43 815 K Tracto-Technik - Paul Schmidt Spezialmaschinen 5 ReiherstraBe 2, 57368 Lennestadt "Steerable underground rocket" 10 The invention relates to a method and an apparatus for boring in a specific direction using an underground rocket, in particular to a method for achieving and maintaining a specific nominal boring axis using the underground rocket, and to a steering element for 15 steering the underground rocket. Fundamentally, when boring underground, there is a need to guide the underground rocket to a specific destination, or to move it on a desired track. 20 Particularly when boring horizontally, the directional accuracy of the underground rocket, which in some cases is used in particular underground in densely built-up regions with a complex infrastructure, plays a major role. Firstly, the underground rocket must be able to 25 accurately reach a destination trench, which is frequently tightly constrained, in order to carry a pipe or a cable to a desired position, or in order to make it possible to emerge from the earth's surface at a specific point. Secondly, uncontrolled deviation of 30 the underground rocket from the nominal boring axis can lead to damage to underground pipelines or fittings. In the last 20 years, numerous underground rockets and methods for the operation of such appliances have 35 therefore been developed in the prior art, in order to steer an underground rocket as accurately as possible, or to move it in a straight line as reliably as possible.
- 2 The majority of the underground rockets which have been developed either operate on the principle that the rocket has a forward-drive head which can be moved from a central or symmetrical position to an asymmetric 5 position in order to initiate a turn for the underground rocket (Group I), or they have an asymmetric forward-drive head, with the forward-drive head or the underground rocket being rotated continuously when moving in a straight line, and with 10 the rotation being interrupted at a specific angular position in order to initiate a turn (Group II). A Group I appliance, that is to say an appliance with an adjustable forward-drive head, is described, for 15 example, in German Laid-Open Specification 37 35 018. Appliances such as these have a mechanism that is complex to a greater or lesser extent in order either to pivot a forward-drive head (which is symmetrical in the initial position) out of the symmetrical position 20 for example by means of an eccentric ring or in order to move an eccentrically mounted symmetrical forward drive head by rotation from the boring axis relative to the appliance. In all cases, the mechanism (which can be operated mechanically or hydraulically) leads to the 25 appliance being moved from a symmetrical "straight ahead" basic arrangement to an asymmetric "turning" arrangement. However, it is necessary to know the relative position of the forward-drive head with respect to the underground rocket in order to control 30 these appliances. This relative position can be transmitted by means of appropriate sensors to an operator, who can then use further measurement and display devices to determine the position of the underground rocket, and to change the movement 35 direction. In Group II steerable underground rockets, such as those described, for example, in US Patent Specification 4 907 658, a permanently asymmetric, for - 3 example inclined, forward-drive head leads to a continuous steering movement of the underground rocket when it is being driven forward. In order to move straight ahead, the underground rocket or the forward 5 drive head is caused to rotate, which leads to a tumbling boring movement of the appliance, running essentially straight ahead. In order to maintain the continuous rotation of the head or of the appliance, US Patent Specification 4 694 913 provides a mechanical 10 device which is arranged outside the borehole and uses a linkage to rotate the underground rocket. Although this apparatus and procedure allow the underground rocket to be controlled to a certain 15 extent, they involve considerable design and mechanical complexity since, in addition to the system for driving the underground rocket forward, a system must be provided for rotation, and a linkage must be provided for transmitting the rotation. The linkages are 20 relatively rigid, impede the steering process, and cannot be moved from the trench to the surface. In some appliances such as these, a constricted flexible linkage is used as the first linkage behind the underground rocket in order to allow the underground 25 rocket to carry out any steering movements whatsoever. Other underground rockets avoid this complexity for moving in a straight line by using their own systems for rotating the underground rocket or the forward 30 drive head, as is described, by way of example, in German Patent Specification 39 11 467. In all cases, the advantage of the steerability of an underground rocket leads to not inconsiderable use of 35 materials, costs and operating complexity. In addition to horizontal boring methods using underground rockets, boring methods and apparatuses are also known in which a linkage which is provided with a forward-drive head is introduced into the ground via a forward-drive unit which acts outside the borehole, as is described, by way of example, in German Utility Model Specification 92 07 047. In this method, the 5 linkage which is required for controlling or rotating the asymmetric forward-drive head is already provided for the forward drive and is used for rotation, so that the problem of rotation when moving underground rockets straight ahead does not arise. However, extensive 10 equipment must be provided for each borehole for this purpose and, in particular, must be transported (linkage, drive), thus increasing the amount of effort and the costs. 15 PCT Laid-Open Specification WO 94/05941 attempts to solve the problem of steering an underground rocket by means of a Group I appliance, in which the forward drive head can be moved from a symmetrical position (boring in a straight line) to an asymmetric 20 arrangement (turning) by rotation relative to the underground rocket. In this appliance, the forward drive head is in the form of a cone with stabilization elements, and has a longitudinal axis which is inclined to the longitudinal axis of the appliance. The forward 25 drive head has a rear contact surface, by means of which it makes contact with a front contact surface on the underground rocket, and on which the forward-drive head is rotated. The plane of these contact surfaces is inclined to the appliance longitudinal axis and to the 30 longitudinal axis of the forward-drive head. This makes it possible to rotate the appliance casing about its longitudinal axis, while the earth holds the forward drive head firmly. 35 Such casing rotation allows the forward-drive head to be moved to an eccentric position with respect to the appliance casing, in which position it will turn. The rotation angle - referred to as the difference angle in the following text - between the forward-drive head and - 5 the appliance casing or the two limit positions of the forward-drive head is governed by a driver pin, which is connected to the forward-drive head and engages in a circular slot in the appliance casing. When the pin is 5 located at one end of the appliance slot, then the forward-drive head is in its position for moving in a straight line (straight-ahead position), while, at the other end of the appliance slot, it is located in the position for turning (steering position). 10 In order to move the underground rocket from moving in a straight line onto a specific turning track, the appliance casing can be rotated by means of the compressed-air hose sufficiently for the appliance to 15 achieve the desired angular position (initial position) for the desired turning track. This rotational movement may be composed of two phases. In this case, the first phase is for only the appliance 20 casing to be rotated first of all, until the driver pin has moved through the entire difference angle from the straight-ahead position to the steering position. As soon as this has been done, the forward-drive head and the appliance casing are coupled to one another for the 25 rest of the rotational movement, that is to say the appliance casing and the forward-drive head rotate together until the initial position for turning is reached. In the process, considerable forces must be applied, since the forward-drive head has to move earth 30 by means of its stabilization elements during the rotation process. However, the stabilization elements are essential for operation of the described steering method. 35 If, in contrast, the driver pin is located in its steering position from the start, then joint rotation of the appliance casing and of the forward-drive head are at the same time linked to hose rotation. This situation occurs, for example, when the forward-drive - 6 head is accidentally moved to the steering position while boring in a straight line, so that a correction movement of the appliance casing is required, or when a direction correction is required while turning. 5 On the other hand, however, the forward-drive head can also accidentally be moved to the straight-ahead position while turning, so that it must be moved back again to the steering position by rotating the 10 appliance casing by means of the compressed-air hose. This can be done in one rotation direction by virtue of the rotation stop, and is thus highly complex. A further problem is that rotation of the forward-drive 15 head requires a considerable amount of force to be exerted, owing to the stabilization elements. In addition, it is also necessary to determine above the ground the angular position, with respect to the appliance longitudinal axis, in which the steering 20 position is located, that is to say that end of the casing slot which governs turning. If, for example, the steering position is in the 6 o'clock position when boring in a straight line and 25 it is intended to move the underground rocket from this position to a curved track running upward in a vertical plane, then the steering position must be changed to the 12 o'clock position. This is done by using the compressed-air hose to rotate the appliance casing. If 30 the forward-drive head or its driver pin is in the straight-ahead position, then the appliance casing is first of all rotated through the difference angle on its own until the driver pin is located at the other slot end in the steering position, and the casing is 35 then rotated, together with the forward-drive head which is now in the steering position, to the 12 o'clock position. Since the steering head position is unknown outside the - 7 borehole, it is also impossible to find out there what hose rotation is required - with or without overcoming the difference angle - to move the steering position to the correct initial position for turning. 5 Furthermore, difficulties occur when steering the underground rocket by means of the compressed-air hose. In the case of the described apparatus, the compressed air hose is rotated via a rotation apparatus which is 10 arranged outside the borehole. This rotation apparatus demands a special configuration of the hose, and is permanently attached to one hose section. A rotating ring is located between this hose section and the compressor, and allows the hose to rotate with respect 15 to the compressor. During operation, the rotation apparatus must either be moved forward continuously with the hose when the underground rocket is being driven forward, or must be arranged in the vicinity of the borehole such that the hose is not introduced 20 directly into the borehole, but via at least one loop. This makes it harder for the hose to rotate, and makes it impossible to use standard compressed-air hoses. Attempts have therefore been made to screw a clamping 25 ring consisting of two half shells to the compressed air hose, in order to exert a torque on the hose via steering rods which can be inserted into the clamping ring. Although an apparatus such as this avoids continuous movement of the rotation apparatus described 30 above, together with the hose, and avoids the problems of torque transmission with the loop arrangement which is required for the hose (see above), it has the disadvantage, however, that said clamping ring slides over the ground when the hose is being moved forward, 35 where it can become trapped and can impede the forward movement of the underground rocket, or can cause damage to the hose. A further problem is that the operator must first of all stop the underground rocket in order to exert the torque, and must insert the steering rods - 8 and then himself exert force on the hose, in the process rotating it. Furthermore, the half shells have to be continually unscrewed and moved through one hose section to the rear, in order to avoid being drawn into 5 the borehole. Since the hose section between the half shells and the borehole opening should be as short as possible, in order to prevent the hose from twisting outward during rotation, this requires the half shells to be continuously detached from and reattached to the 10 hose, and it is scarcely feasible to handle an appliance such as this during continuous operation. Manual steering apparatuses are known from the field of extrusion presses, which allow the boring rod to rotate 15 via a steering lever. However, these are arranged behind the forward-drive cylinder for the boring rods, so that the problem of changing the position as the forward driving process continues still exists in the same way, as does the problem of torque transmission 20 via a hose. Appliances such as these are thus not suitable for use on the hose of an underground rocket. Owing to the difficulties of determining the steering head position, the underground rocket which is known 25 from PCT Laid-Open Specification WO 94/05941 has been developed in accordance with German Laid-Open Specification 199 10 292 such that, when changing from movement in a straight line to turning, the forward drive head position at that time with respect to the 30 appliance casing and the position of the driver pin in the casing slot are determined first of all, and the appliance together with the forward-drive head is then set to the desired turning track, or is moved to the initial position for turning, by rotating the 35 compressed-air hose. However, the problem that it is impossible to avoid rotation of the forward-drive head for operation of the appliance still exists and, in practice, it has been found that the forward-drive head, in particular, is frequently virtually impossible - 9 to rotate in the highly compressed ground surrounding it, if it has stabilization elements. Furthermore, the stabilization elements on the forward-drive head result in uncontrolled deflection of the appliance in an 5 undesirable direction, which is generally offset through 900. Since, furthermore, this procedure means that the position of the appliance nose in space and the current 10 deviation of the appliance in the vertical and horizontal directions from the boring axis as well as the relative position of the forward-drive head and the appliance casing must be known, an appliance such as this can operate only with a double-roll sensor, or 15 some similar measurement device. In practice, the applicant is, however, not yet aware of any free-running underground rocket which is actually being sold and is used for more than just 20 experimental purposes. The invention is now based on the object of providing a method which allows an underground rocket to be steered and moved in a straight line easily. The invention is 25 furthermore based on the object of providing an underground rocket which is suitable for this method, and a suitable steering element for rotating the compressed-air hose. 30 In one solution according to the invention, although the underground rocket is not rotated automatically and continuously via the supply line, the underground rocket is rotated manually between two or more positions on a path section basis, that is to say 35 discontinuously via the supply line, with the geometric steering arrangement between the forward-drive head and the underground rocket not being changed during the boring process.
- 10 For turning, the underground rocket is driven forward without any change in its angular position over a path section of a desired length until it is aligned as desired. For moving in a straight line, the path 5 section-by-path section oscillating movement makes it possible to change between the 12 o'clock position and the 6 o'clock position in, for example, 1-meter boring steps. When moving in a straight line, this leads to a slight oscillating movement in the vertical axis. The 10 forward-drive head is then arranged symmetrically with respect to the horizontal plane, and this leads to there being no deviation from the straight-line nominal boring axis. 15 The invention thus allows an underground rocket to be steered easily, reduces the steering movement to a simple circular segment rotation in the desired direction without any additional compensation rotation of the forward-drive head, and at the same time avoids 20 the movement of compressed earth by stabilization elements, since the forward-drive head need not be rotated independently of the appliance. According to the invention, the process of rotating the underground rocket can additionally be made easier by mounting the 25 forward-drive head such that it can rotate. This should not be confused with a boring head which is mounted such that it can rotate symmetrically/asymmetrically, since the forward-drive head according to the invention keeps its asymmetric arrangement even while it is 30 rotating. The rotation capability, which is preferably achieved via a sleeve, is used to reduce the friction when carrying out steering movements. The use of a sleeve for reducing friction is not restricted to the forward-drive head. 35 An apparatus according to the invention for rotating the compressed-air hose, referred to as a hose steering device in the following text, allows the underground rocket to be steered easily, without impeding the - 11 forward drive of the underground rocket. The hose steering device furthermore allows steering on a hose section immediately before the hose enters the ground, without any need for a hose loop. 5 The hose steering device preferably acts via steering jaws (which are operated by a pressure medium) on the hose, and can be released, moved and clamped in place again with a small number of actions. The pressure 10 medium unit may in this case be manually operated and may have a pressure-medium tank, which forms a unit together with the hose steering device. The hose steering device according to the invention is 15 preferably guided via a guide frame, which moves the steering section of the hose to a level allowing it to be operated ergonomically, and prevents the hose from twisting outward when the torque is exerted. The guide frame allows the hose steering device to be rotated 20 together with the hose in a simple manner, in any desired directions, and even back on itself. It is self-evident that the expression guide frame is not restricted to frame structures but also covers any 25 other types of "stand" with the same function. A method according to the invention for moving the underground rocket in a straight line and for turning it allows the use of simple, free-running underground 30 rockets, which can be transported in any motor vehicle, thus avoiding the normal transportation effort and costs. The use of known measurement systems to measure the 35 inclination of the underground rocket makes it possible to compensate for any undesirable deviation from the nominal boring axis by lengthening a path section of an oscillating deflection toward the nominal boring axis, and thus by making the oscillation axis coincide with - 12 the nominal boring axis, once again. There is no need for complex measurement systems for determining the roll position of the casing relative to the deflection. This allows low-cost, commercially available probes, 5 receivers and display units to be used, such as those which can otherwise be used only in conjunction with a continuously rotating, asymmetric underground rocket of the type described initially (Group I) . The probe may have measurement devices for the inclination, roll, 10 temperature and battery charge level, and is then connected in a rotationally fixed manner to the forward-drive head, to the forward-drive head holder or to the casing of the underground rocket, for example in the way described in German Patent Specification 15 195 34 806, to the forward-drive head or to the underground rocket. Furthermore, the probe also allows the depth and azimuth direction of the underground rocket to be determined. 20 It is particularly advantageous to operate the underground rocket in the reverse direction before or during the rotational movement, in order to make the rotational movement of the underground rocket easier, as can be done, by way of example, by means of the 25 automatic compressed-air reversing control described in German Patent Application 198 58 519.5. Alternatively the underground rocket can be operated with no-load movements in the forward and reverse directions during rotation, so that it moves backward and forward in the 30 borehole during rotation, thus avoiding the forward drive friction on the forward-drive head while boring, so that there is no need to overcome this friction during manual rotation of the underground rocket. 35 In one preferred embodiment, the compressed-air reversing control is controlled by an electrical remote control. The reversing control can also be designed such that the underground rocket automatically carries out a number of rearward movements for as long as it is - 13 rotating. If the underground rocket is operated in one and the same angular position over a lengthy path section, it 5 follows a curved track which is governed by the asymmetry of the forward-drive head. For example, when an underground rocket is crossing underneath a road, it can be moved to the desired depth by boring in the 6 o'clock position, can be passed under the road moving 10 in a straight line by oscillating between the 12 o'clock position and the 6 o'clock position on 1-meter long sections, and can be steered back to the surface of the ground on the other side of the road by operating it in the 12 o'clock position. 15 The invention allows the use of an underground rocket whose design is extremely simple, using a procedure which is particularly simple to learn and easy to carry out, without any significant outlay for additional 20 devices and without dispensing with the capability to steer the underground rocket accurately to a destination. Since the operator can steer the underground rocket in the desired direction using the "steering wheel/steering column" principle that is 25 known from motor vehicles, and just has to "follow" a slightly meandering line in order to move in a straight line, although this is compensated for by the relatively long machine casing of the underground rocket, this underground rocket is considerably easier 30 to operate than conventional steerable underground rockets with complicated display apparatuses and operating instructions. The invention will be explained in more detail in the 35 following text with reference to exemplary embodiments which are illustrated in the drawing, in which: Figure 1 shows a steerable underground rocket in operation according to the invention; - 14 Figure 2 to Figure 5 show various embodiments of ram heads according to the invention; 5 Figure 6 shows an underground rocket according to the invention, with a position transmitter, damping system and appliance casings; 10 Figure 7 shows a torquer; Figure 8 shows an illustration of boring in a straight line; 15 Figure 9 shows an illustration of steering using a torquer; Figure 10 shows an illustration of the hose/appliance coupling according to the invention. 20 Figure 11 shows a detailed view of the hose steering device according to the invention; Figure 12 shows an illustration of the hose steering 25 device from Figure 11 in a guide frame. An underground rocket 1 with a forward-drive head 2 is connected via a supply line 3 to a hydraulic or pneumatic drive unit (not shown) and is driven forward, 30 starting from a starting trench 4, via a nominal boring line 5, into a destination trench 6. A torquer 8 with a steering handle 9 is arranged on the supply line 3 in the region of the starting trench 4. 35 Figure 1 shows the underground rocket 1 with the forward-drive head 2 in the 12 o'clock position (in the upward direction), with the asymmetric forward-drive head 2 predetermining the profile of the borehole when the underground rocket is not being rotated. In order - 15 to achieve the boring profile illustrated as a dashed line representing the nominal boring line 5, the torquer 8, 9 is just held in the position illustrated in Figure 1, unless any deflection is required in order 5 to correct for deviations from the desired boring line. The forward-drive head 2 has an asymmetric arrangement (Figures 2 to 4) or an eccentric forward-drive application of force (Figure 5) throughout the entire 10 boring process. The forward-drive head illustrated in Figures 2 and 3 is physically located in an arrangement in which the axis 22 of the forward-drive head 2 differs from the axis 11 of the underground rocket. When the underground rocket 1 is not being rotated, 15 such a forward-drive head configuration leads, during boring, to the underground rocket 1 deviating in the direction of the forward-drive head axis 22. When the underground rocket is rotated by means of the torquer 8, 9 via the supply line 3, the angle a is maintained 20 between the underground rocket axis 11 and the forward drive head axis 22. Only the direction of the axis 22 changes and, depending on the characteristics of the earth, also the direction of the axis 11 with respect to the boring line. 25 In order to maintain the angular position of the forward-drive head 2, the underground rocket 1 has an angled head adapter 12 with a mounting bolt 13, onto which the forward-drive head 2 is placed. The head 30 adapter 12 is connected to the underground rocket 1 via a bayonet connection 91 by means of a locking bolt 92 (Figure 6a), or directly by means of a locking bolt 93 (Figure 6b), allowing the forward-drive head to be fitted and removed easily, and thus also making it 35 easier to replace and insert the transmitter batteries. The head adapter 12 has a circumferential groove 14, on which the forward-drive head 2 is secured by means of locking pins 15, 16. This arrangement allows the forward-drive head 2 to rotate freely on the head - 16 adapter 12, but without any change to the angle a. This configuration leads to a considerable reduction in the static friction when the underground rocket 1 is rotated in order to carry out a steering movement. In 5 practice, it has been found that the greatest friction forces act in the region of the forward-drive head 2, in which the earth is compressed to the greatest extent, during rotation. The forward-drive head 2, which can rotate according to the invention, largely 10 avoids the static friction and sliding friction between the outer surface 24 of the forward-drive head 2 and the surrounding earth. Alternatively, the connection between the forward-drive 15 head and the head adapter may also be rigid, as is shown in Figure 6b. In this case, the forward-drive head can be connected to the head adapter via a pair of clamping sleeves 94. 20 Thus, in order to change the steering direction with an angled forward-drive head, deflection work need be carried out only in the region of the forward-drive head 2 when the underground rocket is rotated. Any desired rotation direction may be used in this case. 25 The shortest route is preferably chosen to reach the chosen roll position. In order to further reduce the static and sliding friction while steering, the underground rocket 1 has a 30 casing sleeve 17 which is connected to the underground rocket casing such that it can rotate. The forward drive head 2 as illustrated in Figure 5 allows the steering movement to be carried out particularly easily, since the forward-drive head 2, which is 35 located in the compressed tip of the borehole does not change its position when the underground rocket is rotated. Furthermore, sufficient space is available for the underground rocket 1 to rotate, since the forward drive head 2, as shown in Figure 5, has a larger - 17 diameter than the underground rocket. The friction to be overcome during rotation is essentially reduced, when using a forward-drive head 2 as shown in Figure 5, to the friction resulting from the weight of the supply 5 hose 3 lying in the borehole. Independently of this, the resistance to be overcome during rotation, in particular when using ram heads as shown in Figures 2 and 3, can be reduced by 10 interrupting the forward drive of the underground rocket 1 and/or by moving the underground rocket backward by reversing it out of the tip of the borehole, and/or by moving it backward and forward. This may be advantageous in particular when the earth 15 in the region of the forward-drive head 2 is highly compressed, when the ground would result in excessive resistance to the walking movement that takes place during rotation. 20 The underground rocket 1 has a compact position-finding system with shock absorption 18, which transmits the normal information, such as the position, depth inclination and roll position of the underground rocket 1, to a display apparatus (not shown) in the area where 25 the operator is located. The use of a compact position finding system 18 is particularly advantageous and is made possible, in particular, by avoiding a double-roll sensor. A sensor such as this is normally used for determining the relative position of the forward-drive 30 head and the underground rocket, although this is not necessary when using the arrangement of the forward drive head 2 which is (geometrically) static according to the invention 35 The hose steering device 8 comprises a holding grip 9, clamping jaws 81, 82 and a hydraulic hand pump 83 for applying pressure to the clamping jaws. A pressure medium tank 86 is arranged in the region of the hydraulic hand pump 83. The clamping jaws have rubber - 18 dampers 84, 85, which engage around the supply hose 3 when the hydraulic hand pump 83 is operated, ensuring that the hose steering device is seated firmly on the supply hose 3. The holding or steering grip 9 allows a 5 rotational movement to be transmitted to the supply hose 3 from the hose steering device (Figure 9) . This leads to rotation of the underground rocket and, in the embodiment illustrated in Figure 3, to the positions of the forward-drive head 2 as shown in Figure 8. 10 The supply hose 3 is routed via a guide frame 70 outside the ground. The guide frame has two guide elements 72, 74 spaced apart from one another. The guide elements preferably have one or more rollers 15 which are mounted such that they can rotate, in order to minimize the friction on the hose. The supply hose 3 is introduced into the guide frame 70 via the input guide element 72, and emerges from the guide frame 70 via the output guide element 74. The hose steering 20 device 8 is arranged in the hose section located between the guide elements 72, 74, with the guide frame 70 being at a level which allows ergonomic operation of the hose steering device 8. The distance between the guide elements 72, 74 is chosen such that the hose 25 steering device can be operated without any problems in the hose section defined in this way. This makes it simple to rotate the hose, even through 1800 or more, in any desired rotation direction. 30 For relatively long forward-drive sections, the operator can now release the hose steering device, so that it hangs freely on the supply hose 3 during forward drive on the guide frame 70. The hose steering device may, however, also still remain clamped to the 35 hose, provided that the relevant section has not yet reached the guide element 74. The supply hose 3 is coupled to the underground rocket 1 in a rotationally fixed manner. Figure 10 shows one - 19 embodiment of such a coupling. In addition to a rotation protection device 32, 33, which engages in the form of a shoulder in grooves on the reversing cone 35, the embodiment illustrated in Figure 10 has a securing 5 device against axial shear forces in the form of clamping sleeves 36, 37 which, when the machine is moving forward, ensure that the controller - by virtue of the weight of the hose - is not drawn out of the machine.