GB2226379A

GB2226379A - A washing pipe connection for a wash drilling string

Info

Publication number: GB2226379A
Application number: GB8928219A
Authority: GB
Inventors: Ernst Hoffmann
Original assignee: Schmidt & Co Kranz GmbH
Current assignee: Schmidt & Co Kranz GmbH
Priority date: 1988-12-15
Filing date: 1989-12-13
Publication date: 1990-06-27
Also published as: IT8948622A0; JPH02204593A; GB8928219D0; DE3844225C1; ES2017435A6; FR2640679A1; IT1237228B

Description

1 -I- PATENTS ACT 1977 Agents' Reference: P6073GB-H/JCC/ac

DESCRIPTION OF INVENTION

Title: "A washing pipe for a wash drilling string" THIS INVENTION relates to a washing pipe for a wash drilling string provided at one end with a plug formed with a longitudinal duct and with sealing means and with a transversely extending locking pin radially movable by spring force, and provided at the other end with a insertion end and co-operating sealing means matching the plug of another washing pipe and also provided with a transverse bore for receiving the locking pin of the other washing pipe. Such a washing pipe is herein referred to as being "of the kind specified".

In DE-GM 1919112 it is proposed to use a longitudinally extending leaf spring for radially moving the locking pin. In the initial state, the leaf spring is T-shaped. A short double-armed transverse web is attached to one end of the long spring tongue and is rounded to form a clamping sleeve. The length of the clamping sleeve measured around the outer periphery is made such that it matches the inner contour of the plug. However, the end faces of the clamping sleeve are at a distance from one another. They thus form a relatively wide gap in which, in the assembled state, a retaining pin engages and is looked in the wall of the plug. In this manner the leaf spring is secured in the longitudinal duct of the plug.

The sealing means between two adjacent washing pipes comprise the end face of the plug and a sealing sleeve inside the insertion end and abutting the end face. This kind of seal, however, is inadequate at great depths and/or in long and deep drill holes.

The invention is based on the problem of developing a washing pipe of the kind specified so as to improve the seal between two washing pipes inserted into one another, reduce the resistance encountered by the washing water in the individual coupled washing pipes, increase the moment of resistance of the leaf spring, and facilitate assembly of the leaf spring inside the longitudinal duct.

According to the invention, there is provided a washing pipe for a wash drilling string provided at one end with a plug formed with a longitudinal duct and with sealing means and with a transversely extending looking pin radially movable by spring force, and provided at the other end with an insertion end and co-operating sealing means matching the plug of another washing pipe and also provided with a transverse bore for receiving the locking pin of the other washing pipe characterised by the following features in combination:

(a) a longitudinally extending spring element is secured in the longitudinal duct of the plug and has an end portion abutting the inner end face of the locking pin and (b) a sealing ring embedded in an annular groove is provided at the free end of the plug and a peripheral sealing surface is provided at the inner end of the insertion end.

A slim spring element incorporated in the longitudinal direction in the longitudinal duct, in combination with radially acting sealing means on the plug and on the insertion end, ensures that the higher water pressures necessary at greater depths are reliably controlled without offering greater resistance to the washing water.

On the other hand, owing to the low resistance to the water in the area where two washing tubes are coupled, a pump is frequently unnecessary even in long and deep drill holes.

The spring element can be made of spring wire or can be a leaf spring. It can be secured in the longitudinal duct by riveting or welding or friction or adhesive.

In an advantageous embodiment of the invention the clamping sleeve provided at the end of a leaf spring is specifically matched to the curvature of the longitudinal duct. The length of the clamping sleeve around its outer periphery is made such that, as a result of the predetermined difference in diameter between the longitudinal duct and the clamping sleeve, the sleeve is secured in the longitudinal duct without any additional securing means. The shape of the clamping sleeve, in conjunction with the spring tongue attached thereto, also increases the resistance to bending.

Preferably the leaf spring has a spring tongue which tapers trapezoidally in width towards its free end, as viewed radially with respect to the longitudinal axis of said sleeve-like end portion and is curved, in crosssection, perpendicular to said longitudinal axis, to match the curvature of the longitudinal duct.

Owing to the slim trapezoidal shape of the spring tongue, the leaf spring has a greater moment of resistance to bending, so that it remains undamaged after frequent coupling or uncoupling processes even under prolonged exposure to corrosive washing liquors. Another result of matching the tongue cross-section to the curvature of the duct wall along the entire length of the spring tongue is to increase the moment of resistance to bending and also to obtain a maximum internal duct crosssection.

Preferably the peripheral extent of the spring tongue in the region of its junction with the clamping sleeve is approximately equal to half the circumference of the clamping sleeve, whereas the width at the free end of the spring tongue is made approximately equal to half the diameter of the clamping sleeve. These features additionally increase the moment of resistance of the leaf spring.

Preferably the spring tongue has a bent free end, the length of which matches the size of the inner end face of the locking pin, to obtain very close-fitting contact between it and the spring tongue.

The leaf spring can be clamped in the longitudinal duct of the plug by means of a tongue extending towards the longitudinal centre of the washing pipe or by means of a tongue extending towards the end face of the plug.

Depending on how the leaf spring is installed, it is then possible to vary the length of the longitudinal portion of the plug which has a round outer cross-section. If the leaf spring is installed so that its tongue extends towards the end face of the washing pipe, the outer longitudinal portion having a round outer cross-section can be relatively short. If on the other hand the leaf spring is installed with the tongue extending towards the longitudinal centre of the washing pipe, the outer longitudinal portion of the plug having a round cross-section can be made longer. In the case of the last-mentioned washing pipe, the sealing region between two coupled washing pipes can also be moved more deeply into the insertion end.

Embodiments of the invention are described below by way of example with reference to the accompanying drawings, in which:

FIGURE 1 is a side view, partly in vertical longitudinal section, of the plug end region of a washing pipe for a wash drilling string; 1 1 FIGURE 2 shows the insertion end of the washing pipe of Figure 1, likewise in side view and partly in vertical longitudinal section; FIGURE 3 is a vertical cross-section through the washing pipe in Figure 1 along line III-III; FIGURE 4 is a vertical cross-section through the washing pipe in Figure 1 along line IV-IV; FIGURE 5 is a side view of a leaf spring for the washing pipe in Figures 1 to 4; FIGURE 6 is a plan view of the leaf spring in Figure 5; FIGURE 7 is an end view of the leaf spring in Figure 5 along arrow VII; FIGURE 8 is a side view, partly in vertical longitudinal section, of the plug end region of a washing tube for a wash drilling string according to another embodiment; FIGURE 9 is a side view of the insertion end of the washing pipe in Figure 8; FIGURE 10 is a vertical cross section through the washing pipe in Figure 8 along line X-X and FIGURE 11 is a vertical cross-section through the washing pipe in Figure 8 along line XI-M Figures 1 and 2 show a washing pipe 1 for a wash drilling string. A washing pipe 1 is combined with other identical washing pipes 1 to form a wash drilling string for drilling holes in underground working or in tunnelling. Holes up to 200 m deep can be drilled by this method. The C washing pipe 1 has a central pipe 2 having a peripheral helix 3. The end faces 4 of helix 3 end in the vertical longitudinal central plane of the central pipe 2 and on the same side thereof.

The central pipe 2 is circular on the inside and outside over most of its length. At both ends, however, the pipe 2 has, both internally and externally, the crosssectional shape of a square with rounded corners (see Figure.4). In principle, the end of the pipe could have any noncircular shape and, in the following description, the interior of one end of the pipe is refered to as the inner polygon 5.

A plug 6 having a longitudinal duct 7 therethrough (in the form of a cylindrical axial bore) is inserted into the inner polygon 5 at said one end (Figure 1). The part of the plug member 6 fitted in the inner polygon has, externally, a cross-sectional shape exactly matching the crosssectional shape of te inner polygon and thus fits closely within the inner polygon. The plug member 6 is rigidly fixed in the pipe 2, for example by welding. A major part of the plug member 6 projects from the end of pipe 2 and the part is divided into two longitudinal portions A and B, the portion A nearer the central pipe 2 being given a polygonal outer cross-section, whereas the other longitudinal portion B is given a round outer cross-section (Figure 3). The axial length of the two longitudinal portions A and B is made approximately equal. Preferably, of course, the portion A simply has the same cross-sectional shape as the portion engaged in the inner polygon and is merely a longitudinal extension of the latter portion.

A seal in the form of an 101 ring 10 is received in an annular groove 9 at the end of the round-section longitudinal portion B. 1 A looking pin 12 is disposed so as to be transversely movable in a correspondingly shaped insert 11, a short distance before the transition region from the polygonal longitudinal portion A to the round longitudinal portion B. The locking pin 12 has a locating plate 13 in the longitudinal duct 7 of the plug 6, the diameter of plate 13 being greater than the diameter of pin 12. Between plate 13 and the inner wall of insert 11, the pin 12 is surrounded by an 101 ring 14 for sealing purposes.

The locking pin 12 is continuously urged radially outwards by a leaf spring 15. As shown in this connection by Figures 1, 3 and 5 - 7, the leaf spring 15 comprises a spring tongue 17 and a sleeve-like end portion 16 matching the contour of the longitudinal duct 7 and having a longitudinal slot extending therealong. Sleeve 16 and tongue 17 are in one piece. The circumference of sleeve 16 in the unstressed state of the sleeve portion 16 is made slightly greater than the internal peripheral extent of the longitudinal duct 7. In the non-assembled, unstressed state, there is a significant gap between the edges 18 of sleeve 16 on opposite sides of the slot (Figure 7). That is to say, the slot is of significant width in the unstressed state of the sleeve 16. Consequently the sleeve 16 must be compressed somewhat,, against the resilience of the spring material of the sleeve, (thereby narrowing the gap between the edges 18) to fit within the duct 7 and is thereafter pressed firmly against the wall of duct 7 by its own resilience, to hold the spring firmly in place.

In the embodiment illustrated, the duct 7 is in the form of a circular bore and the sleeve 16 'is of arcuate cross-sectional form.

The spring tongue 17 is made trapezoidal as viewed in Figure 6, i.e. as viewed perpendicular to its direction of greatest transverse extent and its cross-section is arcuate c and matched to the curvature of the longitudinal duct 7 (Figure 3). The width of tongue 172 measured circumferentially, in the transition region adjoining the clamping sleeve 16, is about equal to half the circumferential extent of the clamping sleeve 16, whereas the width at the free end of the spring tongue 17 is about equal to half the diameter of the clamping sleeve 16.

Also, as shown particularly in Figures 5 and 7, the free end 20 of the spring tongue adjacent the inner end face 19 of the locking pin 12 is bent radially outwards, thus ensuring a close-fitting abutment between tongue 17 and plate 13.

In the embodiment in Figure 1, the clamping sleeve 16 is secured by clamping in the longitudinal portion of the longitudinal duct 7 adjacent the end face 21 of the plug 6.

The opposite end of the washing pipe from that bearing the plug 6, which opposite end is referenced 22 in Figure 3, is adapted to receive the plug 6 of an adjoining washing pipe when a series of such pipes is connected end to end to form a drill string.

The insertion end 22 of the washing pipe 1, as shown in Figure 2, has an internal polygonal contour 23 which matches the external contour of the polygonal longitudinal portion A of the plug 6 and corresponds to the inner polygon 5 on the end near the plug. The polygonal contour 23 is adjacent a cylindrical transition region 24 which serves as a sealing surface for each pair of coupled washing pipes 1, in cooperation with the sealing ring 10 at the end of plug 6. A recess 27 formed in the wall 26 of the insertion end 22 cooperates with the locking pin 12 of another washing pipe 1.

Figures 8 to 11 show a variant embodiment, parts in Figures 8 to 11 which are identical with parts in Figures 1 to 4 having the same references and parts which correspond with parts in Figures 1 to 4, but are not identical having the same reference with the added "I" marking. Washing pipe 1. 1 of Figures 8 to 11 is very similar as regards its construction to the embodiment of Figures 1 to 4 and so will not be described in detail except insofar as it differs from the embodiment of Figures 1 to 4.

One difference is that the longitudinal portion B' of plug 61, which has a round outer cross-section, in only about half as long as the polygonal longitudinal portion A'. There are corresponding differences as regards the length of the polygonal contour 231 and the cylindrical contour 241 at the insertion end 221 of the washing pipe 11.

Another difference is that in the arrangement of Figures 8 to 11, the leaf spring 15 has its sleeve 1'6 secured in the inner longitudinal portion 25 of the longitudinal duct 7, so that the spring tongue 17 points towards the end face 21 of the plug 61 rather than in the Figures 1 to 4. The construction identical with that in Figures 5 to opposite direction as in of the leaf spring 15 is 7.

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Claims

1. A washing pipe for a wash drilling string provided at one end with a plug formed with a longitudinal duct and with sealing means and with a transversely extending looking pin radially movable by spring force, and provided at the other end with an insertion end and co-operating sealing means matching the plug of another washing pipe and also provided with a transverse bore for receiving the locking pin of the other washing pipe characterised by the following features in combination:

(a) a longitudinally extending spring element (15) is secured in the longitudinal duct (7) of the plug (6, 61) and has an end portion (17) abutting the inner end face (19) of the locking pin (12), and (b) a sealing ring (10) embedded in an annular groove (9) is provided at the free end of the plug and a peripheral sealing surface (24, 241) is provided at the inner end of the insertion end (22, 221).

2. A washing pipe according to claim 1, characterised in that the spring element is a leaf spring (15) and has a slotted sleeve-like end portion (16) matching the contour of the longitudinal duct (7) and located as a force-fit in the longitudinal duct (7).

A washing pipe according to claim 2, characterised in that the leaf spring has a spring tongue which tapers trapezoidally in width towards its free end, as viewed radially with respect to the longitudinal axis of said sleeve like end portion, and is curved, in cross-section perpendicular to said longitudinal axis, to match the curvature of the longitudinal duct (7).

4. A washing pipe according to claim 2 or claim 3, characterised in that the peripheral extent of the spring 1 c tongue (17) in the region of its junction with the clamping sleeve (16), is approximately equal to half the circumference of the clamping sleeve (16), whereas the width at the free end (20) of the spring tongue (17) is made approximately equal to half the diameter of the clamping sleeve (16).

A washing pipe according to any of claims 2 to 4, characterised in that the free end (20) of the spring tongue (17) abutting the inner end face (19) of the locking pin (12) is bent radially outwards.

A washing pipe according to any of claims 2 to 5, characterised in that the clamping sleeve (16) is secured between the locking pin (12) and the inner end of the plug (61).

A washing pipe according to any of claims 2 to 5, characterised in that the clamping sleeve (16) is secured in the region of the longitudinal duct (7) adjacent the end face (21) of the plug (6).

8. A washing pipe according to any of claims 1 to 6, comprising a central pipe, said plug being provided by a plug member inserted into the central pipe and projecting therefrom beyond an end face of the central pipe, the part of said plug member projecting from the central pipe including an inner longitudinal portion, nearer the central pipe, which is externally polygonal in cross-section and further including an outer longitudinal portion, further from the central pipe, which is round in outer crosssection, the length of the outer longitudinal portion (B) being approximately equal to the length of the inner longitudinal portion (A).

9. A washing pipe according to any of claims 1 to 5 or 7, comprising a central pipe, said plug being provided by a plug member inserted into the central pipe and the part of said plug member projecting from the central pipe including an inner longitudinal portion nearer the central pipe, which is externally polygonal in cross- section and further including an outer longitudinal portion further from the central pipe, which is round in outer cross-section, characterised in that the outer longitudinal portion (P) is made about half as long as the inner longitudinal portion (M).

10. A washing pipe, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 7 of the accompanying drawings.

11. A washing pipe, substantially as hereinbefore described with reference to, and as shown in, Figures 8 to 11 of the accompanying drawings.

12. Any novel feature or combination of features described herein.

PublishedJ990atThe Patent Office. StateHouse 66 71 High Icborn. LcondonWCIR47P Further copies niky be obtained from The PatentOfficc Sales Branch. St Mazy Cray. Orpington. Kent BR-1 3F.r P.-inted by Mu:t:. I"--% techniques ltd. St Mary Cray. Ken. Cc.-. 1 87,