GB2386767A

GB2386767A - Overdrill for trenchless removal of buried tubing.

Info

Publication number: GB2386767A
Application number: GB0301671A
Authority: GB
Inventors: Elmar Koch; Manfred Schauerte; Hans-Joachim Bayer
Original assignee: Tracto Technik GmbH and Co KG
Current assignee: Tracto Technik GmbH and Co KG
Priority date: 2002-01-24
Filing date: 2003-01-24
Publication date: 2003-09-24
Anticipated expiration: 2023-01-24
Also published as: GB0301671D0; GB2386767A8; GB2386767B

Abstract

An overdrill 1 fits around a conduit 2 and is pushed along the length of the conduit 2 by a rod 6. Driving means rotate cutting devices 8,9 on the overdrill 1 and rod 6 respectively to allow the overdrill 1 to advance along the conduit 2. The cutter 9 on the rod 6, may protrude further in the direction of travel to act as a pilot hole cutter. An additional cutter 10 may be provided on the overdrill 1 to act as a back-reamer.

Description

1 2386767

Device for trenchless conduit replacement The invention refers to a device for the trenchless replacement of conduits or for trenchlessly laying bare conduits with an overdrill head and in.particuiar to such devices with an overdrill head comprising fastening elements for an advancing means. To achieve trenchless conduit replacement, the soil sur-

rounding the conduit to be replaced is removed by an overdrill head driven along the conduit. Thereby the friction resistance between the conduit to be replaced and the surrounding soil is reduced when the conduit is subse-

quently pulled and pushed out the conduit, allowing the conduit to be extracted from the soil with little effort.

A device of this kind is described in the German patent DE 195 04 484 C1.

This device comprises an annular overdrill head embracing a cable. Nozzles for the expulsion of rinsing fluid are - when regarded in the forward driving direction - positioned at the front portion of the overdrill head. The overdrill head is pushed through the soil by rods moving it along the cable. The rods themselves are driven laterally to the cable. For the incorporation offs fastening element for the rod, the overdrill head possesses a thickening of its annular cross-section. This thickening leads to an enlarged zone of friction' obstructing the overdrill head's advance. In order to allow an improved rins-

ing effect in the soil, a greater number of nozzles is provided in the region of the thickening than in the remaining parts of smaller diameter. This leads to an increased ejection of rinsing fluid. As a general disadvantage of this method, the application of rinsing fluid does not allow to remove harder ele-

ments in the region surrounding the cable to be laid bare. Thus, the cable cannot be exposed completely leading to impediments when pushing or pulling out the cable.

- 2 With respect to this technical background, the invention has the objective to

improve the propulsion of the overdrill head.

This objective is achieved by the invention according to the independent claims. Favourable embodiments are subject of the dependent claims.

According to the invention, the area surrounding the cable to be exchanged is exposed (mechanically) with at least one moved tool being provided as a part of the overdrill head. In contrast to the exposure by applying rinsing fluid, optimised free spaces created by the tools' movement, in particular by oscillation or rotation, are achieved. Particularly a milling oscillation and rota-

tion of a tool being positioned at the overdrill head's front side allows the demolition even of hard elements in the surroundings of the conduit. These may be hard rocks, but also sockets fixed at the conduit's circumference or side conduits feeding into the conduit.

A tool according to the invention being provided as a movable part of the overdrill head may be realised by a tool corresponding to a geometrical form of an advancing means, like e.g. a boring bit provided on the overdrill head in the region in front of the fastening element for an advancing means and being directed towards the forward driving direction. independently from the removal of soil surrounding the old conduit, this permits - in the vicinity of the cable - the creation of a free space for the advancing means foliowng the overdrill head. This free space prevents or reduces the advancing mean's contact with the surrounding soil and reduces the friction to be overcome for the overdrill head's propulsion.

The overdrill head favourably is designed such that it completely embraces the conduit to be replaced. For this objective, it favourably has a tubular form with a ring shaped cross section. In principle, the overdrill head may also have the form of a circular arc segment. Possessing this form of design, the

soil surrounding the conduit can be removed in circular arc segments. An overdrill head formed like a circular arc segment permits a better guidance of the overdrill head along the conduit in particular when the overdrill head has to be moved along a strongly curved conduit. This characteristic can further be improved by an overdrill head having a coiled form and embracing the conduit like a coil.

A conduit in the wording of the description of this invention encompasses all

forms of longish elements, to which an overdrill head can be applied to. In particular, these elements are hollow conduits, e.g. for transporting liquids, a a.

cable or a strand of cables or conduits positioned side by side.

Rods are preferably used as advancing means. According to the field of

operation, one may also use nozzles driven by pressurised air or crawlerlike wheel driving means. The advancing means may also be designed such, that it produces propulsion by alternating clamp gripping to the conduit (the cable) and subsequently pushing away the conduit (the cable).

-. The fastening element serves to connect the advancing means to the o. ver-

drill head and thus is adjusted to the latter. Especially when using:rods, it is -

in case of a mainly linear propulsion - advantageous to have a rod fastening element being unrotatably connected to the overdrill head. In order to be able to also follow a meandering conduit, it is advantageous for thecontrol of moving direction, if the fastening element between the rod and the overdriil head is realised in the form of a hinge.

The expression "boring bit" means every element, that can produce a free space in the soil by its movement. Preferably this is an oscillating or rotating boring head. The boring bit may in particular also comprise cutting teeth, which are suitable for hard soil destruction. The boring bit is preferably con-

nected rotatably to a basic body of the overdrill head and particularly to the

- 4 fastening element. Favourably the boring bit with its boring axis is orientated towards the forward driving direction.

The part being in front of the fastening element in the forward driving direc-

tion is preferably understood to be that part in which - when a boring bit is positioned in this region - an exposure of those elements surrounding the old conduit is caused, which would obstruct the path of the advancing means and the fastening element belonging to it, when the overdrill head is advanced further along. In particular, the boring bit is designed as a solid body being positioned laterally from a basic body of the overdrill head.

Favourably the boring bit is designed as a cone, for it can then be guided through the soil more easily. Alternatively, it may also be realised as a frustum of a cone, a plate or a cylinder.

The propulsion of the overdrill head is much easier, when the overdrill head possesses a basic body and a tool fixed to the basic body. This tool can -

according to a boring machine - be moved in an oscillating or rotating fash-

ion by a driving means. The boring movement displaces the soil surrounding the conduit, destructs harder rock materials in the conduit's vicinity and cuts sockets and bypass conduits laterally connected to the main conduit. In the same manner and with a suitable guidance of the overdrill head one can evenly cut an e.g. U-formed bending of the conduit and short-circuit it by means of a drilling. As a driving means one can use e.g. a turbine drive, a screw motor according to the Moineau- principle or an electric motor. The rotation of the tool can also be actuated by a rotation of the rods, in particular if the rods rotation around its longitudinal axis is translated into a rotational movement of the front module by a gear unit. The driving means described for the tool can also be used for driving the boring bit in devices without tools.

Alternatively - in devices with boring bit and tool - one may employ for the tool and the boring bit each a separate driving means based on different operative principles.

- 5 A more steady guidance of the boring bit can be reslised, if the boring bit protrudes over the tool when regarded in the forward driving direction. Alter-

natively, the tool may also protrude over the boring bit th'us reducing the power necessary for driving the boring bit.

The advantages of laying bare the conduit to be replaced by moved elements being provided as a part of the overdrill head can also be realised in devices for trenchless replacement of conduits by means of an overdrill head possessing a basic body and a tool movably fixed to the basic body. By if.

employing such a tool driven rotatingly or oscillatingly or by percussion by means of a driving means, one can create a free space around the conduit to be replaced. In particular the tool's milling movement allows the destruction of hard elements in the conduit's neighbourhood, which cannot be removed by the application of rinsing fluid. This can e.g. be hard rock material but also may be sockets connected to the conduit's circumference or bypass-conduits feeding into the conduit to be replaced.

The tool can also be driven by a turbine. To achieve this objective, it may possess a turbine wheel being driven by a fluid. This fluid can be let out from nozles in the basic body, which are directed towards the turbine wheel of the tool. The fluid in particular can be a rinsing fluid escaping through nobles' from the tool after having passed the turbine. It may also be pressurised air, '' which is preferably led to 'tine basic body via a separate hose. Especially the use of pressurised air allows to obtain a high torque drive, since 'the pressurised air can be fed in at high pressures.

A further form of drive based on a fluid, e.g. a rinsing fluid or another fluid, can be realised in a screw motor. This motor operates according to the Moineau-principle. It can be fed by rinsing fluid, that is sprayed out at the overdrill head. Alternatively, a fluid especially adapted for driving the screw motor can be transported to the overdrill head.

i - 6 Another effective form of drive can be achieved by an electric motor. This motor can be provided within the basic body of the overdrill head. Alterna-

tively, it may be positioned outside the overdrill head, especially outside the boring, if its rotating movement is to be transferred to the tool. This can be accomplished by the advancing means, especially if this is reaiised as a pushing rod. For this aim, there are favourably provided means for translating a rotation of the pushing rod into the rotation of the tool at the overdrill head, e.g. a gear unit.

The advance of the overdrill head as well as the simple extraction of the conduit by pulling or pushing is facilitated, if the overdrill head ejects rinsing fluid along the conduit. It is of further advantage, if the overdrill head is cooled by fluid-ejection. For this purpose, the overdrill head preferably pos-

sesses nozzles for the ejection of rinsing and/or cooling fluid.

To enable a simple, soil displacing guidance of the overdrill head in both directions along the conduit and to facilitate the retreat of the overdrill head if wanted, it is advantageous if a further tool is movably connected to the basic body at the end region of the basic body opposite to the first tool. This tool can also be driven in a rotating fashion thereby producing an additional boring effect during a retreat, if the overdrill head is retreated for example after the movement from a start pit to a target pit.

In the following the invention is further explained by means of.exarnples depicted in the following drawing figures. These figures show: Fig. 1 a device according to the invention in a perspective view, Fig. 2 a second device according to the invention in a perspective view, Fix 3 a third device according to the invention in a perspective view,

- < - / Fig. 4 a fourth device according to the invention in a perspective view, and Fig. 5 a) to e): different embodiments of the tool (front module).

Fig. 1 shows an overdrill head 1 of a device for trenchless replacement of conduit 2. The overdrill head 1 consists of a basic body 3 and a tool 4 (front module). Laterally provided at the basic body 3 is a fastening element 5 for a an advancing means 6. in the forward advancing direction, a boring bit 7 is provided in the region in front of the fastening element 5. The boring bit has the form of a cone and possesses cutting blades 9.

The basic body 3 and the front module 4 possess a mostly annular cross section. In the manner of a tube they surround three conduits 2. The front module 4 is equipped with cutting blades 8.

For replacing the conduit, the overdrill head 1 is pushed over the conduits 2.

If desired, these can be tightened by a clamping device. The overdrill head 1 is advanced along the conduits 2 by the advancing means 6 designed as a.

pushing rod. A driving means not being depicted drives the.front. module to rotate around the middle length axis of overdrill head 1. By means of cutting blades 8 the front module 4 mills the vicinity of conduits 2. This vicinity is mainly composed of the surrounding soil, which can also consist of hard rock lumps or bricks. But also sockets connected to the conduits and protruding into the milling area of front module 4 or additional conduits leading laterally to the depicted conduits 2 are demolished by the milling movement. Thereby an annular free space around conduits 2 subsequently reducing friction resistance when pushing or pulling out the conduits 2 is produced. Simulta-

neously to the milling movement of front module 4 the boring bit 7 with its cutting blades 9 mills out a further free space e.g. beneath the conduits 2. in this free space the advancing means 6 is led, which follows the overdrill head

- 8 1 during forward movement. The free space reduces the friction resistance acting upon the advancing means making it possible to advance the overdrill head 1 and the advancing means 6 at low effort. After termination of the overdrill, this meaning the creation of a free space around the conduits 2, the old conduits are removed from the soil. Simultaneously, new conduits may be inserted, if these are connected to the conduits to be replaced and drawn into the earth when the old conduits are removed.

In the device depicted in Fig. 1, the boring bit 7 - when regarded in forward driving direction - is positioned at the same level as the front module 4. Fig. 2 - as well as the following figures and with employment of the same reference numbers for like elements - depicts a boring bit 7 protruding over the front module 4. This allows a more steady guidance of the overdrill head 1.

Fig. 3 shows a device similar to this seen in Fig. 2. The device depicted in Fig. 3 just comprises a further tool 10 (module), that is movably connected to the basic body 3 at the end region of the basic body opposite to the first front module 4. During retreat of the overdrill head 1 this additional module allows to demolish elements, which still or again obstruct the free space surrounding conduits 2.

Fig. 4 shows an overdrill head 1 without a boring bit 7. In this overdrill head i the fastening means 5 and the form of the front module 4 are chosen that way, that an annular free space around conduits 2 is created by the front module 4. This free space provides room for a low friction movement of fastening element 5 and the advancing means 6 adjacent to it.

In Fig. 5 alternative forms of tool 4 are shown. Thereby Fig. 5a to 5d repre-

sent front views of the respective tool 4, whereas Fig. Be shows a sideview.

Fig. 5a represents the geometric standard form of tool 4. This tool can e. g. Oscillate with velocity changes or pulsation. Fig. 5b shows a tool 4 with two

- 9 - large jaws 12, 14. Fig 5c shows a tool with an eccentric bulge 16. Fig. 5d shows a tool 4 with a tool 4 being oscillatabiy positioned on a running frame.

In Fig. be oscillation is achieved by a different level of cutting blades 8.

Claims

- 1 0 Claims:

1. Device for trenchless replacement or laying bare of conduits (2) com-

prising an overdrill head (1) with a fastening element (5) for an advancing means (6), characterized In that a tool (4; 7) is provided corresponding to the geometric design of the advancing means and/or the fastening means (5).

2. Device according to claim 1, characterized in that the fastening means (5) when regarded in forward driving direction is positioned laterally to a basic body (3) of the overdrill head (1).

3. Device according to claim 1 or 2, characterized in that the tool is developed as a boring bit (7).

4. Device according to any of the claims 1 to 3, characterised in that the overdrill head (1) comprises nozzles for the ejection of rinsing and/or cooling fluid.

5. Device according to any of the claims 1 to 4, characterized in that the overdrill head (1) comprises a basic body (3) and at least one further tool (4) being movably connected to the basic body (3).

6. Device according to claim 5, characterized in that the boring bit (7) protrudes over a tool (4) when regarded in forward driving direction.

7. Device for the trenchless replacement or laying bare of conduits (2) by means of an overdrill head (1), claracterised in that the overdrill head (1) comprises a basic body (3) and at least one tool (4) being movably connected to the basic body (3).

I: l\: - 1 1

8. Device according to any of the claims 5 to 7, characterized in that a screw motor is provided as a driving means for a rotating movement of the tool (4).

9. Device according to any of the claims 5 to 7, characterised in that a turbine is provided as a driving means for a rotating movement of the tool (4)

10. Device according to claim 9, characterized in that the turbine is air-

driven.

11. Device according to any of the claims 5 to 7, characteritsed in that an electric motor is provided as driving means for a rotating movement of the tool (4).

12. Device according to any of the claims 5 to 7 or 11, characterEsed in that a pushing rod is provided for the advance of the overdrill head (1) and that means for translating a rotation of the pushing rod into a rota-

tion of the tool (4) are provided.

13. Device according to any of the claims 5 to 12, characterized in that at least one additional tool (10) is movably connected to the:basic body (3) at the end region of the basic body (3) opposite to the fir$t,tool (4) .

14. Device according to claim 13, characterized in that the additional tool (10) is driven by the driving means of the first tool (4).

15. Method for a trenchless replacement or laying bare of conduits, in which the surroundings of a conduit are laid bare by means of an overdrill head driven by a driving means, characterized in that at least a part of the surroundings is mechanically treated.

- 12

16. Method according to claim 15, characterized in that a region of the surroundings of the conduit is treated, that corresponds to a geometric form of an advancing means (6).