Research on NC Transformation Based on CA6146 Lathe
Research on NC Reform of CA6146 Type Lathe Based on Journal of Dongguan University of Technology Li Qi (Department of Mechanical and Electrical Engineering, Dongguan University of Technology, Dongguan 523106, China) Enterprises need to be rapidly updated and developed in the current market with changing market demands and fierce competition. New products, with the lowest price, the best quality, the shortest time to meet the changing needs of the market. While ordinary machine tools are not suitable for multi-variety and small-volume production requirements, CNC machine tools integrate advanced technologies such as numerical control technology, microelectronics technology, and automatic detection technology. They are most suitable for processing small batches, high precision, complex shapes, and short production cycle requirements. Components. When changing the machining object, only the part processing program needs to be changed, and no adjustment to the machine tool is required, so that the processing requirements of frequently changing products can be well satisfied. CNC lathes are used more and more in the machining industry. The development of CNC lathes is full-featured and high-performance on the one hand; on the other hand, it is a simple and practical economical CNC machine tool with basic functions of automatic machining, which is convenient for operation and maintenance. The economical numerical control system usually uses an open-loop step control system. The power stepping motor is a driving component, and there is no detection feedback mechanism. The positioning accuracy of the system is generally up to ±0.01 to 0. It can meet the processing parts of the C6146 lathe after the transformation. Precision requirements. After many overhauls, the size of the components of the ordinary lathe has changed greatly. The main transmission parts have been replaced and adjusted several times, and the failure rate is still high. It is difficult to meet the overhaul acceptance standard with the traditional repair scheme, and the cost is high. Therefore, the rational selection of the CNC system is the main link for the success of the transformation. The purpose of the transformation of the CNC lathe is to require the machine to be stable and reliable to operate at the lowest possible failure rate. The transformation of the ordinary lathe with the microcomputer control system can improve the process level and product quality and reduce the labor intensity of the operator. This paper introduces the design ideas and methods for the NC transformation of the CA6146 lathe. 1 The choice of microcomputer control system At present, there are many types of CNC systems on the market. Before choosing, the first thing to do is to have a full understanding of the functions of the CNC machine tool to be modified. The CNC system can be selected according to the principle of reasonable price, advanced technology and convenient service. In the case of economic ability, try to use brand-name products. This kind of numerical control system has strict screening of parts, reliable manufacturing process specifications, equipment failure caused by electrical component failure or premature failure, and has excellent preventive effect. And pay attention to the function selection of the CNC system. The high-performance index of the CNC system should not be pursued purely, which is very important for achieving a high performance-price ratio. The function of the numerical control system should match the function of the CNC machine tool that is ready to be modified. J minimizes the excessive numerical control function. Because of the excess function of the numerical control system, on the one hand, it is a waste of funds, on the other hand, it may also lurk under the hidden trouble of the increase of the failure rate due to the increase of the complexity of the numerical control system. Therefore, it is more suitable to select the GSK/928T CNC system according to the structure, performance and machining accuracy of the CA6146 lathe. The control computer of the system uses a high-speed microcomputer processor shore conductor memory and a parallel interface circuit. The driving part adopts transistor PWM drive circuit, and the whole system belongs to open-loop control. The structure is simple, the driving force is large, the price is low, the anti-interference performance is strong, the quality is stable and reliable, and the installation and debugging are convenient. In particular, the teaching programming function is directly oriented to the operator, which is very suitable for medium and small batch production. 2Reconstruction of the mechanical part In order to give full play to the technical performance of the GSK/928T numerical control system, the lathe after the transformation is guaranteed to repeat the positioning accuracy under the system control, the microcomputer feeds without creeping, the service life is long, the appearance is beautiful, and the mechanical part is modified as follows. . 2.1 In order to make the modified machine tool have higher starting rate and precision retention, in addition to reducing electrical and mechanical failures as much as possible, the wear resistance of machine parts and components should be fully considered, especially the resistance of machine tool guides. Grinding. At present, most of the large-sized parts such as the bed of CNC machine tools at home and abroad use ordinary cast iron. The guide rails are made of hardened alloy steel, which is 5 to 10 times more wear resistant than ordinary cast iron rails. According to this, the old bed was used in the transformation, and the guide rail was made of GCR15 bearing steel and hardened to HRC56-62, and fixed on the cast iron bed with screws and adhesive. The working surface of the guide rail before the bonding is ground with a surface roughness Ra0. 8 mm to improve the bonding strength. 2.2 The main shaft gearbox adopts GSK/928T numerical control system. The main motion mode requires a very competitive shift range as well as the conventional machine tool to ensure a reasonable speed during machining to achieve higher productivity and surface quality. According to the specific conditions of the original headstock shifting, the 16 kinds of spindle shifting functions S input by the numerical control system are effectively utilized. Only the two shafts 56 and 51 on the I-axis and the 34 and 39 double-coupling gears on the shaft are divided. For the second, the DLM3 control electromagnetic clutch is installed on each of 56 and 51, so that the two speed adjustments can be completed according to the shifting command issued by the system without stopping the machine. The adjustment of other speed groups can be adopted by the parking waiting to be started command in the system. The original manual mechanical shifting was completed. See the modified part of the drive. 2.3 The drive part of the modified board is the object of direct control of the GSK/928T numerical control system. Whether it is point control or continuous control, the final coordinate precision of the machined part will be affected by the movement accuracy, sensitivity and stability of the carriage. . This is especially true for open loop systems that use stepper motors as drag elements. Because the command issued by the CNC system only moves the carriage without position detection and signal feedback, the actual movement value and the system command value will cause machining errors if there is a difference. Therefore, in addition to the higher accuracy requirements of the carriage and its accessories, the following measures should be taken to meet the transmission accuracy and sensitivity requirements. (1) Use the reduction gear box on the layout of the transmission to improve the transmission torque and transmission accuracy (resolution is 0.01mm>. The calculation formula of the transmission ratio is: (2) In the gear transmission, in order to improve the accuracy of the forward and reverse transmission As far as possible, the transmission gap between the mating gears can be eliminated. There are two methods: flexible adjustment method and rigid adjustment method. The flexible adjustment method refers to the method that the gear backlash can be automatically compensated after adjustment, in the tooth thickness and teeth of the gear. In the case of difference in distance, there is still no backlash engagement, but it will affect the smoothness of the transmission, and the structure of this adjustment method is more complicated, and the transmission rigidity is low. The rigid adjustment method 22 Journal of Dongguan University of Technology in 2003 refers to After the adjustment, the adjustment of the gear backlash can not be automatically compensated. It requires strict control of the tooth thickness and pitch error of the gear, otherwise the flexibility of the transmission will be affected. However, the gear transmission adjusted by this method has better transmission rigidity. Moreover, the structure is relatively simple. The paired gear backlash method applied in the equipment modification is a rigid adjustment method. (3) Using the ball screw instead of the original sliding screw to improve transmission sensitivity and reduce power, stepper motor torque loss. 2.4 Automatic tool changer In order to meet the functions of multi-step machining and application of GSK/928T numerical control system in one lathe on one lathe, after many investigations and trials, the WZD4 automatic tool post was finally determined. The tool holder can be used not only as a substitute for the ordinary lathe manual tool holder but also as a microcomputer control element for the numerical control machine tool. The tool holder has small volume and high repeatability, and is suitable for powerful turning and safe and reliable. 2.5 The pallet box is controlled by GSK/928T numerical control system. Remove the original tow box and use this position to install a new tow box. In addition to the nut of the fixed ball screw, the new tow box is equipped with a storage tank and a hand pump for lubricating the screw pair. The hanging wheel box and the cutter box are removed, and the spindle pulse encoder for controlling the thread processing and the power stepping motor and the speed reducer for the axial servo component of the carriage are respectively installed at the two positions. Make the modified machine tool look beautiful and reasonable. After the transformation, the start and stop of the machine tool are completed by the numerical control system, so the original machine tool joystick, the levers such as the turning bar and the vertical shaft are removed. 3 Conclusion After the modification, the CA6146 lathe not only maintains the wide range of shifting range of the original lathe spindle transmission part, but also can be programmed and controlled by the programming language in the lathe movement control. It can also automatically generate the operator's manual machining process in the system teaching state. ISO code for automatic machining of the next part. Practice has proved that the lathe is easy to operate, reduces the labor intensity of the operator, improves the quality of the product, and creates favorable conditions for the production of the next process. The cost of the retrofit is only half the price of a simple CNC lathe. (Finish) Creative Autumn and Winter Warm kennels and cushions and Pet Clothing and grooming tools Cats and kennels Shenzhen Ananda Technology Co.,LTD , https://www.carmitek.com