity 23 flows. Due to gravity and capillary forces, the molten copper alloy flows down and infiltrates the entire powder bed 24 , causing the particles of powder bed 24 be connected / glued together.

Suitable devices and methods for heating the infiltration form, the matrix material and the infiltrant and for cooling the infiltrated matrix material are, for. In US 6,220,117 B1 described.

After the infiltrated powder bed has cooled sufficiently, the drill head main body formed by the infiltrated powder bed may 3 be removed from the mold. For this purpose, first the frame 36 from the infiltration form 22 away. Subsequently, the infiltration form 22 smashed, and the shaping elements 20 be of the infiltration form 22 and the drill head main body 3 removed, if necessary z. B. by a slight shaking of the shaping elements 20 , The shaping elements 20 usually remain as a whole and can be reused in another infiltration process. Damaged forming elements 20 are easy to dispose of, as they break in the event of destruction to form a very small number of parts, with virtually no dust is released, and since in the ceramic no toxic substances are included.

After removal of the forming members, no appreciable caking / adhesions of ceramic material in the pockets of the drill head main body and no adherence of matrix material and / or the infiltrant to the forming members were noted.

The of the shaping elements according to the invention 20 kept / trained pockets have such a high surface quality that the PCD cutting inserts 7 usually without the need for elaborate post-processing of the bags can be soldered into this. The post-processing of the pockets can thus either be completely eliminated or compared to the post-processing required in the prior art greatly simplified.

The easy releasability / removability of the molding parts 20 and the greatly reduced post-processing costs are attributable to the thermal and mechanical stability of the ceramic, the high abrasion resistance of the ceramic to the powder bed, the chemical stability to the powder bed and the infiltrant and the poor wettability of the ceramic by the infiltrant.

Before soldering on the cutting elements 7 For example, in order to reduce wear during operation, the drill head main body can still be partially reinforced.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• US 5662183 [0002, 0003, 0010, 0053, 0053, 0054]
• US 6220117 B1 [0056]

Claims (10)

Method for producing a main body ( 3 ) of a drill head ( 1 ) by infiltration into a cavity ( 23 ) of an infiltration ( 22 ) introduced matrix material powder bed ( 24 ) with an infiltrant ( 28 ), where in the cavity ( 23 ) of the infiltration ( 22 ) at least one shaping part ( 20 ), which, after infiltrating the matrix material powder bed ( 24 ) with the infiltrant ( 28 ), from the main body formed by the infiltrated matrix material powder bed ( 3 ) is removed so that in the main body ( 3 ) a recess ( 6 ) for receiving a cutting element ( 7 ) is formed, characterized in that the at least one shaping part ( 20 ) is made of a sintered ceramic. The method of claim 1, wherein the sintered ceramic is a non-oxide mixed ceramic. Method according to claim 1 or 2, wherein the sintered ceramic contains boron nitride and / or aluminum nitride or consists of boron nitride and / or aluminum nitride. The method of any one of claims 1 to 3, wherein the sintered ceramic contains one or more components selected from the group consisting of titanium diboride, tungsten, and aluminum nitride. Method according to one of claims 1 to 4, wherein the sintered ceramic is made of a powder mixture containing the following components: 20 to 60% by weight boron nitride or aluminum nitride or a mixture of boron nitride and aluminum nitride, From 15 to 60% by weight of titanium diboride, 0.1 to 5% by weight boron oxide, 0.1-10% by weight of an oxygen-containing compound capable of forming a borate binder phase with the boric oxide, and - Optionally 5 to 20 wt .-% tungsten. Infiltration form ( 22 ) for use in the method according to one of claims 1 to 5, of which a cavity ( 23 ) for receiving a matrix material powder bed ( 24 ) is formed, in the at least one shaping part ( 20 ), from which, during manufacture of the main body ( 3 ) via infiltration of the matrix material powder bed ( 24 ) with an infiltrant ( 28 ) a recess ( 6 ) for receiving a cutting element ( 7 ) in the main body ( 3 ) is formed, characterized in that the at least one shaping part ( 20 ) is made of a sintered ceramic. Infiltration molding part ( 20 ) for use in the method according to one of claims 1 to 5, which is designed such that of the infiltration molding part ( 20 ) during manufacture of the main body ( 3 ) via infiltration of a matrix material powder bed ( 24 ) with an infiltrant ( 28 ) a recess ( 6 ) for receiving a cutting element ( 7 ) in the main body ( 3 ) is formed, characterized in that the infiltration molding part ( 20 ) is made of a sintered ceramic. Infiltration molding part ( 20 ) according to claim 7, which has an at least partially formed substantially circular cylindrical shell outer surface. Use of a shaping part ( 20 ), which is made of a sintered ceramic, for producing a recess in a body in the manufacture of the body via infiltration of a matrix material powder bed ( 24 ) with an infiltrant ( 28 ). Use according to claim 9, wherein the body is a main body ( 3 ) of a drill head ( 1 ).

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