EP3215330B1 - Tool system for a ground milling machine and ground milling machine comprising a tool system of this type - Google Patents

Description

The invention relates to a tool device for a ground milling machine, in particular a road milling machine, a recycler, a stabilizer or a surface miner, comprising a milling chisel with a highly wear-resistant chisel point, in particular comprising PCD material, and a chisel shank extending along a longitudinal axis, and a chisel holder with a shaft mount. The invention also relates to a milling tool and a change holder for such a tool device and a ground milling machine with a tool device according to the invention.

Such ground milling machines are usually used in road or path construction and in the mining of surface mineral resources. They usually include a machine frame or chassis, a driver's cab and several running gears. They also have a drive motor, which is usually a diesel engine, by which the ground milling machine, in particular its chassis and the working device, is driven. Such ground milling machines are, for example, from DE 10 2013 020 679 A1 and the DE 10 2013 002 639 A1 known to the applicant.

The working device of the ground milling machine is a milling drum, which is typically mounted in a milling drum box, which is closed at the sides and at the top and open at the bottom, so that it can rotate about its axis of rotation, which is mostly horizontal and transverse to the working direction. The milling drum is designed, for example, as a hollow cylinder and is equipped with a large number of tool devices on its outer surface. The tool devices each include, for example, a milling tool and a tool holder. The chisel holder is connected to the milling tube of the milling drum and carries the milling chisel. The chisel holder can, for example, be in one piece or alternatively also include several components, in particular a base holder and a change holder attached to the base holder, which in turn is designed to accommodate the milling tool. To build generic tool facilities is on the DE 10 2010 044 649 A1 and the DE 10 2010 051 048 A1 the applicant referred. Other chisel tools are, for example, from the writings US 4,299,424 B1 , CN 102518032A , US 5,374,111 B1 , U.S. 2012/080930 A1 , U.S. 2013/207445 A1 and U.S. 2009/200855 A1 known. When the ground milling machine is in operation, the tool devices are driven into the subsoil by the rotation of the milling drum and thus mill it open. If the ground milling machine moves in the working direction during milling, the soil subsoil material is milled along a milling track. Depending on the type of machine and the intended use, the loose milled material can then be transferred to a transport vehicle via a discharge belt and transported away (typically in the case of surface miners and road milling machines) or remain on the ground (typically in the case of stabilizers and recyclers).

During the milling process, the tool equipment, in particular the milling tool, is subject to heavy wear. The cutting bits of the tool devices therefore have to be replaced regularly. It also happens that the tool holders are either badly worn or damaged by a milling tool breaking. In this case, the chisel holder must also be replaced. In the case of chisel holders that include a basic holder and an interchangeable holder, it may be sufficient for the interchangeable holder to be replaced together with the milling tool.

In order to mount the cutting tool, it is known, for example, to fasten it rotatably in the tool holder. For this purpose, so-called clamping sleeves are then usually used. However, the rotatable mounting of the chisel in the chisel holder also has disadvantages. In addition to the increased use of material and the increased assembly effort, the rotation of the milling tool itself leads to increased wear between the tool shank and the clamping sleeve as well as between the wear plate and the holder. It is therefore also known to arrange the cutting tool in a rotationally fixed manner in or on the tool holder. For this purpose, the milling tool can be soldered directly onto the tool holder or be mounted in the tool holder with a press fit. Such a type of connection is often considered, for example, when the milling cutters used have materials with a comparatively high degree of hardness. The disadvantage of these design variants is that the changing process when the milling tool has reached its wear limit is relatively complex. It is then often necessary to exchange the chisel holder or the interchangeable holder together with the milling chisel as a coherent structural unit, even if actually only the milling tool is worn and needs to be replaced. In addition, the reassembly of the cutting tool requires a comparatively large amount of time and is correspondingly complicated. Especially when using soldered connections, the hardness or resistance of the material in the wear area is also reduced due to the temperature input into the chisel holder during soldering.

Against this background, it is the object of the present invention to specify a tool device of the generic type in which the assembly and the changing of the cutting tool are accelerated and simplified. It should be possible to exchange a milling tool without also having to exchange the tool holder or the interchangeable holder. The assembly of the milling tool in the tool holder should be quick and uncomplicated. In addition, the cutting tool should ideally be mounted in a rotationally fixed manner in the tool holder in the mounted state in such a way that it does not rotate about its longitudinal axis within the tool holder during milling operation.

The solution is achieved with a tool device, a milling tool, a change holder and a ground milling machine according to one of the independent claims. Preferred developments are specified in the dependent claims.

Specifically, the solution is achieved with a generic tool device in that the chisel shank of the milling chisel has at least one tapering section that narrows in the direction away from the chisel tip, that there is a fastening device that is designed in such a way that it secures the milling chisel along its longitudinal axis and in the direction of of the chisel point away into the shank receptacle, and that the shank receptacle of the chisel holder is at least partially designed to be complementary to the chisel shank of the milling chisel such that the tapered section rests at least partially in the shank receptacle in the chisel holder with a friction fit when clamped by the fastening device.

The chisel shank designates that part of the milling chisel that lies behind the chisel head that cuts the ground material in the tool feed direction. In contrast to the chisel head, which penetrates directly into the ground material and mills it open, the chisel shank is used to store and attach the milling chisel to the chisel holder. The chisel shank thus refers in particular to that part of the milling chisel which is located within the chisel holder in the assembled state or is guided into and partly also through the shank receptacle during assembly. It is not necessary for all parts of the chisel shank to be in direct contact with the chisel holder; it is rather sufficient if designated areas in contact with stand by the chisel holder. To assemble the cutting tool, the tool shank is guided into the shank receptacle of the tool holder, which typically represents an elongated, tunnel-like recess in the tool holder. The shank mount thus designates that part of the chisel holder which is used to hold and mount the chisel shank. Finally, the fastening device serves to fasten the chisel shank in the shank receptacle and thus the milling chisel itself in the chisel holder. According to the invention, the cutting tool bears directly against at least a partial area of the shank receptacle of the tool holder, in particular with the tapering section described below.

The milling chisel according to the invention has a chisel point and, at the end of the shank, a face opposite the chisel point and a longitudinal axis extending between these two ends of the milling chisel. The milling tool can, for example, be configured as a round-shank tool rotationally symmetrical about its longitudinal axis, although the invention also includes embodiments that are not necessarily rotationally symmetrical, for example with regard to the design of the tool tip. The taper section of the bit shank extends between a wide end and a narrow end. At the wide end, the chisel shank has a greater extent, at least in a direction radial to the longitudinal axis of the milling chisel, than at the narrow end. The tapering section is thus characterized in that the extent of the chisel shank decreases transversely to the longitudinal axis in this area away from the chisel tip in the direction of the shank end. The wide end is thus in the direction of the chisel tip, while the narrow end of the tapered area faces the end of the shank in comparison. The chisel shank thus narrows or tapers from the wide end of the tapered section towards the narrow end or in the “insertion direction” of the milling chisel into the shank receptacle. It is important that the chisel shank on the side of the tapered section facing away from the chisel tip no longer reaches the diameter or the cross-sectional area that it has at the wide end of the tapered section. As a result, the tapered section forms an insertion stop with which the chisel shank strikes the shank receptacle of the chisel holder when the milling chisel is pushed into the shank receptacle along its longitudinal axis.

The shank receptacle is shaped in such a way that it can at least partially accommodate the chisel shank as precisely as possible or in a form-fitting manner. The shank receptacle is a receiving opening, in particular a through-opening that completely penetrates the chisel holder, with the milling chisel in the assembled state having its narrowing section lying at least partially and in particular completely within the shank receptacle. The inventive design of the tapered portion, a stop area is formed in which the chisel shank with its narrowing section rests in a form-fitting manner on the inner wall of the shank receptacle and at the same time cannot be pushed any further into the shank receptacle. The chisel shank is shaped in such a way that it can be inserted from the outside into the shank receptacle up to the stop between the tapering section and the shank receptacle. In principle, it is possible for the diameter or the cross-sectional area of the chisel shank to increase again in the area adjoining the narrow end of the tapered section, even if not up to the diameter or cross-sectional area of the wide end of the tapered section. However, it is preferred if the diameter or the cross-sectional area of the chisel shank from the tapered section in the direction of the shank end does not exceed the diameter or the cross-sectional area of the narrow end of the tapered section. For example, a constant diameter cylindrical portion may be connected to the narrow end of the tapered portion.

The tapering section is in the form of a truncated cone, ie with side flanks running in a straight line in a plane along the longitudinal axis. This shape is comparatively easy to produce and has very good power transmission from the milling tool to the tool holder. In addition, with this shape, a particularly reliable and resilient frictional connection can be obtained between the tapered section of the chisel shank and the section within the chisel receptacle that is at least partially designed to complement it. It is further preferred if the chisel shank, in particular the tapered section, and the shank receptacle are designed in such a way that the milling chisel is centered by being mounted in the shank receptacle. A particularly stable attachment of the milling tool to the tool holder can be achieved by such a centering. This is achieved, for example, in that both the tapered section and the shank receptacle are designed to be rotationally symmetrical to the longitudinal axis of the milling tool, at least in the contact area of the tapered section.

The design of the cutting tool according to the invention and its attachment in the tool holder make it possible to attach the cutting tool in a particularly simple manner that can be installed quickly. In addition, it is advantageous that the chisel can be rotated after a certain period of use in order to slow down the progression of wear on the chisel. To do this, the chisel is loosened, turned and then fastened again so that it cannot rotate. In addition, no additional soldering of the cutting tool in the tool holder has to be carried out, which means that the material properties are not negatively influenced by excessive heating of the tool holder. At the same time, the contact of the tapered section with the shank receptacle results in a particularly reliable transmission of forces from the chisel holder to the milling chisel and vice versa. According to the invention, the cutting bit is clamped in the bit holder by the fastening device in such a way that it is locked in a non-rotatable manner in regular working operation by frictional engagement between the shank receptacle and the tapering section. In particular, this means that the milling tool does not rotate within the shank mount during operation. In the presently preferred case, highly wear-resistant chisel tips are used. A rotation of the cutting tool in the tool holder is not desirable for such cutting tools with tool tips comprising a highly wear-resistant material. In the present case, highly wear-resistant materials are, in particular, materials which have a Mohs hardness of at least 9.5, preferably at least 10. Such highly wear-resistant materials are therefore in particular boron nitride, tungsten carbide or other hard metals. A particularly suitable highly wear-resistant material is so-called PCD material (polycrystalline diamond, in particular with the designation "DP" according to ISO 513). PCD materials are characterized by the fact that they contain synthetically produced diamonds. These are usually randomly dispersed in a metal matrix that acts as a carrier material. Diamonds typically have a Mohs hardness of 10. The chisel points according to the invention are characterized in that they wear very little during operation compared to conventional chisel points and therefore achieve very long service lives. As an alternative to the Mohs hardness, the invention also extends to highly wear-resistant materials with a Vickers hardness according to DIN EN ISO 6507-1:2006-03 of at least HV 2400, preferably at least HV 4000, particularly preferably at least HV 6000, particularly preferably at least HV 8000, and very particularly preferably at least HV 10000. Alternatively, the relevant hardness test can also be carried out according to Knoop (DIN EN ISO 4545-1 to -4), with materials having hardnesses greater than 1300 and in particular greater than 4000 on the Knoop scale being used here according to the invention.

In the arrangement according to the invention, the forces introduced into the chisel tip are dissipated, in particular during milling operation, essentially via the tapered section or the contact surfaces between the tapered section and the bit holder. It is therefore particularly advantageous if this contact surface is particularly large. The tapered section is therefore preferably designed in relation to the entire chisel shank in such a way that the tapered section of the chisel shank extends at least over 25%, preferably at least over 50%, particularly preferably at least over 75% and very particularly preferably at least over 90% of the shank length, for example essentially over the entire length of the shaft. Accordingly, the shank receptacle is preferably designed to complement the chisel shank in such a way that the tapering section preferably rests against the shank receptacle over its entire length. A larger contact surface enables an advantageous distribution of forces and prevents the cutting tool from breaking out of the tool holder under extreme loads.

In principle, the tapered section of the chisel shank can be arranged at any point along the chisel shank. It is also possible, for example, for further tapered sections to be located in front of or behind the at least one tapered section along the longitudinal axis of the milling tool. However, in particular with regard to forces that act on the cutting tool perpendicular to the longitudinal axis of the cutting tool, it is particularly preferred if the narrowing section of the cutting tool shank is directly connected to the cutting tool head of the cutting tool. Since the tapered section then also rests directly behind the chisel head on the chisel holder or the shank receptacle of the chisel holder, forces acting on the milling chisel or on the chisel head, for example due to the collision of the milling chisel with the soil material to be milled, can be diverted directly behind the chisel head into the chisel holder. As a result, the milling tool sits particularly securely in the tool holder, even under extreme working conditions, and is stabilized by it. By contrast, bending moments acting on the chisel shank can be reduced by this arrangement or can be diverted particularly well into the chisel holder.

According to the invention, the chisel holder is a multi-part chisel holder, comprising an interchangeable holder and a basic holder. The basic holder has a holder receptacle for receiving the change holder and the change holder has the shank receptacle for receiving the chisel shank. With such a two-part bit holder, it is possible, for example, to exchange or renew only the milling bit and the quick-change tool holder, while the basic holder, which is usually protected from the abrasive attack of the milled material by the cutting tool and the quick-change tool holder, continues to be used. On the one hand, this saves material costs for the basic holders, which do not have to be replaced. On the other hand, it is also possible to add a mounting option for the milling tool and the interchangeable holder via the basic holder that enable faster assembly than welding a complete tool holder to the milling drum from scratch and then equipping it with a milling tool.

According to the invention, the milling tool and the interchangeable holder are both fastened to the basic holder at the same time via a single common fastening device. For this purpose, the fastening device is designed in such a way that it pulls and clamps both the milling chisel along its longitudinal axis and in the direction away from the chisel tip into the shank receptacle and the interchangeable holder into the holder receptacle in the basic holder. The fastening device thus fixes both the milling tool on the change holder and the change holder on the base holder. As a result, no separate fastening device has to be provided for the interchangeable holder. This significantly simplifies the structure of the tool device, lowers the manufacturing costs and reduces the assembly time.

In principle, the portion of the interchangeable holder provided for fastening could have any shape complementary to the holder receptacle. For example, it is conceivable that the interchangeable holder is secured against rotation in a form-fitting manner in the holder receptacle. However, it has been shown that a particularly favorable transmission of force in all directions from the interchangeable holder to the basic holder is made possible if the interchangeable holder is also in frictional contact with the basic holder. It is therefore preferred that the interchangeable holder bears against the base holder in a frictionally engaged manner and the milling tool bears against the interchangeable holder in a frictionally engaged manner. Both friction locks are now preferably achieved simultaneously by tightening the fastening device, which pulls the milling tool against the change holder and the change holder against the base holder.

In a specific embodiment of the invention it is therefore provided that the milling tool has a stop surface with which it rests on the interchangeable holder in the direction of insertion and that the interchangeable holder has a stop surface with which it rests on the base holder in the direction of insertion. A core idea of this preferred embodiment of the invention is now to design these contact surfaces as tapering sections. It is therefore preferred that both the milling tool and the quick change holder each have at least one tapered section, the tapered section of the cutting tool being in contact with the quick change holder and the tapered section of the quick change holder being in contact with the basic holder. In principle, everything that was stated above with regard to the tapering portion of the milling tool or the tool shank applies to the tapering portion of the quick-change holder. Due to the fact that both the milling tool and the quick-change holder have a tapering section and both the shank receptacle and the holder receptacle are complementary are formed to the respective tapering sections, the stop surfaces according to the invention are provided in a particularly simple and efficient manner.

Since the milling tool and the interchangeable holder are fastened by a single fastening device, it is advantageous if the milling tool and the interchangeable holder and the associated shank receptacle and the holder receptacle are designed in such a way that a form-fitting and friction-locking abutment between these components then comes about when the cutting tool and the toolholder are pulled in the same direction. This train can then be provided by only one fastening device. Structurally, this can be implemented in a particularly simple manner if the tapered sections of the milling tool and the quick-change holder narrow in the direction away from the tool tip or in the direction of insertion. The tapering sections of the milling tool and the change holder are thus aligned in the same way with regard to their wide and their narrow ends. The stops of the milling tool and the change holder on each other or on the base holder can be realized by pulling in the same direction.

The present invention allows the cutting tool to be exchanged separately from the tool holder. It should therefore not only be possible to assemble the tool device quickly and easily, but also to be able to disassemble a possibly worn milling tool or an interchangeable holder as simply and quickly as possible. In particular, it should be possible to detach the cutting tool from the tool holder as simply as possible and without the aid of special tools after loosening the fastening device and, if possible, not to dismantle the interchangeable tool holder from the basic holder as well. The tapered sections of the cutting tool and the quick change holder are therefore designed in relation to one another in such a way that the quick change holder, in particular after the fastening device has been loosened, has a greater expulsion force on the basic holder than the cutting tool on the quick change holder. This is achieved by the fact that the tapered sections of the milling tool and the quick change holder are in the shape of a truncated cone and the surface lines of the truncated cones each have an angle to the longitudinal axis of the cutting tool, and that the angle of the tapered section of the cutting tool is larger than the angle of the tapered section of the quick change holder. In particular, the truncated cone-shaped tapering sections of the milling tool and the quick-change holder are designed concentrically to one another. Due to the larger angle of the surface line of the frustoconical taper section of the milling tool compared to that of the interchangeable tool holder, the milling tool can be removed more easily from the interchangeable tool holder by pulling against the pulling direction of the fastening device, in particular along the longitudinal axis of the milling tool, than the interchangeable tool holder can be removed from the basic holder. If, after loosening the fastening device, such a train is exerted on the cutting tool, for example by a wedge or a flat chisel between the chisel head and the chisel holder, it slips out of the shank mount and can be removed. On the other hand, removing the quick change holder requires a higher pull, which makes it possible to easily leave the quick change holder in its installed position in the basic holder even after loosening the fastening device and to fix it again by installing a new milling tool by attaching the fastening device .

How much easier it should be to dismantle the cutting tool compared to dismantling the quick-change holder is largely determined by the difference between the respective angles of the generatrices of the frustoconical tapering sections and the longitudinal axis of the cutting tool, as well as the size of the contact surfaces. The greater the difference, the easier it is dismantle the milling tool compared to the quick-change holder. Provision is therefore made for the angle of the tapered section of the milling tool to the longitudinal axis to be at least 0.2° greater than the angle of the tapered section of the interchangeable holder to the longitudinal axis. On the one hand, this angle range has proven to be particularly stable and, on the other hand, particularly advantageous for the separate dismantling of the milling tool and the quick-change holder.

As already mentioned, the milling chisel can be removed from the shank receptacle of the interchangeable holder or the chisel holder, for example by pulling on the chisel head. A flat chisel can be used for this purpose, for example, which is inserted between the chisel head and the chisel holder and with the aid of which the milling chisel can then be levered out of the shank mount. Alternatively, the milling chisel can be pushed out of the shank receptacle from its end face opposite the chisel tip. In order to achieve this, it is preferable for the shank receptacle and the holder receptacle to have an opening on their end faces opposite the chisel tip, with the openings being formed one behind the other, and for the milling chisel to pass through both the opening of the quick-change holder and the opening of the Basic holder is performed. The end of the shank or the end face of the milling chisel, which is opposite the chisel tip, can therefore be reached through the opening in the basic holder and the opening in the interchangeable holder. Here, for example, a tool can be introduced with which pressure can be exerted on the cutting tool in order to drive it out of the tool holder.

In principle, the milling tool can be driven out by inserting a tool through the openings in the basic holder and the interchangeable holder. However, in order to further facilitate the dismantling of a worn chisel, it is preferred that no special tool is required for driving out the milling chisel. For this it is advantageous if the milling tool protrudes with its shank end opposite the chisel tip out of the opening of the basic holder beyond the latter. In the assembled state of the milling tool, its shank end protrudes from the tool holder. This makes it possible to drive out the milling tool by hitting the end of the shank directly with an ordinary hammer. A special tool for changing the cutting tool, such as a drift, is then no longer necessary.

However, it may be the case that, for example, there is very little space in the area in which the shank end of the milling tool protrudes from the tool holder. It is therefore preferable to remove the cutting bits from the bit holder from the side of the bit head. The cutting tool can be disassembled from the tool holder in a particularly simple manner with the fastening device released by inserting a tool, for example a wedge or a flat chisel, between the tool head and the tool holder and by levering the cutting tool out of the tool holder. In order to be able to introduce such a tool, a gap is provided between the chisel head and the chisel holder. In principle, the intermediate space can arise, for example, in that the chisel head does not rest directly on the chisel holder when the tool device is in the installed state, but is spaced apart from it by a free space when viewed in the longitudinal direction. However, it is preferred if the chisel head rests at least partially on the chisel holder with its rear side opposite the chisel point. This results in a further, advantageous transmission of force from the milling tool to the tool holder via the contacting surfaces. In addition, a drive-out recess is now preferably provided between the chisel head and the chisel holder, in the region of which the chisel head is at a distance from the chisel holder, as a result of which the intermediate space is created and into which a tool can be inserted. Overall, it is therefore preferred if the tool device has a drive-out recess that is created in such a way that when the tool device is installed, there is a gap between the chisel head and an end face of the chisel holder opposite the back of the chisel head. Dismantling is particularly quick and easy by levering out the cutting tool using a tool inserted into the gap. At the same time, however, it is preferably provided if the chisel head rests at least partially on the end face of the chisel holder.

In principle, the drive-out recess can be designed in any way, so that a tool for levering out the cutting tool can be guided between the tool head and the tool holder. The expulsion recess can be designed, for example, as a notch, with round or flat side walls. However, the expulsion recess is particularly easy to produce as a bevel or chamfer. The chamfer does not have to cover the entire annular surface of the tool holder and/or run around the back of the chisel head; it is sufficient to provide such a drive-out recess at least at one point. It can be located either on the chisel head or on the chisel holder or on both parts. It is particularly preferred that the drive-out recess on the rear side of the chisel head is designed as a slope, in particular as a slope with an angle relative to a perpendicular to the longitudinal axis of the milling tool in the range from 15° to 25°, preferably in the range from 18° to 22° and particularly preferred of 20°. Alternatively, the expulsion recess is designed as a notch. Changing the cutting tool is made much easier and faster by the embodiment described. The drive-out recess is particularly preferably in two parts, with two partial recesses lying opposite one another with respect to the longitudinal axis of the chisel, the two partial recesses being very particularly preferably mirror-symmetrical to one another.

The fastening device for the cutting tool or the cutting tool and the interchangeable holder can in principle be designed in different ways. In one embodiment, the fastening device is a pulling device that is able to exert a pulling force on the cutting tool and thereby clamp the cutting tool in the shank mount. The fastening device thus clamps the cutting tool in the change holder or in the tool holder and holds it there. This can be implemented particularly easily if the fastening device comprises a screw connection. In principle, the fastening device can be arranged on any section of the chisel shank. However, it is particularly easy to pull on the cutting tool if the fastening device is arranged on the end of the cutting tool opposite the cutting tool tip, ie the end of the shank. It is therefore preferred that the milling chisel has a fastening section with an external thread at the shank end opposite the chisel tip, and that the fastening device is a nut, in particular a self-locking nut, which is screwed onto the fastening section against the chisel holder. The train is created by screwing the nut against the bit holder; the chisel shank of the milling chisel then acts as a tie rod. The tightening torque of the fastening device is in the range of 100 Nm, for example. This pulls the cutting tool into the shank mount, through the opening in the quick-change holder and through the opening in the basic holder to the fastening device. The milling chisel is braced in the shank receptacle by the taper section of the chisel shank striking the shank receptacle. The nut is attached using standard tools from the rear of the toolholder. Since the fastening section of the milling tool, which carries the external thread, protrudes at least partially out of the opening in the base holder and protrudes beyond the base holder, this is External thread particularly easy to reach for mounting the fastening device. In principle, the nut can be secured against creeping loosening during operation by any of the possibilities known in the prior art, for example by countering with another nut or by using a castellated nut. However, it is preferred if the nut is a self-locking nut with a plastic ring. Overall, the fastening device according to the invention can be used to quickly, easily and simply attach and detach the fastening device, as a result of which the assembly and disassembly of the milling tool can be accelerated.

The wear of the cutting bits or the tool devices of the prior art is often accelerated in that severely crushed milled material and/or water penetrates with the milled material between the chisel shank and the chisel holder, where it leads to increased wear due to abrasion. In order to avoid this, it is preferred that a sealing washer is present, which is clamped between the nut and the chisel holder and which seals off the shank receptacle of the chisel holder from the outside. In this case, the sealing disc can be, for example, a conventional elastic plastic seal. The provision of the sealing disk prevents water and/or milled material from penetrating the holder receptacle and/or the shank receptacle of the chisel holder via the opening in the basic holder. Overall, this measure also serves to extend the service life of the tool device.

The present invention is particularly suitable for non-rotating milling cutters with a highly wear-resistant cutter tip. In order to minimize wear on the chisel head even further, it is provided that those parts and/or sides of the chisel head that have abrasive contact with milled material during operation are provided at least partially and in particular completely with a protective layer made of low-wear material. This protective layer is made of tungsten carbide and surrounds the chisel head in the form of a cap. By shaping the protective layer as a cap, a particularly effective wear protection layer can be formed, with comparatively little expensive hard metal having to be used to produce the cap. It is therefore provided that the milling chisel has a wear protection cap made of tungsten carbide, the chisel point being fastened to the wear protection cap by brazing and the wear protection cap being brazed to the base body of the milling chisel. The protected base body can then consist, for example, of steel or a similar material. The soldering temperature is preferably below 660° C. in order not to have a negative impact on the material properties of the base body of the milling tool. In particular is it is preferred that the tool device according to the invention has a wear protection, as in the DE 10 2014 014 094.6 is described by the applicant. Reference is hereby made to this document for protection against wear. By providing such a wear protection cap on the cutting tool according to the invention, the service life of the tool device can be increased even further, as a result of which the efficiency of the tool device increases overall.

In principle, rotation of the cutting tool during operation is reliably prevented by the frictional connection according to the invention between the cutting tool and the tool holder. In order to reliably and permanently prevent the chisel from rotating in the shank mount even under the most extreme working conditions, it is advantageous if the milling chisel and the chisel holder are designed in such a way that there is a positive-locking device to prevent rotation between the milling chisel and the bit holder, which is designed in this way that it prevents rotation of the cutting tool in the tool holder about its longitudinal axis. Via the form fit, such forces can thus preferably be reliably derived from the milling tool into the tool holder, which would lead to a rotation of the milling tool. Correspondingly, the positive locking device is preferably designed in such a way that a positive locking between the cutting tool and the tool holder is made possible in the circumferential direction to the longitudinal axis of the cutting tool, ideally in both possible directions of rotation.

Such a form fit can be achieved via a large number of possible specific shapes between the milling tool and the tool holder. For example, the chisel shank, and complementary thereto also the shank receptacle, can be oval or polygonal, in particular in cross section perpendicular to the longitudinal axis. It is then no longer possible to rotate the milling tool in the shank mount. However, it is easier to produce structures on the milling tool and on the tool holder that engage in one another, particularly in the direction of the longitudinal axis and not around it. It is therefore preferred that there is a recess on the bit holder and a projection on the milling bit, or vice versa, with the recess and the projection being created to complement one another in such a way that when the tool device is in the installed state they engage in one another in a form-fitting manner and rotation of the milling bit in the bit holder is reversed prevent its longitudinal axis. For example, the projection can have a pin or a tooth-like structure. For example, the projection could also have the shape of a crown wheel.

It is possible to provide the projection on the cutting tool and the recess on the tool holder, and vice versa. Also, the protrusion and the recess can be located anywhere as long as they do not interfere with the mounting of the cutting tool on the tool holder. So it is conceivable, for example, the projection or the recess on the chisel shank and to be provided in the socket. The projection or the recess can also be provided on the chisel head, in particular on the wear protection cap of the chisel head. The design of the wear protection cap has the advantage that it consists of hard metal and the form-fit elements wear particularly little as a result, whereby the form-fit can be guaranteed for the entire service life of the milling tool. A particularly preferred embodiment has been found when the recess is formed on the annular surface of the bit holder opposite the back of the bit head and the projection is formed on the back of the bit head, in particular in one piece with a wear protection cap. Here, a fitter can see the elements particularly well and attach the cutting tool to the tool holder particularly easily.

A projection and a recess complementary thereto are sufficient to obtain an extremely resilient and reliable anti-twist protection for the milling tool. However, a particularly reliable protection against rotation is achieved when there are a number of projections or recesses. There can also be several drive-out recesses. There are also several gaps for levering out the cutting tool. In this case, the projections or recesses are preferably arranged alternately with the drive-out recesses in the circumferential direction of the chisel shank or the chisel head. It can thereby be ensured that the forces acting on the cutting tool, which would lead to the cutting tool rotating in the tool holder without an anti-twist device, are reliably dissipated.

It is particularly advantageous if the projections or the recesses and the drive-out recesses are arranged in such a way that the milling tool can be mounted in different rotational positions (with respect to a rotation about its longitudinal axis) in the tool holder in the same way. Equivalent here means that with every possible assembly of the milling tool in a rotational position, the same arrangement of projections, recesses and drive-out recesses is present in the tool device as in all other rotational positions of the milling tool. In other words, it is preferred that the projections or recesses and the drive-out recesses are arranged symmetrically in such a way that the milling tool can be mounted rotated by 90°, particularly preferably by 180°, without changing the configuration of the projections or recesses and the drive-out recesses in the change tool setup. In addition, smaller angular ranges are also conceivable. This configuration of the tool device makes it possible to dismantle the milling tool after a certain period of use in order to rotate it by an appropriate angle, for example 90° or 180° to be mounted again on the chisel holder. Asymmetrical, and therefore faster, wear can be avoided in this way, which increases the service life of the milling tool.

The object of the invention mentioned at the outset is also achieved with a milling tool and/or with an interchangeable holder for a tool device as described above. All of the described features and advantages of the milling tool or the quick-change holder apply accordingly.

The solution is also achieved with a ground milling machine with a tool device as described above. The ground milling machine, which can in particular be a road construction machine of the road milling, recycler or stabilizer type or a surface miner, preferably has a multiplicity of the tool devices described above mounted on its milling drum.

Figur 1

eine Seitenansicht einer Bodenfräsmaschine;

Figur 2

eine perspektivische Ansicht einer Werkzeugeinrichtung von schräg rechts vorne;

Figur 3

eine Explosionsdarstellung einer Werkzeugeinrichtung;

Figur 4

einen Längsschnitt durch eine Werkzeugeinrichtung;

Figur 5

einen Längsschnitt durch eine weitere Werkzeugeinrichtung;

Figur 6

einen Längsschnitt durch eine Werkzeugeinrichtung beim Lösen des Fräsmeißels;

Figur 7

eine perspektivische Ansicht eines Fräsmeißels von schräg hinten;

Figur 8

eine perspektivische Ansicht einer Werkzeugeinrichtung mit teilweise gelöstem Fräsmeißel von schräg rechts vorne; und

Figur 9

eine perspektivische Ansicht einer Werkzeugeinrichtung mit teilweise gelöstem Fräsmeißel von schräg links hinten.

The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the figures. They show schematically:

figure 1

a side view of a ground milling machine;

figure 2

a perspective view of a tool device diagonally from the right front;

figure 3

an exploded view of a tool device;

figure 4

a longitudinal section through a tool device;

figure 5

a longitudinal section through another tool device;

figure 6

a longitudinal section through a tool device when releasing the cutting tool;

figure 7

a perspective view of a cutting tool obliquely from behind;

figure 8

a perspective view of a tool device with a partially detached cutting tool diagonally from the right front; and

figure 9

a perspective view of a tool device with a partially detached milling tool from diagonally left behind.

Identical components are provided with the same reference symbols. Repeating components are not separately identified in all figures.

figure 1 shows a ground milling machine 1, here a road milling machine of the type cold milling machine with a central rotor. The ground milling machine 1 comprises a driver's cab 2 with a driver's seat and a control panel, a machine frame 3 and a drive motor 4. The drive motor 4, for example a diesel engine, drives the driving devices 6, the milling drum 9 and the discharge belt 5, among other things. The milling drum 9 is rotatably mounted in the milling drum box 7 about an axis of rotation 10 running horizontally and transversely to the working direction a. During operation of the ground milling machine 1, the milling drum 9 mills the ground 8 in the working direction a. Loose milled material is transferred via the discharge belt 5 to a transport vehicle (not shown) and transported away by it.

For milling the ground 8, the milling drum 9 is equipped with tool devices 11, one of which is shown in perspective in figure 2 is shown. The tool device 11 comprises a milling tool 14 and a tool holder 29. In the exemplary embodiment shown, the tool holder 29 is constructed in two parts and includes a basic holder 12 connected to the milling tube of the milling drum and an interchangeable holder 13. The basic holder 12 is attached to the milling tube of the milling drum via its base 15 9 welded on. It is also possible to fasten the base holder 12 with its base 15 on a pedestal (not shown) or a segment of another supporting structure, the pedestal or the supporting structure in turn being fastened to the milling tube, for example welded on. It is essential that the base holder 12 is connected directly or indirectly to the milling tube via its foot end 15 . The change holder 13 fastened to the base holder 12 has a projection designed as a chip breaker 16 which is used in operation to crush clods of milled material and to guide milled material past the chisel holder 29 . In addition, in the area of the chip breaker 16 the quick change holder 13 positively engages in an undercut of the basic holder 12 and thus contributes to a positive force dissipation, in particular of forces which are directed perpendicularly to the longitudinal axis of the milling tool 14 . The cutting tool 14 is partially accommodated in the tool holder 29 and is held in place in this by the fastening device 19 , here a self-locking nut, as a result of which the cutting tool 14 is fixed to the milling drum 9 by the tool holder 29 .

The structure of the cutting tool 14 is further evident from the Figures 3 and 4 . figure 3 shows the cutting tool 14 in a side view, while the figure 4 shows a longitudinal sectional side view through the cutting tool 14 mounted in the tool holder 29 along the longitudinal axis 35 of the cutting tool 3 is. The milling tool 14 comprises a chisel head 40 and a shank 20. The chisel head 40 in turn comprises a chisel tip 17 with PCD material and a wear protection cap 18 made of hard metal, here tungsten carbide. In the area in which the chisel head 40 covers the chisel holder 29 or the interchangeable holder 13, the milling chisel 14 can either be placed directly on the shank mount 26 rest on the annular surface 27 surrounding it or be slightly spaced from it, without there being direct contact between the annular surface 27 and the chisel head 40, as in Figures 4 and 5 shown. In this area there is then an intermediate space 33, which will be described in more detail below.

As in particular from the sectional view according to figure 4 shows, the wear protection cap 18 surrounds a base body 31 of the cutting tool 14 in the area of the chisel head 40. By designing the wear protection cap 18 as a cap, a high wear resistance of the chisel is achieved on the one hand and hard metal material is saved on the other. The chisel point 17 is fastened to the wear protection cap 18 at a soldering point 28 by brazing. The wear protection cap 18 is in turn fastened to the base body 31 of the milling tool 14 by hard soldering at a further soldering point 28 . Overall, the milling tool 14 extends along the longitudinal axis 35. In the exemplary embodiment shown, the milling tool 14 is rotationally symmetrical about the longitudinal axis 35. The chisel shank 20 is that part of the milling chisel 14 which directly adjoins the chisel head 40 opposite the chisel tip 17 . The chisel shank 20 is formed in one piece with the base body 31 of the milling chisel 14 and consists, for example, of heat-treated steel, in particular 42CrMo4. Overall, the chisel shank 20 thus forms a tie rod with a tensile strength of at least 800 N/mm ² .

The shank 20 is used to attach the cutting tool 14 to the chisel holder 29, while the chisel head 40 is used to cut open and crush the soil material. For this purpose, the chisel shank 20 has a shank length 34 along the longitudinal axis 35 of the milling chisel 14 which comprises a plurality of sections of the chisel shank 20 . Thus, the chisel shank 20 has a tapered section 23 , a cylindrical section 22 and a fastening section 21 . The tapered section 23 directly adjoins the chisel head 40 on the rear side 47 of the chisel head 40 opposite the chisel tip 17 . It is characterized in that it becomes narrower from the side directed towards the chisel head 40 in the direction of the shank end 43 in relation to its cross section transverse to the longitudinal axis. In the tapered section 23 the diameter or the cross-sectional area of the chisel shank 20 decreases along the longitudinal axis 35 in the direction of the shank end 43 . In the exemplary embodiment shown, the tapering section 23 is in the shape of a truncated cone and does not extend over the entire length of the shank 34; At the shank end 43 there is also a substantially cylindrical fastening section 21 with an external thread, which is used to fasten the milling tool 14 in the tool holder 29, as will be described in detail below.

The attachment of the cutting tool 14 in the tool holder 29 is in particular from a synopsis of Figures 3 and 4 out. The chisel holder 29 has a shank receptacle 26 which is designed to complement the shape of the chisel shank 20 . In the exemplary embodiment shown, this means that the shank receptacle 26 also has a tapered section 39 and a cylindrical section 38 . The tapered section 39 of the shank receptacle 26 is designed in particular in such a way that the outer surface of the frustoconical tapered section 23 of the chisel shank 20 rests over its entire surface on the inner wall of the shank receptacle 26 in the tapered section 39 as soon as the milling tool 14 is mounted in the tool holder 29. The shank receptacle 26 runs through the entire chisel holder 29, including the interchangeable holder 13 and the basic holder 12. The shank end 43 and at least partially the fastening section 21 of the chisel shank 20 project out of the chisel holder 29 at the end of the chisel holder 29 opposite the chisel tip 17 . For this, the chisel shank 20 is guided through an opening 32 in the quick-change holder 13 and an opening 41 in the basic holder 12 . A fastening device 19 , here a self-locking nut, is screwed onto the external thread of the fastening section 21 and is screwed against the chisel holder 29 via a sealing disk 25 . By firmly tightening the fastening device 19, a train is exerted on the cutting tool 14, which pulls the cutting tool 14 into the shank receptacle 26 of the tool holder 29. The pull of the fastening device 19 is so strong that the cutting tool 14 with the tapered section 23 of the tool shank 20 rests frictionally on the tapered section 39 of the shank receptacle 26 and is particularly stationary during working operation, i.e. does not rotate or is non-rotatable during milling operation.

Out of figure 4 shows that the fastening device 19 for the cutting tool 14 according to the present invention is used in a two-part tool holder 29 to attach both the cutting tool 14 to the change holder 13 and the change holder 13 to the base holder 12 . For this purpose, the basic holder 12 has a holder receptacle 37 which is designed to complement a tapering section 36 of the interchangeable holder 13 . The tapering section 36 of the tool holder 13 also narrows in the pulling direction of the fastening device 19, analogously to the tapering section 23 of the chisel shank 20. According to the present invention, the tapering section 36 of the tool holder 13 is also designed in the shape of a truncated cone. The pull of the fastening device 19 pulls the interchangeable holder 13 into the holder receptacle 37 , the narrowing section 36 of the interchangeable holder 13 resting against the inner wall of the holder receptacle 37 with a friction fit. A further anti-twist protection of the change holder 13 relative to the base holder 12 is achieved in that the change holder 13 engages in an undercut of the base holder 12 in the area of the chip breaker 16 .

Overall, therefore, for the assembly of the tool device 11 according to the figures 2 , 3 and 4 the base holder 12 is welded onto the milling drum 9. Then the exchange holder 13 is inserted into the holder receptacle 37 and the milling tool 14 is inserted into the shank receptacle 26 until the attachment section 21 of the chisel shaft 20 protrudes from the rear opening 41 of the basic holder 12 . The fastening device 19 and the sealing disk 25 are then screwed onto the fastening section 21 or its external thread. By screwing the fastening device 19 against the chisel holder 29, all the components of the tool device 11 are fastened to one another. To remove a worn cutting tool 14, the fastening device 19 must be loosened. The milling tool 14 can then be driven out of the tool holder 29 by hitting the protruding fastening section 21 on the shaft end 43 with a simple hammer. In order to ensure that the cutting tool 14 is driven out of the shank receptacle 26 without the quick-change holder 13 also being released from the holder receptacle 37, the angle α of a surface line of the frustoconical tapering section 23 of the chisel shank 20 to the longitudinal axis 35 of the cutting tool 14 is greater than the angle β a generatrice of the frustoconical tapering section 36 of the change holder 13 to the longitudinal axis 35. As a result, the expulsion force of the cutting tool 14 in the change holder 13 is smaller than the expulsion force of the change holder 13 in the base holder 12 figure 5 The auxiliary line indicated to represent the angle α is parallel to the longitudinal axis 35 of the milling tool 14. Since the angle α of the milling tool is larger than the angle β of the quick-change holder 13, only the milling tool 14 comes loose from the shaft end 43 when the shaft end 43 is hit Shank receptacle 26, while the change holder 13 remains in the holder receptacle 37. If you also want to replace the interchangeable holder 13, the ejection opening 30 in the base holder 12 can be used for this purpose, through which, for example, a suitable tool can be inserted into the base holder 12, with which the interchangeable holder 13 can be driven out of the holder receptacle 37.

figure 5 Fig. 1 shows a tool device 11 with a one-piece bit holder 29 (This embodiment is outside the scope of protection defined by claim 1). Of the
Bit holder 29 also holds the milling bit 14 here and is welded directly onto the milling drum 9 or welded to the milling drum tube via a pedestal or a segment of a support structure. Except for the division into change holder 13 and basic holder 12, all the above explanations also apply to the tool device 11 according to FIG figure 5 . In particular, the shank receptacle 26 of the chisel holder 29 corresponds to FIG figure 5 the shank receptacle 26 of the change holder 13. Also the one-piece chisel holder 29 according to figure 5 has an opening 42 from which the cutting tool 14 exits at the end opposite the chisel tip 17 .

An alternative way to disassemble the cutting tool 14 from the tool holder 29 is in particular from the Figures 6 and 7 out. figure 7 shows an embodiment of a cutting tool 14 in which two expulsion recesses 24 are provided on the rear side 47 of the chisel head 40, ie that side of the chisel head 40 which is opposite the chisel tip 17. The drive-out recesses 24 are designed as inclined surfaces or chamfers, which in the example shown form an angle γ ( 6 ) of 20° relative to a perpendicular to the longitudinal axis 35 of the milling tool 14 . Like in particular figure 6 As can be seen, the drive-out recesses 24 form an intermediate space 33 between the chisel head 40 and the annular surface 27 of the chisel holder 29. If the fastening device 19, as in FIG figure 6 shown, is released, a fitter can insert a tool, for example a flat chisel 44, into the space 33 and use it as a lever to remove the milling chisel 14 from the chisel holder 29 or the change holder 13. The arrangement of several drive-out recesses 24 in the circumferential direction of the chisel shank 20 or the chisel head 40 has the advantage that the milling chisel 14 can be mounted in any rotational position (relative to a rotation about its longitudinal axis 35) in the chisel holder 29, and yet it is always easy for a fitter Access to at least one expulsion recess 24 has.

In the Figures 8 and 9 a further embodiment is shown, in which the tool device 11 has an anti-rotation device which prevents the milling tool 14 from rotating about the longitudinal axis 35 . In concrete terms, the milling tool 14 has two opposing projections 46 on the rear side 47 of the tool head 40 , which are designed to complement two recesses 45 present on the ring surface 27 of the tool holder 29 or the change holder 13 . The two projections 46 and the recesses 45 are formed opposite to each other. In particular, they are arranged symmetrically with respect to the longitudinal axis 35 . If the milling tool 14 is inserted into the tool holder 29, the projections 46 engage in the recesses 45 in a form-fitting manner. This prevents the milling tool 14 from rotating about its longitudinal axis 35 .

The cutting tool 14 of the embodiment of Figures 8 and 9 also have drive-out recesses 24 in the form of bevels. The drive-out recesses 24 are also formed opposite one another on the rear side 47 of the chisel head 40 and, in particular, are arranged symmetrically with respect to the longitudinal axis 35 . Drive-out recesses 24 and projections 46 alternate with respect to the circumferential direction of the rear side 47 of the chisel head 40 . The tool device 11 is designed in such a way that the milling tool 14 can be mounted in two different positions on the tool holder 29 . Specifically, the milling tool 14 can be rotated through 180° and mounted on the tool holder 29 in this position. Through the symmetrical Formation of the projections 46 and recesses 45, as well as the drive-out recesses 24, the installation situation is then the same as before the milling tool 14 was rotated. This means that both the anti-rotation device engages in a form-fitting manner and at least one drive-out recess 24 is easily accessible for a fitter and is easy to reach. In this way, the milling tool 14 can be disassembled after a certain period of use and rotated through 180° and reassembled in order to make its wear even and thereby slow it down.

Overall, the tool device 11 according to the invention has an increased service life of the cutting tool 14, with the assembly of the cutting tool 14 and the interchangeable holder 13 on the basic holder 12 being particularly easy and quick, which also means that work breaks to replace worn cutting tools 14 or interchangeable holders 13 can be minimized. The total number of components of the chiseling device 11 can also be reduced through the use of a common fastening device 19 for fastening the milling chisel 14 and the interchangeable holder 13, and further costs can thus be saved.

Claims (13)

1. A tool device (11) for a ground milling machine (1), particularly a road milling machine, a recycler, a stabilizer or a surface miner, comprising

   - a milling chisel (14) having a highly wear-resistant chisel tip (17), particularly comprising PCD material, and a chisel shaft (20) extending along a longitudinal axis (35), and

   - a chisel holder (29) with a shaft receptacle (26),

   - the chisel shaft (20) of the milling chisel (14) has at least one tapering section (23) narrowing in a direction away from the chisel tip (17),

   - a fastening device (19) is provided, which is designed in such a way that it pulls the milling chisel (14) along its longitudinal axis (35) and in the direction away from the chisel tip (17) into the shaft receptacle (26),

   - the shaft receptacle (26) of the chisel holder (29) is designed complementary to the chisel shaft (20) of the milling chisel (14) in such a way that the tapering section (23), when braced by the fastening device (19), at least partly bears against the chisel holder (29) in the shaft receptacle (26) in a frictionally locking manner,

   - the chisel holder (29) comprises a base holder (12) and a quick-change chisel holder (13), the base holder (12) comprising a holder receptacle (37) for receiving the quick-change chisel holder (13), and the quick-change chisel holder (13) comprising the shaft receptacle (26), and

   - the fastening device (19) is designed in such a way that it pulls both the milling chisel (14) along its longitudinal axis (35) and in the direction away from the chisel tip (17) into the shaft receptacle (26) and the quick-change chisel holder (13) into the holder receptacle (37) in the base holder (12),
   characterized in that

   - the milling chisel (14) has a wear protection cap (18) made of tungsten carbide, the chisel tip (17) being attached to the wear protection cap (18) by means of hard-soldering, and the wear protection cap (18) being attached to the milling chisel (14) by means of hard-soldering,

   - the milling chisel (14) and the quick-change chisel holder (13) each have at least one tapering section (23, 36), the tapering section (23) of the milling chisel (14) bearing against the quick-change chisel holder (13), and the tapering section (36) of the quick-change chisel holder (13) bearing against the base holder (12), the tapering sections (23, 36) of the milling chisel (14) and the quick-change chisel holder (13) narrowing in particular in the direction away from the chisel tip (17), and

   - the tapering sections (23, 36) of the milling chisel (14) and the quick-change chisel holder (13) are shaped as truncated cones and the surface lines of the truncated cones each have an angle (α, β) relative to the longitudinal axis (35) of the milling chisel (14), and that the angle (α) of the tapering section (23) of the milling chisel (14) is larger than the angle (β) of the tapering section (36) of quick-change chisel holder (13), the angle (α) of the tapering section (23) of the milling chisel (14) relative to the longitudinal axis (35) being greater by at least 0.2 ° than the angle (β) of the tapering section (36) of the quick-change chisel holder (13) relative to the longitudinal axis (35).
2. The tool device (11) according to claim 1,
   characterized in that
   the chisel tip (17) comprises a material with a Vickers hardness according to DIN EN ISO 6507-1:2006-03 of at least HV 2400, preferably at least HV 4000, more preferably at least HV 6000, more preferably at least HV 8000, and most preferably at least HV 10000.
3. The tool device (11) according to any one of the preceding claims,
   characterized in that
   the tapering section (23) of the chisel shaft (20) extends over at least 25 %, preferably over at least 50 %, more preferably over at least 75 %, and most preferably over at least 90 % of the shaft length (34), for example, essentially over the entire shaft length (34).
4. Tool device (11) according to any one of the preceding claims,
   characterized in that
   the milling chisel (14) has a chisel head (40), and that the tapering section (23) of the chisel shaft (20) directly adjoins the chisel head (40).
5. The tool device (11) according to any one of the preceding claims,
   characterized in that

   the quick-change chisel holder (13) bears against the base holder (12) in a frictionally locking manner and/or

   the angle (α) of the tapering section (23) of the milling chisel (14) relative to the longitudinal axis (35) being greater by up to 2 °, and more preferably by 0.8 ° than the angle (β) of the tapering section (36) of the quick-change chisel holder (13) relative to the longitudinal axis (35).
6. The tool device (11) according to any one of the preceding claims,
   characterized in that
   the shaft receptacle (26) and the holder receptacle (37) each have an opening (32, 41) on their face sides opposite the chisel tip (17), the openings (32, 41) being positioned one behind the other, and that the milling chisel (14) is guided through both the opening (32) of the quick-change chisel holder (13) as well as through the opening (41) of the base holder (12), the milling chisel (14), with its shaft end (43) opposite the chisel tip (17), in particular projecting out of the opening (41) of the base holder (12) and beyond the latter.
7. The tool device (11) according to any one of the preceding claims,
   characterized in that
   it has an expulsion recess (24), which is made in such a way that, when the tool device (11) is assembled, there is a clearance (33) between the chisel head (40) and a face side (27) of the chisel holder (29) opposite the backside (47) of the chisel head (40), the expulsion recess (24) in particular being formed as a slant on the backside (47) of the chisel head (40), particularly as a slant having an angle (γ) relative to a vertical to the longitudinal axis (35) of the milling chisel (14) in the range of from 15 ° to 25 °, preferably in the range of from 18 ° to 22 °, and more preferably of 20 °, or as a notch.
8. The tool device (11) according to any one of the preceding claims,
   characterized in that
   the milling chisel (14), on the shaft end (43) opposite the chisel tip (17), has a fastening section (21) with an external thread, and that the fastening device (19) is a nut, particularly a self-locking nut, which is screwed onto the fastening section (21) against the chisel holder (29), a sealing disk (25) being provided in particular, which is braced between the nut and the chisel holder (29) and which seals the shaft receptacle (26) of the chisel holder (29) to the outside.
9. The tool device (11) according to any one of the preceding claims,
   characterized in that
   the milling chisel (14) and the chisel holder (29) are made in such a way that a form locking device is provided between the milling chisel (14) and the chisel holder (29) for securing against rotation, which is designed in such a way that the milling chisel (14) is prevented from rotating about its longitudinal axis (35) in the chisel holder (29).
10. The tool device (11) according to claim 9,
    characterized in that
    the form locking device comprises a recess (45) on the chisel holder (29) and a projection (46) on the milling chisel (14), or vice versa, the recess (45) and the projection (46) being designed complementary to each other in such way that, when the tool device (11) is assembled, they engage each other in the circumferential direction to the longitudinal axis of the milling chisel in a form locking manner and prevent the milling chisel (14) from rotating about its longitudinal axis (35) in the chisel holder (29), the recess (45) in particular being formed on the face side (27) opposite the backside (47) of the chisel head (40) and the projection (46) in particular being formed on the backside (47) of the chisel head (40), in particular integrally with a wear protection cap (18).
11. The tool device (11) according to claim 10,
    characterized in that
    multiple projections (46), or recesses (45), and expulsion recesses (24) are provided, and that the projections (46), or recesses (45), are arranged so as to alternate with the expulsion recesses (24) in the circumferential direction of the chisel shaft (20), the projections (46), or recesses (45), and the expulsion recesses (24) being in particular arranged symmetrically in such a way that the milling chisel (14) can be installed after rotation by 90 °, more preferably by 180 °, without changing the configuration of the projections (46), or recesses (45), and the expulsion recesses (24) in the tool device (11).
12. A milling chisel (14) or a quick-change chisel holder (13) for a tool device (11) according to any one of claims 1 to 11.
13. A ground milling machine (1) with a tool device (11) according to any one of claims 1 to 11.

Images