CNC machine tool repair and transformation series lecture
As a working machine and maintenance tool, machine tools have become an indispensable equipment in various industrial fields. The production and development of CNC machine tools is a powerful guarantee for the manufacture of high quality, high efficiency and high consistency products. With the rapid development and progress of human society, various new materials, new technologies, new processes, new structures, and new accessories are constantly emerging, and new requirements are constantly being raised in various fields, all of which make the structure and performance of machine tools ever-changing. The rapid development of computer technology has made the machine tool numerical control system update in a shorter cycle. Faced with such a situation, machine tool builders are constantly striving to keep track of the pace of the times, and machine users and maintainers must work hard to keep up. In order to enable readers to understand the technology and knowledge of CNC machine tools in a timely manner, and deepen the understanding of the use and maintenance concepts of CNC machine tools, this lecture was organized in an effort to help readers.
Lecture 1 An emerging industrial field - machine tool overhaul and numerical control transformation
In the development of the world economy, the machinery manufacturing industry plays an important role as a basic industry. To this end, economists and entrepreneurs in various countries are constantly exploring the development strategies of various advanced manufacturing technologies and manufacturing industries under the new situation. The machine tool manufacturing industry, which is the core of manufacturing, is the cornerstone of the pillar and is indispensable for any industry.
First, the social and economic foundation of production and development
(1) China's existing tens of thousands of old and backward machine tools are the realistic basis for the machine tool overhaul and numerical control transformation industry. China is a developing country. Due to the long-term incompatibility of its own mechanism, its economic strength is too low. Technology is backward and equipment is outdated, which greatly restricts the development of the national economy. In order to change the backwardness of China's machinery manufacturing industry as soon as possible, we have actively introduced the world's advanced technology and equipment while developing the national machine tool manufacturing industry for more than 20 years. On the one hand, in cooperation with the world's advanced machine tool manufacturers, we continue to produce all kinds of machine tools with world-class levels; on the other hand, we directly purchase a large number of various types of machine tools. All of this has played a huge role in the rapid development of China's national economy.
However, the machine tool is used for a long period of time or even overloaded, and at the same time it lacks serious repair and maintenance, causing serious wear and loss of precision of the machine tool. Some machine tools are left unused for a long time due to changes in the structure of the company personnel and products, or due to insufficient technical strength. When it is needed, it is found that it has been rusted, and the electronic control system cannot be started. Due to the needs of new product manufacturing, the original machine tool performance can no longer meet the requirements of use, and it is urgent to update and upgrade; due to the rapid development of the world's computer and network technology, CNC is caused. The product update of the system and drive system factory is accelerated, and the original products are discontinued prematurely, which brings certain difficulties to the replacement and maintenance of spare parts. Moreover, the service life of the numerical control system is generally 5 to 10 years, and most of the machine tools in China are in service. These many factors require overhaul and numerical control upgrades of machine tools.
(2) Newly-advanced second-hand machine tools have become the catalyst for machine tool overhaul and numerical control transformation industry. Since the reform and opening up, many companies have introduced a large number of old machine tools that have been eliminated from abroad. Although some of them can still meet the requirements for use, most of them lack experience. Factors such as technology, data and spare parts have created an embarrassing situation in which they are cheap to buy but cannot continue to function. Among them, there are many old machine tools and production lines that were introduced for use after the transformation. Most of the used machine tools here can be used as long as they have appropriate capital investment.
(3) Significant economic benefits are the driving force for machine tool overhaul and CNC transformation industry. For machine tool owners, the same effect can be obtained by simply purchasing less than 30% of the cost of the same new machine. According to the international industry records, even if the structural performance of the original machine tool is completely upgraded and upgraded, it only costs about 60% of the purchase of a new machine tool.
For the major companies in the machine tool modification, this not only creates huge social and economic benefits for their service companies, but also the fundamental driving force for their own survival and development.
(4) The advantages of machine tool overhaul and numerical control transformation are favorable conditions for the survival and development of the industry. Overhaul, refurbishment and upgrading of old machine tools have the following advantages compared with the purchase of new machine tools:
1 delivery time is short. Especially the advantages of large machine tools and special special machines are more obvious.
2 performance is more stable. After long-term aging, the basic parts will hardly cause stress deformation and affect the accuracy; each functional component will wear out for a long time. Functional stability and reliability.
3 design risk is small. The technical and program risks brought about by the new machine tool design are almost non-existent in the big modification.
4 can more fully reflect the wishes of the users. Users and maintenance personnel can propose improvements (including additions and changes) in machine performance, operation and maintenance in accordance with actual needs and long-term use of machine tools. They have the right to choose mechanical parts, CNC systems and other electrical equipment. Specifications, models, performance, etc.
5 is more conducive to use and maintenance. Since users and maintenance personnel can not only participate directly in the formulation of the transformation plan, but also participate in the whole process of transformation, they can directly obtain various technical information, and more deeply grasp the structure and performance characteristics of the machine tool, thereby enhancing the initiative of use and maintenance.
6 Get the latest and more practical spare parts faster.
7 save a lot of investment.
8 reduce investment risks.
(5) The trend of socialization and specialization is the only way for machine tool overhaul and numerical control transformation industry. The numerical control transformation and renovation of old machine tools is not only a necessary and important behavior in the current economic transition period, but also a strategic measure for the long-term development of enterprises.
At present, in the era of knowledge economy in the 21st century, most enterprises in China are facing enterprise restructuring, transition to enter the market economy, and rapid integration into international competition. This requires the leadership of our company to concentrate on all these forces to face these challenges. A new series of technical theories such as enterprise grouping and decentralized network, autonomy, parallel work, new organization, production structure, agile manufacturing technology, virtual manufacturing technology, sustainable manufacturing technology, green manufacturing technology, etc. Great strength to research, to develop marketable products, improve the ability to respond quickly to the market; concentrate human, financial, and material resources to enhance the market competitiveness of the company, give full play to its own advantages and create as much as possible at the fastest speed value. Therefore, it is impossible for the company itself to have a large and comprehensive maintenance team like the planned economy in the past. The socialization and specialization of equipment maintenance and transformation will inevitably become a major trend.
The transformation and refurbishment of foreign machine tools is an emerging industry that has recently developed, and has formed a certain scale and market in advanced countries. In China, this industry has only just emerged, and it is still far from being measured according to the conditions that should be met. However, people of insight in the industry are striving to shape themselves and improve themselves. I believe that in the near future, a group of specialized enterprises that have certain conditions and a certain scale of machine tool transformation and renovation will grow up.
Second, the choice of large modification plan
If this work can compete for the technical support of the modified enterprise, it may be better and faster.
1. Preparation for the preliminary project
(1) Technical feasibility analysis Mainly aim at the transformation target and processing object, and comprehensively analyze the technical status of the modified machine tool in terms of structure, performance and precision. Including whether the original structural design of the machine tool is reasonable; whether the basic components and structural parts of the machine tool are still intact; the ordinary machine tool is changed to a CNC machine tool, and it is necessary to examine whether the mechanical transmission structure of each coordinate axis and the form of the guide rail pair are applicable; The accuracy is compared with the factory precision, whether there is a gap; comprehensively summarize all the faults of the current machine tool and major faults that have occurred in history. In response to the above problems, the transformation task book is prepared according to the transformation target and the typical workpiece, so that the modified machine tool achieves certain advancement and practicability.
(2) Economic Feasibility Analysis Lists several situations that should be considered from the perspective of actual operability: from the value of the machine tool itself, whether the investment required to achieve the transformation target is too high; from the machine tool manufacturing in this unit The status and importance of the analysis of the value of the transformation; from the input and output rate of the machine tool, whether it can recover the investment faster, and then quickly produce better benefits; after the machine tool transformation, improve the accuracy of the machine tool, increase the function, whether it can enable An increase in the level of a unit product can be beneficial to the development of new products, thereby obtaining additional benefits. The source of funds for reconstruction is reliable.
(3) Choosing a machine tool changer This is a very critical issue. If you choose well, you can successfully complete the transformation task and achieve the change.
Creating goals; poor choice is not only a failure of machine tool transformation, but also a waste of money and time, affecting production. Users can choose carefully according to the conditions that the machine tool transformation should be discussed later.
2. Technical solution preparation
(1) Mechanical and hydraulic system As the end user of the machine tool, the factory must first confirm the condition of the machine tool and hydraulic system. Such as: the current precision of the machine tool, the condition of the mechanical transmission chain, the condition of the lead screw and the guide rail, whether there are major faults, etc., to determine that the machine tool is overhauled and repaired. If it is a non-CNC machine tool to be changed to a CNC machine tool, first consider the feasibility of mechanical modification, the most important is the form of the rail and the installation of the ball screw. Then there is the transmission gap and transmission stiffness of the mechanical transmission mechanism in line with the requirements of CNC machine tools.
(2) Electrical system When doing the CNC machine tool transformation plan, the user can select the CNC system according to the state of the machine tool and the process requirements. The first is to choose CNC manufacturers. At present, the world's performance and reputation are better: Siemens (Germany), Fanuc (Japan), Mitsubishi (Japan), NUM (France), FAGOR (Spain). On the basis of a detailed understanding of the characteristics of the above-mentioned manufacturers' numerical control system and the performance-price ratio, the user can select a suitable CNC system together with the engineering company that implements the transformation. Second, the type of the corresponding control system is selected according to the functional requirements of the machine tool, so that it can meet all the functional requirements of the machine tool without raising the standard.
We suggest that in the selection of CNC systems, special attention should be paid: First, try to move closer to the model series of a famous manufacturer. This is beneficial to both maintenance and management, as well as the purchase of spare parts. Never make the company's CNC system into a million-nation card. Second, we must clearly understand the status of maintenance services of selected manufacturers in China, so as to avoid future problems.
After the CNC system is selected, the user decides to replace or not replace the drive system according to the actual condition of the machine. If it is not replaced, it must be confirmed whether the old drive system and the CNC system can be matched.
For the machine tool measurement system, the current CNC system requirements are incremental pulse code input, so the measurement components such as the inductive synchronous ruler or the resolver used in the old machine tool need to be replaced by incremental pulse encoders and grating scales.
For the peripheral circuit, there are two options for the transformation: "interface type modification", that is, the peripheral relay circuit is reserved, and only the NC and PLC are modified. The new PLC does not participate in the peripheral circuit control, and only processes the command signals required by the NC. The design and commissioning of this scheme is small. The other is "complete transformation". In the case that the relay logic is more complicated, the failure rate is higher, and the user can provide a clear logic diagram, the PLC can be completely modified by the PLC carried by the new NC, simplifying the peripheral circuit, and Rational use of the control capabilities of the PLC. This solution can greatly simplify the hardware circuit and greatly improve the reliability, but the design and debugging work is large.
(3) Determination of the installation form of each part First, the installation of the control system is commonly used in hanging type, cabinet type, desktop type and the like. The selection of the installation method directly determines the wiring mode and cable length of various connecting cables, and also relates to the convenience of operation and maintenance. Second, the installation of the drive system, in principle, can only be installed in the electrical cabinet. The factors to be considered are ventilation cooling, cable routing and length, interference with other electrical appliances, etc. Third, the installation of the motor, according to the actual machine, determine the installation of the motor: 1 flange type, 2 base type, 3 with base flange type, plus the direction of the shaft extension, the position of the motor junction box, etc. The ordering auxiliary parameters of the motor are determined. Fourth, the installation of the measurement system, such as the choice of the structure of the motor built-in encoder, the motor is installed to determine, it is also determined; the external type requires the need for flexible couplings, mounting clips, cable routing direction and length considerations For the grating scale, the installation problem should be taken seriously. In addition to the installation feasibility, the installation fit of the fixed length and the movable ruler, the installation accuracy, and the temperature influence must be considered.
Third, the implementation of the project
1. Selection of construction team
The design of the large-scale modification of the machine tool is good or bad, and the advantages and disadvantages caused by the large modification, in addition to economic factors, rely heavily on the quality of the construction team. This is a very important task. Companies involved in project construction should have the following conditions.
(1) Complete and efficient technical support system The key is the human factor. The company should have a team of engineers, including mechanical, electrical, hydraulic, and process tooling, with many years of experience in design, manufacturing, assembly, and commissioning. At the same time, there should be an on-site construction team that can fight hard. This mode of work is a popular mode under the economic conditions of today's market.
(2) Adaptation to the business management model under the conditions of market economy The key is human factors. Abandoning all the organizational forms and management methods in enterprise management under the condition of planned economy, and building an enterprise structure that can respond quickly to market demand, and continuously improve and perfect in the development of market economy, The company's size, funding status and many other factors.
2. Hardware order
After comprehensive consideration as above, the construction team has been selected, the details of the technical plan are determined, and the order list can be listed. Users and engineering companies can comprehensively consider the two aspects of cost reduction and reliability assurance in a mutual trust attitude, determine the domestic and international order list, and sign a formal transformation contract. At the same time as the order is made, the engineers can start to carry out the system mechanical
Repair, repair and electrical software preparation, laboratory debugging work.
3. On-site debugging
This is the key link for the success of the transformation. At this stage, the engineers complete the machine and power adjustment, the final debugging of the CNC system, the optimization of the parameters of the drive system, and preparation for acceptance.
4. Trial processing acceptance
There are usually two contents: test cutting of standard samples. According to international standards, different types of machine tools have corresponding standard test cutting procedures; the accuracy of machine tools is verified according to the level of measurement of each factory. The user can use the laser interferometer to make measurements, so that the compensation of the machine position measurement system can use the obtained data, thereby improving the accuracy of the machine.
5. Information, training and warranty
After the acceptance work is completed, technical data needs to be organized, archived and provided to the users, as well as technical training and warranty work for the users.
The numerical control transformation of old machine tools is in the ascendant. Under the current situation in China, a large number of faulty machine tools, especially a large number of imported CNC machine tools, precision machine tools and used equipment will be transformed and upgraded, and these equipments will be economically developed as soon as possible with less investment. Performance and efficiency are indeed a topic that many companies cannot ignore.
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