Wear protection element

Abstract

Wear protection element, namely studded bolt, with a support part (40) which carries a hard material element (30) in or on a receptacle, wherein the hard material element (30) is indirectly or directly supported by a bottom-side support surface (35) of a fastening section (33) on a counter surface (48) of the support part (40), and wherein a transition section (32) is indirectly or directly connected to the fastening section (33), which tapers the outer contour of the hard material element (30) at least partially towards its end facing away from the support surface (35), characterized in that the support part (40) has a preferably obtusely conical first connecting section (47) directly or indirectly connected to the counter surface (48) and a second connecting section (46) directly or indirectly connected thereto, and that these two connecting sections (46,47) taper the cross-section of the supporting part (40) towards the end facing away from the hard material element (30).

Description

The invention relates to a wear protection element, namely a studded bolt, with a support part which carries a hard material element in or on a receptacle, wherein the hard material element is indirectly or directly supported by a bottom-side support surface of a fastening section on a counter surface of the support part. US 2008 / 0315667 A1 discloses a road milling machine with several chisels. One chisel reveals a carrier to which a carbide element is attached. EP 0395610 A2 discloses a chisel with a carrier in which a chisel tip is inserted within an opening. The chisel tip is made of carbide and is coupled to a mounting surface of the carrier. Patent application DE 102011054386 A1 discloses a shank chisel having a chisel head to which a cutting element made of hard material is coupled. DE 29600480U1 and AU 199868079 B3, on the other hand, disclose studded bolts with a carbide element. The studded bolts are made of readily weldable steel and are attached to the outer wall of a soil cultivation tool. The hard metal element consists of tungsten carbide and is designed as a cylindrical molded part. From DE 86 12 330 U1, a studded bolt is known which has a support part made of a readily weldable steel material. The support part is equipped with a receptacle, which can be designed, for example, as a bore or a conical seat. A hard material element, in this case a carbide piece, is arranged in or on the receptacle. If a bore is machined into the support part, a carbide pin is used as the hard material, which is brazed into this bore. The studded bolt serves to protect surfaces subject to high wear. For this purpose, a large number of studded bolts are welded onto the surface to be protected at intervals in a grid pattern. For example, the surface to be protected can be part of an earthmoving tool. During operation, soil is then guided over the surface and the studded bolts.Due to the grid structure, soil accumulates in the spaces between the studded bolts, forming a kind of natural wear protection. The load-bearing part of the studded bolt wears down during machining; the hard material element, however, is subject to less wear due to its material properties. It has been shown that the relatively softer material of the supporting component, compared to the hard material element, is quickly washed away when used with highly abrasive materials. The hard material element then no longer has sufficient support and breaks out. DE 86 12 330 U1 also proposes using an external conical seat for the hard material element instead of a bore. Accordingly, the hard material element is then designed as a ring body and soldered circumferentially to the conical seat. While this variant offers improved protection against erosion with highly abrasive materials, the hard material element is susceptible to breakage under strong impact loads. Here, the ring-shaped design of the hard material element proves to be a particular disadvantage. The object of the invention is to create a wear protection element of the type mentioned above that is particularly stable under both strong impact and strong abrasive loads. This problem is solved by connecting a transition section, either directly or indirectly, to the fastening section with which the hard material element is attached to the support part, which tapers the outer contour of the hard material element at least partially towards its end facing away from the support surface, by having the support part, either directly or indirectly, a preferably truncated conical first connecting section and, directly or indirectly, a second connecting section thereafter, and by having these two connecting sections taper the cross-section of the support part towards the end facing away from the hard material element. This design ensures that the fastening section of the hard material element covers the underlying area of ​​the supporting component, thus protecting it from erosion. The tapered geometry of the hard material element is also optimized for impact resistance, as it more effectively dissipates the energy of impacting objects, such as stones. Specifically, the impact forces are vectorially distributed into longitudinal and transverse forces, resulting in optimized overall stress distribution on the studded bolt. A further advantage is the reduced material consumption of the hard material compared to, for example, cylindrical components, due to the geometry of the hard material element. The design with the two tapered connecting sections is characterized by good weldability, as it optimizes the current flow during the welding process. According to a preferred embodiment of the invention, the hard material element can terminate with a convex end section facing away from the support surface. This design has the advantage that impact forces acting vertically to the bottom-side support surface can be reliably absorbed. Furthermore, this design is also stress-optimized, as sharp-edged transitions are avoided in the particularly vulnerable head region of the hard material element. This also results in improved material dissipation and, consequently, improved wear resistance. The tapered section is particularly advantageous, featuring at least one truncated conical area. This design simplifies the automated assembly of the hard material element to the supporting component, as it provides a defined point of engagement for an assembly tool. It is also conceivable to design the tapered section to be at least partially concave. This allows for a reduction in the hard material volume and thus the amount of material used. However, it is also conceivable to design the tapered section to be at least partially convex. This results in a more massive cross-sectional design of the hard material element, leading to a more robust construction. Ultimately, the choice of tapered section design also depends on the specific application. While convex areas are more advantageous in highly abrasive media, concave areas can be used, for example, with materials that tend to quickly clog the spaces in the grid between the studs. Furthermore, concave designs are well-suited for rotating tools due to the lower mass of the hard material. The blunt conical geometry offers a good compromise for many machining tasks. The wear protection element is particularly preferred in that the fastening section forms a circumferential collar with a convex curvature on its outer circumference. This convex curvature is again designed to be wear-optimized and offers only minimal resistance to the abrasive material. Furthermore, this design reduces the risk of fracture of the hard material under impact loads. In particular, notch stresses are avoided. If a recess is incorporated into the support surface of the hard material element, the mass of the hard material can be further reduced without significantly impairing the wear characteristics. Furthermore, this measure increases the contact area between the supporting part and the hard material element, resulting in greater shear strength. For reliable mounting of the hard material element, the invention provides that the support part has a recessed receptacle for the hard material element, which is at least partially surrounded by a shell. The hard material element can be reliably and correctly aligned on the shell during mounting. According to one embodiment of the invention, a wear protection element can be configured such that a cavity is formed, at least in some areas, between the outer contour of the hard material element and the inner wall of the sheathing part. Machining or waste material can compact into this cavity, resulting in natural wear protection and, with certain machining or waste materials, reducing the abrasive attack on the studded bolt. If the wear protection element is designed such that the counter surface of the supporting part is formed by a base part, and that the outer shell part rises from the base part, then a simple design is achieved that is easy to manufacture. Particularly preferably, the second connection section directly features a contact element that serves for contacting during the welding process. This contact element can, for example, be designed as an aluminum tip. The object of the invention is also achieved with a combination consisting of a weldable workpiece and a wear protection element according to one of claims 1 to 10. In such a combination, it can be provided according to the invention, in particular, that a bead-shaped weld area is formed on the outside in the transition area between the base part and the shell part. This weld area can, in particular, be formed circumferentially. The bead-shaped weld area has a higher wear hardness than the supporting part and thus protects the transition area of ​​the supporting part to the workpiece and therefore serves as protection against washout. The invention is explained in more detail below with reference to an embodiment illustrated in the drawings. The drawings show: Fig. 1 in a side view of a workpiece onto which a studded bolt surrounded by a ceramic ring is mounted; Fig. 2 the studded bolt according to Fig. 1 welded onto the workpiece in a side view; Figs. 3 and 4 various wear states of the studded bolt according to Fig. 2 in a side view; and Figs. 5, 6, 7 to 8 the representations according to Figs. 1, 2, 3 to 4 in side view and in full section. As shown in Figures 1 and 5, the wear protection element, which in this case is designed as a studded bolt, has a support part 40 and a hard material element 30. The support part 40 is made of a weldable material with good electrical conductivity. It has a base part 42 from which an annularly circumferential sleeve 41 rises. The sleeve 41 encloses a cylindrical cavity 44 and is also cylindrical on its outer contour. The base part 42 forms a bottom-side counter surface 48 facing the cavity 44. Adjoining the base part 42, away from the sleeve 41, is a first tapered section 47 with a truncated conical shape. Directly connected to this first tapered section 47 is a second tapered section 46, also with a truncated conical geometry. The cone angle of the first tapering section 47 is larger than that of the second tapering section 46.A bore is provided in the second tapered section 46, the axis of which is aligned with the central longitudinal axis ML of the studded bolt. A contact element 45, made of a highly electrically conductive material, for example aluminum, is pressed into the bore. The support element 40 accommodates a hard material element 30, made, for example, of ceramic or hard metal, within the cavity 44. The hard material element 30 has a mounting section 33 with a base-side support surface 35. The support surface 35 is oriented orthogonally to the central longitudinal axis ML. A recess 34 is formed in the support surface 35. A transition section 32 adjoins the mounting section 33, and an end section 31 adjoins the transition section 32. The purpose of the transition section 32 is to taper the cross-section of the hard material element 30 from the mounting section 33 to the end section 31. In the present embodiment, the transition section 32 is designed with two adjacent obtuse conical geometric regions. It is also conceivable to use only one obtuse conical section. It is also conceivable within the scope of the invention to use one or more concave or convex sections.It is also conceivable that the tapered section between tapered areas has cylindrical sections. The end section 31 is dome-shaped and connects directly to the truncated conical area of ​​the transition section 32. A plumb bob is used, for example, to mount the hard material element 30 in the cavity 44 of the support part 40. This is positioned in the transition area between the support surface 35 and the counter surface 48. The hard material element 30 is fixed to the support part 40 via the plumb bob connection. In the assembled state, the area between the outer contour of the transition section 32 and the inner contour of the sleeve 41 remains unfilled, so that the cavity 44 forms free areas in this respect. As can be seen in Fig. 5, the studded bolt, composed of the support part 40 and the hard material element 30, is rotationally symmetrical about the central longitudinal axis ML. For the welding process, a ceramic ring 10 is used, which has a cylindrical inner recess 12 that receives the studded bolt. The ceramic ring 10 has a lower support surface 13 that can be placed on the surface of a workpiece 20. The workpiece 20 is a component, for example, of an earthmoving machine, and the surface of this component is to be protected with a wear protection arrangement consisting of a plurality of studded bolts. The studded bolts are arranged on the surface of the workpiece, preferably in a grid pattern. The ceramic ring 10 is provided with recesses in the area of ​​the support surface 13, which serve as gas outlets 11. To attach the studded bolt to the workpiece 20, a welding tool (not shown) is attached to the ceramic ring 10, which makes electrical contact with the support element 40.A welding current is then introduced into the support part 40, generating an arc between the contact element 45 and the surface of the workpiece 20. This melts the surface of the workpiece 20. The two tapered sections 46, 47, and the contact element 45 are also melted. The studded bolt then sinks into the molten metal, and after cooling, a solid weld is formed in the transition area between the base part 42 and the workpiece 20, as shown in Figures 2 and 6. The welding process is designed such that a circumferential, bead-shaped weld area is formed in the transition area between the base part 42, the sleeve part 41, and the surface of the workpiece 20. The weld material accumulated here serves as wear protection for the transition area. Figures 3 and 7 show the condition of the studded bolt after a certain period of use. As these drawings show, the outer shell 41 wears down progressively during machining, and the material being worked in the cavity 44 also becomes compacted. This material forms a kind of natural wear protection, protecting both the inner surface of the outer shell 41 and the hard material element 30. Figures 3 and 7 also show that the weld area 43 wears down progressively due to the wear. Figures 4 and 8 show a further worn state of the studded bolt. The sleeve 41 and the welded section 43 are now completely worn away. As these drawings clearly show, the base part 42 is now covered by the overlying hard material element 30, so that this area, which serves for the reliable fastening of the hard material element 30 to the workpiece 20, is reliably protected. Due to the small distance of the fastening section 33 from the surface of the workpiece 20, the base part 42 is only slightly eroded in the edge areas, as can be seen in Figures 4 and 8. The distance between the top surface of the workpiece 20 and the support surface 35 of the hard material element 30 should therefore be less than 5 mm, preferably less than 3 mm.This ensures that the hard material element 30 can wear down continuously over its entire service life, resulting in optimized wear properties also in connection with the geometric design of the hard material element 30.

Claims

Wear protection element, namely studded bolt, with a support part (40) which carries a hard material element (30) in or on a receptacle, wherein the hard material element (30) is indirectly or directly supported by a bottom-side support surface (35) of a fastening section (33) on a counter surface (48) of the support part (40), and wherein a transition section (32) is indirectly or directly connected to the fastening section (33), which tapers the outer contour of the hard material element (30) at least partially towards its end facing away from the support surface (35), characterized in that the support part (40) has a preferably obtusely conical first connecting section (47) directly or indirectly connected to the counter surface (48) and a second connecting section (46) directly or indirectly connected thereto, and that these two connecting sections (46,47) taper the cross-section of the supporting part (40) towards the end facing away from the hard material element (30). Wear protection element according to claim 1, characterized in that the hard material element (30) terminates with a convex end section (31) facing away from the support surface (35). Wear protection element according to claim 1 or 2, characterized in that the tapered section (32) has at least one obtuse conical area. Wear protection element according to one of claims 1 to 3, characterized in that the tapered section (32) has at least one concave and / or one convex area. Wear protection element according to one of claims 1 to 4, characterized in that the fastening section (33) forms a circumferential collar which has a convex curvature on its outer circumference. Wear protection element according to one of claims 1 to 5, characterized in that a recess (34) is incorporated into the support surface (35). Wear protection element according to one of claims 1 to 6, characterized in that the support part (40) has a recessed receptacle for the hard material element (30), which is at least partially surrounded by a jacket part (41). Wear protection element according to one of claims 1 to 7, characterized in that a cavity (44) is formed at least partially between the outer contour of the hard material element (30) and the inner wall of the jacket part (41). Wear protection element according to one of claims 1 to 8, characterized in that the counter surface (48) of the support part (40) is formed by a base part (42) which preferably has a cylindrical outer contour, and from which the jacket part (41) rises. Wear protection element according to one of claims 1 to 9, characterized in that the second connecting section (46) carries a contact element (45). Combination consisting of a weldable workpiece (20) and a wear protection element according to one of claims 1 to 10. Combination according to claim 11, characterized in that a bead-shaped weld area (43) is formed on the outside in the transition area between the base part (42) and the jacket part (41). Combination according to claim 12, characterized in that the bead-shaped welding area is formed in a ring-shaped circumferential manner.

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