DD262055A1 - METHOD FOR PRODUCING STEEL FIBERS - Google Patents

Abstract

The invention relates to a method for producing steel fibers from structural steel by milling from slabs, sinkers or billets for use as an aggregate in producing a building material mixture for different applications, wherein the steel fiber meets the strength requirements of the respective applications and allows the effective production of steel fiber concrete.

Description

For large-scale trials with steel fiber reinforced concrete, larger quantities are produced with roll milling cutters or with disk cutters coupled as set milling machines. The required fiber length is realized by the cutter width. When using milling cutters, a groove can be ground to determine the chip width in the tool. To ensure the fiber quality and thus also its strength values as the most important criterion, it is generally necessary to use simultaneous milling

 On conventional horizontal or universal milling machines, steel fibers with the following values were produced as an example:

η t S b d Increase the tensile strenght U min " ¹ mm mm min " ¹ mm mm on% 28 0.8 500 2.0 0.65 155 32 1.6 160 2.0 0.6 178 35 1.6 160 2.7 0.8 166 35.5 1.6 180 2.3 0.5 165 35.5 0.8 500 1.9 1.9 125 45 0.8 500 1.9 1.9 135 45 1.8 200 2.06 0.67 136 71 2.0 160 2.45 0.48 167 71 3.0 200 2.16 0.85 213

The milling of the material transverse to the rolling direction is realized by turning the steel slab, e.g. B. 925 χ 240 χ 1500mm, be separated in lengths of 375 mm, so that the lying on the Frastisch material has a length of 925 mm, a width of 375mm and a thickness of 240mm.

Claims (1)

- 1 - ZbZ UOiJ Claim: A method for producing steel fibers for use in building material mixtures, in particular in concrete and mortar mixtures, characterized in that a low-carbon structural steel used in the state of Stahlvorbrammen, -platinen or billets and perpendicular to its rolling direction by milling mitteis roll or side milling cutters whose Slope angle is in the range of 15-40 °, is machined in the asynchronous milling and the dimensions of the chip in its length I = 1.5-2.5 times the largest grain of the mineral aggregate, a fiber thickness d = 0.4-0.7 mm and the fiber width b: fiber thickness d is in the ratio of 3 to 7. Field of application of the invention The invention relates to a method for producing steel fibers from structural steel by milling from pre-slabs, sinkers or billet material for use as an aggregate in the manufacture of a building material mixture for different applications. Characteristic of the known technical solution There are known building materials that consist of bituminous mix, cement concrete or other starting materials and which are mixed to achieve certain properties of steel fibers (DT-AS 2723382, DD-WP 208385). The use of steel fiber reinforced concrete in mining, engineering, civil engineering, road and aerodrome construction and special structures made of reinforced concrete usually cut steel wire fibers are used, however, when they are fed into the mixing process require special separation and thus significantly reduce the performance of the mixing plants. Furthermore, known are cut from sheet metal or punched fibers and those obtained by extraction from a molten steel (DT-OS 2827731). Since material with definable and testable properties is necessary for use as a building material of civil engineering, the extraction fiber is in most cases not applicable. However, the other fibers are relatively expensive due to the use of highly finished or multi-machined stock or alloyed or low carbon steels. Object of the invention The aim of the invention is, when using a low-cost starting material, as z. B. is a commercially available structural steel to produce a steel fiber that meets the strength requirements of the various applications and allows the effective production of steel fiber construction materials. Explanation of the essence of the invention The invention has for its object to produce for the production of steel fiber casts, in particular for steel fiber reinforced concrete and mortar, spun steel fibers, both secure the desired strength values when using commercially available structural steel material and are technologically easy to process for mass concrete. According to the invention the object is achieved in that a non-mechanical or thermal forming processes exposed, low-carbon structural steel in the form of pre-slabs is machined by machining with helical roller or disc cutters with synchronous milling. Assuming that the resulting steel fiber must meet certain parameters, in contrast to other applications of the tools used here, a rake angle of 8 ° -20 ° is required because low rake angle cause a higher compression of the chip. This can have a negative effect on the span in the form of structural cracks and a resulting loss of strength. In connection with this rake angle, and thus the emergence of a shear chip, the pitch angle λ of the cutter cutting edges 15 <λ <40 °, since at λ> 40 ° too much sickling of the fiber or at λ <15 ° too much machine load arises , Based on the use of a variety of tools and workpiece material, a sample cut is to determine the best cutting parameters and the rake angle in the specified range perform to influence the chip flow according to the requirements of the fibers. The chips must, for technological and strength reasons, have the dimensions L = 1.5 to 2.5 times the maximum aggregate of mineral aggregate, in their maximum thickness d = 0.4 to 0.7 mm and a ratio of their width b to the fiber thickness d from 3 to 7. embodiment The advantages of a shaved steel fiber from a commercial structural steel arise on the one hand from the low price of the semi-finished material and on the other hand by their uncomplicated, without special aids possible use in all technological mixing and installation processes for concrete and mortar by the favorable cross-sectional and surface ratio and thus possible low fiber length compared to steel wire fibers.