RING CLAMP FOR A CUTTER RING IN A TUNNEL DRILLING MACHINE

Abstract: Ring clamp for securing of a cutter ring to a cutter roll in a tunnel drilling machine, the cutter ring comprising at least two segments having a dovetail shaped basis and the ring clamp (3) having a corresponding wedge shape and also comprising at least two segments (3A, 3B, 3C) whereby the segments are secured to the roll by means of bolts (4), CHARACTERIZED IN the inner radius (R) of the segments (3A, 3B, 3C) being different from the radius (r) in the groove (5) in which the segments of the ring clamp are secured.

Description: Ring clamp for a cutter ring in a tunnel drilling machine 5 The present invention is related to a ring clamp for securing of a cutter ring to a cutter roll in a tunnel drilling machine, according to the preamble of the claims. Several developments have been suggested to reduce labour work in connection with replacement of cutter rings on o cutters for tunnel drilling machines. This work is time consuming and the drilling machine as such is out of operation in long periods of time which to a large extent may influence the progress and thereby also the costs for rock drilling projects. s 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 reduced substantially, releasing of the ring clamp still may o 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. It therefore is the aim of the present invention to provide a ring clamp for devided cutter rings, which easily 5 may be released after having been clamped. This is achieved with the ring clamp according to the present invention as defined with the features stated in the claims. The present invention is described in correspondence with the drawing where Fig. 1 discloses an axial section I-I in Fig. 2, Fig. 2 discloses schematically a radial section II- II in Fig. 1 and Fig. 3 discloses a section III-III in Fig. 2. A cutter 1 is as well known, provided with a cutter ring 2 having a dovetail shaped basis and being divided in a number of segments which are clamped with a wedge-formed ring clamp 3. The ring clamp also 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 at three segments 3A, 3B and 3C as disclosed i the drawing. 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 even more than s three segments. The experience has showed in connection with known types of divided ring clamps that the cutter ring 2 is very well secured to the cutter, however the dismantling and securement takes relatively long time. Especially the o dismantling has been time consuming. The reason is that cutters today work with an average load of up to 3 500 kp with inpackt loads up to 100 000 kp. Of this reason the segments must be very strongly secured. During operation the cutter ring 2 and the ring clamp 3 are heated which increases even s more jamming of segments when the ring clamp is to be dismantled. All known designs of this type are based on a ring clamp having the same radius as the groove in which this is secured. The present invention eliminates the problems 0 connected with prior art designs by manufacturing a ring clamp 3 having a somewhat larger or smaller radius than the groove 5 in which it is to be secured, which is disclosed in Fig. 2 and 3. In relation to the radius r of the groove 5, the ring 5 clamp is manufactured with a somewhat different inner radius 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 is forced into the groove. When the bolts 4 are 0 inserted, the ends of the segments are pressed into the groove. Hereby is achieved a biasing of the ring clamp 3 by elastic deformation of the clamp, forced to assume the shape of the groove. Principally a similar effect may be achieved with 5 ring clamps having a segment radius R smaller than the groove radius r, however, with a different bolt arrangement, namely one or two bolts in the middle of each segment. When loosing the bolts 4, the biasing of the ring clamp will press the segments back to the initially unloaded shape and the ends of the segments 3A, 3B and 3C thereby are lifted out of the groove 5, making it easy to remove the segments. For furthermore to ensure that the segments easily < can be released, portions of the segments may be covered with a material having low friction, such as teflon, thereby to ensure minimum friction forces between the segments and the groove and between the segments and the bolts.

Claims: P a t e n t C l a i m s 1. Ring clamp for securing of a cutter ring to a s cutter roll in a tunnel drilling machine, the cutter ring comprising at least two segments having a dovetail shapes basis and the ring clamp (3) having a corresponding wedge shape and also comprising at least two segments (3A, 3B, 3C) whereby the segments are secured to the roll by means of bolts o (4), CHARACTERIZED IN the inner radius (R) of the segments (3A, 3B, 3C) being different from the radius (r) in the groove (5) in which the segments of the ring clamp are secured. 2. Ring clamp according to claim 1, CHARACTERIZED IN the segments (3A, 3B, 3C) being adapted for securement by s means of one bolt (4) at each end of the segment such that each bolt clamps the end of adjacent segments. 3. Ring clamp according to claim 1, CHARACTERIZED IN the segments (3A, 3B, 3C) being adapted for securement by means of at least two bolts (4). 0 4. Ring clamp according to claims 1-3, CHARACTERIZED IN the inner radius (R) of the segments being larger than the radius (r) of the groove (5). 5. Ring clamp according to claims 1-3, CHARACTERIZED IN the inner radius (R) of the segments being smaller than the 5 radius (r) of the groove (5). 0 5

Inventors: NARVESTAD STEIN, NARVESTAD, STEIN
Applicants: STEIN NARVESTAD AS, STEIN NARVESTAD A.S
Application year: 1991
Main classification: E21C25
IPC codes: E21B10, E21D9