With the wide application of CNC lathes in production, operators must select cutting parameters in real-time under the human-computer interaction state. Programmers must be familiar with the principle of determining cutting parameters, so as to ensure the processing quality and efficiency of parts, and give full play to the CNC machine tools. Advantages to improve the economic efficiency and production level of enterprises. However, the current cutting parameters are often determined by the process designer by experience or within a rough range. During the machining process, the selected cutting parameters are adjusted according to the situation, that is, the selection of the cutting parameters mainly depends on the process. The level and experience of personnel, with a certain degree of blindness, the lack of theory and experience often make CNC machine tools unable to operate under reasonable cutting parameters. Therefore, this paper analyzes the influence of three main factors, such as spindle speed n/(r/min), feed rate F r /(mm/min) and depth of cut ap /mm, on the surface roughness of aluminum alloy machining by cutting test. Thus looking for an optimized combination of cutting parameters.
1 Test equipment and cutting conditions (1) Test equipment CK6136 CNC lathe has high rigidity, small thermal deformation, low spindle temperature rise, low vibration, large cutting torque, and can adapt to strong cutting characteristics. It can turn inner and outer cylindrical surfaces, conical surfaces, circular surfaces, grooving and machining various threads.
Operating system: Guangzhou CNC 928TE system measurement data Main equipment: Roughness comparison block Processing object: 102 aluminum bar, diameter 36 mm test tool: CCGT09T304-AK; alloy blade; machine clamp bar (2) cutting conditions are mainly considered The factors include speed n, feed rate F r and depth of cut ap, respectively, taking three sets of experimental data, n taking 1000, 600, 1200; F r taking 0.11, 0.16, 0.28; ap taking 1, 1.5, 2.
Test scheme: In the first step, the cutting depth value is changed under the condition that the spindle rotation speed and the feed speed are constant; the second step is to select the cutting depth with the best surface quality in step one, and keep the spindle rotation speed and the cutting depth unchanged. The speed is tested; in step 3, the optimum feed rate of the surface quality in step 2 is selected, the feed rate and the cutting depth are kept unchanged, and the spindle speed is changed for testing; 2 test results and discussion are obtained by data acquisition of step one. The change in cutting depth does not substantially affect the quality of the processing. At this time, when the spindle speed is 1000, the quality of the cutting is relatively good. However, it does not mean that the higher the speed or higher than this speed, the higher the quality, which is affected by various conditions such as cutting material, tool material, and maximum spindle speed. In many aspects, the spindle speed is generally 1000, 1200 or 600.
Through the data acquisition of step 2, the feed rate affects the processing quality, the feed rate is from 0.28 to 0.16, the time for cutting the same length is increased by nearly 70%, and the surface quality is nearly doubled. However, too slow a feed rate will reduce the processing efficiency. Therefore, when selecting the feed value, it should be considered comprehensively.
Through the data acquisition of step three, it is known that the spindle speed has a great influence on the processing quality, and the surface quality of the spindle speed is better. However, comparing the data of step one, it is found that the rotation speed is reduced to a certain extent, and the influence on the surface quality is gradually weakened.
From the above data, we can only visually see the influence of each parameter on the processing quality. In order to draw conclusions more scientifically and accurately, we must also use mathematical tools for theoretical analysis to obtain a correct database of cutting parameters.
3 Determination of cutting parameters in CNC turning In the selection of NC programming, when determining the cutting parameters, the machining quality and tool life of the workpiece should be guaranteed, the ability of the CNC lathe can be fully utilized, the cutting performance of the tool can be maximized, and the cutting performance can be obtained. Production efficiency and lower production costs.
3.1 Prioritize the spindle speed Select the spindle speed to form the required cutting speed, so the spindle speed should be determined according to the allowable cutting speed and the bar diameter. From the performance of the experimental process, in addition to the threading process, the CNC turning spindle speed is basically the same as the normal turning machining, and should be based on the diameter of the part to be machined on the part, and according to the cutting speed allowed by the conditions of the part and the material of the tool. determine.
In addition, consider the rigidity of the lathes of different specifications, and select the closer rotation speed within the maximum speed range that the machine can withstand for final determination. The spindle speed override switch is generally provided on the control panel of the CNC system, and the spindle speed can be adjusted in multiples during the machining process. Note: When the cutting process is dry cutting, the spindle speed should be selected smaller, taking 70% 80% of the cutting fluid. In production, the spindle speed can be calculated by the following formula: 1000 /Ï€n vd = :v is the cutting speed, mm/min; d is the surface diameter of the part to be machined, mm.
3.2 Selection of feedrate feedrate refers to the distance that the tool moves along the feed force in unit time, such as mm/min. Some CNC machine tools use the feed rate per revolution mm/r to indicate the feed speed and determine the feed speed. The principle is as follows: (1) Under the premise that the machining accuracy and surface roughness quality requirements of the workpiece can be guaranteed, in order to improve production efficiency, the feed rate should be as high as possible; (2) cutting, turning deep holes or using When the high speed steel tool is turning, it is better to choose a lower feed speed; (3) the tool idle stroke, especially when returning to zero at a long distance, can set the feed rate as high as possible; (4) the feed speed should be the same as the spindle speed The depth of cut is adapted.
According to the experimental results and related data, non-ferrous metals select the feed according to the surface roughness requirements.
3.3 Selection of cutting depth The cutting depth should be selected according to the rigidity of the process system composed of machine tools, fixtures, tools and workpieces, and the accuracy of the workpiece surface and surface roughness. Under the permissible conditions, a larger cutting depth should be selected as much as possible to reduce the number of passes and improve the processing efficiency.
When the machining accuracy and surface roughness requirements of the part are high, consideration should be given to leaving an appropriate finishing allowance. The finishing allowance is generally smaller than the ordinary turning allowance, usually 0.1 to 0.3 mm. In addition, according to the experimental data, in general, when the surface roughness value Ra12.5 is processed, a roughing can reach the requirement. However, when the machine tool has poor rigidity, insufficient power or excessive margin, the machining can be completed by multiple cuttings, and the amount of knife should be gradually reduced with the number of passes; when the surface roughness is required to be Ra1.0~1.6, then A smaller amount of cutting is used to complete the finishing.
4 Conclusion Through the test data, the influence of spindle speed, feed speed and depth of cut on the surface quality of the machined workpiece is obtained. At the same time, through the comparative analysis method, it is found that when the cutting material is aluminum alloy, the influence of the cutting depth on the surface processing quality is not significant, and the influence of the feed rate on the processing quality is remarkable. In turning, the spindle speed and feed rate generally have empirical values ​​for reference. The spindle speed is n=1200 r/min and the feed rate F r=0.11 mm/min. For the depth of cut, the margin is Machine tool stiffness, power size, etc., should be determined according to specific circumstances.
In summary, the various elements in the machining process are interrelated and mutually constrained. The operator should comprehensively consider the relationship between the various elements according to the actual processing needs, and select the best combination of parameters to achieve the desired. Processing effect.
(Finish)
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Product description:
The material used partly determines the extent of thermal conductivity. Copper and aluminum are the most widely used materials, though aluminum is the more common choice because copper is more expensive and heavier. Aluminum 6061 and 6063 are widely used with a thermal resistance of 166 and 201 W / mK, respectively.
More services we offer:
Besides of Metal Stamping components,the Amplifiers metel chassises and Panels, we also complete solution for OEM/ODM products & components, offer services of deep drawing services, EMI metal shielding parts, heat sink ,plastic molding products for custom, PVC fittings ,pvc conduit fittings, plastic injection components, Metal Stamping Parts, home appliances accessories ,R/C drone and smart electronic toys etc.
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