Experience in improving the reliability of CNC machine tools

At present, most of our manufacturing industries and companies have the largest number of production and processing equipment, and more than half are old machine tools with a service life of more than 10 years. Even CNC machine tools are mostly economical CNC machine tools, and their production equipment and technology are obsolete and backward. The products processed by this kind of equipment are generally poor in quality, have few varieties, have low grades, have high costs, and have a long delivery period. As a result, they lack competitiveness in the international and domestic markets and directly affect the products, markets, benefits, and impacts of an enterprise. The survival and development of the enterprise. Therefore, we must greatly improve the NC rate of the machine tool.

1 The market of CNC machine tools and production line transformation industry The transformation of CNC machine tools The total number of China's machine tools is more than 3.8 million units, of which the total number of CNC machine tools is only 11.34 million units, that is, the numerical control rate of China's machine tools is less than 3%. In the past 10 years, China's CNC The annual output of machine tools is about 0.6-0.8 million units, and the annual production value is about 1.8 billion yuan. The annual production rate of machine tools is 6%, and the annual production value is 12% (the latter two are 31.6% and 75.4% respectively). Moreover, economical CNC machine tools in CNC machine tools account for more than 80%, and there are not many advanced machine tools such as automatic machine tools. More than 60% of China's machine tools have a service life of more than 10 years; less than 20% of automatic and semi-automatic machine tools are under 10 years old, and FMC/FMS and other automated production lines are even more accessible (60% of US and Japanese automatic and semi-automatic machine tools. the above). It can be seen that most of the manufacturing and processing equipment in most of our manufacturing industries and enterprises are traditional machine tools, and more than half of them are older machine tools with a service life of more than 10 years. Even CNC machine tools are mostly economical CNC machine tools, and their production equipment and technology are obsolete and backward. The products processed by this kind of equipment are generally poor in quality, have few varieties, have low grades, have high costs, and have a long delivery period. As a result, they lack competitiveness in the international and domestic markets and directly affect the products, markets, benefits, and impacts of an enterprise. The survival and development of the enterprise. Therefore, we must greatly improve the NC rate of the machine tool.

According to experts' predictions, by the year 2000, the consumption of CNC machine tools in China could reach 24.02 billion yuan. These demands are met on the one hand by purchasing new equipment. On the other hand, if we take full advantage of China's existing stock assets, replacing and reducing the purchase of new equipment with renewed and transformed equipment can have a multiplier effect. Estimated by the demand of 24.02 billion yuan, even if 10% of the demand is realized through the regeneration of equipment, there will be a market of 2.4 billion yuan each year.

The NC transformation market for imported equipment and production lines Since China's reform and opening up, many companies have introduced technology, equipment and production lines from abroad to carry out technological transformation. According to incomplete statistics, from the period of 1979 to 1988, there were 18,446 imported technological transformation projects in the country, totaling approximately US$ 16.58 billion.

Of these projects, most of the projects have played a proper role in China’s economic construction. However, due to various reasons, some imported projects may not be able to operate normally, or even paralyzed, equipment or production lines, which will affect the efficiency of the company and seriously impede the enterprise's difficulties. In order to make full use of these equipment and production lines, we conducted a survey on some technological transformation projects that were introduced more than 10 years ago and related to the machinery industry. We learned that after introducing some equipment and production lines from abroad, some of them were poorly digested and absorbed, and spare parts were incomplete and improperly maintained. As a result, the introduction of equipment and instruments, production lines, and software, processes, and management were neglected. The project is incomplete and the equipment potential cannot be used; some of them cannot even be started and run, and they do not play their due role; some of the product lines of the production line sell well, but they cannot meet the production standards due to equipment failure; some are because of high energy consumption and products. Low pass rates result in losses; some have been introduced for longer periods and require technical updates. For various reasons, some equipment not only did not create wealth, but also consumed wealth.

These equipment and production lines that cannot be used are a burden, and they are a large number of stock assets. Repairing them is wealth. As long as the main technical difficulties are solved and key technical problems are solved, the smallest investment can be used to revitalize the largest stock assets and gain the greatest economic and social benefits. This is also a great transformation of the market.

2 The content, technology and principles of NC transformation The rise of foreign transformation industry In the USA, Japan, Germany, and other developed countries, the machine tool industry is in a sluggish state today. Their machine tool transformation is as a new economic growth industry, and is full of business. Golden age. Due to the continuous advancement of machine tools and technology, machine tool rebuilding is an eternal task. China's machine tool transformation industry has also moved from the old industry to a new industry dominated by numerical control technology. In the United States, Japan, and Germany, the use of numerical control technology to transform machine tools and production lines has a broad market, and a new industry has been formed for the numerical control of machine tools and production lines. In the United States, the machine tool industry is called the Remanufacturing industry. The well-known companies in the recycling industry include Bertsche Engineering, Ayton Machine Tool, Devlieg-Bullavd Service Group, and US Equipment. The American Depot company has opened a company in China. In Japan, the machine tool transformation industry is called the Retrofitting industry. The well-known companies engaged in the conversion industry include Daxie Engineering Group, Gangsan Machinery Corporation, Chiyoda Engineering Machine Company, Nozaki Engineering Corporation, Hamada Engineering Corporation, and Yamamoto Engineering Corporation. The contents of the NC transformation of the CNC machine tool and the production line of the NC content include the following points:

One is to restore the original function, diagnose and recover the faults in the machine tool and production line; the second is NC, add the digital display device on the ordinary machine tool, or add the numerical control system, and transform it into an NC machine tool and a CNC machine tool; Refurbishment, to improve precision, efficiency and automation, to refurbish mechanical and electrical parts, to reconfigure the mechanical parts and restore the original precision; to update the CNC system that does not meet production requirements with the latest CNC; the fourth is technology Renewal or technological innovation, in order to improve performance or grades, or to use new technology, new technology, on the basis of the original to carry out large-scale technological updates or technological innovation, to greatly improve the level and grade of the renovation and transformation.

The criteria for the evaluation of the NC transformation are as follows:

The investment in transformation is within 30% of the price of new machine tools, and can achieve 70% to 80% of the efficiency of use. It is considered successful; the payback period of the reform investment is less than the payback period for the purchase of new machine tools (generally 5 to Less than half of 6 years (usually 2 to 3 years), transformation is valuable.

There are exceptions. For example, if a key equipment of a project is purchased from a foreign country, its delivery time and price are unacceptable. The reform evaluation criteria should be considered separately.

The advantages and disadvantages of the numerical control transformation to reduce the amount of investment, delivery time is shorter than the purchase of new machine tools, generally can save 60% to 80% of the cost, the transformation costs are low. Especially large and special machine tools are particularly noticeable. General large-scale machine tool transformation, only spent 1/3 of the cost of new machine purchase, delivery time is short. However, in some special cases, such as high-speed spindles, automatic tool exchanges, and automatic tray exchanges, the production and installation of the trays are too time-consuming and costly, and often the cost of improvement is increased by 2 to 3 times. Compared with the purchase of new machine tools, it can only save investment 50. %about.

The stable and reliable mechanical properties, structural limitations of the use of bed, column and other basic parts are heavy and strong cast components, rather than the kind of welded components, the modified machine performance, high quality, can continue to be used as new equipment for many years. However, due to the limitations of the original mechanical structure, it is not appropriate to make a breakthrough transformation.

Familiar with understanding the equipment, easy operation and maintenance When purchasing new equipment, it is not known whether the new equipment can meet its processing requirements. Renovation is not the case, and the machine tool's processing capability can be accurately calculated. In addition, due to many years of use, the operator has already understood the characteristics of the machine tool, and the training time is short and effective in operation and maintenance. Once the modified machine is installed, full-load operation can be realized.

The existing conditions can be fully utilized to make full use of existing foundations without having to rebuild the foundations as in the case of new equipment. At the same time, fixtures, software programs, templates, and peripherals can also be reused. Taking a machining center as an example, the cost of process equipment generally accounts for more than 10% of the price of the entire machine tool.

The latest control technology can be used to increase the automation level and efficiency of production equipment in a timely manner in accordance with the development speed of technological innovation, improve the quality and grade of equipment, and change the old machine tool to the current level of machine tools.