Under the condition that modern large-scale high-speed processing equipment is more and more applied to the production link, how to select the appropriate Er toolholder to adapt to the progressive spindle speed of the machine tool and process the high-precision mold surface, the technical staff must comprehensively consider the various characteristics of the toolholder, especially the clamping force and radial runout error accuracy and dynamic balance quality under the condition of high-speed operation This is helpful to reduce the vibration of the tool itself. It is reported that the radial runout error accuracy of general toolholder is less than 3 μ M. considering the runout error of machine tool spindle, the combination of low weight spindle, toolholder and tool is conducive to better cutting effect.
Generally speaking, customers will put forward clear requirements for the cutting effect of Er toolholder. Because different systems have different technical characteristics and advantages, according to the special application purpose of customers, a perfect tool clamping system can be found.
Selection of tools for hole machining: generally, there is no drilling die for hole machining of CNC machine tools. Due to the poor rigidity and cutting conditions of the bit, the diameter D of the bit should meet the condition of L / D ≤ 5 (L is the drilling depth); before drilling, the center drill should be used for positioning to ensure the positioning accuracy of hole machining; before fine reaming, the floating cutter can be used, and the hole orifice should be chamfered before reaming; When boring, the symmetrical multi edge boring head should be selected as far as possible to balance the boring vibration, and the thicker and shorter tool bar should be selected as far as possible to reduce the cutting vibration. In economical NC machining, because the grinding, measurement and replacement of cutting tools are mostly done manually, which takes up a long time, it is necessary to arrange the order of cutting tools reasonably. Generally, the following principles should be followed: ① Minimize the number of tools; ② After a tool is clamped, it should complete all the parts it can process; ③ The tools for rough and finish machining should be used separately, even if they are of the same size and specification; ④ Milling before drilling; ⑤ First, finish machining of surface, then finish machining of two-dimensional contour; ⑥ If possible, the automatic tool changing function of CNC machine tool should be used to improve the production efficiency. In addition, there is a great relationship between the durability and accuracy of cutting tools and the price of cutting tools. It must be noted that in most cases, a good choice of cutting tools increases the cost of cutting tools, but the resulting improvement of processing quality and efficiency can greatly reduce the whole processing cost. In a word, according to the heat treatment state, cutting performance and machining allowance of the workpiece material to be processed, selecting the milling cutter with good rigidity and high durability is the premise to give full play to the production efficiency of CNC milling machine and obtain satisfactory processing quality. 2) Selection of CNC milling tools: when machining curved surface parts, in order to ensure that the cutting edge of the tool is tangent to the machining contour at the cutting point and avoid the interference between the cutting edge and the workpiece contour, the ball end tool is generally used, the two edge milling tool is used for rough machining, and the four edge milling tool is used for semi finish machining and finish machining; When milling large plane, in order to improve production efficiency and machining surface roughness, insert type disc milling cutter is generally used; when milling small plane or step surface, general milling cutter is generally used; when milling keyway, in order to ensure the dimensional accuracy of groove, two edge keyway milling cutter is generally used.
February 23, 2021
