GB2223706A - Arrangement for cleaning a lance head - Google Patents

Description

1 Aú.úAnatlent for Cleaninq a Lance Head -- -------- - ----- 2 22 3 7 0 6

The invention relates to an arrangement for cleaning the contact -rodbear ing lance head of a lance to be introduced into a metallurgical vessel, in particular a lance carrying a measuring and/or sampling probe, which arrangement comprises a milling head being in contact with the lance head during the cleaning procedure, which milling head is capable of being placed into a position in alignment with the lance head and lifted and lowered relative to the lance head and the contact rod receivingthe measuring and/or sampling probe.

From DE-C - 23 64 911, an arrangement for cleaning the end of a blowing lance is known, wherein the blowing lance is surruunded by a hollow body constituting the cleaning head and being rigidly arranged, in which hollow body fingers are fastened which contact the surface of the blowing lance and effect the cleaning thereof. By lifting the lance after the blowing procedure, the cylindrical surface of the blowing lance is slided along the fingers, thus being cleaned.

An arrangement of this type suffers the disadvantage that the rigidly arranged cleaning head is exposed to the emissions and the thermal radiation emanating from the metallurgical vessel. Furthermore, this known arrangement is s u i t e d to clean cylindrical surfaces of a lance only, whereas the front-side end surface of the blowing lance cannot be cleaned.

A particular problem is faced with lances carrying measuring and/or sampling probes, whose lance head immerses into a slag layer during the sampling or measuring procedures. Such lances, as are used, for instance, to detect temperature and 2 carbon-content values in steel melts, operate with one-way probes, which are slipped on a contact rod projecting from the end side of the lance and drawn off the contact rod after having carried out a measurement, i. e., a f t e r immersion into the steel melt. In doing so, the formation of incrustations of slag and metal on the external and front sides of the lance is unavoidable. In some cases, e.g., with badly accommodated probes, slag or metal may enter between the front face of the lance and the front face of the probe contacting this front face. Such incrustations, unless removed, may impair the accurate contact of the measuring wires between the probe and the contact rod when a new probe is slipped on, which may lead to faulty measurements.

From AT-B - 381 795, an arrangement of the initially defined kind is known, which comprises a dividedly designed cleaning head on whose upper side the milling head is arranged. The cleaning head, via arms, is placed on a support liftably and lowerably mounted on vertical guides on the cantilevering end of a carrier. With this known arrangement, the milling head is capable of being set into movement by means of a pressure the support on one end and, via a rods, to the cleaning head on the lowering movements of the milling a reciprocating rotational medium cylinder hinged to double arm and articulated other end. The lifting and head are effected by means of a pressure medium cylinder arranged on the cantilevering end of the carrier, allowing for lifting and lowering of the support. In order to centrically seize the contact rod during pivoting into the operation position, the divided casing of the cleaning head comprises tong-like centering projections. To guide the cleaning head on the contact rod of the lance, guiding surfaces formed by half a circularlyring-shaped plate as well as adjustment screws adjustable relative to the contact rod are provided in the respective casing part.

3 By this known arrangement, it is possible to carefully clean the lance head on its side facing the melt bath in the metallurgical vessel. In particular, it is feasible to keep clean sampling probe-bearing lances on their front ends such that the penetration of slag during the measuring procedure, at which the lance head is immersed at least into the slag layer covering the bath, between the measuring and/or sampling probe and the front end of the lance is prevented However, the arrangement according to AT-B 381 795 is relatively expensive and complex in terms of construction, in particular as regards the divided oscillating cleaning head.

The invention aims at avoiding these disadvantages and difficulties and has as its object to provide an arrangement of the initially defined kind, which is easy to produce at low costs and enables the perfect cleaning of the lance head at the largest operational safety possible. In particular, the milling head is to have a long service life.

In accordance with the invention, this object is achieved in that the arrangement comprises a central pipe arranged in alignment with the milling head and to whose upper end the milling head is rotatably fastened, that a centering means for the contact rod is provided on the central pipe near its upper end, that an end stop is provided at the lower end of the central pipe, which gets into contact with the contact rod, and that a drive motor is arranged at the central pipe for driving the milling head. Thereby, it is possible to allow the milling head to perform a rotational movement in one direction only, instead of the known oscillating movement, whereby its cutting teeth are moved in the cutting direction only and, thus, are spared. Hence follows a considerable increase in service life.

4 The central pipe enables the cleaning arrangement to positioned in a simple manner and the milling head to the lance axis are delimit the milling be b e precisely placed into the desired operation position by the centering means, in which position the milling head axis and in alignment. The end stop serves to stroke and the drive motor arranged on the central pipe ensures the operationally safe transmission of the driving forces.

In order to prevent rattling of the milling head during the milling procedure, the end stop is designed as a shock absorber, including a central piston resiliently mounted relative to the milling head.

Preferably, the end stop includes a conically shaped stop surf ace gett ing into contact with the contact rod, thus providing for improved centering of the contact rod during its advance.

According to a preferred embodiment, the centering means is formed by two rotationally journalled guiding rollers having their axes arranged horizontally and fixed relative to the central pipe, and by a third guiding roller, whose axis also is directed horizontally and is adjustable in the direction towards the axis of the central pipe.

Preferably, the two guiding rollers that are f ixable relative to the central pipe are precisely adjustable in their positions relative to the axis of the central pipe by an adjustment means, and, in particular, the adjustable guiding roller is adjustable in the direction towards the axis of the central pipe by a pressure-medium cylinder against the action of a spring means. In addition to providing for the optimumly centered position, the guiding rollers offer an excellent guidance of the central pipe on the contact rod.

According to a further preferred embodiment, the shock absorber comprises a hydraulic cylinder, in which the piston is slidably and tightly guided and whose cylindrical inner s p a c e, via a hydraulic conduit, communicates with the pressure medium cylinder displacing the adjustable guiding roller. Due to the advance movement of the piston, hydraulic oil is displaced from the cylinder interior and admitted to the pressure medium cylinder of the centering.means through the hydraulic conduit prior to starting the milling procedure. Thereby, the adjustable guiding roller is pressed at the contact rod, the contact rod, thus, automatically being centered into the position in alignment with the lance prior to starting the milling procedure.

In a particularly simple mode of construction, a cantilevering casing is provided on the central pipe near the milling head, to which casing a drive motor designed as a gear motor is fastened, which gear motor preferably is in connection with the milling head via a clutch and a gear arranged within the casing.

Suitably, the hydraulic conduit enters into the gear casing via a branch duct including an adjustable pressure relief valve. If the oil pressure adjusted is reached in the hydraulic conduit during the advance movement of the milling head, the pressure relief will be opened and hydraulic oil gets into the gear casing via the branch duct, where it serves to lubricate the gear parts and subsequently is recycled, via a return conduit, into an oil reservoir flowconnected with the hydraulic conduit.

According to a preferred embodiment, the central pipe has an external cross section approxima-tly corresponding to that 6 of.a measuring and/or sampling probe, which is detectable by means of a probe manipulator, wherein the arrangement for cleaning the lance head preferably is retained by a cleaner manipulator movable into the displacement path of the probe manipulator and out of the same. Thereby, it is possible to employ a probe manipulator as usually used to convey a probe from a magazine to a lance, for the manipulations of the cleaning arrangement necessary when cleaning the lance head. Suitably, the central pipe is equipped with a twist safety device in the contact regions getting into contact with the probe manipulator.

According to a further preferred embodiment, the cleaner manipulator includes a cleaner seat provided on a cantilevering arm, on which seat the arrangement for cleaning the lance head may be deposited and which is adjustable in height in the vertical direction. With this embodiment, the cleaning arrangement may be moved into a position in alignment with the lance also by the cleaner manipulator, the slipping of the cleaning arrangement on the contact rod and the milling advance of the cleaning arrangement being effected by an upward movement of the cleaner seat. With a preferred, particularly simple mode of construction, the cantilevering arm is made up of two parts, one part being adjustable in height relative to the other part along a vertical guide rail mounted on one part of the arm.

In order that the cleaning arrangement maintains as stable a position as possible during the manipulation procedures, a stirrup is connected with the central pipe, reaching with its stirrup legs as far as into a region located opposite the drive motor with respect to the axis of the central pipe and being provided with a counterweight in this region, thus ensuring the symmetry of the cleaning arrangement in terms 7 of weight. With a particularly space-saving and simple mode of construction, the counterweight preferably is designed as an energy storage, serving, in particular, to house accumulators.

The invention will now be explained by way of the embodiments illustrated in the drawing, wherein Fig. 1 is a partially sectioned side view of the cleaning arrangement in detail. Fig. 2 is a schematic top view onto an embodiment of the cleaning arrangement in various operation positions and Fig. 3 illustrates a side view in the direction of the arrow III of Fig. 2.

According to Fig. 1, a measuring lance 1, on its lance head 2, comprises a contact rod 4 extending in the direction of its axis 3 to receive a measuring probe and provided with a tapered projection 5 on its free end. During the measuring process, the lance 1, together with the measuring probe to be slipped on the contact rod 4, which is not illustrated in the figures, immerses, for instance, into the melt contained in a steelworks converter, i.e., through the slag floating on the melt, the lance head 2 frequently getting into contact with slag. The lance head 2, on its f ront end 6, has an annular recess 7, into which the upper end of the measuring probe may be inserted such that the penetration of slag or melt between the contact rod and the measuring probe, as a rule, will be prevented. This annular recess 7 and the region of the f ront end 6 of the lance head 2 immediately following thereupon must be kept free from slag and metal incrustations in order to be able to perf ectly receive a new measuring probe after having carried out a measurement, i.e., after having withdrawn a measuring probe from the contact rod, and to safeguard the contact between the contact sites 8 on the lower end of the contact rod and the corresponding contact sites of the measuring probe.

8 For this purpose, a cleaning arrangement 9 capable of being slipped on the contact rod 4 from below is laterally movable towards the lance 1 and back. This cleaning arrangement 9, in the slipped-on state, comprises a central pipe 10 coaxially surrounding the contact rod 4, i.e., arranged in alignment with the axis of the lance. On the upper end 101 of the central pipe 10 having a circularly ring-shaped cross section, a milling head 11 registering with the central pipe 10 is rotatable, yet immobilised in the vertical direction. The milling head 11 comprises a disc-shaped insert piece 13 abutting on the front end 12 of the central pipe 10 and rotatably inserted in an opening 14 of the upper part 15 of a gear casing 16 fastened to the central pipe 10. A f oot section 18 of the milling head 11 is inserted in a recess 17 provided on the upper side of the insert piece 13, by milling teeth 19 shaped in correspondence with the shape of the annular recess 7 of the lance head 2.

The milling head 11 is rigidly connected, e.g., by means of screws 22, with a spur wheel 21 arranged in alignment with the axis 20 of the central pipe 10 and flush-mounted at the insert piece 13. The spur wheel 21 is rotatably journalled on the external jacket 24 of the upper end 10' of the central pipe 10 by means of a bearing 23, abutting on the inner side 25 of a lower part 26 of the gear casing 16, thus being immovable in the axial direction. A pinion 27 arranged in a part of the gear casing 16 extending beyond the region of the spur wheel engages in the spur wheel 21. The axis of rotation 28 of the pinion 27 extends parallel to the axis 20 of the central pipe 10, the shaft 29 of the pinion being rotatably journalled in the gear casing 16 by means of bearings 30, 31. The shaft 29 of the pinion, with its lower end 32, reaches into a canti.levering casing part 33 extending parallel to the central pipe 10 and including a flange 34, to which a gear motor 35 is flanged.The pinion, 9 with its lower end 32, is connected with a driving shaf t 37 of the gear motor 35 via a clutch 36. In order to reach the weight symmetry of the cleaning arrangement 9, a stirrup 44 having two stirrup legs 45 is fastened to the central pipe 10 and to the gear casing 16, respectively, which extend as far as into a region disposed opposite the gear motor 35 with respect to the axis 20 of the central pipe 10 and are provided with a counterweight 46 in that region.

On the upper end 10' of the central pipe 10, a centering means 38 is provided. The centering means 38 comprises two guiding rollers 40 each arranged in a casing 39 that penetrates the jacket of the central pipe 10 and contacting the contact rod 4, their axes 41 each being directed horizontally and tangentially to the central pipe 10 and rotatably journalled in a retaining means 42, which is displaceable within the casing 39 horizontally to the axis 20. The retaining means 42 are each fixable in their positions relative to the central pipe 10 by means of an adjustment screw 43, the positions of the guiding rollers 40 being adjusted in accordance with the diameter of the contact rod 4 prior to slipping the cleaning arrangement 9 on the contact rod 4.

A third, adjustable guiding roller 47 of the centering means 38 also having a horizontally directed axis 48 is journalled at the level of the two fixable guiding rollers 40 on a retaining means forming a piston 49 of a pressure medium cylinder 50 penetrating the jacket of the central pipe 10. All the guiding rollers 40, 47 are arranged about the circumference of the central pipe 10 in a manner offset by an angle of about 1200. A screw 51 is screwed into the retaining means 49 of the adjustable guiding roller 47 by its shaft end and is guided in a plate 52 rigidly fastened within the pressure medium cylinder 50. The screw head is provided with a disc 51' sealingly guided along the cylindrical inner wall. Between the disc 511 and the plate 52, there are provided cup springs 53 pulling the retaining means 49 towards the plate 51', the adjustable guiding roller 47 thus being maintained at a distance from the contact rod 4 prior to starting the cleaning procedure. During the milling procedure, the adjustable guiding roller 47 is hydraulically pressed at the contact rod 4 by actuating the pressure medium cylinder 50, as will be explained in more detail below.

In the intermediate region 100 of the central pipe 10 located below the centering means 38, feather-key-like twist safety means 54 and a retention ring 55 are mounted. To the lower end 10"' of the central pipe 10 there is f langed a hydraulic cylinder 56 of a shock absorber 57 extending approximately over the region of the projection 5 of the contact rod 4. The cylinder head on the lower end of the hydraulic cylinder 56 is formed by a hat-shaped stop nut 58 fastened to the cylinder jacket and whose bottom 59 includes a centrical recess, forming a stop for an annular piston 60 guided within the hydraulic cylinder 56.

The annular piston 60 includes a passage bore 61 widened in its lower region 61', into which the proj ection 5 of the contact rod 4 reaches. The passage bore 61, on its upper end, is provided with a centering means 62 designed as a conical stop face for the contact rod 4, which has a counter stop face 63 in the transitional region to the projection, that corresponds to the stop face. To the bottom 59 of the stop nut 58, an external and an internal guiding sleeve 64, 65 for the annular piston 60 are fastened, arranged concentrically with the annular piston 60 and sealingly contacting its outer and inner circumferential surfaces, respectively. The annular piston 60 is supported on the 11 upper front end 67 of the internal guiding sleeve 64 by means of a pressure spring 66 provided in the widened lower region 611 of the passage bore 61, the conical stop face 62 of the annular piston 60, thus, being pressed at the counter stop f ace 6 3 of the contact rod 4. In th i s manner, t h e annular piston 60 is resiliently mounted relative to the milling head 11.

The cylindrical jacket of the hydraulic cylinder 56 comprises a vertical bore 67 extending parallel to the axis 20 of the central pipe 10 and, following thereupon, a horizontal bore 68 leading radially outwards, w h i c h constitute an oil channel. A hydraulic conduit. 71, which connects the annular inner space 70 of the hydraulic cylinder 56 with the inner space of the pressure medium cylinder 50 of the centering means 38 in a duct-like manner, follows upon the oil channel 69. In addition, the hydraulic conduit 71 runs into the interior of the gear casing 16 via a branch conduit 72, a pressure relief valve 74 to be adjusted by a pressure measuring device 73 being provided in the branch conduit 72. An oil supply duct 76 provided with a non-return valve 75, of an externally arranged oil reservoir 77, runs into the hydraulic conduit 71. The oil reservoir 77 is connected in a duct-like manner with the inner space of the gear casing 16 via a return conduit 78.

In the schematically illustrated embodiment according to Fig. 2, the cleaning arrangement 9 is retained by a cleaner manipulator 9 arranged on a platfo rm. The cleaner manipulator 79 comprises a sleeve 81 rotatable about a pivot axis 80, on which a radially cantilevering two-part arm 82 is arranged. The cantilever arm 82 is pivotable by means of an adjustment cylinder 83 hinged to a lever 84 rigidly fastened to the sleeve 81, the cleaning arrangement 9, thus, being movable along a circular path. of motion 85. The outer 12 part 86 carrying the cleaning arrangement 9 and constituting the free end of the cantilever arm 82 is liftable and lower a ble relative to the inner part 87 along a guide rail 89 rigidly fastened to a downwardly extending beam 88 of the inner part 87. The vertical displacement may be effected by means of a lifting cylinder 90 hinged to the vertical beam 88 on one end and to the outer part 86 of the arm 82 on the other end (cf. the cleaner manipulator illustrated in various positions in Fig. 3). The cleaning arrangement 9 is supported by a cleaner seat 91 on the outer part 86 of the cantilever arm 82 and can be lifted from the same.

On the platform, a probe manipulator 92 is arranged beside the cleaner manipulator 79. The probe manipulator 92 schematically illustrated in Fig. 2 is designed in a mann er similar to the arrangement for exchanging measuring or sampling probes known from EP-B 0 113 653. The probe manipulator 92 comprises a column 94 arranged on the platform and pivotable about an axis 93. A cantilevering console 95 is fastened to the column 94 so as to be displaceable in the vertical direction, a grab 96 being arranged on its free end.

The grab 96 usually serves to take a probe out of a magazine M indicated by dot-and-dash lines and to convey the probe to the lance 1 or to remove the probe f rom the lance 1, the probe being retained by pairs of tongs 97 of the grab 96.

As is apparent from Fig. 2, the grab 96 also is -movable on a circular path of motion 98, whose radius, however, is larger than the radius of the path of motion 85 of the cleaning arrangement 9. The two paths of motion 85 and 98 cross each other in a point of intersection 99.

The arrangement functions in the following manner:

1 13 The grab 96 of the probe manipulator 92 is pivoted into the path of motion 85 of the cleaner manipulator 79, into a reception position A illustrated by dot-and-dash lines, in which the axis 100 laid through the circular openings of the jaw pairs 97 lies in the point of intersection 99. Upon opening of the jaw pairs 97, the cleaning arrangement 9 is pivoted from the resting position B entered in full lines into the delivery position C illustrated in dot-and-dash lines, in which the axis 20 of the central pipe 10 is located in the point of intersection 99 of the paths of motion85 and 98, registering with the axis 100 laid through the circular openings of the jaw pairs 97. In this case, the height levels of the cleaning arrangement 9 and of the grab 96 are chosen such that the middle region 1C of the central pipe 10 is located at the level of the opened jaw pairs 97, the jaw pairs 97 each embracing the central pipe 10 at the level of the twist safety means 54 (cf. the tong jaws indicated by dot-and-das-h lines in Fig. 1).

The central pipe 10, whose external diameter 101, in the central region 1C1, corresponds to approximately the diameter of a probe, is clamped by the jaw pairs 97, which jaw pairs 97 do not embrace the central pipe 10 completely, but by leaving free a gap for the twist safety means 54 on each free end of the tong jaws. The retention ring 55 rests on the upper pair of tong jaws, thus preventing the central pipe 10 from sliding down. Subsequently, the cleaning arrangement 9 is lifted off the cleanier seat 91 of the cleaner manipulator 79 by lifting the console 95 of the probe manipulator 92 and lowering the cleaner seat 91, and the grab 96 is pivoted, together with the cleaning arrangement 9, into an operation position D below the lance head 2 illustrated in full lines, in which the axis 20 of the central pipe 10 registers with the axis 3 of the lance 1. (For reasons of clarity, only the probe manipulator 92, 14 without lance 1 and cleaning arrangement 9, is illustrated in Fig. 2 in the operation position D).

Subsequently, the console 95 of the probe manipulator 92 is moved upwardly and the central pipe 10 is slipped on the contact rod 4. As soon as the milling head 11 is in the appropriate position (approximately at 80 % of the entire stroke) below the lance head 2, the probe manipulator 92 switches to a milling advance at a lower advance speed after starting of the gear motor 35. The slag and metal incrustations adhering to the lance head 2 are carefully removed by the milling teeth.

During the milling procedure, the contact rod 4 pushes against the stop f ace 62 of the annular piston 60 of the hydraulic cylinder 56 by its counter stop face 63. Thereby, the annular piston 60 is shifted downwardly against the action of the compression spring 66 until the circularly ringshaped front end 103 of the piston contacts the bottom 59 of the stop nut 58. The advance of the milling head 11, thus, is limited by the distance 102 between the front face 103 of the piston and the bottom 59 of the stop nut 58.

On account of the annular piston 60 moving downwardly, the hydraulic oil is urged away from the annular inner space 70 of the hydraulic cylinder 56 and the pressure medium cylinder 50 of the centering means 38 is actuated via the hydraulic conduit 71, wherein the hydraulic oil is prevented from f lowing back into the oil reservoir 77 by means of the non-return valve 75. The adjustable guiding roller 47, thus, is pressed at the contact rod 4. Due to the annular inner space 70 of the hydraulic cylinder 56 getting smaller, the pressure of the hydraulic oil increases until the maximum pressure adjusted by means of the pressure measuring device 73 has been attained. Subsequently, the pressure relief valve 74 in the branch conduit 72 is opened and hydraulic oil gets into the interior of the gear casing 16.

As the piston front face 103 of the annular piston 60 of the hydraulic cylinder 56 gets into contact with the bottom 59 of the stop nut 58, the advance of the probe manipulator 92 and the gear motor 35 are stopped, which, preferably, is done automatically by means of an end switch. The probe manipulator 92 lowers the cleaning arrangement 9 as far as to below the contact rod 4 and is pivoted into the reception position A. Upon removal of the cleaning arrangement 9 by the cleaner manipulator 79, the latter is pivoted into the resting position B after the probe manipulator 92 has released the cleaning arrangement 9 by opening of the pairs of tong jaws 97.

According to a further embodiment, it is also possible to pivot the cleaning arrangement 9, by means of the cleaner manipulator 79, into a position in which the axis 3 of the lance 1 registers with the axis 20 of the central pipe 10 and to slip the cleaning arrangement 9 on the contact rod 4 by the aid of the cleaner manipulator 79. In this case, the stroke length of the lifting cylinder 90 must correspond to at least the length of the contact rod 4.

It is also possible to construct the cleaning arrangement in a manner that it is independent of any external energy supply. All the elements of the hydraulic system may be arranged on one frame together with the cleaning arrangement. The electric supply may be effected via accumulators or other energy storing means, which may then function as counterweights.

16

Claims (1)

1. Claims:

   An arrangement for cleaning a contact-rod (4)-bearing lance head (2) of a lance (1) to be introduced into a metallurgical vessel, in particular a lance (1) carrying a measuring and/or sampling probe, comprising a milling head (11) being in contact with the lance head (2) during the cleaning procedure, which milling head is capable of being placed into a position in alignment with the lance head (2) and lifted and lowered relative to the lance head (2) and the contact rod (4) receiving the measuring and/or sampling probe, characterised in that the arrangement comprises a central pipe (10) arranged in alignment with the milling head (11) and to whose upper end (10') the milling head (11) is rotatably fastened, that a centering means (38) for the contact rod (4) is provided on the central pipe (10) near its upper end (10'), that an end stop (57) is provided at the lower end (10"') of the central pipe, which gets into contact with the contact rod (4), and that a drive motor (35) is arranged at the central pipe (10) for driving the milling head (11).

   2. An arrangement according to claim 1, characterised in that the end stop is designed as a shock absorber (57), including a central piston (60) resiliently mounted relative to the milling head (11).

   3. An arrangement according to claim 1 or 2, characterised in that the end stop (57) includes a conically shaped stop surface (62) getting into contact with the contact rod (4).

   4. An arrangement according to one or several of claims 1 to 3, characterised in that the centering means (38) is formed by two rotationally journalled guiding rollers (40) having their axes (41) arranged horizontally and fixed 1 relative to the central pipe (10), and by a third guiding roller (47), whose axis (48) also is directed horizontally and is adjustable in the direction towards the axis (20) of the central pipe (10).

   5. An arrangement according to claim 4, characterised in that the two guiding rollers (40) that are fixable relative to the central pipe (10) are precisely adjustable in their positions relative to the axis (20) of the central pipe (10) by an adjustment means (43).

   6. An arrangement according to claim 4 or 5, characterised in that the adjustable guiding roller (47) is adjustable in the direction towards the axis (20) of the central pipe (10) by a pressure-medium cylinder (50) against the action of a spring means (53).

   7. An arrangement according to claim 6, characterised in that the shock absorber (57) comprises a hydraulic cylinder (56), in which the piston (60) is slidably and tightly guided and whose cylindrical inner space (70), via a hydraulic conduit (71), communicate.s with the pressure medium cylinder (50) displacing the adjustable guiding roller (47).

   8. An arrangement according to one or several of claims 1 to 7, characterised in that a cantilevering casing (16, 33) is provided on the central pipe (10) near the milling head (11), to which casing a drive motor (35) designed as a gear motor is fastened. - 9. An arrangement according to claim 8, characterised in that the gear motor (35) is in connection with the milling head (11) via a clutch (36) and a gear (21, 27) arranged within the casing (16).

   18 10. An arrangement according to one or several of claims 7 to 9, characterised in that the hydraulic conduit (71) enters the gear casing (16) via a branch duct (72) including an adjustable pressure relief valve (74).

   11. An arrangement according to one or several of claims 1 to 10, characterised in that the central pipe (10) has an external cross section approximately corresponding to that of a measuring and/or sampling probe and detectable by means of a probe manipulator (92).

   12. An arrangement according to claim 11, characterised in that the arrangement for cleaning the lance head (4) is retained by a cleaner manipulator (79) which is movable into the displacement path (98) of the probe manipulator (92) and out of the same.

   13. An arrangement according to claim 11 or 12, characterised in that the central pipe (10) is equipped with a t W i 5 t safety device ( 54) 1 n the contact r e 9 i o n s contacting the probe manipulator (92).

   14. An arrangement according to one or several of claims 1 to 13, characterised in that the cleaner manipulator (79) includes a cleaner seat (91) provided on a cantilevering arm (82), on which seat the arrangement for cleaning the lance head (4) may be deposited, and that the cleaner seat (91) is adjustable in height in the vertical direction.

   15. An arrangement according to claim 14, characterised in that the cantilevering arm (82) is made up of two parts, one part (86) being adjustable in height relative to the other part (87) along a vertical guide rail (89) mounted on one part (87) of the arm (82).

   1 1 19 16. An arrangement according to one or several of claims 1 to 15, characterised in that a stirrup (44) is connected with the central pipe (10), reaching with its stirrup legs (45) as far as into a region located opposite the drive motor (35) with respect to the axis (20) of the central pipe (10) and being provided with a counterweight (46) in this region.

   17. An arrangement according to claim 16, characterised in that the counterweight (46) is designed as an energy storage means, in particular, as an accumulator.

   18. An arrangement substantially as hereinbefore described with reference to the accompanying drawings.

   Published 1990 at The Patent Office, State House,66 71 11igh Holborn, London WCIR 4TP. Further copiesmaybe obtainedfrom The PatentOffice Sales Branch, St Ma-y Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltdi St Mary Cray. Kent. Con. 1187