Of course, there are also some engine factories that use a simpler compensation mode. For example, in a cylinder production line with a large production volume, the cylinder bore is precisely "mandatory compensation". The specific method is: every 10 holes are processed by the fine boring blade. The tool wear amount is automatically compensated by 1 μm.
The fine compensation system introduced above is a kind of feedback automatic compensation of closed-loop control, but in fact, in the automotive, diesel engine and other industries, when it is really used in the cylinder hole precision process, there is a manual adjustment/compensation mode, and this situation exists not only The engine factory built in the early days of China has still been applied in some enterprises. Built in the late 1980s, Shanghai Volkswagen Engine No. 1 is one of the first modern automobile engine factories in China. Its cylinder production line is a rigid automatic line composed entirely of combined/special machine tools. Manual compensation. A cylinder “rigid†production line at Chery Automobile Engine Plant 1 uses a similar approach in cylinder bore machining. However, this is not just a process choice in the early stage of the enterprise. The well-known private enterprise Geely Automobile Company has fine compensation functions in the cylinder hole boring process of the three cylinder production lines built in recent years, but all are “open loopâ€. Manual control. However, even if they are all "manual" controls, there are differences in specific practices. In the cylinder line of the Shanghai Volkswagen Engine Plant No. 1, the drive unit c is actually reduced compared to the system composition shown in FIG. In the automatic line, the random detection instrument and the control unit for the full inspection can still automatically give the compensation amount according to the preset compensation requirements, but only need manual operation (generally executed on the machine control panel). The model of Geely Automobile is much simpler. There is no random inspection station in the production line. The operator only determines the compensation and compensation amount according to the measurement results obtained in each sampling period based on the inspection tool set outside the line. The specific method is to first establish a warning (control) area within the tolerance range. When the measured value (or average value) of one (or 3-5 pieces) sampled after a cycle (such as 1 hour) is found to exceed the warning line, Manually perform the compensation operation and adjust to the middle of the tolerance.
2 Cylinder hole fine craft selection
In cylinder machining, cylinder bore precision is one of the most important processes, and the dimensional accuracy and shape error involved will directly affect the quality of the engine. Therefore, the company will take a very cautious attitude in planning this process, not only to ensure the physical quality of the parts and the quality of the process, but also to combine the best situation with the actual situation of the products and enterprises. The process selection of the cylinder bore is involved in processing equipment, boring process, boring tool (including blade material, with compensation function, etc.) and many other factors.
In the environment of the increasingly fierce market competition in the automotive industry, enterprises have accelerated the pace of product upgrading, paying more attention to cost reduction and efficiency, and strengthening flexible production methods. Indeed, since the mid-1990s, machining centers have become more and more popular, and automatic lines (including cylinder lines) consisting entirely of machining centers have emerged. But is this a development trend? It turns out that this is just a desirable model. In recent years, internationally renowned machine tool suppliers and automobile enterprise groups are very optimistic and will give priority to the "hybrid flexible automatic line". This is a flexible automatic line that combines a combination/special machine tool and a machining center. It has the advantages of high production efficiency and considerable flexibility. It can adapt to mass production and production of variants, while the investment is relatively small (by parts). The structural characteristics and process analysis are determined). When the cylinder is machined in this mode, the boring process of the cylinder bore is carried out by a dedicated machine tool. The fine automatic compensation that has been configured and used many years ago further improves the quality of the cylinder bore. However, although the effectiveness of this measure has been confirmed, as a process option, enterprises will still consider economics, applicability and other aspects in planning and implementation, and finally make decisions based on their actual conditions.
Through the investigation of more than 60 cylinder production lines of more than 20 domestic automobile engine factories (including diesel engine factories), we have a clear understanding of the process technology used in the cylinder bore precision. Among the more than 60 cylinder lines, nearly half (47.5%) of the new lines were completed and put into operation after 2002, but in these lines, the proportion of the cylinder hole boring process using the machining center increased to 45%. It shows that the application of flexible automatic lines composed of machining centers in recent years in the manufacture of main parts of engines is expanding.
However, relatively speaking, the above-mentioned "hybrid flexible automatic line" is still slightly superior. According to this manufacturing method, the cylinder hole boring process is completed on a special plane. In fact, many advanced and representative cylinder lines built in China after 2005, such as Dongfeng Cummins, Shanghai GM L850 project, Volkswagen Powertrain (Shanghai), Dalian Diesel Engine Factory, Volkswagen FAW Engine (Dalian) Etc., this mode is adopted.
As for the equipment with automatic compensation of cylinder bore precision, it accounts for 54% of all the more than 60 production lines surveyed. Among them, when the cylinder bore is processed by special plane, 64% of this function is used; Only 25% of the processes in the center process have this function.
In fact, although fine automatic compensation is a mature technology that has been applied for many years (also referred to as “automatic compensation†in the past), with the continuous development of related technologies such as numerical control and detection, especially at the core of the compensation system. The improvement and improvement of the fine-tunable mast, the performance of compensation has been greatly improved and expanded, fully reflecting the continuous improvement of this mature technology.
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