JPH0224605B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a composite sintered body for a composite wire drawing die.

A polycrystalline diamond wire drawing die structure is specified in Strong, US Pat. No. 3,407,445.

Incidentally, a single crystal diamond die is suitable for drawing thin tungsten wire. However, as wire diameters exceed about 0.008 inches (0.203 mm), single-crystal diamond dies become large, expensive, and breakable. Therefore, metal-bonded carbide dies are commonly used to draw tungsten wire of diameters greater than 0.010 inches (0.254 mm), despite their relatively short service life.

Commonly used diamond wire drawing die assemblies consist of natural single crystal diamond supported in a specialized sintered metal matrix. In order to achieve the support of single crystal diamond dice,
The diamond may be placed within the mounting ring, the space between the diamond and the ring may be filled with sinterable metal, and the metal may then be sintered. Sinterable metals useful for such purposes must not violate the diamond during the sintering operation. Following such criteria automatically excludes the use of metals with high yield strength and high modulus of elasticity. This is because such metals are strong carbide formers by their nature and will of course attack the carbon source (ie the diamond in contact with the metal) under the high temperatures required for sintering.

As a result, due to the inherent properties of sinterable support metals (i.e. low yield strength and low elastic modulus),
A large (approx.
Application of compressive stress (greater than 10,000 psi (7 Kg/mm ² )) is prohibited. Conventional sintered metal-supported diamond dies can be pre-stressed to approximately 10,000 psi at room temperature. However, when the wire drawing operation is performed hot, such compressive stress decreases rapidly as the operating temperature of the die increases.

Diamond is weak in tension. It would therefore be particularly advantageous if such drawbacks could be compensated for by permanently applying compressive stress of about 10,000 psi or more to the outer surface of the diamond.

Polycrystalline diamond wire drawing dies, such as those described in US Pat. No. 2,407,445, also present the same problems as far as die mounting is concerned. Alternatively to the use of a sintered metal matrix, such dies may be press-fitted into a binding ring, but the irregular outer surface of the die (as fabricated) may be ground to a shape suitable for press-fitting. Cost is an economic hindrance.

Therefore, an improved wire drawing die structure, especially one for drawing wire at high temperatures from strong, hard metals such as tungsten, molybdenum, and steel, would provide many benefits to the industry. It will be.

The present invention provides such an improved wire drawing die structure. According to the simplest embodiment, the composite die structure of the present invention comprises a core made of polycrystalline diamond and having a through hole in the center which serves as a shape and dimension determining element of the line, and an outer body made of metal-bonded carbide. Consists of a covering. The metal-bonded carbide is directly bonded to the core to strengthen it, and is also easy to form into a rotating body. (For drawing wires with a diameter of 0.008 inch or more)
According to a preferred embodiment, a composite die structure is used in which at least one high-strength metal ring is press-fit around a composite structure consisting of a polycrystalline diamond core inside a metal-bonded carbide jacket. be done. Following such an arrangement, the external rotating surfaces of the composite structure are permanently placed under high compressive stress (greater than about 10,000 psi).

The invention, as well as its objects and advantages, will be better understood from the following description taken in conjunction with the accompanying drawings.

The tendency of diamond dies in use to crack before they reach the stage of wear that requires replacement, especially those that are thick (0.013 inch (0.33 mm) or larger).
Such tendencies in drawing lines have been known for a long time. It has already been recognized that this type of failure is due to the lack of sufficient support for the tensile weak diamond. However, the choice of supporting metal matrix is limited by the above criteria and, as a result,
In particular, no structure has yet been devised that can apply large compressive stress to the outer surface of single crystal diamond during hot working.

The present invention provides a novel method for manufacturing sintered compacts for wire drawing dies by utilizing ultra-high temperature and high pressure technology. That is, the present invention provides (a) an outer block consisting of a powder for forming a sintered metal-bonded carbide alloy or a sintered metal-carbide alloy body and having a cavity formed therein; (b) placing the loading assembly and its contents into a mass of about 1,300 to
an inner mass consisting essentially of polycrystalline diamond and surrounding the inner mass and characterized in that it is exposed to a temperature of 1600°C and a pressure of about 50 kbar or more; (c) then cooled and the pressure removed; and an external block of sintered carbide alloy supporting under compression a composite sintered body for a wire drawing die.

The composite sintered body thus obtained consists of a strong polycrystalline diamond inner block constituting the die core and an outer sintered metal carbide (a "sintered carbide alloy" or It has a lump (shell) (also called "cemented carbide"), making it an ideal material for wire drawing dies.

First, in FIG. 1, a preferred structure for composite 10 is shown. The generally cylindrical die core 11 has a through hole 12 of suitable size and shape.
The core body 11 is a polycrystalline diamond block.
Mantle 13 is a mass of metal-bonded carbide bonded directly to die core 11 along a void-free interface. The above interface is irregular and 1 to 100
Interlocking occurs on a micron scale, and such interlocking occurs between individual abrasive grains and portions of the metal-bonded carbide mass.

Next, another structure is shown in FIG. The composite 20 in this case initially consists of a polycrystalline inner abrasive layer 21 surrounded on the top, bottom and sides, respectively, by metal-bonded carbide masses 22a, 22b and 22c. In the illustrated completed complex, masses 22a, 22b and 2
2c is integral. In either construction, the composite is shaped as a body of revolution (preferably with a taper of 2-4 degrees). In this way, the throat of the hole 23 is made of a strong, wear-resistant material.

Preferred high temperature and high pressure apparatus implementations for producing composites 10 and 20 include Hall
The subject matter of U.S. Pat. No. 2,941,248 is briefly illustrated in FIG. Also shown in FIG. 4 is a loading assembly useful in practicing the present invention.

The apparatus 30 includes a pair of sintered tungsten carbide punches 31 and 31' and an intermediate belt or die member 32 of the same material. Die member 32 has an aperture 33 within which is located a reaction vessel 34 shaped to accommodate a loading assembly as described below. Between the punch 31 and the die member 32 and between the punch 31' and the die member 3
2 and a gasket-insulator assembly 35.
, each of which includes a pair of thermally insulating and non-conductive pyrofluorite members 36 and 37.
and an intermediate metal gasket 38.

In the preferred embodiment, reaction vessel 34 includes a hollow salt cylinder 39 . However, (a) it does not convert to a stronger and more rigid state (e.g., by phase transition or densification) during high-temperature and high-pressure operations, and (b) it The cylinder 39 may be made of other materials (eg, talc) as long as they do not substantially cause volume discontinuities under high temperature and high pressure conditions.

An electric resistance heating tube 40 made of graphite is installed concentrically adjacent to the interior of the cylinder 39 . Inside the graphite heating tube 40, a cylindrical salt liner 41 is also installed in a circular manner. liner 41
Salt plugs 42 and 4 are installed at the upper and lower ends of the
2' are fitted into each.

At both ends of the cylinder 39 are end disks 4 made of conductive metal.
3 and 43' are installed, thereby achieving electrical connection to the graphite heating tube 40. Adjacent to the end discs 43 and 43' are end cap assemblies 44 and 44', respectively, each of which includes a pyrofluorite plug or disc 45 surrounded by a conductive ring 46.
It consists of

Operating techniques for simultaneously applying high temperatures and pressures in such devices are known to those skilled in the art.
Note that the above description is only about one example of a high temperature and high pressure device. That is, various other devices can be used within the scope of the present invention as long as they can generate the required temperatures and pressures.

Although not shown to scale, the third
A loading assembly 50 fits within the space 51 of the illustrated device. Loading assembly 50 consists of a cylindrical sleeve 52 made of a shielded metal selected from zirconium, titanium, tantalum, tungsten and molybdenum. Shielding metal sleeve 52
A subassembly is located within the subassembly surrounded by a shielding metal disk 54 and a shielding metal cup 56. In the case of the arrangement shown, which is intended to produce composites with straight through holes in a polycrystalline core, a wire of suitable size (e.g., 0.010 inch (0.254 mm) diameter tungsten wire) 57 is used. Suitably positioned and then bonded (eg, by welding) to the bottom of the cup 56. line 5
Hard abrasive grains 58 are arranged around the 7, thereby forming a sleeve 59 of cold-pressed sinterable carbide molding powder (a mixture of carbide powder and a suitable metal binder). vacancies are filled. If desired, sleeve 59 may be comprised of presintered metal-bonded carbide, as described below.

A particularly preferred metal to use for forming through holes in a polycrystalline core is tungsten. This is because tungsten has a high melting point and is a strong metal that can withstand deformation caused by abrasive grains even during the compression sintering process used under high temperature and pressure. Tungsten is also less difficult to remove later by melting or grinding. It should be noted that other materials such as molybdenum, zirconium, titanium, tantalum, rubidium, rhodium, rhenium, osmium and non-metals such as refractory carbides or even refractory oxides can be used. Such lines need not have a uniform cross-section as shown, but any shape that minimizes the effort required to form the preformed hole into the desired double taper configuration may be used. It is possible.

The remaining volume within the loading assembly 50 is the cylinder 3
It is occupied by disks 61a and 61b made of the same material as 9 (e.g. sodium chloride) and disks 62a and 62b made of hexagonal boron nitride. Disks 62a and 62b are configured to minimize the ingress of undesirable materials into the subassembly surrounded by disk 54 and cup 56. In addition, the sleeve 52 and the disc 5
4 and cup 56 are comprised of zirconium or titanium, the presence of these materials has been found to enhance sintering of the abrasive grains and bonding of the metal bonded carbide jacket thereto.

In the method of the present invention, the above-mentioned loading assembly is carried out under high temperature and high pressure (approximately 1300 to 1600°C, approximately 50 kilobar or more) using, for example, the above-mentioned high temperature and high pressure equipment.
It is then subjected to a compression sintering process. As a result, the diamond particles aggregate to form a strong polycrystalline inner mass (core), and the outer sintered metal-bonded carbide mass (shell) surrounds and protects the inner mass. A composite sintered body is obtained that supports under compression. If additional compressive support is desired, a tie ring can be press fit onto the outside of the composite.

Example 1 From cold pressed grade 55A carboloy powder (13 (wt)% Co + 87 (wt)% WC), dia.
A sleeve 59 was made with a 0.101 inch perforation. This sleeve was placed inside a zirconium cup. In the center of the interior of the cup, as shown in Figure 4, stood an upright 0.010 inch diameter tungsten wire welded to the bottom. 100-200 meshes of diamond grains were injected around the tungsten wire, thereby filling the perforations in the sinterable sleeve. Note that the sleeve 52 and the discs 54, 63a and 63b were also made using metallic zirconium (0.002 inch (0.051 mm) thick). Such a loading assembly was introduced into a high temperature, high pressure apparatus such as that shown in FIG. After applying a temperature of 1500° C. and a pressure of about 55 kbar for about 60 minutes, the temperature was allowed to drop to near room temperature and then the pressure was released.
The diamond-metal bonded carbide composite recovered from the device had a diameter of about 0.23 inches (5.8 mm) and a length of about 0.22 inches (5.6 mm). The tungsten wire, zirconium envelope and part of the metal-bonded carbide exterior were melted in a hot HF+HNO ₃ bath. A protective fused polyethylene coating was then applied to the surface of the composite while the tungsten wire was completely removed by continuing the erosion operation.

In structures where diamond grains are used as the mass 58, extremely extensive diamond-to-diamond bonding is achieved. The preferred particle size for the diamond crystal particles used in the charge is 230-270 mesh (US standard sieve), although other particle sizes can of course be used. That is, the diamond grain size can range from about 0.1 to about 500 microns.

If diamond grains are used as the die core, the preferred initial diamond content is 100% (by volume). After fabrication, the composition of the die center body is 90~
98 (volume)% diamond and 2-10 (volume)
% metal binder (also used for metal binding carbides). In any case, at least 70% (by volume) of diamond must be present in the finished die core to ensure diamond-to-diamond bonding. If the initial diamond content is 70-90% (by volume), sinterable carbide powder or metal powder can be mixed with the diamond.

In making a composite die with a diamond core, the loading assembly 50 is placed in the apparatus 30, pressure is applied, and the system is heated. In this case, temperatures in the range of about 1300-1600°C are used for about 3 minutes or more to sinter the carbide-metal binder mixture, while at the same time providing thermodynamics to the diamond in the system. High pressures, for example of the order of 55 kbar, are applied to the system to ensure stable conditions. At 1300°C, a minimum pressure of approximately 50 kilobar is required, and at 1400°C, a minimum pressure of approximately 52.5 kilobar is required. Under the operating temperature, of course, the metal binder in the system will melt, so that some of it will migrate from the mass 59 into the mass 58. Such a metal binder could serve as a catalyst and solvent for the growth of diamond crystals, especially in the case of making polycrystalline diamond cores.

No special bonding layer is required between the extremely high-strength, wear-resistant core and the surrounding rigid carbide support.

If a carbonized powder is used, it is preferably a commercially available tungsten carbide shaped powder (a mixture of tungsten carbide powder and cobalt powder) with a particle size of 1 to 5 microns. If desired, all or part of the tungsten carbide can be replaced with titanium carbide,
It can also be replaced with one or more of tantalum carbide, molybdenum carbide, chromium carbide, vanadium carbide, and the like. Small amounts of other carbide powders can also be used to ensure outstanding properties of the composite. Considering that nickel and iron have also been used in some cases as binders for carbides;
The material providing the metallic bond in the sintered compound can be a member selected from cobalt, nickel, iron and mixtures thereof. However, cobalt is preferred as the metal binder. The composition of the carbide molding powder useful in the practice of this invention is about 75-94
(by weight)% carbide and about 6-25% (by weight) metal binder. Examples of such carbide molding powders include grade 883 Carboloy (6% Co + 94% WC by weight) and grade 55A Carboloy (13% Co + 87% WC by weight). For example, a pre-sintered carbide sleeve (FIG. 1) or disc (FIG. 2) may be produced by the use of the powders described above, in which case such sintered shapes are Used in place of inter-pressed molded products.

The composite die of the present invention can, of course, be made without a through hole, with a straight through hole, or with a double tapered through hole. However, in either case some shaping is necessary to give the correct dimensions. If the composite die has a built-in hole in its core, it is only necessary to pull out the wire soaked with fine diamond powder, making it easier to form. If desired, a laser may be used to form the initial holes in the die core. If the hole in the die core becomes enlarged due to normal wear and erosion, the hole can be reshaped for drawing thicker wire.

After a composite (e.g., composites 10 and 20) with accurately sized through-holes is fabricated, one of the main advantages of such structures is that the outer surface of the composite is shaped like a body of revolution (e.g., a regular cylinder or a truncated cone). ) is precisely formed. When properly shaped to have substantially the same center as the through-hole in the die core, such composites can be housed within one or more high-strength tie rings, thereby providing ^a
The above compressive stress can be applied uniformly.
With proper design and construction, such compressive stress will be permanently and uniformly transmitted through the composite to the outer surface of the die core.

The tie ring may be made of any suitable material of high strength (under working conditions) such as superalloys, stainless steels, high strength steels, dispersion hardened alloys, reinforced metals, reinforced plastics, and cemented carbides.

In the assembly shown in FIG. 5, the sintered carbide jacket of composite 70 was precisely shaped as a regular cylinder. Such a composite 70 (e.g.
0.3020 inch (7.671 mm)) is press fit into metal ring 71 (e.g., 0.3017 inch (7.663 mm) inner diameter) and then has a tapered inner surface to match the tapered outer surface (preferably 2-4%) of metal ring 71. The composite 70 and metal ring 71 subassembly was press fit into a metal ring 72 having a . The die assembly can also be housed within a security ring 73 in case of rupture.

For a die assembly for drawing tungsten wire, for example, ring 71 is made of H-21 steel, ring 72 is made of superalloy (René 41), and ring 7
3 is made of stainless steel. Also, in the case of a die assembly for drawing soft metal wire (eg copper wire) at low temperatures, all rings may be made of stainless steel.

The die assembly shown in FIG. 6 is easier to assemble and requires fewer parts.
In this example, the outer surface of the cemented carbide jacket of composite 80 was precision ground as a truncated cone with an approximately 2-4% taper. The tapered composite was press fit into ring 81. Fifth
As in the case shown in the figure, a ring 82 is installed for security, but it is the ring 81 that applies compressive stress.
It is.

It is also possible to create a die assembly in which a cylindrical composite is shrink-fitted into a tie ring. Such an assembly is useful, for example, for low temperature (about 100° C. or less) wire drawing of copper. Such assemblies are severely limited in terms of the amount of compressive stress that can be applied to the composite die.

Of course, the through holes in the die core need not be circular.

Example 2 Cold pressed powder (87 (wt)% WC+13
(by weight)% Co) was made into a thick-walled sleeve having a length of about 0.15 inches (3.8 mm), an inner diameter of about 0.10 inches (2.5 mm), and an outer diameter of 0.25 inches (6.4 mm). The sleeve was placed inside a tightly sized zirconium cup approximately 0.002 inches (0.051 mm) thick. The central perforation was then filled by injecting 230/270 mesh synthetic diamond grains and lightly compacting them. Two zirconium disks, each approximately 0.25 inches in diameter and 0.002 inches thick, were then placed on top of the diamond-filled sleeve. The entire zirconium cup and pressed powder sleeve was contained within a 0.001 inch (0.026 mm) walled zirconium tube. The assembly was placed in a compressed salt holder and then inserted into a graphite heating tube as described in connection with FIG. Approximately 55% pressure on the assembly
After raising the temperature to kilobar, heating was carried out at approximately 1550°C for 60 minutes. After cooling and subsequent pressure relief, the entire cup, sleeve and diamond were recovered as a solid cylinder. After dissolving the deposited zirconium in a HF-HNO ₃ mixture, the end face of the central diamond pillar was inspected by polishing one end face of the cylinder on a diamond lap. As a result, extensive diamond-diamond bonding was observed. Next, the side surface of the cylinder (metallic bonded carbide) has a diameter of 0.204
Ground to inches (5.182mm). On the other hand, 0.2024
inch (5.141mm) inner diameter, 1.50 inch (38.1mm)
A mild steel ring with an outside diameter of 0.50 inch (12.7 mm) and a thickness of 0.50 inches (12.7 mm) was made and then heated to 400°C. The diamond-containing cylinder described above was quickly pressed into the hole of the ring, and then the whole was allowed to cool. Finally, a 0.015 inch (0.381 mm) diameter hole suitable for drawing the tungsten wire was formed in the diamond pillar. Tungsten wire was drawn using the thus completed die assembly. For line drawing work, the number of dies is approximately 400.
The wire was preheated to approximately 800°C while the wire was maintained at 800°C.

After drawing approximately 54 kilograms of tungsten wire, the dimensions and shape of the resulting wire indicated that the diamond section had fractured due to the bursting force exerted by the wire passing through the die. Apparently, the radial compressive support provided by the mild steel ring was insufficient under such operating conditions. However, the life of the die described above was comparable to that exhibited by natural single crystal diamond dice for such conditions.

Example 3 A diamond grain and WC+Co sleeve assembly similar to that described in Example 2 was made. However, the perforations in the sleeve in this example had a diameter of 0.125 inches (3.18 mm). As in Example 2, after encapsulating such an assembly in zirconium and subjecting it to high temperature and pressure, the cylinder was recovered and had an outside diameter of 0.204 inch (5.18 mm).
was ground and then pressed into a mild steel ring similar to that in Example 2.

A diameter of 0.0128 inches (0.325
A wire drawing die for drawing tungsten wire (mm) was fabricated. Such a die was used under similar conditions as in Example 2.

After drawing approximately 700 kilograms of tungsten wire, the cylinder inside the ring became loose and the die was taken out of service for inspection. As a result, it was found that although the die was not cracked or significantly worn, it was found to be unusable due to loosening within the binding ring. Still, the die exhibited more than twice the lifespan of traditional single-crystal diamond dies. The die was then reinstalled in a ring that provided greater compressive stress and re-drilled to draw a thicker wire;
Even after that, satisfactory performance was obtained.

Example 4 As in Example 3, a composite die body consisting of polycrystalline diamond and a sintered tungsten carbide-cobalt sleeve was fabricated and the outer diameter
Ground to 0.204" (5.182mm). The body was pressed into a hardened abrasive sleeve made of hot worked tungsten steel. The sleeve had an inside diameter of 0.2037 inches (5.174 mm) and a length of 0.250 inches (6.35 mm), and its outer surface was tapered (0.450 inches (11.4 mm) in diameter at one end and 0.25 inches (11.4 mm) in diameter at the other end). 0.445 inch (11.3mm)). Such an assembly then has a thickness of 0.50 inches (12.7 mm) and an outside diameter of 1.50 inches (38.1 mm) (18-8 stainless steel security ring wall thickness of 0.062 inches (1.55 mm)).
) with approximately 3000 pounds (1360 Kg) of force into the tapered hole of a Rene 41 ring.
As a result, the René 41 ring exerts approximately 120,000 psi (84 Kg/mm ² ) of compressive stress on the internal assembly.
This prevented the bursting force exerted by the wire passing through the die. The completed assembly is similar to that shown in FIG.

A die suitable for drawing 0.013 inch (0.33 mm) diameter tungsten wire was prepared by drilling and finishing the diamond core according to traditional techniques. After several months of use, over 1100 kilograms of high-temperature tungsten wire was drawn from the die during normal production. However, the die still looked like new and continued to be used. To this point, the dies described above have produced several times the amount of tungsten wire compared to the best traditional diamond dies used under the same operating conditions.

Example 5 Sintered tungsten carbide-cobalt (87% (by weight) WC + 13% (by weight)
Co) diameter 0.170 inch (4.32 mm) in the center of the cylinder
hole was formed. The hole was filled with 230/270 mesh synthetic diamond grains. The resulting assembly was surrounded by a 0.002 inch thick zirconium plate and then placed in a high temperature, high pressure reaction vessel as described above. A pressure of approximately 55 kbar is applied to the loading assembly, while approximately
Heating was carried out at 1550°C for 58 minutes. After cooling, the pressure was released and the loading assembly was recovered as a solid cylinder. The outer zirconium layer was removed with an abrasive and then both end faces of the cylinder were polished on a diamond lap. After the ends of the diamond core were flattened, a microscopic examination was performed. As a result, it was found that the diamond core was composed of a large number of crystal grains tightly bonded to each other, and many diamond-diamond bonds were observed. The length of the cylinder was 0.205 inches (5.21 mm). Next, the side of the cylinder is 2%
The large end face had a diameter of 0.329 inches (8.36 mm) and the small end face had a diameter of 0.325 inches (8.26 mm).

A ring having a thickness of 0.37 inches (9.53 mm) and an outside diameter of 1.00 inches (25.4 mm) was made from 18-8 stainless steel. The internal bore has a 2% taper and the diameter at the larger end is
It was 0.3266 inch (8.296 mm). The diamond-sintered carbide composite cylinder described above was pressed into the hole with a force of approximately 500 pounds (227 kg), resulting in an assembly similar to that shown in FIG. 6, with the exception of the security ring. Ta. In this way, 18
-8 Stainless steel ring is attached to the inner composite cylinder with approx.
It will exert a hoop compressive stress of 40,000 psi (28 Kg/mm ² ).

A die for drawing 0.403 inch (10.23 mm) diameter copper wire was made by drilling and finishing the diamond core in such an assembly according to traditional techniques. After several months of use, these 50,000 lb (23 t) dies exhibited excellent surface finish suitable for enamel insulation.
copper wire was produced. Moreover, the polycrystalline friction surface also appeared to improve the lubrication of the passing wire by trapping lubricant from the lead-in wire. This die assembly continued to be used.

A composite sintered body having an inner block of polycrystalline diamond and an outer block of sintered carbide alloy surrounding it obtained by the method of the present invention does not require press fitting of a binding ring (high-strength metal ring). However, the effect that a compressive force is applied from the external block to the internal block (the internal block is reinforced and supported) has already been achieved. Of course, depending on the application, it may be preferable to apply additional compressive force by press-fitting the binding ring. For example, the above-mentioned Examples 1 to 4 all show that the composite is further pressed into a steel ring as a preferred embodiment to demonstrate the effectiveness of the present invention under harsh conditions (particularly large amounts of thick tungsten wire being drawn). This is an example in which additional compressive force is applied by press-fitting.In the method of the present invention, the metal carbide alloy used to form the outer lump is the polycrystalline alloy that forms the inner lump. The coefficient of thermal expansion is larger than that of diamond, and therefore, when the sintered carbide alloy is cooled and the pressure is removed after applying high temperature and pressure, the outer lump of the sintered carbide alloy undergoes a relatively larger contraction than the inner diamond lump. As a result of the external mass applying compressive support force radially inward to the internal mass, the internal mass (diamond core) serving as a wire drawing die is sufficiently reinforced. This is the most important feature, action, and action of the method of the present invention.
It's an effect. However, as mentioned above, when manufacturing a die, it is not necessarily necessary to further press-fit the thus obtained composite into a binding ring, and in fact, in many die applications, it is not necessary to further press-fit the composite body obtained by the method of the present invention. The assembled composite is simply inserted into a frame made of brass or other hard metal material (not a press fit).
Therefore, no additional compressive force is applied to the composite) and it can be used by being incorporated into a wire drawing machine. However, when drawing materials such as tungsten, which are particularly thick and difficult to work with, it is preferable to press-fit the composite into the binding ring to support the additional compressive forces; The provision of is a known technique per se, and does not constitute a new and unique requirement of the present invention.

An example of the present invention in which press fitting is not performed is shown below.

Example 6 A diamond grain and WC+Co sleeve assembly similar to that described in Example 2 was made. However, the perforations in the sleeve in this example had a diameter of 0.125 inches (3.18 mm). As in Example 2, after encapsulating such an assembly in zirconium and subjecting it to high temperature and pressure, the cylinder was recovered and had an outside diameter of 0.204 inch (5.18 mm).
Grinded to . It was then held in the steel sleeve using a hollow threaded plug without being press fit into the steel ring. By drilling a hole in the diamond mass column according to conventional drilling techniques,
A wire drawing die for drawing 0.0128 inch (0.325 mm) diameter tungsten wire was manufactured. This die showed superior performance to conventional wire drawing dies made from sintered carbide alloys, and exhibited more uniform and lower wear rates than conventional wire drawing dies made using perforated single crystal diamond.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a composite wire drawing die consisting of a generally cylindrical polycrystalline core with a double-tapered through hole and a metal-bonded carbide jacket directly bonded thereto; FIG. The top, bottom, and sides of the layer are surrounded by an integral metal-bonded carbide layer directly bonded thereto and span at least the throat of a double-tapered through hole to aid in line shape and sizing. A cross-sectional view of a rotating body-shaped composite die defined by a polycrystalline layer; FIG. 3 is a cross-sectional view (partially an elevational view) showing an example of the high-temperature and high-pressure apparatus for manufacturing the composite die of the present invention; , FIG. 4 is a cross-sectional view of a loading assembly to be introduced into the working space of the apparatus of FIG. 3, and FIGS. 5 and 6 are cross-sectional views of an embodiment of a composite die-tying ring assembly. In the figure, 11 is a polycrystalline core, 12 is a through hole, 1
3 is a metal-bonded carbide jacket, 21 is a polycrystalline layer, 2
2a to 22c represent metal-bonded carbide layers, and 23 represents a through hole.

Claims (1)

[Claims] 1 (a) An outer block consisting of a powder for forming a sintered metal-bonded carbide alloy or a sintered metal-carbide alloy body with a cavity formed therein, and a diamond crystal grain in the cavity of the outer block. (b) subjecting the loading assembly and its contents to a temperature of about 1300-1600°C and about 50°C;
an internal mass consisting primarily of polycrystalline diamond and a sintered mass surrounding and supporting it under compression, characterized in that it is exposed to a pressure of at least kilobar; (c) then cooled and the pressure removed; A method for manufacturing a composite sintered body for a wire drawing die having an outer mass of a cemented carbide alloy.