GB2233010A

GB2233010A - Underground excavator

Info

Publication number: GB2233010A
Application number: GB8913519A
Authority: GB
Inventors: Hakumi Hagimoto; Yutaka Kashima; Norio Kondo; Tsutomu Tomisawa; Kiichi Honma
Original assignee: Daiho Construction Co Ltd
Current assignee: Daiho Construction Co Ltd
Priority date: 1989-06-20
Filing date: 1989-06-13
Publication date: 1991-01-02
Anticipated expiration: 2009-06-13
Also published as: FR2648511A1; GB8913519D0; GB2233010B; FR2648511B1; DE3920163C1

Abstract

An underground excavator includes a rotary cutter (12) mounted to the forward end of a rotary shaft (13), the latter being mounted for axial rotation and simultaneous rocking in the axial direction. The cutter is provided with a conical cutter face plate (21) having holes (24) for passing therethrough the excavated material and diametered smaller than an opening of excavated-material discharging means (25) disposed in a chamber (16). Thus material of a size larger than the holes (24) is moved quickly along the conical cutter face plate toward the peripheral ground layer by the rocking motion of the conical cutter face plate simultaneously with the rotation of the cutter during advancement of the excavator. <IMAGE>

Description

1 1 1 :2:2 a 3 0 1-

-1"UNDERGROUND EXCAVATOR" SPECIFICATION TECHNICAL BACKGROUND OF THE INVENTION

This invention relates to an underground excavator having a chamber defined in forward end part and a rotary cutter mounted to forward end of a rotary shaft held to penetrate through the chamber, such ground-forming stuffs as soil, sand, gravel, clay and their mixture excavated by the cutter being received in the chamber.

The underground excavator of the kind referred to is to be placed in vertical shaft bored in the ground and driven horizontally from the shaft into the ground to excavate the same, so as to be effectively employed for installation of pipes, for example, with Hume concrete is Dipes or the like, or for providing a tunnel through the ground which is, in particular, high in the content of relatively layer gravel.

DISCLOSURE OF PRIOR ART

In installing, for example, the pipes embedded underground, in general, a vertical shaft is bored into the ground to a desired depth for embedding the pipes, and a leader pipe and pipes are driven from this vertical shaft horizontally into the ground, but this has been involving such a problem that the driving of the pipes from rearward end becomes impossible when resisting force of the ground is large, or, in the high gravel content ground layer, the gravel accumulating at forward end of the leader pipe will hinder the leader pipe and following -2pipes from advancing any more or at least cause them to deviate from intended advancing route for the pipe way installation.

In Japanese Patent Publication No. 57-39359 of M.

Mituwa, for example, there has been suggested an underground excavator provided, instead of the foregoing leader pipe, with an excavating cutter which functions to excavate the ground and further to crush the gravel. More concretely, this excavator includes a chamber defined in forward end part for receiving therein the groundforming stuffs excavated, a rotary shaft is disposed to penetrate through this chamber, and an excavating cutter having at forward end part tunnel-face ground cutting bits as well as gravel crushing bits. With this underground excavator employed, the excavation through the ground can be carried out more effectively even through the ground involving the large resisting force or high in the gravel content including the larger gravel, than in the conventional measure of employing only the leader Dipe, in respect o--':

the possibility of excavating the ground with any hindering matter removed, with improved excavating ability and velocity. However, there still have been problems in that the concurrent provision of the gravel crushing bits along with the ground cutting bits has rendered the manufacturing costs for the excavating cutter and eventually the excavator to be high, and that, when the high gravel-content ground is relatively soft in other stuffs than the gravel, a low holding force of the ground "., 10 for the respective gravel pieces yields only a small stress in the gravel pieces even when hit by the gravel crushing bits so that the gravel will stay in the advancing route of the excavator to have its advance made almost impossible.

In Japanese Patent Publication No. 61-30118 of M. Araki, further, there has been suggested another underground excavator having a crushing chamber defined in forward end part of the excavator and disposing therein a plurality of roller bits of generally conical-shape for crushing larger gravel, penetrate through the a rotary shaft disposed to chamber and a spoke-shaped excavating cutter mounted to forward end of the shaft and including excavating bits. With this excavator, t h e gravel can be taken into the crushing chamber so as to be crushed as held between the larger-gravel crushing roller bits made integral with rearward face of the cutter and inner peripheral crushing wall of the crushing chamber so that the larger gravel in particular will be prevented from accumulating in the advancing route of the excavator, and excavating function can be more improved than in the case of the foregoing Publication No. 57-39359.

Notwithstanding such advantage, however, the excavator is complicated in the larger gravel crushing arrangement and, yet, it is made necessary to couple to the rotary shaft a high output driving power source in order that the gravel large in size and high in the hardness among various gravel of largely variable diameter size and hardness can be reliably crushed. Further", the larger-gravel crushing bits are rapidly worn out due to repeated contact with the gravel f or its crushing, and there has been a problem in the durability. Therefore, there still remains a problem in the economy due to that manufacturing costs of the excavator is increased to a large extent.

TECHNICAL FIELD

A primary object of the present invention is, therefore, to provide an underground excavator which can remove the foregoing problems so as to be particularly useful when employed in installing pipes, in particular, through the larger gravel ground and the like or even in boring a tunnel through such a ground while successfully rendering the manufacturing costs to be effectively lowered.

According to the present invention, the above object can be attained by an underground excavator in which a cylindrical body defines in forward end part a chamber with a bulkhead for receiving excavated soil, gravel and the like ground-forming stuffs, a rotary shaft passed rotatably through the bulkhead is projected into the chamber, a driving power source for the rotary shaft is disposed behind the bulkhead, an excavating cutter is mounted to forward end of the rotary shaft, and means having an opening in the chamber is provided for discharging therefrom the excavated stuffs, the excavating cutter having a cutter face plate provided with a plurality of cutter bits and a plurality of holes for is passing therethrough the excavated ground-forming stuffs, characterized in that the rotary shaft is provided to be shiftable in its axial direction with the excavating cutter mounted thereto, the cutter face plate of the cutter is formed in a conical shape, and the opening of the discharging means is of a diameter larger than the holes in the cutter face plate.

According to the underground excavator of the cutter gravel of the conical forward and rearward rocking motion of the excavating cutter integral with the rotary shaft axially shifting forward and rearward, so that the gravel in front o'." the cutter face plate will be replaced by other ground-forming stuffs in circumferential ground of the excavator and embedded into ground zone adjacent outer periphery of the pipes installed or tunnel bored, that is, moved to a position not hindering the advancement of the excavator. In other words, the holes made in the cutter f ace plate to be smaller than the opening of the discharging means provided to follow the chamber are also effective to cause the gravel exceeding the gravel size practically capable of being discharged through the discharging means not to be received in the chamber but to be eventually embedded into the circumferential ground about the excavator.

foregoing arrangement, the conical surface of the face plate causes, as the excavator advances, any present in the ground of the advancing route excavator to be urged to gradually shift along the surface radially outward while being subjected to Other objects and advantages of the present invention shall be made clear in following explanation of the invention detailed with reference to preferred embodiments thereof shown in accompanying drawings.

BRIEF EXPLANATION OF THE DRAWINGS FIGURE 1 is a schematic sectioned view in an embodiment of the underground excavator according to the.present invention; FIG. 2 is a front view of the excavating cutter in the excavator of FIG. 1; FIGS. 3 and 4 are explanatory views for different aspects of the through holes made in the excavating cutter empolyed in the excavator of FIG. 1; and FIGS. 5 and 6 are fragmentary sectioned views showing other embodiments of the excavating cutter in the present invention.

While the present invention shall now be explained with reference to the embodiments shown in the accompanying drawings, it should be appreciated that the intention is not to limit the invention only to such embodiments but rather to include all alterations, modifications and equivalent arrangements possible with the scope of appended claims.

DISCLOSURE OF PREFERRED EMBODIMENTS

Referring here to FIGS. 1 and 2, there is shown an underground excavator employable in installing underground pipes such as Hume concrete pipes. For the pipe installation, the excavator is made to be of an outer -7diameter of 20 to 40 cm, but the diameter may properly be varied in accordance with required diameter of the pipes to be installed. Not only for such pipe installation, the present invention is also applicable, as will be readily appreciated, to tunnel borings by means of, for example, a shield type tunnel boring system, in which event the excavator may be of any outer diameter adapted to required tunnel diameter, for example, several meters.

More concretely, the underground excavator 10 generally comprises a cylindrical body 11, and an excavating cutter 12 provided to forward end part of the body 11. The excavating cutter 12 is mounted to a forward end of a rotary shaft 13 to be rotated therewith, while the rotary shaft 13 per se is positioned on the axis of the body 11 as- supported through a shaft bearing 14 by a bulkhead 15 in axially rotatable and shiftable manner, and a chamber 16 into which ground-forming stuffs are led from the ground is defined between the excavating cutter 12 and the bulkhead 15. In the cylindrical body 11, further, a fixing plate 17 is provided at a rearward position from the bulkhead 15, a reversible motor 18 having an output pinion 19 is secured to the fixing plate 17, and a driving gear 20 mounted about the rotary shaft 13 is made in mesh with the pinion 19. In this case, the driving gear 20 is spline-coupled to the rotary shaft 13 so that, while an output rotary force of the motor 18 is transmitted through the gear 20 to the shaft 13, the gear 20 will be relatively shiftable in axial direction of the shaft 13.

is The excavating cutter 12 comprises, on the other hand, a cutter face plate 21 substantially of a conical surf ace as a whole, and this cutter face plate 21 is provided with a central cutter bit 22 projected to be at the forwardmost 1Dosition in the center of the plate corresponding to the forward tip end of the rotary shaft 13 and with a plurality of peripheral cutter bits 23 disposed preferably to extend radially inward from the outermost periphery of the plate 21 and to project thereout in forward direction.

In the conical surface of the cutter face plate 21, further, a plurality of through holes 24 are made between adjacent ones of the respective peripheral cutter bits 23.

Conic angle of the cutter face plate 21, that is, an angle 6 defined by a line connecting between the top point A and a peripheral point B with respect to a line intersecting at right angles the axial line of the shaft 13 should properly be selected to be one oil various angles within 45 degrees on the basis of such conditions as geologic nature of the ground through which the pipe way or tunnel is to be made.

In a lower portion of the cylindrical body 11, further, such discharge means 25 as a screw conveyor or the like is provided, so that a forward end opening 26 as an inlet port of the discharge means 25 will be positioned at a lower portion in the chamber 16 while substantial body of the means 25 extends rearward beyond the bulkhead and fixing plate 17 so as to discharge the ground-forming stuffs excavated and led into the chamber 1 16 through the opening 26 rearward of the bulkhead 15 and fixing plate 17. In dealing with the excavated ground-forming stuffs, generally, a hydraulic discharge system is employed, while a pressurized mud system may also be employed. When the hydraulic discharge system is employed, a pressurized slurry feed pipe (not shown here) is provided, for example, as passed through the axis of the rotary shaft 13 and the bulkhead as well to continuously supply a pressurized slurry into the chamber 16 for providing a slurry pressure capable of resisting ground pressure at tunnel face being excavated, while the ground-forming stuffs excavated and taken into the chamber 16 is discharged therefrom through the discharge means 25 I= as carried by the supplied slurry into the opening 26.

required, any additive solvent, viscosity-providing agent or the like may be added to the slurry. As will be readily appreciated, a mixture of the slurry and the ground-forming stuffs and discharged through the discharge means 25 is led, for example, to a slurry setting vessel installed on the ground surface (not shown) for recirculating use. When, on the other hand, the pressurized mud system is utilized, an agent for causing highly fluidible mud to set to some extent is fed into the chamber 16 through a pipe provided to pass through the axis of the rotary shaf t 13 as has been known per se, so as to form continuously in the chamber 16 a pressurized and rather viscous mud resisting the tunnel face ground pressuref and such pressurized mud is sequentially -10discharged by such discharge means as a screw conveyor to the exterior, keeping the state of the pressurized mud.

Further, a cam 27 is secured to the rotary shaft 13 to be positioned behind the bulkhead 15 and brought into rolling contact with rollers 30 born by bearings 29 integrally provided on a support plate 28 secured in the body 11 between the bulkhead 15 and the fixing plate 17.

In the nresent instance, the cam 27 has a wavy cam surface so that, as the rollers 30 roll on the wavy cam surf ace, the rotary shaft 13 carrying the cam 27 will be caused to shif t forward and rearward in the axial direction. The rotary shaf t 13 carries at its rearward end terminating behind the fixing plate 17 a support disk. 31 which does not follow the rotation of the shaft 13 but does its forward and rearward shift, a resetting spring 32 is disposed between the fixing plate 17 and the support disk 31 so as to be compressed by the forward shift of the shaft 13 under the rolling contact of the rollers 30 with the wavy cam surface of the cam 27 being rotated and, thereafter, to resiliently reset the shaft 13 rearward. Further, the cylindrical body 11 is to be propelled in a manner known per se by means of propelling jacks 33 (while only one is shown) disposed to engage tail end portion of the body 11 as mutually spaced in circumferential direction, or by a separate propelling means provided to push the rearward end of the pipe way installed behind the excavator.

Referring next to the operation of the underground (1.1 excavator according to the present invention, the reversible motor 18 rotated in either direction causes, through the output pinion 19 and driving gear 20, the rotary shaft 13 in the spline-coupling with the gear 20 to be rotated to eventually rotate the excavating cutter 12, and the tunnel face ground is thereby excavated, upon which the rolling contact between the wavy cam surface of the cam 27 on the shaft 13 and the rollers 30 renders the forward shift resisting the resetting force of the spring 32 and the rearward shift due to the resetting force of the spring 32 to be repeated, and thus the rotary shaft 13 is caused to simultaneously perform the rotation about the axial line and the shift along the axial line. In this case, the forward and rearward shift of the' rotarv shaft is 13 should preferably be so set that the maximum clearance between the forward end edge of the body 11 and the outer peripheral edge of the cutter face plate 21 (see FIG. 1) will effectively prevent any relatively large or elongated gravel from entering into the chamber 16.

The ground-forming stuffs excavated at the tunnel face are to be led into the chamber 16 mostly through the through holes 24, and are conveyed through the opening 26 to rearward position of the body 11 by the discharge means 25. The through holes 24 are of the smaller diameter than the opening 26 of the discharge means 25, and any gravel of a larger dimension than the opening 26 can never be present in the chamber 16.

Now, in an event where many gravel including the i 1k -12larger gravel is pres6nt in the tunnel f ace ground, such gravel is subjected to a selection of the larger gravel not allowed to pass through the holes 24, out of the gravel receivable into the chamber, the larger gravel is caused to move quickly along the conical cutter face plate 21 which is being rocked due to the axial f orward and rearward shift during the rotation of the cutter 12, so as to shift radially outward as the excavator advances, the larger gravel is gradually replaced by other stuffs forming the ground sideway around the body 11 and urged to be embedded into the sideway ground.

The propelling jacks 33 are driven in conformity to the excavation of the ground to propel the body 11 forward, the pipes are sequentially installed or, in the case of the tunnel boring, the peripheral wall surface of the tunnel newly appearing behind the body 11 propelled is retained, if necessary, and the tunnel boring can be smoothly realized.

In the present invention, various design modifications can be adopted. For example, the through holes 24 made in the cutter face plate 21 are not limited to be circular as shown, but it may be possible to employ such elliptic through holes 24a as shown in FIG. 3, or such rectangular through holes 24b rounded at corners as shown in FIG. 4.

It has been found in this respect that the ratio of the minimum width to the maximum width should preferably be set in a range of 1:1 to 1:1.5. Further, it will be also possible to employ such excavating cutter 112 having a -13cutter face plate 121 of stepped conical shape as shown in FIG. 5 in which the conic angle of the plate 121 varies at an intermediate position, or such cutter of a cutter face plate 221 of curved conical shape as in FIG. 6 to be more or less dome shaped.

Further, while the arrangement for the axial forward and rearward shift of the rotary drive shaft has been referred to as being attained by means of the rolling contact between the cam having the wavy cam surface and the rollers, such various ones of other arrangement that employs hydraulic jacks of oil or pneumatic pressure for reciprocal motion, crank system or the like may equally be utilized.

is

Claims

What is claimed is:

1. An underground excavator comprising a cylindrical body, a chamber defined in forward end part of said cylindrical body with a bulkhead, a rotary shaft passed rotatably through said bulkhead and projected into said chamber, means provided for shifting said rotary shaft forward and rearward, a drive power source disposed behind said bulkhead and coupled to said rotary shaft, an excavating cutter including a cutter face plate of a conical shape and provided with a plurality of cutter bits and a plurality of through holes, said excavating cutter being mounted to forward end part of said rotary shaft, and means having an opening in said chamber and of a diameter larger than said through holes for discharging excavated ground-forming stuffs from the chamber through said opening to a position-behind said bulkhead.

2. An excavator according to claim 1 wherein said through holes are made to have a ratio of the minimum width to the maximum width in a range of 1:1 to 1:1.5.

3. An excavator according to claim 2 wherein said through holes are circular.

4. An excavator according to claim 1 wherein said means for shifting said rotary shaft forward and rearward comprises a cam secured to said rotary shaft to be behind said bulkhead and having a wavy cam surface having alternately continuing concave and convex portions extending in axial direction, and a roller brought into a rolling contact with said wavy cam surface of said cam for A - is - directly causing the shaft to shift forward and rearward.

5. An underground excavator. comprising a cylindrical housing, a perforate externally-convex member which has external cutting elements provided thereon and which generally closes a forward end of the housing means for rotating the convex member about the axis of the housing, and means for conveying from the housing material of a size which can pass through the perforations in the convex member.

6. An excavator as claimed in claim through holes are circular.

5, wherein the

7. An underground excavator substantially as described with reference to the drawings.

Published 1990 at The Patent Office. State House. 66 71 High Holborn, London WC1114TP.Purther copies maybe obt,-unedfrorn The Patent Office Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent, Con. 1'87

6. An excavator as claimed in claim 5, further comprising means for reciprocating the convex member in the longitudinal direction relative to the housing.

Amendments to the claims have been filed as follows CLAIMS 1. An underground excavator, comprising a cylindrical body, a bulkhead within the cylindrical body so that a chamber is defined to a forward side of the bulkhead, a rotary shaft passing through the bulkhead and projecting into the chamber, an excavating cutter mounted on the forward end of the rotary shaft, and including a conical cutter face plate having a plurality---ofcutter bits and a plurality of through-holes, a drive power source disposed behind the bulkhead and arranged to rotate the shaft and cutter, means for reciprocating the shaft and cutter in the direction of the axis of the shaft and means for discharing excavated material from he chamber through an opening through the bulkhead having a size greater than the size of the holes in the cutter face plate.

2. An excavator as claimed in claim 1, wherein the reciprocating means comprises a camming arrangement having a first portion secured to the shaft and a complementary second portion secured relative to the cylindrical body so that the camming arrangement 25 produces reciprocation as the shaft rotates.

1 1 3. An excavator as claimed in claim 2, wherein one of the portions of the camming arrangement comprises a cam member having an undulating surface, and the other portion comprises a roller which follows the undulating surface upon rotation of the shaft.

4. An excavator as claimed in claim 3, wherein the cam member is secured to the shaft, and the roller is rotatably supported relative to the cylindrical body.

5. An excavator as claimed in any preceding claim, wherein the throughholes in the cutter face plate have a ratio of their minimum width to their maximum width in the range 1:1 to 1:1.5.