Comment on the development of automobile manufacturing equipment in China

Developing automotive manufacturing equipment has great strategic significance

China's auto industry accounts for about half of the output value and profits of the equipment manufacturing industry. Domestic and international experience has repeatedly proved that the development of the automotive industry depends not only on the technological progress of the machine tool industry, but also on the development of the machine tool industry.

In the past ten years, China's automobile industry has become the mainstay of machine tool consumption, and it consumes about 40% of the machine tools of the whole society. At the same time, more than half of the investment in the automotive industry is used to purchase machine tools, of which imported machine tools account for about 80%. This is the main reason for the rapid growth of China's machine tool consumption and imports. Figure 1 shows that China's automobile production is in sync with the growth of machine tool imports. From a historical perspective, the development of automotive products must be accompanied by the development of manufacturing equipment, and vice versa. For example, for about a century, the automated line of machine tools has dominated the production of the automotive industry with high efficiency. As competition intensifies, the cycle of auto product replacement has been shortened from a few decades to four years, and the automatic line of combined machine tools cannot be adapted due to lack of flexibility. In the 1980s, American auto giant Ford and the machine tool giant INGERSOLL collaborated to develop a high-speed machining center with high flexibility and high efficiency. The advent of a flexible automatic production line accelerated the upgrading of automotive products and improved Business efficiency and flexibility. This is one of the reasons why we can see dozens of new cars coming out every year.

On the one hand, the level and quality of a car depends on the level of equipment; on the other hand, the international competitiveness of a country's automotive industry and an automobile company depends on the advancement of equipment and manufacturing costs. It is the adoption of a large number of advanced numerical control equipments in recent years that has enabled China's sedans to enter the era of flexibility as a whole, and has supported the continuous development of China's automobile industry.

China's automobile manufacturing equipment market is huge

China will be the world's largest market and largest producer of automobiles. According to the overall development strategy, in 2020, China's automobile production reached 14 to 18 million vehicles, ranking first in the world and moving towards the world's automobile industry. One of its signs is that it has advanced manufacturing technology and advanced manufacturing equipment.

At the same time, all automobile companies, especially component companies, must constantly improve their manufacturing technology and equipment in order to survive in the fierce market competition. It can be asserted that in the long period of industrialization in China, the automobile industry will always be the mainstay of machine tool consumption.

China's automobile manufacturing equipment is polarized and generally backward. It is said that "modern weapons and "three-eight" rifles coexist. "On the one hand, there are demonstration factories such as Shanghai GM that use the world's most advanced agile flexible production line; on the other hand, some state-owned old enterprises, such as Jinan The truck company's CNC machine ratio is only 1% (investigation in 2002).

In general, the automobile equipment of joint venture car companies and some private enterprises (such as Vientiane Group) entered the era of flexibility as a whole, reaching the level of the 1990s. Another part of the auto parts manufacturing company still mainly uses ordinary (non-CNC) machine tools, resulting in low quality and can only produce low-end auto parts.

The composition of modern automobile manufacturing equipment and import hotspots

Automobile manufacturing equipment is divided into two categories: vehicle manufacturing equipment and component manufacturing equipment.

● "Four major process equipment" for vehicle manufacturing - vehicle assembly line, body welding and assembly production line, spraying production line, and stamping production line.

Stamping production line: According to statistics, in more than 2,000 parts of the car, stamping parts account for more than 40%. Including body panels, body structural parts and small and medium-sized stampings. At present, China's car production mainly uses automatic and semi-automatic stamping production lines. The next generation is a flexible stamping automatic line. The stamping production line is the only major category of automotive equipment dominated by national products. However, there is a big gap between us and foreign countries in advanced stamping technology.

Car welding assembly lines are almost entirely imported.

The automatic welding line of the car body, the automatic assembly line of the whole vehicle is one of the weakest links of China's automobile equipment.

Currently, automated assembly lines are moving toward flexible and "zero defect" assembly lines. Flexibility is achieved by a large number of welding and assembly robots.

Spraying production line: mainly including painting robot, electrophoresis, drying, gluing and conveying equipment. Due to the lack of domestic technology to integrate process systems, logistics systems and information systems into production lines, it also relies on imports.

●Parts manufacturing equipment:

1 Metal cutting machine production line.

A metal cutting machine production line for the manufacture of car parts, about 70-80% of the amount depends on imports. However, in recent years, with the international famous machine tool manufacturers shifting production to China, and domestic machine tool companies to acquire internationally renowned machine tool manufacturers, the import ratio is declining. The metal cutting machine production line for manufacturing truck parts is mainly based on national products.

Here are several hot metal cutting machines:

1) Flexible production line - FTL. It consists of a high-speed machining center (see later). Mainly used in engine manufacturing. From the end of the twentieth century to the present, according to incomplete statistics, about 100 articles have been installed or will be installed in China, with a unit price of about 20 million US dollars. Among them, imports account for about 90%. Mainly from Germany, Japan, Italy, the United States.

2) Multi-spindle double turret multi-axis CNC turning and milling center / flexible manufacturing unit. With C, Y axis and power cutter head. Equipped with automatic loading and unloading device (including robot) and integrated with material storage and transfer and its automatic control to form a flexible manufacturing unit (FMC). Since such equipment meets the need for one-on-one machining of shaft-type automotive parts, in the past few years, hundreds to thousands have been put into production, of which imports account for about 90%. Mainly from Japan, South Korea, Taiwan Province of China, etc.

It is also important to point out that modern auto parts are increasingly using the car-based grinding process, which requires CNC lathes for powerful turning.

3) Various CNC grinding machines and special CNC grinding machines. Such as: high-efficiency, high-precision centerless grinding machine, equipped with automatic loading and unloading device (including robot), composed of grinding unit; high-efficiency, high-precision crankshaft and camshaft CNC grinding machine, cross-axis special CNC grinding machine, etc., almost all rely on imports. Mainly from Germany, Italy, Switzerland, Japan.

4) Mold processing 5-axis high-speed bed type / gantry type milling machine (machining center). The main features of this type of machine are high speed and good rigidity. Among them, the gantry machining center has a 5-face function for expanding the process performance, and is equipped with a head change mechanism to meet the requirements of different milling speeds of the milling, boring and drilling processes. All rely on imports, and more than hundreds have been put into production. Mainly from Germany, Switzerland, Japan, Italy.

2 Precision forging: close to net forming. Forgings have been applied to the important parts of the car. The precision forging machine has a huge domestic gap and is dependent on imports.

1) Hot precision forging production line or manufacturing unit: German BLM company's hot precision forging gear has reached DIN6 grade, saving 20-30% of materials and improving mechanical performance by 15-30%.

2) Cold precision forging (cold extrusion) production line or manufacturing unit: The United States produces more than 1 million cold extrusion parts per year, 80% of which are automotive parts.

3) Warm precision forging production line or manufacturing unit: The process features that the material is heated to 700-1000 °C for forging, which has the advantages of hot forging and cold forging. US warm forgings account for about 50% of precision forgings.

4) Die Forging Machine / Manufacturing Unit: Forging blanks for automotive parts are die forgings. Among them, the mold and the loading and unloading device are weak links in China.

5) Powder metallurgy sintering forging equipment: Foreign powder metallurgy sintering forging technology has developed greatly, and the weight precision of powder forged connecting rod can reach 1%.

6) Internal high pressure forming technology: It is a high-tech for manufacturing hollow light body components. The internal high-pressure formed parts are light in weight, high in strength, small in number of parts, and few in welds, and are developing rapidly in Europe and America.

7) Spinning forming technology and equipment: Spinning forming has the advantages of high processing precision, and can produce variable-strength wheel rims and spokes.

3 casting production line:

Large tonnage die casting machines / manufacturing units (aluminum alloy castings) rely on imports. Among them, the domestic gap of die-casting molds is huge.

Precision casting production lines (cast iron parts) rely on imports. Among them, the key core system mainly uses the products of the Spanish loramendi company.

4 laser processing equipment

Including laser cutting equipment, laser welding equipment. Laser tailor welded blank stamping forming technology is an advanced technology developed internationally. Laser welding of unequal thickness steel plates of different materials into blanks, and then integral stamping. It can reduce the weight of parts, improve the matching quality of the whole vehicle, reduce material consumption and increase productivity. At present, the laser tailor-welded blank forming equipment is also dependent on imports. In addition, the three-dimensional CNC laser cutting of the car body is a recently developed flexible manufacturing technology, replacing the traditional manual cutting + punching die manufacturing method. Reduce the production preparation cycle from 2.5 months to 5 days.

5 CNC tool system

The CNC tool system for manufacturing car parts mainly relies on imports. Modern car parts and mold processing has been speeding up. High demands are placed on the tool. Solid carbide tools, carbide coated tools (including chemical coating CVD, physical coating PVD), ceramic tools, CBN tools, polycrystalline diamond (PCD) tools, sintered laminated tools.

At the same time, high-speed cutting tool monitoring tools, tool system connection tools, high-speed rotary tool system dynamic balance technology equipment, etc. also put forward high requirements.

It should be pointed out that the modern car parts processing line uses "Smart Tools" - a series of special high-efficiency tools designed for the machining of specific parts. At the same time, the internationally renowned CNC tool supplier also offers "holistic solutions" for high-speed cutting package software packages and tool use (replacement, regrind) services.

The road to localization of China's automobile manufacturing equipment is long

In the 1980s, China's automobile industry shifted its focus to producing cars, and the domestic machine tool industry was not suitable. The localization rate of car equipment has only been 20% for a long time. However, there are still some bright spots, such as automobile stamping production lines, CNC gear processing machines and other national products have a high share. Dalian and Shenyang Machine Tool Group have also provided flexible production lines composed of high-speed machining centers for automobile companies in recent years. Taiwan-made CNC machine tools are used in automobile companies.

But overall, there is still a big gap between China's machine tool products and the world's advanced level:

The gap of independent innovation: The author visited 20 famous machine tool manufacturers mainly providing automobile equipment in Europe and Japan last year. It has been found that in the high-end machine tools such as modern engine manufacturing technology, high-speed machining centers, and manufacturing units composed of advanced composite machine tools, the gap between us and foreign technology development has widened. The important reason is that we basically do not have a system of independent innovation in manufacturing technology. At the same time, the human and financial resources for manufacturing technology research and development are still wide.

At the same time, modern car equipment places special emphasis on "solutions." At present, the sales behavior of the world's leading machine tool companies has completed the revolution from selling equipment to providing "solutions - SOLUTION". This requires the application engineer to be a composite skill-based senior "grey-collar talent." This is a new and more serious gap between us and the international community.

Machine tool performance gap: The main CNC machine tools can not meet the needs of modern cars for accuracy, precision retention, reliability and longevity. For example, the international processing precision has increased by 50 times from 1950 to 2000, and the gap between the accuracy of domestic processing centers and the international advanced level is roughly 15 years;

Software gap: including production line control systems, integration technology gaps, etc. Lack of technology to integrate process systems, logistics systems, and information systems into manufacturing units or production lines.

Analysis of mechanical processing technology and equipment characteristics of car parts

●Flower production line

Although it has undergone revolution for more than a century, it has always been the mainstay of the production of automobiles and parts.

The basic technology of the production line is integrated technology – integrating the process system, logistics system and information system into a production line.

1 Process system: machine tool - tool - workpiece system.

The technological equipment of the modern car water production line has entered the era of flexibility, consisting of CNC machine tools and intelligent tools.

The main requirements for machine tools are: high speed, high precision, high precision retention - high machine tool engineering capability index (Cm / Cmk value), high reliability and so on.

High-speed machining center for engine production line: fast-moving speed 60-100 m/min, acceleration 0.6-1.5g; maximum spindle speed 8,000~15,000 r/min; positioning accuracy/repetitive positioning accuracy——Working table below 1m, 8μm/ 4μm (VDI standard), workbench 1m or more, 10μm/5μm/M (VDI standard).

At present, the latest development of such machining centers in the world is that the main motion generally uses electric spindles, and the feed motion is increasingly using linear motors. At the same time, the three-coordinate modularization and the box-in-box structure are widely used, the machine tool is very simple, the proportion of purchased parts (parts) increases, and the delivery time is greatly shortened. Japan's MAZAK company's latest generation of UH "slimming" type machining center, using double X-axis feed mode, the machine width is shortened by 38 to 57%, greatly reducing the production line footprint and investment.

3 to 5 axis bed type, gantry type CNC / profiling high speed milling machine (machining center) for mold processing: maximum spindle speed 20,000 ~ 40,000 r / min;

The machine tool engineering capability index/process capability index Cmk/Cpk value is /2.0/1.67.

The MTBF of the mean time between failures, the data target of Japan's Yuanzhou in 2002 was 5,000 hours.

2 Logistics system: consists of raw material processing, storage, loading and unloading device, and workpiece transfer device between machine tools.

A flexible manufacturing unit (FMC) is constructed under the condition that a single CNC machine is equipped with a workpiece library or a raw material library and an automatic loading and unloading device (including a robot and a robot), that is, under the condition of integration with material storage and transfer and automatic control thereof. A flexible manufacturing system (FMS) is constructed under the condition that multiple CNC machine tools are equipped with automatic loading and unloading, material storage and transfer, and computer integration with production scheduling. A flexible production line is formed when there is no planned scheduling system and the workpiece flows in one direction.

3 Information System:

It mainly includes production line control, tool change, tooling and attachment replacement, workpiece scheduling, automatic programming, automatic monitoring, automatic compensation, automatic detection of workpiece quality, automatic replacement of tools after wear or damage, and automatic alarm. The latest requirements are CAD/CAM functionality, remote line management and maintenance, troubleshooting and automatic repair capabilities.

The production line is also a model of the combination of manufacturing technology and management technology. In the twentieth century, several major management technologies that affected human manufacturing were mostly produced in automobile production lines. For example, Ford production methods, Toyota production methods, just-in-time (JIT), lean production, etc. It will not be elaborated here.

●The development and transformation of engine manufacturing technology

Just as an engine is the heart of a car, engine manufacturing technology is a concentrated expression of automotive manufacturing technology.

1 Engine manufacturing technology has experienced two revolutions since the car was introduced

The first revolution occurred in the early twentieth century, and Ford Motor Company founder Ford invented a large number of production lines.