Patent Publication Number: US-8118369-B2

Title: Milling drum for a construction machine, construction machine as well as gearbox unit for a milling drum

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a milling drum and a construction machine, as well as a gearbox unit for a milling drum. 
     It is often necessary, due to varying job site situations and milling operations, to adapt the milling tool of a road milling machine to the specific tasks at hand. A milling drum with a particular spacing of the cutting tools or a different tooling is required when, for instance, a specific surface texture is to be achieved. In another application, only specific carriageway widths are to be removed, which requires a milling drum with a particular working width. 
     As a rule, a special milling machine has to be employed in these situations, or else the machine must be equipped with a milling drum adapted to the task at hand. Exchanging the milling drums presently involves a lot of effort, however, and requires special aids for the assembly or disassembly of the milling drum. 
     Milling drums for road milling machines or recyclers are known from EP 1194651 B and EP 1520076 B where the milling drum displays an interchangeable milling tube with the axis of the said milling tube being supported, by means of a support ring, on a support ring mount of a rotating body coupled to a milling drum drive. The support ring sits on the support ring mount with a predetermined play where dirty water, dust and fine particles of the road surface can penetrate the gap between the support ring and the support ring mount, in particular due to relative movements between the support ring and the support ring mount resulting from the milling operation. The capillary attraction of the clearance fit intensifies this effect, so that dirty water and fine-grained particles penetrate the fit. 
     When the milling tube with the support ring is to be pulled from the support ring mount for the purpose of disassembly, this is often very difficult or not possible at all. 
     Disassembly is not easy in view of the given dimensions, namely with a support ring that is short in relation to the diameter of the milling drum when seen in axial direction, even though the assembly in a cleaned state can also prove to be difficult due to tilting. 
     Supporting surfaces of conical design have also turned out not to be practicable as they can, on the one hand, settle too strongly and, on the other hand, display excessive radial play when the milling drum to be pushed on is too short. A conically designed supporting surface would, therefore, require the conical support ring and support ring mount to be positioned within an accuracy range of +/−1 mm in order to enable a function at all, in which case the problem of a conical connection being prone to seizing will persist nevertheless. 
     The purpose of the invention is, therefore, to simplify the assembly and disassembly of the milling tube in milling drums with interchangeable milling tubes, in construction machines with milling drums and in gearbox units driving a milling drum. 
     The characteristics of this application serve to provide a solution to this purpose. 
     SUMMARY OF THE INVENTION 
     The invention provides in an advantageous manner that the support ring and the support ring mount of the rotating body display several complementary supporting surfaces arranged concentrically to the axis of the milling drum, where the said supporting surfaces have different supporting circle diameters and are arranged behind one another axially with their diameters decreasing incrementally in the pulling direction. 
     Due to the staircase-shaped design of the supporting surfaces of the support ring and the support ring mount, the milling tube has to be pulled off in an amount corresponding to the width of one step only to disengage the support ring with the support ring mount, this being achieved without reducing the overall area of the supporting surface. With a fivefold step, for instance, the distance required to separate the supporting surfaces from one another can be reduced to one fifth of the total axial length of the supporting surface. 
     It is of particular advantage here that the effective supporting surface for the milling tube remains practically the same. 
     In one preferred embodiment, a minimum number of three, preferably five supporting surfaces are arranged behind one another axially. 
     The supporting surfaces arranged behind one another axially have a length of 5 to 40 mm, preferably 10 to 20 mm. This creates a stable supporting surface for a milling tube of a milling drum. 
     The length of a supporting surface may be equal in axial direction. This offers the advantage that, when pulling, all supporting surfaces are disengaged simultaneously. 
     Alternatively, the supporting surfaces may also have different lengths in axial direction, and preferably in such a manner that the length of the supporting surfaces decreases in accordance with the decreasing supporting circle diameter. This offers the advantage, in particular during assembly, that not all of the supporting surfaces are engaged simultaneously, which may facilitate assembly. 
     Another preferred embodiment provides that the supporting surfaces of the support ring are offset axially in relation to the supporting surfaces of the support ring mount when seen in the pulling direction of the milling tube, in such a manner that annular chambers are formed at the junctions of the individual steps. 
     The annular chambers may be used in an advantageous manner to be filled with an anti-corrosive agent or a lubricant. 
     For this purpose, the annular chambers may be connected with an injection duct that is suitable for the purpose of injecting an anti-corrosive agent and/or lubricant. The injection duct may, for instance, display a nipple for injecting grease. 
     The supporting surfaces may be coated with a gliding layer to facilitate assembly and disassembly. 
     The support ring mount may comprise a single-part ring or may also be integral with the rotating body. The single-part support ring mount may, for instance, be pushed onto the rotating body and secured there axially. 
     Alternatively, the support ring mount may be integral with the rotating body whereby the number of components can be reduced. 
     An alternative embodiment provides that the support ring mount comprises a multi-part, preferably two-part ring that is suitable for being mounted on the rotating body. Such support ring mount is advantageous when a support ring mount is not capable of being pushed onto the rotating body. 
     The support ring mount is mounted on the rotating body in an immovable manner axially, forming a floating bearing. The support ring mount can be secured to the rotating body at different positions axially. 
     An advantageous continuation of the invention provides that the rotating body is a basic drum body for supporting the milling tube and/or an output housing of a gearbox unit of the milling drum drive. 
     When mounted on two sides, the axis of the milling tube can, on the one hand, be mounted in a removable side wall and, on the other hand, rest upon the support ring mount of the rotating body by means of the support ring, wherein the milling tube can be pulled from the support ring mount of the rotating body in the pulling direction after the side wall has been removed. 
     An advantageous continuation provides that the basic drum body is coupled with the milling drum drive and supports the end of the milling tube facing the side wall. 
     A further advantageous continuation of the invention provides that a push-off device engages with the milling tube or with the rotating body, which permits the milling tube to be pulled from its mounted position in the pulling direction for the purpose of disassembly. The push-off device may be provided either mechanically or hydraulically. 
     Furthermore, it is provided in a particularly advantageous manner that the supporting surfaces with different supporting circle diameters, arranged behind one another axially, show a chamfer of, for instance, less than 45° at the junctions of the individual steps. This chamfer allows the milling tube to be centred more easily during assembly, thus facilitating the assembly. Preferably, a chamfer of less than 45° is used. 
     In the following, embodiments of the invention are explained in more detail with reference to the drawings. The following is shown: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  a road construction machine. 
         FIG. 2  a milling drum mounted on both sides. 
         FIG. 3  the supporting surfaces of the support ring and the support ring mount, lying on top of each other, in accordance with detail III in  FIG. 2 . 
         FIG. 4  an alternative embodiment of a support ring mount with grease lubrication. 
         FIG. 5  a two-part support ring mount. 
         FIG. 6  a section along the line VI-VI in  FIG. 5 . 
         FIG. 7  a half-section of the support ring in the direction of the arrows VII in  FIG. 5 . 
         FIG. 8  a push-off device in accordance with the enlarged detail VIII in  FIG. 2 . 
         FIG. 9  a further embodiment for mounting a milling tube. 
         FIG. 10  an embodiment for a one-sided mounting or floating mounting respectively of the milling tube. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  depicts a road construction machine  1  in which a quick-change system for milling tubes can be used. 
     The road construction machine is a road milling machine which commonly has a machine frame, with a combustion engine and operator&#39;s platform being mounted on said machine frame. The automotive road construction machine has height-adjustable lifting columns attached to the machine frame, with support wheels or crawler track units being mounted at the said lifting columns. 
     The milling drum  2  is located below the machine frame in a drum housing  9  that displays the side walls  13 ,  15  at the sides. The reference mark  7  indicates the cutting outline of the tools located on the milling drum  2 . The material processed by the milling drum  2  is discharged on a first loading conveyor or is transported further onto a second, height-adjustable and slewable loading conveyor in a basically known manner. 
     In  FIG. 2 , a milling drum  2  is mounted in a rotatable manner between side walls  13 ,  15  of the drum housing  9 , where the said side walls  13 ,  15  are arranged orthogonal to the axis  20  of the milling drum  2 , and where the said milling drum  2  is driven via a driving device  16 , mounted at the side wall  13  on the drive side, and a gearbox unit  17 . The milling drum  2  depicted in  FIG. 2  comprises an integral milling tube  4 , which is attached to a basic drum body  19  in an interchangeable manner. The basic drum body  19  is in turn attached to the output housing  21  of the gearbox unit  17 . The basic drum body  19  is arranged axially at the side of the output housing  21 , transferring the torque of the gearbox unit  17  to the particular milling tube  4  inserted in the manner of a reduction gear. 
     The milling drum drive  16  preferably comprises a belt drive. 
     In  FIG. 2 , the milling tube  4  is bolted to the basic drum body  19  by way of an annular flange  23  which is in turn mounted in the removable side wall  15  in a rotatable manner. A support ring  8  is arranged on the side of the milling tube  4  facing the milling drum drive  16 , where the said support ring  8  is connected to the milling tube  4  in a non-rotatable manner and co-operates with a support ring mount  12  sitting on top of the output housing  21 . 
     The support ring  8  and the support ring mount  12  display several complementary supporting surfaces  22 ,  24  arranged concentrically to the axis  20  of the milling drum, where the said supporting surfaces  22 ,  24  have different supporting circle diameters and are arranged behind one another axially with their diameter decreasing incrementally in the direction of the side wall  15 . In the embodiments, five supporting surfaces, for instance, are arranged behind one another axially. In the embodiments presented, the axial length of the supporting surfaces  22 ,  24  is 15 mm. It can vary, however, depending upon the diameter of the milling drum  2 , between 5 and 40 mm and preferably between 10 and 20 mm. 
     The embodiments show that all supporting surfaces  22 ,  24  are of the same length axially. They may, however, also have different lengths, and preferably in such a manner that the length of the supporting surfaces  22 ,  24  decreases in accordance with the decreasing supporting circle diameter. 
     As can best be seen from  FIGS. 3 and 4 , the supporting surfaces  22  of the support ring  8  are offset axially in relation to the supporting surfaces  24  of the support ring mount  12  when seen in the direction of the side wall  15 , and in such a manner that annular chambers  25  are formed at the junctions of the individual steps. The annular chambers  25  may be filled with an anti-corrosive agent and/or a lubricant. As can be seen from  FIG. 4 , an injection duct  26  may be provided where, as can be seen from  FIG. 3 , the said injection duct  26  may be used to supply at least three annular chambers  25  with, for instance, grease via a grease nipple  28 . 
     The supporting surfaces  22 ,  24  may be coated with a gliding layer to facilitate the assembly and disassembly of the milling tube  4 . 
     The support ring mount  12  may comprise a single-part ring, as can be seen from  FIG. 2 , or else may be integral with the output housing  21  of the gearbox unit  17 , as is shown in the embodiments of  FIGS. 9 and 10 . 
     As can be seen from  FIGS. 5 and 6 , the support ring mount  12  may alternatively comprise a multi-part, in  FIGS. 5 and 6  two-part, ring that is suitable for being mounted on a rotating body, such as, for instance, the output housing  21  of the gearbox unit  17 . 
     The support ring mount  12  may also be mounted on a rotating body in a movable manner axially, as is possible in the embodiments in  FIGS. 2 to 4 , or may be mounted on the rotating body in an immovable manner axially, as can be seen from the embodiments in  FIGS. 9 and 10 . 
     Mounting bolts  14  can be seen in  FIG. 5 , by means of which the support ring mount  12  can be mounted on a rotating body. It is understood that the rotating body may also comprise an annular flange or connecting flange and need not necessarily be an output housing  21  or a basic drum body  19 . 
       FIG. 6  is a section along the line VI-VI in  FIG. 5 , wherein the section runs through the injection duct  26 . 
       FIG. 7  shows a side view of the support ring mount  12  along the line VII-VII in  FIG. 5 . 
     A mechanical push-off device  29  is shown in  FIG. 7 , which allows the milling tube  4  to be pulled from its mounted position on the support ring mount  12  by means of bolts  30 . 
     To do this, the bolts  30  are screwed against the mounting flange  23 , which allows the milling tube  4  of the milling drum  2  to be pulled. 
     It can also be seen from  FIG. 7  that one chamfer  32  each of less than 45° is provided between the supporting surfaces  24  of the support ring mount  12  at the junctions of the individual steps, which facilitates assembling and centering of the milling tube  4 . Corresponding chamfers  32  are also provided between the supporting surfaces  22  of the support ring  8 . 
     The supporting surfaces  22 ,  24  are arranged concentrically, preferably coaxially, to the axis  20  of the milling drum. One step between the supporting surfaces  22 ,  24  has a height of, for instance, 1 to 4 mm, with an increment between steps of 2 mm having turned out to be of particular advantage.