Excavator tooth for a bucket wheel excavator

Description

[0001] The present invention relates to an excavator tooth for a bucket of a bucket wheel excavator, with a tooth head for engaging in the excavated material and with a receiving shaft for arrangement in or on a receptacle of a bucket of a bucket wheel excavator. STATE OF THE ART

[0002] For example, CN 202450568 U discloses an excavator tooth for a bucket of an earthmoving machine, such as a bucket wheel excavator. The excavator tooth has a tooth head and a receiving shaft, the tooth head being used to engage the excavated material, and the receiving shaft being used to arrange it in or on a receptacle of the bucket of the bucket wheel excavator. The tooth head is made of a different material from the receiving shaft, and the tooth head can be removed from the receiving shaft to replace the tooth head. A bolt connection is used to fasten the tooth head to the receiving shaft. Unfortunately, the bolt connection is only suitable to a limited extent for bucket wheel excavator applications when very hard excavated materials are present, such as rocks with a strength of 10 MPa to 20 MPa and above. The result is often failure of the excavator tooth if the tooth head breaks off from the receiving shaft.

[0003] US Pat. No. 5,224,282 A discloses another excavator tooth for an excavator bucket, which is also used in open-pit mining, for example. The tooth head is also connected to the receiving shaft via a bolt connection, which can also fail if very hard excavation material is present.

[0004] Similar connections between a tooth head and a receiving shaft are also known from DE 37 20 855 C1 and EP 0 681 630 B1.

[0005] A tool for inserting milling teeth is known from WO 83 / 00826 A1.

[0006] EP 1 522 636 A1 discloses a robot for replacing excavator teeth on an excavator.

[0007] The tip of an incisor for an excavator is known from WO 2009 / 003233 A1.

[0008] A holder for a cutting tool is known from EP 0 908 601 A1.

[0009] A tooth holder, for example for an opal mine, is known from AU 2006 284 527 B2 and WO 2007 / 022579 A1.

[0010] A curved tooth for an excavator is known from US 3,606,471 A.

[0011] An incisor for an excavator is known from ES 2 005 287 A6.

[0012] What all excavator teeth with a tooth tip and a shank have in common is that, in plug-in systems secured with bolts, the connection between the tooth tip and the shank can become loose during operation. As wear progresses, the tooth tip becomes increasingly more mobile on the shank. This accelerates wear and the tooth tip can break off from the shank. Increasing the accuracy of the plug-in connection between the tooth tip and shank also increases the manufacturing effort, as the plug-in system must have close tolerances. Complex manufacturing processes are necessary, particularly for longer tapered connections with a smaller taper angle. In particular, simple fit connections with forged or cast surfaces are often not sufficient to effectively prevent the tooth tip from becoming loose on the shank during extended operation. DISCLOSURE OF THE INVENTION

[0013] The object of the invention is the further development of an excavator tooth for the bucket of a bucket wheel excavator with a tooth head and with a receiving shaft, wherein the tooth head and the receiving shaft have as different materials as possible and wherein the connection should be designed to be as mechanically resilient as possible.

[0014] This object is achieved starting from an excavator tooth according to the preamble of claim 1 and starting from a method according to the preamble of claim 10 with the respective characterizing features of claims 1 and 10. Advantageous developments of the invention are specified in the dependent claims.

[0015] The invention includes the technical teaching that the tooth head and the receiving shaft are integrally connected to form the excavator tooth. The core of the invention is a simple design of an excavator tooth with an integral connection between the tooth head and the receiving shaft based on a welded joint. It has been found that with appropriate dimensioning of the welded joint, a sufficient strength of the connection between the tooth head and the receiving shaft can be created, so that even very hard excavation materials can be removed without the excavator tooth failing. The key advantage is that the tooth head and the receiving shaft do not have to be made of the same materials, and the tooth head and the receiving shaft can be manufactured using different manufacturing processes.According to the invention, the tooth head has a higher hardness than the receiving shaft and the receiving shaft has a higher toughness than the tooth head.

[0016] For example, the tooth tip can be manufactured using a casting process, and the shank can be manufactured using a forging process. The tooth tip can also have embedded hard metal plates, and the tooth tip can be hardened using a heat treatment process. In particular, through-hardening of the tooth tip can be provided without this heat treatment also being required for the shank. If the shank is forged, it can be manufactured with high quality at low cost and in high quantities. Furthermore, it is possible to design the geometric tolerances of the shank to be significantly tighter than those of the tooth tip.

[0017] Another advantage is that the tooth tip has a receiving surface which rests against an end face of the receiving shaft to connect the tooth tip to the receiving shank. For example, two flat surfaces formed by the receiving surface and the end face can lie opposite one another, and the two surfaces can be provided with a weld seam at least partially around their outer circumference. The particular advantage of the receiving surface and the end face is that these surfaces do not necessarily have to be machined, and a surface produced by a casting or forging process can already enable sufficiently precise flat contact, particularly if the forging of the receiving shank, for example, includes a calibration step. This further reduces the manufacturing costs for the excavator tooth.Of course, the weld surfaces, weld bevels, and the like necessary for forming the weld joint can be machined, for example, by grinding or milling. However, high precision requirements do not need to be met. The only important thing is that any scale is removed from the surface before the weld joint is created.

[0018] Particularly advantageously, the receiving surface and the end face are complementary to each other, and when the tooth tip is connected to the receiving shank, the complementary surfaces can lie flush against each other. For example, the receiving surface and the end face are flat, but it is also conceivable for the receiving surface and the end face to be crowned or concave, or to have some other topography.

[0019] For example, the receiving surface on the tooth tip can have a projection, and the end face of the receiving shaft can have a recess, so that when the tooth tip is connected to the receiving shaft, the projection engages in the recess. This facilitates the positioning of the tooth tip on the receiving shaft and essentially ensures correct orientation of the tooth tip on the receiving shaft, allowing the weld connection to be made subsequently. Alternatively, the recess can be provided on the receiving surface, and the projection can be provided on the end face.

[0020] The projection particularly advantageously has a roof surface, and the roof surface is delimited by side surfaces that can abut against side surfaces of the recess, in that the side surfaces of the projection and the side surfaces of the recess are designed to complement each other. The complementary design within the meaning of the invention relates to a key-lock principle or a tongue-and-groove principle, in particular such that the complementary surfaces can abut one another essentially flat.

[0021] The side surfaces of the projection and the side surfaces of the recess each form three contact surfaces opposite one another on the projection and the recess. These contact surfaces are designed such that they form a truncated pyramid with respect to one another. All contact surfaces of the projection are designed to be complementary and lie seamlessly on the contact surfaces of the recess to enable force transmission in alternating directions. If the side surfaces of the projection and the side surfaces of the recess are brought into contact with one another, the side surfaces of the projection can form a welding surface area in sections, with the side surfaces of the projection protruding from the recess, thus creating a circumferential welding gap between the tooth tip and the locating shaft.The weld gap, for example, has a triangular cross-sectional area, allowing the weld seam to be easily created from the outside, particularly across its entire circumference, and allowing high transverse forces to be transmitted between the tooth tip and the shank. A further advantage of the circumferential weld seam is that it can be separated with a suitable tool to detach the tooth tip from the shank, particularly to equip the excavator tooth with a new or refurbished tooth tip. The weld seam can then be recreated.

[0022] The invention is further directed to a method for renewing an excavator tooth on a bucket of a bucket wheel excavator, wherein the tooth tip and the receiving shaft of the excavator tooth are integrally connected to one another, namely welded. The method provides that the excavator tooth is first removed from the bucket of the bucket wheel excavator, then the integral connection formed by a weld between the tooth tip and the receiving shaft is severed along the end face of the receiving shaft, this is followed by the gapless positioning of a new or renewed tooth tip on the end face of the receiving shaft and finally the new or renewed tooth tip is once again integrally joined to the existing, i.e. already existing and previously used, receiving shaft, wherein the integral connection is formed by a welded connection.

[0023] The bonded connection between the tooth tip and the shank can be severed using a cutting machine, for example, especially since the bonded connection is a welded joint. After the welded joint has been severed, the receiving surface of the renewed or new tooth tip, which is designed as a flat surface, and the end face of the existing shank can be rejoined to create a new welded joint. Particularly when the receiving surface and the tooth tip are equipped with a projection and a recess, it is easy to create a new weld seam without the receiving surface and / or the end face requiring complex rework. PREFERRED EMBODIMENT OF THE INVENTION

[0024] Further measures improving the invention are described in more detail below, together with the description of a preferred embodiment of the invention, with reference to the figures. It shows: Fig. 1 shows a first embodiment of an excavator tooth with a tooth head and with a receiving shaft in a respective individual arrangement, Fig. 2 shows a view of the excavator tooth with a tooth head which is joined to the receiving shaft, Fig. 3 shows a view of a second embodiment of the excavator tooth with a tooth head and a receiving shaft, wherein the receiving surface of the tooth head has a projection and the end face of the receiving shaft has a recess, and Fig. 4 shows an excavator tooth in a cross-sectional view according to the embodiment of Fig. 3 .

[0025] Fig. 1shows a perspective view of an excavator tooth 1 with a tooth tip 10 and a separate receiving shaft 11. The tooth tip 10 has a receiving surface 12 and extends approximately truncated pyramid-shaped over the receiving surface 12. The receiving shaft 11 has an end face 13, and the receiving surface 12 serves to engage the end face 13 in order to connect the tooth tip 10 to the receiving shaft 11.

[0026] In order to connect the receiving surface 12 to the end face 13, the two surfaces are designed to be complementary to one another, and the complementary, ie matching, design is provided according to the embodiment shown in such a way that the receiving surface 12 and the end face 13 can be brought into contact with one another in a planar manner.

[0027] The receiving surface 12 is bordered by a weld bevel 14, so that the flat surface 12 is smaller than the flat surface of the end face 13. If the receiving surface 12 and the end face 13 are brought flat against one another, the weld bevel 14 creates a circumferential, triangular groove which can be filled with weld metal for welding the tooth tip 10 to the receiving shank 11.

[0028] This shows Fig. 2 the crushing tooth 1 with the tooth head 10, which is connected to the receiving shaft 11 with a weld seam 21. The weld seam 21 surrounds the receiving surface 12 or the end face 13, so that even very large forces can be transferred from the tooth head 10 to the receiving shaft 11.

[0029] The excavator tooth 1 according to the invention allows the material for the tooth tip 10 to be selected independently of the material for the receiving shaft 11. The manufacturing processes for producing the tooth tip 10 and the receiving shaft 11 can also be selected differently. For example, the tooth tip 10 can have a significantly higher hardness than the receiving shaft 11 in order to withstand contact with, for example, very hard excavation material. In order to be able to divert large forces from the tooth tip 10 via the receiving shaft 11 into the bucket of the bucket wheel excavator, the receiving shaft 11 has a material that has very high toughness, which is higher than the toughness of the tooth tip 10. For example, the tooth tip 10 can be produced by means of a casting process, whereas the receiving shaft 11 can be produced by means of a forging process.

[0030] Fig. 3shows a further embodiment of the excavator tooth 1 with a tooth tip 10 and a receiving shaft 11, wherein the tooth tip 10 and the receiving shaft 11 are shown separately in perspective. The embodiment shows the tooth tip 10 with a receiving surface 12, which includes a projection 15, and the end face 13 of the receiving shaft 11 has a recess 16. If the tooth tip 10 and the receiving shaft 11 are joined together, the projection 15 can engage in the recess 16, as in Fig. 4 shown.

[0031] The projection 15 has a roof surface 17, and the roof surface 17 is limited by side surfaces 18 which are complementary to side surfaces 19 of the recess 16.

[0032] Will, as in Fig. 4shown, a weld seam 21 is produced between the tooth head 10 and the receiving shaft 11, the weld seam 21 can be produced in a triangular, circumferential groove which is formed by the geometric design of the side surface 18 of the projection 15 and the side surfaces 19 of the recess 16. The side surfaces 18 have wider dimensions than the side surfaces 19 of the recess 16, so that when the projection 15 is arranged in the recess 16, the side surfaces 18 project beyond a circumferential flat surface bordering the recess 16. This creates the triangular, circumferential groove for producing the weld seam 21. The advantage of the formation of the receiving surface 12 with the projection 15 and the end face 13 with the recess 16 is that, in the sense of a tongue and groove recess, a precisely fitting arrangement of the tooth tip 10 on the receiving shaft 11 can be achieved, so that the weld seam 21 can then be produced in a simple manner.

[0033] In particular, for replacing the tooth tip 10 on the mounting shaft 11, for example, to renew the excavator tooth 1, the weld seam 21 can be cut open, for example, using a cutting machine. A new or renewed tooth tip 10 can then be provided, which is then reattached to the existing mounting shaft 11 by creating a new weld seam 21. List of reference symbols

[0034] 1 excavator tooth 10Tooth head 11Holder 12Holder surface 13End surface 14Weld bevel 15Protrusion 16Recess 17Roof surface 18Side surface 19Side surface 20Weld surface area 21Weld seam

Claims

1. Excavating tooth (1) for a bucket of a bucket-wheel excavator, having a tooth head (10) for engaging in the excavation material, and having a receptacle shaft (11) for disposing in or on a receptacle of a bucket of the bucket-wheel excavator, wherein the tooth head (10) and the receptacle shaft (11) are connected to one another in a materially integral manner, wherein the materially integral connection is formed by means of a welded connection, characterized in that the tooth head (10) has a higher hardness than the receptacle shaft (11), and in that the receptacle shaft (11) has a higher toughness than the tooth head (10).

2. Excavating tooth (1) according to Claim 1, characterized in that the tooth head (10) has a receptacle face (12) which for connecting the tooth head (10) to the receptacle shaft (11) rests on an end face (13) of the receptacle shaft (11).

3. Excavating tooth (1) according to Claim 2, characterized in that the receptacle face (12) and the end face (13) are of a mutually complementary design, and when connecting the tooth head (10) to the receptacle shaft (11) rest on one another in a planar manner.

4. Excavating tooth (1) according to one of Claims 2 or 3, characterized in that the receptacle face (12) and / or the end face (13) are / is at least partially bordered by a weld seam bevel (14).

5. Excavating tooth (1) according to one of Claims 1 or 2, characterized in that the receptacle face (12) on the tooth head (10) has a protrusion (15), and in that the end face (13) of the receptacle shaft (11) has a depression (16) so that the protrusion (15) engages in the depression (16) when the tooth head (10) is connected to the receptacle shaft (11).

6. Excavating tooth (1) according to Claim 5, characterized in that the protrusion (15) has a roof face (17) and lateral faces (18) that delimit the roof face (17) and are designed to be complementary to the lateral faces (19) of the depression (16).

7. Excavating tooth (1) according to Claim 6, characterized in that the lateral faces (18) of the protrusion (15) and the lateral faces (19) of the depression (16) each form three contact faces which are opposite one other on the protrusion (15) and on the depression (16) and which are formed in such a way that they mutually form a truncated pyramid and all contact faces (18) of the protrusion (15) are designed in a complementary manner and rest without a gap on the contact faces (19) of the depression (16) in order to enable a direction-changing force transmission.

8. Excavating tooth (1) according to one of the preceding claims, characterized in that the tooth head (10) is produced by means of a casting method and / or in that the receptacle shaft (11) is produced by means of a forging method.

9. Method for refurbishing an excavating tooth (1) on a bucket of a bucket wheel excavator according to one of the preceding claims, wherein the method comprises at least the following steps: - removing the excavating tooth (1) from the bucket of the bucket-wheel excavator, - severing the materially integral connection formed by means of a welded connection between the tooth head (10) and the receptacle shaft (11) along the end face (13) of the receptacle shaft (11), - positioning a new or refurbished tooth head (10) without a gap on the end face (13) of the receptacle shaft (11), and - joining the new or refurbished tooth head (10) to the existing receptacle shaft (11) in a materially integral manner, wherein the materially integral connection is formed by means of a welded connection.