Abstract
A highly wear-resistant chisel tip body comprising a material that includes diamond particles or monocrystalline diamond structures, in particular a PCD, CVD or NPD material, with a cutting top and a mounting bottom opposite said cutting top, via which the chisel tip body is attachable to a support body. The invention further relates to a milling chisel, a milling drum, as well as a ground milling machine having such a chisel tip body.
Claims
1-17. (canceled)
18. A highly wear-resistant chisel tip body comprising: a material comprising diamond particles or monocrystalline diamond structures, in particular a polycrystalline diamond (PCD), chemical vapor deposition (CVD) or nano-polycrystalline diamond (NPD) material, with a cutting top and a mounting bottom opposite the cutting top, via which the chisel tip body is attachable to a support body, wherein the cutting top includes a cutting tip and two cutting flanks declining from the cutting tip and arranged opposite one another; wherein, in a projection into a plane, the cutting top includes a circumferential outer contour and the cutting tip is arranged, with respect to the outer contour, at an off-center position within the outer contour; and wherein, starting from the chisel tip, a ridge line is provided which extends towards a center of the outer contour and towards the opposite side and along at least one cutting flank and declines towards the mounting bottom such that the chisel tip, the ridge line and the two cutting flanks form a cutting wedge.
19. The chisel tip body according to claim 18, wherein the material has a hardness of more than 40 GPa and a bending rupture strength of more than 2 GPa.
20. The chisel tip body according to claim 18, wherein the chisel tip body is producable by sintering a tip body of a polycrystalline diamond matrix with a base body consisting of a hard metal.
21. The chisel tip body according to claim 18, wherein the ridge line is part of an essentially planar ridge surface.
22. The chisel tip body according to claim 18, comprising at least one of the following features: a subregion shaped as an oblique pyramid; the chisel tip body is surface-symmetrical and not rotation-axially symmetrical; the outer contour is axially symmetrical and not rotationally symmetrical; the outer contour is centrosymmetrical and not rotationally symmetrical; the outer contour corresponds to a planar shape with at least four or more corners; the ridge line and further contour lines on the cutting top of the chisel tip are rounded; and the chisel tip body includes two opposed cutting flank surfaces which extend at an angle ranging from 60° to 150°.
23. The chisel tip body according to claim 18, wherein the chisel tip body comprises two chisel tips spaced from one another by a saddle region, the saddle region being recessed from the two chisel tips towards the attachment side.
24. The chisel tip body according to claim 23, wherein the chisel tip body comprises at least one of the following features: the chisel tip body is axially symmetrical with respect to a symmetry axis through a lowest point of the saddle region; the chisel tip body is not rotationally symmetrical; the chisel tip body includes a symmetry plane extending through both cutting tips; the chisel tip body includes a symmetry plane extending transversely to a virtual connection line between the two cutting tips; and the saddle region comprises two ridge lines which extend within an angular range from <180° to 150° relative to one another.
25. The chisel tip body according to claim 18, wherein the chisel tip body has a length to width ratio larger than 1.2.
26. The chisel tip body according to claim 18, wherein the chisel tip body includes two opposed longitudinal edges extending within an angular range of +/−10°, and parallel to one another.
27. The chisel tip body according to claim 23, wherein the chisel tips and/or the transition in the saddle region are rounded with a rounding radius ranging from 1 mm to 3 mm.
28. The chisel tip body according to claim 18, wherein the chisel tip body is part of a milling chisel for a ground milling machine, the milling chisel having a chisel shank.
29. The chisel tip body according to claim 28, wherein the chisel tip body is arranged resting on an external surface of a circular cone such that a longitudinal axis of the chisel shank and a symmetry plane extending transversely to a virtual connection line between the two cutting tips intersect, in particular at an angle ranging from 30° to 60°.
30. The chisel tip body according to claim 18, wherein the chisel tip body is part of a milling chisel for a ground milling machine, the milling chisel having a support cap having an external surface to which the chisel tip body is attached by brazing.
31. The chisel tip body according to claim 18, wherein the chisel tip body is part of a milling drum for a ground milling machine.
32. The chisel tip body according to claim 31, wherein the chisel tip body has a clearance angle of >1°, up to a maximum of 20°.
33. The chisel tip body according to claim 31, wherein the chisel tip body is attached to a chisel tip support body of the milling drum, wherein an angle of a planar attachment surface via which the chisel tip body is attached to the chisel tip support body, to a tangential force transmission into the ground to be cut in working operation, is in the range from 70° to 110°.
34. The chisel tip body according to claim 18, wherein the chisel tip body is part of a ground milling machine.
Description
BRIEF DESCRPTION OF THE DRAWINGS
[0039] The invention will be explained in more detail below by reference to the embodiment examples indicated in the figures. In the schematic figures:
[0040] FIG. 1: is a side view of a generic ground milling machine;
[0041] FIG. 2: is a side view of a chisel holder system known from the prior art;
[0042] FIG. 3: is a side view of a milling chisel known from the prior art;
[0043] FIG. 4: is a side view of the longitudinal side of a chisel tip body;
[0044] FIG. 5: is a side view of the transverse side of the chisel tip body of FIG. 4;
[0045] FIG. 6: is a top view of the chisel tip body of FIGS. 4 and 5;
[0046] FIG. 7: is an oblique perspective view of a milling chisel having a chisel tip body according to FIGS. 4 to 6;
[0047] FIG. 8: is a side view of the milling chisel of FIG. 7;
[0048] FIG. 9: is another side view of the milling chisel of FIGS. 7 and 8;
[0049] FIG. 10: is a cross-sectional view through a chisel holder having a milling chisel with a chisel tip body in an alternative design;
[0050] FIG. 11: is an oblique perspective view of the chisel of FIG. 10;
[0051] FIG. 12: is a side view of the longitudinal side of the chisel tip body of FIGS. 10 and 11;
[0052] FIG. 13: is a side view of the transverse side of the chisel tip body of FIGS. 10 to 12;
[0053] FIG. 14: is a top view of the chisel tip body of FIGS. 10 to 13;
[0054] FIG. 15: is an oblique perspective view of a preform and a bottom piece for obtaining the chisel tip body of FIGS. 10 to 14;
[0055] FIG. 16: is a perspective view of an enlarged subregion of the ground engagement of the chisel tip body of FIGS. 10 to 14;
[0056] FIG. 17: shows three alternative rotational positions of a chisel having the chisel tip body of FIGS. 10 to 14;
[0057] FIG. 18: is an oblique perspective view of a milling drum equipped with chisels having the chisel tip bodies of FIGS. 10 to 14;
[0058] FIG. 19: is an oblique perspective view of the respective top parts of a prior art milling chisel, a milling chisel according to the first embodiment example and a milling chisel according to the second embodiment example in the cutting direction;
[0059] FIG. 20: is an oblique perspective view of the respective top parts of a prior art milling chisel, a milling chisel according to the first embodiment example and a milling chisel according to the second embodiment example against the cutting direction;
[0060] FIG. 21: is an oblique perspective view of the respective top parts of a prior art milling chisel, a milling chisel according to the first embodiment example and a milling chisel according to the second embodiment example transversely to the cutting direction; and
[0061] FIGS. 22a to 22b: are side views of various ground milling machines.
DETAILED DESCRIPTION
[0062] Like parts or functionally like parts are designated by like reference numerals in the figures. Recurring parts are not designated separately in each figure.
[0063] FIG. 1 illustrates a generic ground milling machine 1, in this case a road milling machine or cold milling machine of the center rotor type, in which the chisels having the chisel tip bodies according to the invention as described in more detail below can be used. It includes an operator platform 2, a machine frame 3, a drive engine 4 and traveling devices 6 (wheels or crawler tracks). In working operation of the ground milling machine 1, the ground 8 to be milled off is removed in the working direction a by a milling drum 9 mounted for rotation about the rotation axis 10 inside the milling drum box 7. The milled material is transported away via the discharge conveyor 5.
[0064] The hollow-cylindrical support tube of the milling drum 9 has a plurality of chisel devices 11 mounted thereon, one of which is indicated in FIG. 2 as an example. The chisel devices 11 each comprise a chisel holder 12 and a milling chisel 13 (=chisel), which is inserted with its shank 14 (FIG. 3; indicated by dashed lines in FIG. 2) into a receiving opening. The tool region P of the chisel 13 protrudes from the chisel holder 12. In working operation of the ground milling machine 1, said chisel region is driven into the ground in the tool's advancing direction b (also in FIG. 9) through rotation of the milling drum 9 about its rotation axis to mill off the ground. In this example, the chisel holder 12 is composed of a quick-change tool holder 16 and a base holder 17, said quick-change tool holder 16 being attached to the base holder 17 and the latter being attached to the milling drum 9.
[0065] A milling chisel 13 as known from the prior art is indicated in more detail in FIG. 3. The milling chisel 13 is subdivided into the tool region P, which contacts the underlying ground in working operation, and a holder region Q, which is located behind the former and is received in the quick-change tool holder. In the mounted state, the holder region Q is thus exclusively fitted into the receiving opening in the holder or quick-change tool holder and is thus covered towards the outside by the chisel holder 12. The milling chisel 13 further includes a chisel tip body 19 soldered onto a base body 20 of the milling chisel 13. Said chisel tip body 19 consists of an ultra high strength material and comprises diamond particles and/or a monocrystalline diamond structure, in particular a PCD or NPD material. This chisel type frequently suffers breakage of the chisel tip body in certain operation situations.
[0066] FIGS. 4 to 6 now first illustrate the structure of a highly wear-resistant chisel tip body 19 according to the invention having a cutting top or working side 22 and an attachment side or mounting bottom 26. The cutting top is that external surface of the chisel tip body 19 which in working operation makes contact with the ground material to be milled, i.e. performs the actual cutting work. This is also where the wear occurs. The mounting bottom 26, which is essentially located opposite the cutting top, on the other hand, is that side of the chisel tip body 19 via which the chisel tip body 19 is connected or linked to a support structure, in particular directly or indirectly to a chisel base body, and thus the forces applied to the chisel tip body 19 during the cutting process are deflected into the support structure.
[0067] The single-piece chisel tip base body 19 has a length L, a width B and a height H, the length L corresponding to the longitudinal extension of the chisel tip body 19 in the plane of the mounting bottom 26, the width B corresponding to the width extension extending transversely to the former in the plane of the mounting bottom 26, and the height H corresponding to the extension orthogonal to that plane. FIGS. 4 to 6 illustrate that the longitudinal extension L is larger than the width extension B and the height extension H.
[0068] On the cutting top 22, the chisel tip body 19 has a cutting tip 23. Said cutting tip thus constitutes the point or region of the cutting top 22 having a maximum distance perpendicular to the projection of the mounting bottom 26 into a virtual reference plane, i.e. in the direction of the height H. Two cutting flanks 34A and 34B, which extend opposite each other in a roof-like, mirror-symmetrical manner at the angle β, decline from the cutting tip 23. Starting from the chisel tip 23, they essentially extend towards the mounting bottom in the height direction H and to the transverse side (FIG. 5) opposite the chisel tip in the longitudinal direction L. The cutting flanks 34A and 34B are designed as planar surfaces having an essentially trapezoidal outer edge towards a ridge line or ridge surface described in more detail below and, in the downward direction, towards a circumferential side wall 15 of the chisel tip body 19. The side wall 15 has a linear progression in the height direction H and extends orthogonally to the longitudinal and width directions L and R, respectively, although shapes having a downward slope, in particular in the outward direction, curved shapes, and/or mixed shapes are also conceivable. The two cutting flanks 34A and 34B lie at the angle β relative to one another, which is preferably larger than 90° and in the present embodiment example is approximately 105°.
[0069] FIG. 6 (top view of the cutting top 22 of the chisel tip body 19) illustrates that, in the projection of the top view into a plane, the chisel tip comprises an outer contour 10 or circumferential edge which in the present embodiment example is essentially shaped as a hexagon. The chisel tip 19 is now arranged at an off-center position relative to the geometrical surface center point M (FIG. 6) of the outer contour 10, specifically offset in the longitudinal direction L towards the one side (in FIG. 6 the lower side), and is in particular located in the region of the first 25%, in particular the first 15%, of the maximum longitudinal extension in the longitudinal direction L with respect to an edge region (in FIG. 6, as an example, the lower edge region of the outer contour 10).
[0070] Starting from the chisel tip 23, a ridge line 33 further extends to the opposite transverse side of the chisel tip body 19, declining towards the mounting side 26. The ridge line 33 here corresponds to the contour line opposite the mounting side 26 in a projection of the chisel tip body 19 into a virtual reference plane spanned by the height H and the longitudinal extension L. In the embodiment example, the ridge line 33 extends, in a straight line and with a uniform slope, from the chisel tip 23 across nearly the entire longitudinal extension L towards the opposite side. Relative to a horizontal line starting from the chisel tip 23, the ridge line 33 thus extends in a line which is inclined by an angle ε of approx. 8°.
[0071] The ridge line 33 further extends within a planar ridge surface 33′, which altogether has an essentially tetragonal base area, as can be seen, for example, from FIG. 6. The ridge surface 33′ with the ridge line and the cutting flanks together form a cutting wedge that starts from the chisel tip and altogether enables excellent cutting properties and at the same time an optimized force transmission, as will be described in more detail below.
[0072] FIGS. 4, 5 and 6 further illustrate that the chisel tip body 19 in the present embodiment example is not rotationally symmetrical but is mirror-symmetrical along the ridge line 33 extending centrally through the ridge surface 33′, as can be seen in particular from FIG. 5.
[0073] In the present embodiment example, the transitions of the ridge surface 33′, the cutting flanks 34A and 34B as well as the side wall 15 are further connected to one another via rounded transition regions 18 (in the figures, the lines indicated in the surface show respective changes in the surface progression). A sharp-edged transition may be provided as well. However, the rounding is easy to manufacture and would occur with increasing wear in a more or less defined manner anyway.
[0074] FIGS. 7, 8 and 9 now show a milling chisel 13 according to the invention in which the chisel tip body 19 described in FIGS. 4 to 6 forms the part that mills the ground in milling operation. FIG. 7 is an oblique perspective view, FIG. 8 is a side view, and FIG. 9 is a side view which is rotated by 90° about the longitudinal axis R compared to FIG. 8 and is slightly inclined towards the viewer with the chisel tip body. Essential elements of the milling chisel 13 besides the chisel tip body are a base body 20 designed rotationally symmetrical about its longitudinal axis with a holder region Q essentially formed by a chisel shank body 27 and a tool region P which in the present embodiment example is formed towards the outer side by a holding cap 21 essentially covering the tip region of the milling chisel 13. The chisel shank body 27 essentially comprises a steel support body which forms the conical portion 28 and the cylindrical portion 29 in the holder region Q adjoining the holding cap 21, in particular in an integral and material-uniform manner The cylindrical portion 29 may, for example, additionally include a male or female thread for the purpose of attachment inside a chisel holder, in particular at an end position. The holding cap 21 preferably likewise consists of a hard metal or at least of a material that has a higher resistibility against wear compared to conventional steel.
[0075] The chisel tip body 19 is laterally attached to the essentially circular-conical holding cap 21, in particular via a suitable soldered connection, in particular a brazed connection. Starting from the point of maximum projection formed by the cutting tip 23, the chisel tip body thus extends in the direction of the longitudinal axis of the chisel shank towards the holder region Q, and thus in the present case laterally along the external jacket surface of the holding cap 21. For this, provision may in particular be made for a specifically dedicated flattening and/or groove with a planar contact surface at the holding cap 21 for fixing the chisel tip body 19 with its mounting bottom 26 to the external side of the holder cap 21, in particular via a brazed connection. What is essential here is that the tip, i.e. the point of maximum projection in the direction of the rotation axis or longitudinal axis R of the milling chisel 13, is formed by the cutting tip 23 of the chisel tip base body 19 and not by the holder cap 21. This ensures that the actual cutting work is primarily performed by the chisel tip body 19 of the milling chisel 13.
[0076] FIGS. 10 to 16 show a second embodiment example of the invention. FIG. 10, to begin with, is a cross-sectional view through a base holder 17, which may, for example, be welded onto the external jacket surface of a milling drum tube and has an inserted quick-change chisel holder 16 which in turn holds the milling chisel 13. A holding part, via which the chisel shank body 27 is connected to the holding cap 21, is first adjoined by a conical portion 28 tapering, in a direction away from the holding cap 21, perpendicular to the axis P, which finally merges into an attachment portion 29. The latter comprises a female thread 30 for receiving a fastening screw 31 for clamping the milling chisel 13 inside the chisel holder 12 in a manner known per se in the prior art. The difference between the milling chisel 13 shown here and the first embodiment example consists in the specific geometrical design of the chisel tip body 19, as will be explained in more detail below.
[0077] In contrast to the first embodiment example, the chisel tip body 19 comprises, on its working side or cutting top 22, two cutting tips 23a and 23b spaced from one another, which are spaced from one another by the distance 25 via a saddle region 24. In this case as well, the single-piece chisel tip body 19 comprises an ultra high strength material, preferably a PCD or NPD material. Again, an attachment side 26 is provided opposite the cutting top 22, via which the chisel tip body 19 is attached to an essentially circular-conical holding cap 21, in particular via a soldered connection. On the side opposite the chisel tip body 19, the circumferential, material-uniform and integral holding cap 21 is connected to a chisel shank body 27, which in actual working operation essentially functions to carry the milling chisel 13 in a chisel holder 12. It may consist, for example, of a steel material.
[0078] Further details regarding the design of the chisel shank body 27, which is essentially rotationally symmetrical about the axis P, can also be taken in particular from FIG. 11, which shows the milling chisel 13 of FIG. 10 in an oblique perspective view. A holding part, via which the chisel shank body 27 is connected to the holding cap 21, is first adjoined by a conical portion 28 tapering, in a direction away from the holding cap 21, perpendicular to the axis P, which finally merges into an attachment portion 29. The latter comprises a female thread 30 for receiving a fastening screw 31 for clamping the milling chisel 13 inside the chisel holder 12 in a manner known per se in the prior art. The difference between the milling chisel 13 shown here and the first embodiment example consists in the specific geometrical design of the chisel tip body 19, as will be explained in more detail below. As regards further features of the second embodiment example, reference is further made to the corresponding discussions of the first embodiment example, and vice versa.
[0079] FIGS. 10 and 11 thus illustrate that also the chisel tip body 19 of this embodiment example is, in contrast to the prior art, not set atop the tip of the holding cap 21 but is instead essentially attached laterally in the tip region of the holding cap 21 (wherein recesses may in particular be provided in the holding cap 21 to enable planar attachment of the chisel tip body 19 via the soldered connection) while at the same time forming the tip of the milling chisel 13.
[0080] FIGS. 12, 13 and 14 further illustrate the specific geometrical design of the chisel tip bodies 19. FIG. 12 is a longitudinal view, FIG. 13 is a transverse view orthogonal thereto, and FIG. 14 is the top view showing the chisel tip body 19 from above orthogonally to the former two views. The chisel tip body 19 has a length L (FIG. 12), a width B (FIG. 13) and a height H (FIG. 14). The length L is larger than the width B at least by a factor 1.4.
[0081] What is of particular importance here is that, in contrast to the first embodiment example, the chisel tip body 19 includes two tips, more specifically the two cutting tips 23a and 23b. The two cutting tips 23a and 23b are spaced from one another by the distance S1 via the saddle region 24. The saddle region 24 includes, with respect to its ridge line, a saddle point W1 located halfway along the distance S1. At this lowest point of the ridge line of the saddle region 24, the ridge line is recessed towards the attachment side 26 by the distance S2. The two cutting tips 23a and 23b are rounded and have a curvature radius R1 in the longitudinal view according to FIG. 12 and a curvature radius R2 in the transverse view according to FIG. 13. Respective ridge lines 33a and 33b, which are essentially linear, extend between the saddle point W1 and the cutting tips 23a and 23b. The ridge lines 33a and 33b intersect at the saddle point W1 and together form a continuous linear ridge line. In the present embodiment example, they confine an angle α of approx. 170° (FIG. 12).
[0082] Along the longitudinal sides, the chisel tip body 19 comprises two continuous and nearly planar cutting flanks 34A and 34B. These lie at an angle β of approx. 100° relative to one another.
[0083] FIGS. 12, 13 and 14 illustrate in particular that the chisel tip body 19 is not rotationally symmetrical but in the present case includes two mirror symmetry planes E1 (FIG. 12; the plane extending through the chisel tip body 19 transversely to the connection line between the cutting tips 23a and 23b) and E2 (FIG. 13; the plane extending through the chisel tip body 19 and including the two cutting tips 23a and 23b).
[0084] FIG. 15 illustrates an approach for obtaining the chisel tip body 19 in the manufacturing process. According to the manufacturing process, the chisel tip body 19, which was integral in the previous figures, is subdivided into a cutting piece 35 and a bottom piece 36. This subdivision may be due to the manufacturing process. The cutting piece 35 here may in particular consist in essential parts of an ultra high strength material, in particular a PCD or NPD material, and may be manufactured separately in a first fabrication process. Further, a bottom piece 36 is provided which does not contain any PCD or NPD material and consists, for example, of a hard metal such as in particular tungsten carbide. In the present embodiment example, the single-piece chisel tip body 19 is obtained by sintering the cutting piece 35 onto the bottom piece 36, wherein a nubbed external surface may be provided on the contact surface of the bottom piece 36 towards the cutting piece 36 to improve this sintering process. However, alternative manufacturing techniques may also applied within the scope of the invention to obtain the chisel tip body 19. At the bottom piece 36, the chisel tip body 19 has an essentially constant width B and length L, which respectively correspond to the maximum width B and the maximum length L of the cutting piece 35. The cutting piece 35, on the other hand, is designed so as to taper, in particular in its width B, away from the bottom piece 36 and up to the ridge line between the two cutting tips 23a and 23b and the saddle point. In contrast to this, the length of the chisel tip body 19 is essentially constant across the cutting piece 35 and the bottom piece 36 up to the roundings of the cutting tips 23a and 23b.
[0085] FIG. 16 shows a cutout view of a chisel tip body 19 engaging the ground when the chisel tip body 19 is mounted in a manner according to the invention, for example, on a milling drum, as shown in more detail inter alia in FIG. 18. The ground 38 is removed by the chisel tip body 19 through cutting. In this case, the chisel tip body 19 is ideally mounted on the milling drum such that it produces a clearance angle γ (angle between the ground processed by the chisel tip body 19 and its side facing the ground (ridge line of the longitudinal side towards the cutting tip 23a)) of more than 1° (in the present embodiment example approx. 10°), but preferably not more than 15°.
[0086] FIG. 16 further illustrates that the force deflection of the force exerted on the chisel tip body 19 by the underlying ground in the milling process (force arrow K in FIG. 16) is mainly effected via the essentially planar soldering surface 39 between the chisel tip body 19 and the holding cap 21, which in the present embodiment example extends at an angle of approx. 86° and thus essentially orthogonally to this force transmission direction. This counteracts breakage of the chisel tip body 19 particularly effectively since in this manner shear loads acting on the connection point between the chisel tip body 19 and the holding cap 21 are particularly low.
[0087] FIG. 16 further shows side walls 40 located opposite each other (only one side is visible in FIG. 16), which extend at an angle, in particular essentially orthogonally, to the soldering surface 39 and also overlap the chisel tip body at the side walls. These side walls 40 facilitate, on the one hand, the mounting of the chisel tip body to the holding cap 21 since the chisel tip body can then be positioned on the holding cap in only two defined positions (which in the case of the twin tip thus involves the same spatial alignment of the chisel tip body with the holding cap), and, on the other hand, they improve attachment of the chisel tip body to the holding cap due to solder entering also between the side walls 40 and the longitudinal side wall of the chisel tip body during the soldering process.
[0088] FIG. 17 shows three chisel devices 11 with inserted milling chisel 13 according to the second embodiment example in various rotational positions in a top view, i.e. essentially against the cutting direction. Line L1 represents the progression of the connection line between the two cutting tips 23a and 23b. Line L2, on the other hand, represents the orientation of the cutting tip 23a, which is positioned externally in the radial direction relative to the rotation axis of the milling drum, perpendicular to the rotation axis. The externally positioned cutting tip 23a provides the cutting circle of the milling chisel 13 in the underlying ground during working operation. In the view shown on the left-hand side, the lines L1 and L2 are congruent. In the view in the middle, the milling chisel 13 is twisted counter-clockwise by the angle μ, and in the view on the right-hand side, it is twisted clockwise by the angle μ. The alternative views of FIG. 17 now illustrate that even though the chisel tip body 19 is not arranged centrally with respect to the longitudinal axis P of the milling chisel, the cutting circle produced by the milling chisel 13 remains the same even for different rotational positions of the milling chisel. This also enables the creation of uniform milling patterns with the present milling chisel 13, and an exact positioning of the milling chisel is not required. Irrespective of this, devices may obviously be provided which serve for twist locking and/or specifying a particular position of the milling chisel 13.
[0089] An arrangement of a plurality of chisel tip bodies 19 on a milling drum is illustrated in FIG. 18. What is essential here is that, with the exception of chisels arranged at the end faces, the individual milling chisels 13 in the present embodiment example all have the same structure and are arranged in chisel holders 12 in a rotationally fixed manner
[0090] FIGS. 19, 20 and 21 illustrate a comparison of a conventional chisel 13′ (left-hand side), a milling chisel 13 according to the invention according to the second embodiment example (middle) and a milling chisel 13 according to the invention according to the first embodiment example (right-hand side) in a view in the approximate advancing direction V in milling operation (FIG. 19), against the approximate advancing direction V (FIG. 20) in milling operation and in a side view.
[0091] FIG. 19, to begin with, illustrates that, with respect to the tip region of the respective milling chisel, the two embodiments according to the invention (middle and right-hand side) as well as the prior art chisel form the actual tip of the milling chisel 13 through their respective chisel tip body. The cutting engagement thus occurs via the chisel tip of the chisel tip body in all cases. However, a significant advantage of the present assembly according to the invention is achieved through the specific elongate design of the chisel tip body and the mounting on the base body of the milling chisel in a laterally declining manner The chisel tip body and its attachment surface on the holding cap thus extend along the holding cap away from the tip of the milling chisel at the level of the holding cap in the direction of the longitudinal axis of the milling chisel. In the prior art according to the left picture, the chisel tip body is set atop the remaining milling chisel 13′, for example a holding cap, and does not extend along the holding cap of the milling chisel. In the milling process, the force is thus transmitted (force arrow K) to its attachment surface 39 in an acute angle α, whereas in the design according to the invention the force is transmitted at least in an obtuse angle α (preferably more than 70° and in particular more than 80° and thus nearly orthogonally. As a result, shear forces at the connection point of the chisel tip body 19 towards the holding cap 21, which might cause the chisel tip body 19 to be torn off, are reduced drastically and the milling chisel thus overall has a considerably higher loadability.
[0092] FIGS. 22a and 22b finally show specific examples of further ground milling machines which gain particular advantage from being equipped with milling chisels according to the invention. FIG. 22 shows a stabilizer/recycler in a design known per se. FIG. 22b shows a highly schematic view of a milling device as used, for example, in a trench miller or as an attachable unit. A surface miner may, for example, have the structure of the machine shown in FIG. 1.
