EP0065533B1 - Method for rolling a u-shaped steel bar or similar and beam-making universal mill train for implementing such method - Google Patents

Description

The invention relates to a method for rolling U-steel or the like. From a U-shaped pre-profile in a universal carrier line, which comprises at least one compression frame, in which a pre-profile is assumed that is only on the outside of the web in the central area straight and in the adjoining transition areas of the flanges has slants, which form an obtuse angle with the straight line of the middle area, and in which the overfills or bulges arising in universal stitches at the free end areas of the flange edges and the respectively opposite transition areas between the web and flanges in at least one compression stitch with the web of the rolled profile stretched.

Such a procedure is known from DE-OS 2 420 408, which shows the difficulties that arise when a U-steel is to be rolled in a universal carrier line, because U-steel, in contrast to double-T, Beams or H-steel has an asymmetrical cross section with respect to the web. When rolling U-steel in universal stands, particularly large inaccuracies can occur, which are caused by different stretching of the rolling stock. In particular with increasing U-steel dimensions, which is synonymous with larger flanges and thus increased asymmetry, bends occur which lead to faults such as breaks and cracks when the rolling stock moves or cracks when the rolling stock is pushed into a caliber. According to DE-OS 2 420 408, these difficulties are to be remedied by selected, unequal circumferential speeds of the upper and lower rollers.

The invention is based on the same object, namely the provision of a method for suppressing bending of the rolling stock and for suppressing an imbalance in the power distribution between the top roller and the bottom roller of the compression stand when rolling U-steel using a universal roller train, but the solution is one other. By also starting from a preliminary profile in the method according to the invention, which has bevels in the transition areas of the flanges, in whose area bulges appear in universal passes, which are rolled in upsetting passes while stretching the web of the rolled profile, the solution according to the invention provides that the middle straight area of the outside of the web from which the bevels originate is dimensioned equal to or a few millimeters smaller than the web width of the finished profile when the preliminary profile is rolled, that the obtuse angle a of the inclines of the preliminary profile is not less than 130 ° that the contour of the outside of the web in the upsetting stitches is maintained by shortening the bevels in previous universal stitches until the bevels are used up in a universal stretching stitch and the bulges fill a U-shaped intermediate profile that is angular in the transition areas and that the intermediate profile is as known t is finish-rolled in a universal stand, possibly after previous universal stretching passes in closed calibers and upsetting passes.

The invention initially differs in terms of the design rules for the production of the preliminary profile from the models according to FIGS. 5 and 6 of DE-A 2 420 408, because here the middle straight area of the outside of the web is significantly smaller than the web widths of the finished profiles shown. as well as the obtuse angle that the bevels form with the middle straight region is over 130 °. These two design rules are decisive for the solution of the task within the scope of the further process features. The adjustment of the middle straight web area of the preliminary profile ensures that when the bevels in the universal stretching stitches are shortened, a web width that ultimately corresponds to the finished profile is set in an intermediate profile, so that rolling can then continue with closed calibers. The requirement that the inclination of the bevels should not be greater than the obtuse angle between the bevels and the straight central area and to maintain this contour in the upset stitches means that the universal stretch stitches do not involve too much material at the expense of stretching in the spreading or the bulges in the area of the bevels goes with which these bulges never go beyond the edge areas of the horizontal roller of the universal stand or the universal stands assigned to the web outside (in the case of continuous operation) when the universal calibers are still open.

The method according to the invention therefore leads to the fact that the restoration of the not too steep inclines in the transition area between the web and the flanges exerts a supporting force counteracting the flow of the material from the flanges in the upsetting stitches, so that in the upsetting stitches a substantial stretching of the profile without essential Spreading takes place. In each universal stitch, in turn, with strong decreases in the web as well as in the flanges, the formation of bulges in the area of the bevels can be tolerated, because these are ironed out again in a subsequent upsetting stitch. When the bevels are used up in a universal stretch stitch, i.e. The bulges created during this pass fill an angular U-shaped intermediate profile in the transition areas can be transferred to the ideal universal rolling in closed calibres for further acceptances, provided that it is not possible to finish-roll immediately after the intermediate profile.

With regard to the prior art, reference is also made to US Pat. No. 3,538,732 and US Pat. No. 1,856,269. Although a method for producing U-steel is described in US Pat. No. 3,538,732, in which bevels are restored in upsetting stitches after universal stitches on the edge regions of the web outside of intermediate profiles, it is not assumed that a preliminary profile that these bevels already has, so in Universal stitches with an open caliber, the spread can go unhindered in overfills of the open caliber, which is at the expense of stretching. This method therefore requires more stitches than the method according to the invention, especially since there is no stretching in the web area in the upsetting stitches. In another embodiment of the known method according to the first-mentioned document, overfills are avoided from the outset by starting with closed calibres in the universal frame. Then the bale length of the horizontal roller of the universal stand, which processes the outside of the U-profile, must correspond to the width of the preliminary profile, or vice versa (column 5, lines 15 ff), and the flange thickness of the preliminary profile must not be too great should, if possible, correspond to the finished thickness (column 5, line 54 ff). Although it is in accordance with the invention that only slightly inclined bevels are formed in the upset stitches and closed calibers are used, this known method requires many stitches in the roughing pass to produce the preliminary profile, whereby no strong universal stretching stitches may be carried out, since then in Too much upsetting work would have to be done on the flanges on the flanges, which is incompatible with not having to stretch the web in the upsetting stitches.

Although the process according to US-A 1,856,269 starts from a preliminary section with lateral bevels opposite to a straight central region form an obtuse angle of slightly more than 130 ^0, however, here the middle one straight portion substantially smaller than that of the Finished profile.

In accordance with the invention, a universal stand with an open caliber and an additional stand with two profiled horizontal rolls are used for the rolling out of the preliminary profile in reversing operation, in order to roll U-shaped intermediate profiles while shortening the bevels and while maintaining the contour of the outside of the web. This contour, however, includes cusps in the transition between the straight middle bar area and the bevels, which are still present when the caliber is closed on a universal scaffold. This process therefore requires two further duo roll stands with closed calibres to produce the finished profile and is therefore not comparable with the process according to the invention, which only requires one universal stand and one compression stand until the last intermediate profile for reversing operation. Incidentally, the procedure known from US Pat. No. 1,856,269 for congruently restoring bevels of a preliminary profile after each universal stitch with overfilling in a duo stitch when rolling U-steel has not continued in the further development of this technique, as the others dealt with References show, because the latest reference DE-A 2 420 408 lacks any reference to the meaning of bevels on the preliminary profile.

The method according to the invention can of course be implemented in continuous operation with the corresponding outlay of universal and upsetting stands, the rollers of all stands being fixed. The last universal frameworks must then be set up to form closed calibres, i.e. the vertical rollers must be able to enter between horizontal rollers.

A universal carrier line for performing the process in reversing operation, on the other hand, only comprises a universal stand with adjustable rollers and only an upsetting stand with adjustable profiled horizontal rollers in tandem arrangement, as well as a universal finishing stand at a distance that enables the rolled stock to run freely after the last upsetting stitch.

This arrangement is known per se. In order to carry out the method according to the invention, however, the horizontal roller of the compression frame, preferably the lower roller, assigned to the outside of the preliminary profile has a profile which is congruent with the contour of the outside, including the bevels, which may be indicated by US Pat. No. 1,856,269. Furthermore, the horizontal roll of the universal stand, preferably also the lower roll, assigned to the web outside should be fixed and determine the height of the rolling line, and ultimately the roll bales of the vertical rolls of this universal stand should be able to overlap the bale length of the fixed horizontal roll, which is the result of US-A 3 539 732.

• Fig. 1 eine schematische Darstellung einer Gerüstanordnung zum Walzen von U-Stahl auf einer Universal-Trägerstrasse im Reversierbetrieb,
• Fig. 2 den Querschnitt des aus einem Vorgerüst austretenden Vorprofils mit den erfindungsgemässen Schrägen,
• Fig. 3 schematisch die Walzenanordnung eines Universalgerüstes mit der erfindungsgemässen Ausbildung der Vertikalwalzen,
• Fig. 4 schematisch die Walzenanordnung eines Stauchgerüstes mit der erfindungsgemässen Kontur der unteren Walze,
• Fig. 5 bis 7 einige Arbeitsstufen im Universal-Vorgerüst bzw. im Stauchgerüst während der stichweisen Bearbeitung des Vorprofils, wobei der rechte Teil der Figuren jeweils die Herstellung von parallelflanschigem U-Stahl wiedergibt, und
• Fig. 8 den Fertigstich im Universal-Fertiggerüst, dargestellt für einen parallelflanschigen U-Stahl.

An embodiment of the invention is explained with reference to the drawings. It shows

• 1 is a schematic representation of a stand arrangement for rolling U-steel on a universal carrier line in reversing operation,
• 2 shows the cross section of the preliminary profile emerging from a roughing stand with the bevels according to the invention,
• 3 schematically shows the roll arrangement of a universal stand with the design of the vertical rolls according to the invention,
• 4 shows schematically the roller arrangement of an upsetting stand with the contour of the lower roller according to the invention,
• 5 to 7 some working stages in the universal roughing stand or in the edging stand during the stitch processing of the roughing profile, the right part of the figures in each case representing the production of parallel-flange U-steel, and
• Fig. 8 shows the finish stitch in the universal finishing stand, shown for a parallel-flanged U-steel.

An example of a reversible universal carrier line is shown in FIG. 1. The roughing stand 1 is followed at some distance by a stand combination consisting of a universal stand 2 and an upsetting stand 3 in a tandem arrangement. This scaffolding combination is followed by a universal finishing scaffold 4 at a distance from the free outlet of the last intermediate profile.

The preliminary profile emerging from the roughing stand 1 is shaped (FIG. 2) in such a way that it deviates in the transition region below the flanges 6 on the underside 7a of the web 7 from the surface which is still straight in the central region M of the web 7 and is formed with bevels 8 . 2 can also be used the other way round if it is intended to roll with flanges directed downwards. About that In addition, the method can also be carried out if, instead of the bevels 8, the preliminary profile has radii in the transition regions, the radii being booked out with the first universal stitch in order to be subsequently pressed by the lower upsetting roller 15 provided with bevels 17 (FIG. 4) to be returned to a profile with slants.

Fig. 3 shows how the preliminary profile 5 is processed by the rollers of the universal stand 2. For this purpose, the preliminary profile 5 lies with its central web area M on the fixed lower roller 11. The upper adjustable horizontal roller 12 engages between the flanges 6 of the preliminary section, so that the web 7 between the upper and lower rollers 12, 11 is completely fixed. The adjustable vertical rollers 13 are directed from the outer sides against the flanges 6 of the preliminary section 5. The vertical rolls are designed such that their diameter is changed approximately at the level of the rolling line W and there has a shoulder 14. As a result, the vertical rolls 13 can overlap the roll bale of the lower roll 11 in the course of the further work stages if the thickness of the flanges 6 is progressively reduced, e.g. except for dimension B of an intermediate profile in FIG. 6.

After both the web 7 and the flanges 6 have been reduced in a universal stitch, the preliminary profile 5 arrives in the compression frame 3, where the flange edges are processed by means of the compression rollers. 4 shows the guidance of the preliminary profile 5 between the upsetting rollers 15, 16 of the upsetting frame (not shown in more detail). In the upsetting stand 3, the upper roller 16 can be adjusted, while the lower roller 15 is again arranged to be stationary. The lower upsetting roller 15 has the same contour as that of the underside of the web 7 of the preliminary profile according to FIG. 2, i.e. above all that the upsetting roller 15 is also equipped with bevels 17 which are congruent with the bevels 8 of the preliminary profile. A bulge 8a (FIG. 3), which formed during the previous rolling in the universal stand 2 as an “overfill” due to free spreading, can thus be rolled away again with each upsetting process. The adjustable upsetting roller 16 dips with a collar 16a between the flanges 6 of the preliminary profile 5, and other part of the upsetting roller 16 presses on the edges of the flanges 6.

It is of course possible that when rolling parallel-flanged U-steel, the horizontal or vetical rollers 11 or 12, 13, which are designed with inclined contours in FIGS. 3 and 4, and the collar 16a of the upper upsetting roller 16, which is also inclined, are straight 5, as shown alternatively with FIGS. 5 to the right half of the figures.

In the upsetting frame 3, the preliminary profile 5 is e.g. after the first universal stitch reversed upset by two stitches. Then the U-profile comes back into the universal stand 2, where a further reduction in the pre-profile is achieved with two further universal passes, because with each pass the rollers are readjusted according to the acceptance of the rolling stock. 5 illustrates the reduction in the profile 5 which has already been achieved after the third universal stitch. The vertical rollers 13 begin at this stage to overlap the fixed lower roller 11 due to the shoulders 14. The slopes 8 of the preliminary profile are almost completely used up, i.e. the bulges 8a of these stitches fill the intermediate profile according to FIG. 5 in the edge area.

This is followed by further upsetting and universal machining processes, the exact number of stitches, i.e. the number of passes of the preliminary section through the universal stand 2 and through the edging stand 3 can be different depending on the preliminary section. 6, e.g. the last passage of the U-steel through the universal frame 2 is shown. The web 7 and the flanges 6 of the U steel have almost the desired dimensions and the desired final shape. The vertical rollers 13 extend far beyond the lower roller 11 with the projecting roller bales. It can be seen that a closed rolling of the U-steel is guaranteed.

The last upsetting stitch (FIG. 7) essentially causes the flange edges to be machined again and any burrs to be removed from the web edges of the U-steel which are rolled away from the bevels 17 of the lower upsetting roller 15. This is particularly the case when the middle straight region M of the preliminary profile according to FIG. 2 and, accordingly, the congruent contour of the lower upsetting roller 15 is chosen to be a few millimeters smaller than the web width of the finished profile according to FIG. 8. The U-steel then becomes punctured into the universal finishing stand 4 and, as shown in FIG. 8 for a parallel-flanged U-steel, receives its finished profile 5 '.

Claims (2)

1. A method for rolling steel channels of the like from a U-shaped preliminary profile (5) on a universal girder rolling mill comprising at least one edging stand (3) which preliminary profile is straight along the central area (M) on the outer face (7a) of the web (7) only, but bevelled in the adjoining transition zones of its flanges (6) to form bevels (8) at an obtuse angle (a) with the straight line of the central area, rolling in at least one edging pass the overfills or bulges (8a) formed during universal passes, at the free ends of the flange edges, and the opposing transition areas between the web (7) and the flanges (6) to stretch the web and roll down the bulges of the rolled profile, characterized in that the straight central area (M) on the outerface of the web (7) of the preliminary profile (5), from which the bevels (8) go out, is equal to or some millimeters smaller than the width of the web of the finished profile (Fig. 8) the obtuse angle (a) of the bevels of the preliminary profile is not less than 130°C, maintaining the contour of the face of the web during the edging pass or passes (Fig. 4) while shortening the bevels (8) formed in preceding universal passes, until the bevels disappear in a universal stretching pass and the bulges (8a) fill a U-shaped intermediate profile which is angular at the transition areas (Fig. 5), and in that the intermediate profile - as known per se - is given a finished shape in a universal mill (4) in closed calibers (Fig. 6) and in edging passes (Fig. 7), if need be after preceding universal stretching passes.

2. Universal girder rolling mill for carrying out the method according to claim 1 in a reversing operation, comprising a universal roll stand (2) with adjustable rolls, an edging stand (3) with adjustable, profiled, horizontal rolls (15, 16), and a universal finishing stand (4), characterized in that the horizontal roll associated with the outer face (7a) of the web (7) of the preliminary profile (5), especially the lower roll (15) of the edging stand (3) is provided with a profile covering the contour of the outer face including the bevels (8), in that the horizontal roll (11 ) of the reversing universal roll stand associated with the outer face of the preliminary profile (5), especially the lower roll, is stationary and setting the high of the roll line (W), and in that the shoulders of the vertical rolls (13) of this universal roll stand allow to overlap the camber length of the stationary horizontal roll (11

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