EP3563000B1 - Tool combination having a chisel holder and two chisels - Google Patents

Description

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

Such a tool combination is from the U.S. 4,342,486 known. The document shows a milling drum with a chisel holder designed to hold two milling chisels. The chisels are arranged one after the other in the direction of rotation of the milling drum. A first chisel, which is front in the direction of rotation, is arranged in such a way that its chisel tip is moved over a larger radius around the axis of rotation of the milling drum than the chisel tip of the trailing second chisel. The soil material is first removed by the engagement of the first chisel. If the first chisel breaks, the second chisel takes over the machining function. The second chisel thus takes on a safety function which enables further milling even if the first chisel is damaged or lost and at the same time protects the chisel holder and the milling drum. The chisels are aligned parallel to each other. They are interchangeably connected to the chisel holder so that they can be exchanged when they wear out. The same chisels or chisels in different lengths, but with the same holding mechanism for fastening to the chisel holder and the same structure of the chisel tips, can be provided.

The font U.S. 5,582,468 describes a chisel holder for a soil cultivating machine that can be attached to a milling drum. The chisel holder has two bores for receiving two chisels. The chisels are arranged one behind the other in the direction of rotation of the milling drum. The holes are aligned obliquely to a radial line of the milling drum and pointing in the direction of rotation, so that the chisels hit the substrate to be processed at a desired angle. The bores are furthermore arranged on different radii, the bore arranged further forward in the direction of rotation being on a smaller radius than the rear bore. As a result, a tip of a chisel received in the rear bore is moved over a larger radius around the axis of rotation of the milling drum than a tip of an identical front chisel. The rear chisel takes over the major part of the material removal. If the rear chisel breaks, the material removal is shifted towards the front chisel. The front bit is arranged to shield the bore and the outer edge of the rear bore in the direction of movement of the bit. This protects the rear chisel holder from excessive abrasive wear even if the rear chisel is defective or lost. The chisels are interchangeably connected to the chisel holder so that they can be exchanged in the event of advanced wear or damage.

In the WO 2013/064433 describes a chisel point for a chisel, as it can be used for a soil tillage machine. The tip has a 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 shows very little wear. As has been shown in the application, with 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 can be lost. Furthermore, it can happen that a used chisel can no longer be installed in a new chisel holder due to its, albeit slight, wear in the connection area. Because of the diamond tipping, the chisels are very expensive to produce. Lost chisels or chisels that are no longer usable increase the operating costs of the tillage machine significantly.

The document US 2001/004946 A1 shows polycrystalline diamond compacts which are used as the cutting element of a drill bit for drilling through rock. The roller cone bit of the cutting tool has three rotating cones with several cutting teeth, the diamond surface being exposed outside the cutting tool. The diamond surface of the incisors is generally cylindrical in shape with a hemispherical diamond surface, the tip of which is formed on the central axis. It can also be provided to offset the tip from the central axis or to coat the diamond layer with a substrate. The polycrystalline diamond area can also be conical in shape.

It is the object of the invention to create a tool for a soil cultivating machine which enables cost-effective operation of the soil cultivating machine with long maintenance intervals.

The object of the invention is achieved in that 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. The trailing chisel tip follows the track of the leading chisel tip during a milling process. As a result, the trailing chisel point is less stressed and is therefore exposed to less wear than the leading chisel point. 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 to such an extent that it no longer needs to be replaced, or only very rarely. The maintenance intervals are therefore based solely on the wear and tear of the leading chisel. Furthermore, the leading chisel protects the area in which the trailing chisel is held on the chisel holder. This significantly reduces the wear of the bit holder in the joint area between the trailing bit and the bit holder. A loss of the trailing chisel can thus be avoided. The less frequently required maintenance and the avoidance of losing the trailing chisels can significantly reduce the operating costs of the tillage machine.

According to a particularly preferred embodiment of the invention, it can be provided that the trailing chisel tip is formed at least in some areas from a super-hard material, in particular from a diamond material, a diamond-reinforced material, a silicon carbide material, from cubic boron nitride or from compounds of at least two of the aforementioned materials . By using such a super-hard material for at least partially forming the trailing chisel tip, the service life of the trailing chisel can be extended to the service life of the chisel holder. It is therefore no longer necessary to replace the trailing chisel and the maintenance intervals for the chisels are based solely on the wear and tear of the leading chisel. With the use of diamond materials or diamond-reinforced materials, extremely resistant chisels can be provided which, even with a comparatively high mechanical load on the trailing chisel, have a service life in the range of the service life of the bit holder. Chisel tips that are formed at least in some areas from a silicon carbide material or from cubic boron nitride, on the other hand, are more cost-effective to produce. For example, for arrangements and applications in which the trailing chisel tip is exposed to less mechanical stress, they have a life expectancy that is adapted to the service life of the chisel holder. The resistance of the trailing chisel can be adapted to the expected load by appropriate connections of the materials mentioned.

A very high mechanical load capacity of the trailing chisel can be obtained if the diamond material is at least partially 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 is designed as a thermally stable diamond or as a silicon-bonded diamond. By using monocrystalline diamonds, chisel tips with the highest wear resistance can be obtained.

When using polycrystalline diamonds or chemically or physically deposited diamonds, degrees of hardness of the chisel tips can be achieved which at least approximately correspond to the hardness of monocrystalline diamonds. Polycrystalline diamonds or chemically or physically deposited diamonds are more cost-effective to provide than monocrystalline diamonds. Infiltrated diamonds allow the properties of the chisel tip to be adapted to the expected requirements and loads within a given framework. 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 manufacturing costs can be reduced. The properties of the diamond layers can be adapted to the respective requirements by means of successive diamond layers. For example, an outer diamond layer can be made very hard and therefore mechanically resilient, while an inner diamond layer is adapted for a firm and permanent connection to a substrate as part of the chisel tip on which the diamond layers are deposited. Thermally stable diamonds enable manufacturing processes for the chisel or the chisel tip that require high temperatures, for example soldering processes. With silicon-bonded diamond, small diamond segments are connected by means of silicon. The small diamond segments can be produced comparatively inexpensively and can be present as monocrystals, for example. Silicon-bonded diamond can easily be adapted to the desired contour of the trailing chisel tip and its cutting edge.

A highly resilient and at the same time easily and mechanically fixedly connectable to another workpiece can be obtained in that the trailing chisel point is formed from a base carrier made of a hard material, preferably hard metal, which is covered by the super-hard material facing the trailing cutting edge . The trailing edge is thus formed from the super-hard material. The base carrier consisting of the hard material can be soldered to a further section of the trailing chisel, for example a chisel head.

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

According to a preferred embodiment of the invention, it can be provided that the trailing chisel is axially and fixedly connected to the chisel holder in its circumferential direction and / or that the leading chisel is axially held and rotatably connected to the chisel holder in its circumferential direction. The non-rotatable attachment of the trailing chisel reduces vibrations during tool engagement. Such vibrations can lead to breakage of the super-hard and thus brittle material. Due to the rotatable mounting of the leading chisel, it is rotated about its longitudinal axis when it engages the soil material to be removed. This results in uniform, circumferential wear on the chisel tip and / or the chisel head. The service life of the leading chisel can thus be increased. Furthermore, due to the uniform circumferential wear, a self-sharpening of the leading chisel occurs. As a result, the leading chisel can penetrate the material to be removed comparatively easily, which reduces the energy costs for operating the soil cultivating machine.

Due to the at least regionally greater hardness of the trailing chisel tip, in particular in the case of a trailing chisel tip that is at least partially made of a super-hard material, as well as the lower mechanical load on the trailing chisel tip compared to the leading chisel tip, an almost unchanged cutting engagement of the trailing chisel tip can be achieved. The life expectancy of the trailing chisel is thus in the range of the life expectancy of the chisel holder. The life expectancy of the leading chisel is due to it lower hardness and its higher mechanical load during use less than that of the trailing chisel and the chisel holder. It can therefore be provided that the trailing chisel is not interchangeably connected to the chisel holder in a non-destructive manner and / or that the leading chisel is interchangeably connected to the chisel holder. The trailing chisel thus remains connected to the chisel holder over the entire service life of the chisel holder. The leading chisel, which is significantly more cost-effective to produce than the trailing chisel, can be replaced when its wear limit is reached.

According to the invention, it can be provided that the trailing chisel is formed from the trailing chisel tip, which is not detachably connected, in particular soldered, directly to the chisel holder, and / or that the trailing chisel is at least made up of the trailing chisel tip and a direct or indirect one connected shank is formed and that the shank is held in a trailing chisel receptacle of the chisel holder, preferably by means of an integral, non-positive or 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 carrier can be formed from a hard material, preferably from hard metal, which is covered by the super-hard material facing the trailing cutting edge. The base carrier can be connected directly to the chisel carrier. A resilient and inexpensive connection can be made, for example by soldering. The base support is dimensioned in such a way that it can be introduced into a production unit for connection to a super-hard material. The chisel tip produced in this way can be connected directly to the chisel carrier. It is also possible to connect the chisel tip directly or indirectly, for example via a chisel head arranged between the chisel tip and the shank, to a shank. The shank can then be connected to the bit carrier in the trailing bit holder. The connection between the shank and the chisel holder can be firmly bonded, for example by soldering or gluing, respectively. Non-positive connections are also possible. Such a non-positive connection can be produced, for example, by cold stretching or shrinking the shank into the trailing chisel receptacle. The shaft is made with an oversize, cooled and inserted into the following chisel holder. When it warms up, it expands and forms a firm connection to the chisel holder that follows. Correspondingly, the connection can be made by shrinking on, the chisel holder being warmed up and the oversized shank of the trailing chisel being inserted into the trailing chisel receptacle which is enlarged by the increased temperature. It is also conceivable to provide a screw connection between the shank and the chisel holder.

A uniform milling pattern can be obtained in that the trailing chisel is designed and arranged to rework a milling made by the leading chisel. By reworking the milling with the following chisel, the milling pattern is retained, regardless of the state of wear of the leading chisel. This applies in particular to trailing chisels, each with a trailing chisel tip equipped with a super hard material, which guarantees an almost unchanged cutting action over a long period of time.

A uniform milling pattern on the one hand and a comparatively low mechanical load and thus a low level of wear on the trailing chisel on the other hand can be achieved in that the trailing chisel is designed and arranged to remove a smaller chip volume than the leading chisel Cut material.

In order to rework the milling of the leading chisel by the trailing chisel, the invention provides that the leading chisel and the trailing chisel are designed and arranged on the chisel holder in such a way that, when a tool combination is mounted on a milling drum, the leading edge of the leading chisel tip of the leading chisel on one larger radius is arranged to an axis of rotation of the milling drum than the trailing edge of the trailing chisel tip of the trailing chisel or that the two cutting edges are arranged on substantially the same radii. Essentially equal here means, in particular, radii that are equal to ± 3 mm. With this arrangement of the chisel tips, the trailing chisel removes a significantly smaller chip volume than the leading chisel. In this way, a uniform removal of the substrate to be processed can be achieved, which leads to 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 first penetrates the substrate to be worked, followed by the trailing chisel. The paths on which the leading edge and the trailing edge are guided through the material to be processed are dependent on at least the milling depth, the speed of the milling drum and the feed speed of the soil cultivating machine. The volume of material removed by each chisel thus depends at least on these machine parameters and on the relative arrangement of the trailing edge of the trailing chisel to the leading edge of the leading chisel.

By means of machine parameters that are coordinated with one another and the arrangement of the cutting edges, it can be achieved that the leading chisel cuts a larger volume than the trailing chisel. Thus, for example, the leading chisel can be provided for roughing and the trailing chisel for finishing. Due to the advancing chisel, the largest part of the to The surface to be processed is removed while the desired milling pattern is produced by the trailing chisel.

An adaptation to common machine parameters of the soil tillage machine can be achieved in that the distance between the cutting edges of the leading chisel tip and the trailing chisel tip is between 45mm and 75mm, preferably between 50mm and 60mm, particularly preferably 54mm, and / or that the radius on which In the case of a tool combination mounted on a milling drum, the trailing edge of the trailing chisel tip is arranged to be between 1 mm and 7 mm, preferably between 2 mm and 5 mm, particularly preferably 3 mm, 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 chisel is oriented at a smaller angle of attack with respect to a radial line running through the trailing edge than the leading chisel is aligned with a radial line running through the leading edge, preferably that the trailing chisel is oriented at an angle of between 25 ° and 35 ° ° and the leading chisel are aligned at an angle of incidence between 35 ° and 45 ° with respect to the respective assigned radial line. Due to the larger setting angle of the leading chisel, in particular between 35 ° and 45 °, a self-sharpening of the leading chisel is achieved for all common milling tasks. Due to the smaller setting angle of the trailing chisel, in particular in a range between 25 ° and 35 °, it is aligned in the direction of the resulting force, in particular during fine milling.

According to a particularly preferred embodiment of the invention, it can be provided that a joining zone formed between the trailing chisel and the chisel holder is at least partially covered by the leading chisel along the working movement of the tool combination. The ground material removed by the leading chisel is thus formed between the trailing chisel and the chisel holder Joining zone slides past. This avoids excessive wear of the bit holder in the area of the joining zone. A loss of the trailing chisel can thus be prevented.

The mechanical load on the trailing chisel, which may not be non-destructively replaceable, can be kept low in that the leading chisel protrudes beyond the trailing chisel transversely to the working movement of the tool combination. The soil material removed by the leading chisel is thus slid laterally past the trailing chisel. This can significantly increase the service life of the trailing chisel. The leading chisel preferably projects over the trailing chisel on both sides.

Fig. 1

in schematischer Darstellung und Seitenansicht eine Bodenbearbeitungsmaschine in Form einer Straßenfräsmaschine,

Fig. 2

in einer Seitenansicht eine Werkzeugkombination mit einem Meißelhalter, einem vorlaufenden Meißel und einem ersten nachlaufenden Meißel,

Fig. 3

in einer Seitenansicht die in Fig. 2 gezeigte Werkzeugkombination, montiert auf einem Basisteil,

Fig. 4

in einer Seitenansicht eine Werkzeugkombination mit einem Meißelhalter, einem vorlaufenden Meißel und einem zweiten nachlaufenden Meißel,

Fig. 5

die in Fig. 4 gezeigte Werkzeugkombination in einer Draufsicht und

Fig. 6

die in den Figuren 4 und 5 gezeigte Werkzeugkombination in einer seitlichen Schnittdarstellung.

The invention is explained in more detail below using an exemplary embodiment shown in the drawings. Show it:

Fig. 1

a schematic representation and side view of a soil cultivation machine in the form of a road milling machine,

Fig. 2

a side view of a tool combination with a chisel holder, a leading chisel and a first trailing chisel,

Fig. 3

in a side view the in Fig. 2 Tool combination shown, mounted on a base part,

Fig. 4

a side view of a tool combination with a chisel holder, a leading chisel and a second trailing chisel,

Fig. 5

in the Fig. 4 Tool combination shown in a plan view and

Fig. 6

those in the Figures 4 and 5 Tool combination shown in a lateral sectional view.

Figure 1 shows a schematic representation and side view of a soil cultivating machine 10 in the form of a road milling machine. A machine frame 12 is supported in a height-adjustable manner by trolleys 11.1, 11.2, for example crawler tracks, via four lifting columns 16.1, 16.2. Starting from a control station 13, the soil cultivating machine 10 can be operated via a control 17 arranged in the control station 13. In a concealed milling drum box, a milling drum 15, which is likewise arranged in a concealed manner and shown in dashed lines in the illustration, is rotatably mounted about an axis of rotation 15.1. A conveyor 14 is used to transport away the milled material.

In use, the machine frame 12 is moved over the substrate to be processed at a feed rate entered via the control 17. Here wear on the rotating milling drum 15 arranged and in the Figures 2 to 6 shown chisels 20, 30, 31 from the ground. The height position and the speed of the milling drum 15 can be set by the controller 17. The milling depth is set via the height position of the milling drum 15. The height position of the milling drum can take place via the height-adjustable lifting columns 16.1, 16.2, depending on the machine type. Alternatively, the milling drum 15 can be adjustable in height relative to the machine frame 12.

Figure 2 shows a side view of a tool combination 50 with a chisel holder 40, a leading chisel 20 and a first trailing chisel 30. The leading chisel 20 has a chisel head 21 and a one-piece, in Figure 6 chisel shank 24 shown. The chisel head 21 carries a leading chisel tip 22, consisting of a hard material, for example hard metal. At the end, the leading chisel tip 22 forms a leading cutting edge 23.

The leading chisel tip 22 is usually soldered to the chisel head 21 along a contact surface. For this purpose, a receptacle 21.2 is incorporated into the chisel head 21, into which the chisel tip 22 is inserted and soldered.

As in Figure 6 As shown, the chisel shank 24 carries a longitudinally slotted, cylindrical clamping sleeve 25. This is held on the chisel shank 24 so that it cannot be lost in the direction of the longitudinal extension of the leading chisel 22, but is freely rotatable in the circumferential direction. A wear protection disk 26 is arranged in the area between the clamping sleeve 25 and the chisel head 21. In the assembled state, the wear protection disk 26 is supported on a mating surface of the chisel holder 40 and the chisel holder 40 facing away from the underside of the chisel head 21, which is enlarged in diameter in this area by a collar 21.1.

The chisel holder 40 is equipped with a leading extension 41 into which, as in FIG Figure 6 is shown, a leading chisel receptacle 42 is incorporated in the form of a cylindrical bore. In this leading chisel receptacle 42, the clamping sleeve 25 is held clamped with its outer circumference on the inner wall of the bore. The leading chisel receptacle 42 opens into an expulsion opening 47. An expulsion mandrel (not shown) can be inserted through this for the purpose of dismantling the advancing chisel 20. This acts on the end of the chisel shaft 24 in such a way that the leading chisel 20 is pushed out of the leading chisel receptacle 42 while the clamping force of the clamping sleeve 25 is overcome.

The leading extension 41 is molded onto a base 43 of the chisel holder 40. Laterally offset and opposite to the leading extension 41, a plug-in extension 44 is connected in one piece to the base 43. The plug attachment 44 can be inserted into a plug receptacle of an in Figure 3 The base part 60 shown is inserted and clamped there by means of a clamping screw, not shown. For this purpose, the plug-in extension 44 has an in Figure 2 shown clamping surface 44.1 on which the clamping screw engages. To the side of the plug-in projection 44, the base part 43 has contact surfaces 43.1 with which it is mounted under the action of force of the clamping screw to the in Figure 3 shown base part 60 is pressed. The base part 60 itself is on its underside 61 on a milling drum tube of the in Figure 1 indicated milling drum 15 welded on. In the present exemplary embodiment, four contact surfaces 43.1 are provided on the base part 43. These are two rear contact surfaces 43.1, which are arranged at least in some areas behind the plug-in attachment 44. Furthermore, two front contact surfaces 43.1 are used, which are arranged at least in some areas in front of the plug-in attachment 44. The two rear contact surfaces 43.1 are at an angle to one another. The two front contact surfaces 43.1 are also at an angle to one another. The rear contact surfaces and the front contact 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 plug-in attachment side 44 in the direction of the machining side defined by the chisels 20, 30. In addition, the front contact surfaces 43.1 are at an angle to the rear contact surfaces 43.1

As an alternative to the four contact surfaces 43.1, which in particular can be inclined more pyramidal to one another, it is conceivable to use three contact surfaces 43.1 which are at an angle to one another and are also inclined in a pyramid-like manner to one another. It can be provided that a contact surface 43.1 is provided at least in some areas behind the plug-in attachment 44 in the direction of movement and two contact surfaces 43.1 are provided at least in some areas in front of the plug-in attachment 44 in the direction of movement. Conversely, it is also conceivable that in the area behind the plug-in attachment 44, two contact surfaces 43.1 at an angle to one another, and at least in some areas in front of the plug-in attachment 44, a contact surface 43.1 is provided in the direction of movement.

The contact surfaces 43.1 serve to support the chisel holder 50 on the base part 60. Accordingly, the base part 60 has corresponding support surfaces on which the contact surfaces 43.1 of the chisel holder 50 sit.

As a result of the rotation of the milling drum 15 and the advance of the soil cultivating machine 10, the tool combination 50 is moved in accordance with a working movement 76 indicated by an arrow. In relation to this working movement 76, behind the leading projection 41, a first trailing projection 45 is integrally formed on the base 43 of the chisel holder 40. The leading extension 41 and the first trailing extension 45 are connected to one another along their sides facing one another. At its end facing away from the base 43, the first trailing extension 45 forms a first front side 45.1. A soldering recess 45.2 is formed in this first front side 45.1. In the embodiment shown, the first trailing chisel 30 is formed 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 hard metal. A super-hard material 34, in the present case in the form of a polycrystalline diamond, is connected to the base carrier 33. The super-hard material 34 forms a trailing cutting edge 35 facing away from the base carrier 33. For this purpose, it is conical and, facing the base support 33, is adapted to its outer cylindrical contour. As a result, the base carrier 33 is completely covered at the end by the super-hard material 34. Opposite to the trailing cutting edge 35, the base support 33 is inserted into the soldering recess 45.2 of the first trailing attachment 45 and soldered to it.

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

Based on the in Figure 1 1 of the milling drum 15 shown axis of rotation, a larger radius 70 and a smaller radius 71 are represented by corresponding arrows. The larger radius 70 characterizes a larger cutting circle 70.1 and the smaller radius 71 has a smaller cutting circle 71.1. The leading cutting edge 23 of the leading chisel 20 is arranged on the larger radius 70. The trailing cutting edge 35 of the first trailing chisel 30 lies on the smaller radius 71. When the milling drum 15 is rotated along the working movement 76 indicated by the arrow, the leading cutting edge 23 of the leading chisel 20 along the larger cutting circle 70.1 and the trailing cutting edge 35 of the first trailing chisel 30 moves along the smaller cutting circle 71.1.

Starting from the axis of rotation 15.1 of the milling drum 15, two radial lines 72 are each guided through the leading edge 23 of the leading chisel 20 and the trailing edge 35 of the first trailing chisel 30. There they cross a leading center line 73.1 of the leading chisel 20 or a trailing center line 73.2 of the first trailing chisel 30. The leading center line 73.1 is aligned along the axis of symmetry of the leading chisel 20 in the direction of its longitudinal extent. Correspondingly, the trailing center line 73.2 runs along the axis of symmetry of the first trailing chisel 30. The leading center line 73.1 indicates the alignment of the leading chisel 20, while the trailing center line 73.2 characterizes the alignment of the first trailing chisel 30. The leading chisel 20 and the first trailing chisel 30 are each aligned at an angle of attack 74, indicated by a double arrow, with respect to the assigned radial line 72. The setting angle 74 of the first trailing chisel 30 is selected to be smaller than the setting angle 74 of the leading chisel 20.

In Fig. 4 a tool combination 50 with a chisel holder 40, a leading chisel 20 and a second trailing chisel 31 is shown in a side view. The structure of the leading chisel 20 and its attachment to the chisel 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 extension 41, the base 43 and the plug-in extension 44 also correspond to the description of FIGS Figures 2 , 3rd and 6th .

The second trailing chisel 31 has a base 36 which is integral with an in Figure 6 Shaft 37 shown is connected. Starting from the cylindrical shaft 37, the base 36 tapers down to the diameter of the base carrier 33 of the trailing chisel tip 32. The base 36 is formed from a hard material, in the present case from hard metal. The base support 33 of the trailing chisel tip 32 is placed on the base 36 and connected to it, in particular soldered. Opposite the base 36, a super-hard material 34, in the present case in the form of a polycrystalline diamond, covers the base support 33. The super-hard material 34 is firmly connected to the base carrier 33. Facing away from the base carrier 33, the super-hard material 34 forms the trailing cutting edge 35 of the second trailing chisel 31. As in Figure 6 shown, the shaft 37 of the second trailing chisel 31 is held in a trailing chisel receptacle 46.2. The trailing chisel receptacle 46.2 is designed as a bore in a second trailing shoulder 46 of the chisel holder 40. The trailing chisel receptacle 46.2 is formed in the latter, starting from a second front side 46.1 of the second trailing extension 46. The shank 37 of the second trailing chisel 31 is fixed both in the circumferential direction and axially in the trailing chisel receptacle 46.2. The non-positive connection between the shank 37 and the trailing chisel receptacle 46.2 takes place in the present case by means of cold stretching or shrinking. For this purpose, the shank 37 is manufactured with an interference fit with respect to the trailing chisel receptacle 46.2. For joining, the shank 37 is cooled to such an extent that it can be pushed into the trailing chisel receptacle 46.2. During the subsequent warming up of the shank 37, it expands due to the thermal expansion, so that a non-positive connection is formed between the shank 37 and the trailing chisel receptacle 46.2. In addition to the non-positive connection of the shank 37 to the trailing chisel receptacle 46.2 by means of cold expansion or shrinking, other non-positive, positive or material-locking connections are also conceivable. These can for example be designed as a screw connection, a soldered connection, a welded connection or an adhesive connection. The shaft 37 is also preferably formed from a hard material, in particular from hard metal.

The second trailing attachment 46 is arranged behind the leading attachment 41 in relation to the working movement 76 of the material combination 50. The second trailing chisel 31 is thus also positioned behind the leading chisel 20 in relation to the working movement 76. When the tool combination 50 is mounted, the leading edge 23 is arranged on the larger radius 70 and the trailing edge 35 of the second trailing chisel 31 is arranged on the smaller radius 71, as shown in FIG Figure 3 for a tool combination 50 with a first trailing chisel 30 is shown. The second trailing chisel 31 is also at a smaller angle of attack 74 (see Figure 3 ) aligned with respect to an assigned radial line 72 as the leading chisel 20.

Figure 5 shows the in Figure 4 Tool combination 50 shown in a plan view. The same components are identified in the same way as previously introduced.

A central plane 75 of the tool combination 50 is marked by a dashed line. The center plane 75 relates to the plug-in attachment 44, the base 43 and the leading attachment 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 from the center plane 75 arranged. As a result, the tool combination 50 with the two chisels 20, 30, 31 can be attached to the milling drum 15 at an incline in the direction of its longitudinal extension, the second trailing chisel 31 following the path of the leading chisel 20 when the milling drum 15 rotates. The oblique arrangement ensures that the leading chisel 20, which is rotatably mounted about its central longitudinal axis, penetrates obliquely into the soil material to be removed. This has the effect that the leading chisel 20 rotates about its central longitudinal axis and is thereby worn evenly along its circumference.

Figure 6 shows the in the Figures 4 and 5 Tool combination 50 shown in a lateral sectional view. As described above, the leading chisel 20 is held on its chisel shank 24 by means of the clamping sleeve 25 so that it can rotate, but is axially blocked, in the leading chisel receptacle 42 of the chisel holder 40. The second trailing chisel 31 is fixed with its shank 37 both in the circumferential direction and axially blocked in the trailing chisel receptacle 46.2 of the second trailing attachment.

In the Figures 2 to 6 The tool combinations 50 shown, the leading chisel 20 and the respective trailing chisel 30, 31 are arranged to one another in such a way that with 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 Trailing chisel 30, 31 is thus arranged behind the leading chisel 20 in relation to the working movement 76 of the tool combination 50. As a result, the trailing chisel 30, 31 is arranged protected by the leading chisel 20.

The leading chisel 20 is dimensioned larger transversely to the working movement 76 than the trailing chisel 30, 31, so that it protrudes over this on both sides. As a result, the soil material removed by the leading chisel 20 is largely guided past the trailing chisel 30, 31. The leading chisel 20 and / or the wear protection disk 26 and / or the leading attachment 41 also covers the joining area between the trailing chisel 30, 31 and the trailing attachment 45, 46 of the bit holder 40 along the working movement 76. The joining area between the trailing chisel 30, 31 and the trailing shoulder 45, 46 of the chisel holder 40 is thus protected from high abrasive wear. This can reliably prevent the trailing attachment 45, 46 from being washed out and thereby exposing the joining surface between the trailing chisel 30, 31 and the trailing attachment 45, 46. This prevents the trailing chisel 30, 31 from being 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 from a super-hard material. The trailing chisel tip 32 is thus made harder in comparison 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 designed to be significantly more resistant to abrasive wear than the leading chisel tip 22 and thus the leading chisel 20. Combined with the protected arrangement of the trailing chisel 30, 31 described above, this has a significantly longer service life than the leading chisel 20. The service life of the trailing chisel 30, 31, with the appropriate design and arrangement of the trailing chisel 30, 31, is in the order of magnitude of the service life of the chisel holder 40. As a result, the trailing chisel 30, 31 cannot be interchangeably connected to the chisel holder 40, in particular it cannot be exchanged without being destroyed be connected to the chisel holder 40. On the other hand, the leading chisel 20, which is exposed to strong mechanical wear, is fastened to the chisel holder 40 such that it can be easily replaced. When the leading chisel 20 is worn, it can thus be easily replaced. Since the trailing chisel 30, 31 no longer needs to be exchanged due to its long service life, maintenance with corresponding downtimes of the soil cultivating machine 10 is only to be provided for the exchange of the leading chisel 20. As a result, the operating costs of the soil cultivating machine 10 can be kept low.

In the present case, the super-hard material is designed as a polycrystalline diamond. According to the present invention, it can be formed as a diamond material, as a diamond-reinforced material, as a silicon carbide material, as a cubic boron nitride or as a compound of at least two of the aforementioned materials. All of these materials or material combinations have a greater hardness than the hard metal from which the leading chisel is made, and thus a greater resistance to wear. In addition to the polycrystalline diamond, a monocrystalline diamond, chemically, can also be used as a diamond material deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, one or more successive diamond layers, thermally stable diamond or silicon-bonded diamond can be used.

During a milling process, the tool combination 50 is moved through the soil material to be removed due to the rotation of the milling drum 15 and the advance of the soil working machine 10. The trailing cutting edge 35 of the trailing chisel 30, 31 is arranged on a smaller radius 71 or the same radius as the leading cutting edge 23 of the leading chisel 20 in relation to the axis of rotation 15.1 of the milling drum 15. As a result, and due to the reduced geometry of the trailing chisel 30, 31 compared to the leading chisel 20, the leading chisel 20 cuts a larger volume than the trailing chisel 30, 31. According to the invention, the trailing chisel 30, 31 is designed and arranged to mill the leading chisel Chisel 20 to be reworked. In this case, in particular, the leading chisel 20 carries out a coarser milling and the trailing chisel 30, 31 carries out a finer milling. Accordingly, the trailing edge 32 of the trailing chisel 30, 31 is spatially arranged opposite the leading edge 23 of the leading chisel 20 that, given the operating parameters of the soil cultivating machine 10, each of the chisels 20, 30, 31 has a penetration depth into the soil material suitable for its task .

For example, a penetration depth of less than 15 mm for the trailing chisel 30, 31 is suitable for performing fine milling. Typical operating parameters of the soil cultivation machine 10 for such a milling process are a speed of the milling drum 15 of 130 revolutions / min, a feed speed of the soil cultivation machine 10 of 20 m / min and a milling depth of 100 mm. The larger cutting circle 70.1 of the leading edge 23 is, for example, approximately 980 mm. The milling depth of 100 mm and the larger cutting circle 70.1 results in a milling angle of 37.25 °, within which the chisels 20, 30, 31 in the case of a soil cultivating machine 10 operated with feed engage the soil material. From the engagement of the tool combination in the soil to its exit from the soil, the soil cultivating machine 10 moves approx. 15 mm forward. In order to obtain the desired fine finishing with the trailing chisel 30, 31, as it is suitable for performing fine milling, the smaller radius 71 on which the trailing cutting edge 35 of the trailing chisel 30, 31 is arranged must therefore be in the range at most less than 3 mm be selected as the larger radius 70 on which the leading edge 23 of the leading chisel 20 is arranged. Through the suitable arrangement of the trailing cutting edge 35 of the trailing chisel 30, 31 in relation to the leading cutting edge 23 of the leading chisel 20, the depth of penetration of the trailing chisel into the soil material can be determined and specified for given operating parameters of the soil tillage machine 10. This makes it possible for the leading chisel 20 to carry out a rough milling task, for example roughing, while the trailing chisel 30, 31 is designed for fine milling, for example finishing. The trailing chisel 30, 31 thus reworks the milling of the leading chisel 20. He thus determines the milling pattern obtained. Due to the very low wear of the trailing chisel 30, 31, this milling pattern remains at least largely the same even after a long period of use of the tool combination 50 and high wear of the leading chisel 20. If the leading chisel 20 wears to a certain extent, the trailing chisel 30 additionally takes over part of the work function of the leading chisel 20 while maintaining a milling pattern with a high surface quality.

It is also conceivable to design the system in such a way that, under the assumed machine parameters, the trailing chisel 30 has a cutting depth of 0 at the beginning of the work. Only when the leading chisel 20 begins to wear out does the trailing chisel 30 come into action and remove material. He then reworks the milling of the leading chisel 20, just as described above. This results in a perfect milling pattern again.

The leading chisel 20 is held in the leading chisel receptacle 42 of the chisel holder 40 such that it can rotate about its central longitudinal axis. When the leading chisel 20 engages in the removed soil material, it is rotated about its central longitudinal axis. As a result, the leading chisel 20 is worn evenly all round, which significantly extends its service life. The trailing chisel 30, 31, on the other hand, is not rotatably connected to the chisel holder 40. Due to the very great hardness of the trailing chisel tip 32, only insignificant wear of the trailing chisel 30, 31 occurs, so that no rotatable mounting of the trailing chisel 30, 31 is required. Due to the rigid connection of the trailing chisel 30, 31 with the chisel holder 40, vibrations in the trailing chisel tip 32 can be avoided. Such vibrations can lead to breakage of the super-hard material 34.

Claims (14)

1. Tool combination (50) comprising a chisel holder (40), which can be fastened to a milling drum (15) of a soil cultivating machine (10), and at least one leading and one trailing chisel (20, 30, 31), which are held on the chisel holder (40), wherein the trailing chisel (30, 31) being arranged behind the leading chisel (20) with respect to a working movement (76) of the tool combination (50) during use in the soil cultivating machine (10), and each chisel (20, 30, 31) having a chisel tip (22, 32) with a cutting edge (23, 35),
   characterized in
   that the trailing chisel tip (32) of the trailing chisel (30, 31) has, at least in regions, a greater hardness than the leading chisel tip (22) of the leading chisel (20),
   that the leading chisel (20) and the trailing chisel (30, 31) are designed and arranged on the chisel holder (40) in such a way that, in the case of a tool combination (50) mounted on a milling drum (15), the leading cutting edge (23) of the leading chisel tip (22) of the leading chisel (20) is arranged on a larger radius (70) relative to an axis of rotation (15. 1) of the milling drum (15) than the trailing cutting edge (35) of the trailing chisel tip (32) of the trailing chisel (30, 31) or in that the two cutting edges are arranged on substantially the same radii.
2. Tool combination (50) according to claim 1,
   characterized in
   that the trailing chisel tip (32) is formed, at least in regions, from a superhard material, in particular from a diamond material, a diamond-reinforced material, a silicon carbide material, from cubic boron nitride or from compounds of at least two of the aforementioned materials.
3. Tool combination (50) according to claim 2,
   characterized in
   that the diamond material is formed at least proportionally 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 layers 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 tungsten carbide, which is covered by the superhard material in the direction of the trailing cutting edge (35).
5. Tool combination (50) according to one of claims 2 to 4,
   characterized in
   that the superhard material is formed as a layer.
6. Tool combination (50) according to one of the claims 1 to 5,
   characterized in
   that the trailing chisel (30, 31) is connected to the chisel holder (40) in an axially and circumferential fixed manner and/or in that the leading chisel (20) is held axially and is connected to the chisel holder (40) in a rotatable manner in its circumferential direction.
7. Tool combination (50) according to one of claims 1 to 6,
   characterized in
   that the trailing chisel (30, 31) is not interchangeably connected to the chisel holder (40) and/or in that the leading chisel (20) is interchangeably connected to the chisel holder (40).
8. Tool combination (50) according to any one of claims 1 to 7,
   characterized in
   that the trailing chisel (30, 31) is formed from the trailing chisel tip (32), which is non-detachably connected, in particular soldered, directly to the chisel holder (40), and/or that the trailing chisel (30, 31) is formed at least from the trailing chisel tip (32) and a shank (37) connected indirectly or directly thereto, and in that the shank (37) is inserted in a trailing chisel receptacle (46. 2) of the chisel holder (40), preferably by means of a material-locking, a force-locking or a form-locking connection.
9. Tool combination (50) according to one of the claims 1 to 8,
   characterized in
   that the trailing chisel (30, 31) is designed and arranged to rework a milling operation carried out 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 than the leading chisel (20) from the material to be removed.
11. Tool combination (50) according to any one of claims 1 to 10,
    characterized in
    that the distance between the cutting edges (23, 35) of the leading chisel tip (20) and the trailing chisel tip (32) is between 45mm and 75mm, preferably between 50mm and 60mm, particularly preferably 54mm, and/or in that the radius (70, 71), on which the trailing cutting edge (35) of the trailing chisel tip (32) is arranged in a tool combination (50) mounted on a milling drum (15) is selected to be between 1 mm and 7 mm, preferably between 2 mm and 5 mm, particularly preferably 3 mm, smaller than the radius (70, 71) on which the leading cutting edge (23) of the leading chisel tip (22) is arranged.
12. Tool combination (50) according to any one of claims 1 to 11,
    characterized in
    that the trailing chisel (30, 31) is aligned at a smaller angle of attack (74) relative to a radial line (72) extending through the trailing cutting edge (35) than the leading chisel (20) is relative to a radial line (72) extending through the leading cutting edge (23), preferably in that the trailing chisel (30, 31) is aligned at an angle of attack between 25° and 35° and the leading chisel (20) is aligned at an angle of attack between 35° and 45° with respect to the respectively associated radial line (72).
13. A tool combination (50) according to any one of claims 1 to 12,
    characterized in
    that 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).
14. Tool combination (50) according to one of claims 1 to 13,
    characterized in
    that the leading chisel (20) projects beyond the trailing chisel (30, 31) transversely to the working movement (76) of the tool combination (50).

Images