DE8801328U1 - Device for covering an elongated object such as a bridge cable - Google Patents

Description

Klaus Teeoh,

Hamburg &rgr; 12726/88

D/fi

Description

The invention relates to a device for covering an elongated object such as a bridge suspension cable with a sheath tube made of weldable material, in particular stainless steel.

The corrosion protection of the supporting cables of suspension bridges with anti-corrosive coating has proven to be inadequate. Permanent protection is promised by a corrosion-resistant coating, especially made of stainless steel, in conjunction with a filling of a suitable gaseous or liquid protective medium (oil, nitrogen, noble gas), which excludes the entry of corrosive substances, especially oxygen. The coating is a subsequent measure on the fully installed and loaded cable. This is generally not possible by winding and welding a sheet metal strip in a helical manner, because it requires large and flexible devices that cannot be arranged on the freely spanned cable and for which there is insufficient space when several cables are arranged in groups. The welding in the longitudinal direction of one or more cables laid in the longitudinal direction of the cable is also a problem.

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Longer lengths of sheet metal strips that are bent around the circumference of the rope are hardly realistic, because bringing the sheet metal strips to the rope and bending them places high demands on accuracy that can hardly be met in the free rope area, and requires a considerable distance that is not available under the confined space conditions of a group arrangement of ropes.

The invention is therefore based on the object of creating a device which allows the sheathing of an elongated object even under difficult conditions.

The invention is based on the idea of gradually producing the cladding tube at the end or at another easily accessible location of the elongated object and, as production progresses, advancing it into the area of the elongated object that is less easily accessible. The invention is also based on the idea of starting from pipe shell pieces of limited length for the production of the cladding tube, which can be prefabricated with high precision and can be attached to the elongated object at the production location without the need for an extensive bending section.

According to the invention, the implementation of these ideas is made possible by a device which comprises a guide frame which can be fixed in a centered manner to the elongated object and which has a movement guide for a welding device arranged parallel and concentrically in a rotational manner to the elongated support , a centering device for several pipe shell pieces which complement one another over the circumference to form a pipe piece, and a feed clamp which is connected to the guide frame via a feed drive and which can be detachably connected to the elongated object or the casing pipe.

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In general, the guide frame is permanently fixed in a centered position on the elongated workpiece during a long working period and is used to produce the casing pipe by inserting the pipe shell pieces, which are delimited by two parallel shell lines and two circumferential lines and are preferably half-shell pieces, and welding them together and to the previously produced pipe piece using the welding device which can be moved in the longitudinal and circumferential directions. After each new pipe piece has been completed and connected to the previously formed casing pipe, the feed clamp is moved close to the

Guide frame connected to the cladding tube and the entire cladding tube is pushed forward with the last pipe section formed. The welding area of the device is thus freed up for the formation of a new pipe section. The elongated object is gradually pulled over the cladding tube in this way.

In this way, extremely long sheathing tubes can be produced relatively easily, even for elongated objects which are partially inaccessible or difficult to access. This eliminates the difficulties which, when produced in the open rope area, could easily lead to disruptions, welding errors, insufficient control, dangerous and time-consuming accessibility for the operating personnel and similar disadvantages. The feed force can be applied mainly by pulling on the free end of the sheathing tube, so that the entire feed force does not ^have to be introduced via the feed clamp. However, the feed clamp, in conjunction with the feed drive, ensures the accuracy of the feed path, which is an advantage for consistently high-quality welding operations.

It is advisable to provide welding devices within the guide frame at the points intended for the welds between the pipe shell pieces, which cover the surface of the elongated object and protect it from the effects of welding. They can be attached directly to the elongated object or held by the guide frame.

According to a special feature, protective gas guides are provided, which can be formed by these welding protection devices, so that the welding can be under protective gas not only from the outside welding device, but also from the inside of the cladding tube. The protective gas guides are expediently formed by elongated recesses along the course of the weld seams, which are surrounded by side strips that prevent or inhibit the flow of the forming gas.

According to a special feature of the invention, these side strips are designed as centering counter bearings, which interact on the inside of the cladding tube with the centering elements acting on it from the outside and thus contribute to an exact positioning of the pipe shell pieces and the edges to be welded together and absorb the centering tension. The precise positioning of the sheets that is possible as a result contributes to a high quality of the weld seams, to the automation of the welding process and to the usability of thin sheets.

Centering of the pipe shell pieces is particularly desirable for the longitudinal seams, because the risk of failure due to the heat during the welding process is greater than for the undercut seams. In many cases, it is therefore sufficient to use

Hold-down devices should be provided near the welding device, which are pressed against the workpieces and their centering counter bearings in the form of clamping shoes, skids or pressure rollers and can be moved with the welding device. For the positioning of the pipe shell pieces, one or more centering clamping devices can also be provided, which are formed by forming shoes^* that complement each other essentially to the full extent and can be clamped centripetally against the pipe shell pieces.

The welding process can be preceded by a tacking process to ensure that the workpieces are secured in the correct welding position before the main welding process introduces significant amounts of heat and the risk of distortion. However, in many cases tacking can be omitted due to the good centering and tensioning of the workpieces.

For the movement of the welding device, a motor drive is expediently provided in both the rotational and longitudinal directions, which enables automatic operation, possibly with computer support. According to a further feature of the invention, the rotational drive can be set to a partial rotation corresponding to the peripheral part of the pipe shell pieces, i.e. to 180° if the pipe shell pieces are designed as half shells. This feature makes it possible to use the pipe shell pieces forming the cladding pipe with a mutual longitudinal offset. This is not only expedient in terms of strength considerations, but also contributes to manufacturing accuracy. If pipe shell pieces that are not offset from one another create seams that run all the way around the ends of the pipe pieces formed from them, there is a risk that, if there are slight inaccuracies in the length of the individual pieces at the peripheral seams, the welding process will be interrupted.

the distances between the edges to be welded together are too large.

In general, the guide frame, the welding carriage and the feed clamp cannot be placed on the elongated object from the free end. They are therefore expediently designed to be divisible so that they can be mounted on it from the side.

In some cases it is possible to connect the guide frame to the elongated object only on the side facing away from the sheathing tube being formed and to center it relative to it. However, particularly if the guide frame is very long, it will often be desirable to support it at the end facing the sheathing tube. This support can usually be found outside the elongated object, for example via support legs resting on the bridge. If instead support is only possible relative to the sheathing tube, it may be useful to provide an abutment for a centering clamp of the guide frame within the sheathing tube.

In order to center the sheath tube and reduce friction, sliding spacers can be provided on the elongated object, primarily outside the sheathing device, for example Teflon-coated rings or spring tongues protruding obliquely from the elongated object in the longitudinal direction and held on clamping rings. Low friction can be achieved by coating with a polyfluorocarbon.

The invention is explained in more detail below with reference to the drawing, which illustrates an advantageous embodiment. Therein t show

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Fig. 1 is a side view of the device, Fig. 2 to 6 Sectional views in directions of Arrows I to VI, Fig. 7 is a sectional view in enlarged

Scale of the shielding gas guide rails.

The guide frame is formed by the end plates 1, 2 and four angle profiles 3 connecting them at the corners. A clamping head 4 is arranged on the end plate 2, which consists of two clamping shoes 5, which are held on the end plate 2 by means of slotted hole guides 6 and can be moved towards and away from each other by means of piston-cylinder devices 7. They enclose a clamping opening 8, the size of which is dimensioned according to that of the sheathing pipe 9 to be formed around the supporting cable 10 of a suspension bridge. When the clamping shoes 5 are moved together hydraulically or pneumatically, the pipe 9 is firmly clamped by them. When they are moved apart, the pipe 9 can be moved in the clamping opening 8.

Guide rollers 16 are provided on the inside of the front plate 2 for mutual guidance of the guide frame and the pipe.

In the longitudinal corners of the guide frame are the cylinders 11 of piston-cylinder devices, which essentially run along the entire length of this frame, the piston rods 12 of which protrude from the front plate 2 and, in alignment with the guide frame, carry the pre-thrust clamp 1?, which consists of a

Plate 14 and a clamping head IS, which is designed in the same way as the clamping head 4. On the side facing away from the clamping head 15, the plate 14 carries guide rollers 17, which interact with the surface of the pipe 9 and support the feed clamp on the pipe.

The piston-cylinder devices with the clamping head 4 and the feed clamp 13 form a feed device through which

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this can be pushed forward. In general, the device is arranged stationary and the pipe 9 is pushed step by step over the rope 10. However, the reverse movement arrangement is not excluded, in which the pipe 9 remains stationary and the device at the end of the gradually lengthening pipe is pushed forward relative to the rope. The feed takes place in such a way that when the clamping head 15 is tensioned and the clamping head 4 is open, the push rods 12 are extended and then the clamping head 4 is tensioned and the clamping head 15 is opened when the push rods 12 are retracted again.

The front plate 1 of the guide frame contains an opening 20, the size of which is just large enough to accommodate the rope 10, so that the guide frame is centered at this end relative to the rope 10. If desired, the opening 20 can be made so small (if necessary using spacers) that the front plate 1, which is split and pulled together with bolts 21, and thus the entire device, sits firmly axially on the rope 10. Just like the front plate 1, the selenium plate 2 and the pre-closing plate 13 are split so that they can be mounted on the rope 10.

The other end of the device is centered on the pipe 9 by the clamping head 4, which in many cases is sufficient regardless of the axial position of the pipe in relation to the cable 10. However, the pipe 9 can also be centered in relation to the cable by means of the spacers 22 shown in Fig. 3 without giving any details, which can be imagined as being held on the cable 10 (for example with a clamp). These can have some play in relation to the inner circumference of the pipe 3 and can optionally be coated to facilitate sliding (for example with PTFE) in order to facilitate the advance of the pipe. Appropriate sliding spacers 22 can be provided over the entire advance path of the pipe, i.e. generally over the entire length of the cable 10, at certain intervals of, for example, 0.5 to 2 meters.

Inside the front plate 1, in its lower half, there is a receiving recess 23 for receiving the left end of a pipe half-shell 24 in the drawing in a position sufficiently centered to the rope. It is equipped with two hold-downs 25 that act on the upper edges of the inserted pipe half-shell 24 in order to position it in the correct position in the receiving recess 23.

The other end of the pipe half-shell is positioned by means of the welding carriage's devices, which will be explained later.

The upper pipe half-shell 26 is placed with its longitudinal edges on the lower pipe half-shell 24 and positioned in this position at its left end by clamps 27. Appropriate positioning means can also be provided at the right end, for example in the form of a clamp 28 placed from above, which can be removed if necessary as soon as the right end of the pipe half-shells is fixed by welding.

In the angle profiles 3 of the guide part, the welding carriage 30 can be moved in longitudinal direction, the guide rollers 31 of which interact with opposite edges of the angle profiles 3. The guide rollers 31 are arranged on the front plates 32, 33 of the welding carriage, which are rigidly connected to one another by rods 34. A drive arm 35 is provided on the front plate 32, which carries a motor 36 with a drive roller 37, which engages in a rack 3t arranged on the guide frame in order to move the welding carriage in the longitudinal direction. The arm 35 can be folded in such a way that the rack engagement can be released at will if the welding carriage is to be moved quickly.

Inside the welding carriage, guide rollers 39 are arranged on the front plate 32, which center the pipe being formed relative to the welding carriage. Outside the welding carriage, to the left of the front plate 32 in the drawing, guide rollers 40 are provided, which also serve to center the pipe parts, in particular the newly inserted pipe half-shells 24, 26 that are not yet connected to the pipe, and to ensure the correct mutual position of the edges forming the weld seams. Instead of all guide rollers, suitable sliding shoes can of course also be used.

The right front plate 33 of the welding carriage 30 carries a slewing ring 44 concentrically to the other parts of the welding carriage; this is guided, for example, by guide rollers 45 in an annular groove 46 of the front plate 33 and has a motor drive (not shown). The slewing ring 44 carries two welding devices 47 of a known type, such as those used, for example, to carry out the TIG process. It comprises a support arm 48 which is mounted on the holder 49 around a tangential axis and is spring-loaded to

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which is sucked towards the expanded pipe - for example, it is located on a slide 50 resting on the surface of the pipe, whereby its height relative to the slide SO can be adjusted by means of a rotary knob Sl. At its end it carries the welding head 52. Preferably, it can also be moved on the holder 49 in the direction of the tangential axis, i.e. in the circumferential direction of the pipe.

If nominal pipe half-shells are used, two welding devices are provided diametrically opposite each other on the welding carriage. In the circumferential direction, their position relative to the weld seam is adjusted by rotating the slewing ring. This requires that the offset of both seams takes place in the same circumferential direction of rotation. Other offset errors, which are caused, for example, by insufficient centering of the pipe in relation to the welding carriage, can be corrected by the aforementioned adjustment of the ', welding device in the direction of the tangential axis on the bracket 49.

Just like the guide frame and the feed clamp, the parts of the welding carriage 30 that enclose the rope are split so that they can be mounted on the rope from the side.
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In the drawing, to the left of the welding device 52, a centering or holding-down roller 55 is provided on the front plate 32 of the welding carriage, which presses with its thickened edges on each of the two edges to be connected. Two independent rollers of this type could also be provided. This is to ensure that the longitudinal welding edges are correctly positioned regardless of any thermal distortion. Since such a holding-down roller 55 is also provided on the second, diametrically offset welding device and the holding-down forces of these two

Rollers compensate for each other, it is not necessary in many cases to provide an abutment directly below the held-down edges (i.e. between the pipe halves to be welded and the rope surface). However, this can be useful for correct positioning even under difficult welding conditions and can also be easily provided, namely in conjunction with a shielding gas guide device, which is desirable anyway. According to Fig. 7, this consists of a shielding gas guide bar 60 located under each weld seam, which §

a recess 62, enclosed by two edge strips 61, forms below the weld seam 63. The two strips 60, which are provided diametrically opposite one another, are mounted on the cable 10 by means of a clamp band 63, with a spacer 64 being enclosed in the end of the clamp, which is arranged at the top of the cable in order to contribute to the weight absorption and guidance of the pipe on the cable 10. The shielding gas guide strips 60 extend over the entire length within which welding takes place on the cable and at the same time form a protection for the cable surface against possibly undesirable effects of the welding process. The edge \

strips 61 form abutments for the hold-down rollers 55. *

Corresponding strips can also be provided below the circumferential weld seams if this appears desirable for the supply of protective gas, for the protection of the rope or as a hold-down abutment. The latter is less important for circumferential weld seams because they are less prone to distortion than the longitudinal seams.

The device is used in the following way. After the stirring frame 1/ 2, 3 on the rope or centrically

sum rope is fixed to external structural parts, the welding carriage 30 is moved to the position shown in Fig. 1

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A pipe half-shell 24 is placed in the receiving trough 23 and on the guide rollers 40 and positioned using the latches 25. A second pipe half-shell 26 is placed on the pipe half-shell 24 with a longitudinal offset of a few centimeters and positioned using the clamp 27, suitable guide rollers (not shown) of the welding carriage 30 and/or the clamp 28. The welding carriage 30 is brought with the welding device 52 over the right end of the longitudinal seam 58 and this is either tacked or, if sufficiently supported, completely welded. The first pipe section thus formed is pushed by hand into the area of the feed clamp 13 and pushed forward with its help so gently that the rear, left peripheral edges are approximately in position 59. Two further pipe half shells 24, 26 are then inserted and pushed onto the rear peripheral edges 59 of the previously formed pipe section. The welding process then begins with the longitudinal seam area 57 and at least at the beginning of the longitudinal seam 58. The peripheral seams 59 are only welded after this. If desired, this sequence can also be modified. The longitudinal offset of the pipe half shells prevents four weld seams from meeting at one point and makes the length tolerances of the pipe half shells independent. After the longitudinal seam 58 and the peripheral seams 59 are closed, the pipe section thus formed is pushed forward using the feed clamp 13 and the process begins again. Suitable control devices (not shown) are provided for largely automatic operation.

It is not necessary that the sheathing device is absolutely firmly connected to the rope in the longitudinal direction. More important is the longitudinal connection of the device to the rear end of the pipe for the purpose of precise positioning of the pipe half-shells to be welded to it. Likewise, less

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on an exact centering of the device to the rope rather than to the pipe being constructed. Whether the desired position of the device to the pipe or the rope is ensured by fastening it to the rope or by fastening it to external structural parts (e.g. bridge body) is of secondary importance for the invention.

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Claims (12)

1. Device for covering an elongated object such as a bridge support cable with a sheathing tube made of weldable material, in particular stainless steel, characterized in that it comprises a guide frame (1, 2, 3) which can be fixed in a centered manner to the elongated object (10) and has a movement guide (3, 44) arranged parallel and concentrically in rotation to the elongated object (10) for a welding device (47), a centering device (23, 16/ 39, 40, 55) for several pipe shell pieces (24, 26) which complement one another over the circumference to form a pipe (9), and a feed drive (11, 12) connected to the guide frame (1, 2, 3) and connected to the elongated object (10) or the sheath tube (9) releasably connectable feed clamp. 2. Device according to claim 1, characterized in that the guide frame has guide rails (3) arranged parallel to the elongated object and a welding carriage (30) guided thereon with at least one welding device (47) arranged on the rotary guide (44). 3. Device according to claims 1 or 2, characterized in that welding protection devices (60) are provided within the guide frame (1, 2, 3) on the elongated object (10) at the locations intended for weld seams (58) between the pipe shell pieces (24, 26). 4. Device according to one of claims 1 to 3, characterized in that protective gas guides (60) are provided with a recess (62) enclosed by side strips (61) and following the weld seam path. 5. Device according to claim 3 or 4, characterized in that the welding protection devices (60) or the side strips (61) of the protective gas guides (60) are designed as counter bearings for a centering clamping device and/or for hold-down devices (55). 6. Device according to one of claims 1 to 5, characterized in that a motor drive is provided for the movement of the welding device (47) along the guides (3, 44). 7. Device according to claim 6, characterized in that the drive for the rotary movement can be divided into a half-revolution. 8. Device according to one of claims 1 to 7, characterized in that the welding carriage (30)/the guide frame (1, 2, 3) and/or the feed clamp (13) are divisible for the purpose of lateral mounting on the elongated object (10). 9. Device according to one of claims 1 to 8, characterized in that the centering device comprises mold shoes (5) which complement one another essentially to the full extent and can be clamped centripetally against the pipe shell. 10. Device according to one of claims 1 to 9, characterized in that the centering device and/or a hold-down device is formed by skids, rollers (55) or the like on the welding carriage. 11. Device according to one of claims 1 to 10, characterized in that sliding spacers (22) for receiving the sheath tube are provided on the elongated object (10). 12. Device according to one of claims 1 to 11, characterized in that the pipe shell pieces (24, 26) forming the cladding pipe (9) are arranged offset from one another in the longitudinal direction.