SE1350476A1 - Mixing ceramic cutting tool and mixing of ceramic granules therefor and method of making the cutting tool - Google Patents

Abstract

Summary A mixed ceramic jointing tool, in particular a cutter or a water vessel having at least two ceramic hard materials. A first hard material then shows an oxide of zirconium or molybdenum or flab, and the second hard material has a carbide or a nitride of a compound of at least two of tantalum, tungsten, hafnium or rhenium.

Description

The invention relates to a mixed ceramic splicing tool according to the preamble of claim 1, a mixture of ceramic granules for sintering such a splicing tool according to the preamble of claim 5 and a process for producing of a mixed ceramic splicing tool according to the preamble of claim 7.

Kanda ceramic splicing tools, for example of cubic crystalline boron nitride (CBN), or of an oxide ceramic such as Al2 O3, have a high hardness, temperature resistance, heat resistance and wear resistance and chemical resistance. With them, high turning or processing speeds are achievable in intermittent machining. For this purpose, lubricant / coolant-free dry processing can take place with them, since a reduction of the thermal load of an edge in engagement due to their high-temperature half-strength is not necessary.

However, these favorable properties of the said ceramics are in contrast to their unfavorable sprocia material behavior.

Due to toughness on toughness and buoyancy strength, ceramic shear materials are nowadays still insufficient when used at high feed speeds or in intermittent turning such as occurs during milling. these the hardness and heat resistance as ceramic materials or hard materials. 1 When using mixtures of ceramics, in particular on the basis of oxide and nitride ceramics such as Al2O3 and Si3N4, it provides cutting materials with high hardness and a better yield strength.

The disadvantage of these mixtures is, however, that the use for the cutting material alarmed is relatively small in the area of higher speeds or in intermittent turning, since these mixing ceramics still have a relatively low toughness. In addition, a loss of hardness is obtained compared with the hardest oxide ceramics or CBN.

There are also known mixing ceramics based on alumina (Al2 O3), titanium carbide (TiC) and titanium nitride (TiN). However, these have only limited possibilities of use in the hard finishing during continuous cutting or for finishing cast iron in slat or in intermittent turning. In contrast, the invention is based on the task of creating a universally usable mixed ceramic jointing tool and a mixture of ceramic granules and a manufacturing method thereof.

This object is achieved with a splicing tool having the sardragen according to claim 1, a mixture of ceramic granules with the sardragen according to claim 5 and a manufacturing process having the sardragen according to claim 7.

Advantageous developments of the invention are described in claims 2 to 4, 6 and 8 to 25.

A mixed ceramic jointing tool especially after a cutter or a water vessel has at least two ceramic hard materials. According to the invention, a first hard ceramic material is an oxide of zirconium or molybdenum or niobium and a second ceramic head material comprises a carbide or a nitride formed of a compound having at least two of the following materials: tantalum, tungsten, hafnium, rhenium. 2 The oxide of zirconium or molybdenum or niobium thus has a dispersing effect on the mixture of the ceramic hard materials and gives the cutting tool a rigid toughness.

Preferably, the first hard ceramic material exhibits Zr0 or ZrO2 or MoO2 or NbO2. The carbide or nitride with the at least two substances gives the cutting tool its high hardness.

Thus, the use of two different materials in the carbide or nitride helps to form a bridge with the oxide of the first hard ceramic material, and also increases the hardness of the cutting tool compared to conventional splicing tools. The second hard material preferably comprises tantalum with tungsten or with hafnium or with rhenium, or voifram with hafnium or with rhenium, or hafnium with rhenium. Preferably especially Tantalum hafnium carbide (Ta4HfC5), Tantalum rhenium carbide, Tungsten tantalum carbide or Tungsten niobium carbide.

Due to the increased hardness and increased toughness due to the selected hard material mixture according to the invention, the cutting tool can be used in a more flexible and universal way. [Armed Jr it particularly suitable for drilling, turning or milling. The field of application extends beyond areas of materials with different material properties and spawning properties, such as ferritic materials, automatic steels, construction steels, hardened steels, superalloys, cast iron and ADI cast iron. In addition, the range of different types of machining such as precision machining, medium machining, hard machining and surface treatment and grinding are possible.

This enables hard machining with geometrically defined cutting edge for all machining processes, even with intermittent turning and workpieces with different 3 hardness zones. Compared with conventional ceramic cutting tools, the life of the cutting tool is increased about twice and the cutting life is approximately 54 times due to the very wear-resistant hard material.

Another advantage is the increased process security, as a tool failure will or does not occur. Thus, committee and machine damage are also reduced. The splicing tool according to the invention also allows a cutting speed of about 2.5 times compared to conventional ceramic splicing tools.

A special advantage of the universal splitting tool is that it can replace several special tools, which can reduce logistics, capital and operating costs in the area of Mr. splitting processing. a preferred embodiment of the splicing tool, the latter also has a third ceramic hard material comprising a carbide or a nitride different from the second ceramic hard carbide or nitride, and formed by one of the above compounds with at least two of the materials aunt! tungsten, hafnium, rhenium. By suitable selection of the third ceramic, the field of application of the ceramic splice tool can thus be focused on narrower applications or expanded further.

A preferred embodiment of the splice tool has a fourth hard ceramic material, which comprises an oxide which differs from the first hard ceramic material and which comprises zirconium or molybdenum or niobium according to the following description.

An increase in the toughness and hardness of the joint tool in comparison with conventional joint tools is obtained if a mass fraction of the first or the first and the fourth hard ceramic material amounts to about 20-40%, and a mass fraction of the second or the second and the third hard ceramic material, amounts to about 80 - 60% of the ground joint tool. Thus, preferably, the second or second and third ceramic hard materials (carbide / nitride) function as a ceramic matrix in which the first ceramic hard material is embedded, or the first and second ceramic hard materials (oxide) or are embedded. .

As a precursor for sintering a mixed ceramic joint tool according to the following description, a mixture according to the invention is preferred which has granules of a first ceramic hard material and at least granules of the second hard material. In a preferred embodiment of the mixture, this mixture further comprises a granulate of a third or third and fourth ceramic hard material according to the previous description. If the melting temperatures of the ceramic hard material differ, it is found to be advantageous for a subsequent sintering if a particle size of the granules of the hard material having the lower temperature is about 2-10 times, more preferably 3-5 times, larger the particle size of the granules of the hard material with higher melting temperature.

Thus, a sintering can be omitted. The particle size of the granules with higher melting temperature is preferably in the range of 1/100 mm. This grid is particularly suitable for mixtures in which the second hard material comprises tantalum hafnium carbide Ta4HfC5, which has one of the highest melting temperatures of 4215 ° C.

A method according to the invention for manufacturing the joint tool described above has at least one step "approaching the melting temperature of the hard materials in the ceramic mixture".

This approach enables a sintering of the above advantageous splice tools. The approach approach is to prefer an installation of different pressures for the different hard materials.

In a preferred embodiment of the process, a step "combining the granules of the mixture of hard materials, in particular through paraffin", is carried out before the step "approaching the melting temperature".

In a further preferred embodiment of the process, a step of "hot pressing of the mixture of granules and paraffin" is carried out after the step "unification of granules" and before the step "sintering".

In a further preferred embodiment of the process,% tier in connection with or during the step "approaching the melting temperature" of the ceramic hard material, the step "sintering" of the mixture of ceramic hard materials.

Embodiments of mixtures of hard materials according to the invention for a splice tool with male reference to a table and an embodiment of the splice tool according to the invention are explained in detail with male reference to Iva schematic drawings. The drawings show: Figure 1 shows a table with examples of mixtures of hard materials Mr a splicing tool; Figure 2 shows an embodiment of the joint tool in a view from above, and 3 shows the embodiment of Figure 2 in a cross section.

Figure 1 shows possible mixtures of hard materials for manufacturing or for sintering a splice tool in accordance with the invention. In Figure 1 to the left, in the table relating to the first hard material, the hard materials are indicated, which are arranged to achieve the intentional increase of toughness in the mixing frame. These are zirconia (ZrO2), molybdenum dioxide (MoO2) and niobium dioxide (NbO2).

The right table Figure 1 lists possible other hard materials, which can be formed from a combination of two materials from the amount of tantalum, hafnium, tungsten, rhenium, possibly in combination with carbon (carbide) or nitrogen (nitride). This results in a potential amount of at least six pairs of combinations, i.e. 12 different other hard materials.

Considered on this on its own, ie without the presence of the first hard material, the cutting tool of the illustrated carbides would be very hard and brittle. Its hardness on the Mohs scale would be> 5, the hardness of Tantalhafnium carbides is for example 9-10. The distinguishing properties of the material of the carbide and nitride are thus their high hardness and heat resistance, as well as their temperature resistance.

The proposed mixture of the first and second hard materials such as grains is based on a first hard material, such as zirconia over a dashed line symbolizing the mixture 20, to the selected second hard material, for example tantalum hafnium carbide. The chemical association of tantalum and hafnium with carbon to form tantalum hafnium carbide is thus symbolized according to Figure 1 above the drawn line 22 shown.

Tantalum hafnium carbide is an extremely hard, non-oxidizing ceramic, which has one of the highest melting points of 4215 ° C.

In the exemplary embodiment of the mixture of hard materials with tantalum hafnium carbide and zirconia, the tantalum hafnium carbide contributes to the extreme hardness, thermal stability and heat resistance, so that the splicing tool formed therefrom can be used especially for high speeds and hard materials. 7 Via the first hard material, for example the mixing partner of tantalum hafnium carbide, the zirconia, the proposed mixture of hard material becomes tougher. The zirconia in the mixture shows a dispersing behavior which promotes this toughness. In particular, hafnium contained in tantalum hafnium carbide thereby helps to bridge the gap between tantalum hafnium carbide and zirconia. The toughness in the mixture of hard materials introduced by said first hard material zirconia enables the use of the splicing tool at high feed speed and in particular when the intermittent turning, which is given for example during milling.

Further particularly preferred embodiments, such as those miscible according to Fig. 1, are molybdenum dioxide in combination with tungsten niobium carbide, niobium dioxide combination with tantalum tungsten carbide or mixtures formed with tantalum rhenium carbide, whereby the highest hardness can be expected. As an alternative to niobium dioxide, compounds with Nb 2 O 5 are also possible.

When using a third hard material which differs from the second hard material in accordance with the description above, this is possible via combinations shown according to Figure 1 for the second hard material.

Analogously, when using a fourth hard material which differs from the first hard material according to the foregoing description, it is possible through the above-mentioned combinations which according to Figure 1 are possible for the first hard material An embodiment of a mixed ceramic joint tool 1 designed as a notch with a chip breaker for an optimized chip departure is illustrated in Figures 2 and 3. The notch is designed in S-shape (square). The first hard material is a hard ZrO 2 and the second hard material is a hard and thermally stable tantalum hafnium carbide Ta4HfC.

The hard materials are present in a mass ratio of 40% and 60% in the cutting tool 1. The embodiment exhibits a high hardness and toughness, so that it is suitable for universal machining operations. The field of application is extended to turning, milling, drilling, surface treatment, grinding and drilling of walkways.

Machinable materials are automatic steels, structural steels, hardened steels, cast iron and superalloys. The application area extends far Over the classes according to DIN ISO 513 A cross section of the cut 2 is in this first embodiment 15 mm. Homen 4 has 10 cut rounded horns with a radius Ro of 1.6 mm. The rounded MIs 4 each have, in a plane accustomed to the viewer of Fig. 2, a peripheral cutting edge 6. To illustrate the relevant geometries of the cutting edge 1, a description of Fig. 3 now follows.

Figure 3 illustrates the first embodiment according to Figure 2 along the section A-A (see Figure 2). The insert has a tool reference plane 8, which is defined as being arranged perpendicular to the assumed cutting direction 10 of the insert (according to DIN 6851). Furthermore, a cutting point (not shown) of the cutting edge 6 is arranged in the tool reference plane 8. The cutting edge has a support surface 11 for resting on a tool holder (not shown). The support surface 11 is thus parallel to the tool reference plane 8. In a normal operation of the cutter, the workpiece is moved parallel to and opposite to the cutting direction 10 past the cutting plate 1. The cutter thus engages the workpiece with a certain engaging depth, over which the frame thickness is determined.

The cutting edge is arranged so that a slack surface 12 is parallel to an assumed working plane on the cutting plate. It follows that a slack angle ci between the assumed working plane and the slack surface 12 has a value of 0 0. Furthermore, the insert is arranged so that a wedge angle 13 between the slack surface 12 and a cutting surface 14a has a value of 90 0. This is indicated by a cutting angle y which spans between the chip surface 14 and the tool reference plane 8 has a value y which is 0 0. The slack surface 12 is delimited towards the chip surface 14 by the cutting edge 6. The cutting edge 6 has a radius R1 of 0.3 mm. Due to the above mixture of hard materials and the right angle wedge angle 13, the cutting edge 69 is protected against breakage, especially during the handling of the hard machining and / or intermittent turning.

In the direction of the san exit, which follows from the left to Niger according to Figure 2 along the left chip surface 14, adjacent to the chip surface 14 adjoins a transition surface 16 which has a transition radius R2 of 0.5 mm. This transition surface 16 is a section of a chip breaking surface. 18, which protrudes from the chip-breaking surface 14, its chip-breaking surface depth B. is broken. The chip-breaking surface 18 thus has a chip-breaking angle 6 corresponding to -37 to the tool reference plane 8. [Armed is the chip-breaking angle defined according to the previous description from the tool reference plane 8.

This steep slope of the chip breaking surface 18 towards the chip surface 14 and the tool reference plane 8 leads to an improved chip formation during the rotating machining of the workpiece. There will always be more of advantageous cylindrical or helical spiral spans. Also discontinuous spans can be observed more and more. The formation of bands and / or random spans is reduced compared with conventional shapes of cutters, especially T-beveled cutters.

Described is a mixed ceramic jointing tool, in particular a cutter or a water vessel having at least two ceramic hard materials. A first of the hard materials is an oxide of zirconium or niobium or molybdenum, and the second of the hard materials comprises a carbide or a nitride of a compound of at least two of tantalum, tungsten, hafnium or rhenium.

Reference slippage 1mixed ceramic jointing tool 2transection 4Morn 6carving edge 8Werkzeugbezugsebene cutting direction 11stOd surface 12lap surface 14span surface 16over transition surface 18span-breaking surface L-span depth span-breaking surface depth slack angle wedge angle 7span angle 6; 6 'span breaking angle 11

Claims (1)

A blend ceramic jointing tool with at least two ceramic hard materials, characterized in that a first of said ceramic hard materials comprises an oxide of zirconium or molybdenum or niobium, and that a second of said ceramic hard materials comprises a carbide or a nitride of a compound of at least two of tantalum, tungsten, hafnium, rhenium. A splicing tool according to claim 1 with a third ceramic hard material comprising a carbide or nitride different from the second ceramic hard material, and comprising a compound of at least two of tantalum, tungsten, hafnium, rhenium. A splicing tool according to claim 1 or 2 comprising a fourth ceramic hard material comprising an oxide different from the first ceramic hard material, and comprising zirconium or molybdenum or niobium. A splicing tool according to any one of claims 1 to 3, wherein a mass fraction of the first or the first and the fourth hard ceramic material amounts to 20-40% of the mass of the splicing tool, and a mass fraction of the second or the second and the third hard ceramic the material amounts to 80-60% of the mass of the joint tool (1). Mixture of ceramic granules for sintering a joint tool (1), characterized in that it comprises at least a first and a second hard ceramic material according to one of the preceding claims. A mixture according to claim 5, wherein a particle size of granular of the hard material having the lower melting temperature is about 2 to 10 times larger than a particle size of granular of the hard material having the higher narrowing temperature. A process for the manufacture, in particular sintering, of a mixed ceramic splicing tool (1) according to any one of claims 1 to 4, and consequently comprising At least after the first and a second kind of material may be characterized by a step: . " A method according to claim 7, wherein the step "approaching the melting temperatures" is performed by a step "adjusting different pressures Mr the different hard materials". A method according to claim 7 or 8, wherein before the step "approaching the melting temperatures" a step is performed "combining granules of hArt material" Separately with a paraffin. The method of claim 9, wherein following the step of "cleaning the granules" follows a step of "hot pressing the mixture of granules and paraffin" and following the step of "sintering". 13 1/2 Tantalum tungsten -Carbide -Nitride 22 2. Hard matter Tantalhafnium Tantalrhenium Wolframhafnium Wolframrhenium Hafniumrhenium Resin Zirconia Zr02 Molybdenum dioxide Mo02 Niobium dioxide Nb02