Tunnel boring machine

Abstract: Tunnel boring machine whose driving shaft (4) adjacent to the boring head (6) is journalled in a bearing (12) which is intended to take up only radial forces. Shaft (4) is at its other end journalled in bearings (13,14) which take up both radial and axial forces.

Description: The present invention relates to a tunnel boring machine, i.e. a machine by means of which a tunnel is bored to full area without using explosives. In a prior art tunnel boring machine, see GB-A-1 295 152, the driving shaft for the boring head is journalled in both radial and thrust bearings at its front end. In order to handle the large thrusts the thrust bearing must have a comparatively large diameter. It has long been a desire to be able to construct machines of the above mentioned kind for different tunnel diameters and thereby use module designs which are the same for the different tunnel diameters. Machines designed according to these ideas would be substantially cheaper because fewer parts need be specially designed for individual machines. Machines which comply with the above mentioned desire must have a driving shaft for the boring head which can stand the torque which the biggest machine requires. This gives a large diameter. At the same time the bearing adjacent to the boring head must admit passage, for instance for exchange of boring tools, in the smallest contemplated tunnel diameter. The present invention, which is defined in the subsequent claim, aims at achieving a tunnel boring machine which admits the mounting of boring heads with comparatively different diameters on the same driving shaft. This is achieved by, contrary to prior art, journalling the driving shaft for the boring head adjacent to the boring head only in a bearing which is only intended for radial forces. Through this a substantial diameter reduction of the design is obtained directly behind the boring head. The axial forces are transferred from the machine housing via bearings at the rear end of the machine to the rotational shaft for the boring head and from there to the boring head. An embodiment of the invention is described below with reference to the accompnying drawing which schematically shows a section through a tunnel boring machine according to the invention. The tunnel boring machine shown in the drawing comprises a machine housing 1 which by means of hydraulic cylinders 15 and clamping shoes 16 is clampable in a tunnel 2. A shell 3 is movable to-and-fro in the machine housing and prevented from rotation about its longitudinal axis by the machine housing. In shell 3 a shaft 4 is rotatably journalled. Shaft 4 carries at its front end 5 a boring head 6 which is provided with a number of cutters 7, one shown, for the working of a tunnel front 11. Shaft 4 is at its front end journalled, by means of a bearing 12, in the shown example a spherical roller bearing, which is only intended for the taking up of radial forces, in shell 3. Shell 3 is supported adjacent to bearing 12 by a not shown support foot. The drawing shows the tunnel boring machine from above making the support foot obscured. Shell 3 is at its end 7 far from the boring head provided with a gear box 8 on which a number of driving motors 9 are arranged. Shaft 4 is by means of bearings 13,14, in the shown example conical roller bearings,journalled in the gear box 8. These bearings are intended for the taking up of both radial and axial forces. The outgoing shafts of the driving motors transfer torque via the gear wheel 18 to shaft 4. In order to press boring head 6 against the tunnel front 11 a number of pressure fluid cylinders 10 provided with piston rods 48 are arranged between machine housing 1 and shaft 4 via gear box 8. Gear box 8 is provided with two hydraulic cylinders 19 which carry not shown support feet. In order to adjust the machine to different tunnel diameters boring head 6 can be exchanged, driving motors 9 can be exchanged or the number of driving motors can be changed. Furthermore, the number of clamping shoes 16 can be adjusted to the transferred torque.

Claims: Tunnel boring machine comprising a machine housing (1) which is clampable in a tunnel (2), a shell (3) movable to-and-fro in the machine housing, a shaft (4) rotatably journalled in said shell (3), said shaft (4) at one (5) of its ends carrying a boring head (6), said shell (3) at its from the boring head (6) directed end (7) being provided with a gear box (8) on which a number of driving motors (9) are arranged, and a number of pressure fluid cylinders (10) being arranged between said machine housing (1) and said shaft (4) in order to press said boring head (6) against a tunnel front (11), characterized in that said shaft (4) adjacent to the boring head (6) is journalled in said shell (3) only by means of a bearing (12) intended to only take up radial forces, at said gear box (8) is journalled by means of bearings (13,14) which take up both radial and axial forces and that said pressure fluid cylinders (10) are arranged between said machine housing (1) and said gear box (8).

Inventors: HARTWIG SVERKER, HARTWIG, SVERKER
Applicants: ATLAS COPCO CONSTR & MINING, ATLAS COPCO CONSTRUCTION AND MINING TECHNIQUE AB
Application year: 1991
Main classification: E21D9
IPC codes: E21D9