DE102019207962B4 - Tooth for attaching to an excavator bucket - Google Patents

Abstract

Tooth (20) for attachment to an excavator bucket (12) of a bucket-wheel excavator, the tooth (20) being formed in part from a metal matrix composite material and the metal matrix composite material having an insert (44) made of a hard material cast in a metal matrix material (42). , wherein the insert (44) at least partially forms the surface of the tooth (20), characterized in that the insert (44) made of the metal matrix composite material is arranged at least in the area of the tooth head (22) and this tooth head (22) in the area at least two outer surfaces (26, 30) and that the insert (44) has a larger proportion of hard material in the area of the tip of the tooth tip (22) than in other areas of the tooth tip (22).

Description

The present invention relates to a tooth for attachment to an excavator shovel of a bucket-wheel excavator, the tooth being formed in part from a metal matrix composite material and the metal matrix composite material having an insert made of a hard material cast in a metal matrix material, the insert at least partially covering the surface of the tooth forms, and a method for producing such a tooth.

Digging machines, such as excavators, in particular bucket-wheel excavators, are used to loosen hard materials such as rock in an open-cast mine. Such bucket wheel excavators have teeth, in particular digging or cutting teeth, which are attached to the bucket. Machining hard materials often causes significant wear of excavator bucket teeth, especially the tooth tips. There is therefore a need to frequently replace such teeth, resulting in high downtime and maintenance costs.

The excavator teeth are among the most common wear parts on bucket wheel excavators used to extract abrasive mineral materials. In order to reduce the frequency of tooth changes and thus increase the availability of the excavator, excavator teeth with special wear protection are used in wear-intensive excavation areas. According to the state of the art, carbide-containing layers are often applied to the surface of tooth tips using a welding electrode, which coat the tooth tip from all sides approximately evenly. Encasing quite complex tooth tip shapes with a weld coating is extremely time consuming and expensive, resulting in a multiple increase in the cost of manufacturing the bucket teeth.

From the DE 20 2015 006 273 U1 a tooth for attachment to a bucket of a bucket wheel excavator is known. The teeth of a bucket wheel excavator are usually cast from steel and provided with wear protection. This wear protection is often very brittle and cannot withstand the high loads of an excavation process. The result is rapid wear and even destruction of the excavator tooth. From the WO 2017/ 142 739 A1 teeth for excavators with local reinforcements by inserts made of hard materials are known. These inserts can extend in the rear area of the tooth in the form of a rod over its entire height extent or can be provided in a flat configuration at the tip of the head of the tooth, where they form partial areas of the underside as well as the cutting edge of the tooth. The KR 10 2018 0 055 355 A relates to a bucket part for construction machinery coupled to a bucket of the construction machinery, having a body and an enclosed wear-resistant tip.

Proceeding from this, it is the object of the present invention to provide a tooth for a bucket-wheel excavator which is easy to produce and has high wear resistance.

This object is solved by a tooth having the features of independent device claim 1 . Advantageous developments result from the dependent claims.

According to the invention, it is provided that the insert made of the metal matrix composite material is arranged at least in the area of the tooth head of the excavator tooth and encloses this tooth head in the area of at least two outer surfaces. In particular, these outer surfaces can comprise two lateral cutting surfaces and optionally a lower cutting surface of the tooth, which is also referred to herein as the central ripping surface. For example, three or more outer surfaces of the tooth head can be surrounded by the insert.

A special feature of the continuously working bucket wheel excavator is the essentially repetitive digging process with roughly the same material cross-sections, cutting speeds and tooth settings. When designed correctly, each excavator tooth is essentially stressed by a specific direction of movement (digging direction) and wears accordingly. The shape of the tooth tip changes as a result of tooth wear, which can lead to a strong rounding of the tooth tips in the area of the cutting edges and thus to a significant increase in digging force. In order to prevent the negative effect of continuously wearing excavator teeth on the excavating process, the following geometric features of the insert cast into the excavator tooth, which are preferred within the scope of embodiment variants of the present invention, are particularly advantageous.

The insert preferably has a material thickness of 2 mm to 25 mm in the area of the surfaces of the tooth tip or it extends over 4% to 50% of the maximum cross-sectional width, preferably it has a material thickness of 3 mm to 15 mm or extends over 6 % to 30% of the maximum cross-sectional width, it particularly preferably has a material thickness of 5 mm to 10 mm or extends over 10% to 20% of the maximum cross-sectional width.

Preferably, the top surface of the tooth tip opposite the cutting speed, also referred to herein as the back surfaces, is not covered with the insert. The crest of the tooth preferably has a square cross-section (cut transversely to its longitudinal direction), resulting in a total of four outer surfaces. Of these four outer surfaces, two opposite surfaces are the lateral cutting surfaces, a third surface is the lower cutting surface (or middle ripper surface) and a fourth surface is the upper (posterior) surface of the tooth, this posterior surface being, for example, concavely curved. This posterior surface of the crest is preferably not provided with the metal matrix composite liner, while the three remaining surfaces (the three cutting surfaces mentioned above) are provided with the metal matrix composite.

The insert made of the metal matrix composite material preferably has a V-shape or a trapezoidal shape in a sectional plane seen transversely to the longitudinal direction of the tooth.

Furthermore, the insert is preferably shell-shaped, i.e. the insert surrounds a core of the excavator tooth head like a shell and with a defined material thickness, this core preferably consisting of a metallic material, in particular a cast material, which can be the metal matrix material.

According to a preferred development of the invention, the insert made of the metal matrix composite material has a greater material thickness in the area of the tip of the tooth head than in other areas of the tooth head. In other words, in this possible embodiment variant, the material thickness of the insert decreases from the tip of the tooth head, for example towards the tooth shank.

According to the invention, the insert made of the metal matrix composite material has a larger proportion of hard material in the area of the tip of the tooth head than in other areas of the tooth head. In particular, it is provided that the insert has a larger proportion of hard material in the area of the tip of the tooth head along the central rib surface than in other areas of the tooth head. The tip of the tooth head is the first to come into contact with the abrasive mineral substances to be removed and is therefore exposed to the greatest wear.

Therefore, according to a further preferred embodiment of the present invention, it can be advantageous if the material thickness of the insert made of the metal matrix composite material gradually decreases from the tip of the tooth tip to the end region of the tooth tip facing the tooth shank.

In addition, according to a preferred embodiment of the invention, it is advantageous if the material thickness of the insert made of the metal matrix composite material decreases continuously towards the rear end region of the tooth tip, in particular tapers out. This can reduce the likelihood of cracking in these areas.

The present invention proposes an alternative method to the prior art mentioned above for applying a tooth wear protection coating, in which, before casting in the tooth mold, an insert made of a metal matrix composite material is introduced, in particular in the tooth tip area, and then surrounded by the metallic casting material during the casting process. The hard materials already contained in the metal matrix composite material or produced during the casting process, such as tungsten carbide, chromium carbide, titanium carbide or the like, with a volume fraction of 20 to 80%, for example, are distributed in the cast material as a matrix and fixed after cooling.

According to a preferred variant of the present invention, at least one tooth for attachment to an excavator shovel of a bucket-wheel excavator is therefore formed from a metal matrix composite material, the metal matrix composite material having an insert made of a hard material cast into a metal matrix material. The insert is a wear protection element. The term “cast in” is to be understood as meaning that the insert is at least partially surrounded by the cast material, namely the metal matrix material.

Hard materials include, for example, ceramics, diamond, carbides or nitrides. Hard materials have in particular a hardness of 950HV30 to 2200HV30, preferably 1500HV30 to 2200HV30.

Preferably, the metal matrix composite consists solely of one or more plies and a metal matrix material. In particular, the entire tooth is formed entirely of the metal matrix composite. The tooth preferably has a tooth head and a tooth shank adjoining it. The toothed shaft is preferably designed in such a way that it can be connected to an excavator shovel. In particular, only the tooth tip is made of the metal matrix composite material, with the tooth shaft being forged, for example. In particular, the tooth tip is connected to the tooth shank by means of welding. A forged one Tooth shank has better mechanical properties than a cast tooth shank, which avoids breaks in the shank area, for example.

The material to be mined with the bucket wheel excavator is, for example, hard rock, such as mineral material, ores, coal, oil sand, limestone, marl, clay, chalk, gypsum and similar raw materials.

The insert comprises, for example, a hard material from the list below, including diamond, tungsten carbide, titanium carbide, boron carbide, niobium carbide, chromium carbide, vanadium carbide, silicon carbide, zirconium carbide, tantalum carbide, boron nitride, silicon nitride, titanium nitride, and/or ceramics, such as aluminum and/or zirconium oxide, or a mixture of these materials. For example, the insert includes a hard material from the list below, including diamond, tungsten carbide, titanium carbide, boron carbide, niobium carbide, chromium carbide, vanadium carbide, silicon carbide, zirconium carbide, tantalum carbide, boron nitride, silicon nitride, titanium nitride, or ceramics, such as aluminum and/or zirconium oxide, or a mixture of these materials.

Preferably, the insert comprises about 20% to 80%, preferably 30% to 75%, most preferably 45% - 55% tungsten carbide, with the remainder of the insert being primarily carbon with a balance.

It is also conceivable that the insert comprises about 20% to 80%, preferably 30% to 75%, most preferably 45% - 55% titanium carbide, the remaining component of the insert being mainly carbon with a balance. The above figures are percentages by volume.

The insert has in particular a porous structure, with the insert preferably having a plurality of pores which are, for example, uniformly distributed and/or formed. For example, the pores are honeycombed. The insert is preferably formed in one piece. The tooth is preferably formed in one piece and manufactured by a casting process.

A metal matrix composite material is to be understood as meaning a material made from a metal matrix material such as steel, in which the insert made from a hard material is cast. The metal matrix material is, for example, a steel with a hardness of about 200-600 HB, in particular 350-500 HB, preferably 450 HB (Brinell) and, for example, an elongation at break of greater than or equal to 1-15%, in particular 2-8% .

The formation of the tooth from a metal matrix composite material offers the advantage of simple manufacturability and a high level of protection against wear, which results from the inlay formed from a hard material.

According to a first embodiment, the insert is made from a powdery and/or granular mixture of, for example, a hard material or tungsten, chromium, niobium, vanadium, boron, titanium, silicon, tantalum or a mixture of these elements by heating. For example, the insert is made from a powdered mixture of tungsten, chromium, niobium, vanadium, boron, titanium, silicon, tantalum or a mixture of these elements by heating. It is also conceivable to produce the insert from a granular mixture of tungsten, chromium, niobium, vanadium, boron, titanium, silicon, tantalum or from a mixture of these elements by means of heating.

The powdered material of one or a mixture of two or more elements selected from tungsten, chromium, niobium, vanadium, boron, titanium, silicon or tantalum is preferably mixed with an additive/reactant such as carbon and/or nitrogen and formed into the insert , Preferably a precursor of the insert is pressed, glued or sintered. The inlay is then placed in a mold that corresponds to the negative mold of the tooth and the hot metal matrix material is poured over it, so that the inlay is surrounded by the metal matrix material and the metal matrix material at least partially infiltrates into the inlay, so that the metal matrix material penetrates the pores of the porous Insert arrived and fills it out. The heat acting on the pressed, bonded or sintered materials during the casting process causes a reaction between the various elements and their reactants, so that, for example, wear-resistant carbides and nitrides such as tungsten carbide, titanium carbide, boron carbide, niobium carbide, chromium carbide, vanadium carbide, silicon carbide, tantalum carbide , boron nitride, titanium nitride, silicon nitride and/or a mixture of these arise. The carbides and nitrides form the liner within the metal matrix material in this embodiment.

It is also conceivable that the insert consists, for example, of a powdered and/or granular mixture of particles (grains), in particular hard materials comprising ceramics such as aluminum and zirconium oxide or hard metal, preferably carbides and nitrides such as tungsten carbide, titanium carbide, boron carbide, niobium carbide, chromium carbide , vanadium carbide, silicon carbide, zirconium carbide, tantalum carbide, boron nitride, silicon nitride and/or titanium nitride, or a mixture of these compounds is prepared, the mixture being mixed, for example with a binder, heated, in particular gassed, and baked. The mixture is preferably heated in a flexible mold, for example, which corresponds to the negative mold of the insert. In particular, the insert is produced by pressing, gluing or sintering the aforementioned powdery material and is placed in the mold that corresponds to the negative shape of the tooth. Preferably, granular tungsten carbide, titanium carbide or niobium carbide is mixed with a binder, heated, in particular gassed, and baked. In the mold, the insert is then surrounded and at least partially infiltrated by the metal matrix material.

The mixture then cools and hardens into a highly wear-resistant insert with a porous structure. This offers a possibility of easily producing different shapes of the insert. A porous structure of the insert is not to be understood as meaning that it necessarily has pores filled with air; rather, the pores are ideally all, realistically for the most part, filled with the metal matrix material, which penetrates into the porous structure of the hard material during the manufacturing process described above .

According to a further embodiment, the insert forms at least partially or completely the surface of the tooth. In particular, the inlay is at least partially covered with the metal matrix material at the surface of the tooth. The metal matrix material is preferably a more ductile, softer material than the material of the liner, as a result of which the metal matrix material wears faster than the liner and is washed out, for example, from the pores located on the surface of the tooth.

According to a further embodiment, the tooth is produced partially or completely by a casting process. Preferably, only the tip of the tooth is produced by a casting process. In the casting process, the insert is positioned in a mold that has the negative shape of the tooth. The metal matrix material is then poured into the mold so that it infiltrates the pores of the insert and at least partially or completely encloses the insert with the metal matrix material. The casting process represents a particularly simple way of producing the tooth, with the insert being able to be easily placed at any desired point within the casting mold and thus wear protection being able to be achieved at any desired point on the tooth.

According to a further embodiment, the tooth has a plurality of inserts. For example, the plurality of inserts includes a plurality of particles, in particular hard material particles. An insert formed from a particle is preferably from 0.2 microns to 6 microns in size, the particles being made, for example, by carburizing tungsten with carbon. Each insert preferably consists of exactly one particle, with the inserts being arranged randomly in the matrix material. It is also conceivable that the tooth has exactly one inlay. For example, three liners are placed within the tooth, preferably extending along the surface of the tooth. A plurality of deposits offers the possibility of arranging them where the wear is greatest. The remaining areas of the tooth can be cast with the less expensive metal matrix material. In particular, the insert has a thickness of about 5 mm to about 50 mm, preferably about 5 mm to about 25 mm. The insert preferably extends over the entire width of the tooth tip.

According to a further embodiment, the insert extends at least partially or completely in the longitudinal direction of the tooth along the surface. In particular, the insert extends completely over the entire length of the tooth tip. The tooth preferably has only one inlay, which represents the simplest and most cost-effective embodiment of the tooth.

According to a further embodiment, the tooth has a tooth tip, with the insert being arranged in the tooth tip. The head of the tooth preferably has a cutting surface which ensures improved removal of the material. The tooth tip preferably points in the direction of rotation of the excavator bucket of the bucket wheel excavator and comes into contact with the material during the excavation process. The tooth preferably has a tooth shank with a fastening area at one end and the tip of the tooth at its opposite end. The tooth shank preferably includes means for attaching the tooth to an excavator bucket. In particular, only the tooth tip has an insert, with the tooth shank being formed exclusively from the matrix material. In particular, the tooth tip and the tooth shaft are designed in one piece, preferably cast. A two-part design is also conceivable. The insert preferably at least partially forms the surface of the tooth tip and extends in particular along the entire surface of the tooth tip. One or more inserts are preferably arranged in the tooth head.

According to a further embodiment, the tooth head has a cutting surface which, when Removal of the material comes into contact with the material and in particular cuts it. The insert at least partially forms the cutting surface. The tooth head preferably has a multiplicity of cutting surfaces, for example three cutting surfaces. The insert preferably extends completely along the entire cutting surface of the tooth tip. In particular, the insert has a V-shaped cross section and is designed, for example, in the shape of a bowl. Preferably, all of the outer surfaces of the tooth tip are cutting surfaces and the insert is, for example, sleeve-shaped so that it extends along the outer surfaces of the tooth tip. The inlay is preferably formed in one piece and the tooth has, in particular, exactly one inlay. Preferably, the core of the tooth is formed solely of the metal matrix material, with the inlay being located only at the portions of the surface of the tooth.

According to a further embodiment, a plurality of inserts are arranged on each cutting surface of the tooth. The inserts are preferably designed in the form of plates and are in particular arranged next to one another.

According to a further embodiment, the tooth tip has a plurality of cutting surfaces, at least one cutting surface being formed largely from the metal matrix material. A large part is understood to mean, for example, more than 60% to 95%, preferably 70% to 90%, in particular 80%. In particular, at least one cutting surface or several outer surfaces are not additionally provided with an insert, which in particular extends completely along the cutting surfaces. As a result, a cutting surface of the tooth tip will wear out more during operation of the tooth than the other cutting surfaces equipped with the insert, as a result of which the tooth, preferably the cutting shape of the tooth, is sharpened.

The subject matter of the present invention is also an excavator shovel for attachment to a bucket wheel frame of a bucket wheel excavator, which has at least one tooth of the type described above. Preferably, each bucket has a plurality of teeth as described above. In particular, at least one tooth or each tooth of an excavator shovel has an insert embedded in matrix material.

• - Positionieren einer Einlage aus einem Hartstoff oder Wolfram, Chrom, Niob und/oder Vanadium, Bor, Titan Silizium und/oder Tantal und vorzugsweise einem Reaktionspartner wie beispielsweise Kohlenstoff und/oder Stickstoff in einer Gussform zum Gießen des Zahns und
• - Gießen des Zahns aus einem Metallmatrixmaterial, sodass die Einlage zumindest teilweise von dem Metallmatrixmaterial des Zahns umschlossen wird.

The subject matter of the present invention is also a method for producing a tooth for attachment to an excavator shovel of a bucket-wheel excavator, comprising the steps:

• - Positioning an insert made of a hard material or tungsten, chromium, niobium and/or vanadium, boron, titanium silicon and/or tantalum and preferably a reactant such as carbon and/or nitrogen in a mold for casting the tooth and
• - casting the tooth from a metal matrix material such that the inlay is at least partially encapsulated by the metal matrix material of the tooth.

The advantages and explanations described with reference to the tooth also apply to the method for producing the tooth, corresponding to the method.

According to one embodiment, the insert is produced before positioning from a powdered and/or granular mixture of a hard material, for example by means of gluing, pressing or sintering.

According to one embodiment, the tooth has a tooth tip and a tooth shank, with the tooth tip being produced by casting and the tooth shank being forged, with the tooth tip then being connected, preferably welded, to the tooth shank.

character list

• 1 eine schematische Darstellung eines Schaufelrades eines Schaufelradbaggers mit einer Mehrzahl von Baggerschaufeln in einer Frontansicht gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;
• 2 eine schematische Darstellung eines Zahns zum Anbringen an eine Baggerschaufel eines Schaufelradbaggers in einer Seitenansicht gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;
• 3 eine Draufsicht auf den in 2 dargestellten Baggerzahn;
• 4 eine schematische Teilansicht eines Baggerzahns gemäß dem Ausführungsbeispiel von 2, wobei der Baggerzahn im vorderen Bereich des Zahnkopfs im Schnitt dargestellt ist.

The invention is explained in more detail below on the basis of several exemplary embodiments with reference to the accompanying figures. show:

• 1 a schematic representation of a bucket wheel of a bucket wheel excavator with a plurality of buckets in a front view according to an embodiment of the present invention;
• 2 a schematic representation of a tooth for attachment to a bucket of a bucket wheel excavator in a side view according to an embodiment of the present invention;
• 3 a top view of the in 2 illustrated bucket tooth;
• 4 a schematic partial view of a bucket tooth according to the embodiment of FIG 2 , whereby the excavator tooth is shown in section in the front area of the tooth head.

The following will first refer to the 1 referenced. This representation shows a bucket wheel 10, for example, of a bucket wheel excavator for mining bulk material or a bridge bucket wheel device for reloading bulk material, in particular in an opencast mine or a storage yard. Such paddles are preferred Vessels used for mining or reloading minerals, ores, sand, clay, gravel, oil sands, coal or other granular materials. The impeller 10 of 1 has an impeller frame 18 which is essentially ring-shaped and has, by way of example, a plurality of segments in the form of part circular rings. A plurality of buckets 12 are attached to bucket wheel frame 18 . This shows, for example, in 1 impeller 10 shown has eight blades 12 which are spaced evenly from one another on the outer circumference of the impeller frame 18 . Each blade 12 may be attached to the blade wheel frame 18 for rotation about a pivot axis.

In operation, the impeller 10 rotates about the central axis of the impeller frame. In the example of 1 the direction of rotation is clockwise as an example. Each bucket 12 preferably has a plurality of bucket teeth 20 in the front area on the cutting edge 14 of the bucket 12, where this bucket 12 engages in the material to be removed. One of these teeth 20 attached to the excavator bucket 12 is shown in detail in FIGS 2 until 4 shown, to which reference is made below.

The 2 until 4 show a tooth 20 for attachment to an excavator bucket, not shown. The tooth 20 comprises a tooth tip 22 and a tooth shank 24, the tooth tip 22 being formed in one piece with the tooth shank 24, for example. It is also conceivable for the tooth shaft 24 and the tooth head 22 to be in the form of separate components and then to be connected to one another, for example by welding. The tooth shank 24 preferably connects directly to the tooth tip 22 and serves in particular to fasten the tooth 20 to an excavator shovel 12 of a bucket-wheel excavator. The tip of the tooth 22 forms the front end of the tooth 20 which, when the tooth 20 is in operation, points in the direction of rotation of the bucket wheel 10 . The tip of the tooth 22 is tooth-shaped and tapers towards the tip of the tooth 20 . The tooth tip 22 has, for example, a triangular or quadrangular cross-sectional area. Preferably, the tooth head 22 has four outer surfaces, namely two mutually opposite lateral cutting surfaces 26, an upper surface which is arranged in opposition to the cutting speed and is therefore referred to herein as the rear surface 28 and a lower surface which is referred to herein as the central ripping surface 30 .

The toothed shaft 24 has, for example, two legs 32, 34 which extend parallel to one another. Each of the legs 32, 34 has bores 36, 38, the respective bores 36, 38 of the other leg 32, 34 are opposite in particular aligned. The bores 36, 38 are used to accommodate fasteners, not shown, for fastening the tooth 20 to an excavator shovel 12. Preferably, the tooth 20 has a stop 40 on the end region of the tooth shaft 24, which serves to position the tooth 20 on the excavator shovel 12 and in the case of a tooth 20 mounted on an excavator shovel 12, it rests against this, in particular the cutting edge 14 of the excavator shovel 12. The toothed shaft 24 is preferably attached to the cutting edge 14 of the excavator bucket 12 .

The tooth 20 is formed from a metal matrix composite material, the metal matrix composite material having an insert 44 made of a hard material cast in a metal matrix material 42 . The insert is preferably formed from a hard material and has a porous structure. The hard material includes, for example, tungsten carbide, ceramics such as aluminum oxide and zirconium oxide, titanium carbide, boron carbide, niobium carbide or chromium carbide or a mixture of these materials. The metal matrix material 28 comprises a more ductile material than the liner 44, such as steel, and the liner 44 is cast. The metal matrix material 42 is infiltrated in particular into the inlay 44 , a materially bonded, firm connection being produced between the inlays 44 made of a hard material and the metal matrix material 42 .

The tooth 20 is preferably produced by a casting process and is in particular formed in one piece. For example, the at least one insert 44 is made from a powdered and/or granular mixture of particles (grains) comprising tungsten carbide, ceramics, such as aluminum and zirconium oxide, titanium carbide, boron carbide, niobium carbide or chromium carbide, or a mixture of these materials, with the Mixture mixed, for example, with a binder, heated, in particular gassed, and baked. In particular, the mixture is heated in a flexible mold, for example, which corresponds to the negative mold of the insert 44 . The mixture then cools and hardens into a highly wear-resistant body with a porous structure. In order to produce the tooth 20 , the insert 44 is placed in a mold that corresponds to the negative mold of the tooth 20 . The metal matrix material is then poured into the mold so that it infiltrates the liner 44 and at least partially or completely encloses it.

The insert 44 is in the embodiment of 2 designed in such a way that it extends over the entire cutting surface of the tooth 20 (see also 4 ). The insert 44 preferably at least partially forms the lateral cutting surfaces 26 and the central ripping surface 30 on the underside of the tooth tip 22 and is a formed in pieces. It is also conceivable that the insert is made up of several segments that are arranged next to one another. The liner 44 is cast into the metal matrix material 42 such that it preferably infiltrates the liner. By way of example, the entire tooth 20 is formed from the metal matrix composite. The rear surface 28 of the tooth tip 22 does not have an inlay 44 , for example, with only the upper ends of the inserts 44 of the cutting surfaces 26 forming part of the rear surface 28 of the tooth tip 22 . Rear surface 28 is formed largely or entirely from metal matrix material 42 . During operation of the tooth 20, this therefore wears out faster than the insert 44, so that the tooth shape of the tooth 20 becomes sharper.

4 shows the tooth 20 according to 2 in a sectional view, wherein the same elements are marked with the same reference numbers. The insert 44 extends over the entire surface of the cutting surfaces 26 and the central rib surface 30 on the underside of the tooth and is preferably cupped and formed in one piece.

Reference List

10

paddle wheel

12

excavator bucket

14

cutting edge

18

paddle wheel frame

20

Tooth

22

tooth head

24

gear shaft

26

cutting surface

28

back surface

30

middle ripper area

32

leg

34

leg

36

drilling

38

drilling

40

attack

42

metal matrix material

44

inlay

Claims (14)

Tooth (20) for attachment to an excavator bucket (12) of a bucket-wheel excavator, the tooth (20) being formed in part from a metal matrix composite material and the metal matrix composite material having an insert (44) made of a hard material cast in a metal matrix material (42). , wherein the insert (44) at least partially forms the surface of the tooth (20), characterized in that the insert (44) made of the metal matrix composite material is arranged at least in the area of the tooth head (22) and this tooth head (22) in the area at least two outer surfaces (26, 30) and that the insert (44) has a larger proportion of hard material in the area of the tip of the tooth tip (22) than in other areas of the tooth tip (22). Tooth (20) after claim 1 , characterized in that the at least two outer surfaces comprise two lateral cutting surfaces (26) and/or a central ripping surface (30). Tooth (20) according to one of the preceding claims, characterized in that the insert (44) in the area of the surfaces of the tooth head (22) has a material thickness of 2 mm to 25 mm or 4% to 50% of the maximum cross-sectional width, preferably a material thickness of 3 mm to 15 mm or 6% to 30% of the maximum cross-sectional width, particularly preferably a material thickness of 5 mm to 10 mm or 10 to 20% of the maximum cross-sectional width. Tooth (20) according to one of the preceding claims, characterized in that the rear surface (28) of the tooth head (22) opposite the cutting speed is not covered with the insert (44). Tooth (20) according to one of the preceding claims, characterized in that the insert (44) has a V-shape or a trapezoidal shape as seen in a sectional plane transverse to the longitudinal direction of the tooth. Tooth (20) according to one of the preceding claims, characterized in that the insert (44) is designed in the shape of a shell. Tooth (20) according to one of the preceding claims, characterized in that the insert (44) has a greater material thickness in the central region of the tip of the tooth head (22) along the central rib surface (30) than in other regions of the tooth head. Tooth (20) according to one of the preceding claims, characterized in that the insert (44) in the area of the tip of the tooth tip (22) along the central ribbed surface (30) has a larger proportion of hard material than in other areas of the tooth tip. Tooth (20) after claim 7 , characterized in that the material thickness of the one layer (44) gradually decreases along the central rib surface (30) towards the end region of the tooth head (22) facing the tooth shank (24). Tooth (20) after one of Claims 7 until 9 , characterized in that the thickness of the material of the insert (44) decreases continuously towards the rear end region of the tooth tip, in particular runs out, without notch formation. Excavator bucket (12) for attachment to a bucket wheel frame (18) of a bucket wheel excavator, characterized in that it has at least one tooth (20) according to one of the preceding claims. Method for producing a tooth (20) for attachment to an excavator bucket (12) of a bucket-wheel excavator and having the features of one of Claims 1 until 10 , comprising - positioning an insert (44) made of a hard material or tungsten, chromium, niobium and/or vanadium, boron, titanium, silicon and/or tantalum in a mold for casting the tooth (20), in particular such that the insert ( 44) is arranged at least in the area of the tooth head (22) of the cast tooth (20), encloses this tooth head (22) in the area of at least two outer surfaces (36, 30), at least partially forms the surface of the tooth (20), and in the area the tip of the tooth tip (22) has a larger proportion of hard material than in other areas of the tooth tip (22), and - casting the tooth (20) from a metal matrix material (42), so that the insert (44) is at least partially covered by the metal matrix material (42) of the tooth (20) is enclosed. procedure after claim 12 , wherein the insert (44) is produced from a powdery and/or granular mixture of a hard material by means of heating prior to positioning. Procedure according to one of Claims 12 or 13 wherein the tooth (20) has a tooth tip (22) and a tooth shank (24) and wherein the tooth tip (22) is produced by casting and the tooth shank (24) is forged, the tooth tip subsequently being connected to the tooth shank (24). becomes.

Images