The speed of the machine tool must not only be very fast, but also the machining shape must be accurate. The CNC system must precisely control the acceleration and deceleration movements in the programmed contour machining path. In order to cope with the contradiction between processing time, surface quality and geometric accuracy, modern CNC systems must provide optimized solutions for milling machines and machining processes. And the end user can also control the final milling result with simple parameter adjustments. The path control capability of the CNC system is a decisive factor influencing the processing time under specific accuracy and surface quality conditions. Figure 1 Freeform Machining (Hyperboloid) The requirements of high-speed cutting (HSC) technology for tooling manufacturing on machine tool control systems provide many new options for machining high-hardness materials and alloy tool steels. After the classic EDM machining technology, high-speed cutting technology directly processes high-hardness materials and shows more and more excellent economy. One of the prominent advantages of HSC technology is its temperature distribution and heat removal during processing. High-speed cutting, high-speed feed, and low depth of cut allow the chips to carry a large amount of heat away from the workpiece. HSC requirements and impact The feed rate of HSC machining is large, and the acceleration of the contour of the workpiece surface is higher. It can highlight the mechanical and electrical properties of the machine. If the acceleration of the feed drive increases, the structure of the machine will inevitably undergo greater acceleration. In addition, it is also easy to cause vibration of the machine and affect the surface quality. This requires that the numerical control system has the ability to achieve the best surface quality of motion control while minimizing the processing time and meeting the accuracy requirements. The CNC system must provide machine tool manufacturers and users with the best path control methods. Machine tool builders need CNC systems to optimally control the characteristics of the machine. The CNC system should provide parameters for the motion control and feed drive motor control loops, and have a reasonable structure. The machine tool often evaluates the performance of the final machined part. Every machining task must be performed to ensure that high dynamic response does not cause machine vibration. Therefore, the CNC must work closely with the machine to ensure high dynamic performance for any machining task. CNC machine users demand that the CNC system can reduce the processing time on the premise of meeting the accuracy of the workpiece. To achieve the required accuracy without requiring time-consuming testing, the first piece of processing must be able to meet the requirements. These requirements must be defined in the NC program to ensure mass production requirements. Moreover, free-form surfaces are often milled using a reciprocating path in order to control the processing time of the mold within an acceptable range. In this way, the CNC must also be able to generate reproducible tool paths that process contours from opposite directions. Otherwise, the surface quality will be damaged. The influence of data processing ability on the surface quality of workpieces. Processing of parts with metal cutting involves a large number of intermediate steps. Through these steps, CAD model geometry is converted into a tool path; CAD (Computer Aided Design); CAM (Computer Aided Manufacturing); CNC ( Computer digital control); electromechanical systems. Optimizing the machining time, surface quality and workpiece accuracy puts forward the following basic requirements for the CNC system: effective monitoring of contour tolerances; accurate repetition of adjacent paths after the direction of movement is reversed; high dynamic motion will not cause vibration. For 2D tool motion, the influence of the data processing chain capability on the accuracy of the workpiece can be detected with a KGM182 2D encoder from HEIDENHAIN. The motion control features of the HEIDENHAIN iTNC 530 system can be displayed using the demonstration unit on the portal milling machine. KGM is the basic inspection tool that can finally achieve contour accuracy. Figure 2 Ball cutter TCP tool path Faster, more accurate and more accurate contours An NC program that effectively controls contour tolerance free-form surfaces is usually generated using the CAM system, which consists of a large number of simple line segments. HEIDENHAIN controls automatically smooth the transition shape while maintaining continuous movement of the tool on the workpiece surface. This system internal function for detecting contour deviation can automatically control the smoothing process. On a free-form surface, the deviation of the CAD geometry model includes the defined contour tolerance value and the difference in chord height defined by the CAM system. The final effect on the workpiece depends on the machine's overall characteristics and the feed axis acceleration adjustment and acceleration. The path control function of the iTNC 530 smoothes the acceleration and satisfies the contour tolerance requirements, even when the contour machining speed changes drastically (Figure 3). If you can define larger tolerances, you can significantly reduce the processing time. In this example, the contour machining tolerance was relaxed from 0.01 mm to 0.02 mm, and the machining time was shortened by 12%. Fig. 3 is a partial enlarged view showing TCP's profile monitoring nominal path Figure 4 shows the effect of optimizing motion control. The free-form surface is machined with reciprocating motion (programmed feed rate is 10m/min, fine milling allowance is 0.1mm). The workpiece surface quality of Figure 4a is not qualified. The results of the machining with the iTNC 530 system are shown in Figure 4b, and the adjacent paths are reproducible. a b Figure 4 Multi-taper milling for commutation motion, repeatability of adjacent cutting paths 4a: Surface quality degradation due to adjacent path deviations 4b: iTNC 530 system Milling results: Surfaces of forward and reverse motion machining are the same The feed rate required by the HSC milling technology is a great challenge to the CNC system of the machine tool. Only reaching a higher average speed of the contour machining can shorten the processing time. However, if there is a small radius path, the speed must be greatly reduced to ensure that the path deviation is within the allowable tolerance band. In addition, acceleration and deceleration movements can also cause vibration of the machine structure and damage the surface quality of the workpiece. The smooth movement control of acceleration and acceleration is the outstanding feature of HEIDENHAIN CNC system. It can suppress machine vibration very effectively. According to need, the numerical control system can also automatically reduce the programming feed rate to minimize the risk of vibration. Effectively preventing machine vibrations allows part programs to be executed at higher speeds, thus significantly reducing machining time. Figure 5 Actual position is measured and recorded at the corner using a 2D encoder, one uses a nominal position filter to process NC data, and the other does not use a nominal filter (5a and 5b, respectively) Figure 5 shows the actual path of a 2D contour machine tool. If there is no smoothing at the speed increase, the machine tool will vibrate during acceleration (Figure 5a). The movement control function of HEIDENHAIN iTNC 530 systems can effectively avoid severe vibration (Figure 5b). The workpiece surface quality in Fig. 6 clearly shows once again the extraordinary function of the motion control functions of the HEIDENHAIN CNC system. Movement along the illustrated circular arc requires changing the acceleration of the shaft at each point, causing the machine to vibrate (Figure 6a). The iTNC 530 achieved a high quality surface by speeding up the smoothing process with no vibration effect (Figure 6b). a b Fig. 6 Effect of machine vibration on the workpiece surface: 6a: No speed-up smoothing, Z-axis vibration causing surface scratches 6b: The motion control function of the iTNC 530 system effectively avoids surface quality problems caused by vibration HSC milling technology has a decisive influence on the manufacturing processes of the mold manufacturing and aerospace industries. The feed rate required by the HSC milling technology is a huge challenge for the CNC system. Processing time, contour surface accuracy and surface quality are mutually contradictory factors, and the HEIDENHAIN iTNC 530 CNC system ensures that optimal machining requirements are met. As a result, machine vibrations can be prevented, high precision requirements can be satisfied, and machining time can be shortened. In addition, the iTNC 530's adjacent milling paths are highly repeatable, ensuring that the user can achieve high-quality workpiece surface machining and reduce the machining time with a reciprocating multi-knife milling process. The iTNC 530 has set a new standard for the coordination of CNC, drive and machine tool structures. Makes the user's batch part production from the first piece can achieve high-quality processing results. Extrusion Blow Molding Machine Extrusion Blow Molding Machine,Plastic Extrusion Molding Machine,Plastic Extrusion Blow Moulding Machine,Automatic Extrusion Blow Molding Machine JIANGYIN HENTOL NEW MATERIAL CO.,LIMITED , https://www.hentolgroup.com
Mould manufacturing and parts processing in the aerospace industry can be optimized with modern high-speed cutting (HSC) technology. If you want to achieve the economical purpose of high-speed cutting technology, it is necessary to make machine tools and numerical control systems able to cope with higher speeds than conventional cutting methods.