The Control Measures of Cutting Quality of CNC Flame Cutting Machine

With the need of modern industry, CNC flame cutting machine is more and more widely used in the process of production and machining. It can cut out all kinds of parts with difficult shapes, especially the parts with complex shapes, which can achieve twice the result with half the effort. It is mainly used in the cutting of plate structure, and the cutting quality of structural parts directly affects the welding quality of workpiece and the overall performance of product. The NC flame cutting machine makes use of its advantages of cutting automation and centralized cutting, which greatly improves the utilization ratio of plate in the cutting link, and improves the cutting quality and production efficiency of plate, and also increases the production and efficiency of energy saving for enterprises.

1.Factors and control measures affecting quality of CNC flame cutting

Cutting quality refers to the surface roughness of the cutting section of the workpiece, the degree of melting and collapsing edge on the edge of the cut, the precision of the dimension of the part, the uniformity of the hanging slag and the width of the cut seam at the edge of the cut, etc. The cutting quality and its dimensional accuracy can be improved by using high precision and high performance CNC cutting equipment, but the cutting gas purity, cutting parameters, reasonable CNC cutting program and so on also play a decisive role in the control of CNC cutting quality.

2.Purity of cut gas

The essence of flame cutting is the process of burning the cut material in pure oxygen, so the purity of oxygen is an important factor affecting the quality of CNC flame cutting. If the purity of oxygen is not enough, the cutting surface is rough and the slag is hung at the lower edge of the incision, which not only increases the oxygen consumption, but also increases the cleaning time and the waste of working hours. Using bottled gas with high purity and stable pressure can not only improve cutting quality, but also save energy. Therefore, high quality oxygen and gas is the fundamental guarantee to improve efficiency and obtain high quality cutting surface, and the purity of oxygen should be greater than or equal to 99.5%.

3.Selection of Reasonable Cutting Parameters

According to the size of the plate thickness, the appropriate preheating flame power, cutting nozzle height and model, gas pressure, cutting speed can make the cutting surface smooth, the cutting wave mark small top and bottom edge is square, the cut scale and slag are easy to remove. Preheating flame is an important process parameter that affects the quality of flame cutting. The preheating flame power should be selected according to the thickness of the plate, the type and quality of the cutting nozzle, and the power of the preheated flame should be increased according to the increase of the thickness of the plate. The cutting nozzle type should be selected according to the thickness of the plate. The larger the cutting nozzle number, the thicker the cutting steel plate thickness. The height of the cutting nozzle shall be based on the thickness of the workpiece and the length of the preheated flame To determine. If the height of the cutting nozzle is too low, the cut will collapse, the spatter slag will easily block the cutting nozzle, and the height of the cutting nozzle is too high and the heat loss is large, which will weaken the preheating effect and increase the deformation, resulting in the decrease of cutting speed and quality. The cutting oxygen pressure depends on the cutting nozzle type and the cutting nozzle number. In the actual cutting, the pressure is determined according to the "wind line" test. When the wind line is the clearest and the longest length, the appropriate pressure value is reached. If the cutting oxygen pressure is too high, it will not only cause waste of resources, but also produce regular grooves near the surface of the cutting parts, which will bring difficulties to the subsequent slag cleaning. The cutting oxygen pressure is too low and the cutting surface has thicker scale melting Enter, more difficult to get rid of. If the gas pressure is too high, it will cause overheating, and a large groove will be formed on the cutting surface near the top; if the gas pressure is too low, it is difficult to ensure the smooth progress of the cutting.

The cutting speed is related to steel plate material, thickness, cutting nozzle form, gas type and purity, and generally slows down with the increase of workpiece thickness.Too fast and too slow cutting speed can not guarantee the quality of the cut, too fast cutting speed will appear cutting penetration, not cut off phenomenon, resulting in CNC flame cutting interruption; too slow cutting speed will make the upper edge of the cut melt, need to cut again, not only cause waste of resources, reduce productivity, but also affect the surface quality of the cut. 

Choosing the appropriate cutting speed can make the slag of cutting surface very little, even no slag, easy to polish.The cutting speed can be determined by sound, observation of the quality of the cut marks below and below the slag spark Whether the break is appropriate. When the slag flows at the appropriate cutting speed, it will make a regular "bang" sound, and the slag spark mountain pass will be straight line or slightly forward with the cutting nozzle.