CNC plasma cutting process for middle thick plate of aluminum alloy

Date:2016-10-13

Radar electronics, aluminum alloy material has a low density, high strength, good thermal conductivity, corrosion resistance and other excellent properties, widely used in the manufacture of radar antennas, microwave waveguide components, chassis components and heat sinks. At present, the common aluminum alloy sheet having a thickness of 0.5 ~ 100 mm, wherein the sheet (0.5 ~ 8 mm) of material cutting various means, CNC punching, CNC laser cutting, etc. to achieve a lower accuracy and efficiency of materials, under plate (8 ~ 100mm) of material and semi-automatic mode to manual-based, there is a low cutting efficiency, high labor intensity, size, consistency is poor, serious waste material, the subsequent processing of large machines and so on, can not meet the radar electronics field products production needs. CNC cutting technology including CNC flame cutting, CNC high pressure water jet cutting, CNC laser cutting and CNC plasma cutting. CNC flame cutting is mainly used for cutting steel plate, while non-ferrous metals (aluminum, etc.) due to rapid cooling without suitable flame cutting; CNC Waterjet Cutting no material restrictions, but wearing parts (nozzles, etc. ) short life, the subsequent processing costs are high, there is no suitable method of treating waste water; CNC laser cutting is characterized by high precision, high efficiency, but only for an aluminum alloy sheet (less than equal to 8 mm) for fine cutting; CNC plasma cutting technology is not the type of metal material restrictions, cutting thickness of more than 150 mln, the fastest cutting speed of up to 10 m / min, cutting costs is only under the same conditions of laser cutting equipment 1/3. Here for the cutting efficiency and material utilization and low aluminum alloy plate material under the presence, the use of CNC plasma cutting technology, process test method based on analysis of the impact of process parameters on cutting efficiency and utilization for practical applications CNC plasma cutting reasonable choice of parameters to provide guidance.

CNC plasma cutting technology works: high temperature and high plasma arc as heat source, using the optimized design of the nozzle to produce the compressed high temperature plasma stream to melt the cut conductive metal, digital program-driven machine tool motion, with the machine movements, high-speed plasma momentum exclude molten metal forming a narrow slit of a thermal processing methods. The plasma power is different plasma cutting technology is divided into three categories: (1) ordinary plasma cutting. According to the working gas used is divided into an argon plasma cutting, oxygen plasma cutting, cutting current 100 A in the following, cutting thickness is less than equal to 30 mm. (2) constricted plasma cutting. Since the plasma arc is compressed again, the current density, further cutting arc energy concentration, can significantly improve the cutting speed and processing quality. (3) plasma cutting. Its plasma current density of ordinary several times, and arc stability, high precision cutting, laser cutting up to the lower limit. This study will use sophisticated technology test plasma power.

Test conditions: CNC plasma cutting device, used by the US Treasure HPR400XD models fine plasma supply with arc voltage automatic adjusting system, use H35 plasma gas, N: shielding gas, cut square, circular and other simple shape of the aluminum alloy (5A06 grades ) blank plate, sheet thickness 12 Inln and 80 mm, not optimized cutting path and speed. 12 mln and 80 mm thick aluminum plate cutting situation shown in Figure 1, kerf width and sheet thickness are associated, respectively, 1.5 mm and 6.8 lnm. 12 nun thickness of the plate cut quality is very good, the case of 80 mm thick plate cutting analysis, processing parameter is set to: Cutting current 400 A, the cutting speed of 830 mm / min. After measurement, the vertical cross section of less than 30, the straightness of ± 0.2 mm, section roughness Ra25, the lower edge of cut VI substantially no slag. Therefore, the use of CNC plasma cutting technology and set a reasonable cutting parameters to solve the problem of cutting the aluminum alloy plate is feasible. Cutting efficiency is mainly determined by the cutting speed. For thick aluminum plate, need the right cutting speed, too fast, you can not cut through the plate material; speed is too slow, will have a rough cross-section missing, the lower edge of the cut there are more slag. 2, compared to Figure 1, in the cutting current and other parameters remain unchanged, as shown in the cutting speed to 600 mm / min, at the lower edge of the incision very serious slag, increasing the workload of the follow-up. In addition, the need for full compliance cutting speed Ge lJl3], be reasonable acceleration, deceleration, or else, in the outline of the corner easily over-burning, scarring, under the influence of material quality. Thus, according to the sheet thickness required cutting speed set reasonable, and in accordance with the contour speed planning, improve cutting efficiency while ensuring the effect of cutting conditions.

Material utilization is mainly determined by the allowance, kerf width, squareness and straightness section, smearing the outer contour and the inner contour of the arc transition phenomenon (see Figure 3) and so may affect the allowance is provided, wherein the cutting slit width and sheet thickness associated section squareness and straightness can obtain the optimal solution (see Figure 1) through a reasonable set of cutting process parameters. Figure 3 shows plasma cutting is bound to exist two phenomena, the outer contour of smearing is due to the plasma arc cutting irregular shapes, the cutting Plasma Arc is not perpendicular to the plate surface, the upper surface of the first lower surface being cut , was cut into rectangular fillet (from the right in Figure 2 can also be seen); the inner contour of the arc transition phenomenon is due to the plasma arc as a whole was cylindrical in shape, similar to the machining tool, it will inevitably produce fillet. Obviously, the inner contour arc transition phenomenon does not affect the allowance is set, and the outer contour smearing allowance will increase and reduce material utilization; can be common edge by using the side by the bridge after another cutting path planning, etc. the solution to this problem. In addition, since the cutting edge is lower than the thermal deformation extent piercing through a lot, you need to start planning from the cutting edge and end cutting path (see Fig. 1 on the left of the circular path). Therefore, rational planning of the cutting path, reducing the allowance, improve material utilization, saving subsequent machining time.

Conclusion (1) the use of CNC plasma cutting technology to solve the problem of cutting the aluminum alloy plate is feasible, we need to choose reasonable parameters, so that the vertical cross-section, straightness and roughness optimal state. (2) cutting speed need a reasonable set according to the sheet thickness and the speed according to the outline plan, to further improve the cutting efficiency while ensuring the effect of cutting conditions. (3) requires rational planning of the cutting path, further reducing the allowance set, improve material utilization, and save the subsequent machining time.