EP3250788B1 - Pick, in particular a round-shank pick - Google Patents

Description

The invention relates to a chisel, in particular round shank chisel, with a chisel head and a chisel shank, wherein the chisel head is formed of a hard material, in particular tungsten carbide, at least of a base part and a cutting element connected to the base part, the base part following the cutting element its outer surface has a wear-resistant layer, which covers at least one of the cutting element facing portion of the outer surface of the base part and wherein a cutting element facing the end face of the wear-resistant layer is covered by the cutting element.

The invention also relates to a method for coating at least a portion of an outer surface of a chisel head of such a chisel, in particular a round shank chisel, with a wear-resistant layer, wherein in a second process step, a cutting element on a surface of the wear-resistant layer facing the cutting element and a front mating surface of a base part of the chisel head is soldered.

From the DE 90 16 655 U1 is a chisel known. The chisel described in the document has a base body with a carbide tip. On a tip of the adjacent outer surface of the body, a wear-resistant layer of a hard material (hard metal or ceramic) is arranged. The outer surface of the tip merges smoothly into the surface of the wear-resistant layer. The main body has a circumferential recess, in which the hard material is applied. The hard material may for example be sprayed onto the bit. The main body is frustoconical at its front end. The tip has a corresponding frusto-conical axial recess in which the frusto-conical end of the body is received and thereby the tip is positioned and guided laterally. In practical use, the axial recess leads to disadvantages, as the Wall thickness of the tip is reduced in the axial recess. At the conclusion of the axial recess, a comparatively sharp edge is formed between the conical surface and the bottom surface of the recess. In this area, especially at a laterally acting on the tip mechanical stress, high voltage peaks formed. These spikes lead in the relatively small wall thickness of the tip in this area increasingly to break the tip made of a brittle hard material and thus to the failure of the bit. Another disadvantage arises from the possible manufacturing method for such an arrangement. In order to avoid damage or destruction of the tip, in particular in a required thermal treatment during application of the wear-resistant layer, the tip is only after the wear-resistant layer has been applied to the body attached to the body, preferably soldered. The tip then sits on a circumferentially arranged to the frustoconical end surface of the body. Due to the manufacturing process, the end face of the wear-resistant layer does not close evenly with the peripheral surface on which the tip rests, but is set back in the context of manufacturing tolerances with respect to this or is arranged in a projecting manner. Thus, no uniform soldering gap is formed between the contact surface tip, the circumferential surface of the main body and the end face of the wear-resistant layer, as in the embodiment shown DE 90 16 655 U1 is also shown. The non-uniform soldering gap leads to insufficient soldering, which can loosen in use and lead to the loss of the tip.

DE 35 19 101 U1 discloses a chisel for a road milling machine having a chisel shaft. A chisel head made of tungsten carbide is connected to the chisel shaft. In the area of the chisel head several sleeves made of hard metal are arranged, which are inserted into each other and surround the chisel shaft.

EP 0 412 287 A2 discloses a round shank bit with a chisel head and a chisel shank. In the area of the chisel head, a receptacle is arranged, in which a chisel tip made of hard metal is attached. The chisel head is with one Wear protection layer, which is applied in the plasma powder build-up welding process surrounded.

Another round shank chisel is off DE 40 39 217 A1 known. Also this round shank chisel has a chisel head, on which a chisel shank is integrally formed. The chisel head is equipped with a carbide tip. Subsequent to the tip made of hard metal, a wear-resistant layer of hard material is applied to the chisel head.

WO 2009/072958 A1 discloses a chisel carrying a chisel point in the area of its chisel head. In this case, a receptacle is incorporated in the chisel head, which extends in the direction of the central longitudinal axis of the chisel. In this recording, a chisel tip approach is maintained. The approach has a cylindrical outer surface on which a carbide ring is pushed.

DE 35 31 787 C1 discloses a tooth for a digging device, such as an excavator bucket.

It is therefore an object of the invention to provide a chisel of the type mentioned with an improved mechanical strength. It is a further object of the invention to provide a method for coating a chisel head and another method for producing such a chisel head.

The chisel-related object of the invention is achieved in that the base part has an axially aligned recess for receiving a fastening portion of the cutting element, that the base part circumferentially to the recess has a cutting element facing the counter surface and that the counter surface and the end face of the wear-resistant layer form continuous flat surface or that the end face of the wear-resistant layer is brought to the opposite surface. Since the fixing portion of the cutting element is held in the recess of the base part, thin-walled portions of the cutting element, which are strong outer Force effects are avoided avoided. This significantly reduces the breakage risk for the tip. The flat surface formed by the mating surface and the end face allows the formation of a uniform soldering gap between this flat surface and the cutting element. It can be achieved as an optimized soldering between the cutting element and the base part of the bit, which is not separated even under heavy mechanical load. Characterized in that the base part for connection to the cutting element has a recess in place of a lug, the continuous flat surface between the mating surface and the end face of the wear-resistant layer manufacturing technology can be easily manufactured.

Preferably, the wear-resistant layer is brought with its front side to the opposite side, so that the transition region is effectively protected against leaching. For example, the wear-resistant layer can be brought up to less than 1 mm to the opposite surface.

For connection to a bit holder, the bit head is preferably integrally connected to a bit shaft. The chisel shaft can be designed as a round shaft.

Preferably, the wear-resistant layer is received in a recess of the base part. The recess is provided circumferentially to the counter surface on the outer surface of the base part. Advantageously, it can be provided that the introduced wear-resistant layer terminates radially on one side with the cutting element and on the opposite side with the outer surface of the base part following the recess.

The wear-resistant layer may be formed by a coating which is coated on the base part. The wear-resistant layer can also be formed by a separate hard material element, which is connected to the base part, for example, a material fit. Conceivable here is the use of a soldered carbide ring or individual, adapted to the base part corresponding segments made of a hard metal, which are arranged in a regular or irregular arrangement.

According to a particularly preferred embodiment variant of the invention, it may be provided that the mating surface and the end face are formed as parting surfaces created in one operation, in particular as cut surfaces or as ground surfaces or as milled surfaces, or that the end face as a during an application process, in particular formed during a welding process, the wear-resistant layer formed impression surface of a resting on the counter surface and radially over the counter surface protruding base of an auxiliary tool. In both cases, a continuous flat surface is formed between the mating surface and the end surface. As a result, we achieve a uniform soldering gap and thus an optimized, loadable solder joint between the surface formed by the mating surface and the end face and the cutting element.

The flow behavior of the solder can be improved by providing the mating surface and / or the end surface as smooth surfaces or as surfaces having a predetermined roughness in a range from Rz = 4 μm to Rz = 280 μm or as surfaces with grooves introduced having a groove depth in one region are carried out from 2 .mu.m to 500 .mu.m. The roughness or the grooves can be generated, for example, during the separation process in the preparation of the separation surfaces or as an impression of the base to the desired specification.

The cutting element is exposed to high mechanical loads in use. In order to achieve a secure connection between the cutting element and the base part, it is provided according to the invention that the cutting element circumferentially to its mounting portion forms a support surface, that the support surface at least partially covers the counter surface and the end face and that between the support surface and by the counter surface and the end face formed continuous surface is formed a first Lötfuge. In addition, it may also be provided that between an outer surface of the Fixing portion and an inner surface of the recess, a second Lötfuge is formed and / or that between a end face of the fixing portion and a bottom surface of the recess, a third Lötfuge is formed. The solder joints preferably merge into one another, so that a continuous soldering is present over the entire interface between the cutting element and the base part as well as the cutting element and the end face of the wear-resistant layer.

The abrasive load applied to the base member is greatest following the cutting element and decreases toward the end of the bit head facing the bit shank. At the same time, the cutting element is held with its attachment portion in the recess at the front end of the base part.

In order to protect the region of the holder of the cutting element and thus to avoid loss of the cutting element, it can be provided that the wear-resistant layer encloses in axial alignment at least the section of the chisel head in which the recess is made.

According to two alternative variants of the invention, it may be provided that the wear-resistant layer has a uniform layer thickness or that the wear-resistant layer has a varying layer thickness. A wear resistant layer with a uniform layer thickness is easy and inexpensive to produce. Due to a varying layer thickness, the wear-resistant layer can be adapted to the actual loads in the different areas of the chisel head.

In order to adapt the layer thickness to the local stresses, it may be provided that the layer thickness of the wear-resistant layer, starting from its end face facing the cutting element, is reduced towards its end facing the cutter shank, or that the layer thickness of the wear-resistant layer starts from their facing the cutting element End face, towards its end facing the chisel end enlarged. By means of a layer thickness which increases in the direction of the chisel shaft, a conical outer contour of the chisel head can be obtained with a constant diameter of the base part in the region of the coating, through which abraded material is led away from a chisel holder in which the chisel is arranged. In the case of a layer thickness which decreases in the direction of the drill collar, the greatest layer thickness in the region of the maximum abrasive load is arranged immediately after the cutting element. As a result, the layer thickness is adapted to the particular abrasion present, resulting in comparable service lives for the different regions of the wear-resistant layer.

Another possibility of adapting the layer thickness of the wear-resistant layer to the local loads is that an outer surface of the wear-resistant layer is convexly curved along its longitudinal extent or that the outer surface is concavely curved along its longitudinal extent or that the outer surface alternately along its longitudinal extent has concave and convex curved sections. In addition, the shaping of the outer surface can influence the material flow of the spacer material. Thus conveys a convex surface of the wear-resistant layer, the space material immediately after the cutting element to the outside. With a suitable adaptation of the outer contour of the cutting element and the convex shape of the outer surface of the wear-resistant layer can be achieved that the space material is deflected by the cutting element and the wear-resistant layer in approximately the same direction, thus creating a uniform flow of material, in the further from The cutting element removed areas of the chisel head are relieved. By convexity of the outer surface, the front coated portion facing the cutting element provides less resistance to the spacer material while being more strongly deflected outwardly from the rear portion. As a result, a uniform loading of the wear-resistant layer along the flow direction of the spacer material can be achieved. By alternating concave and convex Areas may deposit space in the concave areas. This leads to an additional wear protection, since the moving space material in these areas does not pass directly past the wear-resistant layer.

Furthermore, it can be provided that an internal angle is formed between the surface of the cutting element and the outer surface of the wear-resistant layer in its transition. A soldering joint ending in this transition region is thereby set back from the main flow of the passing-off material and thus protected. This protective effect is exacerbated by the fact that waste material deposited in the interior angle and can additionally shield the solder joint from the abrasive attack of the pasting off space material.

A further embodiment of the invention may comprise a segmental coating or individual segments formed from one or more hard metals, the assembly being carried out by means of fixing processes known from the prior art, such as soldering, gluing, build-up welding or the like.

According to one development of the invention, it can be provided that the wear-resistant layer covers at least one surface section of the cutting element adjoining the support surface. The wear-resistant layer thus covers the contiguous outer surfaces of both the base part and the cutting element. As a result, both the cutting element and the base part are protected from abrasive wear in the particularly loaded transition region from the cutting element to the base part. In particular, the solder joint formed between the bearing surface of the cutting element and the base part is arranged protected, so that no hard materials can be pushed from the outside into the solder joint and the cutting element can be separated from the base part.

The strength of the connection between the cutting element and the base part can be further improved by the fact that between the wear-resistant layer and the surface portion of the cutting element is a Lötfuge (fourth Lötfuge) is formed. The cutting element is thus connected to the base part by soldering along its support surface and along its surface section adjoining the support surface.

Advantageously, it can be provided that the wear-resistant layer projects in the direction of a central longitudinal axis of the bit head over the counter surface and / or that the wear-resistant layer and the counter surface form a cup-shaped receptacle for the cutting element. Preferably, the wear-resistant layer is attached to the base part and then the cutting element is soldered. By the above wear-resistant layer or the cup-shaped receptacle, the cutting element can be easily and accurately aligned positioned on the base part and soldered to it. In this case, the cutting element is held in its position during the soldering process by the wear-resistant layer, which surrounds the cutting element in its region facing the base part.

The object of the invention relating to the method for coating a chisel head of a bit according to the invention is achieved by fixing an auxiliary tool on the base part of the chisel head such that it rests on the counter surface at least with a portion of a contact surface, that in a first method step the outer surface is coated with the wear-resistant layer and then that the auxiliary tool is removed. The wear-resistant layer is thus applied to the outer surface of the base part of the chisel head, whereby this is protected in later use from mechanical damage and abrasion. The auxiliary tool prevents that in the coating process, the mating surface on which the cutting element is soldered in the second manufacturing process, is coated with. It thus remains a defined area for soldering the cutting element obtained. Furthermore, with the auxiliary tool, the outer shape of the wear-resistant layer is predetermined in its transition region to the cutting tool, so that here too a predetermined soldering surface is produced to the cutting tool.

According to a preferred variant of the method, it can be provided that the wear-resistant layer is applied to the outer surface of the bit such that it rests with its end face on at least a portion of the contact surface of the auxiliary tool and / or that it is adjacent to a surface area of the auxiliary tool adjacent to the contact surface with a deviating from the contact surface spatial orientation. Depending on the design of the auxiliary tool so a different contour of the later adjacent to the cutting element surface of the wear-resistant layer can be made. Thus, the contour of the cutting element facing surface of the wear-resistant layer can be adapted to the contour of the cutting element. The contour of the auxiliary tool and thus the contour of the surface of the wear-resistant layer are predetermined so that it follows the contour of the cutting element when soldered cutting element. This ensures that a uniform soldering gap is formed along the interface between the cutting element and the wear-resistant layer. If the auxiliary tool, for example, with its contact surface radially over the mating surface of the base part, so the wear-resistant layer can be brought up to the contact surface. It is thus formed an end face of the wear-resistant layer, which is arranged radially to the counter surface of the base part and forms a flat surface with this. The cutting element can be created in a subsequent manufacturing step with its bearing surface against the counter surface and the end face and connected to them by soldering. Alternatively or additionally, it can be provided that the wear-resistant layer is applied to a surface adjacent to the contact surface of the auxiliary tool. This adjacent surface is oriented to follow the contour of the surface of the cutting element adjacent the bearing surface. If the cutting element is applied in a subsequent manufacturing step with its contact surface against the counter surface of the base part, its surface adjoining the bearing surface, spaced apart by a defined wide soldering gap, opposes the wear-resistant layer. The wear-resistant layer thus encloses a part of the outer surface of the cutting element. The cutting element can be connected to the base part by soldering, wherein the soldering gap along the Forming interface between the cutting element on one side and the counter surface and the wear-resistant layer on the other side.

For producing a bit according to the invention, it may be provided that the base part of the bit head is made in a size extended towards its final dimension in the direction of the cutting element, that the wear-resistant layer is applied to the outer surface of the extended base part and that subsequently the base part together with the wear-resistant Layer is shortened along a dividing line. The separating surface thus formed constitutes a continuous, flat surface between an opposing surface formed as the front end of the base part and the end face of the wear-resistant layer. The flat surface makes it possible to form a uniform soldering gap to the cutting element which covers the counter surface and the end surface in a next process step is soldered to the base part.

Preferably, the wear-resistant layer can be applied by a welding process to the outer surface of the chisel head. The welding process enables the production of a cost-effective and durable wear-resistant layer. The disadvantage of the welding process that an open end-side end surface of the coating obtained in its position only inaccurately set and therefore no continuous, flat surface can be produced to an adjacent mating surface is canceled by the separation process described.

A durable wear-resistant layer and thus a durable chisel can be obtained by using as wear-resistant layer a layer of a hard material, in particular hard metal, and / or an iron alloy and / or a nickel alloy and / or a cobalt alloy and / or a titanium alloy and / or tungsten carbide and / or titanium carbide is applied.

Figur 1

in einer perspektivischen Seitenansicht einen Meißel mit einem Meißelschaft und einem Meißelkopf mit einer verschleißfesten Schicht,

Figur 2

den in Figur 1 gezeigten Meißel in einer seitlichen, zum Teil als Schnitt ausgeführten Darstellung,

Figur 3

einen Ausschnitt des in Figur 2 gezeigten Meißels,

Figur 4a-4i

in seitlicher Schnittdarstellung einen Ausschnitt des Meißelkopfs mit unterschiedlichen Ausführungsformen der verschleißfesten Schicht,

Figur 5

in einer weiteren seitlichen Schnittdarstellung einen Ausschnitt des Meißelkopfs mit einem Hilfswerkzeug,

Figur 6

in einer weiteren seitlichen Schnittdarstellung einen Ausschnitt eines Meißelkopfes in einer zu seiner Endabmessung in Richtung zum Schneidelement verlängerten Größe,

Figur 7

in einer seitlichen Schnittdarstellung einen Ausschnitt einer in axialer Richtung überstehenden verschleißfesten Schicht,

Figur 8

in einer seitlichen Schnittdarstellung einen Ausschnitt eines Meißelkopfes in einer weiteren Ausführung einer in axialer Richtung überstehenden verschleißfesten Schicht und

Figur 9

in einer seitlichen Schnittdarstellung einen Ausschnitt des Meißelkopfs mit einem Hilfswerkzeug,

The invention will be explained in more detail below with reference to an embodiment shown in the drawings. Show it:

FIG. 1

in a perspective side view of a chisel with a drill collar and a chisel head with a wear-resistant layer,

FIG. 2

the in FIG. 1 shown chisels in a lateral, partly executed as a section representation,

FIG. 3

a section of the in FIG. 2 shown chisel,

Figure 4a-4i

in a lateral sectional view of a section of the chisel head with different embodiments of the wear-resistant layer,

FIG. 5

in a further lateral sectional view of a section of the chisel head with an auxiliary tool,

FIG. 6

in a further lateral sectional view of a section of a chisel head in an extended to its final dimension in the direction of the cutting element size,

FIG. 7

in a lateral sectional view of a section of a projecting in the axial direction wear-resistant layer,

FIG. 8

in a lateral sectional view of a section of a chisel head in a further embodiment of a projecting in the axial direction wear-resistant layer and

FIG. 9

in a side sectional view of a section of the chisel head with an auxiliary tool,

FIG. 1 shows in a perspective side view of a chisel 10 with a drill collar 50 and a chisel head 40 with a wear-resistant layer 30. The chisel 10 is formed as a round shank chisel. The chisel head 13 is a cutting element 20, consisting of a hard material, such as carbide, assigned. This is connected to a conically tapered to the cutting element 20 base portion 41 of the chisel head 13, in the present embodiment by soldering. In a region facing the cutting element 20, the base part 41 is coated around the cutting element 20 with the wear-resistant layer 30. The wear-resistant layer 30 consists of a hard material and is applied to the base part by a welding process. In the embodiment shown, the wear-resistant layer 30 is formed of hard metal. It may also be made of an iron alloy, a nickel alloy, a cobalt alloy, a titanium alloy, tungsten carbide or titanium carbide.

Starting from the base part 41, the chisel head 40 widens via a transition region 41.2 to a collar 41.3 with a constant outside diameter. The federal government goes over to the chisel 50. To the drill collar 50, a fastening sleeve 51 is arranged. The fastening sleeve 51 is designed as a clamping sleeve, which is formed from a resilient material, such as steel sheet. As in FIG. 2 shown, it has a longitudinal slot which is bounded by sleeve edges. Due to the longitudinal slot, the mounting sleeve diameter can be varied with the sleeve edges moving toward each other (small diameter) or spaced apart from each other (large sleeve diameter). In this way, different clamping states can be achieved. On the mounting sleeve designed as a wear protection disk support member 52 is mounted. This support member 52 has a circular cross section and is penetrated by a bore. In this case, the bore is dimensioned such that the fastening sleeve is held in a bias state with reduced outer diameter relative to its relaxed state. The outer diameter thus produced is selected such that the mounting sleeve 51 with little or no effort in a bit holder of a chisel holder, not shown, can be inserted. The insertion movement is limited by means of the support element 52. Upon further insertion of the drill collar 50 in the bore, the support member 52 is moved in a non-covered by the mounting sleeve 51 portion of the drill collar 50. Then, the mounting sleeve 51 jumps radially and clamped in the bore of the chisel holder. In this way, the bit 10 is axially captive, but freely rotatably supported in the circumferential direction. As FIG. 1 further shows, the support member 52 is formed toward the chisel head 40 toward a 52.2 surrounded by an edge support surface 52.1 for supporting the collar 41.3 of the chisel head 40 from. The edge 52.2 is pierced by edge recesses 52.3.

The cutting element 20 has, starting from a front cutting tip 21, a convex-shaped cutting surface 22, which merges into a radially ending with the wear-resistant layer 30 base 23.

The chisel will be used around its in FIG. 2 shown center longitudinal axis M rotatably mounted on a bit holder mounted on a rotating roll carrier. Due to the rotation of the roller carrier, the cutting element 20 penetrates into the material to be removed, for example asphalt or soil, and comminutes it. The space material slides past the bit head 40 and is thereby discharged through the base portion 41 with the circumferential, wear-resistant layer 30 and the transition region 41.2 to the outside. A chisel carrier, in which the chisel 10 is held, is best protected against abrasion by the space material.

The mechanical load of the chisel head 40 is greatest in the region of the cutting element 20. Therefore, the cutting element 20 is made of a hard material, resulting in a long service life of the bit 10. In order to increase in particular the service life of the base part in its mechanically heavily loaded area adjacent to the cutting element 20, the wear-resistant layer 20 is applied there.

FIG. 2 shows the in FIG. 1 shown chisel 10 in a lateral, partially executed as a section representation. The cut exposes a portion of the base 41 of the bit head 40. As can be seen there, a recess 44 is provided in the base part 41 at the end of the base part 41 facing the cutting element 20. The recess 44 has a cylindrical contour and is aligned axially along the central longitudinal axis M of the bit 10. The cutting element 20 forms opposite the cutting tip 21 from a likewise cylindrically shaped mounting portion 24 which is held in the recess 44 of the base part. The cutting element 20 is soldered to the base part 41 and thus securely and resiliently connected to the base part 41.

The wear-resistant layer 30 comprises the region of the recess 44. A comparatively thin-walled web 45 of the base part 41, which surrounds the recess 44, is thereby protected against abrasive wear. This avoids that the web 45 is abraded prematurely by vorbeischleitendes space material, which would lead to the loss of the cutting element 20 and thus premature failure of the entire chisel 10.

FIG. 3 shows a section of the in FIG. 2 As can be seen in the enlarged illustration, a recess 42 is provided around the base part 41 in a region facing the cutting element 20 into which the wear-resistant layer 30 is introduced. An outer surface 33 of the wear-resistant layer 30 thereby terminates with the base 23 and with the surface of the base part 41 extending next to the recess 42. An inner surface 32 of the wear-resistant layer 30 forms a firm connection to an outer surface 41. 1 of the base part 41 on which it is applied. An end face 31 of the wear-resistant layer 30 facing the cutting element 20 is covered by a radially aligned bearing surface 25 of the cutting element 20, which closes the base 23 towards the base part 41. The web 45 of the base part 41 is closed to the cutting element 20 through a mating surface 43. The mating surface 43 and the end face 31 of the wear-resistant layer 30 form a continuous, flat surface. This is in The embodiment shown radially arranged and is covered by the support surface 25 of the cutting element 20.

The support surface 25 of the cutting element 20 merges with the attachment section 24 via a rounded connection region 28. The rounding of the connection region 28 lies opposite a rounding surface 43. 1 of the base part 41, via which the mating surface 43 is transferred into an inner surface 44. 1 of the recess 44. The inner surface 44.1 of the recess 44 opposite an outer surface 26 of the mounting portion 24 is arranged. An end face 27 terminating the fastening section 24 lies at a distance from a bottom face 44.2 of the recess 44 of the base part 41.

Between the end face 31 of the wear-resistant layer 30 and the mating surface 43 of the base part 41 on the one side and the support surface 25 of the cutting element 20 on the opposite side, a first Lötfuge 11.1 is formed. A second solder joint 11.2 arranged between the inner surface 44.1 of the recess 44 and the outer surface 26 of the fastening section 24 of the cutting element 20 adjoins the first solder joint 11.1 continuously. Subsequent to the second solder joint 11.2, a third solder joint 11.3 is formed between the bottom surface 44.2 of the recess 44 and the end surface 27 of the fastening section 24.

The area formed by the end face 31 and the counter surface 43 is continuous and level. As a result, a first solder joint 11.1 having a uniform thickness is obtained between this surface and the opposite bearing surface 25. A uniform thickness of Lötfugen 11.1, 11.2, 11.3 is a prerequisite for a stable and resilient solder joint. The flat surface formed of the end surface 31 and the mating surface 43 may be formed by a separating or machining step or by a molding process during the application of the wear resistant layer 30, as shown in FIGS Figures 5 and 6 is explained in more detail. The advantage here is that the mating surface 43 and the end face 31 form the front end of the base part 41, so that For example, after the application of the wear-resistant layer 30 and before the soldering of the cutting element, chip-removing production methods can be applied flat over the front end of the base part 41.

Due to the formed Lötfugen 11.1, 11.2, 11.3, the cutting element 20 is securely held in the base part 41 of the chisel head 40. By carrying out the cutting element 20 with a fastening section 24 held in the recess 44 of the base part 41, thin-walled regions of the comparatively brittle cutting element 20 can be avoided. Furthermore, 24 voltage peaks are avoided by the rounded transition from the support surface 25 to the outer surface 26 of the mounting portion. Both measures significantly reduce the risk of breakage for the cutting tip 20.

The wear-resistant layer 30 is inserted into the recess 42. As a result, protruding edges are avoided in the transition of the wear-resistant layer 30 to the base 23 and the outer surface 41.1 of the base 41 outside the recess 42, whereby both the abrasive wear of the bit head 40 and the energy consumption during the use of the bit 10 is reduced. The end face 31 of the wear-resistant layer 30 is covered by the cutting element 20 and the first solder joint 11.1 filled with solder. This avoids that space material between the outer surface 41.1 of the base member 41 and the inner surface 32 of the wear-resistant layer 30 passes and this breaks off.

Between the base 23 and the outer surface 33 of the wear-resistant layer 30, an inner angle is formed in the apex of the first Lötfuge 11.1 ends. The first Lötfuge 11.1 with the comparatively soft solder material is thus placed back relative to the forming main stream of passing past Abraummaterials and thereby additionally protected against wear.

The FIGS. 4a to 4i show in side sectional view a section of the chisel head 40 with different embodiments of the wear-resistant layer 30th

In the execution according to FIG. 4a the outer surface 41.1 of the base part 41 is initially cylindrical in the region of the web 45 and then merges into a conically widening region. The outer surface 33 of the wear-resistant layer 30 is continuous conical. By this configuration it is achieved that the web 45 has a uniform thickness with a consistently comparatively high material thickness. As a result, high, acting on the cutting element 20 transverse forces can be safely intercepted. The trained wide counter surface 43 results in a secure fit of the cutting element 20 on the base part 41 and a large-area solder joint between the support surface 25 of the cutting element 20 and the counter surface 43rd

According to FIG. 4b For example, the wear-resistant layer 30 has, in its region facing the cutting element 20, its greatest layer thickness, which continuously reduces towards its opposite end. The mechanical load and thus the abrasive wear of the wear-resistant layer 30 is greatest immediately after the cutting element 20 and decreases in the direction of the collar 41.3 of the chisel head 40. The distribution of the layer thickness shown achieves an equal service life of the wear-resistant layer 30 over its entire extent. By adjusting the layer thickness in the direction of the collar 41.3, the material consumption in the production of the wear-resistant layer 30 is optimized taking into account the expected mechanical load of the wear-resistant layer 30 in the various areas along the chisel head 40.

Corresponding Figure 4c For example, the wear-resistant layer 30, in its region facing the cutting element 20, has its smallest layer thickness, which continuously increases towards its opposite end. This also makes a web 45 with a uniform, comparatively large material thickness with the already too FIG. 4a achieved advantages. The outer surface 41.1 of the base part 41 can be made cylindrical in the region of the recess 42 with a uniform distance to the central longitudinal axis M of the bit 10 and thus easy to manufacture, while the conical outer contour of the chisel head 40 is maintained.

FIG. 4d shows a variant in which the outer surface 33 of the wear-resistant layer 30 is convex. By this shaping is between the cutting element 20 and the wear-resistant layer 30 and between the wear-resistant layer 30 and adjoining the recess 42 outer surface 41.1 of the base member 41 each have a transition without protruding edges, which lead to increased abrasion achieved. At the same time, the wear-resistant layer 30 is given a high material thickness, as a result of which long service lives of the chisel head 40 and thus of the chisel 10 can be achieved. The outer surface 33 of the wearable layer 30 is aligned approximately equal to the surface profile of the cutting surface 22 of the cutting element 20, so that a uniform material flow of the spacer material results. The inner angle between the base 23 and the outer surface 22 runs comparatively pointed, so that the first Lötfuge 11.1 is clearly set back against the main material flow of the spacer material and thus protected. Also, an internal angle forms in the transition of the outer surface 33 in the outer surface 41.1 side of the recess 42, so that this connection region between the material of the wear-resistant layer 30 and the material of the base member 41 is set against the material flow of the spacer material and thus protected ,

Figure 4e shows an embodiment in which the outer surface 33 of the wear-resistant layer is designed to taper. The outer surface 41. 1 of the base part 41 is made concave in the region of the recess 42, so that the inner surface 32 of the wear-resistant layer 30 is convexly shaped. As a result, a large layer thickness of the wear-resistant layer 30 is achieved with a correspondingly long service life. The web 45 with the trained counter surface 43 is correspondingly thick-walled or large area with the associated, already too FIG. 1 performed benefits described. The conical outer surface 33 results in edge-free transitions at the edges of the wear-resistant layer 30 and thus the already described reduced abrasion and energy consumption.

According to FIG. 4f Both the inner surface 32 and the outer surface 33 of the wear-resistant layer 30 are convex. This allows the benefits of in FIG. 4d shown embodiment of a convex outer surface 33 with the Figure 4e the benefits of a convex inner surface 32 are combined.

In the embodiment according to Figure 4g the outer surface 41.1 of the base part 41 in the region of the web 45 is cylindrical and conical in connection with the web 45. The outer surface 33 of the wear-resistant layer 33 follows this shape, wherein the conical portion of the outer surface 33 is steeper than the conical portion of the outer surface 41.1. The layer thickness of the wear-resistant layer 30 is selected to be the largest in the region of the web 45 and thus the highest mechanical load of the base part 41 and decreases within the conical regions. By in the region of the web 45 cylindrically executed outer surface 33 of the wear-resistant layer 30 this is set back from the predetermined by the shape of the cutting element 20 main flow direction of the spacer material, so that the abrasion in this area against a conical or concave design of the outer surface 33 is reduced. As a result, and by the present high layer thickness of the wear-resistant layer 30, the comparatively thin-walled web is best protected against wear.

A comparable effect is shown in Figure 4h shown embodiment of the wear-resistant layer 30 with a concave outer surface 33 and a conical inner surface 32. Again, a large layer thickness in the region of the web 45 and thus in the heavily loaded, immediate vicinity of the cutting element 20 is achieved. The outer surface 33 extends in the region of the web 45 in the context of the deviation through the concave Forming approximately in the direction of the surface of the base 23. As a result, this area provides the vorbeigleitenden space material only a small attack surface, whereby the abrasion in the region of the relatively thin-walled web is kept low. In the continuing concave course of the outer surface 33, the space material is discharged away from the bit 10 to the outside, thereby protecting the uncoated area of the bit head 40. Due to the conical shape of the coated outer surface 41.1 of the base part 41, the material thickness of the web 45 increases towards its base, so that even high, registered via the cutting element 20 lateral forces without damaging the web 45 can be intercepted.

FIG. 4i shows a section of the chisel head 40 with a wear-resistant layer 30, the outer surface 33 has alternately concave and convex portion. In the concave regions, the spacer material may settle, so that the outer material sliding past it, at least in the concave regions, is not in direct contact with the outer surface 33 of the wear-resistant layer 30. By this simple measure, the abrasion of the wear-resistant layer 30 can be significantly reduced.

FIG. 5 shows in a further sectional side view a section of the chisel head 40 with an auxiliary tool 60. The chisel head 40 is still present as a semi-finished product without the soldered cutting element 20. FIG. 5 shows a possibility for coating the base part 41 of the chisel head 40 with the wear-resistant layer 30, so that a continuous, flat surface between the end face 31 of the wear-resistant layer 30 and the mating surface 43 of the base part 41 is formed.

Shown is a bit head 40 with a wear resistant layer 30 having a uniform layer thickness. However, the method can be used for any other embodiment of the wear-resistant layer 30, as exemplified in the FIGS. 4a to 4i are shown.

The auxiliary tool 60 is formed from a base 61, in the center of which an axially aligned positioning pin 63 is arranged. The diameter of the base 61 is selected so that it projects radially beyond the wear-resistant layer 30. The positioning pin 63 is designed such that it can be inserted into the recess 44 of the chisel head 40 with little lateral play. It ends spaced by a gap 44.3 before the completion of the recess 44. The auxiliary tool 60 is made in the present embodiment of a metal, preferably made of copper.

Prior to the application of the wear-resistant layer 30, the auxiliary tool 60 is so determined with its positioning pin 63 in the recess 44 that it rests with a running around the positioning pin 63 forming contact surface 62 on the mating surface 43 of the base member 41. Subsequently, the wear-resistant layer 30 is introduced into the recess 42. The wear-resistant layer 30 is applied by means of a welding process in such a way that it bears against the abutment surface 62 of the base 61. This forms an end face 31 of the wear-resistant layer 30, which merges evenly and continuously into the mating surface 43 of the base part 41. After the coating process, the auxiliary tool 60 is removed.

By appropriate structuring of the shaping surface 63, the end face 31 of the wear-resistant layer 30 can be smooth or provided with a predetermined roughness or with another structure, for example with grooves. Advantageously, a roughness in a range of Rz = 4μm to 280μm or groove depths in a range of 2μm to 500μm is provided. The surface structure of the end face 31 can thus be optimized for a good flow of the solder.

FIG. 6 shows in a further sectional side view a section of a chisel head 40 in an extended to its final dimension in the direction of the cutting element 20 size. Again, this is a semi-finished product in which the cutting element 20 is not yet applied. The later final dimension of the base part 41 is marked by a dividing line T. The base 41 is the length of a supernatant 12 extended. The recess 42 of the base part 41 continues on the projection 12. Also, the axial recess 44 is inserted in the base part 41 and the supernatant 12. The projection 12 ends in a radially aligned end surface 13.

Shown is a bit head 40 with a wear resistant layer 30 having a uniform layer thickness. However, the method can be used for any other embodiment of the wear-resistant layer 30, as exemplified in the FIGS. 4a to 4i are shown.

The wear-resistant layer 30 is introduced by a welding process in the recess 42 of the extended chisel head 40. The illustration shows schematically the rough outer surface 33 of the wear-resistant layer 30 due to the welding process.

In the illustrated embodiment, the wear-resistant layer 30 opposite the end face 13 on one side of the supernatant 12 forms a projecting bead 34 and on the opposite side of a recessed Bulge off. Both are for the formation of a resilient solder joint with a uniform Lötfuge 11.1, 11.2, 11.2 to a rectilinear surface, as given by the support surface 25 of the cutting element 20, unsuitable.

To form the required flat surface between the mating surface 43 of the base part 41 and the end face 31 of the wear-resistant layer 30, the overhang 12 is separated along the dividing line T from the base part 41. This can be done by a separation process, for example by sawing, or a machining production process, such as milling. Also, the separation surface can be further processed in a subsequent processing step. Thus, a defined roughness of the parting surface can be produced or grooves or other structures can be incorporated into the parting surface, which the Improve flow behavior of a solder used for soldering the cutting element 20. The roughness can be adjusted to a range between RZ = 4 μm to 280 μm or grooves with a groove depth in a range between 2 μm and 500 μm can be introduced.

Both after that too FIG. 5 as well as too FIG. 6 described manufacturing process, a formed from the mating surface 43 and the end face 31, continuous and flat surface is obtained, against which the support surface 25 of the cutting element 20 can be positioned and soldered. It forms a uniform and thus resilient first Lötfuge 11.1, as in the FIGS. 1 to 4 is shown.

FIG. 7 shows a side sectional view of a section of a projecting in the axial direction wear-resistant layer 30th

The cutting element 20 is formed from the cutting tip 21, the concave-shaped cutting surface 22 and the base 23 in the embodiment shown. The base 23 forms a base part 41 of the chisel head 40 oriented towards, continuous and flat support surface 25.

The wear-resistant layer 30 is introduced into the circumferential recess 41 arranged around the recess 44. In this case, a radially inwardly located part of the wear-resistant layer closes toward the cutting element 20 with the mating surface 43 of the base part 41 and forms the end face 31 there. The cutting element 20 rests on the mating surface 43 and the end face 31 via a solder connection with its bearing surface 25. It covers a centering notch 43.2 introduced along the central longitudinal axis M of the chisel head 40 into the mating surface 43.

Laterally of the end face 31 is the wear-resistant layer 30 in the axial direction via the mating surface 43 and the end face 31 via. It thereby forms a centering collar 36, which encloses the base 23 of the cutting element 20 in its region facing the base part 41. The wear-resistant layer 30 covers Thus, a surface adjacent to the support surface 25 of the cutting element 29 from 20. Between the surface portion 29 and the centering collar 36, a fourth solder joint 11.4 is formed.

The wear-resistant layer 30 forms, together with the mating surface 43 of the base part 41, a cup-shaped receptacle 46, in which the cutting element 20 is soldered with its base 23. By the cup-shaped receptacle 46, the cutting element 20 is correctly aligned during the soldering process and held in position. Between the mating surface 43, the end face 31 and the centering collar 36 on one side and the cutting element 20 on the other side, a solder joint is formed. The cutting element 20 is thus securely connected to the base part 41 of the chisel head 40. The section of the solder joint formed between the bearing surface 25 and the mating surface 43 or the end surface 31 is arranged protected by the peripheral centering collar 36 of the wear-resistant layer 30. This results in a durable, wear-protected composite between the cutting tip 20 and the base 41st

FIG. 8 shows a side sectional view of a section of a chisel head 40 in a further embodiment of a projecting in the axial direction wear-resistant layer 30th

The cutting element 20 substantially corresponds to the in FIG. 7 illustrated cutting element 20, wherein on the base 23 on the base part 41 of the chisel head 40 facing region, a base projection 23.1 is formed. The base projection 23.1 has a conically tapering to the base portion 41 towards cross-section.

The centering collar 36 of the wear-resistant layer 30 follows the conical surface portion 29 of the base 23, which is arranged in the region of the base extension 23.1. The base extension 23.1 is thus covered by the wear-resistant layer 30 as the section of the cutting element 20 facing the base part 41.

Again, the base projection 23.1 and the counter surface 43 of the base part form a cup-shaped receptacle 46, in which the cutting element 20 is soldered. The Lötfugenbereich formed between the support surface 25 and the mating surface is thus circumferentially surrounded by the wear-resistant layer 30 and thereby protected. By the fourth Lötfuge 11.4 the formed soldering surface between the base part 41 and the cutting tip 20 is increased, so that a firm connection between the cutting tip 20 and the base part 41 is formed.

FIG. 9 shows in a sectional side view a section of the chisel head 40 with an auxiliary tool 60th

The base part 41 and the wear-resistant layer 30 of the chisel head 40 show the same shape as before FIG. 7 , but there with inserted cutting element 20, described.

The auxiliary tool 60 is formed from a base 61, to which a projection 64 is formed. The auxiliary tool 60 is rotationally symmetrical about the central longitudinal axis M. The projection 64 has a smaller diameter than the base 61. The projection 64 rests with its contact surface 62 on the mating surface 43 of the base part 41 and on the end face 31 of the wear-resistant layer 31. In the middle of the contact surface 62, a centering mandrel 64.1 is formed, which engages in the centering notch 43.2 of the base part 41.

The auxiliary tool 60 is placed before the application of the wear-resistant layer 30 with its contact surface 62 on the mating surface 43 of the base part 41. In this case, the centering mandrel 64.1 engages in the centering notch 43.2, so that the auxiliary tool 60 is aligned with respect to the base part 41. Subsequently, the wear-resistant layer 30 is applied, preferably by welding. The wear-resistant layer 30 is applied in such a way that it fills the recess 44. On the side of the auxiliary tool 60, the wear-resistant layer 30 is up to the over the mating surface 43 of the base part 41 projecting surface of the abutment surface 62 of the auxiliary tool 60 and on the outer surface of the projection 64 of Auxiliary tool 60 applied. Thus, the end face 31 and the centering collar 36 are formed, which projects axially beyond the counter surface 43 and, in the present exemplary embodiment, over the end face 31 of the wear-resistant layer 30. The centering collar 36 is limited by the base 61 of the auxiliary tool 60.

After the coating process, the auxiliary tool 60 is removed. The stepped-shaped wear-resistant layer 30 remains as an impression of the auxiliary tool 60. The cutting element 20, which is formed in the cup-shaped receptacle 46 thus formed, can be soldered in FIG. 7 is shown.

The contour of the auxiliary tool 60 is designed so that it follows the contour of the intended cutting element 20. For the production of in FIG. 8 illustrated chisel 10 may be provided, for example, an auxiliary tool 60, the neck 64, starting from the base 61, tapers conically. As a result, a centering collar 36 corresponding to the in FIG. 8 obtained, which follows the conical shape of the base extension 23.1 of the cutting element 20 shown there.

That in the Figures 5 and 9 The auxiliary tool shown is preferably made of a material which does not form a metallurgical bond to the wear-resistant layer. The auxiliary tool may be made of copper, for example.

To produce the cup-shaped receptacle 46, according to an alternative manufacturing method, an extended base part 41 may also first be coated and then shortened, as is the case FIG. 6 is described. Subsequently, the cup-shaped receptacle 46 can be introduced into the base part 41 and the wear-resistant layer 30 by a subsequent processing step, in particular by milling or drilling.

Claims (16)

1. A pick (10), in particular round-shank pick, comprising a pick head (40) and a pick shank (50), wherein the pick head (40) is formed at least from a base part (41) and a cutting element (20) made of a hard material, in particular of hard metal, connected to the base part (41),
   wherein the base part (41), following the cutting element (20), has a wear-resistant layer (30) on the outer surface (41.1) thereof, said wear-resistant layer covering at least one section of the outer surface (41.1) of the base part (41) facing the cutting element (20), wherein an end surface (31) of the wear-resistant layer (30) facing the cutting element (20) is covered by the cutting element (20),
   wherein the base part (41) has an axially oriented recess (44) for receiving a fastening section (24) of the cutting element (20),
   wherein circumferentially with respect to the recess (44), the base part (41) has a mating surface (43) facing the cutting element (20),
   wherein the mating surface (43) and the end surface (31) of the wear-resistant layer (30) form a continuous planar surface, or the end surface (31) of the wear-resistant layer is brought to the mating surface (43),
   and wherein the cutting element (20), circumferentially with respect to the fastening section (24) thereof, forms a supporting surface (25),
   characterised in that
   the supporting surface (25) covers the mating surface (43) and the end surface (31) at least in regions,
   and that a first soldered joint (11.1) is configured between the supporting surface (25) and the continuous surface formed by the mating surface (43) and the end surface (31).
2. The pick (10) according to claim 1,
   characterised in that
   the wear-resistant layer (30) is received in a depression (42) of the base part (41).
3. The pick (10) according to claim 1 or 2,
   characterised in that
   the mating surface (43) and the end surface (31) are designed as separating surfaces created in a process step, in particular as cut surfaces or as ground surfaces or as milled surfaces, or in that the end surface (31) is designed as an impression surface of a base (61) of an auxiliary tool (70), said base lying on the mating surface (43) and protruding radially beyond the mating surface (43), said impression surface formed during an application process, in particular during a welding process, of the wear-resistant layer (30).
4. The pick (10) according to one of claims 1 through 3,
   characterised in that
   the mating surface (43) and/or the end surface (31) are designed as smooth surfaces or as surfaces having a predetermined roughness in a range of Rz = 4 µm to Rz = 280 µm or as surfaces comprising introduced grooves which have a groove depth in a range of 2 µm to 500 µm.
5. The pick (10) according to one of claims 1 through 4,
   characterised in that
   a second soldered joint (11.2) is configured between an outer surface (26) of the fastening section (24) and an inner surface (44.1) of the recess (44) and/or that a third soldered joint (11.3) is configured between an end surface (27) of the fastening section (24) and a bottom surface (44.2) of the recess (44).
6. The pick (10) according to one of claims 1 through 5,
   characterised in that
   the wear-resistant layer (30) encloses in axial orientation at least the section of the pick head (40) in which the recess (44) is introduced.
7. The pick (10) according to one of claims 1 through 6,
   characterised in that
   the wear-resistant layer (30) has a uniform layer thickness or that the wear-resistant layer (30) has a varying layer thickness.
8. The pick (10) according to claim 7,
   characterised in that
   the layer thickness of the wear-resistant layer (30), proceeding from the end surface (31) thereof facing the cutting element (20), decreases in the direction of the end thereof facing the pick shank (50), or that the layer thickness of the wear-resistant layer (30), proceeding from the end surface (31) thereof facing the cutting element (20), increases in the direction of the end thereof facing the pick shank (50).
9. The pick (10) according to one of claims 1 to 8,
   characterised in that an outer surface (33) of the wear-resistant layer (30) is convexly curved along the longitudinal extension thereof, or that the outer surface (33) is concavely curved along the longitudinal extension thereof, or that the outer surface (33) has concavely and convexly curved sections along the longitudinal extension thereof.
10. The pick (10) according to one of claims 1 to 9,
    characterised in that
    an internal angle is configured between the surface of the cutting element (20) and the outer surface (33) of the wear-resistant layer (30) in the transition thereof.
11. The pick (10) according to one of claims 1 to 10,
    characterised in that
    the cutting element (20) with the supporting surface (25) rests directly or indirectly at least in regions on the base part (41), and
    in that the wear-resistant layer (30) covers at least one surface section (29) of the cutting element (20) which adjoins the supporting surface (25).
12. The pick (10) according to one of claims 1 to 11,
    characterised in that
    a soldered joint (fourth soldered joint, 11.4) is configured between the wear-resistant layer (30) and the surface section (29) of the cutting element (20).
13. The pick (10) according to one of claims 1 through 12,
    characterised in that
    the wear-resistant layer (30) protrudes beyond the mating surface (43) in the direction of a central longitudinal axis (M) of the pick head (40) and/or that the wear-resistant layer (30) and the mating surface (43) form a bowl-shaped receptacle (46) for the cutting element (20).
14. A method for coating at least one section of an outer surface (41.1) of a pick head (40) of a pick (10) according to one of claims 1 through 13, in particular a round-shank pick, with a wear-resistant layer (30),
    wherein an auxiliary tool (60) is fixed to the base part (41) of the pick head (40) in such a way that said auxiliary tool rests on the mating surface (43) with at least a section of a contact surface (62),
    wherein in a first method step the outer surface (41.1) is coated with the wear-resistant layer (30),
    wherein in a second method step, a cutting element (20) is soldered onto a surface of the wear-resistant layer (30) facing the cutting element (20) and a front mating surface (43) of a base part (41) of the pick head (40),
    and wherein the auxiliary tool (60) is subsequently removed.
15. The method according to claim 15,
    characterised in that
    the wear-resistant layer (30) is applied to the outer surface (41.1) of the pick (10) in such a way that said wear-resistant layer bears with the end surface (31) thereof against at least a section of the contact surface (62) of the auxiliary tool (60) and/or against a surface region (65) of the auxiliary tool (60) adjoining the supporting surface (62) with a spatial orientation deviating from the bearing surface (62).
16. The method according to claim 14 or 15,
    characterised in that
    a layer of a hard material, in particular of hard metal, and/or an iron alloy and/or a nickel alloy and/or a cobalt alloy and/or a titanium alloy and/or tungsten carbide and/or titanium carbide is applied as the wear-resistant layer (30).

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