EP3563000A1

EP3563000A1 - Tool combination having a chisel holder and two chisels

Info

Publication number: EP3563000A1
Application number: EP17818062.6A
Authority: EP
Inventors: Karsten Buhr; Andreas Jost; Thomas Lehnert; Sebastian Hofrath; Martin Lenz
Original assignee: Wirtgen GmbH
Current assignee: Wirtgen GmbH
Priority date: 2016-12-30
Filing date: 2017-11-30
Publication date: 2019-11-06
Anticipated expiration: 2037-11-30
Also published as: WO2018121956A1; US10968577B2; CN108265608A; DE102016125921A1; CN208440958U; US20190316304A1; CN108265608B; TW201822979A; EP3563000B1

Abstract

The invention relates to a tool combination consisting of a chisel holder, which can be fastened to a milling drum of a soil tillage machine, and at least one leading and one trailing chisel, which are retained on the chisel holder, wherein the trailing chisel is arranged after the leading chisel, based on a working movement of the tool combination in use in the soil tillage machine, and wherein each chisel has a chisel tip having a cutter. According to the invention the trailing chisel tip of the trailing chisel has, at least in some areas, a greater hardness than the leading chisel tip of the leading chisel. Thus stoppage times of the soil tillage machine for maintenance can be reduced and the loss of chisels can at least be decreased.

Description

Tool combination with a chisel holder and two chisels

The invention relates to a Werkzeugkonnbination of a chisel holder, which is fastened to a milling drum of a tillage machine, and at least one leading and a trailing chisel, which are held on the chisel holder, wherein the trailing chisel, based on a working movement of the tool combination when used in the Soil cultivation machine, is arranged behind the leading chisel and wherein each chisel has a chisel tip with a cutting edge.

Such a tool combination is known from US 4,342,486. The document shows a milling drum with a designed to accommodate two milling bits chisel holder. The chisels are arranged one after the other in the direction of rotation of the milling drum. In this case, a front chisel in the direction of rotation is arranged so that its chisel tip is moved over a larger radius about the axis of rotation of the milling drum than the chisel tip of the trailing second chisel. The removal of the soil material takes place first by the engagement of the first bit. If the first chisel breaks, the second chisel takes over the processing function. The second bit thus assumes a backup function, which allows further milling even if damage or loss of the first bit and at the same time causes protection of the bit holder and the milling drum. The chisels are aligned parallel to each other. They are interchangeably connected to the bit holder, so that they can be replaced with appropriate wear. In this case, the same chisel or chisel in different lengths, but with the same holding mechanism for attachment to the bit holder and the same structure of the chisel tips, can be provided.

The document US 5,582,468 describes a bit holder for a tillage machine, which can be fixed to a milling drum. The bit holder has two holes for receiving two bits. The chisels are arranged one behind the other in the direction of rotation of the milling drum. The holes are aligned obliquely to each of a radial line of the milling drum and pointing in the direction of rotation, so that the chisel impinge on the substrate to be processed at a desired angle. The holes are further arranged at different radii, wherein the further forward in the direction of rotation hole is located at a smaller radius than the rear hole. As a result, a tip of a bit received in the rear bore is moved at a greater radius about the axis of rotation of the milling drum than a tip of a similar front bit. The rear chisel takes over the essential part of the material removal. In case of a fracture of the rear chisel, the material removal shifts towards the front chisel. The front chisel is arranged to shield the bore and the outer edge of the rear bore in the direction of movement of the chisels. This protects the rear bit holder from excessive abrasive wear, even if the rear bit is broken or lost. The bits are interchangeably connected to the bit holder so that they can be replaced in case of advanced wear or damage.

In WO 2013/064433 a chisel tip for a chisel is described, as it can be used for a tillage machine. The tip indicates Substrate, which carries a polycrystalline diamond (PCD). The polycrystalline diamond forms the cutting edge of the chisel tip. Due to the high hardness of the polycrystalline diamond, the chisel has very little wear. As shown in the application, in such an arrangement, the bit holder wears faster than the bit itself. As a result, a bit receptacle in which the bit is held can be exposed and the bit lost. Furthermore, it may happen that a used chisel can not be installed in a new bit holder due to its, albeit small, wear in the connection area. Because of the diamond equipment, the chisels are very expensive to manufacture. With lost or no longer usable chisels, the operating costs of the soil tillage machine increase significantly.

It is an object of the invention to provide a tool for a tillage machine, which allows for long maintenance intervals cost-effective operation of the tillage machine.

The object of the invention is achieved in that the trailing chisel tip of the trailing chisel at least partially has a greater hardness than the leading chisel tip of the leading chisel. The trailing chisel tip follows in a milling process the track of the leading chisel tip. As a result, the trailing chisel tip is less stressed and is thus exposed to less wear than the leading chisel tip. Due to the greater hardness of the trailing chisel tip, combined with the reduced mechanical load, the service life of the trailing chisel can be extended so that it no longer needs to be exchanged, or only very rarely. The maintenance intervals are thus based solely on the wear of the leading chisel. Furthermore, the leading chisel protects the area in which the trailing chisel is held on the chisel holder. Thus, the wear of the chisel holder is significantly reduced in the joining region between the trailing chisel and the chisel holder. A loss of trailing chisel can be avoided. Due to the less frequently required maintenance and avoidance the loss of trailing chisels can significantly reduce the operating costs of the tillage machine.

According to a particularly preferred embodiment variant of the invention it can be provided that the trailing chisel tip is at least partially made of a superhard material, in particular a diamond material, a diamond-reinforced material, a silicon carbide material, cubic boron nitride or compounds of at least two of the aforementioned materials , By using such a superhard material for at least partial formation of the trailing chisel tip, the service life of the trailing chisel can be extended to the service life of the chisel holder. An exchange of the trailing bit is therefore no longer required and the maintenance intervals of the chisel are based solely on the wear of the leading chisel. With the use of diamond materials or diamond-reinforced materials extremely resistant chisel can be provided, which have a life in the range of life of the chisel holder even with relatively high mechanical load of the trailing chisel. Chisel tips, which are at least partially formed of a silicon carbide material or cubic boron nitride, however, are cheaper to produce. In this case, they have, for example, for arrangements and applications in which the trailing chisel tip is exposed to a lower mechanical stress, adapted to the service life of the chisel holder life expectancy. By appropriate connections of the materials mentioned, the resistance of the trailing bit can be adapted to the expected load.

A very high mechanical load capacity of the trailing bit can be obtained by at least a proportion of the diamond material as a monocrystalline diamond or as a polycrystalline diamond or as a chemically deposited diamond or as a physically deposited diamond or as a natural diamond or as an infiltrated diamond or as a diamond layer or as successive diamond layers or as a thermally stable diamond or as silicon-bonded diamond is formed. Through the use of monocrystalline diamonds, bit tips with the highest wear resistance can be obtained. When using polycrystalline diamonds or chemically or physically deposited diamonds, it is possible to achieve degrees of hardness of the bit tips which at least approximately corresponds to the hardness of monocrystalline diamonds. In this case, polycrystalline diamonds or chemically or physically deposited diamonds compared to monocrystalline diamonds cheaper to provide. Through infiltrated diamonds, the properties of the chisel tip can be adjusted within a given framework to the expected requirements and loads. By means of diamond layers, the amount of diamond required can be adapted to the actual requirements by adjusting the layer thicknesses and thus the production costs can be reduced. In this case, the properties of the diamond layers can be adapted to the respective requirements by successive diamond layers. Thus, for example, an outer diamond layer can be made very hard and thus mechanically resilient, while an inner diamond layer is adapted for a firm and permanent connection to a substrate as part of the bit tip on which the diamond layers are deposited. Thermally stable diamonds allow manufacturing processes for the bit or the bit tip, which require high temperatures, such as soldering processes. For silicon-bonded diamond, small diamond segments are connected by silicon. The small diamond segments are comparatively inexpensive to produce and can be present for example as monocrystals. Silicon-bonded diamond can be easily adapted to the desired contour of the trailing chisel tip and its cutting edge.

A high loadable and at the same time easily and mechanically firmly connectable with another workpiece chisel tip can be obtained by the trailing chisel tip of a base support of a hard material, preferably made of hard metal, which is facing the trailing edge facing out of the superhard material , The trailing edge is thus formed by the superhard material. The one from the hard material existing base supports can be soldered to another section of the trailing bit, such as a chisel head.

A cost-effective production of the trailing bit can be achieved in that the superhard material is formed as a layer. The shape of the trailing chisel tip or the trailing edge can then be predetermined, for example, by the shape of a base support. On this, the superhard material is applied as a layer, whereby a very hard cutting edge is formed.

According to a preferred embodiment variant of the invention it can be provided that the trailing bit is axially and fixedly connected in its circumferential direction with the bit holder and / or that the leading bit is held axially and rotatably connected in its circumferential direction with the bit holder. The non-rotatable attachment of the trailing bit reduces vibrations during tool engagement. Such vibrations can lead to breakage of superhard and thus brittle material. Due to the rotatable mounting of the leading chisel, it is rotated about its longitudinal axis upon engagement with the soil material to be removed. This results in a uniform, circumferential wear of the chisel tip and / or the chisel head. The service life of the leading chisel can be increased. Furthermore, self-sharpening of the leading bit occurs due to the uniform circumferential wear. As a result, the leading chisel relatively easily penetrate into the material to be removed, whereby the energy costs for operation of the tillage machine decline.

Due to the at least partially greater hardness of the trailing chisel tip, especially in a trailing chisel tip, which is at least partially made of a superhard material, as well as by the lower compared to the leading chisel tip mechanical load on the trailing chisel tip, over a long time a virtually unchanged cutting engagement trailing chisel tip can be achieved. The life expectancy of trailing chisel is thus in the range of life expectancy of the chisel holder. The life expectancy of the leading bit is lower than that of the trailing bit and chisel holder due to its lower hardness and higher mechanical stress during use. Therefore, it can be provided that the trailing bit is not destructively interchangeable connected to the bit holder and / or that the leading bit is replaceably connected to the bit holder. The trailing chisel thus remains connected to it over the entire service life of the chisel holder. The leading chisel, which is much cheaper to produce than the trailing chisel, can be replaced when it reaches its wear limit.

According to the invention it can be provided that the trailing bit is formed from the trailing chisel tip, which is not detachably connected directly to the bit holder, in particular soldered, and / or that the trailing bit at least from the trailing chisel tip and thus indirectly or directly connected shaft is formed and that the shaft is held in a trailing bit holder of the bit holder, preferably by means of a cohesive, a frictional or a positive connection. A trailing chisel formed only from the trailing chisel tip can be produced comparatively inexpensively. In this case, the trailing chisel from the base support of a hard material, preferably made of hard metal, be formed, which is covered to the trailing edge facing out of the superhard material. The base support may be connected directly to the bit carrier. In this case, a reliable and cost-effective connection can be made, for example by soldering. The base support is dimensioned such that it can be introduced into a production unit for connection to a superhard material. The chisel tip made in this way can be connected directly to the bit carrier. It is also possible to connect the bit tip directly or indirectly, for example via a arranged between the bit tip and the shaft chisel head with a shaft. The shaft can then in the trailing chisel with the Chisel carrier to be connected. The connection between the shaft and the bit receptacle can be cohesively, for example via soldering or gluing done. Also possible are non-positive connections. Such a frictional connection can be made for example by cold stretching or shrinking of the shaft in the trailing bit holder. The shaft is made with an oversize, cooled and introduced into the trailing bit holder. When warming up, it expands and forms a firm connection to the trailing chisel holder. Accordingly, the connection can be made by shrinking, wherein the bit holder is warmed up and the oversized shaft of the trailing bit is inserted into the extended by the elevated temperature, trailing bit holder. It is also conceivable to provide a screw connection between the shaft and the bit holder.

A uniform milling pattern can be obtained by the trailing bit being designed and arranged to rework a milling performed by the leading bit. By post-processing the milling by the trailing chisel, the milling pattern, regardless of the state of wear of the leading chisel remains. This applies in particular to trailing chisels, each with a trailing chisel tip equipped with a super-hard material, which guarantee an almost unchanged cutting engagement over a long period of time.

A uniform milling pattern on one side and a comparatively low mechanical load and thus a low wear of the trailing bit on the other side can be achieved by designing and arranging the trailing bit to remove a smaller chip volume from the leading bit To cut material.

In order to rework the milling of the leading bit by the trailing bit, it can be provided that the leading bit and the trailing bit are formed and arranged on the bit holder, in the case of a tool combination mounted on a milling drum, the leading edge of the leading chisel tip of the leading chisel is arranged at a larger radius relative to an axis of rotation of the milling drum than the trailing edge of the trailing chisel tip of the trailing chisel or the two cutting edges are arranged on substantially equal radii , Substantially equal here means in particular to ± 3 mm equal radii. The trailing chisel carries in this arrangement, the chisel tips a significantly smaller chip volume than the leading chisel. As a result, a uniform removal of the substrate to be processed can be achieved, resulting in a very uniform and homogeneous milling pattern. This is particularly desirable in fine milling, in which, for example, an upper layer of a roadway is removed.

The leading chisel penetrates first into the substrate to be processed, followed by the trailing chisel. The tracks on which the leading cutting edge and the trailing cutting edge are guided by the material to be processed depend on at least the milling depth, the rotational speed of the milling drum and the feed rate of the soil cultivation machine. The volume of material removed by each bit thus depends at least on these machine parameters and on the relative location of the trailing edge of the trailing bit to the leading edge of the leading bit. In order to obtain the desired uniform milling pattern, it can be provided that the spacing of the cutting edges of the bit tips to one another and the radii on which the cutting edges of the bit tips are arranged in a tool combination mounted on a milling drum are selected such that at a predetermined feed rate Soil cultivation machine and a predetermined speed of the milling drum, the trailing chisel has a predetermined depth of penetration into the material to be milled. Due to the coordinated machine parameters and arrangement of the cutting can be achieved that the leading chisel cuts a larger volume than the trailing chisel. Thus, for example, the leading chisel for roughing and the trailing chisel for finishing be provided. By the leading chisel while the largest part of the substrate to be machined is removed, while the desired milling pattern is produced by the trailing chisel.

An adaptation to common machine parameters of the tillage machine can be achieved in that the distance between the cutting edge of the leading chisel tip and the trailing chisel tip between 45mnn and 75mnn, preferably between 50mnn and 60mnn, more preferably 54mnn, and / or that the radius on the in a mounted on a milling drum tool combination, the trailing edge of the trailing chisel tip is disposed between 1 mm and 7mm, preferably between 2mm and 5mm, more preferably 3mm, is chosen smaller than the radius on which the leading edge of the leading chisel tip is arranged.

A conceivable variant of the invention is such that the trailing bit is aligned at a smaller angle to a running through the trailing edge radial line than the leading bit against a running through the leading edge radial line, preferably that the trailing bit in an angle between 25 ° and 35 ° and the leading chisel are aligned at an angle between 35 ° and 45 ° relative to the respectively associated radial line. Due to the larger angle of incidence of the leading chisel, in particular between 35 ° and 45 °, a self-sharpening of the leading chisel is achieved in all common milling tasks. Due to the smaller angle of incidence of the trailing chisel, in particular in a range between 25 ° and 35 °, this is aligned in the direction of the resulting force, in particular during fine milling.

According to a particularly preferred embodiment variant of the invention, it may be provided that a joining zone formed between the trailing bit and the bit holder is at least partially covered by the leading bit along the working movement of the tool combination. By the leading chisel thus the worn soil material the passing between the trailing chisel and the bit holder joining zone passes. This avoids excessive wear of the bit holder in the region of the joining zone. A loss of the trailing chisel can thus be prevented.

The mechanical load of the optionally not non-destructively replaceable, trailing bit can be kept low, that the leading chisel transversely to the working movement of the tool combination on the trailing chisel. The soil material removed by the leading chisel is thus guided past the trailing chisel on the side. As a result, the service life of the trailing bit can be significantly increased. Preferably, the leading chisel is on both sides of the trailing chisel over.

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

Fig. 1 in a schematic representation and side view of a

Soil preparation machine in the form of a road milling machine,

Fig. 2 is a side view of a tool combination with a

Chisel holder, a leading chisel and a first trailing chisel,

3 is a side view of the tool combination shown in Fig. 2, mounted on a base part,

Fig. 4 in a side view of a tool combination with a

Chisel holder, a leading chisel and a second trailing chisel,

Fig. 5, the tool combination shown in Fig. 4 in a plan view and Fig. 6, the tool combination shown in Figures 4 and 5 in a side sectional view.

Figure 1 shows a schematic representation and side view of a soil working machine 10 in the form of a road milling machine. A machine frame 12 is about four lifting columns 16.1, 16.2 adjustable in height of trolleys 1 1 .1, 1 1 .2, for example, chain drives worn. The tilling machine 10 can be operated, starting from a control station 13, via a control 17 arranged in the control station 13. Boxes in a concealed arranged milling a likewise concealed arranged and dashed lines in the illustration milling drum 15 is rotatably mounted about a rotation axis 15.1. A conveyor 14 serves to remove the milled material.

In use, the machine frame 12 is moved with an input via the controller 17 feed speed over the substrate to be processed. In this case, carry on the rotating milling drum 15 arranged and shown in Figures 2 to 6 chisel 20, 30, 31 from the ground. The height position and the rotational speed of the milling drum 15 can be adjusted by the controller 17. About the height position of the milling drum 15, the milling depth is set. The height position of the milling drum can be done depending on the machine type on the height-adjustable lifting columns 16.1, 16.2. Alternatively, the milling drum 15 relative to the machine frame 12 in height adjustable.

FIG. 2 shows a side view of a tool combination 50 with a bit holder 40, a leading chisel 20 and a first trailing chisel 30. The leading chisel 20 has a chisel head 21 and a chisel shaft 24 integrally formed thereon and shown in FIG. The chisel head 21 carries a leading chisel tip 22, consisting of a hard material, such as carbide. At the end, the leading chisel tip 22 forms a leading edge 23. The leading chisel tip 22 is usually soldered to the chisel head 21 along a contact surface. In the chisel head 21 is a receptacle 21 .2 incorporated, in which the chisel tip 22 is inserted and soldered.

As shown in Figure 6, the drill collar 24 carries a longitudinally slotted, cylindrical clamping sleeve 25. This is captive in the direction of the longitudinal extension of the leading bit 22, but freely rotatable in the circumferential direction, held on the drill collar 24. In the area between the clamping sleeve 25 and the chisel head 21, a wear protection disk 26 is arranged. In the mounted state, the wear plate 26 is supported on a mating surface of the bit holder 40 and the bit holder 40 turned away on the underside of the bit head 21, which is widened in this area by a collar 21 .1 in diameter from.

The bit holder 40 is provided with a leading lug 41, in which, as shown in Figure 6, a leading chisel holder 42 is incorporated in the form of a cylindrical bore. In this leading chisel holder 42, the clamping sleeve 25 is clamped with its outer periphery on the bore inner wall. The leading chisel receptacle 42 opens into a Austreiböffnung 47. Through this, for the purpose of disassembly of the leading chisel 20 a Austreibdorn (not shown) are introduced. This acts on the end of the drill collar 24 in such a way that, overcoming the clamping force of the clamping sleeve 25, the leading chisel 20 is pushed out of the leading chisel holder 42.

The leading lug 41 is integrally formed on a base 43 of the chisel holder 40. Laterally offset and opposite to the leading approach 41, a plug-in projection 44 is integrally connected to the base 43. The plug-in projection 44 can be inserted into a plug-in receptacle of a base part 60 shown in FIG. 3 and clamped there by means of a clamping screw, not shown. For this purpose, the insertion lug 44 has a clamping surface 44.1, shown in FIG. 2, on which the clamping screw engages. Laterally from the plug-in projection 44, the base part 43 contact surfaces 43.1, with which it is mounted under the action of force of the clamping screw is pressed against the base part 60 shown in Figure 3. The base part 60 itself is welded on its underside 61 onto a milling roller tube of the milling drum 15 indicated in FIG. In the present embodiment, four contact surfaces 43.1 are provided on the base part 43. These are two rear abutment surfaces 43. 1, which are arranged at least in regions behind the insertion lug 44. Furthermore, two front abutment surfaces 43.1 are used, which are arranged at least partially in front of the insertion lug 44. The two rear abutment surfaces 43.1 are at an angle to each other. Likewise, the two front abutment surfaces 43.1 are at an angle to each other. The rear abutment surfaces and the front abutment surfaces 43.1 each form a contact surface pair. In this case, the contact surfaces 43.1 of a contact surface pair diverge starting from the insertion projection side 44 in the direction of the machining side defined by the chisels 20, 30. In addition, the front abutment surfaces 43.1 are at an angle to the rear abutment surfaces 43.1

As an alternative to the four abutment surfaces 43.1, which can be made pyramid-shaped in particular, it is conceivable to use three abutment surfaces 43.1, which are at an angle to one another and are also employed in a pyramid-like manner to one another. It can be provided that in the direction of movement at least partially behind the plug projection 44, a contact surface 43.1 and at least partially in the direction of movement before the insertion lug 44 two contact surfaces 43.1 are provided in the direction of movement. Conversely, it is also conceivable that in the area behind the plug-in approach 44 at least partially two mutually angled abutment surfaces 43.1 and at least partially in the direction of movement before the insertion projection 44 a contact surface 43.1 is provided.

The contact surfaces 43.1 serve to support the chisel holder 50 on the base part 60. Accordingly, the base part 60 corresponding support surfaces on which the contact surfaces 43.1 of the chisel holder 50 put on. By the rotation of the Fräswälze 15 and the feed of the soil working machine 10, the tool combination 50 is moved in accordance with a direction indicated by an arrow working movement 76. Based on this working movement 76, a first trailing shoulder 45 is integrally formed on the base 43 of the bit holder 40 behind the leading approach 41. The leading tab 41 and the first trailing tab 45 are joined together along their facing sides. At its end facing away from the base 43, the first trailing projection 45 forms a first front side 45.1. In this first front side 45.1 a Lötausnehmung 45.2 is formed. The first trailing bit 30 is formed in the embodiment shown only from a trailing chisel tip 32. This has a base support 33. The base support is cylindrical. It is made of a hard material, in this case made of hard metal. A superhard material 34, in the present case in the form of a polycrystalline diamond, is connected to the base support 33. The superhard material 34 forms the base support 33 facing away from a trailing cutting edge 35. He is cone-shaped and adapted to the base support 33 adapted to the outer cylindrical contour. As a result, the base support 33 is completely covered by the superhard material 34 at the end. Opposite the trailing edge 35 of the base support 33 is inserted into the Lötausnehmung 45.2 of the first trailing approach 45 and soldered to it.

FIG. 3 shows, in a side view, the tool combination 50 shown in FIG. 2, mounted on the base part 60. For this purpose, as already described for FIG. 2, the bit holder 40 is inserted with its plug projection 44 into a socket of the base part 60 and fixed therein by means of a clamping screw , The base part 60 is connected along its underside 61 with the not shown in Figure 3 Fräswalzenrohr the milling drum 15 shown in Figure 1, in particular welded.

Starting from the rotation axis 15.1 of the milling drum 15 shown in FIG. 1, a larger radius 70 and a smaller radius 71 are represented by corresponding arrows. The larger radius 70 indicates a larger cutting circle 70.1 and the smaller radius 71 has a smaller cutting circle 71 .1. The leading edge 23 of the leading bit 20 is disposed on the larger radius 70. The trailing cutting edge 35 of the first trailing bit 30 lies on the smaller radius 71. Upon rotation of the milling drum 15 along the marked by the arrow working movement 76 is thus without advancing the tillage machine 10, the leading edge 23 of the leading bit 20 along the larger cutting circle 70.1 and the trailing edge 35 of the first trailing bit 30 along the smaller cutting circle 71 .1 emotional.

Starting from the axis of rotation 15.1 of the milling drum 15, two radial lines 72 are each guided by the leading cutting edge 23 of the leading chisel 20 and the trailing cutting edge 35 of the first trailing chisel 30. There they intersect a leading center line 73.1 of the leading bit 20 and a trailing center line 73.2 of the first trailing bit 30. The leading center line 73.1 is aligned along the axis of symmetry of the leading bit 20 in the direction of its longitudinal extent. Correspondingly, the trailing center line 73.2 extends along the axis of symmetry of the first trailing bit 30. The leading center line 73.1 indicates the orientation of the leading bit 20, while the trailing center line 73.2 marks the orientation of the first trailing bit 30. The leading chisel 20 and the first trailing chisel 30 are each aligned in a marked by a double arrow angle of attack 74 relative to the associated radial line 72. In this case, the setting angle 74 of the first trailing bit 30 is selected to be smaller than the setting angle 74 of the leading bit 20.

FIG. 4 shows a side view of a tool combination 50 with a bit holder 40, a leading bit 20 and a second trailing bit 31. The construction of the leading bit 20 and its attachment to the bit holder 40 correspond to the structure described above or the attachment described above, so that reference is made to this description is taken. The leading approach 41, the base 43 and the plug-in projection 44 correspond to the description of Figures 2, 3 and 6.

The second trailing bit 31 has a base 36 which is integrally connected to a shaft 37 shown in FIG. Starting from the cylinder-shaped shaft 37, the base 36 tapers to the diameter of the base support 33 of the trailing chisel tip 32. The base 36 is formed from a hard material, in this case made of hard metal. The base support 33 of the trailing chisel tip 32 is placed on the base 36 and connected thereto, in particular soldered. Opposite the base 36 covers a super hard material 34, in the present case in the form of a polycrystalline diamond, the base support 33 from. The superhard material 34 is firmly connected to the base support 33. Facing away from the base support 33, the superhard material 34 forms the trailing edge 35 of the second trailing bit 31. As shown in Figure 6, the shaft 37 of the second trailing bit 31 is held in a trailing bit receptacle 46.2. The trailing bit receptacle 46.2 is designed as a bore in a second trailing projection 46 of the bit holder 40. In this case, the trailing bit receptacle 46.2 is formed starting from a second front side 46.1 of the second trailing shoulder 46 in this. The shaft 37 of the second trailing bit 31 is fixed both circumferentially and axially in the trailing bit receptacle 46.2. The non-positive connection between the shaft 37 and the trailing chisel holder 46.2 takes place here by means of cold stretching or shrinking. For this purpose, the shaft 37 is manufactured with an interference fit with respect to the trailing bit receptacle 46.2. For joining the shaft 37 is cooled so far that it can be inserted into the trailing bit holder 46.2. In the subsequent warming up of the shaft 37, this expands due to the thermal expansion, so that a frictional connection between the shaft 37 and the trailing bit holder 46.2 is formed. In addition to the non-positive connection of the shaft 37 with the trailing bit holder 46.2 by cold stretching or shrinking, other non-positive, positive or material connections are conceivable. These can be, for example be designed as a screw, as a solder joint, as a welded joint or as an adhesive bond. Preferably, the shaft 37 is formed of a hard material, in particular of hard metal.

The second trailing shoulder 46 is, based on the working movement 76 of the material combination 50, disposed behind the leading lug 41. Thus, the second trailing chisel 31, based on the working movement 76, positioned behind the leading chisel 20. When the tool combination 50 is mounted, the leading edge 23 on the larger radius 70 and the trailing edge 35 of the second trailing bit 31 on the smaller radius 71 are arranged, as shown in FIG. 3 for a tool combination 50 with a first trailing bit 30. The second trailing bit 31 is also aligned at a smaller angle of incidence 74 (see FIG. 3) with respect to an associated radial line 72 than the leading bit 20.

FIG. 5 shows the tool combination 50 shown in FIG. 4 in a plan view. Identical components are the same as previously introduced.

A center plane 75 of the tool combination 50 is marked by a dashed line. The center plane 75 refers to the insertion lug 44, the base 43 and the leading lug 41 of the chisel holder 40 and the leading chisel 20. It therefore runs centrally through the leading chisel tip 22. The second trailing chisel 31 is laterally offset to the center plane 75th arranged. Thereby, the tool combination 50 with the two chisels 20, 30, 31 in the direction of the longitudinal extent of the milling drum 15 obliquely inclined to this be attached, the second trailing bit 31 follows upon rotation of the milling drum 15 of the path of the leading bit 20. As a result of the oblique arrangement, the leading chisel 20, which is mounted so as to be rotatable about its center longitudinal axis, obliquely penetrates into the soil material to be ablated. This causes the leading bit 20 to rotate about its central longitudinal axis and thereby become evenly worn along its circumference. FIG. 6 shows the tool combination 50 shown in FIGS. 4 and 5 in a lateral sectional representation. As described above, the leading bit 20 is rotatable on its bit shaft 24 by means of the clamping sleeve 25, but axially blocked, held in the leading bit receptacle 42 of the bit holder 40. The second trailing bit 31 is set with its shaft 37 both circumferentially and axially blocked in the trailing bit receptacle 46.2 of the second trailing approach.

In the case of the tool combinations 50 shown in FIGS. 2 to 6, the leading chisel 20 and the respective trailing chisel 30, 31 are arranged relative to one another such that in the case of a tool combination 50 mounted on a milling drum 15, the trailing chisel 30, 31 is moved along the same milling line As the leading chisel 20. The respective trailing chisel 30, 31 is thus arranged with respect to the working movement 76 of the tool combination 50 behind the leading chisel 20. As a result, the trailing chisel 30, 31 is arranged protected by the leading chisel 20.

The leading chisel 20 is dimensioned larger than the trailing chisel 30, 31 transversely to the working movement 76, so that it projects beyond it on both sides. As a result, the soil material removed by the leading chisel 20 is guided past the trailing chisel 30, 31 as far as possible. Also, the leading chisel 20 and / or the wear shield 26 and / or the leading lug 41 covers the joining region between the trailing chisel 30, 31 and the trailing lug 45, 46 of the chisel holder 40 along the working movement 76. The joining region between the trailing chisel 30, 31 and the trailing shoulder 45, 46 of the chisel holder 40 is thus protected from high abrasive wear. As a result, it can be reliably avoided that the trailing shoulder 45, 46 washes out and the joining surface between the trailing bit 30, 31 and the trailing shoulder 45, 46 is thereby exposed. This avoids that the trailing chisel 30, 31 is lost due to the wear of the chisel holder 40. The trailing chisel tip 32 of the trailing chisel 30, 31 is at least partially formed of a superhard material. Thus, the trailing chisel tip 32 is formed harder compared to the leading chisel tip 22 of the leading chisel 20, which is preferably made of a hard metal. The trailing chisel tip 32 and thus the trailing chisel 30, 31 are thus much more resistant to abrasive wear formed as the leading chisel tip 22 and thus the leading chisel 20. Combined with the previously described, protected arrangement of the trailing chisel 30, 31 has this one significantly longer life than the leading chisel 20 on. The service life of the trailing bit 30, 31 is with appropriate design and arrangement of the trailing bit 30, 31 in the order of the life of the bit holder 40. Thus, the trailing bit 30, 31 are not interchangeable connected to the bit holder 40, in particular not destructive interchangeable be connected to the bit holder 40. By contrast, the leading chisel 20 exposed to strong mechanical wear is fastened to the chisel holder 40 in an easily replaceable manner. When worn leading chisel 20 this can thus be easily replaced. Since the trailing chisel 30, 31 no longer needs to be replaced due to its long service life, maintenance with corresponding downtime of the tillage machine 10 are only provided for the replacement of the leading chisel 20. As a result, the operating costs of the tillage machine 10 can be kept low.

The superhard material is in the present case designed as a polycrystalline diamond. It may be formed according to the present invention as a diamond material, as a diamond-reinforced material, as a silicon carbide material, as a cubic boron nitride or as compounds of at least two of the aforementioned materials. All of these materials or combinations of materials have a greater hardness than the hard metal from which the leading bit is made, and thus greater resistance to wear. In addition to the polycrystalline diamond may also be a diamond diamond, a monocrystalline diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, one or more sequential diamond layers, thermally stable diamond or silicon bonded diamond.

During a milling process, the tool combination 50 is moved due to the rotation of the milling drum 15 and the feed of the tillage machine 10 by the soil material to be removed. The trailing cutting edge 35 of the trailing bit 30, 31 is, based on the axis of rotation 15.1 of the milling drum 15, arranged on a smaller radius 71 or a same radius as the leading edge 23 of the leading bit 20. Thereby, and by the reduced geometry of the trailing bit 30, 31 opposite the leading bit 20, the leading bit 20 cuts a larger volume than the trailing bit 30, 31. According to the invention, the trailing chisel 30, 31 is designed and arranged to rework the milling of the leading chisel 20. In this case, in particular of the leading chisel 20 a coarser milling and of the trailing chisel 30, 31 performed a finer milling. Correspondingly, the trailing cutting edge 32 of the trailing bit 30, 31 is arranged spatially with respect to the leading edge 23 of the leading bit 20, that at predetermined operating parameters of the tillage machine 10, each of the bits 20, 30, 31 has a suitable depth of penetration into the soil material for its task ,

To carry out a fine milling, for example, a penetration depth of less than 15 mm is suitable for the trailing chisel 30, 31. Typical operating parameters of the tillage machine 10 for such a milling process are a rotational speed of the milling drum 15 of 130 revolutions / min, a feed rate of the tillage machine 10 of 20 m / min and a cutting depth of 100 mm. The larger cutting circle 70.1 of the leading edge 23 is for example approximately 980 mm. From the cutting depth of 100 mm and the larger cutting circle 70.1 results in a milling angle of 37.25 °, within which the chisel 20, 30, 31 in operated with feed tillage machine 10 in the soil material intervene. From the engagement of the tool combination in the ground to its exit from the ground, the soil tillage machine 10 moves forward about 15 mm. In order to obtain the desired fine finish with the trailing bit 30, 31, as is suitable for carrying out a fine milling, the smaller radius 71, on which the trailing cutting edge 35 of the trailing bit 30, 31 is arranged, must therefore be in the range of a maximum of less than 3 mm be chosen as the larger radius 70 on which the leading edge 23 of the leading bit 20 is arranged. By suitable arrangement of the trailing edge 35 of the trailing bit 30, 31, based on the leading edge 23 of the leading bit 20, thus the penetration depth of the trailing bit in the soil material for predetermined operating parameters of the soil cultivation machine 10 can be determined and specified. This makes it possible for the leading chisel 20, for example, to perform a rough milling task, for example roughing, while the trailing chisel 30, 31 is designed for a fine milling, for example, finishing. The trailing chisel 30, 31 thus works on the milling of the leading chisel 20 after. He determines the resulting milling image. Due to the very low wear of the trailing bit 30, 31 this milling remains at least largely the same even after a long period of use of the tool combination 50 and high wear of the leading bit 20. If the leading chisel 20 wears out a bit, then the trailing chisel 30 additionally takes over part of the working function of the leading chisel 20 while maintaining a high surface quality milling pattern.

It is also conceivable to design the system such that, under the assumed machine parameters, the trailing chisel 30 has a cutting depth of 0 at the beginning of the working operation. Only when the leading chisel 20 begins to wear, the trailing chisel 30 comes into action and performs a material removal. He then works, as described above, the milling of the leading bit 20 after. This results in a perfect milling pattern again. The leading chisel 20 is held about its central longitudinal axis rotatably in the leading chisel receptacle 42 of the chisel holder 40. Upon engagement of the leading bit 20 in the removed soil material this is rotated about its central longitudinal axis. As a result, the leading chisel 20 is circumferentially worn evenly, which significantly extends its life. The trailing chisel 30, 31, however, is not rotatably connected to the bit holder 40. Due to the very high hardness of the trailing chisel tip 32, only an insignificant wear of the trailing chisel 30, 31 occurs, so that no rotatable mounting of the trailing chisel 30, 31 is required. The rigid connection of the trailing bit 30, 31 with the bit holder 40 vibrations in the trailing bit tip 32 can be avoided. Such vibrations can lead to breakage of the superhard material 34.

Claims

claims

1 . Tool combination (50) comprising a bit holder (40) attachable to a milling drum (15) of a soil tillage implement (10), and at least one leading and one trailing bit (20, 30, 31) held on the bit holder (40) wherein the trailing bit (30, 31) is located behind the leading bit (20) relative to a working movement (76) of the tool combination (50) when inserted into the soil tillage implement (10) and wherein each bit (20, 30 , 31) has a chisel tip (22, 32) with a cutting edge (23, 35),

characterized,

that the trailing chisel tip (32) of the trailing chisel (30, 31) at least partially has a greater hardness than the leading chisel tip (22) of the leading chisel (20).

2. tool combination (50) according to claim 1,

characterized,

the trailing chisel tip (32) is formed, at least in some areas, from a superhard material, in particular a diamond material, a diamond-reinforced material, a silicon carbide material, cubic boron nitride or compounds of at least two of the abovementioned materials.

3. tool combination (50) according to claim 2,

characterized,

the diamond material is at least partially formed as monocrystalline diamond or as polycrystalline diamond or as chemically deposited diamond or as physically deposited diamond or as natural diamond or as infiltrated diamond or as diamond layer or as successive diamond layers or as thermally stable diamond or as silicon-bonded diamond.

4. tool combination (50) according to claim 2 or 3,

characterized,

in that the trailing chisel tip (32) is formed from a base support (33) made of a hard material, preferably of hard metal, which is covered by the superhard material towards the trailing cutting edge (35).

5. tool combination (50) according to one of claims 2 to 4,

characterized,

that the superhard material is formed as a layer.

6. tool combination (50) according to one of claims 1 to 5,

characterized,

that the trailing bit (30, 31) is axially and circumferentially fixedly connected to the bit holder (40) and / or that the leading bit (20) is held axially and rotatably connected in its circumferential direction to the bit holder (40).

7. tool combination (50) according to any one of claims 1 to 6,

characterized,

in that the trailing chisel (30, 31) is not exchangeably connected to the bit holder (40) and / or that the leading chisel (20) is exchangeably connected to the chisel holder (40).

8. tool combination (50) according to one of claims 1 to 7,

characterized,

in that the trailing chisel (30, 31) is formed from the trailing chisel tip (32) which is not detachably connected, in particular soldered, directly to the chisel holder (40) and / or that the trailing chisel (30, 31) is at least of the trailing chisel tip (32) and a thus directly or indirectly connected shaft (37) is formed and that the shaft (37) in a trailing chisel receptacle (46.2) of the chisel holder (40) is held, preferably by means of a cohesive, a non-positive or a positive connection.

9. tool combination (50) according to one of claims 1 to 8,

characterized,

in that the trailing chisel (30, 31) is designed and arranged to rework a milling performed by the leading chisel (20).

10. tool combination (50) according to any one of claims 1 to 9,

characterized,

in that the trailing chisel (30, 31) is designed and arranged to cut a smaller chip volume from the material to be abraded than the leading chisel (20).

1 1. Tool combination (50) according to one of claims 1 to 10,

characterized,

in that the leading chisel (20) and the trailing chisel (30, 31) are designed and arranged on the chisel holder (40) such that, in the case of a tool combination (50) mounted on a milling drum (15), the leading edge (23) of the leading chisel Chisel tip (22) of the leading chisel (20) on a larger radius (70) to a rotation axis (15.1) of the milling drum (15) is arranged as the trailing edge (35) of the trailing chisel tip (32) of the trailing chisel (30, 31 ) or that the two cutting edges are arranged on substantially the same radii.

12. tool combination (50) according to any one of claims 1 to 1 1,

characterized,

in that the spacing of the cutting edges (23, 35) of the chisel tips (22, 32) from one another and the radii (70, 71) on which the cutting edges (23, 35) of the tool combination (50) mounted on a milling drum (15) are Chisel tips (22, 32) are arranged, are selected such that in a predetermined feed speed of the soil tillage machine (10) and a predetermined speed of the milling drum (15) of the trailing chisel (30, 31) has a predetermined penetration depth in the material to be milled.

13. tool combination (50) according to any one of claims 1 to 12,

characterized,

the distance between the cutting edges (23, 35) of the leading chisel tip (20) and the trailing chisel tip (32) is between 45 mm and 75 mm, preferably between 50 mm and 60 mm, particularly preferably 54 mm, and / or that the radius (70, 71 ), on which the trailing cutting edge (35) of the trailing chisel tip (32) is arranged at a tool combination (50) mounted on a milling drum (15) is between 1 mm and 7 mm, preferably between 2 mm and 5 mm, particularly preferably 3 mm, smaller is as the radius (70, 71) on which the leading edge (23) of the leading chisel tip (22) is arranged.

14. Tool combination (50) according to one of claims 1 to 13,

characterized,

in that the trailing bit (30, 31) is aligned at a smaller angle of incidence (74) relative to a radial line (72) passing through the trailing edge (35) than the leading bit (20) relative to a radial line passing through the leading edge (23) (72), preferably that the trailing chisel (30, 31) at an angle between 25 ° and 35 ° and the leading chisel (20) are aligned at an angle between 35 ° and 45 ° relative to the respective associated radial line (72).

15. Tool combination (50) according to one of claims 1 to 14,

characterized,

a joining zone formed between the trailing chisel (30, 31) and the chisel holder (40) is at least partially covered by the leading chisel (20) along the working movement (76) of the tool combination (50).

16. tool combination (50) according to any one of claims 1 to 15,

characterized,

in that the leading chisel (20) projects transversely to the working movement (76) of the tool combination (50) beyond the trailing chisel (30, 31).