Manufacturing methods of steel fibers

There are four main manufacturing methods for steel fibers used in steel fiber concrete. The following are detailed information:
1. Wire cutting method
This processing method is relatively simple. Generally, cold-drawn steel wire with a small diameter of 0.4-0.8mm is used as raw material, and the steel wire is cut into short fibers according to the specified length. The tensile strength of steel fibers produced by this method is much higher than that of steel fibers processed by other methods, and can reach 1000-2000MPa.
The processing means can be cutters and punches. In order to improve efficiency, rotary tools are often used for cutting. Since cold-drawn steel wire is expensive, the cost of steel fibers produced by this method is relatively high. Another disadvantage of this method of producing steel fibers is that the surface is relatively smooth and the bonding strength with substrates such as concrete is relatively low. In order to increase the bonding strength between steel fibers and substrates such as concrete, it is often solved by changing the shape of steel fibers, that is, by producing special-shaped steel fibers. There are three common methods:
⑴ Edge pressing method: Before cutting the steel wire, use the feeding roller of the feed wire to press out prismatic pits on the steel wire.
⑵ Waveform method: Before cutting the steel wire, use the feeding roller of the steel wire to press the steel wire into a waveform before cutting it.
⑶ Hook method: Before cutting the steel wire, use the feeding roller of the steel wire to press out the hook shape at equal distances before cutting it.
The steel fiber shown in Figure 1e is called "DRAM Ⅸ" in foreign countries. During production, water-soluble adhesives are often used to bundle and bond them together, thereby reducing the aspect ratio (Figure 1h). After this bundled steel fiber is put into the concrete mixer, the adhesive quickly dissolves in water, and the steel fiber is evenly distributed in the concrete.
2.Manufacturing methods of steel fibers
The thin plate shearing method is a method of cutting cold-rolled thin steel plates into steel fibers. Before shearing, a special small longitudinal shearing machine is used to cut the thin cold-rolled coil into a strip steel coil. The width of the strip steel coil is the same as the length of the steel fiber. Then the strip steel coil is continuously fed into a rotating tool or a common punching machine for cutting. The axis of the rotating tool is perpendicular to the feeding direction of the thin plate. The raw material is generally an annealed cold-rolled steel plate, and an unannealed cold-rolled steel plate can also be used to improve strength.
3. Ingot milling method
The raw material used is a thick steel plate or an ingot. When the steel fiber is cut by a rotating flat-blade iron knife, the steel fiber will produce a lot of plastic deformation and twist between the axes, which can increase the bonding force with the matrix, such as concrete. If ordinary low-carbon steel is used as the raw material, the curvature of the cut steel fiber is about two and a half times that of the parent material after hardening, becoming a high-strength and high-hardness steel fiber.
4. Melting steel wire drawing method
The scrap steel is melted into 1500-1600℃ molten steel in an electric furnace, and then a high-speed rotating melting wheel is approached to the molten steel on the surface of the molten steel. Many grooves are engraved on the melting wheel according to the requirements of the required steel fiber. When the melting wheel descends to the liquid surface, the molten steel is scraped out by the groove and thrown out by the centrifugal force of the high-speed rotating melting wheel, and is cooled and formed at a speed of 10,000°C/second. Water must be passed through the melting wheel to maintain the cooling speed. The melting method for producing steel fiber is currently the most promising method for producing steel fiber in the world. Its raw materials come from a wide range of sources, and all kinds of scrap steel can be used. Due to the low cost of raw materials, simple manufacturing process, and high production efficiency, this type of steel fiber is the cheapest. Since the melting method uses an electric furnace to melt molten steel, it is relatively easy to adjust the chemical composition of the molten steel, thereby producing steel fibers and other metal fibers of various materials. By changing the size of the grooves on the melting wheel, the rotation speed of the melting wheel, and the immersion depth, the geometric dimensions of the steel fiber can be changed. This method eliminates the complicated processes of the above three methods from steelmaking to steel rolling, wire drawing (or plate rolling), so that the molten steel is formed once and processed into the final product, and its economic effect is very significant. Strong plastic and asbestos friction materials.