EP0385561A1 - Device for cleaning the surface of a hot upturned end of a tube - Google Patents

Abstract

The invention relates to a device for cleaning the surface of a hot-upset end of a tube by means of a blasting nozzle and a supply line, connected to the blasting head, for a gaseous carrier medium and blasting material. With the blasting lance, the blasting head (5) forms a compact unit and the blasting nozzle (7, 7') is arranged at an angle to the insertion end of the tube to be blasted and to the blasting lance, and an injector nozzle (11, 11'), which is aligned with the blasting nozzle (7, 7') and is used to form a gaseous curtain which shields the interior of the tube from the penetration of blasting material, is provided. <IMAGE>

Description

The present invention relates to a device for cleaning the surface of a hot-soaked pipe end according to the preamble of the main claim.

When manufacturing pipes that can be screwed together for the oil and gas industry, the wall thickness in the end area must be increased depending on the load in the area of application and the type of thread cut. This is done in a known manner in that a certain length at the end of the tube is hot compressed in an upsetting machine and thereby the wall thickness is increased. The surface condition and the dimensional conditions of the hot-soaked pipe end rarely allow direct thread cutting, so that cleaning and dimensional processing are required beforehand. To do this, the pipes with the upset pipe ends are removed from the production line and fed to a cleaning station. There, the surface scale is roughly removed with a semi-automatic grinding machine and then critical areas are manually repaired with a hand grinding machine and the upset seams are ground away. The upsetting seams arise during the upsetting process in that, for. B. two cooperating compression half-shells are used and part of the material flows into the joint between the two compression half-shells. Another device uses 4 compression half-shells, two of which work together in pairs. It is also known to use an undivided compression sleeve in combination with a pair of compression half-shells. In the latter case, a round seam is also created at the transition from the sleeve to the compression half-shells. These seams are for subsequent dimensional processing on one seam and are for subsequent dimensional processing on one Lathe disturbing, since the undisturbed chip flow is hindered at this point and the impact load leads to increased wear of the tool and the storage of the tool holder is affected. Even if the load on the machine tool is accepted, these seams are nevertheless disruptive, since they lead to a radial offset of the pipe end to be machined in the chuck of the lathe.

The manual cleaning and plastering of a hot-soaked pipe end is cost-intensive due to the personnel expenditure and the surface quality achieved also depends on the subjective judgment of the operator. In addition, depending on the contour of the upsetting, the transition area in the upset pipe end is only partially included in the cleaning. For highly stressed pipe connections, manual grinding also poses a risk, since depending on the quality of the manual grinding work, harmful notches can be formed, which reduce the fatigue strength of the connection.

As an alternative to grinding, the scale can also be removed by blasting. For cleaning the inner surfaces of pipes, it is known (Zeitschrift Bleche, Rohr, Profile 32 (1985) 6, p. 303) to use a rotatable blasting head which is connected to a lance which supplies the gaseous carrier medium, usually compressed air and the blasting material, and on which at least one jet nozzle inclined in the longitudinal plane to the inner surface of the tube is arranged. In the blasting head area, the compressed air and the blasting material are mixed like an injector and directed onto the inner surface of the pipe. This device is not very suitable for cleaning the inner surface of hot-soaked pipe ends, since the rotatable jet heads are very large in size and can no longer be used for smaller inner diameters, and their weight is complicated in terms of weight via a device arranged on the lance have to be supported. Another disadvantage is the fact that the device for supporting the blasting head during the blasting process cannot be adapted to the different inside diameters of a hot-soaked tube end. A further disadvantage is that in the known blasting methods, be it in the manner of free pressure blasting only from one or both ends, or in the manner of a combined pressure-suction blasting, in which underpressure is generated on the opposite end, the Blasting material is distributed throughout the tube and then a complex cleaning process is required to clean the tube accordingly.

The object of the invention is to provide a device for cleaning the surface of a hot tube end by means of radiation, which is suitable for removing the scale on the inner surface of the hot tube end with an inner diameter of 160 mm without an expensive support device and can be adapted to different inner diameters during blasting and in one subsequent cleaning of the blasted pipe is not necessary.

This object is achieved by the characterizing features of the main claim. Advantageous further developments are defined in the subclaims.

The previous manual or semi-automatic grinding, which is only carried out after the last hot forming, is replaced in the method according to the invention by internal and external blasting after each upsetting step. The latter point is essential, since it has been found that there is a risk that sticky scale particles will be pressed into the material during the next upsetting step, especially in the case of upsetting in several steps with several heats. This worsens the initial surface for the subsequent mechanical processing in such a way that the wall thickness addition must be increased to ensure that there are no corresponding defects after the turning.

It is essential in the method according to the invention to record the entire upset tube end area, including the transition. The previously known blasting methods, be it in the type of free pressure blasting only from one or both ends, or in the manner of a combined pressure-suction blasting, in which negative pressure is generated on the opposite end, all have the disadvantage that the blasting material is distributed throughout the pipe and then a complex cleaning process is required to clean the pipe accordingly. This is prevented by the method according to the invention in such a way that the blasting material mixed in an injector-like manner with a carrier medium in the form of a bundled jet is directed onto the inner surface at a predetermined angle in the direction of the insertion end of the tube to be blasted, so that most of the other Reflected from the inside surface of the blasting material is thrown forward towards the insertion end. This means that the blasting material occasionally falls in the direction of the other pipe end cannot get inside the tube, a certain amount of the carrier medium, e.g. B. Compressed air supplied separately and also without mixing with the blasting material directed behind the blasting point on the inner surface, so that a shielding air curtain is formed.

In order to ensure that the entire surface is blasted without gaps, the tube moves in the circumferential and longitudinal directions relative to the blasting during the blasting. This movement can be realized in that either the tube moves in the circumferential and longitudinal directions and the jet device remains stationary or vice versa. In order to optimally match the blasting effect and the effect of throwing away the blasting material reflecting on the inner surface, the exit angle can be adjusted according to the contour of the inner surface to be blasted. This is chosen so that the angle between the axis of the incident beam and the surface line of the inner surface in the direction of the insertion end is always an obtuse angle, i.e. is always greater than 90 degrees. This is of particular importance if the transition area from the compression area to the undeformed pipe is characterized by a conical widening in the direction of the undeformed pipe. In such a case, the angle inclination of this transition area would be the determining variable for the choice of the beam angle. In the subsequent cylindrical compression area, the condition of the obtuse angle for the effect of the blasting material being thrown away is complied with in any case.

Internal and external blasting can be carried out simultaneously or separately and can be integrated as a work step in the production line of hot upsetting. With an appropriate coordination of the cycle sequence, the material flow is thereby improved and accelerated. The removal of the Compression seams can be done by grinding or by blasting. In order that the tool can be optimally positioned, it is further developed to contactlessly record the outer circumferential contour of the compressed pipe end. Since the area of the upset seam means a jump in the contour that changes within a certain bandwidth, this can be used for a conversion into a control signal in order to bring the tool into the optimal working position. This is particularly important in the case of blasting, since the blasting material has to be directed quasi-focused onto the upset seam so that the amount of material accumulated in the upset seam can be removed in a reasonable time or the upset seam increase can be reduced to an acceptable level.

The device for the internal blasting according to the invention consists of a blasting head arranged on a lance with at least one blasting nozzle arranged on the circumference, the axis of which is inclined towards the insertion end of the tube to be blasted. Several nozzles with differently set outlet angles or groups of nozzles can also be arranged. In the case of the nozzle groups, the exit angles are the same within a group, but differ from group to group. A group can consist, for example, of two nozzles arranged offset by 180 degrees, so that the jet head or the tube only has to be pivoted by 180 degrees in order to coat the entire inner surface on the circumference. In the case of a nozzle group consisting of four jet nozzles, only a swivel movement of 90 degrees would be required. This pivoting movement of the jet head has the advantage over a 360 degree rotation that the sealing problems in the feed lines are easier to solve. For a separate feed of the carrier medium, a tube is arranged in the inner hollow body of the blasting head, which tube extends radially to the outside with channels arranged in the area of the front end of the blasting head Connection is established. One of the constructive solutions consists in arranging a disk-like element on the end face of the blasting head, which has a multiplicity of radially extending channels which open into a central bore arranged in the middle, into which the tube extending through the blasting head also opens. For effective shielding, it is advantageous to deflect the carrier medium emerging from the radial channels somewhat in the direction of the insertion end of the tube to be blasted, so that the emerging carrier medium can counteract the blasting material falling backwards. The shielding can also be reinforced in such a way that a flexible, heat-resistant element is releasably attached to the end face, the outer diameter of which is at least equal to or slightly larger than the largest inner diameter of the pipe end. Such an element can be designed in a simple manner as a brush or as a flexible disk. The flexibility of this element must be such that a simple adaptation to the respective contour is possible during the axial back and forth movement of the jet head. In addition, the material of this element must be heat-resistant up to a temperature of approximately 600 degrees Celsius, since the blasting takes place immediately after the upsetting process has ended.

External blasting is carried out in a known manner with a blasting head directed towards the tube end, in which, as already described for internal blasting, a commercially available blasting material such as B. corundum, steel, gravel or wire grain with a carrier medium - usually compressed air is used for this purpose - are mixed like an injector. The required movement in the circumferential direction can be carried out by rotating the tube to be blasted or by pivoting the blasting head around the tube. Here, too, it is advisable to arrange several blasting heads on the circumference when the pipe is at a standstill in order to limit the required swivel angle and thus the sealing problems for the feed lines to keep low. For reasons of noise protection and keeping the adjacent machine systems clean, the entire facility for internal and external blasting is provided with a sound-insulated housing and the passage of the pipe to be blasted z. B. sealed by a rubber sleeve. So that the sensitive measuring apparatus for contactless scanning of the outer contour of the hot-soaked pipe end is not damaged, it is folded away during the blasting and, if necessary, covered accordingly.

The proposed internal blasting device is not only suitable for the method of descaling hot-soaked pipe ends described here, but can generally be used for any type of surface cleaning with limited internal surfaces. It is irrelevant to the process whether it is a matter of removing scale layers or paints or other particles adhering to the surface. It is essential that the part of the hollow body which is not to be cleaned is not soiled by the blasting material in order to avoid subsequent, possibly complex cleaning.

The method and the device are explained in more detail in the drawing.

• Figur 1 eine Prinzipskizze der Verfahrensweise für das Warmanstauchen und die anschließende mechanische Bearbeitung
• Figur 2 einen Längsquerschnitt durch die erfindungsgemäße Innenstrahleinrichtung
• Figur 3 eine schematische Darstellung der berührungslosen Abtastung der äußeren Kontur des angestauchten Rohrendes.

Show it:

• Figure 1 is a schematic diagram of the procedure for hot upsetting and the subsequent mechanical processing
• Figure 2 shows a longitudinal cross section through the internal blasting device according to the invention
• Figure 3 is a schematic representation of the contactless scanning of the outer contour of the upset pipe end.

In Figure 1, the procedure for the hot upsetting and the subsequent mechanical processing is shown in the form of a schematic diagram. The tube 30, the end or ends of which are to be hot-compressed, is first a heating device, for. B. an induction system. In this device the respective end is heated 31 to the forming temperature and then in an upsetting machine in which e.g. Two cooperating compression half-shells are arranged, retracted and compressed 32 while increasing the wall thickness. The descaling system according to the invention is arranged in the production line, to which the tube 33 is fed with the compressed end. The details of part of this descaling system are shown in Figure 2. In this descaling system, the upset tube end is descaled inside and out 34. If several upsetting steps with more heat are required for the final contour of the upset end, the process already described is repeated starting with step 31. The decision switch is symbolized here by a rhombus 35 . If one upsetting step is sufficient or the last upsetting step has ended, either the descaling 34 or subsequently the upsetting seams 40 (see FIG. 3) are removed 36. This step can be carried out on a separate cleaning stand or in the descaling system already described. The pipe with the cleaned pipe ends is then visually checked 37 and mechanically processed and provided with a thread 38 after approval. After completion of this work, there is a threaded pipe 39 which, depending on requirements, is ready for dispatch or is otherwise treated further.

FIG. 2 shows in longitudinal cross section the internal blasting device according to the invention for the descaling of the inner surface of a hot-soaked tube end 1 undeformed pipe can be seen in the right half of the picture. The inner blasting and the outer blasting, not shown here, are carried out either simultaneously or separately after each upsetting step, the contour of a warmly upset tube end being shown after the last upsetting step in this exemplary embodiment. The internal blasting device consists of a the carrier medium, for. B. compressed air and the lance supplying lance with two coaxially arranged hollow bodies 3, 4 which at the end merge into a blasting head 5 which is closed at the end. On the outside of the conical part 6 of the blasting head 5, at least one or more blasting nozzles 7, 7 'are arranged at a fixed angle in the direction of the insertion end 8 of the pipe to be blasted. The two coaxially arranged hollow bodies 3, 4, which are designed as tubes in this exemplary embodiment, form an annular space 9, via which the blasting material is fed. To ensure that the blasting material reaches the area of the blasting nozzle 7,7 ', it may be necessary to put the annular space 9 under slight pressure from the carrier medium. The amount of the carrier medium required for blasting is fed through the bore 10 of the inner hollow body 4 and deflected in the blasting head 5 in the direction of an injector nozzle 11, 11 'arranged on the outside of the inner hollow body 4'. The axes of the jet nozzle 7,7 'and the associated injector 11,11' are aligned with each other, as well as the bore 12,13,13 '. The deflection of the supplied carrier medium takes place through a distributor element 14 rotatably arranged in an extension of the inner hollow body 4. This distributor element 14 has recesses 15 on the side facing the insertion end 8, so that a connection between the bore 10 of the inner hollow body 4 and the injector nozzle 13 or 13 'arises. This makes it possible to control jet nozzles 7,7 'individually or in groups with a differently set outlet angle. The distribution element 14 is rotated by a Tube 16 arranged coaxially in the bore 10 of the internal hollow body 4, which is firmly connected to the distributor element 14 and extends through it. For the front end of the blasting head 5, a cover 16 is attached to the thickened ends of the two hollow bodies 3.4 'with screws 17, 18, which has a bolt-like extension 19 extending into the interior of the tube. On this bolt 19, a disk-like body 20 is fastened, in which radially extending channels 21 are arranged. The cover 16 is provided with a central bore 22 which is aligned with the bore of the centrally arranged tube 16. Compressed air is also fed through this tube 16 via the central bore 22 of the cover 16, which then exits radially from the channels 21 of the disk-shaped body 20 and forms a shielding process. In order to intensify the effect of the shielding, the radial channels 21 of the disk-shaped body 20 are angled at the outlet end in the direction of the insertion end 8, so that the exiting air counteracts the blasting material falling to the rear. For an even better shielding of the interior of the tube from blasting material flying around, in this exemplary embodiment a brush 23 formed from steel wires is arranged on the bolt 19, which brush is pressed onto the disk-shaped body 20 by means of a disk 24 and a nut 25. During the blasting, the blasting head 5 is moved axially back and forth, here marked by the arrows 26, 26 'and at the same time also rotated or only pivoted, here marked by the arrow 27. This movement must be carried out by the brush 23 and it must be in the Diameter at least equal to or slightly larger than the largest inner diameter of the tube end 1, so that the effect of the shield is maintained during the movement. In this example, the largest inside diameter is in the undeformed part of the tube 2, but when widening, it can also lie in the compression area.

As an alternative to the movement of the blasting head described here in the axial and in the circumferential direction, a corresponding movement of the tube is also possible when the blasting head 5 is at a standstill.

Figure 3 shows schematically the non-contact scanning method for locating the upset seams 40. By means of a measuring device 41, z. B. an inductive displacement sensor, the outer contour 42 of the upset tube end 1 (Fig. 2) is scanned without contact. The measurement signals are fed to an amplifier 44 via a line 43 and then converted into digital values via an analog-digital converter 45. These values flow into a computer 46, in which the measured actual data are compared with predetermined target data. In the area of the upset seams 40, there is a deviation in the contour that lies above a predetermined threshold value. From this, the computer determines the control coordinates and feeds them to a control member 47, the control signals of which are sent to a movable tool holder 48. The tool 49, in this case a schematically represented blasting head, is positioned by means of the tool holder 48 and the emerging blasting material can be focused on the upset seams 40 to be removed.

Claims (7)

1.Device for cleaning the surface of a hot-soaked pipe end with at least one blasting nozzle directed at the pipe surface and arranged on a blasting head and a feed connected to the blasting head for a gaseous carrier medium and blasting material which is mixed in the injector-like area in the blasting head area, the device for axially blasting the device has a displaceable jet lance with the jet head arranged thereon and a supporting means and the jet nozzle is aligned in the longitudinal plane at an angle to the inner surface of the tube,
characterized,
that for internal blasting, the blasting lance, which is movable in the circumferential direction (27) and consists of two coaxially arranged hollow bodies (3, 4), forms a compact unit with the blasting head (5) adjoining it, and the blasting nozzle (7, 7 ') under one towards the insertion end (8 ) the pipe to be blasted and the angle set to the blasting lance is arranged and the axial bore (10) of the internal hollow body 84) is connected to a channel extending through the wall of this hollow body (4) in the direction of the insertion end (8), at the end of which an injector nozzle (11, 11 ') aligned with the blasting nozzle (7, 7') is arranged and the axial bore (10) of the internal hollow body (4) forms a gaseous curtain shielding the interior of the tube from penetrating blasting material Has coaxially arranged tube (10) which extends through the blasting head (5) and is distributed over the circumference in the region of the blasting head end arranged, radially extending to the outside channels (21) is connected and a flexible, heat-resistant element is releasably attached to the front of the jet head (5), the outer diameter of which is at least equal to or slightly larger than the largest inner diameter of the pipe end. 2. Device according to claim 1,
characterized,
that the blasting head (5) has a plurality of blasting nozzles distributed over the circumference (7,7 ') and the axial bore (10) of the internal hollow body (4) in the region of the blasting head (5) merges into an extension into which a rotatable distributor element (14) is arranged, through which the pipe (16) lying in the axial bore (10) of the inner hollow body (4) and firmly connected to it extends, and correspondingly on its side facing the insertion end (8) of the pipe to be blasted has shaped recesses (15) which form a connection from the bore (10) of the inner hollow body (4) to the injector nozzle (11, 11 ') in the circumferential direction when the distributor element (14) is in the appropriate position. 3. Device according to claim 2,
characterized,
that the blasting nozzles (7,7 ') form two or more nozzle groups with differently set outlet angles for the blasting material, the outlet angle being the same within one group and by rotating the distributor element (14) the individual nozzle groups with the bore (10) feeding the carrier medium of the inner hollow body (4) can be connected. 4. Device according to claim 1,
characterized,
that the element is in the form of an annular brush (23). 5. Device according to claim 1,
characterized,
that the element has at least one annular disc. 6. A method for descaling and plastering a pipe end hot-soaked by means of a divided tool using a device according to claim 1, in which the surface scale formed and the compression seams are mechanically removed after the hot forming has been completed,
characterized,
that the entire upset tube end area including the transition to the beginning of the undeformed tube is blasted inside and outside after each upsetting process and after the last upsetting process the upsetting seams are removed and when blasting internally a certain amount of the gaseous carrier medium supplied without mixing with the blasting material from the center is directed radially over the entire circumference onto the inner surface, which forms a gaseous curtain which migrates with the radiation source and shields the interior of the tube from the penetrating blasting material. 7. The method according to claim 6,
characterized,
that the inside and outside blasting takes place simultaneously.

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