Mining or in situ disintegration of hard material – Cutter tooth or tooth head – Tooth mounted on helical head portion or head with helical...
Reexamination Certificate
2000-05-18
2004-08-24
Shackelford, Heather (Department: 3673)
Mining or in situ disintegration of hard material
Cutter tooth or tooth head
Tooth mounted on helical head portion or head with helical...
C299S102000, C299S104000, C299S106000, C299S110000
Reexamination Certificate
active
06779850
ABSTRACT:
The present invention relates to a cutting apparatus for use in a cutting machine, and to a block for use in a cutting apparatus.
Cutting machines are used in a variety of applications including mining, digging and earth working operations. One application of a cutting machine in the removal of asphalt surfaces from roads. The cutting apparatus of a cutting machine is coupled to a drive mechanism which drives or otherwise rotates the cutting apparatus.
A known cutting apparatus of the prior art includes a cutting drum which is commonly, although by no means exclusively, generally cylindrical in shape. The cutting apparatus has disposed about its surface a number of cutting assemblies comprising a cutting tool mounted in a holder. The cutting tool assemblies are welded, bolted or otherwise attached to the radially outer surface of mounting blocks which extend from the cutting drum. These bulky mounting block and cutting tool assemblies are staggered about the surface of the drum.
When operating the cutting machine, the projecting portions of the cutting apparatus including the cutting tool assemblies hit various parts of the material being removed or excavated. In the particular application of a cutting machine used to remove a road surface, there are hidden obstructions under the surface of the road that are hit by the cutting machine including sewer drains, manhole pits, stormwater covers, steel bars including train and tram tracks, and water mains shut-off valves. When various portions of the machinery hit particularly hard obstructions, various parts of the cutting apparatus break away. The holder is usually the weakest point of the cutting apparatus, and accordingly the holders are commonly broken and must be replaced. In addition, a great deal of strain is placed on the drive mechanism as the bulky parts of the cutting apparatus strike these obstructions, sometimes preventing the cutting apparatus from rotating.
Taking a cutting machine out of operation for repair of the cutting apparatus is a very costly exercise. One expensive cost component associated with repairing the cutting machine is the loss of potential revenue which cannot be obtained while the cutting machine is out of operation.
Various techniques have been developed in order to simplify the replacement of holders on a cutting apparatus in a cutting machine. One method involves the use of a holder having a T-shaped shank which can be slidably inserted into a base portion which is welded directly onto the mounting block. When the holder breaks away, any remaining portion of the holder can be slid out of the base a new holder can be reinserted. This does to some extent reduce the amount of time taken to repair the cutting apparatus.
Another problem associated with known cutting apparatus is that as the cutting apparatus is rotated, the various bulky protruding sections of the apparatus come into contact with the surface being worked a cause considerable stress on the drive mechanism which drives the cutting apparatus. Repairing the drive mechanism can be costly and time consuming.
It is accordingly desirable to provide a cutting apparatus which is relatively simple to repair to minimise the time during which the cutting machine is out of operation.
According to the present invention there is provided a cutting apparatus which includes:
a rotatable member having an outer surface; and
a plurality of cutting tool assemblies, each assembly including a cutting tool mounted in a holder,
wherein the cutting tool assemblies are mounted on the rotatable member so that the holder is shielded by the rotatable member and the cutting tool extends beyond the outer surface of the rotatable member a sufficient distance to operate as a cutter.
As is well known in the art of the invention, holders are usually used for receiving cutting tools because the cutting tools generally need to be received in a region of high-strength (and therefore higher quality and more expensive) metal. It is generally cheaper to provide a separate holder of high-strength material, rather than an entire rotatable member made from high strength material. However, it is possible for the holder to be integral with the rotatable member. In this case, the rotatable member could be made entirely from the high-strength steel, and a region of this member which receives and supports the cutting tool constitutes the holder of the cutting tool assembly.
By providing a rotatable member which shields the holder of the cutting tool assembly the problem associated with breaking cutting holders is avoided. In particular, when only the cutting tool extends beyond the outer surface of the rotatable member, only the cutting tool is subjected to forces which may result in breakage. The cutting tool can be simply and inexpensively replaced by removal of any broken portion of the cutting tool and replacement with a new cutting tool.
It is less expensive to replace a cutting tool than the entire holder or block of the rotatable member of the prior art. The cutting tool is approximately eight times less expensive than the holder. In addition, according to a preferred embodiment, the cutting tool is merely seated with a retaining clip in the holder and is not bolted, welded or otherwise affixed rigidly thereto. It takes much less time to replace the cutting tool than it does to replace the entire cutting tool assembly or block. In the prior art, when the holder or block breaks, this must be re-welded or bolted onto the mounting block. This takes much more time, and often cannot be done on site.
Preferably, the shielding is provided in a region to the side of and/or in front of the holder in the direction of rotation of the rotatable member. The shielding may be provided in a region diagonally in front and to the side of the holder, in the direction of rotation of the rotational member.
Preferably, the portion of the rotatable member defining the outer surface of the rotatable member shields the holder.
It is preferred that the outer surface of the rotatable member be substantially continuous in the sense that any breaks or crevices in the outer surface are not so large or are not located so as to cause stress on the mechanism driving the rotatable member. The idea behind this is that the rotating outer surface of the rotatable element should ride relatively smoothly over the surface being removed, with only the cutting teeth extending beyond the outer surface and into the material being cut. Accordingly, it may be possible for there to be small breaks or irregularities in the outer surface, provided that the arrangement of these breaks is not much as to alter the relatively smooth rotation of the outer surface over the surface being cut. Accordingly, it is a preferred feature of the invention that the outer surface of the rotatable member be shaped to enable the rotatable member to maintain continuous contact with the surface being cut as it rotates in a cutting operation. More preferably, the rotatable member maintains smooth continuous contact with the surface being cut during the cutting operation.
The object of this embodiment is to ensure that the teeth do the work in cutting the surface being cut, and not any irregular or protruding parts of the cutting apparatus. This also ensures that the rotational driving force is primarily transferred into cutting force as exposed to stress forces arising from irregular contact with the surface being cut.
It is particularly advantageous to provide smooth continuous contact between the rotatable member and the surface being cut, since this substantially reduces the impact loading on the drive mechanism for the rotating cutting apparatus, and ensures that the cutting tools principally do the cutting work, and are subjected to the stress of striking the surface being cut. In one commonly known cutting apparatus, the bulky mounting block and cutting tool assemblies are unevenly randomly distributed about the surface of the rotatable drum. This results in irregular impact and strain being applied to the drive mechanism an to the cuttin
Schibeci Anthony Richard
Schibeci Joseph Mark
Schibeci, Jr. Anthony Richard
Anthony Richard Schibeci Watsonia
Burns Doane , Swecker, Mathis LLP
Shackelford Heather
Singh Sunil
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