CA1051932A

CA1051932A - Tunnel boring machines

Info

Publication number: CA1051932A
Application number: CA270,733A
Authority: CA
Inventors: Carlo Grandori
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-02-02
Filing date: 1977-01-31
Publication date: 1979-04-03
Also published as: AU2158077A; FR2339736A1; ES455484A1; IT1053909B; DE2703468A1; SE7700866L; FR2339736B1; ZA77370B; AU504757B2; JPS5294629A; GB1526702A

Abstract

AN IMPROVEMENT IN THE TUNNEL BORING MACHINES

Abstract of the Disclosure A machine for use in mechanlcal tunnel borlng of the rotating cutter head type. A grid is fixed to the cutter head and has a surface generally parallel to the theoretical boring surface. The grid is provided with a plurality of void spaces from which the autting tools of the cutter head protect slightly. The void spaces have a size corresponding to the desired optimum dimensions of the fragments of the material removed in the boring opening.

Description

~5~932 The invention relates to an improvement in the present machines for the mechanical tunnel boring, and particularly in those machines which by a single tool, called a cutter head, bore the entire cross-sectional area of the tunnel, and wherein the head revolves about an axis coincident with that of the tunnel.
Up to now, the possibility of satisfactory use of said machines is restricted to the grounds,the boring front of which, is self-supporting.
According to this invention a device is disclosed which is capable of being applied to rotary cutter heads either already constructed, or to be constructed, thereby allowing such machines to be used also where the boring front consists of an entirely or partially not self-supporting ground.
As is known to persons skilled in the art, the cutter heads of the existing machines are provided with tools of various kinds. For soft rocks said tools consist generally of cutters having various shapes; for hard rocks the tools are generally discs idly mounted on the cutter head, and rotating about axes located according to the radii of the head itself. Each disc is provided with one or more rings made of very strong and hard material, with sharp edged corners, or with embedded buttons of hard material.
The tools of the cutters for soft rocks will scrape the front and bore into it by an action like that of a "ripper", or of a lathe or planing tool.
The tools for hard rocks operate by concentrating on the rock, through the sharp cornered ring, or the buttons, a heavy concentrated load breaEing the over-loaded zone by internal stress.
In both cases, namely for the soft rocks and for the hard rocks, in stable and uniform conditions of the ground, the ~L
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excavated material consists of elements the rnaximum sizes of which are about 2 x 8 x 15 cms for the hard rocks, while said sizes increase for the soft rocks up to lS x 20 x 30 cms, and sometimes also more.
The distance measured along the axis of rotation from the boring surface to the surface of the tool-carrying structure has always a remarkable value, also for constructive requirements, and any way sensibly greater than that of the greatest element produced by the boring operation.
The excavated material can fall between the tool support, namely the rotary cutter head, and the tunnel face, and is collected by a set of shovels, with which the head is provided, and is carried by these shovels on a continuous conveyor belt, carrying said material behind the cutter head.
By an arrangement of this kind, in various applications, drawbacks set out hereafter frequently have been noted in all types of cutter heads used up to-day.
When the boring front is unstable, and collapses, partial-ly or entirely, both in the cutter head for soft rocks and in those for hard rock, the material which moves away from the front invades the space between said boring front and the cutter head thereby increasing the resistance against rotation up to a possible jamming thereof.
In other cases, the volume of the product of the boring operation is greater than the volume corresponding to the for~ard movement and to the bored section, so that recesses will be generated, with the risk of collapsing and setting of the ground. In these cases, it is compulsory to stop the operation of the cutter head and either it will be necessary to carry out reinforcing works, or it will be required to progress before the cutter head with conventional systems, until the diffi~ulties ~OS1~3Z

will be overcome.
Another very frequent drawback, which occur8 for instance in cracked rocks or in rocks including alternated layers of soft rocks and hard rocks, is the breakaway from the front, also under the action of the cutter heads themselves, of blocks having such dimensions that the pick-up shovels cannot take said materials and/or the predisposed means cannot remove said mined materials.
Thereby damages will occur to the tools, their supports, and/or to the conveying and removing means, with the consequent discontinuances of work for the manual removal of the blocks or the repair of the damages.
This invention is intended to minimize these drawbacks reducing as much as possible their occurrence.
According to this invention a grid is mounted on the cutter head parallel to the theoretical boring surface, and is provided with a plurality of void spaces from which slightly project the crushing tools or cutting elements, said void spaces having a size corresponding to the "optimum" sizes of the fragments of mined material.
Thus according to the present invention there is provided a tunneling machine cutterhead of the rotary type which in use is advanced in a direction coincident with its axis of rotation and which comprises forwardly directed cutters having cutting portions for cutting concentric kerfs in the tunnel face, and passageways through which excavated material passes, characterized in that said cutterhead includes a rigid forward grid structure thereon having a forward face which is substantially parallel to the theoretical tunnel face, and said 30 cutters are mounted on the cutterhead rear~ardly of said grid ~,, <~ .
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structure, with the cutting portions thereof projecting slightly forwardly of the forward face of the grid structure so as to penetrate into the cutter face, said grid structure comprising a plurality of radially spaced apart concentric breasting rings with gauge openings defined radially between them corresponding to the optimum dimension of fragments of excavated material, and positioned such that all excavated material must pass through a said gauge opening before entering a said passageway.
According to a preferred embodiment of the present invention said grid consists of a plurality of annular bands, concentric with the axis of rotation of the cutter head and so radially spaced apart from one another as to allow the passage therethrough of excavated material, the size of which is less than a predetermined value. Also, the axial distance of said bands from the body of the cutter head is related to said predetermined value.
This invention will now be described with reference ~-to the attached drawings, showing by way of non-limitative example one preferred embodiment of the invention itself.

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In the drawings:
Figure 1 is a front elevation view of a boring cutter head, having a spoke structure, and equipped with the device according to this invention;
Figure 2 is a cross-sectional view taken along the line II-II of Figure l;
Figure 3 located in the same sheet as Figure 1 is a cross-sectional view taken along the line III-III of Figure 1:

Figures 4 and 5 located in the same sheet as Figure

2 show details of a variant of the cutter head of Figure 1, in partial elevation, and in cross-sectional view taken along the line V-V of Figure 4, respectively;
Figure 6 is a view similar to Figure 1, showing this invention when applied to a closed type cutter head;
Figure 7 is a cross-sectional view taken along the line VII-VII of Figure 6;
Figure 8 located on the same sheet as Figure 6, is a cross-sectional view taken along the plane VIII-VIII of Figure 6, in an enlarged scale; and :
Figure 9 located on the same sheet as Figure 7, shows a cross-sectional view taken along the plane IX-IX
of Figure 8.
With reference to Figures 1 to 3, the numeral 1 denotes the spokes of an "open" type cutter head. The spokes 1 have a box-like structure, and each of them is provided with a set of fork-like supports 2 carrying crushing or cutting rollers or discs 3, idly mounted on said supports, and rotatable about axes radially located with respect to the cutter head.

105~932 Said cutter head rotates as shown by the arrow F in Figure l, and is connected to the internal stationary structure 4 by means of the rolling bearings 5.
The material coming from the boring face 10 is taken by the radial shovels 6 inclined towards said face 10 and by the curvilinear peripheral chutes 7 carried by said shovels and is conveyed, as shown by the arrows of Figure 2, into the hopper 8, which is a part of the stationary structure down-stream of the cutter head. At the bottom of the hopper 8, a belt conveyor 9 carries the mined material out of the tunnel.
This invention provides for a grid consisting of a concentric set of metal annular rings ll, having an adequate thickness, subdivided into sectors, welded or fixed to the ends of the radial shovels 6 and to the supports 12 of Figure 2. As it is clearly shown in this Figure, the position of the grid 11 with respect to the base of the cutter head is such that only the cutting discs 3 will project from the grid itself. In correspondence with the peripheral zone of the cutter head, the annular band 11 is shaped as shown in 13 in order to protect the peripheral zone when the outer discs 14 operate.
In Figures 4 and 5 where like numerals indicate the same parts already described and indicated with these numerals, the grid according to this invention is applied to one cutter head for soft rocks provided with the pairs of cutters 15 instead of the crushing discs.
One or more sectors of the grid 11 can be removable in order to allow the passage of the persons, and of the spare parts which must pass through the cutter head, as well as for allowing the periodical inspections to the tunneling front 10.
By way of example, Figures l and 3 show a system consisting of two sets of slots 16 into which is inserted a pair of locking pins.
Figures 6 to 9 show the grid according to this invention as applied to a "closed" type cutter head, consisting of a part spherical member 17 provided with a crown of shovels 18 and 19 for conveying upwards the mined material, which is then discharged on the previously described conveyor 9.
In this case, as no radial shovel exists, the annular elements 11 of the grid are fixed to the shield 17 by pairs of supports 20, as clearly shown in Figure 8.
For both described solutions, the mutual position between the grid 11 and the tool 3 must be such that the projection S (Figure 8) of the tools or discs 3 from the grid will be the minimum, taking account of the limits as follows:
namely, the limit for which the efficiency of the machine is still normal when operating~ion a stable and uniform front where the previous cited drawbacks do not occur, and the limit of the minor dimension of the biggest element as produced by the boring operation in normal conditions, (stable, non-blocky front).
The dimension of the clear part of the passage between the bands 11 of the grid, as radially measured, must not be greater than the maximum dimension of the element which can pass in the conveying means, and must not be such as to hinder the passage of the mined material in normal situation.
Downstream of the bands 11 of the grid, large passages Sl must be arranged for the material which passes directly through the grid, and/or for the material which will be loaded by the shovels mounted on the cutter head.
By the above described grid device, when the entire front of tunneling or part thereof tends to collapse, it will be supported by the annular bands 11 of the grid, while the tools projecting therefrom will cause the crushing of the bigger pieces and the passage of the little pieces. The amount of the material passing through the grid will be limited, reducing the risk of the passage of a volume greater than that corr~s-ponding to the advancement of the machine.
Likewise, if breakaway blocks having large dimensions are created during the boring operation, said blocks are held in place by the bars of the grid until the tools will gradually reduce said blocks to such dimensions as to allow their passage through the grid.
As it is evidently shown in Figures 1, ~ and 7, the grid according to thiS invention serves the shielding function also in respect of the collecting members (buckets) for the mined material, where said members operate directly in correspondence with the tunneling front.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A tunneling machine cutterhead of the rotary type which in use is advanced in a direction coincident with its axis of rotation and which comprises forwardly directed cutters having cutting portions for cutting concentric kerfs in the tunnel face, and passageways through which excavated material passes, characterized in that said cutterhead includes a rigid forward grid structure thereon having a forward face which is substantially parallel to the theoretical tunnel face, and said cutters are mounted on the cutterhead rearwardly of said grid structure, with the cutting portions thereof projecting slightly forwardly of the forward face of the grid structure so as to penetrate into the cutter face, said grid structure comprising a plurality of radially spaced apart concentric breasting rings with gauge openings defined radially between them corresponding to the optimum dimension of fragments of excavated material, and positioned such that all excavated material must pass through a said gauge opening before entering a said passageway.

2. A tunneling machine cutterhead according to Claim 1, said cutterhead comprising a plurality of radial spokes and axial passageways between the spokes through which excavated material passes, and wherein a substantial number of the cutters are mounted on each of said spokes and wherein the breasting rings are mounted on the cutterhead to span across said axial passageways.

3. A tunneling machine cutterhead according to Claim 1, wherein the cutters are roller type cutters having peripheral cutting portions which project forwardly of the front face of the grid structure.

4. A tunneling machine cutterhead according to Claim 1, which is used in a tunneling machine which includes a conveyor for moving excavated material rearwardly in the tunnel from the region of the cutterhead, wherein the radial dimension of the gauge openings corresponds to the maximum dimension of pieces of excavated materials which can be handled by the conveyor means.

5. A tunneling machine cutterhead according to Claim 1, in which the grid structure is divided into sections and at least one of such sections is removable to provide an access avenue for inspection of the region forwardly of the cutterhead.