Tag Archives: leveling

Maschinenbau

Steel Dynamics to revamp push-pull pickle line with Umlauf Bridles

High strip tension for effective stretch-leveling: SDI“s push-pull pickle line in Columbus will be the first in the world to operate with three Umlauf Bridles

Steel Dynamics to revamp push-pull pickle line with Umlauf Bridles

During stretch-leveling, the two Umlauf Bridles apply strip tension forces of up to 1,250 kN.

BTU Bridle Technology has received an order from SES Engineering LLC covering the design, construction and supply of three Umlauf Bridles for a revamp of a push-pull pickle line operated by Steel Dynamics Flat Roll Group (SDI). After the revamp that pickle line will be the first in the world to use exclusively Umlauf Bridles to transport the strip through the line. Umlauf Bridles build up strip tension high enough to ensure that also thick-gage and high-strength strip will leave the pickling line leveled. Once revamped, the pickle line will be able to operate at much higher speeds than before, as scale breaking will be much more intensive.

SDI expects from the pickling line revamp in Columbus/Mississippi, for which SES acts as general contractor, above all a solution capable of producing very high strip tension in the line. Therefore SES chose the Umlauf Bridle technology from BTU. Thanks to their special design, Umlauf Bridles of the latest 3.0 generation are able to apply much higher forces onto strip in processing lines than conventional bridle roll units. What is more, Umlauf Bridles distribute the strip tension extremely uniformly across the complete width of the strip.

The first of the three Umlauf Bridles will be arranged directly behind the pay-off reel. There it will immediately bite the very first centimeters of the head of the up to 13 mm thick and up to 1,880 mm wide strips and guide them into the stretch-leveler. The stretch-leveler will be supplied by SES. In connection with the second Umlauf Bridle arranged behind the leveler, strip tensions of up to 1,250 kN can be reached during stretch-leveling. A very intensive scale breaking effect will result from the thus achieved elongation rates of 0.5 to 1.0 percent. This will make it possible to operate the line at speeds of up to 150 m/min.

As the strip is actively pulled through the leveler by the Umlauf Bridle, no roller drive equipment is required in the leveler. This reduces investment and maintenance costs and prevents roller slipping.

The second Umlauf Bridle pushes the leveled strip into the pickling tank, and the third one will be arranged at the run-out to bite the head of the pickled strip and guide it into the recoiler. At the same time, it creates the strip tension needed to produce exactly wound coils.

Daniel Cullen, Senior Sales Manager of SES Engineering, explains the reasons for choosing the Umlauf Bridle technology: „The most important aspect for us was to find a technology that would be able to reach very high strip tension and allow us to control that strip tension in a very precise way. Apart from that, the simplicity of the Umlauf principle convinced us: we will be able to set the right strip tension exactly where in the line we need it – without any conventional bridle rolls, driven rollers in the leveler or an additional braking unit. Moreover, in future stretch-leveling will require less strain energy as there is no bending of strip in the Umlauf Bridles.“

According to Michael Umlauf, Commercial Manager of BTU Bridle Technology, by moving the strip exclusively in a linear way the Umlauf Bridles are superior to bridle rolls in several respects: „Using Umlauf Bridles in connection with stretch-levelers means that leveling is performed primarily by stretching and only to a minor degree by bending. Actually, up to 90 percent of the leveling work comes from the stretching effect.“

The pickle line is scheduled to come back on stream after the revamp in January 2019.

Background: The Umlauf principle

Umlauf Bridles consist of two crawler-type units covered with an elastic coating. One unit is arranged above and one below the strip. They guide and transport the strip linearly, i.e. without any deflection, at different positions within strip processing lines. Thanks to their extreme compactness, they can be arranged at virtually any position in the line.

By applying the force over an area – and not concentrated in one point – any local concentrations of forces or relative movements between the crawler unit and the strip surface are prevented. Therefore, the risk of surface damage is ruled out, making this technology highly suitable for delicate strip surfaces.

A single Bridle unit may be used to apply large forces to the strip, for example, in order to pull it through side trimmers, slitting shears or levelers. This aspect is of particular interest especially when processing thick strips. The unit may also be installed to decouple the strip tension of a line section from upstream processes or even reduce the strip tension to „zero“. By reducing strip back-tension to „zero“, an Umlauf Bridle makes it possible, for example, to measure the flatness of the strip without any interfering effects.

As the Umlauf Bridles are arranged within the strip processing line, they build up strip tension before the coiler bites the strip head. This significantly increases the usable coil length, in other words the yield. In certain strip processing lines this may lead to a plus of 20 meters per coil.

Umlauf Bridles can be rotated very precisely through their vertical axis, for example, in order to reduce strip camber during leveling or adjust the strip position during side trimming. At cut-to-length lines, they position the strip edge perfectly perpendicular to the shear. The advantages of this solution: perfectly rectangular cut-to-length strip.

About BTU Bridle Technology

BTU was founded in 1985 by Norbert Umlauf who had developed a technology capable of flexibly building up or reducing the back-tension of strip in strip processing lines while adjusting strip travel in a highly precise manner. That technology helped operators of cold rolling mills, strip processing lines and steel service centers to increase the efficiency and flexibility of their operations.

Umlauf Bridles have been in use all over the world at leading producers of steel or NF metals strip. Umlauf Bridles have proven their worth in pickling, hot-dip galvanizing and annealing lines as well as in finishing facilities such as cut-to-length or slitting lines. More than 30 units are in use worldwide. Several new installations are currently underway.

Since 2016, Norbert Umlauf“s sons, Christian and Michael, have taken up active roles in the company, which today is based in Hagen, Germany.

Company-Contact
BTU Bridle Technology GmbH & Co. KG
Christian Umlauf
Sedanstraße 41
58089 Hagen / Germany
Phone: +49 2331.34008-00
Fax: +49 2331.34008-02
E-Mail: christian-umlauf@btu-bridle.de
Url: http://www.btu-bridle.de

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VIP-Kommunikation
Regina Reinhardt
Dennewartstraße 25-27
52068 Aachen / Germany
Phone: +49.241.89468-24
Fax: +49.241.89468-44
E-Mail: reinhardt@vip-kommunikation.de
Url: http://www.vip-kommunikation.de

Maschinenbau

BTU: Exact setting of strip back-tension – at any position in the processing line

Umlauf Bridles can build up very high back-tension in strip processing lines – even when dealing with thick gages and high-strength grades.

BTU: Exact setting of strip back-tension - at any position in the processing line

Two Umlauf Bridles arranged up and downstream of a stretch-leveler can build up any back-tension

Umlauf Bridles designed by BTU Bridle Technology GmbH can be installed at virtually any position of strip processing lines where they ensure gentle strip transport without any deflection of the strip. Umlauf Bridles can build up strip back-tension exactly where and as high as needed. Also thick strips or strips made of high-strength materials can be handled with ease. The Bridle units have proven highly successful in numerous strip processing applications, such as in pickling, annealing, rolling, side trimming, galvanizing and leveling or, in steel service centers, in slitting or cut-to-length lines.

The Umlauf Bridles“ capabilities are not limited to building up or reducing strip back-tension. They are also employed to decrease residual stresses in the strip, optimize strip flatness and correct rolling effects such as camber. Moreover, they minimize cropping scrap at the head and tail ends as well as side trimmings. The crawler-type Bridle units transport the strip in a most gentle manner without any risk of strip surface damage as their contact surfaces come with an elastic coating.

Michael Umlauf, Commercial Manager of BTU Bridle Technology, sees clear cost advantages for his customers: „Operators of strip processing lines may use our Bridle units at virtually any position of their lines to build up or reduce back-tension in a highly controlled way. Our Bridles provide numerous possibilities to operate strip processing equipment in a most efficient way. As a result, more sellable meters are obtained from every coil.“

Leveling without rollers

In conventional leveling arrangements, the forces required to push the strip forward are almost exclusively generated by the leveler. A disadvantage of such arrangement is the risk of roller slippage which may result in longitudinal scratches on the strip surface. What is more, the drives of leveling rollers are often not powerful enough to handle thicker gage strip or universal shafts may break due to local overloading.

If an Umlauf Bridle is arranged behind the leveler, the strip can be pulled through the leveler in a controlled manner, relieving a major part of the load from the drives of the leveling rollers. The effect of the Bridle unit may even be so high that some of the leveling rollers can be dispensed with or regular drives can be replaced by auxiliary ones. Under certain conditions, it may even be possible to do entirely without driven rollers. The Umlauf Bridles can build up back-tensions high enough to also level thick strips and strip made of high-strength steels. Any damage of the strip surface is ruled out because neither the leveling rollers nor the crawler tracks of the Umlauf Bridle will slip on the strip.

An even greater effect can be achieved by combining two Umlauf Bridles in one application. With one unit arranged before and one behind the leveler, it is possible to apply – in a precisely controlled manner – a longitudinally acting force of several thousand kN on the strip. Through this arrangement, leveling is performed primarily by stretching and only to a minor degree by bending. Actually, stretching may take over up to 90% of the leveling work. It may also be possible to use larger rollers in the leveler, resulting in a marked reduction of residual stresses and hence improved flatness of the strip. Due to the high strip back-tension of up to 6,000 kN achievable by the Umlauf Bridle, it has eventually become possible to continuously stretch-level strip without requiring any leveling rollers. Calculations have shown that this is not only much more economical than conventional stretch-leveling. It also provides a better result.

Scale breaking without conventional bridle rolls

For scale breaking and strip leveling ahead of pickling lines, Umlauf units can be used instead of conventional bridle rolls.

As the Umlauf Bridles guide the strip linearly, i.e. without any deflection, no strain energy is required. This is an important cost factor, especially when dealing with thick strips. Additionally, the tensile strength distribution is more homogeneous as the Umlauf Bridle applies the tensile force uniformly over the entire width of the strip.

Norbert Umlauf, founder and Managing Director of BTU explains: „We installed two Umlauf Bridles in a leveling line in which high-strength steel strip of premium quality in terms of shape and flatness is produced. In that application, our Bridle units build up a strip back-tension of 1,200 kN and adjust the elongation rate with an accuracy of 0.1 percent. The equipment, designed for strips of up to about 4 mm thickness, also reduces strip camber in the process. Additionally, we measure the flatness of the strip in a tension-free state during the running process.“

Background: The principle of the Umlauf technology – more sellable meters per coil

Umlauf Bridles consist of two crawler-type units covered by an elastic coating. One unit is arranged above and one below the strip. They guide and transport the strip linearly, i.e. without any deflection, at different stages of strip processing lines. Thanks to their extreme compactness, they can be arranged at virtually any position in the line.

By applying the force over an area – and not concentrated in one point – any local concentrations of forces or relative movements between the crawler unit and the strip surface are avoided. Therefore, surface damage is ruled out, making this technology highly suitable for delicate strip surfaces.

A single Bridle unit may be used to apply large forces to the strip, for example, in order to pull it through side trimmers or levelers. This aspect is of particular interest especially when processing thick strips. The unit may also be installed to decouple the back-tension of a line section from upstream processes or even reduce the back-tension to „zero“. By reducing strip back-tension to „zero“, an Umlauf Bridle makes it possible, for example, to measure the flatness of the strip without any interfering effects.

As the Umlauf Bridles are arranged within the strip processing line, they build up strip back-tension before the coiler bites the strip head. This significantly increases the usable coil length, in some strip processing lines the yield per coil may be increased by up to 20 m.

The Bridle units may be swiveled through their vertical axis, for example, in order to reduce strip camber and adjust the strip position during side trimming. At cut-to-length lines, they position the strip edge perfectly perpendicular to the shear. The result is an exact, rectangular cut.

About BTU Bridle Technology

BTU was founded in 1985 by Norbert Umlauf who had developed a technology capable of flexibly building up or reducing the back-tension of strip in strip processing lines while adjusting strip travel in a highly precise manner. That technology helped operators of strip processing lines in cold rolling mills or steel service centers to increase the efficiency and flexibility of their operations.

Since then, Umlauf Bridles have been in use all over the world at leading producers of steel or NF metals strip. The Bridles have proven their worth in pickling, hot-dip galvanizing and annealing lines as well as in finishing facilities such as cut-to-length or slitting lines. More than 30 units are in use worldwide. Several new installations are currently underway.

Since 2016, Norbert Umlauf“s sons, Christian and Michael, have taken up active roles in the company, which today is based in Hagen, Germany.

Firmenkontakt
BTU Bridle Technology GmbH & Co. KG
Christian Umlauf
Sedanstraße 41
58089 Hagen / Germany
+49 2331.34008-00
+49 2331.34008-02
christian-umlauf@btu-bridle.de
www.btu-bridle.de

Pressekontakt
VIP-Kommunikation
Regina Reinhardt
Dennewartstraße 25-27
52068 Aachen / Germany
+49.241.89468-24
+49.241.89468-44
reinhardt@vip-kommunikation.de
www.vip-kommunikation.de