Accuracy analysis of machining slender rod-shaped tools by CNC machine tools: the improvement of the accuracy of rod-shaped tools has always been a difficulty in tool manufacturing. The main reason is that the effective part of the tool is too long and the cutting edge of the tool is too far from the clamping part during manufacturing. Because the cutting edge is too far away from the clamping part, and the chuck has certain clamping accuracy (generally 0.002 ~ 0.005mm), the radial circular runout at the cutting edge of the cutter may have reached 0.005mm ~ 0.01mm (or even greater) before grinding. Due to the large grinding force and the large elastic deformation of the tool, there will be many problems in the machining process, such as the asymmetry of the tool groove, the size of the tool’s outer circle, the parameters of the cutting edge and the shape error are not up to the requirements, and even the tool is broken in serious cases. The following is a simple analysis of the accuracy of the tool when machining slender rod-shaped tools with CNC machine tools.
1、 The influence of machine tools on tool accuracy. The influence of machine tool accuracy on tool accuracy the accuracy of machine tool is the key to determine the accuracy of any tool, and the slender rod-shaped tool is no exception. The support block equipped with this machine tool is mainly used for CNC machining slender rod-shaped tools. Its position can be adjusted in the horizontal and longitudinal direction, and can be positioned according to the actual situation. If the position of the support block in the transverse direction (i.e. the axial direction of the tool) is not reasonable, the qualified slender rod-shaped tool cannot be machined. If the support block is too low, the support force to the tool is not enough, which will cause the tool groove to form an inverted cone in the axial direction; if the support block is too high, the support block will force the tool against the tool, which will lead to the tool groove forming a cone along the axis. Therefore, the accurate positioning of the support block is also very important to the accuracy of the tool.
2、 The influence of CNC grinding wheel on tool accuracy. All parameters of the cutter are determined by the relative motion between the grinding wheel and the cutter. Therefore, the diameter of the grinding wheel, the angle of the grinding wheel directly participating in the cutting, the flange length of the grinding wheel shaft, the wear of the grinding wheel and the grain size of the grinding wheel all affect the accuracy of the cutter. The accuracy of grinding wheel angle measurement or input may cause: the width of cutting edge belt does not conform to the requirements; the angle of stepped cutter’s step surface does not meet the requirements; the position or angle of tool back angle has error; the groove angle of chip removal groove has error.
3、 The cooling effect of the coolant on the grinding area will directly affect the accuracy of the cutting tool when machining hardware parts. The selection of coolant with good performance and proper cooling pressure is conducive to the coolant entering the grinding zone, which can take away the cutting heat and chips in time, and effectively reduce the surface roughness of the tool.
CNC punch press is a kind of equipment which can automatically blanking sheet metal according to the NC machining program. The ideal processing program should not only ensure that the hardware parts can be processed to meet the design requirements of qualified parts, but also can make the CNC punch get reasonable application and give full play to its performance.
With the development of stamping equipment, more and more numerical control blanking technology is used. Through the research and analysis of the process characteristics of numerical control processing, this paper puts forward some matters that should be paid attention to in the program design of numerical control punching, and illustrates the correct method to complete each work with corresponding examples. The author of the article has rich practical experience, because some articles have strong practicability.
When designing numerical control program, whether it is manual programming or automatic programming, it is necessary to analyze the processing technology of hardware parts before programming, and then work out the processing scheme, formulate the correct and reasonable processing process, and select the appropriate mold and processing speed. In the design of numerical control program, hardware processing plant should pay more attention to some process methods of program design. If some process details are ignored, sometimes even if the processing program is correct, due to the unreasonable process method of the program, it is impossible to process qualified parts. What’s more, it will cause alarm and damage to the machine tool.
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