New Trends In Automotive Engine Manufacturing Industry
時間：2020/10/5 關(guān)鍵詞：YongPu Precision 瀏覽量：14211
Since entering the 21st century, the engine manufacturing industry has undergone a series of changes in terms of products, manufacturing processes, tools, and production management, many of which are different from the past engine manufacturing enterprises.
The trend towards light weighting is more obvious in terms of products, with aluminum alloy replacing cast iron for cylinder block parts. The cylinder head products are simplified, and the previous overhead camshaft form is not adopted, making it easier to process the cylinder head. In terms of process, continuous optimization has been made, and the crankshaft has developed a new high-speed external milling process in addition to the "turn-turn-pull" technology, making it more flexible. The camshaft adopts a set-in type, rather than an integral type, which makes the processing simple and flexible. The expansion and cutting process of the connecting rod is increasingly used by enterprises, and it is becoming more mature.
High-speedization is also quite obvious in engine enterprises, with a large number of coated hard alloy tools PCD and CBN, and the cutting speed has greatly increased. HSK chucks are also relatively common. The use of composite processing processes and tools is also quite common to save equipment investment and reduce processing time. For example, a multi-functional tool that can complete drilling, milling, and threading in one go is used. In short, on the product side, it is possible to obtain satisfactory performance while keeping the processing process simple, and to solve some of the processing problems in the casting, so that there is less machining allowance during mechanical processing.
In terms of process technology, new processes are adopted to meet the needs of high-speed and flexibility. There are also many differences in production organization and management. The structure of the enterprise is simple, and many service departments, such as oil, cutting fluid, tools, and equipment spare parts, are managed by professional companies. People are motivated through groups and job rotation. Logistics and equipment management are also key areas, and TPM is an important part of engine manufacturing enterprises. In terms of quality, German enterprises place great importance on process quality.
Product aspects
(1) Lightweighting research shows that if the mass of a car can be reduced by 10%, its fuel economy can be improved by 3% to 4%, and the emission of the car will also be reduced. To this end, car manufacturers in various countries want to make the engine lightweight, high-speed, high-power, and have higher durability. A good way is to use an aluminum block. Its advantages: ① Aluminum has good thermal conductivity, which can improve the compression ratio of the engine and is very beneficial to improving power. ② The expansion rate of the cylinder block and the cylinder head is the same, which reduces thermal stress and improves the rigidity of the cylinder block and cylinder head junction surface at the same time. ③ It is light in weight.
?。?）Cylinder Head Structure The structure of the cylinder head is generally an integrated aluminum cylinder head with the camshaft bearing hole, which is divided into two or three parts for the convenience of process machining. The camshaft is not placed on the cylinder head but is installed inside the cover shell.
?。?）Camshaft The function of the camshaft is to control the opening and closing of the intake and exhaust valves. The first change is that the camshaft for four and five valves is a lightweight hollow camshaft for weight reduction. The second change is that the camshaft blank is generally a casting or forging, which is then roughly machined, heat treated, and finally ground. The new camshaft manufacturing method uses assembled blank parts, where pre-fabricatedcams and related parts are assembled on a steel pipe, welded to fix their axial and angular positions, and increases flexibility, but the disadvantage is the high cost.
（4）Balance軸 In a three-cylinder engine, in order to reduce vibration and make the engine run more smoothly, a balance shaft is added to the product. At present, the 1.2L four-valve engine used by the VW Group for the Polo is equipped with a balance shaft. Since this part can significantly balance the engine vibration and improve the engine operation, in the future, the four-cylinder engine of ZL will be equipped with a balance shaft.
Process Cutting Tools
?。?）Product changes引起 process changes include the aluminum cylinder block, where some foreign factories cast the cylinder block with a surface that has a sawtooth shape, and then pour it. The cast iron part is 2-4mm away from the upper plane, and in order to facilitate the machining of the upper plane of the cylinder block. The rough machining of the cast iron cylinder block is completed in the blank factory, leaving a 1mm allowance. In the process arrangement, the cylinder hole and the main bearing hole are machined later, while the upper and lower planes and the four side faces are machined first. This is different from the previous process arrangement, which makes the machining process simpler than before. The cylinder head becomes a rectangular block, which makes the machining of the cylinder head easier than before. Because there is no need to machine the camshaft bearing hole, it is possible to use a special simple machining center machine tool to achieve high speed and flexible changes. After using the assembled camshaft, the heat treatment and assembly of the cam are carried out by the supplier, and the semi-finished products are provided to the manufacturer. The process is as follows: Main journal grinding - Main journal rough and finish grinding - Cam polishing - Cleaning.
?。?）Three important trends. Foreign engine factories show more obvious trends in three important areas, mainly as follows:
First is the high-speed. High-speed processing can improve productivity and reduce delivery time. To achieve high-speed processing, the main steps are: ①The machine tool should be able to achieve high-speed spindles. ②HSK hydraulic chucks, with high positioning accuracy and good rigidity. ③The use of coated carbide tools, metal ceramics, ceramics, CBN, PCD tools is extensive. For example, on the cylinder head line, a large number of high-speed machining centers are used for hard零件 processing. It can simplify the process method, process links, save costs, and has flexibility. For example, camshaft processing, German diesel engines in Hungary, in the past, the processing of the journal was performed by turning and grinding, now it is changed to CBN tools to complete it at one time, to achieve the required surface roughness, no longer grinding, can reduce a lot of investment. ③Dry processing. The advantage is that it can meet the requirements of environmental protection and reduce the total cost. For example, the rough machining of the cylinder block cylinder hole, using ceramic cutting tools without emulsification. At present, foreign countries attach great importance to the use of spray - quasi-dry processing in dry processing.
(3) Flexibility. The flexibility of the production of the engine manufacturing industry is one of the ways to go. In the traditional automatic line, some of the workstations are replaced by CNC or machining centers to achieve flexible processing. The production line called FTL is used in Japanese factories more often. It is mainly suitable for family products. Strictly speaking, this is still the design concept of the automatic line.
The flexible manufacturing system composed of dedicated machining centers is mainly used in cylinder heads and cylinder blocks. From the perspective of production volume, it can be achieved. From the traditional FMS system, the starting annual production volume is 50,000 pieces/year to the traditional automatic line's annual production volume of 200,000 pieces/year. If we want to plan a fully flexible production line suitable for mass production, to suit the uncertainty of purchasing, due to the continuous renewal and design of new varieties, environmental requirements and production requirements, etc. In the flexible production line, considering these factors can make the investment of more than 500,000 pieces per year more reasonable, and it can save about 10-20 billion US dollars in the next 10 years.
Since the cylinder block needs to be clamped less times, and mostly castings. The material and size determine that the automatic line is more economical. At present, the mixed production line is a new trend. In terms of technology, the large excess amount of cutting is completed on the traditional automatic line, and the processing of the front and rear end faces and sides of the cylinder block is done by the flexible production unit.
（4）High efficiency From the situation of Japanese automobile manufacturing industry, the average improvement of cutting efficiency is 28% every five years, including an average increase of 19% in cutting speed and an average increase of 8% in feed rate, and the improvement of cutting efficiency in recent years is more than 30%. At present, the production cycle of the main parts of the engine has been shortened to 30-40s. It has been shortened by 50% compared with ten or more years ago. For example, in the milling processing of the gray cast iron material cylinder block, the cutting speed can reach 700-1500m/min by using the high-speed machining center machine tool. The tool uses CBN tool blade. (auto1950) In the milling processing of the cylinder block and cylinder head of aluminum alloy material, PCD tools are widely used. Considering that a large centrifugal force will be generated when the tool rotates at high speed, the tool body is made of high-strength aluminum alloy material. The camshaft and crankshaft are ground with CBN grinding wheel at high speed. For the hole processing of the crankshaft and camshaft, in order to improve the efficiency, the hard alloy drill bit with internal cooling is used instead of the past high-speed steel drill bit. Even the thread tapping of the crankshaft adopts the chip-free thread tap. There is a trend that the machining center with high-speed processing has a hot-mounted tool system. In short, there is a clear trend in the engine manufacturing industry to adopt high-speed processing to improve efficiency.
?。?）The expansion and breaking process is widely used Since the expansion and breaking process was used for the cutting of the large head of the connecting rod, most factories have adopted the expansion and breaking process. There are some problems in the application of this technology in domestic factories, mainly the waste rate and the burst of the connecting rod during assembly. However, foreign factories have mastered this process very well. Their waste rate is 0.8%, and the burst of the connecting rod during assembly is almost zero. The problem is the gap control of the support block during expansion and breaking.
?。?）Based on the turning and pulling of the crankshaft, the high-speed external milling is combined in recent years. The processing of the main journal and the connecting rod journal of the crankshaft is generally completed by the turning and pulling process. However, the axis of the connecting rod journal is not on the same center line. For example, for three-cylinder and six-cylinder engines, the processing is a bit troublesome. At present, there is a processing process scheme: the main journal is turned and pulled, and the connecting rod journal is milled by high-speed external milling. In this way, it is better to flex the connecting rod journal.
?。?）The new improvement of the crankshaft balancer is to correct the unbalanced quantity by using the polar coordinate optimization method of high-speed drilling. In the past, high-speed steel was used, and the new method is that the drilling of the crankshaft adopts the overall hard alloy drill bit. There is a cooling fluid hole in the center of the drill bit. This kind of drill bit can perform large feed drilling.
（8）Cylinder hole laser honing. In recent years, surface laser machining honing process is gradually used. In order to achieve the surface roughness and oil storage performance of the cylinder hole at the same time, it is necessary to use special processing technology, that is, laser machining honing can achieve the processing requirements, and at the same time, it will not affect the processing quality of the cylinder hole surface. After using laser honing, the automobile engine can reduce fuel consumption, reduce emissions, and reduce wear. In addition, at present, diesel engines are widely used in cars. Diesel engines are small in volume and large in power. TiC is added to the cylinder block casting. In order to remove the TiC on the surface of the cylinder hole and the burrs generated, and at the same time to achieve the surface oil storage amount, high-pressure liquid honing is developed. The process is: rough honing + fine honing + high-pressure liquid dressing + polishing.
?。?）The camshaft of the crankshaft grinding machine adopts CBN grinding wheel high-speed grinding, which is very common. At present, the processing of the crankshaft is also gradually beginning to use CBN grinding wheel processing. Generally speaking, as long as the lift change, the process route of the four-cylinder crankshaft is still the past better: the main journal is ground by multi-grinding wheel, and the connecting rod journal is ground by double grinding wheel respectively. If you want to process four-cylinder, five-cylinder and six-cylinder crankshafts, you have to use CBN single grinding wheel or double grinding wheel to grind the crankshaft, so that the flexibility is good, and the grinding wheel can process 600-800 pieces each time after each dressing.
Organization and Production Management
（1）Simple structure. Compared with the past, the organizational structure of the engine factory is just a productive factory, especially in overseas factories. The service work is handed over to the professional department. For example, tool management (Tool-Management) was proposed in the American enterprise in the 1990s, and it began in the American General Motors Saturn project 16 years ago. At that time, tool management was mainly logistics, the tool was relatively simple, there was no precision tool, and it gradually improved and developed into a complete system, and even participated in project support at the beginning of the new project. It was promoted in Germany and Europe in the late 1990s. Although it was applied less, it was a potential management mode, and from the scope of application, more and more enterprises, especially the automotive industry, will adopt it. At present, the OPel factory in Hungary, the Volkswagen factory in Poland, and the Shanghai factory of General Motors in the United States are carrying out tool management. It reduces the number of grinding, warehouse management, purchasing, and technical management personnel, so the structure is simple.
?。?）In the increasingly fierce competition in the automotive industry, reducing the cost of products has become an important strategy for car manufacturers to compete. Treating cost reduction as a hard indicator to implement is a trend in the development of the global automotive industry. The engine factory is no exception, and cost reduction is implemented as an important goal. Generally, each workshop establishes a cost center, and the main indicators are work waste, material waste, personnel expenses, tool and auxiliary material expenses, equipment depreciation, etc.
?。?）TPM and Personnel Incentive The equipment of the engine factory is relatively complex, precise, and has a certain technical content. An important task after the completion of the new production line planning is TPM. Firstly, a specific implementation plan is proposed, and each line is specified with a person in charge, and the point inspection and professional point inspection are strengthened. Propose appropriate solutions for specific machine tools. It is not a matter of doing some superficial work, but to execute according to a simple and clear idea, and then to be down-to-earth. Use some suitable personnel instead of highly educated employees, focusing on training on the post. To encourage employees, actively adopt the vacation system, and the annual vacation plan of the whole production line is posted on the production line. Repair, operators, etc. are organized into groups. In order to solve the new problems arising from the monotonous production, job rotation is carried out after a period of time.
?。?）Quality Management Any engine factory will place quality at the core of the company's strategy. Quality management is one of the more important "internal skills" for development. There is no choice but to threaten the survival of the enterprise. Only those companies that are committed to quality improvement can succeed and profit. The key means for the engine factory to improve quality is to determine quality objectives. Adopt zero defects production as the core process, strengthen quality process control. Mobilize all employees to participate, and let the workshop workers solve the problems by themselves, and establish QC groups to improve quality.
