GB2030261A

GB2030261A - A method and apparatus for unclogging clogged up conduits

Info

Publication number: GB2030261A
Application number: GB7929718A
Authority: GB
Original assignee: ENTREPRISES SOC GLE
Current assignee: ENTREPRISES SOC GLE
Priority date: 1978-09-15
Filing date: 1979-08-28
Publication date: 1980-04-02
Also published as: IT1121478B; IE48940B1; DK149444B; BE878439A; IE791748L; FR2435974B1; IT7968780A0; NL7906763A; DE2936487A1; DK385479A; LU81647A1; FR2435974A1; GB2030261B

Abstract

A curved conduit 5 in concrete 6 is intended to receive pre-stress cables. It is clogged by a plug 6' of concrete. The problem is to remove the plug 6' without damaging the relatively fragile wall of the conduit 5. This is done in a cycle of three steps. In a first step a chain of articulated shafts 7 convey a rotary drive from a motor 1 to a tool holder including a cutting tool 3. The shafts and the tool holder are guided in the conduit by guide-discs 9 in which they are free to rotate. A short hole of relatively small diameter is drilled in the plug, the length and the diameter being chosen as a function of the curvature of the conduit and its inside diameter to avoid piercing the conduit wall. In a second step the ring of concrete around the hole is blasted away by a jet of water. In a third step the chain is advanced (and lengthened if necessary) and the cycle repeats. <IMAGE>

Description

SPECIFICATION A method and apparatus for unclogging clogged up conduits The present invention relates to a method and to apparatus for unclogging clogged up conduits, in particular those clogged up with concrete. It applies advantageously to the case of curved conduits constituted by partially curved metal tubes for prestress cables used in civil engineering.

These conduits are embedded in concrete which can also get inside them.

Since these conduits must allow the lengths of prestress cable to pass through them, it is necessary to restore these conduits to their original state by freeing them from obstacles. To do this, up tili now, various methods have been used. A first solution consists in destroying the concrete on the outside and on the inside of the conduit in the clogged up part and replacing that part of the conduit. This solution must be excluded for reasons of strength and safety when the concrete must remain intact. Another solution consists in drilling by diamond coring; however, this solution is possible only in the case of a straight conduit and is impossible in the case of a curved conduit, since conventional tools damage the conduit when it is curved. A third solution consists in cleaning the conduit with a very high pressure flow of water.In practice, this solution can be used only in cases where clogging is only partial, because if clogging is complete, cleaning takes a very long time. A fourth solution, described in published Dutch patent application 68 04149, is to insert a chain of articulated drive shafts guided by respective guide-discs down a clogged curved conduit, to rotate a tool where the conduit is clogged. However, in that solution it is necessary for there to remain at least a small passage around the clogging plug for the tool to be used. In other words it is not applicable to the case where the conduit is completely blocked.

The method and apparatus according to the present invention mitigate these drawbacks of the prior art processes; indeed, using the invention, it is possible to unclog a conduit without great danger of damaging it, even if the conduit is curved and clogged right across its section.

The present invention provides a method of unclogging a conduit and more particularly a conduit which has curved lengths and is clogged up with solid material such as concrete, for example, the method consisting in a cycle of steps comprising a first step in which guided and articulated drilling means drill a hole in the front part of the clogging material, the hole being straight, of small diameter with respect to the diameter of the conduit and short enough for there to be no danger of piercing the wall of the conduit: and a second step in which the ring of clogging material which surrounds the hole thus formed is broken up and removed by pumping water into the conduit at very high pressure; and a third step of moving the drilling means forward to repeat the cycle of steps thereby avoiding damage to the walls of the conduit.

The present invention also provides apparatus for implementing the method described hereinabove. The apparatus comprises a rotary drill motor which, in use, remains outside the conduit for insertion into the conduit and a chain of articulated shafts connected at one end to be rotated by the motor and at the other end to rotate a tool holder, each rod and the tool holder being rotatably mounted in a guide-disc of smaller diameter than the inside diameter of the conduit, the tool holder being adapted to hold a cutting tool of diameter which is appreciably less than half the inside diameter of the conduit, and the drill motor being mounted on rails suitable for guiding the motor and chain of shafts forwardly during operation.

With reference to the accompanying drawings, an embodiment of the present invention is described by way of example. Those parts which 'are illustrated in several of the figures bear the same reference symbols in all of them.

Figure 1 is a schematic cross-section of the drilling apparatus as a whole; Figures 2 and 3 are respectively schematic cross-sections of the conduit before and after a rectilinear hole has been drilied; and Figure 4 is a schematic cross-section of the tool holder of the drilling apparatus.

Figure 1 illustrates a rotary drill motor 1, e.g. a pneumatic rotary drill motor with a power e.g. of 3 H.P. and suitable for rotating at 300 rpm. The motor 1 is disposed on rails 2 on which, during drilling, it moves over a distance of 1 5 to 20 cm.

The motor 1 rotates a tool holder 3 by means of a transmission system 4. The tool holder 3 and the transmission system 4 are inserted in the metal conduit 5 embedded in concrete 6 and blocked by a concrete plug 6t. In the example described, the metal conduit 5, constituted by weldless tubes, may have a diameter close to 10 cm and a thickness close to 2 mm. In the example, after a straight portion 1.50 m long, the conduit describes a spiral curve with a radius of 19.50 m and extending along a length of 8 to 10 m.

The transmission system 4 is constituted by components such as 7 of appropriate length to match the curves imposed, these components being constituted by shafts interconnected by universal couplings 8 and supported in the conduit by guide-discs 9 which remain stationary when the shafts rotate. The universal couplings could be replaced by flexible neoprene joints interconnecting the shafts. The guide-disc 9 can have e.g. a diameter of 85 mm, i.e. about four fifths of the inside diameter of the conduit 5. The function of the guide-disc 9 is to centre the component which bears it with respect to the conduit 5. In the case where the conduit is curved, the length of the components must be chosen so that they can occupy chords in the geometrical arc formed by the conduit. The articulated and transversely guided components thus match the curves of the conduit.The end of the tool holder 3 illustrated in greater detail in figure 4 includes a cutting tool 10 which is actuated by a shaft 11 rotating in a ball bearing 12 with respect to a support 13 which is integral with a guide-disc 14 whose diameter is, for example, 85 mm. The guide-disc 14 has the same configuration as the guide-discs 9 and meets the same requirements.

The tool holder 3 may have a housing, not shown, which surrounds it and which is designed to prevent the ingress of powdered abrasive material coming from the working face. A bearing plate 1 5 fixed in a sealed manner on the inlet of the conduit 5 includes a sealed through bushing for the component 7 of the transmission system 4 as well as a water inlet 1 6 for water at a usual pressure 4 kg/cm2 and an outlet 1 7 connected to a nylon pipe 1 8 which goes up to the head of the tool holder 3. The flow of water cools the drilling device. To do this, the nylon pipe 18 is inserted with the tool holder3 before the tool holder begins to operate. The water let into the conduit through the inlet 1 6 drives out the air through the outlet 17 until the water appears.The nylon pipe 18 is then removed and the waterfills the sheath to cool the tool 3, which is then started.

Figure 3 shows the result obtained by the drilling apparatus drilling into the concrete clogging material 6' illustrated in figure 2. A rectilinear hole 19 which is relatively short (e.g. 1 5 cm) is made without damaging the walls of the conduit 5. This result is obtained whatever the kind of conduit may be (straight or curved) and whatever the distance from the free end may be.

Once the hole 19 is made, the drilling apparatus is removed from the conduit and the cleaning device is brought into action and pumps a flow of water at very high pressure (e.g. 400 bars) with a discharge rate of 100 litres per minute. The device is known as a hydrolaser. The hydrolaser makes it possible to clean more thoroughly and to remove, in particular, the ring of clogging material which surrounds the hole 1 9.

Once the cleaning is finished, the operation starts again from the beginning and the drilling apparatus is again inserted after an extra arcticulated component of suitable length has been fixed to it.

Applications come within the field of civil engineering and relate in particular to unclogging curved conduits or more generally to drilling where the curved conduit is completely blocked with material whose consistencey is analogous to that of concrete and where it is necessary to avoid damaging the wal!s of the conduit

Claims

1. A method of unclogging a conduit and more particularly a conduit which has curved lengths and is clogged up with solid material such as concrete, for example, the method consisting in a cycle of steps comprising a first step in which guided and articulated drilling means drill a hole in the front part of the clogging material the hole being straight, of small diameter with respect to the diameter of the conduit and short enough for there to be no danger of piercing the wall of the conduit; and a second step in which the ring of clogging material which surrounds the hole thus formed is broken up and removed by pumping water into the conduit at very high pressure; and a third step of moving the drilling means forward to repeat the cycle of steps thereby avoiding damage to the walls of the conduit.

2. A method according to claim 1, wherein the diameter of said hole is appreciably less than half the inside diameter of the conduit.

3. A method according to claim 1 or 2, wherein the drilling means are cooled during the holedrilling operation by a flow of water in the conduit.

4. Apparatus for performing the method according to any preceding claim, the apparatus comprising a rotary drill motor which, in use, remains outside the conduit for insertion into the conduit and a chain of articulated shafts connected at one end to be rotated by the motor and at the other end to rotate a tool holder, each rod and the tool holder being rotatably mounted in a guide-disc of smaller diameter than the inside diameter of the conduit, the tool holder being adapted to hold a cutting tool of diameter which is appreciably less than half the inside diameter of the conduit, and the drill motor being mounted on rails suitable for guiding the motor and chain of shafts forwardly during operation.

5. Apparatus according to claim 4, wherein the diameter of the guide-disc of the tool holder is substantially equal to four fifths of the inside diameter of the conduit.

6. Apparatus according to claim 4 or 5, wherein the diameter of the guide-disc associated with the shafts of said transmission system is substantially equal to four fifths of the inside diameter of the conduit

7. Apparatus for unclogging a conduit, the apparatus being substantially as herein described with reference to,-and as illustrated in, the accompanying drawings.