Problems that should be paid attention to in the N

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Problems that should be paid attention to in the process of NC transformation of machine tools

[electromechanical news] at this stage, China's industrialization has just entered the medium-term development stage, and the strong development momentum of heavy industries such as coal, steel, building materials, machinery, electronics, chemical industry, real estate, etc. holds great development opportunities for the NC machine tool industry. Luo Baihui, Secretary General of the International Mold Association, said that in China's market, the market share of domestic mid-range CNC machine tools is only 35%, and more than 95% of high-end CNC machine tools are mainly imported; Compared with the international advanced level, the stability and reliability of product quality still have great room for development. Excessive technology dependence leads to the lack of high-tech support in the industry, which lags behind the independent innovation development of industries with large monthly changes in export value. The 12th Five year development plan of machine tool industry points out the existing problems and the situation faced by China's CNC machine tool industry

in addition, the rapid development of China's CNC machine tool industry and the continuous enhancement of its overall strength have significantly improved the international status of the CNC machine tool industry. In the face of such an attractive Chinese market, how can a powerful CNC machine tool manufacturing country be expected to fail; The tide of returning to manufacturing triggered by the post financial crisis has prompted a new round of industrial restructuring supported by high-tech. In the complex and volatile market environment at home and abroad, if there is no independent research and development of high-tech, the CNC machine tool industry can only hope to seize the huge development opportunities

due to the characteristics of high machining accuracy and high productivity of CNC machine tools, the application proportion in the manufacturing industry is increasing, effectively ensuring the product quality and output. Purchasing new numerical control machine tools is the way to improve the efficiency of numerical control of machine tools, and the numerical control transformation of old machine tools is also an important way to improve the efficiency of numerical control of machine tools. The NC transformation of machine tools can reduce the cost of purchasing NC machine tools and save funds for enterprises. In recent years, with the expansion of the transformation demand of various types of domestic machine tools, machine tool transformation has gradually formed an industry, most of which are the numerical control transformation of old numerical control machine tools, and some are the numerical control transformation of ordinary machine tools. Now the problems that should be paid attention to in the process of NC transformation of machine tools are introduced as follows for your reference

I. cost performance analysis of NC transformation and renewal of machine tools

before NC transformation of old machine tools, the price of NC machine tools with the same performance in the market should be investigated. When comparing the two prices, we should also consider the supply time. For small CNC lathes and milling machines with low prices, it is recommended to update and purchase new machine tools instead of transforming old ones. Because the cost difference between the two is not much, less money is saved, and the transformation time of the machine tool is about 2 months. For small CNC lathes and milling machines, machine tool manufacturers generally have stock. For large and expensive machine tools, numerical control transformation is a better choice, which can not only save more money, but also shorten the purchase time. For example, a horizontal machining center with a worktable size of 2000x1800mm, three-axis linkage and 60 cutters is compared as follows

second, investigate the current situation of machine tools that need to be transformed

not all old machine tools are suitable for NC transformation. We should have a comprehensive understanding of machine tools that need to be transformed

the mechanical system of the machine tool should be surveyed and mapped to make a correct judgment. Good mechanical performance is the basis for the successful NC transformation of the machine tool. 3. The exposed sliding parts, gears, pulleys, etc. of the experimental machine should have protective mounting parts, otherwise, the best NC system cannot play its due performance. Therefore, the mechanical accuracy of the machine tool should be tested before the NC transformation of the machine tool, and the problems found can be repaired during the implementation of the machine tool transformation. If there are many problems in the mechanical system of machine tools, such as defects in the mechanical structure design and manufacturing of old machine tools, the NC transformation of machine tools will not be of great significance

the electrical system of old machine tools continues to fail due to aging components, which is the key work of machine tool transformation. You should know the manufacturer model of the old machine tool CNC system, the number of control shafts, the drive configuration of the spindle and feed shaft, the power of the spindle motor, the torque of the feed shaft motor, etc

check whether the accompanying technical data are complete. Complete technical data can shorten the technical preparation time of machine tool transformation. Among them, we should carefully study the electrical schematic diagram, PLC program, machine tool maintenance manual, hydraulic, pneumatic, lubrication schematic diagram, mechanical assembly diagram, etc. Special attention should be paid to that the contents provided in the technical data may be incorrect and inconsistent with the physical object of the machine tool. This is because some machine tool manufacturers provide general drawings of series models, and the electrical hardware changes of individual machine tools are not marked on the electrical data, which requires us to carefully check against the actual machine tools to avoid mistakes

III. determination of NC transformation scheme of machine tool

on the basis of Surveying and mapping of machine tool, determine the overall transformation scheme of machine tool according to the requirements of users

1. Transformation scheme of numerical control system

the transformation of machine tool is the transformation of numerical control system. According to the existing control level of machine tool, workpiece processing requirements, enterprise capital status, select the corresponding low, medium and high-grade numerical control system. When selecting CNC system, we need to consider the products of mainstream manufacturers. For example, FANUC and Siemens systems can be selected for foreign CNC systems, and Huazhong and caiente systems can be selected for domestic CNC systems. It should also be consistent with the CNC system selection of other existing CNC machine tools as far as possible. The advantage of this is that it is convenient for maintenance personnel to maintain the machine tool daily; The more centralized CNC system is also convenient to reduce the types of spare parts

the selection of CNC system is based on the principle of practicality, and there is no need to waste money in pursuit of a higher level

2. Transformation scheme of spindle servo system

the spindle control of old CNC machine tools generally adopts DC servo or AC analog servo drive system (generally +/- 10V analog signal). According to the use requirements, the original drive device and spindle motor can be left, and the AC digital servo drive system can be used instead or controlled by frequency converter. It can also retain the original drive system, such as the new optimized renewal flow simulation servo drive system of the alternating regeneration plastic granulator in good condition; The DC servo drive system can retain the DC motor in good condition, and use the new DC servo control device to replace the old drive device

3. The transformation scheme of the feed servo system

is similar to the transformation scheme of the spindle servo system. According to the use demand, the original drive device and motor can be not retained, and the AC digital servo drive system can be used instead; The original drive system can also be retained, such as the AC analog servo drive system in good condition

4. Transformation scheme of closed-loop control detection device

for the inductosyn/ruler of the old machine tool, circular grating and grating ruler can be used to replace it. When selecting the type, pay attention to the consistency of the interface signal between the detection element and the system, square wave signal or voltage signal. If the grating ruler of the old current signal is retained, the conversion device from current signal to voltage signal needs to be added to match with the new system, because most of the new systems do not support current signals

(source: Luo Baihui: he Minnan)

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