Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Patent
1992-10-21
1994-08-30
Bagnell, David J.
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
175351, E21B 1012, E21C 2518
Patent
active
053418891
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention is related to a ring clamp for securing a cutter ring to a cutter roll on a tunnel boring machine (a/k/a T.B.M.).
BACKGROUND OF THE INVENTION
Several developments have been suggested to reduce the amount of labor in connection with replacing cutter rings on cutters for tunnel drilling machines. This work is time consuming and the T.B.M. as such is out of operation for long periods of time which to a large extent may influence the progress and also the costs.
One solution to this problem has been achieved with a divided cutter ring and especially with a wedge shaped ring clamp securing the divided cutter ring such as described in NO-PA 883 533. Although the replacement operation has been facilitated substantially, loosening of the ring clamp still may be time consuming when replacing the cutter ring segments, as the ring clamp has a tendency to jam due to the large force used when tightening the bolts.
SUMMARY OF THE INVENTION
It therefore is the aim of the present invention to provide a ring clamp for cutter rings divided into segments, which easily may be released after having been clamped. This is achieved with the ring clamp according to the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the cutter ring assembly showing the ring clamp of the preferred embodiment.
FIG. 2 is a top plan view of the preferred embodiment.
FIG. 3 is a side elevational view of the preferred embodiment along line III--III of FIG. 2.
FIG. 4 is a top plan view of the alternative to the preferred embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A well-known cutter i is provided with a cutter ring 2 with a dovetail shaped base and being divided in a number of segments which are clamped with a wedge-formed ring clamp 3.
The ring clamp is divided in segments 3A, 3B and 3C. The segments of the clamp are secured to the cutter 1 with bolts 4, whereby each bolt 4 clamps two clamp ring segments simultaneously by arranging the bolts between the segments.
The ring clamp may comprise three segments 3A, 3B, and 3C as disclosed in FIG. 2. In a modification of the present invention each of the ring clamp segments is secured with two or more bolts, the ring clamp thereby comprising two segments. The ring clamp, however, may comprise more than three segments.
In connection with known types of divided ring clamps it is known that the cutter ring 2 is very well secured to the cutter but that the dismantling and securement takes a relatively long time. The dismantling is especially time consuming. The reason is that cutters today work with an average load of up to 35,000 kp, with shock loads up to 100,000 kp. For this reason the segments must be very strongly secured. During operation the cutter ring 2 and the ring clamp 3 become heated which increases the jamming of the ring clamp segments and make dismantling extremely difficult.
All known designs of this kind of ring clamp are based on a ring clamp having the same curvature as the groove in which this is secured. The present invention eliminates the problems connected with prior art designs by manufacturing a ring clamp 3 having a somewhat larger or smaller curvature than the groove 5 in which it is to be secured, which is disclosed in FIGS. 2 and 3.
In relation to the radius r of the groove 5, the ring clamp is manufactured with a different curvature R. Arranged in the groove, the clamp segments may have a position corresponding to the dotted line 6 in FIG. 2. Here segments with an inner segment radius R larger than the groove radius r are forced into the groove. The practical effect of the difference in segment radius R and groove radius r is that the curvature of segment radius R is different from the curvature of groove radius r. When the bolts 4 are inserted and tightened, the ends of the segments are pressed into the groove. This effects a biasing of the ring clamp 3 by elastic deformation of the clamp, forced to assume the curvature of the groove. FIG. 4 shows a segment having n inner se
REFERENCES:
patent: 3981370 (1976-09-01), Bingham et al.
patent: 3982594 (1976-09-01), Ott
patent: 4004645 (1977-01-01), Rees et al.
Bagnell David J.
Stein Narvestad A.S.
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