Development status of cutting and cutting tool tec

2022-07-29
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Development status of cutting and tool technology in automotive industry

1 In recent years, China's automobile manufacturing industry has developed very rapidly. Major domestic automobile groups are increasing investment, and many private enterprises have joined the ranks of automobile or its parts manufacturing. Almost all the world's major auto companies and famous auto parts manufacturers have come to China, either in joint ventures or sole proprietorships, and have tried to join the upsurge of manufacturing cars and their parts in China. The workload of machining and metal cutting related to automobile manufacturing, especially the manufacturing of engine, gearbox, transmission shaft, axle and other parts required by automobile, has increased sharply, resulting in the increasing demand for cutting tools closely related to machining and metal cutting, as well as many new requirements. At present, the development of the automobile industry is characterized by intensified competition, further improved requirements for customer satisfaction, timely launch of new products or conversion of new models according to market demand, and increased flexibility of production. When the market has a demand for a certain product, we must seize the opportunity to produce products that can meet the needs of the market. The growth of production may be steep. The cutting tools that are required to support production must also adapt to such requirements and changes, and can be provided in time to ensure that they meet the needs of production in terms of quantity and quality. The quality requirements of automobile parts manufacturing are also constantly improving, whether it is machining accuracy, shape and position requirements or surface quality requirements have been improved. At the same time, in order to meet the requirements of the new product quantity control, it is required to have a good traceability of the produced products, that is, to control the whole process of product manufacturing. When the product is found to have quality problems, it is required to clearly understand the problem in which link, the number of affected products and where it occurs. It is required to have a perfect control and traceability of the important influencing factors in the product manufacturing process, In terms of cutting tools, they must be able to make timely and rapid response to problems on the production site, provide strong and efficient technical support, and control and trace the manufacturing process of cutting tools. In the face of fierce market competition, the automotive industry is fully implementing lean production. At the same time, it is required to continuously reduce the tool cost, and the requirements for tool logistics, inventory, etc. are also increased. At the same time, due to the improvement of standards and requirements for environmental protection, health and occupational health, the automotive industry has more consideration and control on these aspects, and has new and higher requirements for metal cutting and cutting tools. All these require the cutting and cutting tool industry to continuously develop new technologies, new materials, new processes and new management methods to adapt to the emerging new technologies, new materials, new processes and new management systems in the automotive manufacturing process

2. Developing towards flexibility and high-speed machining

in order to adapt to the changing needs of the market, automotive products and their parts are being updated and changed more and more rapidly. In the past, a large number of special machines or rigid automatic lines could not adapt to this rapidly changing market demand because they were not easy to replace and adopted three-dimensional optimal design products or the transformation cost was expensive. Therefore, more and more flexible production lines have been adopted in the production lines of automobile parts processing, or the processing production lines formed by the combination of flexible processing equipment and special machines. Especially in new projects, flexible processing lines are preferred, and a large number of processing centers are used. Parts of different specifications can be produced on one production line to meet the needs of different product production, Moreover, when the product is upgraded, it can be easily converted to a new production line only by changing the processing program and related tools and fixtures, and it is also convenient to adjust and improve the process, increase and reduce the tools. In terms of workshop layout, the floor of the workshop shall be kept as complete as possible. Few trenches have been excavated for centralized cooling. Machine tools and other equipment can be easily installed and moved to new positions as required to form a new production line. For example, in the past few years since the establishment of the plant, Shanghai General Motors Co., Ltd. has moved machine tools many times as required to reduce the equipment of production lines with excess capacity for the production of new projects, or to increase the equipment of production lines with relatively weak capacity, so as to maximize the use of equipment capacity and quickly meet the needs of the market with extremely high flexibility. Accordingly, the cutting tools are required to adapt to this highly flexible production and rapidly changing production output and production varieties. Therefore, the cutting tools for CNC machine tools and machining centers have obtained great market and high-speed development, which has also caused more and more enterprises and research units to continuously invest a lot of human and material resources in the research and development of new cutting technologies and new cutting tools

due to the large production volume, many varieties and fast production pace of automobiles and their parts, although flexible production lines are adopted, the beat requirements still need to be met. Therefore, it is necessary to improve cutting parameters and adopt high-speed cutting. The adoption of machining center equipment also makes it possible to realize flexible and efficient production at the same time. Automobile and its parts manufacturing, especially the manufacturing process of new factories and new projects, is developing in the direction of high-speed machining. More and more CNC high-speed machining centers are used. The spindle speed of many machining centers has reached tens of thousands of revolutions. For example, the tool speed of drilling and boring the bottom hole of air inlet and exhaust duct and seat ring of aluminum cylinder cover is more than 10000 revolutions, and the linear speed can reach about 1500m/min, The linear speed of some surface milling can reach 4000m/min. The tool speed of semi fine boring and fine boring cast iron cylinder block cylinder bore has also reached 300 revolutions, and the linear speed can reach 800m/min. In the machining of 1.6L engine cast iron cylinder block of Shanghai General Motors Co., Ltd., many surface milling linear speeds have reached more than 1000m/min. At the same time, high-performance cutting has also been greatly developed. A considerable amount of allowance is cut off at one time, especially in rough machining. The cutting efficiency is improved and the cutting process is reduced. Semi finishing and finishing are combined in the machining of some stations. Accordingly, many new changes have taken place in cutting tools and cutting technology

3. Superhard tools have been widely used

great changes have taken place in tool materials. Superhard tools such as CBN (cubic boron nitride), PCD (polycrystalline diamond) and ceramic tools have been widely used. Because of its extremely high hardness, PCD tools have a very long service life when machining aluminum workpieces and other non-ferrous metals and their alloys. In recent years, with the extensive application of light materials (such as aluminum alloy, composite materials, plastics, etc.) in the automotive manufacturing industry, the application of PCD tools has also increased significantly. At present, many parts of automobile engine such as cylinder block, cylinder head, gearbox shell, valve body, groove body, side cover, etc. are made of aluminum. PCD tools are widely used in the processing of these parts, which has achieved good results. Generally, the service life of each tool is about thousands of workpieces, up to 15000 to 20000 pieces

cbn blade is characterized by extremely high hardness (second only to diamond), especially its good red hardness. It can still maintain its hardness and good cutting performance at a high temperature of more than 1000 degrees. It meets the needs of high-speed cutting, and also meets the processing needs of some high hardness and difficult to machine parts. It has obtained good application results in the processing of cast iron parts such as engine block and powder metallurgy parts such as valve seat. For example, CBN blades are used in the semi precision boring and precision boring processes for the machining of the cylinder bore of the cylinder block. The cutting speed can reach 800m/min, and the tool life is more than twice that of cemented carbide tools. In the machining of cylinder head joint surface of cylinder block, the cutting linear speed of CBN milling cutter can reach more than 1200m/min, even 2000m/min, and the feed speed can reach 1000 ~ 2000mm/min. At present, in order to reduce the one-time equipment investment, reduce the number of equipment in the production line, and at the same time hope to ensure the production pace, existing auto parts manufacturers have adopted machining centers with high-speed machining capacity to significantly increase the cutting amount, and at the same time, CBN cutters suitable for this kind of high-speed cutting. For example, in the processing of in-line four cylinder engine cylinder block, CBN tools are used for milling almost all surfaces. Although CBN tools are expensive, it is still very economical in general considering the improvement of processing efficiency and the saving of investment cost. In the processing of gearbox shell, Shanghai General Motors Corporation changed a carbide boring cutter to a PCD cutter, and the service life of the cutter was increased from 3000 pieces to 70000 pieces. The economic benefit is very obvious. CBN tools can be used to process hardened workpieces, so turning can be realized instead of grinding. For example, in the processing of gearbox input and output shafts, Daewoo automobile company uses CBN tools to turn the grooves on the shafts, instead of the original grinding with formed grinding wheels

as a new type of cutting tool of high hardness materials, ceramic cutting tool is also a tool that deserves attention and is expanding its application field. The brittleness of ceramic cutting tool is being improved. Now there are toughened ceramic cutting tools, which can be applied to the rough machining of cast iron workpieces, such as the rough machining of cylinder bore of engine cylinder block, Both V-type 6-cylinder engine and in-line 4-cylinder engine use ceramic tools for rough machining of cylinder holes, which significantly improves the machining efficiency. The linear speed of boring and cutting can reach 700 ~ 800m/min

4. With the development of surface engineering and tribology, coating technology has achieved rapid development in recent ten years. The technology and equipment are becoming more and more mature. The application of coating technology on cutting tools is becoming more and more extensive, and the results are obvious. More and more new coatings have been developed. At present, tin, tic, TiCN, TiAlN, zrcn and other coatings are widely used on the cutting tools used in the automotive industry. Good application results have been obtained on drill bits, reamers, gear hobs and taps, and the tool life has been significantly improved. At present, almost 75% of the cemented carbide tools used in the automotive industry are coated. With the improvement of the requirements for tool regrinding, more and more tools need to be recoated after regrinding, which makes the application of coating have a broader prospect. At the same time, how to make the re coated tools after grinding reach the performance level of the original new tools requires greater efforts from the coating manufacturers and coated tool users. As a single coating material is difficult to meet the requirements of improving the comprehensive performance of cutting tools, the coating components will tend to be diversified and composite. In the composite coating, the thickness of each single component coating will become thinner and thinner, and gradually tend to nano. The coating process will be more targeted to meet different cutting requirements. At present, the coating industry is still doing more work to further improve the performance of various coatings, such as combining multi arc process and sputtering process, optimizing the coating structure, developing multi-layer coatings to improve toughness and adhesion, adding other alloy elements such as chromium, zirconium, vanadium, boron, hafnium and silicon to further improve the toughness, hardness, chemical stability and other properties, and striving to develop nano multi-layer coatings. The recent development in coating field is that diamond film is coated on cemented carbide tools by CVD and other methods, so that tools with complex shapes or chip breaking grooves can also have the performance of diamond tools. In addition, soft coatings such as MoS2 are being tried to be applied to cutting tools to improve the lubrication state in the cutting process and improve the performance of metal cutting

5. New tool handle and

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