What are the causes of CNC products?
When machining steep contour surfaces, ZLEVEL contour milling is usually used to remove material along the part contour in the plane cutting layer perpendicular to the tool direction, as shown in figure 4. In high-speed processing, although you can use the ZLEVEL contour milling, but in the transition layer and layer, cutting and vertical steering, the knife will cause the tool vibration becomes larger, the tool is easy to break and the surface quality is not high, there will be obvious signs of cutting tool. It is recommended to use surface area drive and change slicing method into helical cutting method. Specific methods are as follows: first create an auxiliary cylinder (Fig. 5), using the surface area drive operation, the specified rotating body is cylindrical body parts, specify just established for driving, driving in the establishment of lattice cylindrical surface, and then define the cutting direction, select horizontal cylindrical surface of the upper part of the for the first time cutting direction, a small circle in the selected arrow, return to the surface driving method dialog box. Cutting drive lattice set for the spiral tool path, and then through the driving point along the direction of the part surface projection vector projection, the projection vector direction pointing straight, the middle axis line set for rotary parts, arranged as shown in figure 6. A cylindrical spiral cutter rail is projected onto the workpiece according to a projection pointing to the middle axis so that a helical rail of the cutting workpiece contour can be produced, as shown in figure 7. This process of tool path generation is relatively complex, but the biggest advantage is the spiral drive, from a tool trajectory to a tool path, moving smooth and smooth, no sudden change, so the whole process of cutting speed can be maintained constant. For this reason, the screw drive is suitable for high speed machining
(1) a tool with a rounded radius is smaller than a corner radius; this method is only relatively small.(2) knife rail fillet processing, the effect shown in figure 2. The plane contour milling in CAM NX, the specific operation rate control options in the corner and feed, add when set convex arcs, convex cutter milling process encountered by circular arc cutting processing, the circular arc is convex top, radius of cutter diameter. A fillet can also be added to the side wall, as shown in figure 3. This process has not pause at the boundary of the workpiece, the tool movement provides a smooth arc transition and continuous (G02 or G03), and then tick in the deceleration setting, the system at the corner of the tool set deceleration operation. These settings greatly reduce the effect of vibration reduction.3) circular interpolation produces slightly larger fillet radii than specified in the drawings. In this way, it is sometimes possible to use larger tools in rough machining to maintain high production efficiency. In the corner, the remaining machining allowance can be reduced by fixed milling or circular interpolation cutting with smaller tools.
In traditional programming, the cutting angle is achieved by using linear cutting (G1), and the transition in the corner is not continuous enough, as shown in figure 1. When the tool reaches the corner, the tool must slow down due to the dynamic characteristics of the linear axis. Before the motor changes its feeding direction, there is a short pause which causes a great deal of heat and friction, which results in instability of the cutting force (commonly known as a knife) and often cuts the corners. The bigger the tool or the longer the tool overhang, the stronger the vibration. This is a difficult point in programming.
In the field of NC machining, machining centers, CNC milling machines and engraving machines have been widely used in high-speed machining. In high speed machining, spindle rotation speed is usually in the 1-2 million revolutions per minute, the tool feed speed and spindle speed is proportional to move very quickly, and CNC milling and boring than simple turning force is more complex. In this case, tool vibration becomes a very important factor in cutting. Many factors caused by vibration of tool, tool form and material, workpiece materials, cutting parameters and cutting path will cause vibration of the tool, this paper from the cutting path to talk in the use of NX software to CAM programming, some techniques to reduce the tool vibration.
