AU6825600A

AU6825600A - Cutting head

Info

Publication number: AU6825600A
Application number: AU68256/00A
Authority: AU
Inventors: Franz-Josef Puttmann
Original assignee: Tracto Technik GmbH and Co KG
Current assignee: Tracto Technik GmbH and Co KG
Priority date: 1999-07-21
Filing date: 2000-07-20
Publication date: 2001-02-13
Also published as: WO2001007822A1; DE29912676U1; EP1203183A1

Description

WO 01/07822 PCT/EPOO/06953 "Cutting head" The invention relates to a cutting head for bursting, in particular for longitudinally splitting, 5 pipelines laid in the earth and for simultaneously drawing in at least one new line, for example a pipeline and/or lines serving to transmit electrical energy and/or data, and claims the priority of German Utility Model 299 12 676, the contents of which are 10 referred to. In practice, it is often necessary to replace pipelines laid in the earth, for example for fresh or waste water, with a new pipeline. Used in this case are self-propelled and/or pulled devices which are equipped 15 with tools for bursting the old pipeline (old line). This may be done by means of a ram boring device which has been disclosed by British Laid-open Specification 2 138 522 and whose percussion tip is provided with lateral, pivotably mounted blades pointing outward. The 20 cutting edges of these blades run at an acute angle to the percussion tip and move radially outward under the effect of a conical percussion pin advanced by the percussion piston of the ram boring device, so that the pipe wall is shattered under the effect of forces 25 acting radially outward, while the likewise conical body of the shattering head at the same time pushes the fragments of the old pipe and the surrounding earth outward. European Patent 0 731 252 describes a device which 30 has a similar action, but in which the tip of the ram boring device is provided with a separate shattering head. This shattering head has cutting edges which are distributed over its periphery and are fixed to the housing, and the envelope circle of which forms a cone 35 which becomes larger against the direction of advance. CONFIRMATION COPY - 2 The cutting edges likewise burst the old pipe with a force component directed radially outward. In the case of shattering or cutting devices acting outward in this way or in a similar way, the 5 bursting of the old pipe and the expanding of the earth take place by means of the cutting edges or also by means of rotating cutter disks against the earth, which usually tightly encloses the old pipe and is more or less provided with stones and other ground obstacles. 10 This requires high pushing and/or driving forces, since the shattering and/or cutting force bursting the old pipe is applied and the deformation resistance of the earth surrounding the old pipe is to be overcome more or less at the same time. 15 In addition, in the case of pipelines made of tougher materials, there is the risk of the old line expanding in the region of the cutting edges, at least to begin with, and consequently of the deformation resistance of the pipe material still having to be 20 overcome. The problem underlying the invention is therefore to provide a means of bursting buried pipelines which needs only a relatively small expenditure of force and is in addition distinguished by a simple construction. 25 To solve this problem, the invention proposes the use of a cutting head having a guide which is provided with at least one hook-shaped blade. The guide may consist of a conventional ram boring device, as described in German Patent 195 30 972 or US Patent 5 30 960 892. In addition or alternatively, a suitable guide is also a pin which is provided on the outside with preferably two hook-shaped blades opposite one another. The guide pin projects in situ into the old pipe and in the process automatically positions the hook 35 shaped blades with regard to the pipe in such a way - 3 that they come fully into effect. Such hook-shaped blades, like a load hook, have a jaw which is defined on the outside by a cutting edge and on the inside by the guide pin. Since the jaw opens in the direction of 5 that part of the pipeline which has still not been burst, the old pipe engages in the cutting jaw and is burst with an inwardly directed force component as a result of the profile of the cutting edge. Since the cutting hooks or cutting edges have a 10 very small cross section transversely to the direction of advance and the guide pin moves loosely or without wall friction through the old pipe, because the cutting head is automatically centered when there are a plurality of hook-shaped blades, the expenditure of 15 force during the bursting of the old line is relatively small. The guide pin may have an aperture which extends in the longitudinal direction and is intended for accommodating a driven pushing and/or pulling rod 20 system, for example consisting of ladder-like sections coupled via a push-fit connection, and may also have a conical point facilitating the insertion into the old pipe. In order to releasably connect the cutting head to 25 the rod system, the guide pin has a coupling which may be designed as a rotary bearing. The rotary bearing prevents canting of the rod system under the effect of transverse forces acting on the cutting head. 30 When using a pulling or pushing rod system, the guide pin is not essential if the hook-shaped blade is provided with a base which engages in an opening or a passage in the rod system. An essentially rigid connection between the hook-shaped blade and the rod 35 system is obtained if the base engages in the rod- - 4 system opening in a positive-locking manner; it may be additionally locked there. The cutting head may also be connected via the rod system to an expanding body which follows the cutting 5 head at a distance and pushes the fragments of the old pipe which remain after the cutting - or, in the case of plastic pipes, the pipe-wall strips - and the surrounding earth radially outward. This results in a new earth passage having a greater width compared with 10 the outside diameter of the old pipe, into which earth passage a new pipe and/or a bundle consisting of a plurality of lines for the transport of fluid media and/or for the transmission of data and/or electrical energy and/or empty pipes can be drawn by means of the 15 expanding body. The invention is described in more detail below with reference to exemplary embodiments shown in the drawing, in which: Fig. 1 shows a drawing head with an expanding body 20 in situ, Fig. 2 shows a cross section through the drawing head along line II-II in fig. 1, Fig. 3 shows an enlarged representation of a cutting jaw, 25 Fig. 4 shows the side view of an old pipe with a cutting head in the situation in fig. 1, Fig. 5 shows a rod system with a hook-shaped blade without guide pin, and Fig. 6 shows a plan view of the rod system in the 30 radial direction. Extending through an old pipe 2 of plastic laid in the ground 1 is a rod system 5 consisting of individual sections 4 which are each connected to one another by a push-fit connection 3. The rod system is connected to a 35 pulling and pushing drive (not shown) and moves a cutting head 6 and an expanding body 7 through the old - 5 pipe 2 or the ground 1. The cutting head 6 is releasably connected to the rod system 5 via a rotary coupling 8. The cutting head 6 consists of a guide 9, 5 projecting into the old pipe 2 and a having a conical entry portion 10, and of a longitudinal passage 11 accommodating the rod system. On the outside, the guide 9 is provided with four hook-shaped blades 12, in whose jaw 12 that part of the old pipe 2 which has still not 10 been burst projects. The jaw 13 is defined on the outside by a cutting edge 14 and on the inside by the guide 9. The profile of the cutting edges 14 causes them to act inward, i.e. in the direction of the guide, during the longitudinal splitting of the old pipe 2. 15 During the forward movement of the cutting head 6 (to the right in fig. 1), the wall of the old pipe 2 made of plastic is split into four longitudinal strips 15 which the expanding body presses outward together with the surrounding earth 1. 20 The expanding body consists of a conical point 16 and a cylindrical guide piece 17 with a connection (not shown in detail) for a new pipeline 18 having a larger diameter than the old pipe 2 and a connection for a further line 19. 25 A new pipeline of smaller diameter may also take the place of the new pipeline 18, this new pipeline of smaller diameter then being surrounded by a larger annular space 20, through which further pipelines, empty pipes and/or transmission lines can be drawn into 30 the earth in a trenchless manner by means of appropriate connections at the guide piece 17. It can be seen from the sectional representation in fig. 2 that only a very small part of the cutting head, namely only the outer ends of the hook-shaped 35 blades 12, comes into contact with the earth. The earth friction to be overcome is correspondingly low during - 6 the longitudinal slitting or shattering of the old pipe. At the same time, the representation illustrates the low constructional outlay for the cutting head and, in combination with the representation in fig. 1, its 5 stable position during the bursting of the old pipe 2. The hook-shaped blade 21 shown in figs 5, 6 has a base 22 with a stop plate 23 and two cutting edges 14. The base 22 engages in one of the apertures 24 of the rod system 5 in a positive-locking manner and is locked 10 there by means of a releasable plate 25. This results in a rigid connection between the rod system 5 and the cutting head; the rod system in this case serves as a guide for the hook-shaped blades 21.

Claims

1. A cutting head for bursting pipelines (2) laid in the earth, having a guide (5, 9) which is provided with 5 at least one hook-shaped blade (12, 21).

2. The cutting head as claimed in claim 1, characterized in that the hook-shaped blade (12) is connected to a guide pin (9).

3. The cutting head as claimed in claim 2, 10 characterized by a guide pin (9) provided with an aperture (11) extending in the longitudinal direction.

4. The cutting head as claimed in claim 2 or 3, characterized in that the guide pin (9) has a conical point (10). 15

5. The cutting head as claimed in one of claims 2 to 4, characterized in that the guide pin (9) is connected to a coupling (8).

6. The cutting head as claimed in claim 5, characterized in that the coupling is designed as a 20 rotary bearing (8).

7. The cutting head as claimed in claim 5 or 6, characterized in that the guide pin (9) is connected via the coupling (8) to a driven rod system (5).

8. The cutting head as claimed in claim 1, 25 characterized in that the guide consists of a rod system (5) provided with at least one insertion opening (24), and a base (22) of the hook-shaped blade (21) engages in the insertion opening.

9. The cutting head as claimed in claim 8, 30 characterized in that the base (22) is locked in the insertion opening (24).

10. The cutting head as claimed in one of claims 7 to 9, characterized in that the rod system (5) consists of individual rod-system sections (4) releasably connected 35 to one another via a push-fit connection (3). - 8

11. The cutting head as claimed in one of claims 7 to 10, characterized in that the hook-shaped blade (12) is connected to an expanding body (16, 17) via the rod system (5).