Oxy-flux cutting

Non-ferrous metals and their alloys, cast iron, stainless steel, chrome and chrome-nickel steel can not cut conventional oxy-fuel cutting. To do this, use a plasma arc, and better oxygen flux cutting. The essence of the latter is that the cutting area by using special equipment is continuously fed flux powder together with the cutting oxygen. Flux burns and melts formed refractory oxides. In addition, flux translates into flowable oxide slag, follow easily from the location of the cut. This cutting is mainly used for working with cast iron and high-alloy steel with thickness up to 70 mm.
As the flux is applied fine-grain iron powder grade PZH5M (GOST 9849 - 74) with a particle size of from 0.07 to 0.16 mm (used for cutting iron and copper). For cutting stainless steel powder is added to said 10-12% aluminum powder brand AR. You can also use aluminum magnesium powder (60-80%) mixed with ferrosilicon (20 - 40%). When cutting chromium and chromium-nickel steel is used PZH5M iron powder with the addition of 25-50% of the scale. When cutting cast iron can be added to this powder 30-35% ferrophosphorus domain. A mixture of iron powder and aluminum powder (15-20%) and ferrophosphorus (10 - 15%) is used for cutting copper and its alloys.
This is cutting-5 URHS installation consisting of torch and flyusopitatelya. Installation can cut manually or by machine and high-alloy chromium-nickel chromium steel with a thickness of 10-200 mm, cutting speed 230-760 mm / min. 1 m section of oxygen consumption is 0,20-2,75 m, acetylene - 0,017-0,130 m and flux - 0,20-1,3 kg. Iron 50 mm cut at speeds of 70-100 mm / min at a flow rate of 1 m of the section 2-4 m of oxygen, acetylene 0,16-0,25 m and 3.5 - 6 kg of flux. When cutting copper alloys are about the same parameters.
Keep in mind that the power of the flame HEATING need to increase by 15-25% compared with conventional gas cutting, as some of the heat of the flame will go to the heat flux. The flame should be normal or slight excess of acetylene. From the end of the mouthpiece torch to the metal surface should be a distance of 15-25 mm. At a small distance can clap and flashback by bouncing particles flux from the surface and getting into the nozzle of the torch. Furthermore, it may be overheating mouthpiece and therefore a violation of the cutting process. The angle of the tool should be done in 1-10 ° in the opposite direction of cutting. To facilitate the process of cutting copper alloys must first be heated to 200-50 ° C, and chromium and chromium-nickel steel - up to 300-400 ° C.
In practice, often made of concrete and reinforced concrete cutting. It is performed by two methods: oxygen lances and spears powder-cutting.
Oxy-cutting lances very well burns holes in the concrete. It allows you to get a hole depth of up to 4 m in diameter and 1.2 m of that sharp can successfully burn holes in steel billet.
With this method, a steel pipe (spear), one end of which is heated to the temperature of melting and attached to the surface of the concrete. After blown oxygen lance, which interacts with a hot butt tube restored. This produces flowable iron oxides, which react with concrete and turn into slag, which are then easily blown. Advancing the tube forward, you can burn a hole in the concrete required.
As you can use a gas lance thin wall tube diameter of 10-20 mm, filled with steel bars for 60-65% of its volume, or wrapped with steel wire outside diameter of 3-4 mm and a thick-walled seamless tube diameter of 20-35 mm. Wire and rods, carried out at a cut the same function as the flux in the flux of oxygen-cutting. Spear is heated, usually carbon electrode or burner.
Power-cut spears characterized in that it uses an iron-aluminum powder in the ratio of 85: 25. As flux, the powder is blown into a jet of oxygen in the cutting area. The parameters of the work, this might include the following. For example, when burning a hole diameter of 50 mm and a depth of 500 mm, the rate of progress will be 120-160 mm / min at a pressure of 0.7 MPa oxygen, powder 30 kg / h and the flow rate of the spear (tube) 4 mm per meter of length holes.
Holes with a depth of 1.5 m diameter and the same rate of decline deepening to 40-70 mm / min at an oxygen pressure of 1.0-1.2 MPa, the flow flux of 30 kg / h and the flow rate of 6 mm spear on 1 m of the hole.
Gouging - a kind of flame cutting. It is designed to cut on the metal surface of the relief in the form of one or several, separate or combined grooves. Welding, cutting, this is often used to cut out the defective parts of joints. When this source of heating metal cutting will be a torch and flame and molten slag, which during its spreading stirs deep-metal layers.
For this type of work are good cutters type RPA and the PKK. Cutting mode and the angle of the tool plays an important role in the effectiveness of gouging.
At the initial stage it is necessary to warm up the incision to the ignition temperature. The cutter should be placed at the same angle of 70-80 ° to the surface of the metal. Before serving, cutting oxygen instrument should be given tilt angle of 15-45 °. In the cutting process occurs patchy burning metal, thereby providing effective cleaning metal surfaces, including by promoting a uniform tool for the intended line of cut.
Position in this type of cutter cutting detail shown in Figure 134.

Схема поверхностной кислородной резки

Fig. 134. Scheme of surface oxygen cutting: 1 - Mouthpiece 2 - slag, 3 - groove.

The width and depth of the groove decreases with increasing cutting speed. In addition, the depth of the groove is smaller when the angle decreases mouthpiece instrument and when the pressure cutting oxygen. Slot width depends on the diameter of the jet of oxygen. During gouging to make the width of the groove is 5-6 times greater than its depth, to prevent the occurrence of sunsets on the surface.
If you need to clean up the numerous defects in a large area, in this case, to make cuts "herringbone" in one or more passes using oscillatory motion cutter.
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