Milling drum having a milling drum rotor

The present application claims priority to German Patent Application Ser. No. DE 10 2024 113 050.4 filed May 8, 2024, which is incorporated herein by reference.

The disclosure relates to a milling drum having a milling drum rotor, for a ground milling machine, wherein bottom parts of tool systems are attached to the surface of the milling drum rotor in a projecting manner, wherein at least a subset of the bottom parts are disposed spaced apart from one another in the circumferential direction of the milling drum rotor, wherein filling elements are disposed in the spacer area between some of the bottom parts spaced apart in the circumferential direction, which filling elements are each welded to the bottom part disposed in front of and behind the filling element in the circumferential direction of the drum, respectively, and to the surface of the milling drum rotor.

Milling drums according to the disclosure are used in ground working machines to remove the ground to be worked. Road milling machines are used, for instance, to mill the surface of a roadway. To this end, the milling drum is guided across the road surface. Tool systems projecting radially outwards are attached to the milling drum. These tool systems can, for instance, have a bottom part and a toolholder interchangeably mounted thereon. The toolholder can hold a replaceable or non-replaceable pick. The pick, for instance a round pick, can be used to machine and remove the road surface. Such milling drums are described, for instance, in EP 2 411 581 B1 or EP 3 162 959 B1 (U.S. Pat. No. 10,167,721).

On milling drums according to the disclosure, the tool systems can be at least partially attached and arranged in such a way that they form part of a clearing and conveyor screw. For this purpose, the tool systems are arranged in a helical pattern one behind the other on the surface of the milling drum rotor. Preferably, several clearing and conveyor screws may be formed on the surface of the milling drum rotor. The removed ground material is conveyed in the lane areas between the clearing and conveyor screw(s), for instance towards the axial center of the milling drum rotor. Ejectors may be arranged in this area. The ejectors are used to eject the ground material from the working area of the milling drum, for instance onto a conveyor belt.

For the purposes of this document, “radial(ly)” refers to the axis of rotation of the milling drum. “Radial(ly)” does not necessarily mean that that there necessarily has to be an arrangement of a component that is oriented exactly perpendicular to the axis of rotation of the milling drum. Rather, this is to also describe an essentially perpendicular orientation.

For the purposes of this document, “axial(ly)” refers to the axis of rotation of the milling drum. “Axial(ly)” does not necessarily mean that there necessarily has to be an arrangement of a component that is oriented exactly axially to the axis of rotation of the milling drum. Rather, this is to also describe an essentially axial orientation.

For the purposes of this document, “in the circumferential direction/circumferentially” refers to the axis of rotation of the milling drum. “In the circumferential direction/circumferentially” does not mean that there necessarily has to be an arrangement of a component that is oriented exactly in the direction of rotation of the milling drum. Rather, this is to also describe an arrangement that is essentially in the direction of rotation.

JP H 083919 A discloses a milling drum having helical ribs on its surface. Interchangeable toolholder systems, namely a combination consisting of a toolholder and a pick, can be mounted on these ribs.

Similar to JP H 083919 A, DE 37 08 520 C1 describes a milling drum on the surface of which a comb in the form of a helical spiral is applied to form a transport screw. Toolholders can be attached to the comb. DE 37 08 520 C1 also describes a design variant, in which a metal plate is screwed onto the milling drum between the toolholders. The metal plates projecting radially beyond the surface of the milling drum bridge the gap between adjacent toolholders to support the conveying action.

In systems which are also known from the state of the art, the spacing between two toolholders is bridged by means of a cuboid filling element to form the clearing and conveyor screw. This filling element is welded to the surface of the milling drum rotor and the two adjoining toolholders. High-performance milling machines are sometimes subjected to extremely high loads, which can result in damage to the filling element.

Therefore the disclosure addresses the problem of providing a milling drum of the type mentioned at the beginning, in which the load-bearing capacity of the tool systems and the filling elements on the milling drum is improved.

This problem is solved in that at least a subset of the filling elements has a base body, to which at least one protrusion projecting radially outwards in relation to the axis of rotation of the milling drum is integrally formed, and in that the protrusion is welded to the rear end of the front bottom part in the circumferential direction or to the front end of the rear bottom part in the feed direction.

The inventors have recognized that the connection between the filling element and the adjacent toolholder is subjected to a high load during the machining operation. The connection is formed by a welding material. This welding material is relatively brittle and not very ductile. If extremely high loads are now applied to the tool systems, these are transferred to the bottom parts. In so doing, the bottom parts are elastically deformed, which in extreme cases can result in damage to the weld seam.

As a countermeasure, the disclosure provides a protrusion that projects beyond the base body of the filling element. The protrusion is welded to the adjacent bottom part. The protrusion introduces elasticity into the filling element, as the latter can deform elastically in relation to the base body. In extreme load situations, the weld seam that connects the protrusion to the bottom part is not excessively stressed, but the material stresses are relieved via the protrusion into the base body. This prevents the welded joint formed between the bottom part and the filling element from breaking. Overall, a milling drum according to the disclosure is therefore characterized by a higher load-bearing capacity, which results in an increase in the performance of the milling drum.

According to a preferred variant of the disclosure, provision may be made for a front and a rear protrusion to be formed on the base body, which protrusions are arranged spaced apart from each other in the circumferential direction, and for the front protrusion in the circumferential direction to be welded to the front bottom part and for the rear protrusion to be welded to the rear bottom part. The fact that both bottom parts connected to the filling element are each connected to a protrusion further improves the load-bearing capacity. In particular, every protrusion can be individually adapted to the load case of the adjacent front or rear bottom part. It has been shown that significantly different stress ratios occur in the connection area of the front protrusion to the front bottom part and in the connection area of the rear protrusion to the rear bottom part.

To avoid damaging stress peaks on the molded part, provision may be made in such a design for the base body to be delimited radially on the outside by an end face, for the front protrusion arranged at the front (in the circumferential direction) of the base body to have a rear transfer section, and for the rear transfer section and the end face to be transferred into each other via a rounding transition, and/or for the rear protrusion arranged at the rear (in the circumferential direction) of the base body to have a front transfer section and for the front transfer section and the end face to be transferred into each other via a rounding transition. Preferably, the rounding transition(s) can also be designed such that they increase the cross-section of the protrusion in the connection area of the protrusion to the base body. This increases the section modulus against bending.

If provision is made for the rear transfer section and the end face and/or the front transfer section and the end face to be tangentially transferred into each other, then discontinuity jumps, which can result in notch stresses, are avoided in the transition area between the base body and the protrusion.

A possible variant of the disclosure can be such that the end face is convex and/or concave in at least a subsection. The cross-section of the base body and thus its bending and tensile strength can be influenced in a targeted manner by such a curvature. A concave curvature results in a weakening of the cross-section. A convex curvature results in an enlargement of the cross-section. The fact that curvatures are used instead of discontinuities means that continuous cross-sectional transitions are formed, which improve the load-bearing capacity.

A further preferred variant of the disclosure can be such that the front and/or the rear protrusion has/have a radially outer head area, which is coupled to the base body via a foot area, and that the protrusion in the foot area has a lower section modulus against bending about an axis parallel to the axis of rotation of the milling drum than the part of the head area of the front and/or the rear protrusion adjoining the foot area.

A variant of the disclosure may be characterized in that the front protrusion has a front longitudinal edge at its radially outer end area, wherein the front longitudinal edge extends in the direction of the axis of rotation of the milling drum, and in that the front longitudinal edge is connected to the front bottom part by means of a weld seam. Additionally or alternatively, provision may also be made for the rear protrusion to have a rear longitudinal edge at its radially outer end area, wherein the rear longitudinal edge extends in the direction of the axis of rotation of the milling drum and for the rear longitudinal edge to be connected to the rear bottom part by means of a weld seam. The front and rear longitudinal edges are positioned far away from the surface of the milling drum. This improves the support of the filling element in relation to the neighboring bottom part. The welded connection in the area of the longitudinal edges allows the bending forces to be transferred more effectively.

A particularly preferred variant of the disclosure is such that the front protrusion has front transverse edges on its opposite ends, which are disposed spaced apart from each other in the direction of the axis of rotation of the milling drum, and that the front transverse edges are welded to the front bottom part and/or that the rear protrusion has rear transverse edges on its opposite ends, which are disposed spaced apart from each other in the direction of the axis of rotation of the milling drum, and that the rear transverse edges are welded to the rear bottom part. The inventors have recognized that a triaxial state of stress occurs during machining, in which torsional stresses in particular also occur in the transition area between the bottom part and the filling element. To take this into account, the protrusion according to the disclosure is welded to the adjacent bottom part on its opposite ends in the area of the front and rear transverse edges. This significantly increases the torsional strength of the connection.

In so doing, preferably provision may be made for the spacing between the front and/or rear transverse edges in the direction of the axis of rotation of the milling drum and in the connection area of the filling element to the surface of the milling drum to be at least 0.4 times to 1.0 times the width of the assigned bottom part in this direction and in the connection area of the bottom part to the surface of the milling drum. Such a design is particularly suitable for the use of the milling drum in road milling machines. The milling drum is particularly easy to manufacture if, in this case, the spacing between the front and/or rear transverse edges is essentially equal (preferably with a deviation of no more than 10%) to the width of the assigned bottom part in the connection area of the bottom part to the surface of the milling drum.

Preferably, the spacing between the front and rear transverse edges is identical in the direction of the rotation axis of the milling drum. In that case, the filling element can be easily produced as a forged part. It is also conceivable that the filling element can be manufactured in a simple way as a punched part from a sheet metal blank or as a flame-cut part from a sheet metal blank.

The spacing between the front and/or rear transverse edges in the direction of the axis of rotation of the milling drum is preferably at least 30 mm and at most 80 mm. A design in which the spacing between the front and/or rear transverse edges is a minimum of 55 mm and at most 60 mm has proven to be particularly durable.

Additionally or alternatively, provision may be made for the length of the filling element to be at least 40 mm and at most 140 mm. Preferably, provision may be made for the length of the filling element to be at least 55 mm and at most 75 mm.

The length of the filling element is defined as the extension of the filling element in the circumferential direction of the milling drum.

According to a preferred variant of the disclosure, provision may be made for at least one of the protrusions to be delimited by a cover section on its end facing away from the milling drum, and for the extension of the cover section in the circumferential direction of the milling drum to be at least 15 mm. In this way, a sufficient width of the weld seam can be achieved in the area of the cover section for the purpose of a stable connection of the protrusion to the adjoining bottom part in the area of the cover section.

Preferably, the weld seam can extend across the entire length of the cover section extending in the circumferential direction of the milling drum. This results in a stress-optimized transition between the protrusion and the adjoining bottom part.

A particularly preferred variant of the disclosure can be such that the ratio of the length of the filling element in the circumferential direction of the milling drum, preferably in the connection area of the filling element to the surface of the milling drum, in relation to the length of the bottom part in the circumferential direction of the milling drum, preferably in the connection area of the bottom part to the surface of the milling drum, is selected to be in the range from 0.4 to 1.4, preferably in the range from 0.55 to 0.75.

Within the scope of the disclosure, provision may also be made for the cantilever of the front protrusion beyond the base part in the radial direction to be greater than the cantilever of the rear protrusion beyond the base part in the radial direction. This results in a load-optimized design.

If provision is made for the front and/or rear longitudinal edge to be disposed radially set back relative to the radially outer end of the protrusion to form a chamfer extending in the direction of rotation in the form of a weld seam preparation, then the production of a heavy-duty weld seam is simplified.

shows a partial perspective view of a milling drumfor a road milling machine. As the illustration shows, the milling drumhas a milling drum rotor. Tool systems are attached to the surfaceof the milling drum rotor. Surfacemay be referred to as a rotor outer surface. The tool systems can preferably have at least a bottom partand a toolholder. Preferably, the toolholderis detachably attached to the bottom part.

The bottom partsare arranged helically relative to one another on the surfacein the circumferential direction, to form a cutting and clearing helix. Welded joints are used to attach the bottom partsto the surface.

Advantageously, at least one ejectoris disposed in the area of the center of the milling drum rotor. The cutting and clearing helices are helically rotated around the circumference of the surfacetowards the ejectors. The cutting and clearing helix transports material removed by the toolholdersto the ejectorsduring machining operation. The ejectorsconvey the fed material out of the working area of the milling drum, for instance onto a conveyor belt (not shown).

Filling elementscan be used to at least partially fill the spacing areas between the individual tool systems. For better clarity,shows three tool systems that are connected in series by filling elements.

Of course, several or all tool systems on the milling drumcan also be connected by filling elements.

In this exemplary embodiment, the milling drumis equipped with so-called angle rings at its longitudinal ends. A large number of tool systems are arranged in a row here. The other tool systems attached to the milling drumor at least a large part of these tool systems, in particular those forming a clearing and conveyor screw, are preferably disposed spaced apart from one another and connected to filling elements.

The design and arrangement of the filling elementswill be discussed in more detail later.

show a tool system having a bottom partand a toolholderattached thereto.

The bottom parthas a connection end, which can have a, preferably concave, curved connection surface. By means of this connection end, the bottom partcan be placed on the convex surfaceof the milling drum rotorshown inand the bottom partcan be suitably attached thereto, for instance by means of a welded connection.

Provision may be made for the bottom partto have lateral clearancesin the transition area to the connection end. These clearancescan be used to hold welding material to form a tack weld.

The base bodyof the bottom partforms the bottom connection end. This base bodyhas an anterior front end.in the feed direction V and a posterior rear end.in the feed direction V. The bottom partis delimited by lateral surfaces at the sides. The feed direction V extends from left to right in. This feed direction V results from the intended use of the toolholderor the tool system.

Provision may be made for at least one shoulder.to be present in the area of at least one of the lateral surfaces to form a material diverting area.

shows that the bottom partcan have a holder mount. The holder mounthas front support surfaces.,., which are disposed at least sectionally in front of a plug-in mount. The plug-in mountcan be inserted as a penetration or as a depression in the base bodyof the bottom part.

Preferably, an offset.is disposed between the two front support surfaces.,.in the area in front of the plug-in mount. The two front support surfaces.,.are arranged at an angle to each other, as can be seen in particular in. This angle opens towards the top of the bottom part.

The bottom partmay also have at least one rear support surface.,.in its area facing the rear end.. In this exemplary embodiment, two rear support surfaces.,.are used. The rear support surfaces.,.are aligned with each other such that they are disposed on one plane. However, it is also conceivable that the two rear support surfaces.,.are at an angle to each other, wherein they preferably form an obtuse angle.

The two rear support surfaces.,.are each formed by support sections.. To this end, the support sections.may form parts of a protrusion.. Preferably, the two protrusions., which each form a support section., are arranged spaced apart from each other and transverse to the feed direction V.

illustrates that the two rear support surfaces.,.can also be interconnected by a transition section.. The transition section.may then also be used to create a support for the toolholder.

As shown in, one front support surface.,.each merges into respective rear support surfaces.,.on both ends of the bottom part. Advantageously, there are offsetsbetween the front support surfaces.,.and the assigned rear support surfaces.,., which offsets can be groove-like. The front support surfaces.,.are thus spatially separated from the rear support surfaces.,.to form defined support areas.

shows that the plug-in mountcan be equipped with an insertion extension.at its upper end. This insertion extension.is used to facilitate the insertion of a plug-in attachmentof the toolholder(see).