EP2646652B1 - Chisel 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 to which a plug-in attachment is connected directly or indirectly to one plug-in attachment side, the plug-in attachment having at least one convex contact surface and a pressure surface.

Such a chisel holder is from EP 0 771 911 A1 known. The chisel holder has a plug-in attachment with a frusto-conical outer geometry. The chisel holder can be inserted with the plug-in attachment in a base part that is attached to the surface of a milling drum tube. To fix the chisel holder, a pressure screw is used that acts on the plug-in attachment. The plug-in attachment is clamped in a receiving bore of a chisel holder with the pressure screw. During operation, high machining forces are diverted into the base part via the chisel holder. The round shaft cross-section of the plug-in attachment prevents forces from being transmitted in the circumferential direction of the plug-in attachment.

However, strong alternating loads are introduced into a machining tool held in the chisel holder and transferred to the base part. These alternating stresses load the mating surfaces between the chisel holder and the base part. In particular when milling very hard floor coverings, such as concrete surfaces, it can happen that the seating surfaces between the chisel holder and the base part expand or knock out. Then the secure hold of the chisel holder in the base part is no longer guaranteed. In particular, the base part then still has to be replaced, which is associated with a high expenditure on parts and assembly.

Chisel holders are therefore used which allow a certain readjustment of the chisel holder in the base part even in the event of wear, in order to achieve a long service life.

Such a chisel holder is in the DE 43 22 401 A1 shown. A pentagonal plug-in attachment is inserted into a correspondingly configured plug-in receptacle of a base part.

The chisel holder is supported with a support surface of its support body on a counter surface of the base part in order to be able to dissipate a large part of the stresses. With the pentagonal cross-section of the plug-in attachment, transverse forces occurring during the machining process are introduced into the base part via the plug-in attachment. In addition to the desired tensile stresses and the unavoidable bending stresses, this also creates torsional stresses in the plug-in attachment. This results in a multiaxial stress state.

DE 10 2004 057 302 A1 shows another chisel holder.

The object of the invention is to create a chisel holder of the type mentioned at the outset, with which the machining forces can be transferred to a base part in a stress-optimized manner during the machining operation.

This object is achieved in that the plug-in attachment has two convex contact surfaces which are arranged at a distance from one another. The use of two convex contact surfaces creates two contact areas that ensure reliable support. In addition, the two contact surfaces enable the implementation of a statically determined clamping system.

Even if there is surface wear, the two contact surfaces can readjust themselves on the corresponding mating surfaces of the base part, so that the chisel holder can be retightened. Furthermore, it is then also possible to replace a worn bit holder in an existing base part.

According to a preferred embodiment of the invention, it can be provided that the contact surfaces are arranged at a distance from one another by means of a recess in the plug-in attachment. This recess can be produced in a simple manner in terms of production technology, so that the chisel holder can be produced with little effort.

The contact surfaces preferably have the same radius of curvature or the same geometry of curvature, so that a simple geometry of the counter surfaces of the base part into which the plug-in attachment is inserted becomes possible.

The two contact surfaces are particularly preferably arranged symmetrically to the central longitudinal axis of the plug-in attachment, so that a symmetrical force dissipation is possible.

The contact surfaces are particularly preferably located on the same pitch circle. Furthermore, it can be provided that the contact surfaces have the same center of curvature, so that production is further simplified. For example the contact surfaces can be turned over in one setting or processed in some other way.

It has been shown that the radius of curvature of the contact surfaces should be in the range between 16 mm and 32 mm. In the case of smaller curvature radii, excessive surface wear is to be feared in the case of high loads. If the radius of curvature is too large, reliable tensioning of the plug-in attachment on the pressure surface can be problematic. In particular, it is advantageous if the radius is a constant radius over the length of the contact surfaces, so that a partially cylindrical geometry of the contact surfaces is established. This measure enables a simple design of the plug-in receptacle of a base part into which the plug-in attachment is inserted.

It has been shown that for the required applications in soil cultivation machines, the extension of the contact surfaces in the direction of the plug-in attachment should be in the range between 20 mm and 50 mm. Then the clamping forces are transferred from the chisel holder to the base part with optimized surface pressure. The extension of the contact surfaces in the circumferential direction should then be in the range between 30 ° and 80 °.

A chisel holder according to the invention can be designed in such a way that the contact surfaces merge via a convex transition region into the recess, which is concave in at least some regions. This creates a stress-optimized plug attachment cross-section.

A chisel holder according to the invention can be characterized in that the contact surfaces are arranged at least in some areas in the area of the front of the plug-in attachment facing the tool advance direction and the pressure surface in the area of the rear of the plug-in attachment.

In order to obtain a symmetrical force distribution, it can be provided that the contact surfaces are arranged symmetrically to the central transverse plane of the plug-in extension running in the direction of the central longitudinal axis of the plug-in attachment, and / or that the pressure surface is arranged symmetrically to this central transverse plane. With the symmetrical arrangement of the contact surfaces and the pressure surface as well as the division of the contact surface into a pair of spaced-apart partial surfaces, the reaction force to the pressing force, which is introduced via the pressure surface, is divided into a force pair, with the vectors of the reaction force pair and the vector of the pressing force forming a system form, in which the vectors run towards each other in a star shape and take the plug-in attachment in the middle.

In order to be able to exert a sufficient pull-in force on the plug-in attachment via the pressure surface, it can be provided that the pressure surface is at least 20 mm (distance A) from the connection area of the plug-in attachment to the support body. It is also conceivable for this purpose that the contact surfaces are arranged at least 15 mm (distance dimension B) from the connection area of the plug-in attachment to the support body.

Within the scope of the invention it can also be provided that the center of gravity of at least one of the contact surfaces in the direction of the central longitudinal axis of the plug-in attachment is not more than 20 mm (distance C) from the center of gravity of the pressure surface. Sufficiently high clamping forces can then be generated. This also creates a balance of forces which enables clean "sliding" between the plug-in attachment and the base part, with the radial components of the clamping force also being absorbed via the contact surfaces.

If it is provided that the contact surfaces are formed by support sections which are raised compared to the actual plug-in attachment, then on the one hand a defined contact geometry is created in the transition area to the base part. On the other hand, the contact surfaces can work on the support sections, but the defined system geometry is retained. In addition, this also simplifies production.

To generate a sufficiently high pull-in force in the direction of the central longitudinal axis of the plug-in attachment and at the same time a clamping force acting perpendicular to the central longitudinal axis, the invention provides that the normal on the pressure surface is at an angle between 30 ° and 70 ° to the central longitudinal axis of the plug-in attachment.

Figur 1

eine Kombination eines Basisteils und eines Meißelhalters in perspektivischer Seitenansicht;

Figur 2

die Darstellung gemäß Figur 1 in Explosionsansicht;

Figur 3

den Meißelhalter gemäß den Figuren 1 und 2 in Frontansicht;

Figur 4

den Meißelhalter gemäß den Figuren 1 bis 3 in Rückansicht;

Figur 5

den Meißelhalter gemäß den Figuren 1 bis 4 in Seitenansicht von links;

Figur 6

die Darstellung gemäß Figur 5 im Vertikalschnitt durch die Mittelquerebene des Meißelhalters;

Figur 7

den Meißelhalter gemäß den Figuren 1 bis 6 in Seitenansicht von rechts und teilweise im Schnitt;

Figur 8

einen in Figur 5 mit VIII-VIII markierten Schnittverlauf;

Figur 9

einen in Figur 7 mit IX-IX markierten Schnittverlauf;

Figur 10

einen in Figur 7 mit X-X markierten Schnittverlauf;

Figur 11

die Werkzeugkombination gemäß Figur 1 in Draufsicht;

Figur 12

einen in Figur 11 mit XII-XII markierten Schnittverlauf;

Figur 13

den Meißelhalter gemäß Figur 5 in Ansicht von vorne;

Figur 14

den Meißelhalter in Ansicht von hinten; und

Figur 15

den Meißelhalter in einer gedrehten Seitenansicht.

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

Figure 1

a combination of a base part and a chisel holder in a perspective side view;

Figure 2

the representation according to Figure 1 in exploded view;

Figure 3

the chisel holder according to the Figures 1 and 2 in front view;

Figure 4

the chisel holder according to the Figures 1 to 3 in rear view;

Figure 5

the chisel holder according to the Figures 1 to 4 in side view from the left;

Figure 6

the representation according to Figure 5 in vertical section through the central transverse plane of the chisel holder;

Figure 7

the chisel holder according to the Figures 1 to 6 in side view from the right and partially in section;

Figure 8

one in Figure 5 section line marked VIII-VIII;

Figure 9

one in Figure 7 cutting line marked with IX-IX;

Figure 10

one in Figure 7 cutting line marked with XX;

Figure 11

the tool combination according to Figure 1 in plan view;

Figure 12

one in Figure 11 with XII-XII marked cutting course;

Figure 13

the chisel holder according to Figure 5 in front view;

Figure 14

the chisel holder in a view from behind; and

Figure 15

the chisel holder in a rotated side view.

Figure 1 shows a tool combination consisting of a base part 10 and a chisel holder 20. The chisel holder 20 is interchangeably connected to the base part 10. The base part 10 has a solid base body 13 which has a lower connection side 11. This connection side 11 has a concave curvature, the curvature being selected in accordance with the outer diameter of a milling drum tube. The base part 10 can thus be placed with its connection side 11 on the outside of the milling drum tube and welded to it. The base body 13 has a projection on the front side which is delimited on the side by inclined surfaces 14 and on the front side by inclined surfaces 15. The inclined surfaces 15 are set at an angle to one another and the inclined surfaces 14 adjoin the inclined surfaces 15 at an angle. This results in an arrow-shaped geometry of the base part 10 at the front, which leads to a better clearing effect of the base part 10.

As the Figure 2 illustrates, a chisel holder receptacle 16 with a plug-in receptacle 16.7 is incorporated into the base part 10. The plug-in receptacle 16.7 penetrates the base body 13 completely and thus opens into the connection side 11 In the base part 10, a threaded receptacle 18 is incorporated, which opens into the plug-in receptacle 16.7 (see Figure 12 ). The chisel holder receptacle 16 has first support surfaces 16.1 and second support surfaces 16.2. The first support surfaces 16.1 form a first support surface pair and the second support surfaces 16.2 form a second support surface pair. The supporting surfaces 16.1, 16.2 are each arranged at an angle to one another in each supporting surface pair. Furthermore, the support surfaces 16.1 are each set at an angle to the support surfaces 16.2, so that an obtuse-angled chisel holder receptacle 16 results. In the transition area between the individual support surfaces 16.1 and 16.2, additional spaces 16.3, 16.4, 16.5 are provided in the form of recesses. In the area of the readjustment space 16.5, a recess 16.6 is also provided, which creates a transition from the bit holder receptacle 16 to the thread receptacle 18.

How Figure 2 can further be seen, a surface 17 is formed around the entry into the threaded receptacle 18, which is laterally bounded by inclined surfaces, the inclined surfaces opening in a divergent manner towards the rear of the base part 10. In this way, the surface 17 and thus a tool holder 43 of a pressure screw 40 can be easily cleaned. The pressure screw 40 has a threaded section 41 with which it can be screwed into the threaded receptacle 18. Furthermore, the pressure screw 40 is designed with a pressure shoulder 42 in the form of a truncated conical pin which is integrally formed on the threaded section 41.

How Figure 2 further shows, the chisel holder 20 can be connected to the base part 10. The chisel holder 20 has a support body 21 which is equipped with an apron 22 on the front. The apron 22 carries a web 22.1, formed in one piece, which rises upwards from the apron 22. A projection 23 is also coupled in one piece to the support body 21 and terminates in a cylindrical section 24. The cylindrical section 24 is provided with wear marks, which in the present case are designed as circumferential grooves 26. The cylindrical portion 24 terminates with a support surface 25 which concentrically the bore entry of a Chisel holder 27 revolves. The chisel receptacle 27 merges into the support surface 25 via a bevel-shaped insertion section 27.1.

How Figure 4 shows, the chisel receptacle 27 is designed as a through hole. The support body 21 is provided with a rear recess which serves as a flushing channel 28. The flushing channel 28 consequently opens the chisel receptacle 27 radially outward in the region of its bore exit. Thus, debris particles that have entered the chisel receptacle 27 during the use of the tool can be conveyed out radially through the flushing channel 28.

Figure 3 shows that the support body 21 has first removal surfaces 29.1 in the area of the skirt 22. These removal surfaces 29.1 are at an obtuse angle ε ₁ to one another (see Figure 13 ) and are connected to one another via a transition section 29.2. The angle ε ₁ between the first removal surfaces 29.1 corresponds to the angle between the first support surfaces 16.1 of the base part 10.

Figure 4 shows that the back of the support body 21 has downwardly facing second removal surfaces 29.4. The second removal surfaces 29.4 are at an angle ε ₂ to one another (see Figure 14 ), the angle ε ₂ between the second removal surfaces 29.4 here also corresponding to the angle between the second support surfaces 16.2 of the base part 10. While the first removal surfaces 29.1 merge into one another by means of the transition section 29.2, a transition area is formed between the second removal surfaces 29.4 by the flushing channel 28 and a transition section 29.5.

The removal surfaces 29.1 and 29.4 each form pairs of removal surfaces in the form of a prism. These prisms have a central longitudinal axis MLL, which is formed in the bisector plane between the two first removal surfaces 29.1 and the second removal surfaces 29.4. In the Figures 13 and 14 these bisector planes are marked with WE. The central longitudinal axis is indicated there with MLL, whereby the central longitudinal axis MLL can in principle be at any position within the bisector plane.

The Figures 3 and 4 show in conjunction with the Figures 13 and 14 that the first removal surfaces 29.1 and also the second removal surfaces 29.4 diverge starting from the plug-in attachment side towards the processing side. In the present example, the surface normals correspondingly converge on the removal surfaces 29.1, 29.4 from the plug-in attachment side to the processing side. The surface normals therefore converge in the area of the tool engagement point in which the machining forces are introduced into the tool system.

The use of two pairs of removal surfaces, each with the first and second removal surfaces 29.1 and 29.4, takes optimal account of the variance of the machining forces during tool engagement. A comma span is created while the tool is being used. With this chip formation, not only the amount of force changes, but also the direction of force. Accordingly, at the beginning of the tool engagement, the machining force acts in such a way that it is more likely to be diverted via the pair of removal surfaces formed by the first removal surfaces 29.1. As the tool engagement progresses, the direction of the machining force rotates and is then increasingly diverted via the pair of removal surfaces formed by the second removal surfaces 29.4. Accordingly, the angle y '(see Figure 5 ) be designed between the pairs of removal surfaces so that the variance of the machining force is taken into account, and this machining force always acts on the prisms formed by the pairs of removal surfaces.

In the Figures 3 and 9 the central transverse plane MQ of the bit holder 20 is marked. The chisel holder is mirror-symmetrical to this central transverse plane MQ so that it can be installed on a milling drum as a right or left part

In the Figures 3 and 4 the feed direction is marked with the usual arrows. The bit holder sides are arranged transversely to the feed direction.

The surface normals of the removal surfaces 29.1 and 29.4 thus each point to their side of the chisel holder viewed in the tool advance direction and downwards, as can be seen from FIGS Figures 3 and 4 becomes clear. In Figure 5 this fact is shown again in a side view.

However, the processing force does not only act in the direction of the image plane Figure 5 , but also in the transverse direction. These transverse force components are then ideally absorbed by the angular inclination (ε ₁ , ε ₂ ) of the removal surfaces 29.1, 29.4. Since the machining forces scatter less in the transverse direction at the beginning of the tool engagement, the angle ε _{1 can} also be selected to be smaller than ε ₂ .

Figure 5 further shows that a plug-in projection 30 is formed in one piece on the support body 21 and merges into the first removal surfaces 29.1 and the second removal surfaces 29.4 via a rounded transition 29.3. The plug attachment 30 is arranged in such a way that it essentially, in the present case around 90%, adjoins the support body 21 in the area of the first removal surfaces 29.1. The plug-in attachment 30 carries two contact surfaces 31.1 on the front. These are how Figure 3 can be seen, formed as convex cylinder surfaces. The contact surfaces 31.1 extend longitudinally and parallel to the central longitudinal axis M (see FIG. Figure 5 ) of the plug-in attachment 30. The contact surfaces 31.1 are therefore also parallel to one another. The contact surfaces 31.1 are arranged at a distance from one another in the circumferential direction of the plug-in attachment 30. They have the same radius of curvature and are arranged on a common pitch circle. The radius of curvature corresponds to half the pitch circle diameter. A recess 31.2 is provided in the area between the contact surfaces 31.1, the contact surfaces 31.1 running parallel to the recess 31.2. The recess can have a wide variety of shapes, for example a simple surface. In the present exemplary embodiment, the recess 31.2 forms a depression which is concave between the contact surfaces 31.1. The concavity is designed so that a partially cylindrical geometry results. The recess 31.2 does not extend over the entire length of the plug-in attachment 30, but only over a partial area, like this Fig. 13 detect leaves. The recess 31.2 is open to the free end of the plug attachment 30, that is, in the plugging direction. The recess 31.2 also opens radially outwards without undercuts. Opposite the contact surfaces 31.1, the plug-in projection 30 has a pressure screw receptacle 32 on the rear side, which is equipped with a pressure surface 32.1.

Figures 6 and 9 illustrate that the recess 31.2 between the two contact surfaces 31.1 has a concavely curved geometry, and in particular can form a partially cylindrical cross section.

In the Figures 7 to 10 the design of the plug-in attachment 30 is detailed. FIG. 9 clearly shows the concave bulge of the recess 31.2, which adjoins the convex contact surfaces 31.1. Out Figure 10 it becomes clear that the plug-in attachment 30 has a substantially circular or oval cross-sectional configuration in its area adjoining the contact surfaces 31.1. Figure 8 illustrates the area of the pressure screw receptacle 32, the pressure surface 32.1 being set at an angle δ to the central longitudinal axis M of the plug-in attachment 30. This setting angle δ is preferably in the range between 20 ° and 60 ° in order to achieve an optimal pull-in effect of the chisel holder 20.

Figure 7 further shows that the pressure surface 32.1 is arranged at a distance A from the connection area of the plug-in attachment 30 to the support body 21.

The contact surfaces 31.1 are spaced apart by the distance B from the connection area of the plug-in attachment 30 to the support body 21. The centroid of the contact surfaces 31.1 is arranged at a distance C from the centroid of the pressure surface 32.1.

To mount the chisel holder 20 in the base part 10, the plug-in attachment 30 is inserted into the plug-in receptacle 16.7. The insertion movement is carried out with the first and limited second removal surfaces 29.1, 29.4 which strike the first and second support surfaces 16.1, 16.2.

As the Figures 1 and 12 can be seen, the assignment is made in such a way that the transition section 29.2 is above the supplementary space 16.4, the supplementary space 16.5 is bridged by the transition section 29.5 and the lateral supplementary spaces 16.3 are bridged by the angular area between the first and second removal surfaces 29.1, 29.4 is formed. The spacing of the chisel holder 20 in the area of these readjusting spaces 16.3, 16.4, 16.5 ensures that the chisel holder 20 can move into the readjusting spaces 16.3, 16.4, 16.5 during the machining operation when the removal surfaces 29.1, 29.4 and / or the support surfaces 16.1 , 16.2 process. This applies in particular when worn chisel holders 20 are exchanged for new ones with an existing base part 10. To fix the prescribed installation state, the pressure screw 40 is screwed into the threaded receptacle 18. The pressure shoulder 42 presses itself with its flat end surface onto the pressure surface 32.1 and thus creates a pull-in force which acts in the direction of the central longitudinal axis M of the plug-in attachment 30. At the same time, however, the pressure screw 40 is also positioned at an angle to the central longitudinal axis M of the plug-in attachment 30 that a clamping force acting in the direction towards the front is also introduced into the plug-in attachment 30. This clamping force is transmitted via the contact surfaces 31.1 into the corresponding concave counter surface of the cylindrical section of the plug-in receptacle 16.7. The spacing of the contact surfaces 31.1 via the recess 31.2 guarantees that the plug-in attachment 30 is reliably fixed via the two support areas formed laterally by the contact surfaces 31.1. In this way, the surface pressures that occur are kept low, in particular over the two contact surfaces 31.1, which leads to a reliable fixation of the plug-in attachment 30.

Because the chisel holder 20 can be readjusted into the readjustment spaces 16.3, 16.4, 16.5 in the event of wear, effective wear compensation can be made, with the removal surfaces 29.1, 29.4 supporting surfaces 16.1, 16.2 at every point so that in the event of wear and tear, the support surfaces 16.1, 16.2 are worn evenly without a so-called beard or burr arising. This configuration is particularly advantageous when the base part 10, as is usually required, has a service life that lasts several life cycles of the bit holders 20. Unworn chisel holders 20 can then always be securely clamped and held on a partially worn base part 10. The repair of a machine in which the tool system formed from the base part 10 and chisel holder 20 is used is thus also simple. A large number of tool systems are usually mounted on such a machine, for example a road milling machine or a surface miner. The base part is usually welded onto the surface of a milled roller tube. If all or some of the chisel holders 20 are now worn, they can simply be exchanged for new unworn or partially worn chisel holders 20 (which can be used, for example, for rough removal work).

When replacing, the pressure screw 40 is first loosened. The worn chisel holder 20 with its plug-in attachment 30 can then be pulled out of the plug-in receptacle 16.7 of the base part 10 and removed. Then the new (or partially worn) chisel holder 20 is inserted with its plug-in attachment 30 into the plug-in receptacle 16.7 of the base part 10. The pressure screw 40 can now be replaced with a new one if necessary. It is then screwed into the base part 10 and braced with the chisel holder 20 in the manner described above.

Figure 12 shows that the base part 10 carries a projection 50 which protrudes into the plug-in receptacle 16.7. In the present case, this projection 50 is formed by a cylinder pin which is driven into a partially cylindrical recess 19 from the connection side 11. The partially cylindrical recess 19 surrounds the cylinder pin by more than 180 ° of its circumference, so that it is held captive. The area of the cylindrical pin protruding into the chisel receptacle 27 engages in the recess 31.2 between the contact surfaces 31.1. When inserting the plug-in attachment 30 into the plug-in receptacle 16.7, the projection 50 threads into the free end of the plug-in extension 30 reliably a recess 31.2 open. An alignment of the chisel holder 20 with respect to the base part 10 is thus achieved. This alignment guarantees that the first and second removal surfaces 29.1, 29.4 now come to rest precisely on the support surfaces 16.1, 16.2, so that incorrect assembly is excluded. Furthermore, the projection 50 and the geometrically adapted recess 31.2 in the form of a key-lock principle prevent an incorrect chisel holder 20 from being accidentally installed on the base part 10.

The angular relationships of the bit holder 20 according to the invention will be discussed in greater detail below.

Figure 5 shows that the central longitudinal axis 24.1 of the chisel holder 27 is at an angle α or ϕ to the longitudinal alignment of the transition section 29.2 or 29.5 and thus also to the central longitudinal axis MLL of the prism formed by the first removal surfaces 29.1 and the second removal surfaces 29.4. The angle α can be between 40 ° and 60 ° or ϕ in the range between 70 ° and 90 °.

Figure 5 also shows that when the removal surfaces 29.1 and 29.4 are projected into a plane transverse to the feed direction (projection corresponding to Figure 5 ) the removal surfaces 29.1 and 29.4 are angled to one another at an angle γ in the range between 40 ° and 60 °, or that the opening angle between the transition sections 29.2 and 29.5 in the longitudinal direction according to Figure 5 is between 120 ° and 140 °. Correspondingly, the angle γ 'between the central longitudinal axes MLL of the two prisms formed by the removal surfaces 29.1 and 29.4 (removal surface pairs) is in the range between 120 ° and 140 °. Furthermore, with such a projection of the removal surfaces 29.1, 29.4, the first removal surfaces 29.1 are at an angle β and the second removal surfaces 29.4 at an angle µ to the central longitudinal axis M of the plug-in attachment 30. The same applies here to the central longitudinal axes MLL of the prisms. The angles β and μ can be in the range between 100 ° and 130 °, preferably in the range between 110 ° and 120 °.

Figure 13 shows that the first removal surfaces 29.1 enclose an angle ε ₁ . This angle ε ₁ should preferably be in the range between 100 ° and 120 °. The bisector of this angle ε ₁ lies in a plane and Figure 13 shows that the plug attachment 30 is arranged symmetrically to this plane.

In the same way, the rear, second removal surfaces 29.4 are also made at an angle ε ₂ corresponding to one another, like this Figure 14 shows. However, the angle ε ₂ can deviate from the angle ε ₁ and in the present exemplary embodiment can be between 120 ° and 140 ° and the plug-in attachment 30 is also arranged and equipped symmetrically to the bisector plane of this angle ε ₂ .

Figure 15 shows that a first removal surface 29.1 of the first removal surface pair and a second removal surface 29.4 of the second removal surface pair are positioned at an angle ω to one another and form a support area.

Claims (16)

1. A bit holder for a soil working machine, in particular a road milling machine, with a support body (21) to which a plug-in projection (30) is directly or indirectly connected on a plug-in-projection-side, wherein the plug-in projection (30) has two abutting surfaces (31.1) and a pressure surface (32.1),
   wherein the two abutting surfaces (31.1) are arranged spaced apart from one another,
   wherein the abutting surfaces (31.1) are arranged at least in regions in the region of the front side of the plug-in-projection-side facing the tool feed direction (v) and the pressure surface (32.1) is arranged in the region of the rear side of the plug-in projection,
   characterized in that
   the abutting surfaces (31.1) are convex.
2. Bit holder according to claim 1,
   characterized in that
   the abutting surfaces (31.1) are arranged spaced apart by means of a recess (31.2) of the plug-in projection (30).
3. Bit holder according to one of claims 1 or 2,
   characterized in that
   the abutting surfaces (31.1) have the same radius of curvature or the same curvature geometry.
4. Bit holder according to claim 3,
   characterized in that
   the radius of curvature of the abutting surfaces (31.1) is in the range between 16 mm and 32 mm.
5. Bit holder according to one of the claims 3 to 4,
   characterized in that
   the radius of curvature is a constant radius over the length of the abutting surfaces (31.1).
6. Bit holder according to one of claims 1 to 5,
   characterized in that
   the abutting surfaces (31.1) are arranged on an identical pitch circle, and/or in that the abutting surfaces (31.1) have the same center of curvature.
7. Bit holder according to one of claims 1 to 6,
   characterized in that
   the extension of the abutting surfaces (31.1) in the direction of the plug-in projection (30) is in the range between 20 mm and 50 mm.
8. Bit holder according to one of the claims 1 to 7,
   characterized in that
   the extension of the abutting surfaces (31.1) in the circumferential direction is at least 30° to 80°.
9. Bit holder according to one of claims 1 to 8,
   characterized in that
   the abutting surfaces (31.1) merge via a convex transition region into the recess (31.2), which is of concave design at least in a region.
10. Bit holder according to one of claims 1 to 9,
    characterized in that
    the abutting surfaces (31.1) are arranged symmetrically to the central transverse plane (MQ) of the plug-in projection (30), which central transverse plane (MQ) extends in the direction of the central longitudinal axis of the plug-in projection (30), and/or in that the pressure surface (32.1) is arranged symmetrically to this central transverse plane (MQ).
11. Bit holder according to one of claims 1 to 10,
    characterized in that
    the pressure surface (32.1) is arranged at a distance of at least 20 mm (distance A) from the connection region of the plug-in projection (30) to the support body (21).
12. Bit holder according to one of claims 1 to 11,
    characterized in that
    the contact surfaces (31.1) are arranged at a distance of at least 15 mm (distance dimension B) from the connection region of the plug-in attachment (30) to the support body (21).
13. Bit holder according to one of claims 1 to 12,
    characterized in that
    the center of gravity of at least one of the abutting surfaces (31.1) is not more than 20 mm (distance C) away from the center of gravity of the pressure surface (32.1) in the direction of the central longitudinal axis of the plug-in projection (30).
14. Bit holder according to any of claims 1 to 13,
    characterized in that
    the normal line through the center of gravity of the pressure surface (32.1) penetrates the plug-in projection (30) between the abutting surfaces (31.1)
15. Bit holder according to one of claims 1 to 14,
    characterized in that
    the abutting surfaces (31.1) are formed by supporting sections which are raised with respect to the plug-in projection (30).
16. Bit holder according to one of claims 1 to 15,
    characterized in that
    the normal to the pressure surface (32.1) is at an angle of between 30° and 70° to the central longitudinal axis of the plug-in projection (30).

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