EP1715106A1

EP1715106A1 - Mobile milling machine

Info

Publication number: EP1715106A1
Application number: EP05252551A
Authority: EP
Inventors: Edward Van Amelsfoort; Hans Van Sambeek
Original assignee: Caterpillar Work Tools BV
Current assignee: Caterpillar Work Tools BV
Priority date: 2005-04-23
Filing date: 2005-04-23
Publication date: 2006-10-25

Abstract

Mobile milling machines such as rotary cutters are used to mill hard and often uneven surfaces. The milling operation tends to generate high levels of shocks and vibrations that are transmitted to the host machine and operator. The machine as disclosed may be mounted on a host machine such as an excavator or the like via a hook up arrangement connected to or part of a first member of the rotary cutter. A second member is adapted to carry the cutting drums and is connected to the first member. The connection between the first member and the second member has a shock and vibration absorbing arrangement (50,162,262) reducing the level of shocks and vibrations transmitted via the host machine to the operator.

Description

Technical Field

The present disclosure relates to the field of mobile milling machines. More specifically but not exclusively the present invention relates to rotary cutters that are suitable for mounting to work machines such as hydraulic excavators or the like.

Background

Mobile milling machines such as rotary cutters have become popular tools for milling and working hard stoney surfaces such as concrete, natural stone, compacted gravel, etc. where they may be used for example to create trenches or to level uneven surfaces. The rotary cutters are often mounted to a work machine such as an excavator or the like. The excavator supplies hydraulic power which may be converted to mechanical power by a hydraulic motor for driving the cutting drums either directly or indirectly via a gear train. The cutting drum is fitted with a multitude of cutting elements ('picks') which are mounted and arranged in such a manner that vibrations and uneven loadings are minimized. However, due to the arduous circumstances and the harsh character of the work involved, the rotary cutter, the work machine and its operator are exposed to high levels of noise and vibration. This results in reduced service life of all the machinery involved and loss of operator comfort and hence productiveness. It is an object of the current disclosure to overcome one or more of the abovementioned drawbacks.

Summary of the Invention

According to the present disclosure there is provided a rotary cutter with at least one rotatably mounted cutting drum and a body having a first member and a second member. The first member is adapted for connection to a work machine. The second member has support means adapted for supporting the at least one rotatably mounted cutting drum and the support means extends into the drum from one lateral side of the drum only. Furthermore there is a shock absorbing means interposed between the first member and the second member which is adapted for reducing the transmittal of shocks and vibrations from the first member to the second member.

Brief Description of the Drawings

Fig. 1 is a diagrammatic representation of a hydraulic excavator equipped with a rotary cutter;
Fig. 2 is a partial exploded isometric representation of a first embodiment of a rotary cutter in accordance with this disclosure;
Fig. 3 is a diagrammatic representation of an elastomeric bushing provided with non-elastomeric internal and external liners;
Fig. 4 is a diagrammatic side view of a second embodiment of a rotary cutter in accordance with this disclosure;
Fig. 5 is a partial exploded diagrammatic side view of the rotary cutter from Fig. 4; and
Fig. 6 is a diagrammatic side view of a third embodiment of a rotary cutter in accordance with this disclosure.

Detailed Description

Referring now to Fig. 1, a rotary cutter 10 is mounted to a work arm 12 of an excavator 14. The operator (not shown) of the excavator 14 can position the rotary cutter 10 relative to a work surface 16 by controlling the flow of hydraulic fluid to the hydraulic rams 18 mounted to the work arm which alter the angles between the excavator body 20 and the segments of work arm 12, i.e. boom section 22, stick section 24 and tool carrier 26. Furthermore, the excavator body 20 is rotatably mounted to an undercarriage 28 to enable a rotating movement of the excavator body, the work arm 12 and the rotary cutter 10 relative to the undercarriage 28. This rotating movement allows the rotary cutter to move sideways which may facilitate the cutting process. As can be seen, the rotary cutter can be moved along any axis and in any direction within the working range of the machine. By controlling the work arm 12 not only can the rotary cutter be positioned as desired, it also allows a certain level of control over the force that is exerted by the rotary cutter 10 on the work surface 16. It is to be understood that a work machine other than an excavator may be used to perform the function of host machine or that the excavator may have a configuration different from the excavator 14 shown in Fig. 1, for example the work arm may have more or less segments.
Figs. 2 to 6 show in more detail several embodiments of a rotary cutter 10 according to the current invention. The rotary cutter 10 in the example of Fig. 2 has a body 30 with a first member 32 and a second member 34, but variants with more members may be possible. Another possible variant may have part of work arm 12 form at least partially first member 32. The first member 32 is shown as a box like structure which is preferred to give a high level of integrity. The box like structure allows for the protection of hydraulic or mechanical components as they can be mounted or routed within or through the confines of the box like structure. The box like structure may be open ended or have passages to allow entrance and exit of components such as hydraulic hoses and pipes. However, if preferred, arrangements other than a box structure can be used, for example an arrangement in the form of an 'I' beam. The first member 32 has a first end 36 and a second end 38. The first end 36 is adapted to be mounted onto the excavator 14 via an adapter such as tool carrier 26. The second end 38 is adapted for connection to the second member 34, as described in more detail below.
The second member 34 is also shown as a box like structure, but can also be constructed in a different form such as an 'I' beam. However, a box like structure may again be preferred from an integrity and component protection point of view.
Connected to second member 34 are cutting drums 40. Fig. 2 shows a rotary cutter of the dual drum type wherein the drums are mounted to opposite lateral sides of the second member 34. Both single and dual drum rotary cutters are known in the art, but the number of cutting drums is not of any particular significance to the current disclosure. Cutting drums 40 are supported from one lateral side by second member 34 in a conventional manner and are provided with a plurality of cutting tool holders 41. The cutting tools themselves are not shown. The holders 41 are arranged in a specific manner to reduce vibration, noise and harshness during operation. The cutting drums 40 may be driven directly by one or more hydraulic motors (not shown) or via alternative means such as a gear train (not shown). If driven directly by a hydraulic motor, it may be preferable that this hydraulic motor is substantially placed in a volume defined by the second member 34 or within the confines of one of the cutting drums 40 to protect the hydraulic motor and its connections.
The hydraulic motor may also be located in such a manner that it does not drive the cutting drum 40 via a direct drive shaft arrangement. It is known in the art to locate the hydraulic motor remotely from the cutting drum, wherein the driving force is transmitted from the hydraulic motor to the cutting drum 40 via a drive line such as a gear train. Similar to the first member 32, second member 34 may also be open ended or have passages to enable the entrance and exit of components such as hydraulic hoses and pipes.
In a specific embodiment of the current disclosure as shown in Fig. 2, the second member 34 is further provided with two projections 42 that are adapted to engage with the second end 38 of the first member 32. It is to be understood that the manner in which the first member 32 and the second member 34 engage may vary. For example, the first member 32 may be provided with the projections 42 instead of the second member 34 and the number and type of projections may also be varied. The second end 38 of the first member 32 is provided with at least one passage, but preferably a plurality of upper linkage passages 44. The projections 42 of the second member 34 are accordingly provided with at least one, but preferably a plurality, of lower linkage passages 46. At least one of the upper linkage passages 44 may be provided with an elastomeric bushing 50. The elastomeric bushing 50 may extend over the full length of its corresponding passage 44 or it may extend partially only. It may also be preferred to have two or more shorter bushings instead of one longer bushing.
As shown in Fig. 3 the elastomeric bushing 50 may be provided with an internal non-elastomeric liner 52 or an external non-elastomeric liner 54 or both to provide integrity and hence extended service life. Furthermore, the elastomeric bushing 50 may be an integral part of pin 48.
The first member 32 and the second member 34 may be connected to each other by pins 48 which extend through the bushings 50 in the upper linkage passages 44 and through the lower linkage passages 46. Pins 48 may be of the conventional type made out of a material such as metal and may have conventional retention means such as a bolting arrangement or retainer plate (not shown). This arrangement results in the first member 32 and the second member 34 being in substantially fixed positions relative to each other except for the movement provided by the resilience of the elastomeric bushings 50.
Another embodiment of the current disclosure is shown in Figs. 4 and 5. Like components have like reference signs as in the previous figures except for the first numeral which is embodiment specific. Whereas in the previously described embodiment the first member 32 and the second member 34 were directly connected by two or more pins 48, this embodiment has only one direct connection between the first member 132 and the second member 134. The first member 132 has an upper linkage passage 144 that corresponds to the lower linkage passages 146 (one shown only) of the second member 134. A pin 148 extends through both the first member 132 and the second member 134 to pivotally connect the first and second member. The first member 132 further has an upper linkage passage 154 whilst the second member 134 further has at least one but preferably a plurality of lower linkage passages 156.
A resilient member such as a hydraulic shock damper 162 has a first end in the form of a rod end passage 164 and second end in the form of the housing end passage 166. The shock damper 162 may be connected to the first member 132 by a pin 148 that extends through both the upper linkage passage 154 and the rod end passage 164. In a similar fashion, shock damper 162 may be connected to the second member 134 by a pin 148 that extends through the lower linkage passage 156 and the housing end passage 166.
It is to be understood that the resilient member may be of a different type than a hydraulic shock damper such as damper 162. The resilient member should be able to dampen to a certain degree shocks and vibrations that are generated by the operation of the rotary cutter. Hence the hydraulic shock damper 162 may be replaced or assisted by mechanical springs or alternatively an apparatus such as a hydraulic cylinder with a gas or spring loaded accumulator may be provided. In addition to providing a damper 162 it may be preferred to further provide any or all of the passages 144, 146, 154, 156, 164 or 166 with a bushing such as the elastomeric bushing 50. It further is to be understood that the hinge arrangement between the first member 132 and the second member 134 as enabled by the pin 148 may be replaced by any other suitable arrangement that allows this type of movement. Furthermore, the hinge and damper arrangement may be expanded by using two or more dampers arranged at opposite sides of the hinge to allow for example a larger range of travel of the second member 134. Fig. 6 shows another embodiment of the current disclosure. The basic construction principle of the rotary cutter 210 is substantially similar to previously discussed embodiments except for the connection between the first member 232 and the second member 234. The first member 232 is provided with at least two upper linkage passages 244 whilst the second member 234 has corresponding lower linkage passages 246. The rotary cutter 210 further has at least two resilient members 262 that may be similar to the resilient members 162. The connection between the resilient members 262 and the first member 232 and the second member 234 may again be substantially similar to the connection between resilient member 162 and first member 132 and second member 134. However, first member 232 and second member 234 are not pivotally connected as they are pivotally restrained by sliding mechanism 268. Sliding mechanism 268 allows second member 234 to move relative to first member 232 along an axis 270.
In addition a bushing substantially similar to an elastomeric bushing 50 may be provided in any or all of passages 244 and 246.

Industrial Applicability

During operation of a machine such as hydraulic excavator 14 with a rotary cutter 10, 110, 210 the operator controls the location of the rotary cutter 10, 110, 210 relative to the work surface 16 by controlling the flow to hydraulic rams 18 and by rotation of excavator body 20 relative to undercarriage 28. A rotation of the excavator body 20 will of course result in an arc shaped path of the rotary cutter, but this can at least partially be corrected by adjusting the angles between the individual segments of work arm 12. Note that the rotary cutter 10, 110, 210 may be applied to any surface within the range of the work machine regardless of the surface being horizontal, vertical or in an intermediary position, or of the surface being either below or above the general position of the excavator body. For this example it is assumed the work surface is uneven but substantially horizontal and in the same plane as the surface on which undercarriage 28 rests. By manipulation of the work arm 12, the rotary cutter 10, 110, 210 is forced onto the work surface.
The hydraulic system of excavator 14 may drive the cutting drums 40, 140, 240 at around a speed of 100 rpm. Each drum may have around 30 cutting tools mounted to it which for a dual drum design would result in 6000 impacts per minute. This coupled with movement of the rotary cutter 10, 110, 210 by adjustments made to the work arm 12 or the position of excavator 14 may obviously lead to high levels of shocks and vibrations. These shocks and vibrations are transferred through the loader arm 12 to the machine body 20 and the operator (not shown). By using a rotary cutter 10, 110, 210 as described in this disclosure, the shocks and vibrations may be reduced by the incorporation of the shock absorbing means such as the elastomeric members 50 or resilient members 162, 262. The shock absorbing means are interposed between a first member 32, 132, 232 and a second member 34, 134, 234 of the body 30, 130, 230 of the rotary cutter.
Depending on the type of application, the size of both the rotary cutter and the work machine and operator preference one embodiment may be preferred over an alternative embodiment. For example where vibrations are more of an issue than shocks an embodiment utilizing elastomeric members such as 50 may be preferred as the characteristics of the elastomeric members 50 may be more suited to reducing the level or intensity of vibrations rather than components such as shock absorbers 162, 262. Furthermore an elastomeric member such as 50 may also be preferred in certain applications as these elastomeric members 50 are able to function regardless of the direction of travel of the vibrations or shocks. Resilient members such as shock dampers 162, 262 may have a more limited applicability under certain conditions as they may be more adapted to absorb forces that act substantially parallel and in proximity to the axial centerline. However under different conditions, e.g. where shocks are more dominant than vibrations, shock dampers such as 162, 262 may provide better characteristics. Of course there may also be a combination of both elastomeric members such as 50 and resilient members such as hydraulic shock dampers 162, 262.
Although the preferred embodiments of this disclosure have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims.

Claims

A rotary cutter, comprising
at least one rotatably mounted cutting drum,
a body having a first member and a second member, said first member being adapted for connection to a work machine, said second member having support means adapted for supporting said at least one rotatably mounted cutting drum, said support means extending into said drum from one lateral side of the drum only,
shock absorbing means interposed between said first member and said second member adapted for reducing the transmittal of shocks and vibrations from said first member to said second member.
A rotary cutter according to claim 1, wherein said shock absorbing means comprises at least one elastomeric member.
A rotary cutter according to claim 2, wherein said elastomeric member is a bushing fitted in one of said first and second members.
A rotary cutter according to claim 3, wherein said shock absorbing means has a non-elastomeric liner provided inside said elastomeric bushing.
A rotary cutter according to any of claims 3 to 4, wherein said shock absorbing means has a non-elastomeric liner provided outside said elastomeric bushing.
A rotary cutter according to any of claims 2 to 5, wherein said first member and said second member are connected by at least one pin, said pin extending through said first member, said second member and said elastomeric bushing.
A rotary cutter according to claim 1, wherein said first member and said second member are pivotally connected.
A rotary cutter according to claim 1, wherein said first member and said second member are slideably connected.
A rotary cutter according to any of claims 7 to 8, wherein said shock absorbing means has at least one hydraulic shock damper.
A rotary cutter according to any of claims 7 to 9, wherein said shock absorbing means has at least one mechanical spring.
A rotary cutter according to any of claims 7 to 8 wherein said shock absorbing means has a hydraulic cylinder and a hydraulic accumulator.
A rotary cutter according to any of the preceding claims wherein said at least one rotatably mounted cutting drum is driven by a hydraulic motor.
A rotary cutter according to claim 12, wherein said second member defines a volume and said hydraulic motor is located substantially in said volume.
A rotary cutter according to claim 12, wherein said hydraulic motor is located substantially with the confines of said rotatably mounted cutting drum.
A rotary cutter according to claim 12, wherein the supply and return lines for said hydraulic motor are encased by said body.
A rotary cutter according to any of the preceding claims, wherein said rotary cutter has two rotatably mounted cutting drums, each of said two rotatably mounted cutting drums being mounted on opposite lateral sides of said second member.