GB2190023A - Process and apparatus for reconditioning cylindrical parts, tubes or props - Google Patents

Abstract

For the reconditioning of tubes with smooth surface, cylinders or underground mining props a metal sheet 4, which has previously been bevelled at the edges, is laid in strip form on to a machined-down e.g. turned region of the tube 3 and fixed by application of a weld seam into the groove formed between the strips. Then the new surface thus formed is further worked according to the conditions of use and possibly improved by application of a corrosion-proof covering. The apparatus has a combined turning and welding device, the welding lance 6 being preceded in by a guiding feeler 7 which is adaptable to the form and dimensions of the groove. <IMAGE>

Description

SPECIFICATION Process for reconditioning cylindrical parts, tubes and the like The invention relates to a process for reconditioning smooth-surfaced tubes, cylindrical parts, especially props used in underground mining and tunnelling, where the old surface layer is machined down to existing damage and irregularities and then provided with a compensating coating. The invention further relates to an apparatus for processing tubes, cylinders, especially props, with a turning device and a welding device.

Cylindrical tubes and the like articles on which scoring or other damage have formed must be reconditioned at regular intervals if they come into use in connection with seals or the like. Thus byway of example the pistons of props used in underground mining are turned down and then provided with a new welded coating, in orderthen, after appropriate further processing and reconditioning, to be available for renewed use. The welding-on of an appropriate coating is very expensive of material and time and on account ofthe form of the cylindrical tubes the application as such must mostly be effected by hand. It is also known to fit Y-shaped tubes approximately of the thickness of the turned-down layer on to the tubes and pistons, in orderthen to attach them by welding or shrinking in the upper and lower regions.The disadvantages here are the expensive process and the problem that the newly applied coating cannot be included in the stability calculation. Thus reconditioned props and other cylindrical parts are of only limited utility, by reason of the reduced stability. This is of considerable detriment to the entire reconditioning process.

The invention is based upon the problem of simplifying the reconditioning oftubes, cylinders and the like parts and atthesametime making it more precise, while the achievable stability values are comparable with the original ones.

The problem is solved in accordance with the invention in that a metal sheet, having a thickness lying above the machine-away thickness, is bevelled off at the edges, laid in strip form on to the machined-away region and fixed by application of a weld seam into the groove formed between the strips, whereupon the newly formed surface is further worked and if necessary improved.

Thus by this process it is possible in a precisely pre-determined mannerto replace the machined-away material by a sheet namely in such a waythattheconnection betweenthesheet metal and the tube or prop is such that the new sheet, that is the new coating, fully enters the stability calculation.

Thus the reconditioned part can be used again atthe same point, that is for example the pit prop can be used again underground, and precisely in the stability range in which it was previously used. Since the weld seam to be applied is precisely pre-determined by the pre-determined groove, automatic devices can be used, which makes the working process substantially easier and cheaper, but at the same time also more precise, so thatthe reconditioning as a whole is improved. Above all, preciseworkinginturning is no longerthe important point, since subsequently the new surface is formed by the metal sheet, which is laid in protective manner upon the basis, without the latter being taken forthe stability of the surface coating.The width of the sheet metal strip can be selected according to the individual case, so that correspondingly many orfew weld seams must be drawn. Furthermore the metal sheet or sheet metal strips presents or present an exactly calculable surface for the reprocessing, which is optimally available both as regards material and as regards quality for improvement.

According to an expedient development ofthe invention it is provided that the metal sheet is cut in spiral form, bevelled at the edges and then laid in spiral form around the cylinder or partto be reconditioned. This procedure results in optimum loading both of the connection between metal sheet and base and of the applied sheet metal connected with the base only at individual points. Since for example the prop is loaded only by way of the seal in extension and retraction, thus an optimum surface is achievable, and at the same time, with regard to forces acting from the exterior, due to the appropriate dimensioning of the metal sheet and the previous material removal, again a very resistant surface can be achieved.

According to afurtherdevelopmentofthe invention the metal sheet is cut into strips which cover only a part zone of the part to be reconditioned, bevelled at the edges and further worked. Thus the sheets are arranged with parallel axes and connected by way of the weld seams, and this process too advantageously offers the possibility of automation.

In order to facilitate further processing it is provided that corrosion-proof, preferably VA sheet metal, is cut into spiral form or into narrow sheet metal strips and further worked. According to the intended use, a special coating of the applied sheet metal becomes superfluous, so that the entire process can be shortened and simplified. Such sheet metal furthermore has advantages of strength, so that the service lives can be substantially lengthened.

According to another variant ofthe process according to the invention it is provided that the sheet metal in spiral or strip form after after-treatment is provided with a corrosion-proof covering. This is advantageous especially when special demands are made of the corrosion-proof covering and when, specifically in the case of cylinders, the most uniformly smooth surface possible is necessary. In an advantageous manner it is peruse entirely immaterial forthe process how the after-treatmenttakes place, finally this can take place in one or more part steps, according to what demands are to be made of the workpiece.Thus in every case it is possible to produce the required condition for the reuse ofthe cylindrical parts and otherworkpieces, without this having disadvantageous effects upon the stability.

In orderthatthe widest possible strips may be used, but on the other hand to achieve their fixing at a plurality of points, it can be expedient to provide the sheet, cut into strips, with apertures over the length which then serve for welding by points. These apertures can be punched from the outset into the sheets and are filled with welding material, and they should expediently have a rectangularform in order to guarantee a linear connection. Even under heavy loadings thus a comprehensively secure connection is guaranteed between the sheet and the region of the workpiece lying therebeneath.

In orderto guarantee the most favourable possible loading ofthe applied sheets, according to a further development of the invention it is provided thatthe weld seam is applied in each case at an angle, preferably at right angles to the main direction of loading.

An apparatus comprising a combined turning and welding device serves for carrying out the process according to the invention. By this combination it is possible practically in one operation both to remove the damaged layerfrom the workpiece and immediately thereafter to apply the new layer again.

Theturning and welding devicesworkin a specific working cadence, so thatthethroughput of such devices can be very high. It is here provided according to the invention thatwith the welding device there is associated a feeler which is made adaptable to the dimensions and form of the groove pre-determined bythe metal sheet and to control the welding device accordingly. In this mannerthe entire process can be automated because a guide device is producedforthefollowingwelding device by means ofthe separatelyformed groove and the feeler guidedthereon,which ensures the precise application of the weld seam in every case.

In accordance with the invention sheet metal shears preceding the welding device should be provided between the turning device and the welding device, and are made adjustable, providing an oblique cut By means of these sheet metal shears the necessary obliquity is produced on the edges of the metal sheet, producing a groove optimum for the existing conditions in each case, this groove serving as guide both for the feeler and for the subsequent lading device, for the application of a precisely defined weld seam acting in a precise and directed manner.

For the securing ofthe metal sheet at a plurality of points, seen over the circumference, and additionallyforthe weld seam it is advantageous if the metal sheet is formed having window-type apertures in distribution overthe length. Here again with the aid ofthe same feeler or of a separate feeler practically simultaneously with the application ofthe weld seam into the produced groove the desired connection between metal sheet and base can be achieved in the apertures by means ofthe welding device.

The process and device according to the invention are especially distinguished in thatthey are suitable both forthe reconditioning oftubes, props and the likeworkpiecesandforthe production of corresponding newworkpieces. In new production the process and the apparatus according to the invention have the advantage that expensive improvementoftheentireworkpiece is not necessary, but that an already pre-improved metal sheet can be applied upon workpieces which merely provide the stability values and then is only deliberatelyfurtherworked.In reconditioning it is essential that a process and an apparatus are produced which guarantee that the original stability values are again achieved, or at least achieved to such extent that the treated workpieces can be used and applied as before. Furthermore it is advantageous that the entire process takes its course very precisely and can be automated to such extent that high values and uniform values are achieved as regards the end quality.

Further details and advantages of the object of the invention appearfrom the following description of the accompanying drawing, in which a preferred example of embodiment is represented with the necessary details and individual parts, and wherein : Figure 1 shows a diagrammatic representation of a machined cylinder with metal sheet applied in spiral form, Figure2 shows a diagrammatic representation of a cylinder with metal sheet extending straight in strip form and Figure3shows a diagrammatically represented apparatus for working upon cylinders.

The cylinders 3 as reproduced in Figures 1 and 2 have been treated in the combined welding and turning device 1,2 visible from Figure 3. While in the formation asvisiblefrom Figure 1 the metal sheet4 is applied in spiral form, according to Figure2 a longitudinally extending metal sheet 4 is applied. In each case the metal sheets joined to one another comprise, orthe spirally extending sheet4 comprises edges (11,12) bevel led off so far that a groove 5 is produced between the edges. Through the welding lance 6, which is guided by the feeler 7,a weld seam is applied in directed manner into this groove 5 and guarantees an intimate connection of the metal sheet4withthe base, that is with the cylinder 3.

In addition apertures 8,9 can be provided in distribution over the length ofthe sheet metal strips 10, into which apertures welding material is likewise introduced in orderthere also again to achieve a directed connection between metal sheet 4 or sheet metal strips 10 and the cylinder 3.

Figure 3 further makes it clearthatthe feeler 7 is arranged in each case leading the welding lance 6, and this feeler 7 engages in the groove 5 and thus constitutes a directed guidance ofthefollowing welding lance 6.

Claims (12)

1. Process for reconditioning smooth-surfaced tubes, cylindrical parts, especially props used in underground mining and tunnelling, where the old surface layer is turned down as far as existing damage and irregularities and then provided with a compensating coating, characterised in that a metal sheet having a thickness lying above the turned-down thickness is bevelled off at the edges, laid in strip form on to the turned-down region and fixed by application of a weld seam into the groove formed between the strips.

2. Process according to Claim 1, characterised in that the metal sheet is cut into spiral form, bevelled at the edges and then laid in spiral form around the cylinder or partto be reconditioned.

3. Process according to Claim 1, characterised in that the metal sheet is cut into strips covering only a partial region ofthe part to be reconditioned, bevelled at the edges and further worked.

4. Process according to Claim 1, characterised in that corrosion-proof, preferably VA sheet is cut into spiral form or into narrow sheet metal strips and further worked.

5. Process according to Claim 1, characterised in that the sheet metal in spiral or strip form, afterthe after-treatment, is provided with a corrosion-proof covering.

6. Process according to Claim 1 and Claim 3, characterised in that the metal sheet cut into strips is provided over the length with apertures serving for welding by points.

7. Process according to Claim 1 oroneormoreof the following Claims, characterised in that the weld seam is applied in each case atan angle, preferably atrightanglestothe main direction of loading.

8. Apparatus for processing tubes, cylinders, preferably props with a turning device and a welding device and thus for carrying out the process according to any of Claims 1 to 7, characterised in that with the welding device there is associated a feeler (7) which is made adaptable to the dimensions and form ofthe groove (S) pre-determined by the metal sheet (4) and to control the welding device correspondingly.

9. Apparatus according to Claim 8, characterised in thatthewelding device (1 ) is preceded by sheet metal shears which are formed adjustably, producing an oblique cut.

10. Apparatus according to Claim 8, characterised in that the metal sheet (4) is formed having window-like apertures (8, 9) in distribution over the length.

11. A process for reconditioning smooth surface Wiles substantially as described with reference to Figure 1 or Figure 2 ofthe accompanying drawings.

12. Apparatus for processing tubes substantially as described with reference to Figure 3 ofthe accompanying drawings.