Tunnel boring machine

Abstract: Tunnel boring machine comprising a number of swingable arms (11,12,13,14) provided with boring tools (41,42,43,44) for the working of the tunnel wall outside its normal diameter.

Description: The present invention relates to a tunnel boring machine, i.e. a machine which bores a tunnel without the use of explosives. During boring with a tunnel boring machine the boring head is pressed against the tunnel front with large force at the same time as it is rotated. During the boring one may encounter zones with weakened rock which is supported with steel arches or reinforced in another way before the boring is continued. According to a prior art tunnel boring machine, see DE-A-31 21 244, the tunnel wall can be worked outside the diameter of the boring head by providing swingable arms behind the boring head. A drawback with this machine is that extra motors are needed in order to rotate the cutters on the swingable arms. Furthermore the prior art solution does not provide for efficient working of hard rock outside the normal diameter. The present invention, which is defined in the subsequent claims, aims at achieving a tunnel boring machine which can easily be adjusted for boring a tunnel with somewhat larger diameter to make place for insertion of steel arches. An embodiment of the invention is described below with reference to the accompanying drawings in which fig 1 shows a side view of a tunnel boring machine. Fig 2 shows on a larger scale an explaining picture of a detail in fig 1. Fig 3 shows a part of the boring head with certain parts removed for the sake of clarity. The tunnel boring machine shown in the drawings comprises a housing 1 which by means of hydraulically maneuverable clamps 2 is fixable relative to a tunnel wall 3. The machine further comprises a boring head 4 which is rotatable relative to the housing 1 about a rotation axis 10 by means of one or more driving motors 5. The boring head is provided with a number of boring tools 6 for the working of a tunnel front 7. The boring head 4 is provided with a number of swingable arms 11,12,13,14 which by means of hydraulic cylinders 21,22,23,24 are swingable about axes 31,32,33,34. The arms are provided with boring tools 41,42,43,44. The direction of rotation of the boring head is marked by the arrow 8. Boring tools 41,42,43,44 are during boring protected by plates 9 which cover the larger part of the boring tools so that only the outer part of the cutter comes in direct contact with the rock. In the position shown in fig 3 arms 11,12,13,14 are swung out against not shown stops whereby the arms during operation are kept in swung out position for the working of the tunnel wall outside its normal diameter by the forces from the tunnel wall. In fig 2 the different arms are shown as if they were in the same plane to more clearly show that the boring tools on the different arms are positioned at different distances from the axis of rotation of the boring head and at different distances from the tunnel front. Through this it is possible to obtain a larger increase of the tunnel diameter than would be the case if the boring tools were at the same distance from the axis of rotation. When the tunnel is to be driven with normal diameter the hydraulic cylinders are maneuvered so that the arms 11,12,13,14 are drawn in to their inactive positions. The boring head is furthermore provided with not shown locking means which lock the arms in extended positions or in retracted positions so that the hydraulic cylinders need not be used in order to keep the arms in place.

Claims: Tunnel boring machine comprising a housing (1) fixable relatively to a tunnel (3), a boring head (4) rotatable relatively to said housing (1), said boring head (4) being provided with a number of boring tools (6) for the working of a tunnel front (7) , a driving motor (5) for rotation of said boring head (4) and a number of swingable arms (11,12,13,14) provided with boring tools (41,42,43,44) and being swingable between a retracted inactive position and an extended position for the working of the tunnel wall outside its normal diameter, characterized in that said swingable arms (11,12,13,14) are mounted on said boring head (4) at the periphery of the boring head (4), whereby said boring tools (41,42,43,44) on the different arms (11,12,13,14) in extended positions are situated at different distances from the axis of rotation (10) of the boring head (4) and at different distances from the tunnel front (7).

Inventors: ASTRAND NILS MANFRED, FORSBERG JAN H, HARTWIG CARL SVERKER MAGNUSSON, ASTRAND, NILS MANFRED, FORSBERG, JAN H, HARTWIG, CARL SVERKER MAGNUSSON
Applicants: ATLAS COPCO CONSTR & MINING, ATLAS COPCO CONSTRUCTION AND MINING TECHNIQUE AB
Application year: 1990
Main classification: E21D9
IPC codes: E21D9, E21B10