According to the different mixing ratio of gas and oxygen, cutting flame can be divided into carbonization flame, neutral flame and oxidation flame.
When acetylene is used, when the volume ratio of oxygen to acetylene is1.1~1.15, the flame is neutral and consists of flame center, inner flame and outer flame. The center of the flame is a mixture of acetylene and oxygen.
The internal flame is the reaction zone where acetylene and oxygen are burned once, and its reaction formula is C2H2 +O2→2CO+ H2. The maximum temperature is about 3100 c at a distance of 2~3mm from the flame center. The outer flame is the area where CO and H2 produced by primary combustion are oxidized and synthesized in air. The reaction formula is 2co+H2+ 1.5o2 → 2ch2o, and the flame temperature is about 2500℃. The longer the outer flame, the better the effect of protecting the cutting oxygen flow.
When setting the slit compensation of CNC cutting machine, there are the following points that need our attention:
1, if the software compensation is set in advance, then it is generally not necessary to compensate on the numerical control system in the future, otherwise it is easy to compensate the repeated size, and the result will be biased. However, if the size is almost compensated by software after cutting, the compensation can be realized by numerical control system.
2. After the compensation amount is set to zero in the software, the CNC system can realize compensation.
3. Cut out a rectangle on the waste, measure the actual size and the programmed size, and calculate the required compensation amount, so you don't need to worry even if you are not sure how much size should be compensated.
4, CNC system also has some difficult problems, such as small arc compensation is more difficult to deal with. At this time, we need to think of other ways. When the arc is smaller than the compensation radius, the numerical control system can't cut it out and can't realize the correct compensation (theoretically, the radius becomes negative). In this case, we should consider modifying the part drawing or using software compensation to find and solve the problem in time.
Extended data:
For the programming of cutting trajectory of NC cutting machine, the walking direction and starting position of the trajectory will directly affect the final cutting quality. Generally speaking, an excellent cutting trajectory should ensure good cutting quality and minimize cutting time and gas consumption. For example, when plasma cutting, try to reduce the empty distance of the gun and save time. When flame cutting, because the flame is empty and does not turn off, reducing the distance means reducing the gas consumption.
One: First, arrange the sequence and direction of cutting trajectory of CNC cutting machine. In principle, graphics with inner and outer contours should be cut first, and then the outer contour. In the cutting direction of the outer contour, the part with less reserved part should be cut first. If there are many kinds of parts cutting and blanking on a board, the cutting sequence should minimize thermal deformation, and be arranged in a unified order according to the order of first small and then large, first inside and then outside.
Second, the setting of lead-in and lead-out lines for cutting. In order to achieve good cutting effect, it is suggested that users set lead-in lines and lead-out lines when editing cutting trajectory. If the requirements for the workpiece are not too high or there is post-processing, it can be directly cut without lead. The principle of lead setting is to break a track and extend it into the reserved area or waste. The length of the lead should be at least greater than the width of a seam.
Third: Finally, slit compensation. The cutting mode, cutting thickness and cutting speed of CNC cutting machine need to be considered comprehensively, and the compensation amount is the general kerf width. Generally speaking, if the flame cutting is greater than 10mm, the plasma cutting is less than 6mm, and the seam width is about 2mm, the compensation amount can be1-1.2mm. If it is particularly accurate, users are advised to try cutting and measure the seam width.
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