Patent Application
20140333118
1. Field of the Invention
The invention relates to a road milling machine, in particular small milling machine, for working road surfaces, as well as to a method for mounting a cantilevered milling drum.
2. Description of the Prior Art
A quick-change system for milling drums is known from EP 1 194 651 A in which the milling drum is divided and comprises a basic drum body and a milling tube suitable for pushing onto the basic drum body. As only the milling tube needs to be replaced, handling for the replacement of a milling drum is facilitated so that the time and amount of work required for the replacement are minimized. However, said quick-change system essentially relates to large milling machines with a milling drum diameter of approx. 1 m and a milling width ranging between 1.50 m and 4.40 m.
In small milling machines, on the other hand, the milling drum is of an integral design. The length of a milling drum for a small milling machine is typically smaller than its diameter. For example, milling drums for small milling machines have a diameter ranging from 460 mm to 750 mm at a width of between 250 mm and 600 mm.
A further difference between the milling drums of a small milling machine and a large milling machine is that, on the outer circumference of milling drums for small milling machines, toolholders are welded directly onto the drum whereas, with milling drums for large milling machines, quick-change toolholders are used in which a basic part is welded onto the drum which accommodates a toolholder in a replaceable fashion.
Such a small milling machine is known, for example, under the designation Wirtgen W 50 DC. The basic design of a generic road milling machine is known from DE 103 47 873 A1.
The small milling machine comprises a milling drum that is supported at the machine frame in a drum casing and can be driven by a milling drum drive.
The known milling drum drive comprises a drum gearbox which, at its free end, comprises a connecting flange with axially projecting stud bolts for mounting the milling drum. The stud bolts engage with a connecting flange of the milling drum in drill holes arranged accordingly so that the milling drum can be fastened at the drum gearbox by means of nuts. Furthermore, the drum gearbox may comprise a centering spigot which interacts with a corresponding central opening in the connecting flange of the cantilevered milling drum.
The milling drums used for small milling machines usually have a high weight of, for example, up to 300 kg. They are therefore too heavy to allow manual mounting. Handling an integrally designed milling drum for small milling machines is additionally made more difficult due to the fact that the connecting flange is not arranged in the centre of the milling drum axially as approx. two thirds of the interior space of the milling drum is taken up by the milling drum drive. In view of this, the connecting flange of a milling drum for small milling machines is usually located in the vicinity of the front end of the milling drum opposite the drive. Due to the resulting eccentric position of the centre of gravity relative to the connecting flange, the milling drum tilts over the connecting flange during handling. There is also the fact that, when replacing the milling drum under practical conditions, the ground is frequently uneven so that replacing the milling drum is made significantly more difficult. The tools positioned on the milling drum create an irregular three-dimensional surface structure of the milling drum, which results in said milling drum assuming a not clearly definable tilted position on a transport device, such as a forklift truck. Once the milling drum with its heavy weight rests on the lifting device, it can no longer be turned on said lifting device. In view of this, mounting a milling drum at the drum gearbox is extremely difficult even with the aid of a lifting device, in which process the projecting stud bolts of the drum gearbox can easily be damaged and must then be replaced with additional mounting effort.
It is therefore the object of the present invention to simplify the replacement of a milling drum and to facilitate mounting and removal of a new milling drum while simultaneously reducing the repair effort.
The above object is achieved, according to the invention, in that the milling drum drive comprises, as a minimum, one mounting stud which engages with a corresponding opening adapted to said mounting stud in the connecting flange of the milling drum, wherein the mounting stud projects axially vis-à-vis the stud bolts to such an extent that the milling drum rests on the mounting stud prior to engaging with the stud bolts.
The invention advantageously provides that, during the mounting procedure, the milling drum, after having been aligned to the milling drum drive, can first be pushed onto the mounting stud projecting vis-à-vis the stud bolts so that an alignment of the cut-outs, for example, drill holes in the connecting flange, to the stud bolts is initially not of the essence and the milling drum can be supported on the mounting stud. The milling drum can then easily be turned on the mounting stud until the drill holes are in alignment with the stud bolts, in which arrangement the milling drum can then be pushed on further until, in the end, the milling drum has been fully pushed onto the stud bolts and a possible centering spigot of the drum gearbox engages with a complementary central opening in the connecting flange of the milling drum. Thereafter, the milling drum can be permanently fastened using the usual fastening means.
The at least one mounting stud is preferably of replaceable design. This enables the mounting stud to be replaced in the event of the same being damaged, or the mounting of mounting studs of different shape or diameter, and it additionally permits the alternative to not mount the mounting stud if milling drums of an older design are to be mounted that are not compatible with a mounting stud. A further alternative provides for the mounting stud to be used for the purpose of mounting only and removed for the operation of the road milling machine as the mounting stud cannot remain there, for example, due to a lack of installation space.
A single mounting stud is preferably intended coaxially to the milling drum drive and to the milling drum. The central arrangement of a single mounting stud enables particularly simple and safe mounting of the milling drum.
The milling drum is preferably of integral design and comprises a single, axially eccentrically arranged connecting flange. The milling drum is comprised of a drum carrying the tools and of a single connecting flange for connection to the milling drum drive, which results in a cantilevered support of the milling drum. As the milling drum drive protrudes into the milling drum, the connecting flange of the milling drum is arranged eccentrically in axial direction, that is, in the area of the last third of the milling drum.
The stud bolts projecting from the milling drum drive are arranged on a hole circle, with the mounting stud being arranged concentrically to the stud bolts and radially inside relative to the same.
The mounting stud may taper towards the outside. Pushing on the milling drum with its central opening is thus facilitated as a less accurate positioning of the milling drum is sufficient in order to enable pushing the same onto the mounting stud.
The central opening of the connecting flange may alternatively or additionally widen towards the milling drum drive.
A preferred embodiment intends for the outer front end of the milling drum to end nearly flush with the lateral outer side of the machine frame, the so-called zero-clearance side, in order to enable milling as close along any obstacles as possible. In this arrangement, the machine frame is preferably supported by a chassis comprising a front axle and a rear axle with wheels, with the milling drum being arranged between the rear wheels. This arrangement concerns the normal operation of the road milling machine in which both rear wheels are arranged coaxially and preferably in a vertical plane with the milling drum axis. For the close-to-edge operation, a pivoting rear wheel may be provided on the zero-clearance side which can be pivoted into a position in front of the milling drum and inwards relative to the zero-clearance side. Such an arrangement is known, for example, from DE 196 31 042 A1.
The road milling machine is preferably a rear-loading milling machine in which a transport device for the milled material worked off by the milling drum discharging towards the rear is arranged behind the milling drum as seen in the direction of travel.
A cover cap may be attached at the mounting stud. Said cover cap protects the ends of the stud bolts and the fastening means interacting with the stud bolts, such as nuts, and prevents the fastening means from being contaminated or damaged during the milling operation.
The central opening in the connecting flange of the milling drum may comprise an inner supporting surface resting on the mounting stud, said supporting surface not fully enclosing the mounting stud. The multiply interrupted supporting surface facilitates pushing of the milling drum onto the mounting stud and reduces the effects of changes in temperature while a sufficient supporting surface is ensured at the same time.
The mounting stud is preferably arranged coaxially to a centering spigot, in which arrangement the mounting stud may additionally feature, at least on the side facing the centering spigot, essentially the same outer diameter as the centering spigot. It is understood that, in the event of a mounting stud, a centering device may be present but is not mandatory.
The mounting stud may be chamfered at its free end in order to facilitate pushing on of the milling drum.
In a method for mounting a cantilevered milling drum in a road milling machine, in particular small milling machine, for working road surfaces, in which the milling drum is driven by a milling drum drive, where stud bolts for mounting the milling drum project from the milling drum drive, said stud bolts engaging with cut-outs or drill holes arranged accordingly in a connecting flange of the milling drum, the following steps are advantageously intended:
In the following, one embodiment of the invention is explained in greater detail with reference to the drawings.
The following is shown:
The automotive road milling machine 1 for working ground surfaces depicted in
Furthermore, the connecting flange 14 features a central opening 28 which is adapted to the diameter of the mounting stud 20. The central opening 28 may be of circular design or may, for example, exhibit the contour inferable from
In the position depicted in
As can be inferred from
It is understood, however, that the mounting stud 20 can fully assume the function of the centering spigot 40 so that an additional centering spigot 40 is not required.
It is further understood that the mounting stud 20 must not necessarily feature a circular cross-sectional contour but may, for example, also be of a star-shaped or triangular-shaped cross-sectional design.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102013208638.5 | May 2013 | DE | national |
