GB2048340A

GB2048340A - Centering and Guidance Device for Drilling Rods

Info

Publication number: GB2048340A
Application number: GB8012720A
Authority: GB
Original assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Current assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Priority date: 1979-05-18
Filing date: 1980-04-17
Publication date: 1980-12-10
Also published as: FR2456832B1; JPS55159094A; DE2920126A1; IT8067639A0; IT8053156V0; GB2048340B; FR2456832A1; JPS5837477B2; IT1130807B

Abstract

A centering and guidance device for a drilling rod (1) comprises at least three support elements (4) arranged on one or more carrier elements (3). The support elements are constructed as closed and elastically deformable pressure cushions and means are provided for supplying a pressure medium to these cushions by suitable control means. <IMAGE>

Description

SPECIFICATION Centering and Guidance Device for Drilling Rods This invention relates to a centering and guidance device for drilling rods for earth drilling.

In earth drilling work and, in particular, in socalled slant drilling, it is necessary to centre the drilling rod within the drilling hole and to guide it during the drilling process. In known devices support elements are constructed as barrelshaped elements which are arranged, either rotatably by way of support through rollers or non-rotatably by the inter-position of a mounting, on the associated carrier element and are braced against the drilling hole wall. The drilling hole resulting from earth drilling can, in practice, not be accurately calibrated and again in particular in slant drilling and the known devices have the disadvantage that the barrel elements cannot accommodate themselves to such defective calibration of the drilling hole, in particular not during the drilling cycle, so that very often crooked drilling is the result.Also if, as with some known devices, the barrel elements are spring loaded, there always exists the danger of a deflection of the tool or the drilling rod. As a result exact centering and guidance of the drilling rod may not be accomplished by means of the known devices.

Thus, a centering and guidance device as discussed above should allow, while avoiding the indicated disadvantages, centering and guidance of the drilling rod or drilling stem accurately within the drilling hole and thereby the drilling tool, and as a result exclude, with certainty, crooked drilling. In addition, the centering and guidance device should also accomplish the desired accurate centering in loose rock.

Furthermore, the device should have a capacity to accommodate to the respective drilling hole progress and to associated unevenness.

In accordance with the present invention there is provided a centering and guidance device for a drilling rod for earth drilling comprising at least three support elements arranged so as to be circumferentially distributed and braceable between one or more carrier elements surrounding the drilling rod and the drilling hole wall and constructed as closed and elastically deformable pressure cushions which are respectively separately subject to pressure medium activation.

Such pressure cushions are able to accommodate themselves to the respective drilling hole progress and some uneveness within the drilling hole as well as also to changes in diameter so that an accurate centering and guidance of the drilling rod can be obtained.

Through the separate subjection to pressure medium of the individual pressure cushions an optional adjustment and associated centering can additionally be obtained. The drilling rod can as a result be accurately controlled in its guidance within the drilling hole, which is particularly important in slant drilling. If necessary a device in accordance with the invention can also be used in combination with a mechanical guidance arrangement for a coarse centering which is connected in series with a device in accordance with the invention. In order to accommodate changes in location, pressure changes can be induced in the pressure cushions. The pressure cushions are also seen as very simple construction parts so that as a whole the device can be constructed particularly simply. The pressure medium supply can be provided with simple media and with simple control means.A device according to the invention may ensure therefore a particularly accurate drilling result and avoid in particular crooked drilling.

A particularly preferred constructional method particularly adapted to the pressure cushions is obtained in a further embodiment of the invention in that the carrier element or elements are arranged to be supported concentrically about the drilling rod so as to be freely rotatable and longitudinally slidable with respect thereto and the pressure cushions are mounted on the periphery of the carrier element or elements.A particularly preferred embodiment of the pressure medium supply means can be obtained in a further embodiment of the invention in that a separate pressure medium line is provided for each pressure cushion for the pressure medium activation thereof which line on the one hand is connected by way of a change-over valve to a relief line common to all the pressure cushions which ends in the drilling hole and, on the other hand, is connected by way of a non-return valve to a supply line common to all the pressure cushions. As a result the pressure medium activation is able to be controlled securely in a particularly simple manner.

In order to be able to induce desired changes in the pressure medium activation, it is also possible in accordance with a further embodiment of the invention that selected pressure cushions may be connected to associated separate pressure medium supply lines.

Further characteristics details and advantages of the invention result from the claims and from the following description of an exemplary embodiment of the invention illustrated in the drawings, in which: Fig. 1 is a side view of a centering and guidance device constructed according to the invention and located within a drilling hole and with a drilling rod passed therethrough; Fig. 2 is a partial sectional view on the line A B of the device of Fig. 1; Fig. 3 is a control diagram of the pressure medium supply to the pressure cushions of the device according to Figs. 1 and 2 for drilling with liquid in the drilling hole; and Fig. 4 is a control diagram for the pressure medium supply to the pressure cushions of the device according to Fig. 1 and 2 for drilling with only air in the drilling hole.

In Figures 1 and 2 a centering and guidance device according to the invention is illustrated schematically as far as possible with only those parts which serve to explain the invention.

The device serves to centre and guide the schematically illustrated drilling rod 1, which can also be a drilling stem, in the drilling hole 2. A carrier element 3 which, for example consists of two annular cylindrical parts 3a and 3b which are connected with each other through radial ties 3c, concentrically encloses the drilling rod 1. On the outer periphery of the carrier element 3, here the radially outer cylindrical part 3b, are held, in a suitable manner and distributed about the periphery, closed and elastically deformable pressure cushions 4. These pressure cushions are constructed from suitable resistant rubber elastic material and conform as far as possible to the concentric form as shown particularly in Figure 2.

The connection of the pressure cushions with the periphery of the cylinder 3b of the carrier element 3 is obtained, e.g. through a suitable adhesive process. The carrier element 3 is supported by its inner cylinder 3a both freely rotatably and longitudinally slidably concentrically about the drilling rod 1.

The pressure cushions 4 are respectively separately subject to pressure medium activation.

In Fig. 2 connection stubs 5 serving to this end are illustrated. Figure 1 shows in the same schematic way a common supply line 6 for the pressure medium activation of the pressure cushions 4. Figs. 3 and 4 show two embodiments of controls for the pressure medium activation of the pressure cushions 4 of the centering and guidance device illustrated in Figs. 1 and 2.

Initially the arrangement of Fig. 3 is described and this is used for a pressure medium supply of the pressure cushions in the case of a drilling with liquid in the drilling hole. Pressurised air is used as the pressure medium.

Above ground at a suitable location are arranged a pressurised air compressor 7 and a main valve 8 as well as an exhaust line 9 to the atmosphere and finally the common supply line 6, the supply line 6 being led into the drilling hole.

The main valve 8 is shown as a multi-way valve with three connections and three control positions. The illustrated middle control position represents the neutral position. The common supply line 6 is led by way of a non-return valve 10 to separate individual supply lines 11 which are connected for their part to the pressure cushions 4, in each case by way of an associated non-return valve 12. Each individual supply line 11 is furthermore connected by way of a respective change-over valve 13, activated from the supply line 6, to an outlet line 14 which is common to all the pressure cushions which ends by way of a non-return valve 1 5 in the drilling hole above the pressure cushions 4.

With the help of this control the device is operated as follows: The main valve 8 is set to its lower control position so that the compressor 7 therefore supplies the pressure cushion 4 with pressurised air by way of the common supply line 6 and the individual supply lines 1 Thus the change of the change-over valves 1 3 to the upper closed position (not illustrated) occurs. Once the pressure cushions are activated in the desired manner, the main valve 8 is set back to the neutral position illustrated in the drawing and is therefore closed. If the pressure cushions 4 are to be unloaded, then initially the main valve 8 is set for a short time in its upper control position and is therefore connected for a short while to the atmosphere exhaust line 9.As a result a changeover of the change-over valves 1 3 into the open position (illustrated) occurs and they can release the pressurised air from the pressure cushions 4 by way of the change-over valves 1 3 and the common exhaust line 14 over the non-return valve 1 5 into the drilling hole. It might be noted here that through this control the common supply line 6 can have a minimal cross-section. The respective activation or unloading of the pressure cushions can be obtained with the described and illustrated device in a respective desired degree through the described measures.

Fig. 4 shows a control for the use of the centering and guidance device according to the invention in drill working in which only air is present in the hole. In Figure 4 those parts of the control which correspond to the same parts in Figure 3 are indicated with the same reference numerals and are not described again here. In this embodiment of the device a change-over valve 16 and an injector 17 are set in between the compressor 7 and the main valve 8 and are connected to the respective connections of the control valve 1 6 and the main valve 8 as illustrated in Fig. 4. The pressure medium activation of the pressure cushions 4 occurs in the manner already described with reference to Fig. 3.

The unloading differs however from that described with reference to Fig. 3. For unloading, initially the main valve is set to its upper control position so that over-pressure can be released to the atmosphere in the drilling hole by way of the common relief line 14 and the non-return valve 1 5. The pressure cushions are not however completely collapsed because of the lack of the liquid pressure still prevailing as in the case of the Fig. 3 arrangement, so that the device cannot be withdrawn. Accordingly the compressor is set on to the injector 1 7 by way of the change-over valve 16 and in particular in the described upper position of the main valve 8. In this position the injector sucks further pressurised air out of the pressure cushions 4 so that the pressure cushions are drawn together in the desired manner and the device can then be withdrawn. The suction occurs by way of a suction line 18 (shown dashed) with a non-return valve 1 9.

The devices illustrated in Figs. 3 and 4 are only exemplary embodiments which are advantageous for the described use. Nevertheless it is also possible through simple control technique measures to connect determined desired pressure cushions to respective separate pressure medium lines in order to be able to provide location corrections through different pressure medium activation. Unloading can then be obtained in a similar manner to that described with reference to Figs. 3 and 4.

Claims

1. A centering and guidance device for a drilling rod for earth drilling comprising at least three support elements arranged so as to be circumferentially distributed and braceable between one or more carrier elements surrounding the drilling rod and the drilling hole wall and constructed as closed and elastically deformable pressure cushions which are respectively separately subject to pressure medium activation.

2. A device according to claim 1, wherein the carrier element or elements are arranged to be supported concentrically about the drilling rod so as to be freely rotatable and longitudinally slidable with respect thereto and the pressure cushions are mounted on the periphery of the carrier element or elements.

3. A device according to claim 1 or claim 2 wherein, for pressurisation by the pressure medium, a separate medium line is provided for each pressure cushion which, on the one hand, is connected by way of a change-over valve to a relief line common to all the pressure cushions which ends in the drilling hole, and on the other hand, is connected by way of a non-return valve to a supply line common to all the pressure cushions.

4. A device according to any one of the preceding claims wherein selected pressure cushions may be connected to associated separate pressure medium supply lines.

5. A centering and guidance device substantially as hereinbefore described with reference to Figs. 1 to 3 or to Figs. 1, 2 and 4 of the accompanying drawings.