EP3467255B1 - Pick holder - Google Patents

Description

The invention relates to a chisel holder for a soil cultivation machine, in particular a road milling machine, with a support body on which a holding section is formed in the area of a processing side, into which a chisel holder for receiving the shaft of a round-shaft chisel is formed, the holding section being on its side facing away from the support body End of a wear surface enclosing the chisel receptacle for the contact of the round-shaft chisel or a support element is closed, the chisel receptacle being transferred indirectly or directly into the wear surface via a centering surface of a centering receptacle that is aligned obliquely to the central longitudinal axis of the chisel receptacle and whereby a plug-in attachment is provided on the side opposite the holding section Attachment of the chisel holder to a base holder is formed on the support body.

Soil cultivation machines are used to carry out milling work on hard surfaces, such as roads. These each have a rotating milling drum. A large number of chisels are attached to the milling drum, which penetrate into the subsoil through the rotation of the milling drum and remove it. The chisels are subject to high levels of wear. It is therefore known to attach the chisels interchangeably to a milling drum tube of the milling drum. For this purpose, base holders can be firmly attached to the milling drum tube, for example by welding. A chisel holder can then be releasably attached to such a base holder. The chisel holder has a chisel holder in which a chisel can also be releasably mounted. Worn chisels can be easily replaced. If the chisel holder is worn out after several chisel changes, it can be removed from the base holder and replaced. It is known to store the chisels in the chisel holder so that they can rotate about their longitudinal axis and are axially blocked. During the milling process, the chisels rotate about their longitudinal axes, which means that a chisel tip or a chisel head that engages in the subsurface is positioned evenly over theirs Circumference is worn. In order to absorb axially acting forces, the chisel head rests directly on the chisel holder or with the interposition of a support element. Due to the rotation, the chisel holder is subject to increased wear in the area where the chisel head or the support element rests. In addition to the axial forces, strong transverse forces also act on the chisel during soil cultivation. These lead to uneven wear of the chisel holder in the area of the support of the chisel head or the support element. Furthermore, they lead to high forces in the transition from the bit holder to the base holder. If the chisel holder wears unevenly, the free rotation of the chisel will be restricted. In particular, this then tends to block. However, if the rotation of the chisel is restricted, it will no longer wear evenly along its circumference in the desired manner. Rather, one-sided wear occurs, which leads to premature tool failure.

From the DE 10 2014 104 040 A1 is a chisel, especially a round-shaft chisel, known with a chisel head and a chisel shaft. The chisel is held with its chisel shaft in a cylindrical chisel holder of a holding attachment of a chisel holder. For this purpose, the chisel shaft is secured in the chisel holder by means of a fastening sleeve, which can be rotated about its central longitudinal axis but is axially blocked. The chisel head, which is larger in diameter than the chisel shaft, rests on a wear surface of the holding attachment via a disk-shaped support element on the front side and all around the chisel holder. The holding attachment is cylindrical. Opposite the chisel, the holding attachment is connected to a base part of the chisel holder. The base part extends transversely to the holding attachment. Laterally offset and opposite to the holding attachment, a plug-in attachment is formed on the base part. This is used to attach the chisel holder to a base holder of a milling drum described above. The chisel holder is designed as a through hole. It penetrates the retaining attachment.

Towards the chisel, the chisel holder widens into a centering holder. The surface of the centering mount is oblique to the central longitudinal axis Chisel holder aligned. It merges into the wear surface of the holding attachment via a bead. The bead protrudes beyond the wear surface. The surface of the support element facing the holding attachment is designed to be complementary to the end face of the holding attachment. The support element rests with a seat on the wear surface of the holding attachment. In the area of the bead, a circumferential groove is formed in the support element, which receives the bead. A centering projection of the support element that protrudes beyond the seat engages in a form-fitting manner in the centering receptacle of the chisel holder. Through the engagement of the centering projection in the centering receptacle and the bead in the groove, the support element is guided in the radial direction.

In order to ensure that the chisel can be rotated about its central longitudinal axis, axial play of the chisel in the chisel holder is required. A larger axial play is provided for larger chisels than for smaller chisels. If the axial play exceeds the height of the centering receptacle, the lateral guidance of the support element is lost through the centering attachment. This leads to increased and uneven wear on the bit holder, which reduces its service life. This applies in particular to the high transverse forces that are transmitted from the chisel head via the support element to the wear surface of the holding attachment and lead to uneven abrasion if the support element is not precisely guided. At the same time, the high transverse forces lead to a heavy load on the plug-in attachment and the fastening elements with which the plug-in attachment is held in the base holder. These can lead to fatigue fractures on the plug-in attachment or to wear or loosening of the fastening elements and thus to damage or loss of the chisel holder with the chisel attached to it.

From the EP 1 427 913 B1 an assembly with a rotatable cutting bit and a disc is known. The disk has ribs on its front side facing the head of the cutting bit and recesses on its opposite back, which improves the rotatability of the disk about its central axis. On its back is circumferential and adjacent a central hole is formed with a centering attachment with a surface aligned obliquely to the central axis. When the chisel is mounted, the centering attachment engages in a chamfer attached to the end of a cylindrical chisel holder of a chisel holder. This causes the disc to be guided laterally. The bevel protrudes only slightly beyond the back of the pane. Due to the required axial play of the cutting bit, the centering attachment can be disengaged from the chamfer, so that its lateral guidance is lost. This leads to increased wear on both the disc and the bit holder, particularly when there are high transverse forces acting on the bit.

It is the object of the invention to provide a chisel holder for a soil cultivation machine, in particular a road milling machine, which has a long service life.

The object of the invention is achieved in that a centering height measured in the direction of the central longitudinal axis, which is between an end of the centering receptacle facing away from the wear surface and a maximum point of an extension projecting beyond the wear surface, is designed in such a way that the ratio between the inner diameter of the chisel receptacle and the Centering height is less than 8, and that the support body has one or more removal surfaces on its side facing away from the holding section, the one removal surface extending on both sides of a central plane which receives the central axis and which extends in the direction of the feed direction, or that on both sides of this Central plane extends at least one removal surface

The centering receptacle serves to accommodate and guide a centering approach of a support element, as can be arranged between a round-shank chisel and the holding section of the bit holder, or a centering approach which is molded directly onto the round-shaft chisel when it rests against the holding section without an intermediate support element. The centering attachment is designed to be complementary in shape to the centering receptacle and stands over a surface (seat surface or support surface) facing the chisel holder Support element or the chisel head. The centering approach is therefore in engagement with the centering receptacle. As a result, the support element or the round shank chisel is guided radially. If a shoulder is formed in the area of the wear surface of the chisel holder, it engages in a corresponding recess in the seat surface of the support element or in the support surface of the chisel head. This achieves additional lateral guidance of the support element or the chisel head. The measure that the ratio between the inner diameter D _i of the chisel holder and the centering height is less than 8 ensures sufficient blocking or reduction of lateral movement of the support element or the round shank chisel relative to the chisel holder. The centering height can be chosen to be greater than the maximum axial play of the round shank bit expected over the life expectancy of the pick. The axial play is greater for large round-shank chisels with correspondingly large chisel shanks than for comparatively small round-shank chisels. This is taken into account by specifying the ratio between the inside diameter D _i of the chisel holder and the centering height. Good lateral guidance of the support element or the round shank chisel is therefore guaranteed for all chisel sizes used when the chisel is pulled out of the chisel holder to the maximum within the axial play. Due to the slight lateral movement of the support element and the round shank chisel, the longitudinal wear of the holding section of the chisel holder can be kept low. This applies in particular to high transverse forces acting on the round shank chisel, which are transmitted via the support element or directly from the chisel head to the wear surface of the chisel holder. If the lateral guidance of the support element or the round shank bit is inadequate, such uneven loads on the wear surface lead to asymmetrical and therefore increased wear. Due to the inventive design of the centering receptacle and, if applicable, the attachment depending on the diameter of the chisel holder, the wear of the chisel holder is significantly reduced, especially when high transverse forces occur. As a result, the chisel holder needs to be replaced much less frequently.

As already shown above, high transverse forces also lead to a heavy load on the plug-in extension and the fastening elements with which the plug-in extension of the chisel holder is held in the base holder. In order to adapt the service life of the attachment of the bit holder to the extended service life of the holding section, it is provided according to the invention that the support body has on its side facing away from the holding section at least two removal surfaces (first or second removal surfaces) which form a pair of removal surfaces and which are at an angle to one another. When the chisel holder is installed, these removal surfaces rest on corresponding support surfaces of the base holder, to which the chisel holder is attached with its plug-in attachment. Forces transmitted to the round shank chisel and thus the chisel holder are transferred to the base holder both via the plug-in attachment and via the removal surfaces. This relieves the load on the plug-in attachment and its fastening elements, which means that premature wear or breakage of the plug-in attachment and the fastening elements can be avoided. Due to the removal surfaces that are at an angle to one another, high transverse forces in particular can be transferred to the base holder. The removal surfaces are preferably aligned in such a way that the forces to be transmitted from the removal surfaces to the support surfaces are essentially aligned in the direction of the surface normal of one of the removal surfaces or the support surfaces. Due to the removal surfaces that are at an angle to one another and form a pair of removal surfaces, the support body and thus the bit holder can preferably be designed symmetrically. The chisel holder can thus be used in all positions of the milling drum, which are aligned in mirror image to one another, for example on the opposite sides of the milling drum.

The centering receptacle, in conjunction with the centering attachment, also leads to a labyrinth-like seal. This reduces wear on the chisel. The sealing effect can be further improved by lugs arranged on the wear surface, which engage in corresponding recesses.

According to a preferred embodiment variant of the invention, it can be provided that the ratio between the inner diameter D _i of the chisel holder and the centering height is less than 7.5, preferably less than 7.0, particularly preferably less than 6.5. With a ratio of less than 7.5, good lateral guidance is achieved even with transverse forces acting directly on the support element or the round shank bit, for example from impacting overburden material. A ratio of less than 7.0 further improves the lateral guidance, so that the simultaneous action of axially aligned forces distributed unevenly over the support element and radially acting transverse forces does not lead to a wobbling movement of the support element, resulting in high levels of wear. With a ratio of less than 6.5, sufficient lateral guidance is achieved even towards the end of the service life of the support element and the round shank bit, when the wear that has already occurred may cause the axial play of the round shank bit to be excessively increased.

A radially acting guidance of the support element and/or the round-shaft chisel while at the same time providing good rotatability of the support element and/or the chisel can be achieved in that the extension is arranged circumferentially to the chisel holder.

The lateral guidance of the support element can be further improved in that several approaches of the same or different heights are formed on the wear surface of the holding section and that the ratio between the inside diameter D _i of the chisel holder and the centering height to one of the approaches, preferably the ratio between the inside diameter D _i of the chisel holder and the largest centering height determined for an approach is less than 8.

By means of several lugs arranged radially next to one another, which engage in corresponding recesses, the projected surface of the wear surface is maintained in the axial direction, the contact surface between the However, the chisel holder and the support element or the round shank chisel in the radial direction are enlarged. This allows larger transverse forces to be absorbed. At the same time, the contact area between the bit holder and the support element or the round shank bit is increased, which has a positive effect on wear behavior. The adjacent approaches and the recesses that accommodate the approaches further significantly improve the sealing effect against penetrating overburden material. Due to the ratio of less than 8 between the inner diameter D _i of the chisel holder of the chisel holder and the centering height, sufficient radial guidance of the support element and the round shank chisel is achieved even when the support element or round shank chisel is lifted maximally from the wear surface within the scope of the axial play.

A further improvement in the lateral guidance can be achieved in that a guide groove is formed into the adjacent wear surface at a distance and circumferentially from the centering receptacle. The guide groove enables a guide bar formed on the support element or the round shank chisel to engage in this. This improves the rotatability of the support element or the round shank chisel, which leads to reduced longitudinal wear of the holding section of the chisel holder.

Good rotatability of the support element or the round shank chisel can be achieved by forming the extension between the centering receptacle and the guide groove and by ensuring that the centering receptacle has a greater depth than the guide groove relative to the adjacent wear surface. In this way, triple radial guidance of the support element or the round shank bit on the bit holder is achieved, namely in the area of the centering receptacle, on the shoulder and on the guide groove.

The rotatability of the support element or the round shank chisel can be further improved by ensuring that transitions between the centering surface, the wear surface, the shoulder and/or the guide groove are continuous or rounded. This avoids sharp edges that block rotation
Good lateral guidance of the support element or the round shank chisel can result from the height of the attachment relative to the wear surface being greater than or equal to 0.3 mm, preferably between 0.3 mm and 2 mm, particularly preferably between 0.5 mm and 1 .5 mm. With an approach smaller than 0.3 mm, it is not possible to achieve a sufficient improvement in the lateral guidance of the support element or the round shank chisel. With an approach in the range between 0.3 mm and 2 mm, good lateral guidance of the support element or round shank chisel can be achieved. In particular, approaches with a height between 0.5 mm and 1.5 mm lead to good rotation of the support element or the round shank chisel.

For common chisel sizes and associated chisel holders, it can be provided that the inside diameter is D; is 20 mm and the centering height is greater than 2.5 mm or that the inner diameter D _i is 22 mm and the centering height is greater than 2.75 mm or that the inner diameter D; 25 mm and the centering height is greater than 3.125 mm or that the inner diameter D; 42 mm and the centering height is greater than 5.25 mm. For smaller chisels, for example for fine milling, chisel holders with an inner diameter D _i of 20 mm or 22 mm and a centering height of at least 2.5 mm or 2.75 mm are suitable. For medium-sized chisels, chisel holders with an inner diameter D; of 25 mm and a centering height of 3.125 mm. For large chisels and associated chisel holders, chisel holders with an inner diameter D _i of 42 mm and a centering height of at least 5.25 mm can be used. With a ratio of less than 8 between the inner diameters D _i of the chisel holders and the respective centering height, suitable centering approaches are provided for all common sizes of the support elements or the round shank chisels. This ensures that, for example, with larger chisels with correspondingly greater forces occurring and a greater axial play of the chisel, there is sufficient lateral guidance of the support elements or the chisel.

Suitable lugs or guide grooves can be provided by attaching the lug and/or the guide groove to the wear surface using a machining manufacturing process during the production of the bit holder. If the attachment and/or the guide groove are already attached to the wear surface during the production of the chisel holder, the chisel shaft and the chisel holder are protected from contamination by the formed, labyrinth-like seal at the start of operation. The good lateral guidance is already present when the chisel holder is new, so there is little wear right from the start.

The transfer of transverse forces acting on the chisel via the chisel holder to the base holder can be improved in that the support body has at least one further removal surface which is at an angle to the two removal surfaces of the removal surface pair. The at least three, particularly preferably four, removal surfaces are preferably aligned in such a way that at least one of the surface normals of the removal surfaces runs at least approximately in the direction of the force action given the possible transverse forces that occur. The force can thus preferably be transferred from the removal surfaces aligned transversely to it to the base holder. This significantly reduces the load on the plug-in attachment of the chisel holder.

Figur 1

in einer perspektivischen Seitenansicht einen lösbar mit einer Basishalterung verbundenen Meißelhalter,

Figur 2

die in Figur 1 gezeigte Basishalterung mit dem Meißelhalter in einer Explosionsdarstellung,

Figur 3

den in den Figuren 1 und 2 gezeigten Meißelhalter in einer Frontansicht,

Figur 4

den in den Figuren 1, 2 und 3 gezeigten Meißelhalter in einer Rückansicht,

Figur 5

einen Ausschnitt eines Werkzeugsystems mit jeweils einem Ausschnitt von einem Halteabschnitt des Meißelhalters, einem Stützelement und einem in dem Meißelhalter gehaltenen Rundschaftmeißel,

Figur 6

in einer schematischen Darstellung den Verschleiß einer Verschleißfläche eines bekannten Meißelhalters,

Figuren 7, 9-14

in schematischen seitlichen Schnittdarstellungen jeweils einen Ausschnitt eines Halteabschnitts im Bereich einer Zentrieraufnahme, und

Figuren 8, 15

einen Halteabschnitt, bei dem nicht erfindungsgemäß kein Ansatz vorgesehen ist, der über die Verschleißfläche hinausragt.

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

Figure 1

in a perspective side view a chisel holder detachably connected to a base holder,

Figure 2

in the Figure 1 shown base holder with the chisel holder in an exploded view,

Figure 3

the one in the Figures 1 and 2 Chisel holder shown in a front view,

Figure 4

the one in the Figures 1 , 2 and 3 Chisel holder shown in a rear view,

Figure 5

a section of a tool system, each with a section of a holding section of the bit holder, a support element and a round shank bit held in the bit holder,

Figure 6

in a schematic representation the wear of a wear surface of a known chisel holder,

Figures 7, 9-14

in schematic side sectional views, a section of a holding section in the area of a centering receptacle, and

Figures 8, 15

a holding section in which, according to the invention, no approach is provided which protrudes beyond the wear surface.

Figure 1 shows a perspective side view of a chisel holder 20 that is detachably connected to a base holder 10. Opposite the chisel holder 20, the base holder 10 is closed off by a concavely shaped, lower end side 11. With this end page 11, the base holder 10 can be attached to a milling drum tube, not shown, of a soil cultivation machine, in this case a road milling machine. In order to be able to transmit high forces, the base holder 10 is preferably welded to the milling drum tube. A base body 13 of the base holder 10 has two inclined surfaces 15 arranged at an angle and, based on a central longitudinal plane of the base holder 10, symmetrically to one another at the front in the working direction. This is adjoined at an angle by two inclined surfaces 14 arranged in mirror image to the central longitudinal plane of the bass holder 10, only one of which can be seen in the present perspective. The inclined surfaces 14 merge into side surfaces of the base body 13 at an angle. The side surfaces are preferably aligned parallel to the working direction of the base holder 10 when operating on a milling drum. Due to the arrangement of the inclined surfaces 15, the inclined surfaces 14 and the adjoining side surfaces, overburden material slides past the base holder 10 to the side.

The chisel holder 20 has a support body 21, which is closed off at the front by an apron 22. A holding section 30 is molded onto the support body 21 facing away from the base holder 10. The holding section 30 is cylindrical. Opposite the support body 21, the holding section 30 is closed off by a wear surface 31. The wear surface 31 is arranged all around a chisel holder 32 of the chisel holder 20. The chisel holder 32 is formed by a cylindrical bore. She is along one in the Figures 6-15 shown central longitudinal axis M aligned. The chisel holder 32 widens in a chamfer shape at its end facing the wear surface 31 in the area of a centering holder 33. Circumferential to the centering receptacle 33, a bead-shaped extension 34 is formed on the wear surface 31 and projects beyond it parallel to the central longitudinal axis M. Wear markings 30.1 are provided on the outer surface of the holding section 30. In the present case, the wear markings 30.1 are designed as circumferential grooves. They are arranged at different distances from the wear surface 31. Lengthwise wear of the holding section 30 can be recognized and evaluated using the wear markings 30.1. The chisel holder 20 is symmetrical to one in the Figures 3 and 4 shown central transverse plane MQ, this central transverse plane MQ accommodates the central longitudinal axis M of the chisel holder 32 and extends in the direction of the feed direction V, like that Figures 3 and 4 reveal. The surface of the support body 21 and the apron 22 facing away from the base holder 10 form drainage surfaces for the overburden material. These are aligned obliquely to the central transverse plane MQ, so that a web 26 aligned in the direction of the central transverse plane MQ is formed in front of the holding section 30 in the working direction.

Figure 2 shows the in Figure 1 shown base holder 10 with the chisel holder 20 in an exploded view. On the side of the support body 21 opposite the holding section 30 of the chisel holder 20, a plug-in projection 40 is formed onto the support body 21. The plug-in extension 40 is connected to the support body 21 offset from the holding section 30 in the working direction V of the chisel holder 20. It is aligned in the direction of its longitudinal extent towards the base holder 10. Preferably, two contact surfaces 41, of which only one can be seen in the selected perspective, protrude above the surface of the plug-in attachment 40 in the working direction. Contrary to the working direction, within the scope of the invention, a pressure screw receptacle 42 can be formed into the plug-in attachment in the form of a recess. The pressure screw receptacle 42 is preferably closed in the direction of the base holder 10 by a pressure surface 42.1 which extends obliquely to the longitudinal extent of the plug-in extension 40.

The base holder 10 is penetrated by a plug-in receptacle 16.7. The plug-in receptacle 16.7 is aligned in the direction of the plug-in extension 40 of the chisel holder 20. It serves to accommodate the plug-in attachment 40. A threaded receptacle 18 is formed into the base holder 10 at an angle to the plug-in receptacle 16.7. It ends at the end in the plug-in receptacle 16.7. A pressure screw 50 is assigned to the thread receptacle 18. The pressure screw 50 has a threaded section 51, a tool holder 53 and a pressure shoulder 52 opposite the tool holder 53. It can be screwed into the threaded receptacle 18 of the base holder 10 in such a way that the pressure projection 52 protrudes into the plug-in receptacle 16.7.

Aligned laterally and forward in the working direction, the plug-in receptacle 16.7 merges into the first support surfaces 16.1. These are sloping towards the plug-in receptacle 16.7 and aligned symmetrically to a central plane of the base holder 10.

A surface 17 is formed all around the thread receptacle 18. This is laterally delimited by projections projecting beyond the surface 17. Towards the plug-in receptacle 16.7, the projections form second support surfaces 16.2. This are aligned at an angle to each other and sloping towards the plug-in receptacle 16.7 and the central plane of the base holder 10. They are still arranged at an angle to the first support surfaces 16.1. The first and second support surfaces 16.1, 16.2 thus each form prism-shaped contact surfaces for the support body 21 of the chisel holder 20. The first and second support surfaces 16.1, 16.2 are aligned at an angle to one another and slope downward in the direction of the plug receptacle 16.2. Along the angular transitions between the support surfaces 16.1, 16.2, adjustment spaces 16.3, 16.4, 16.5 are formed in the form of depressions. The adjustment space 16.5 formed between the second support surfaces 16.2 merges into the surface 17 delimiting the thread receptacle 18 via a recess 16.6.

The plug-in receptacle 16.7 and the adjacent support surfaces 16.1, 16.2 form a chisel holder receptacle 16.

Figure 3 shows the one in the Figures 1 and 2 Chisel holder 20 shown in a front view and Figure 4 in a rear view. The feed direction V and thus the working direction of the chisel holder 20 are in the Figures 3 and 4 marked by the usual arrow representation. The central transverse plane MQ running in the feed direction V forms a plane of symmetry of the bit holder 20. As in Figure 3 shown, the apron 22 of the support body 21 pointing in the feed direction V forms two first removal surfaces 23 aligned at an angle to one another on its side facing the plug-in projection 40. The first removal surfaces 23 are preferably arranged mirror-symmetrically to the central transverse plane MQ. An asymmetrical arrangement is also conceivable. The removal surfaces 23 are aligned obliquely to the central transverse plane MQ. The first removal surfaces 23 form a first removal surface pair. A transition section 23.1 can be provided between the first removal surfaces 23. The first removal surfaces 23 preferably merge into the plug-in attachment 40 via a rounding transition 23.2. The plug-in extension 40 has the two contact surfaces 41 arranged in mirror images of the central transverse plane MQ in the feed direction V. These can be separated from each other by a recess 43.

As in Figure 4 shown, the support body 21 forms second removal surfaces 24 on its rear section relative to the feed direction V on its surface facing the plug-in projection 40. The second removal surfaces 24 are angled and, based on the central transverse plane MQ, preferably aligned in mirror image to one another. Of course, the second removal surfaces 24 can also be on both sides of the central transverse plane MQ, although they do not have to be mirror images of one another. You can transition into the plug-in attachment 40 via a rounded transition 24.2 or with a sharp edge. An indirect transition is also conceivable. The second removal surfaces 24 form a second removal surface pair. They can be separated from one another, for example, by a throat-shaped transition section 24.1. The transition section 24.1 can preferably run along the central transverse plane MQ of the bit holder 20. The chisel holder 32, designed as a through hole, opens into the transition section 24.1. A throat-shaped flushing channel 25 is guided to the chisel holder 32 in the opposite direction to the feed direction V. The flushing channel 25 forms a radially aligned opening in the chisel holder 32. Through this, waste material introduced into the chisel holder 32 during a milling process can be removed to the outside.

For the purposes of the present invention, for example, the first removal surfaces 23 can be interpreted as removal surfaces of the removal surface pair and one or both of the second removal surfaces 24 can be interpreted as further removal surface(s). Conversely, the two second removal surfaces 24 can also form the removal surfaces of the removal surface pair and one or both first removal surfaces 23 then form the further removal surface(s). The terminology first/second removal surfaces 23/24 will continue to be used below

For mounting the chisel holder 20 on the in Figure 2 In the base holder 10 shown, the plug-in extension 40 is inserted into the plug-in receptacle 16.7 until the support body 21 rests with its first removal surfaces 23 on the first support surfaces 16.1 and with its second removal surfaces 24 on the second support surfaces 16.2 of the base holder 10. The removal surfaces 23, 24 and the associated support surfaces 16.1, 16.2 are each aligned accordingly. When the chisel holder 20 is fully inserted, the pressure screw 50 is screwed into the threaded receptacle 18 on the base holder 10. The pressure attachment 52 engages in the pressure screw receptacle 42 of the plug-in attachment 40 and rests against the pressure surface 42.1 at its end. The chisel holder 20 is thus axially blocked by the pressure screw 50. The pressure screw 50 presses its contact surfaces 41 against the wall of the plug-in receptacle 16.7 due to its orientation, which runs obliquely to the longitudinal extent of the plug-in projection 40. At the same time, the pressure screw 50 braces the first and second removal surfaces 23, 24 relative to the assigned first and second support surfaces 16.1, 16.2.

The removal surfaces 23, 24, which run at an angle to the plug-in extension 40, enable an optimized transfer of force to the base holder 10 in the event of transverse forces acting on the chisel holder 20 from different directions as well as varying forces acting against the feed direction V, since at least one of the removal surfaces 23, 24 is connected to its surface normal is aligned approximately in the direction of the acting, resulting force. The force transfer from the chisel holder 20 to the base holder 10 thus takes place to a large extent from the removal surfaces 23, 24 to the corresponding support surfaces 16.1, 16.2. This relieves the load on the plug-in attachment 40, particularly in its transition area to the support body 21. A premature fatigue fracture of the plug-in attachment 40 can thus be avoided.

Figure 5 shows a section of a tool system, each with a section of the holding section 30 of the bit holder 20, a support element 70 and a round shank bit 60 held in the bit holder 20.

A chisel head 61 of the round shank chisel 60 is completed with a collar 62 in the direction of the holding section 30 of the chisel holder 20. The collar 62 forms a support surface 62.1 in the direction of the holding section 30. This rests on a support surface 72 of the support element 70. The support surface 72 is formed within a receptacle 71 on the top of the support element 70. she is correspondingly delimited on the outside by an edge 71.1. On the sides opposite the support surface 72, the support element 70 has a seat surface 73 with which it rests on the wear surface 31 of the holding section 30 of the chisel holder 20. The support element 70 is constructed essentially rotationally symmetrical to a central longitudinal axis of the round shank chisel 60. The seat surface 73 merges via a circumferential recess 75 into a centering counter surface 74.1 of a centering projection 74 which runs inclined to the central longitudinal axis of the support element 70. How Figure 5 clearly illustrated, the centering projection 74 of the support element 70 is inserted into the correspondingly shaped centering receptacle 33 of the chisel holder 20. The centering counter surface 74.1 lies against a corresponding centering surface 33.1 of the centering receptacle 33. The shoulder 34 of the holding section 30 engages in the recess 75.

Along the central longitudinal axis, the support element 70 has a receiving bore 77, through which a guide area 76 for guiding the round shank chisel 60 is formed. In the assembly position shown, a centering section 63 of a chisel shank of the round shank chisel 60 is assigned to the guide area 76. In this way, a rotary bearing is created between the guide area 76 and the centering section 63. It is important to ensure that the outer diameter of the cylindrical centering section 63 is matched to the inner diameter of the receiving bore 77 in the guide area 76 so that free rotation between the support element 70 and the centering section 63 is maintained. The play between these two components should be chosen so that the smallest possible lateral offset (transverse to the central longitudinal axis of the round shank chisel (60)) occurs. After a taper area 63.1, the centering section 63 merges into the cylindrical chisel shaft, which is currently covered by a fastening sleeve 64.

The chisel shaft is held axially in the chisel holder 32 on the holding section 30 of the chisel holder 20 by means of the fastening sleeve 64. The holder allows axial play 80. The fastening sleeve 64 has a chamfer at its upper end.

During operation, the round shank bit 60 can rotate about its central longitudinal axis. The free rotation ensures that the round shank chisel 60 wears evenly over its entire circumference. The loosely placed support element 70, which is held by the centering section 63 of the chisel shaft, also rotates, whereby the rotatability of the round shank chisel 60 is further improved overall. Due to the rotation and the high mechanical load on the round shank chisel 60, the chisel holder 20 wears out, mainly in the upper section of the holding section 30. The wear surface 31 is abraded by the load. The existing wear of the holding section 30 can be assessed via the wear markings 30.1.

By engaging the centering attachment 74 in the centering receptacle 33 and the attachment 34 in the recess 75, lateral guidance of the support element 70 is achieved, which has a positive effect on the rotatability of the support element 70 and thus of the round shank chisel 60. The centering surface 33.1 merges tangentially into the surface of the extension 34. In the further course, the surface of the extension 34 is rounded and transferred into the wear surface 31. Correspondingly, the centering counter surface 74.1 of the centering projection 74 of the support element 70 merges tangentially into the recess 75 and the surface of the recess 75 merges rounded into the seat surface 73 of the support element 70. The rotatability of the support element 70 and thus the edges of the round shank chisel 60 are thus avoided. With its radially outer surface section, the approach 34 counteracts forces that act radially inwards on the support element 70. The radially inner surface section of the extension 34 counteracts radially outwardly directed forces. This reduces the force that must be absorbed by the centering surface 33.1 of the holding section 30, which leads to reduced surface pressure in this area and correspondingly to reduced wear. In addition, the guidance through the shoulder 34 counteracts a wobbling movement in the disk plane of the support element 70, which further reduces wear on the bit holder 20.

Figure 6 shows a schematic representation of the wear of the wear surface 31 of a known chisel holder 30 with an asymmetrical load on the support element 70, which is shaped complementary to the wear surface 31 and the centering receptacle 33. The disk-shaped support element 70 is in the embodiment shown by a flat support surface 72 and an opposite, also just designed seat 73 limited. The centering projection 74 is formed with its centering counter surface 74.1 all around the central receiving hole 77 on the seat surface 73. On the side of the support surface 72, the receiving bore 77 has an insertion phase 76.1. This makes it easier to insert the chisel shaft.

The asymmetrical load is represented by two arrows of different lengths, which symbolize a first force 83.1 and a comparatively larger second force 83.2. The asymmetric introduction of force can be caused, for example, by the position of the bit holder 20 in relation to the direction of rotation of the milling drum. Such an uneven axial load leads to asymmetrical wear on the wear surface 31 of the bit holder 20 in the event of a larger lateral movement (radial movement 82) of the support element 70. This is due to a wear surface inclined by a wear angle 84 relative to a plane running perpendicular to the central longitudinal axis M 31 indicated. The radial movement 82 is made possible if the lateral guidance of the support element 70 is inadequate. Due to such asymmetrical wear of the wear surface 31, the support element 70 guiding the round shank chisel 60 rests on the wear surface 31 at an angle to the central longitudinal axis M. The receiving hole 77 is therefore not exactly aligned with the central longitudinal axis M of the chisel holder 32. This misalignment can hinder or prevent the smooth rotation of the round shank chisel 60. Furthermore, the uneven wear of the wear surface 31 leads to severe longitudinal wear of the holding section 30.

The Figures 7 to 15 show in schematic side sectional views a section of a holding section 30 of the chisel holder 20 in the area of the centering receptacle 33. Of the rotationally symmetrical holding sections 30, only one half is shown up to the central longitudinal axis M of the holding section 30. The schematic representations are not to scale.

At the in Figure 7 In the embodiment shown, the centering surface 33.1 of the centering receptacle 33, which is aligned obliquely to the central longitudinal axis M, merges tangentially into the surface of the extension 34. The approach 34 is rounded at its outer end and transferred into the wear surface 31 of the holding section 30. The approach 34 is bead-shaped. It is arranged all around the centering receptacle 33. The approach 34 protrudes over the wear surface 31. The approach 34 forms a maximum point 37 at its highest point compared to the wear surface 31. The transition from the centering surface 33.1 into the cylindrical lateral surface of the chisel receptacle 32 forms an end 36 of the centering receptacle 33. In the present case, a centering height 81 marked by a double arrow indicates the distance measured in the direction of the central longitudinal axis M between the end 36 of the centering receptacle 33 and the maximum point 37 of the Approach 34.

The approach 34 has a first radius 86 in a range between 0.5 mm and 6 mm, in this case 1.5 mm. The height of the extension 34 relative to the wear surface 31 is preferably in a range between 0.3 mm and 2 mm, preferably between 0.5 mm and 1.5 mm, in the present case 1.0 mm. The approach 34 merges into the wear surface 31 via the rounded area with a second radius 87. The transition from the approach 34 to the centering surface 33.1 of the centering receptacle 33 is continuous. Edges between the centering surface 33.1, the extension 34 and the wear surface 31 are thus avoided, whereby the free rotation of a mounted support element 70 about the central longitudinal axis M is improved.

The approach 34 is formed onto the holding section 30 during the production of the chisel holder 20. When the tool system is mounted, it engages in the receptacle 75 of the support element 70, as shown in Figure 5 is shown. The inner diameter D _i 85 of the chisel holder 32 is marked by an arrow.

According to the invention, the centering height 81 is designed such that the ratio between the inner diameter D _i 85 of the chisel holder 32 and the centering height 81 has a value less than 8. The centering height 81 is given by the axial dimensioning of the centering receptacle 33 and the extension 34.

With a ratio of less than 8 between the inner diameter D _i 85 of the chisel holder 32 of the chisel holder 20 and the centering height 81, good lateral guidance of the support element 70 and thus of the round shank chisel 60 is ensured. In particular, the centering height 81 is designed in such a way that it is larger than the axial play 80 of the round shank chisel 60 and thus of the support element 70. The dimensioning of the centering height 81 depending on the inner diameter D _i 85 of the chisel holder 32 takes the larger permissible axial play 80 into account for larger tool systems. Thus, regardless of the tool size, sufficient lateral guidance of the support element 70 and thus of the round shank chisel 60 is always guaranteed.

Due to the counter-centering surface 74.1 of the centering projection 74 of the support element 70 resting against the centering surface 33.1 of the centering receptacle 33, good radial guidance of the support element 70 is achieved even when the round-shaft chisel 60 is maximally deflection from the chisel receptacle 32 within the permissible axial play 80. Through the in Figure 5 With the recess 75 shown and the extension 34 of the chisel holder 20 engaging therein, further lateral guidance of the support element 70 is achieved. Lateral movements or wobbling movements of the support element 70 can thus be safely avoided. As a result, the longitudinal wear of the holding section 30 of the chisel holder 20 can be significantly reduced. Asymmetrical wear of the wear surface 31 with an uneven load on the support element 70, such as this Figure 6 described can be avoided or at least significantly minimized. Due to the lack of angular displacement of the wear surface 31 relative to the central longitudinal axis M as a contact surface for the support element 70 and thus the round shank chisel 60, a consistently good rotation of the round shank chisel 60 and the support element 70 is achieved.

The easy rotation of the support element 70 and the round shank chisel 60 is further maintained by the rounded or continuous and therefore edge-free transitions between the centering surface 33.1, the shoulder 34 and the wear surface 31. Sharp transitions easily cause the support element 70 to tilt relative to the chisel holder 20, thereby preventing rotation. This can be avoided by using rounded or continuous transitions.

Figure 8 shows a holding section 30 in which, according to the invention, no shoulder 34 is provided which protrudes beyond the wear surface 31. At the in Figure 8 In the example shown of a holding section 30, a guide groove 35 is formed into the wear surface 31. The guide groove 35 runs around the centering receptacle 33 at a distance. It has a trapezoidal contour with side surfaces that are inclined to the wear surface 31. The approach 34 is formed between the centering receptacle 33 and the guide groove 35. It also has a trapezoidal contour. In the example shown, the extension 34 ends in the same plane as the wear surface 31 to the side of the guide groove 35. Towards the central longitudinal axis M, the extension 34 merges directly into the inclined centering surface 33.1 of the centering receptacle 33. Here too, as in all embodiments described below, the centering receptacle 33 is completed by the end 36 formed in the transition from the centering surface 33.1 to the lateral surface of the chisel receptacle 32.

On the seat 73 of an in Figure 8 Supporting element 70, not shown, which is adapted to the frontal contour of holding section 30, a guide web is formed on seat surface 73 all around the centering projection 74. The The guide web has a contour that is complementary to the guide groove 35. When the tool system is installed, the guide bar engages in the corresponding guide groove 35. This results in further lateral guidance of the support element 70. In this way, wobbling movements of the support element 70 can be largely avoided. The longitudinal wear of the holding section 30 can be further reduced by the guide groove 35 and a guide web engaging therein.

The centering height 81 is measured in the direction of the central longitudinal axis M between the end 36 of the centering receptacle 33 and the upper surface of the extension 34, as shown by a double arrow. The ratio between the inner diameter D _i 85 of the chisel holder 32 and the centering height 81 is selected to be less than 8, in this case less than 6.5. This ensures good lateral guidance of the support element. With a ratio of less than 6.5, sufficient lateral guidance is achieved even towards the end of the service life of the support element 70 and the round shank chisel 60, if the axial play 80 of the round shank chisel 60 is possibly increased due to the wear that has already occurred.

Deviating from the example shown, the transition from the centering surface 33.1 to the shoulder 34 and/or the transition from the shoulder 34 to the adjacent side surface of the guide groove 35 and/or the transition from the opposite side surface of the guide groove 35 to the adjacent wear surface 31 can be rounded be. The transitions from the side surfaces to the groove bottom can also be rounded off. Sharp edges can be avoided in this way. This leads to improved rotatability of the support element 70.

At the in Figure 9 In the chisel holder 20 shown, a trapezoidal guide groove 35 is also formed into the wear surface 31. A projection 34 formed between the guide groove 35 and the centering receptacle 33 has a bead-shaped contour. The radius of the extension 34 is chosen so that its surface is tangential to the centering surface 33.1 of the centering receptacle 33 and oppositely merges into the adjacent side surface of the guide groove 35. The centering height 81 corresponds to the distance measured in the direction of the central longitudinal axis M between the end 36 of the centering receptacle 33 and the maximum point 37 of the extension 34. The immediately successive combination of the centering receptacle 33, the extension 34 and the guide groove 35 results in a corresponding The seat surface 73 of a support element 70 shaped for this purpose achieves good lateral guidance of the support element 70.

The wear surface 31 of the in Figure 10 Holding section 30 shown goes directly into the centering surface 33.1 of the centering receptacle 33. In the outer region of the wear surface 31, a bead-shaped extension 34 is molded onto it. The centering height 81 is measured along the central longitudinal axis M between the end 36 of the centering receptacle 33 and the maximum point 37 of the approach 34. The attachment 34, which is arranged comparatively far outside on the holding section 30, results in particularly good stabilization of the rotational movement of a correspondingly designed, adjacent support element 70.

In Figure 11 a holding attachment 30 is shown with a multi-stage surface facing a support element 70 (not shown). The centering surface 33.1 merges into a contact surface 38 arranged transversely to the central longitudinal axis M, in particular perpendicular to the central longitudinal axis M. The contact surface 38 is adjoined by a projection 34 which projects beyond the contact surface 38. The surface of the bead-shaped extension 34 merges tangentially into the adjacent side surface of a trapezoidal guide groove 35. The wear surface 31 is arranged all around the guide groove. The contact surface 38, the maximum point 37 of the extension 34, the groove bottom of the guide groove 35 and the wear surface 31 are arranged at different levels along the central longitudinal axis M. The maximum point 37, measured parallel to the central longitudinal axis M, is the furthest away from the end 36 of the centering receptacle 33, followed by the contact surface 38, the wear surface 31 and the groove bottom of the guide groove 35. Due to this course of the front surface of the Holding section 30 provides very good lateral guidance corresponding to this trained support element 70 is achieved. Both lead to reduced wear on the holding section 30 and thus on the chisel holder 20.

At the in Figure 12 In the exemplary embodiment of the chisel holder 20 shown, lugs 34 arranged concentrically to one another are formed on the holding section 30 around the centering receptacle 33. A wavy contour is thus formed, the surface of which represents the wear surface 31. The centering height 81 is measured between the end 36 of the centering receptacle 33 and the maximum point 37 of the innermost extension 34. For adjacent approaches 34 of different heights, the centering height 81 is preferably determined at the maximum point 37 of the highest approach 34. The lugs 34 arranged all around the centering receptacle 33 ensure good rotatability of a corresponding support element 70. Due to the wave-shaped contour, the surface of the holding section 30 projected in the axial direction remains equal to a flat surface, so that the axial supporting effect is maintained. The radially effective area is significantly increased by the side flanks of the approaches 34. This means that lateral forces can be better absorbed. The wave shape increases the contact area between a support element 70 and the holding section 30 of the bit holder 20. This leads to reduced wear on the chisel holder 20 and to improved rotatability of the support element 70 and thus of the round shank chisel 60.

Figure 13 shows a section of a chisel holder 20 with a flat wear surface 31, onto which two concentric, bead-shaped projections 34 are formed. This arrangement also achieves good rotation and good lateral stabilization.

The in Figure 14 Chisel holder 20 shown has a wear surface 31 that runs in a straight line but is oriented obliquely to the central longitudinal axis M. The maximum point 37 is formed in the rounded transition area from the centering surface 33.1 into the wear surface 31. Due to their orientation obliquely to the central longitudinal axis M, both the centering surface 33.1 and the wear surface 31 have a radially stabilizing effect on the position of a device in its contour Seat surface 73 of the support element 70 adapted to the wear surface 31. The centering height 81 is measured in the direction of the central longitudinal axis M from the end 36 of the centering receptacle 33 to the maximum point 37 at the transition from the centering surface 33.1 to the wear surface 31.

Figure 15 shows a holding section 30 in which, according to the invention, no shoulder 34 is provided which protrudes beyond the wear surface 31. At the in Figure 15 In the chisel holder 20 shown, the wear surface 31 runs obliquely to the central longitudinal axis M of the holding section 30. The largest distance measured in the direction of the central longitudinal axis M between the end 36 of the centering receptacle 33 and the wear surface 31 results from the outer edge of the holding section 30, so that this distance is the centering height 81 forms. In this example, too, both the centering surface 33.1 and the wear surface 31, which is aligned obliquely to the central longitudinal axis M, have a radially stabilizing effect on a correspondingly shaped, adjacent support element 70.

In summary, it can be said that through the inventive design of the holding section 30 of the chisel holder 20, in which the ratio between the inner diameter D _i 85 of the chisel holder 32 and the centering height 81 is less than 8 and / or in which the centering height 81 is greater than an axial Play 80 of a round shank chisel 60 mounted in the chisel holder 20, the longitudinal wear of the holding section 30 can be significantly reduced with respect to the operating time of the tool system. Tilting of the round shank chisel 60 during startup can be virtually avoided due to the improved and more stable engagement of the lug(s) 34 in corresponding recesses 75 of a support element 70. The length wear of the holding section 30 is thereby evened out. The chisel shaft and the chisel holder 32 are better protected from contamination by the increased sealing effect of the support surface between the support element 70 and the holding section 30. This also leads to significantly reduced wear on the bit holder 20 in the area of its holding section 30. By designing the removal surfaces 23, 24 to rest on correspondingly designed support surfaces 16.1, 16.2 of the base holder 10, a Premature wear or fatigue fracture of the plug-in extension 40 of the chisel holder 20 can be avoided. The measures can significantly increase the life expectancy of the chisel holder 20 as a structural unit. This leads to reduced maintenance and spare parts costs.

Claims (12)

1. A bit holder (20) for an earth working machine having a support body (21) on which is shaped, in the region of a working side, a holding portion (30) that comprises a bit receptacle (32); the holding portion (30) being terminated at its end facing away from the support body (21) by a wear surface (31), enclosing the bit receptacle (32), for abutment of a round-shank bit (60) or of a support element (70); the bit receptacle (32) being transitioned indirectly or directly into the wear surface (31) via a centering surface (33.1), oriented obliquely to the longitudinal center axis (M) of the bit receptacle (32), of a centering receptacle (33); and an insertion projection (40) being shaped onto the support body (21) on the side located oppositely from the holding portion (30),

   wherein a centering height (81), measured in the direction of the longitudinal center axis (M), which extends between an end (36) of the centering receptacle (33) facing away from the wear surface (31) and a maximum point (37) of a projection (34) projecting beyond the wear surface (31), is designed in such a way that the ratio between the inside diameter (85) of the bit receptacle (32) and the centering height (81) is less than 8; and the support body (21) comprises one or several clearing surfaces on its side facing away from the holding portion (30),

   the one clearing surface (23, 24) extending on both sides of a center plane that receives the center axis (M) and extends in the advance direction (V); or at least one clearing surface (23, 24) respectively extends on both sides of that center plane.
2. The bit holder (20) according to Claim 1, wherein the ratio between the inside diameter (85) of the bit receptacle (32) and the centering height (81) is less than 7.5, preferably less than 7.0, particularly preferably less than 6.5.
3. The bit holder (20) according to Claim 1 or 2, wherein the projection (34) is arranged surroundingly with respect to the bit receptacle (32).
4. The bit holder (20) according to one of Claims 1 to 3, wherein several projections (34) of the same or different height are shaped onto the wear surface (31) of the holding portion (30); and the ratio between the inside diameter Di (85) of the bit receptacle (32) and the centering height (81) with respect to one of the projections (34), preferably the ratio between the inside diameter Di (58) of the bit receptacle (32) and the greatest centering height (81) determined with respect to a projection (35), is less than 8.
5. The bit holder (20) according to one of Claims 1 to 4, wherein a guidance groove (35) is shaped into the adjacent wear surface (31), spaced away from and surroundingly with respect to the centering receptacle (33).
6. The bit holder (20) according to Claim 5, wherein the projection (34) is embodied between the centering receptacle (33) and the guidance groove (35); and the centering receptacle (33) has, with respect to the adjacent wear surface (31), a greater depth than the guidance groove (35).
7. The bit holder (20) according to one of Claims 1 to 6, wherein transitions between the centering surface (33.1), the wear surface (31), the projection (34), and/or the guidance groove (35) proceed in continuous or rounded fashion.
8. The bit holder (20) according to one of Claims 1 to 7, wherein the height of the projection (34) with respect to the wear surface (31) is greater than or equal to 0.3 mm, preferably between 0.3 mm and 2 mm, particularly preferably between 0.5 mm and 1.5 mm.
9. The bit holder (20) according to one of Claims 1 to 8, wherein the inside diameter Di (85) is equal to 20 mm and the centering height (81) is greater than 2.5 mm; or the inside diameter Di (85) is equal to 22 mm and the centering height (81) is greater than 2.75 mm; or the inside diameter Di (85) is equal to 25 mm and the centering height (81) is greater than 3.125 mm; or the inside diameter Di (82) is equal to 42 mm and the centering height (81) is greater than 5.25 mm.
10. The bit holder (20) according to one of Claims 1 to 9, wherein the projection (34) and/or the guidance groove (35) is produced on the wear surface (31) by way of a material-removing production method, in particular turning, sinking, milling, in the context of manufacture of the bit holder (20).
11. The bit holder (20) according to Claim 10, wherein the projection (34) and/or the guidance groove (35) is produced on the wear surface (31) by way of turning, sinking, milling, in the context of manufacture of the bit holder (20).
12. The bit holder (20) according to one of Claims 1 to 11, wherein the support body (21) comprises at least one further clearing surface (23, 24) that is at an angle to the two clearing surfaces (23, 24) of the clearing-surface pair.

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