JPH04272135A - Method and device for rolling wire and barstock - Google Patents

Abstract

The invention relates to a method and an arrangement for the rolling of wires and rods with a reduction in cross-section of at least 50%. According to the invention the cross-sectional area of the rolling stock is reduced and its properties modified in a first step involving a preliminary deformation, whereupon the rolling stock is heated and further deformed in a second step.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for rolling wire or bar stock from metallic material, in which a cross-section reduction of at least 50% is effected on the rolled material.

0002

BACKGROUND OF THE INVENTION Rolling or drawing methods are always used to produce wire and bar materials, in which case materials with large cross-sections or large diameters, in particular more than 10 mm, are heated at high temperatures, preferably above 1000°C. Materials which are deformed by rolling and have a small diameter, in particular less than 5 mm, are deformed at room temperature, usually in several stages, by drawing and possibly with softening annealing between these drawing stages.

In the known method of the above-mentioned type (CH 654 496), continuous isothermal rolling is used in rolling mill rows with heated rolls, optionally followed by A wire with a small cross section is produced by subsequent drawing without intermediate annealing. In this case, the preheating and rolling temperatures are chosen high in order to avoid work hardening of the material or to save intermediate annealing operations. In this case, oxidation of the surface, coarse structure and hardening of the more carbon-containing alloy during rapid cooling from the heat of rolling are disadvantageous.

In another method of hot rolling high strength steel (GB 2194186), the rolled material is rolled in at least two stages, the last stage being:
The rolling process is carried out with a deformation of at least 50% in at least two rolling stages at a temperature close to, but above, the AC3 temperature of the alloy. In this case, structural inhomogeneities over the cross-section of the workpiece due to oxidation of the material during heating and increased rolling wear and the formation of surface martensite during intercooling are disadvantageous.

[0005] In another rolling method for manufacturing strip steel (German Patent Application No. 2725155),
The wire is heated without decarburization in a neutral atmosphere to a temperature above the AC3 temperature of the alloy and rolled at this temperature, after which
It has been proposed to cool the rolled material and hold it isothermally above the martensitic point until a bainitic structure is obtained. In this method, intended for producing reinforcing elements in pneumatic vehicle tires, heat-treated structures, which are not intended for further processing by thermal processes, and austenite grain sizes, which are not sufficiently reduced by transformation processes, are disadvantageous.

From FR 2 579 116 a method is known for the continuous production of metal profiles, in which a wire or bar material is removed from a storage device and straightened in a roll straightening machine. After that,
The rolled material is first preheated by conduction, then final heated by induction and deformed in several rolling stages. This method is expensive. This is because surface cleaning of the rolled material, for example with a brush, is necessary before conductive heating. Furthermore, in this case, due to the surface irregularities and the point-like current supply to the material, heating points or regions are formed in the material that can be heated to high temperatures for a short time and thereby harden. Better heating conditions must be obtained by means of expensive induction final heating. The straightening process produces plastically deformed or work-hardened areas in the material, especially in areas close to the surface of the material, which result in heterogeneity in the material's structure during rolling below the material's transformation temperature. give rise to sexuality.

For hot drawing hardenable steels, Austrian Patent No. 227,643 proposes a method in which the drawing material is heated by conduction to a temperature below A1. This method is only suitable for surface-treated or textured materials, in which case the texture depends on the drawing process and, in particular, on the texture of the material.

[0008]

OBJECT OF THE INVENTION The problem on which the invention is based is to produce fine-grained materials with high surface quality and homogeneous formation over the cross-section of a material with advantageous application properties and good processability. In addition to the method mentioned at the beginning, which can easily produce rolled products with a small cross-section and a microstructure, this method is particularly useful for producing rolled products with a simple structure, excellent accuracy, high precision, and special properties. Our objective is to provide a rolling equipment that guarantees

[0009] This problem arises in the methods mentioned at the beginning, in which the cross-section of the rolled material is reduced and the material properties are changed by pre-deformation in the first step, and then in the second step the rolled material is made deformable. Advantageous configurations and expansions are described in claims 1 to 8, in which the rolled material is heated to an improving temperature and further deformed or rolled. Further advantageous developments of the invention are obtained by arranging the preforming device before the heating device and the rolling device for introducing energy into the rolling device.

[0010] The method according to the invention provides that the blank or rolled material is predeformed in a first step before heating to a temperature that improves its deformability and subsequent rolling, the material properties of this material being changed. Excellent at that. The reduction of the cross-section of the rolled material during pre-deformation and the work-hardening of the material and the adjustment of the internal stress state, preferably at approximately room temperature, create new dislocations in the crystal lattice, displacing and blocking these dislocation sites and increasing the lattice structure. It was found that it causes stress. Surprisingly, it has furthermore been found that by heating the rolled material in hardenable steel, as planned in the second stage of the process according to the invention, preferably to a temperature barely below the transformation temperature or to the AC1 temperature, the lattice stress can be reduced. is destabilized and during the subsequent rolling deformation, a particular grain refinement is already achieved with a smaller degree of deformation, and this grain refinement is intensified in a further rolling step. If deep predeformation by rolling with a cross-section reduction of at least 1.8% is carried out, a particularly homogeneous, finely structured structure with advantageous use properties results in the rolled product. It has also been found that predeformation significantly improves the current transfer conditions in the contact area of the conduction heating device, so that surface and structural defects due to arc formation or local material overheating do not occur. The constant cross-section of the rolled material, which can be achieved by pre-deformation, additionally allows easier and more precise temperature control during conduction heating. Situations using heated or descaled materials can use the method according to the invention particularly advantageously, thereby making it possible to produce rolled products with special internal and surface qualities.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention also relates to an apparatus for carrying out the method, which apparatus will be explained in more detail with reference to the drawings.

In the apparatus shown in FIG.
After descaling, pickling, grinding, etc., the material is removed from the supply device 1, for example a cylinder 11 or a laminated container (not shown), and sent to the preforming device 2. A preforming device of this type can consist of two cold rolling stands 21, 22 in series, in which the cross section of the blank is reduced and a precise circular or flat cross section is rolled.

[0013] For the predeformation, drawing devices or the like can also be used, but in this case the process is made more difficult to start or more complex to carry out.

After the rolled material leaves the preforming device, it has a substantially straight condition, a smooth surface with a constant or unchanged cross-section, and crystal lattice stresses in the material. Contact rolls 31, 32 in the heating device 3
The current circuit is closed by , current is passed from the power supply to the rolled material and resistive heating is achieved. A temperature measuring device 30 connected after the heating zone makes it possible to regulate the energy supply, etc. or to control the process. A temperature compensation device 4 can also be arranged before the deformation device 5. The deforming device 5 preferably has at least two rolling stands 5.
Preferably it consists of a cassette rolling mill for a minimum deformation of 1,52 or 50% in total.

The finished product is removed from the storage device 6, for example a cylinder 61 or a stacked container. The contact rolls of the pre-forming device 2 and the rolling device 5 and possibly the heating device 3 are such that the speed at which the rolled material exits after pre-forming, the speed at which it passes through the heating device and the speed at which it enters the rolling device are approximately the same magnitude. Particularly good results are obtained with the device according to the invention if tensile stresses are controlled to occur in the rolled material between and within the rolling material. For such control, it has become clear that global adjustment using temperature is advantageous.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of an apparatus according to the present invention.

[Explanation of symbols]

2. Front deformation device 3 Heating device 5 Rolling equipment

Claims (1)

[Scope of Claims] [Claim 1] A method for rolling a wire or bar material from a metal material, in which the cross-section of the rolled material is reduced by at least 50%, in which the cross-section of the rolled material is reduced by pre-deformation in a first step. A method for rolling wire or bar material, characterized in that the material properties are reduced and the material properties are changed, and then in a second stage the rolled material is heated to a temperature that improves its deformability and further deformed or rolled. . 2. The rolled material is pre-deformed and work-hardened by cold deformation in a first step, and the internal stress state of the material is adjusted, resulting in a cross-sectional reduction of at least 1.8%. The method described in Section 1. 3. One of claims 1 and 2, characterized in that the predeformation and work hardening scheduled in the first stage and the adjustment of the internal stress state of the material are carried out by cold rolling.
The method described in. 4. The rolled material, which has been predeformed and cold work hardened in a first stage and has an internal stress state of the material, is heated in a second stage by a rapid heating method to a temperature that improves the deformability and at least Claims 1 to 3 characterized in that it is further deformed in the rolling direction in two successive rolling stages.
The method described in one of them. 6. The metal material to be transformed is heated in a second stage by a rapid heating method to a rolling temperature of the maximum AC temperature or transformation temperature so as to form a γ structure, and is deformed in the rolling direction in at least two rolling stages, Claims 1 to 5 characterized in that an increase in the temperature of the rolled material during further deformation is prevented, if appropriate by cooling or by the use of a coolant.
The method described in one of them. 7. One of claims 1 to 6, characterized in that the first step is immediately followed by a second step or that these method steps are carried out immediately one after another in a row. The method described in. 8. The pre-deformation of the first stage or the further deformation of the second stage is carried out or controlled in such a way that a tensile stress is applied to the intermediate rolled material. The method described in one of 7. 9. A pre-deformation device (2) is arranged in front of the heating device (3) for introducing energy into the rolled material by direct energization and the rolling device (5). equipment for rolling wire or bar material from metallic material, in which a reduction of the cross section by % is carried out 10. Device according to claim 9, characterized in that the preforming device is formed by a cold rolling mill. 11. Device according to claim 9, characterized in that the rolling device (5) is constructed for at least two stages of deformation. [Claim 12] Pre-deforming device (2) or rolling device (5)
) and optionally the heating device (3) have adjustable drives, which drives are connected to a control device and can be adjusted together. 12. The device according to one of items 9 to 11. 13. At least one device before the heating device (3)
one rolling material temperature measuring device (30) is connected, which temperature measuring device optionally controls the energy supply or drive to the heating device (3); Device according to one of claims 9 to 12. Claim 14: Pre-deformation device (2) and heating device (3)
) and, if appropriate, a temperature compensation zone (4) and a rolling device (5) are arranged one behind the other in the rolling direction, so that the rolled material (
14. Device according to claim 9, characterized in that 7) can be passed through or processed substantially in a straight line. 15. Device according to claim 9, characterized in that it deforms hardenable steel.