Method of producing metal beams with a top-hat profile

Abstract

A method for producing metal beams having a top-hat profile comprises the hot rolling of slabs (13), ingots (12), billets, preliminary profiles (14) or similar semifinished products in a rolling train. The rolling train comprises at least two roll stands. Using at least two shaping passes during a single rolling process in a number of rolling stations at hot-rolling temperature, preferably simple irregular pass design turns an entering cross section (10) of a one-part semifinished product into an exiting cross section having a top-hat profile (A), which corresponds geometrically more or less to the profile of the finished product.

Description

TECHNICAL FIELD

The disclosure relates to a method of producing metal beams having a top-hat profile by hot rolling a metal primary material.

BACKGROUND

A method of producing metal beams having a top-hat profile is generally known, for example from CN 102431568 A. This method relates to the production of a center longitudinal beam by hot rolling a three-part arrangement of different semifinished products. The top-hat profile is assembled from two U-shaped profiles and an upper cover plate to form a downward-opening U-shape, wherein the individual parts are produced by hot rolling.

Producing center longitudinal beams from two hot-rolled Z-profiles welded together to form a top-hat profile is also known. This is followed by the usual finishing steps such as straightening, annealing, etc. This method is relatively complex in terms of the work steps required. Welding the Z-profiles results in a microstructural change in the heat-affected zone of the Z-profile. This results in inhomogeneity in the microstructure and material composition. Different material compositions in the region of the weld seam can lead to corrosion. In addition, testing of the finished weld seam, for example by means of ultrasound, is required. In addition, a weld seam also has geometric disadvantages. For example, a notch effect is created by the weld seam. In addition, the material may warp during welding. The weld seam causes stability problems at the beginning and end of the seam. By joining several parts, the errors are added up, such that higher error tolerances ultimately result. Finally, material differences of different Z-profiles from different batches are also problematic.

WO 2007/008152 A1 describes a method for cold rolling a top-hat profile in a single work operation in a rolling device provided for this purpose. The rolling device for producing the desired profile is known from EP1 339 508 B1. With the method, the top-hat profile is rolled or edged, as the case may be, from a flat sheet as primary material. This method is only suitable for processing relatively thin sheets as primary material.

SUMMARY

The invention is based on the object of providing a simplified method for the production of top-hat profiles that avoids the disadvantages described above.

The object is achieved by a method as claimed.

A method is proposed for producing metal beams having a top-hat profile by hot rolling a one-piece semifinished product. In particular, a method for the production of metal beams having a top-hat profile, comprises hot rolling of slabs, ingots, billets or similar semifinished products in a rolling train. The rolling train comprises at least two roll stands. Using at least two shaping passes during a single rolling process in a number of rolling stations at hot-rolling temperature, preferably with simple irregular roll pass design, turns an entering cross section of a one-part semifinished product into an exiting cross section having a top-hat profile, which substantially corresponds geometrically to the profile of the finished product. Within the meaning of the present disclosure, “substantially” means that the exiting cross section of the hot-rolled section corresponds to the geometry and dimensions of the finished product except for minor angular deviations of the individual legs of the profile.

The method is carried out without any further intermediate steps by hot rolling relatively thick semifinished products as primary materials up to the substantially finished product in a hot-rolling train. Thereby, forming a one-piece semifinished product uses at least two shaping passes during a single rolling process in a plurality of rolling stations at hot-rolling temperature. The exiting cross section of the top-hat profile is preferably generated with simple irregular pass design by shaping rolls or shaping passes/precise shaping rolls, as the case may be. Precise shaping is understood to mean profile rolling for producing a profile of a defined finished cross section from a defined initial cross section with a defined number of rolling passes, wherein a simple irregular pass design is understood to mean a precise shaping with which the distribution of the height change over the profile width has at least one plane of symmetry.

Hot-rolling temperature refers to a temperature of the rolled material that is above the recrystallization temperature of the material. In the case of steel as the primary material, this is a temperature well above 900° C. Forming at hot-rolling temperature also means that the rolled material or the semifinished products, as the case may be, are only at hot-rolling temperature or have been heated to hot-rolling temperature before the first pass or before the first forming pass. The other forming passes can be carried out at a correspondingly lower rolling temperature.

Optionally, the rolled material can be heated before and/or after the individual rolling steps or passes, as the case may be, for example by using heating devices in the form of induction furnaces or the like.

Preferably, the temperature when carrying out the first forming pass or at the first roll stand, as the case may be, is between 950° C. and 1300° C.

Examples of semifinished products are slabs with a rectangular cross section and dimensions of 500 mm to 1200 mm×150 mm to 450 mm, so-called “blooms” with dimensions of 400 mm to 700 mm×150 mm to 450 mm or so-called “beam blanks” (pre-profiles). The latter can, for example, have a width of 400 mm to 750 mm and a height of 400 mm to 500 mm.

It is advantageous if the entering cross section of the semifinished product has a rectangular cross section whose material distribution corresponds approximately to the material distribution to be produced with a first pass of the rolling process.

The hot rolling process can be carried out with a wide variety of stand configurations and rolling methods. In the case of rolling in pure duo mode (using duo roll stands), for example, provision can be made to form the entering cross section of the semifinished product to the exiting cross section using seven to thirteen shaping passes.

According to a variant of the method, the rolling process is carried out with an open arrangement of at least two, preferably from three to eight, roll stands arranged side by side. Such an open rolling train is described, for example, in DE 39 02 889 C2.

Alternatively, the rolling process is carried out using four to eight roll stands arranged one behind the other.

Thereby, the rolling operation can be carried out using roughing roll stands and finishing stands in tandem arrangement, in a manner that is at least partially reversing. A tandem arrangement is generally understood to mean several roll stands moved together, through which the rolled material passes one or more times. With this configuration, the finishing roll stands can be operated in reversing mode.

Alternatively, the rolling process can be carried out using four to ten roll stands arranged one behind the other, comprising roughing roll stands, finishing roll stands in tandem arrangement operated in reversing mode, and finishing roll stands operated in continuous mode.

In another variant of the method, the rolling process can be carried out using seven to eighteen roll stands using roughing roll stands and/or roll stands in tandem arrangement, which are operated in reversing mode, and finishing roll stands, which are operated continuously.

Finally, the rolling process can be carried out completely continuously using seven to twenty roll stands arranged one behind the other, for example in a continuous rolling train.

In principle, the rolling process can be carried out using duo roll stands and/or universal roll stands. A universal roll stand is understood to mean a roll stand with four rolls per stand, wherein two of the rolls are arranged horizontally and two rolls are arranged vertically.

Preferably, a geometric measurement of the rolled material is carried out prior to and/or after each rolling station or forming pass, as the case may be. Such a measurement can be performed by laser and can interact with a hydraulic adjustment of the rolls of the individual roll stands.

After the last rolling pass or forming pass, as the case may be, a cooling treatment of the top-hat profile produced or the rolled material, as the case may be, for microstructure adjustment can be provided, preferably using a simulation model and/or a microstructure detector. Microstructure detection can be performed by means of laser or ultrasound.

With a preferred variant of the method, it is provided that, after the last forming pass of the rolling operation, the inclination of the flanges of the top-hat profile is between 0.1 and 15 degrees relative to a perpendicular to the axis of symmetry of the top-hat profile.

It is expedient that the rolling process is followed by a bending process, preferably with a straightening machine or a bending device. The bending process transforms the profile into its final shape, in which the legs and crossbars of the top-hat profile are substantially perpendicular to each other.

The bending operation can be carried out by means of a bending device after the last roll stand of the hot-rolling train or with an additional universal roll stand.

The rolling process can be operated in “batch or semi-endless mode (hot charging).”

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained below with reference to a forming process illustrated in the drawing. The drawing shows alternative semifinished products and profiles after successive forming passes.

DETAILED DESCRIPTION

The entering cross section of the semifinished product to be hot-rolled is designated by reference numeral 10. This entry cross section 10 is rectangular and has a material distribution that roughly corresponds to the material distribution of the first forming pass. The semifinished product to be formed is, for example, a block 11 (bloom) with rectangular dimensions between 400 mm and 700 mm×150 to 450 mm, which is formed into the top-hat profile designated with reference character A using ten successive forming passes. The successive forming passes of the calibration for producing the top-hat profile are designated with reference numerals 1 to 10. Reference characters H to A thereby designate the successively generated profiles. For this purpose, in the exemplary embodiment described, ten shaping passes are required, which passes can be carried out, for example, in ten duo roll stands arranged one behind the other. As can be readily seen from the finished top-hat profile A after the forming pass 10, it still exhibits slight angular deviations from a strictly rectangular geometry. The finished top-hat profile A is, for example, the top-hat profile of a center longitudinal beam. The angular deviations after the last forming pass 10 are eliminated by a bending operation, for example by means of a straightening machine or by means of an additional universal roll stand after the last forming pass. In the illustrated exemplary embodiment, the inclination of the flanges 12 of the top-hat profile A relative to a horizontal line is approximately between 0.1 and 15 degrees.

Alternatively, the primary material for the forming process or the semifinished product to be formed, as the case may be, can be the slab 13 also shown in the drawing with rectangular dimensions between 500 mm and 1200 mm×150 mm to 450 mm or the preliminary profile 14 with dimensions between 400 mm and 750 mm×400 mm to 500 mm.

LIST OF REFERENCE SIGNS

1-10 Forming passes

H to A Profiles

11 Entering cross section

12 Block (bloom)

13 Slab

14 Preliminary profile (beam blank)

Claims

1.-13. (canceled)

14. A method for producing metal beams having a top-hat profile (A), comprising:

hot rolling semifinished products in a rolling train with at least two roll stands,

wherein an exiting cross section having a top-hat profile is formed from an entering cross section of a one-part semifinished product using at least two shaping passes during a single rolling process in a plurality of rolling stations at hot-rolling temperature, and

wherein the exiting cross section substantially corresponds geometrically to a profile of a finished product.

15. The method as in claim 14,

wherein the semifinished products are slabs (13), ingots (12), billets, or preliminary profiles (14).

16. The method as in claim 14,

wherein the at least two shaping passes have a simple irregular pass design.

17. The method according to claim 14,

wherein the entering cross section of the one-part semifinished product has a rectangular cross section whose material distribution corresponds approximately to a material distribution to be produced with a first pass of the hot rolling.

18. The method according to claim 14,

wherein the entering cross section of the one-part semifinished product is formed into the exiting cross section using seven to thirteen shaping passes.

19. The method according to claim 18,

wherein the hot rolling is at least partly carried out with duo roll stands.

20. The method according to claim 14,

wherein the hot rolling is carried out with an open arrangement of three to eight roll stands arranged side by side.

21. The method according to claim 20,

wherein the hot rolling is carried out using four to eight roll stands arranged one behind the other.

22. The method according to claim 21,

wherein the hot rolling is carried out using roughing roll stands and finishing roll stands in tandem arrangement, in a manner that is at least partially reversing.

23. The method according to claim 14,

wherein the hot rolling is carried out using four to ten roll stands arranged one behind the other, comprising roughing roll stands, finishing roll stands in tandem arrangement operated in reversing mode, and finishing roll stands operated in continuous mode.

24. The method according to claim 14,

wherein the hot rolling is carried out using seven to eighteen roll stands using roughing roll stands and/or roll stands in tandem arrangement, which are operated in reversing mode, and finishing roll stands, which are operated continuously.

25. The method according to claim 14,

wherein the hot rolling is carried out completely continuously using seven to twenty roll stands arranged one behind the other.

26. The method according to claim 14,

wherein the hot rolling is carried out using duo roll stands and/or universal roll stands.

27. The method according to claim 14,

wherein, after a last forming pass (10) of the hot rolling, an inclination of flanges of the top-hat profile (A) is between 0.1 and 15 degrees relative to a perpendicular to an axis of symmetry of the top-hat profile.

28. The method according to claim 14,

wherein the hot rolling is followed by a bending process with a straightening machine or a bending device.