Development of new materials and new technologies for green machine tool design

The meaning of green machine design

As a pillar industry of the national economy, the manufacturing industry has created rich material wealth for the society, but it consumes a lot of resources and causes environmental pollution. At present, environmental issues have increasingly become a key factor affecting social and economic development. Environmental regulations formulated by governments are becoming more and more strict, and consumers are also paying great attention to environmental management. Therefore, how to reduce resource consumption and environmental pollution is a major problem facing the manufacturing industry in the 21st century. To this end, it is imperative to implement green manufacturing technologies in the manufacturing industry and implement sustainable development strategies. The mechanical manufacturing industry plays an important role in China's energy conservation and emission reduction work. Metal cutting machine tools are machines for manufacturing machines. They are industrial mother machines. The working hours of general machine tools are more than three or forty years. They are long-life products. In the life cycle, it consumes energy and produces solid, liquid and gas waste, causing direct or indirect pollution to the working environment and the natural environment [1]. Therefore, new energy-saving and environmentally friendly machine tools have become the current research. Hot spot.

New materials for green machine design

With the continuous improvement of material performance requirements of modern engineering technology and science and technology, the research and application of new materials have been rapidly developed. New materials represented by composite materials have been widely used in various fields of the national economy. In the machinery industry, the emergence and application of new materials has led to major changes in some traditional processing techniques. The development of high-tech industries such as modern aerospace industry has increasingly increased the requirements for the performance, precision and processing capability of CNC machine tools and equipment, which has driven and promoted the development of CNC machine tools and equipment manufacturing.

Due to the high temperature resistance, high strength, difficult processing, many alloy materials and composite materials, many complicated structural parts and high process requirements, the aerospace industry product parts require large-scale (heavy-duty, super-heavy), high-speed, precision The trend of compound and intelligent development. How to give full play to the advantages of new material process performance, and apply it to practice, has become an important topic in the field of machine tool design in the new era.

The application of new materials such as carbon fiber, ceramics and composite materials in the machine tool structure makes the machine tool structure lighter and more environmentally friendly, and promotes the development of machine tool processing equipment in the direction of high speed, precision, compound and intelligence. For example, if the large-size support of the machine tool uses artificial granite or fills the concrete in the frame welded by the steel plate, it can save metal resources, increase vibration resistance and thermal stability, and have some complicated parts and components. The use of new materials such as carbon fiber not only makes the machine structure lightweight, but also can improve the life; for some high-hardness wear parts, the use of ceramics and other materials instead of high-hardness steel can reduce weight and save precious metals. The resource can also save the time-consuming and energy-consuming heat treatment process that the high-hardness steel needs to be carried out many times during the processing.

For example, in the machine tool industry in Europe and the United States, the new material resin concrete has been greatly developed, especially in the application of high-precision machine tools, resin concrete is gradually replacing the traditional cast iron. Resin concrete is an emerging structural material. It is a mixture of natural ore (different sizes, different sources) and epoxy resin (as a binder). It has great advantages over traditional cast iron. At present, more and more international machine tool manufacturers are beginning to design machine tools using resin concrete, but for the Chinese market, this field is still blank. Compared with traditional cast iron, resin concrete has the following four advantages:

(1) Low energy consumption. Compared to cast iron, resin concrete consumes less energy and saves about 30% of energy consumption during the manufacturing process. In the face of energy shortages such as electricity, natural gas, and coal, the use of environmentally friendly materials such as resin concrete that are inexpensive and recyclable is the ideal choice. Resin concrete waste and old beds can be used as building materials.

(2) Good vibration absorption. Today, precision CNC machine tools are gaining more and more attention, and workpieces and machine components move faster and faster during high-speed cutting. Increasing the speed, feed rate and component weight will create vibrations that reduce accuracy. Resin concrete eliminates vibration and improves machine tool accuracy.

(3) Highly integrated. The casting temperature of ±45 ° C for resin coagulation is another advantage compared to cast iron at a casting temperature of 900 ° C. The traditional method is to install other parts after the bed is cast. Now it is possible to cast parts directly into the casting, such as pipes, cables, sensors, actuators and liquid chambers.

(4) High precision. The traditional way of making a bed is to install a linear guide after milling and grinding. Because the precision of the conventional casting after demolding is low, the resin concrete after demolding can achieve higher precision. In addition, a higher level of precision can be achieved by recasting.

New technology for green machine design

With the rapid development of science and technology, more and more new technologies are applied to the design field of machine tool products. Green machine tools offer a new concept: to reduce the quality of machine tools, save materials, and reduce energy consumption when using machine tools. At the same time, the modular design is gradually adopted in the design of machine tools to meet the needs of different users, and it is easy to repair, disassemble and recycle products, so that resources can be utilized to the maximum extent and resources can be saved.

1 In the structural design, the weight is reduced, the structure is simplified, and the function is optimized. When designing the machine tool, most of them use the analog design method to change or improve the original product. As long as the original product does not have problems, some structures and dimensions are copied. Come over, or scale up, to do this to create a margin of structural size. Therefore, the space for optimization of the machine tool structure is very large, and the energy saving amount is considerable in the life cycle of the machine tool for several decades.

When designing the overall structure of the machine tool, the principle of simplification of the structure is adopted to simplify the design as much as possible and reduce the number of unnecessary parts. Because behind each part, there is a complete design process, the production process from preparation of the blank to the inspection of the product, all management processes, and the adjustment process during installation. By reducing one part, you can reduce this whole process and reduce manufacturing costs. When designing the drive system of the machine tool, shortening the drive chain as much as possible can not only reduce the number of parts, reduce the loss of no-load power, but also improve the transmission accuracy. In the part design process, the principle of the simplification of the structure is also adopted. After the design of the basic parts of the machine tool is completed, the finite element structure analysis is carried out. Under the premise of satisfying the rigidity, the optimization is improved, the certain dimensions are reduced, the machine weight is minimized, and the material is saved. Figure 1 is a legend of the finite element analysis of the basic part of the machine tool. Structural optimization of some moving parts not only saves material, but also reduces weight, reduces dry running power and energy consumption during machine use.

For the large aircraft project of China's aerospace industry, the plates or forgings used for the blanks of beams, frames, ribs and siding of large aircraft are weighing hundreds of kilograms or even tons, so heavy or even super heavy duty is required. CNC machining equipment such as multi-coordinate, high-speed, high-rigidity, high-power CNC milling machine and vertical machining center. Simplify the structure, optimize functions and reduce weight during machine design, which can save a lot of materials and achieve good social and economic benefits.

2 Adopting new environmental protection technologies, effectively utilizing energy and protecting the ecological environment In the process of designing new products of machine tools, it emphasizes the effective use of resources and energy and the protection of the ecological environment, minimizing the consumption of non-renewable resources and saving raw materials. In practice, it mainly controls noise pollution, exhaust gas pollution, cutting fluid pollution, lubricant pollution and the use of harmful substances. In response to the above requirements, there are many new environmentally friendly technologies that are used in the design of machine tool products.

For example, the lubricating coolant used in the machine tool is a harmful emission, especially the emulsion used in grinding is very harmful to the environment and workers. Now, there are dry and minimally lubricated (MinimizedQuantity Lubricaion, MQL) technologies. Improve the performance of the tool, do not use coolant, or use a special device to provide aerosol or low temperature air (cold air) to solve the problem of cutting fluid contamination. Figure 2 is a schematic diagram of a micro-lubrication technique.

At the same time, in the design of machine tool lubrication system, centralized lubrication or self-lubrication method can effectively reduce the loss and discharge of lubricating oil and reduce the pollution of lubricating oil to the environment. In the modern aerospace industry, magnesium alloys are widely used because of their low density and high specific strength, which can achieve weight reduction. Magnesium alloys are used in aircraft to manufacture siding, ribs, wheel hubs, motor casings, etc. In the aerospace industry, magnesium alloys are used in the manufacture of rockets, satellites and other components. Magnesium alloy powder is easy to generate hydrogen when it is in contact with water. Hydrogen is easy to burn and has explosive properties. Therefore, the processing of magnesium alloy is particularly high-feeding, high-speed cutting, and can not be flushed and discharged. Only mineral oil can be used, and the cost is high. Magnesium alloy has the characteristics of no need of grinding and polishing, fast heat dissipation, and good surface quality without cutting fluid. Therefore, the emergence of environmental protection technologies such as dry cutting and micro-lubrication solves the problem of processing magnesium alloy materials in the aerospace industry. Reduced processing costs.

Modular design for easy reorganization and green remanufacturing

In the new product design of the machine tool, the modular design can meet the needs of different users, and it is easy to repair, disassemble and recycle the products, so that the resources can be utilized to the maximum extent and resources can be saved. Combined machine tools are a good example of modular design and ease of recycling. The combined machine tool is a high-efficiency special machine consisting of a large number of general-purpose parts and a small number of special-purpose parts. When the product or process changes, the original machine is disassembled, and a large number of general-purpose parts can be reused to the new machine. On the basis of the existing standards, if the corresponding standard can be set for the main component sizes of some general-purpose machine tools, it will be beneficial to the recovery, modification or reorganization of the machine tool, which greatly saves the machine tool and causes the original [2]. Figure 3 and Figure 4 respectively It is a modular design drawing for turning products and boring and milling products.

Conclusion

With the continuous deepening of research on new materials and new technologies, the continuous development of new machine tools that save energy and green ecology has been greatly promoted. China is a big manufacturing country, improving the independent innovation capability of the industry, applying new materials and new technologies to develop green machine tools, realizing the recycling of resources, and realizing the overall optimization of economic and social benefits of enterprises. It has important strategic significance for revitalizing China's machine tool industry. Social energy conservation and emission reduction have a major impetus.