Analysis of Quality Status of Main Volumetric Vacuum Pumps in China

Analysis of the Quality of Main Vacuum Pumps in China by Li Chunying (National Vacuum Equipment Quality Supervision and Inspection Center, Shenyang 110042, Liaoning, China) Analysis, expounding the quality improvement of volumetric vacuum pumps in recent years and the main problems that still exist and the causes of the problems. Improvement measures and analysis of common problems common to vacuum pumps have been made.

China's production of vacuum-acquiring equipment began in the 1930s. In 2001, it produced an annual total of about 120,000 vacuum-produced equipment. After nearly 70 years of development, China has a complete range of vacuum equipment, and the quality of water is steadily increasing. It basically meets the needs of the domestic market but faces the international market after China's accession to the WTO. The level of quality of vacuum-acquired products is still very high. The gap is awaiting us to think calmly and study countermeasures in an effort to catch up with the international advanced level in the shortest possible time.

The volumetric vacuum pump with a large amount of vacuum is widely used in vacuum equipment to do a specific quality analysis.

1 Rotary vane pump Rotary vane pump is the largest in all vacuum equipments and the most commonly used vacuum pump. The annual output of the pump is about 100,000 sets. Large-scale rotary vane pump and other vacuum pumps form a vacuum unit, widely used in chemical, machinery, metallurgy, food, construction forestry electronics, national defense and other fields; small pumps are mainly used in the production of rotary vane pumps in food, medical and medical appliances, packaging and other industries. There are nearly one hundred enterprises, such as through the test in 2001: SDIC Nanguang Co., Ltd., Zibo Vacuum Equipment Factory Co., Ltd., Beijing Instrument Factory (Group), Shenyang Xingxing Industry Co., Ltd., Nanjing Vacuum Pump Factory, Guangdong Vacuum Equipment Plant Company Limited, Shenyang Sanhuan Vacuum Technology Research Institute, Shenyang Vacuum Machinery Factory, Linhai Precision Vacuum Equipment Factory, Wenling Vacuum Pump Factory, Taizhou Jiali Vacuum Equipment Co., Ltd. and Boshan Vacuum Pump Plant, etc. China's rotary vane pump production from The level of design to manufacturing, performance and quality have all matured. The quality of products produced by major companies is relatively stable, and the appearance quality has been significantly improved. The long-standing problems of fuel injection and oil leakage in the past have been controlled in recent years, and the performance of rotary vane materials has been improved. To a certain extent, the reliability of rotary vane pumps has been added. 2XZ-8A direct-connected rotary vanes produced by National Semiconductor Investment Co., Ltd. The pump is one of the few new rotary vane pump products in recent years. From the general speed pump to the high speed pump, there is a certain breakthrough in the technical level, which solves the aging and wear of parts under high temperature and high speed conditions. The old product in the rotary vane pump, belt pump, 2X-4 produced by Zibo Vacuum Equipment Factory Co., Ltd., 2X-15 produced by Beijing Instrument Factory (Group) and 2X-70 produced by Shenyang Hengxing Industrial Co., Ltd. in 2001 In the tests of the year, the original quality advantage was maintained, the quality was stable, and the operation was reliable. These products had long been favored by users and became the representative product of the company. The current overall quality level of the rotary vane pump products can meet the requirements of the current industry standards. Belt pump (General speed pump) is about 80%; Direct pump (high speed pump) is about 50% The main problems are the following aspects: 1.21Pa pump speed is too low, resulting in pumping efficiency (measured pumping speed theory Speed) does not meet the standard requirements. According to the standards, the pumping efficiency of the rotary vane pump at the inlet pressure of 2 Pa shall be more than 45%. This indicator characterizes the pumping capacity of the pump in the defective product of the rotary vane pump. 80% is due to the low index. Part of the reason is due to the fact that the inlet diameter of certain products has not been implemented in standards, resulting in insufficient conduction; the other part is due to parts processing and assembly problems, causing leakage of the pump leakage and increased resistance of some companies because of the lack of pumping efficiency The detection conditions of the indicator, the product is not well tested and monitored at the factory, so that the indicator could not be improved and solved for a long period of time. Another major issue is the injection and oil leakage. This indicator is an important indicator related to environmental protection. In recent years, major domestic manufacturers have made great efforts to solve the oil injection and oil leakage problems of the rotary vane pump. The results have been significant, such as the installation of an oil mist separation device and the oil blocking device. , Improve the processing accuracy of the drive shaft, replace the imported shaft seals and so on. But there are still about 20% of the rotary vane pump oil injection, leakage pool 1.3 pump noise does not meet the standard requirements such as the standard 2XZ-2 rotary vane pump, noise should be the main performance indicators of the slide valve pump limit pressure limit full pressure, China's slide valve pump products after years of market training, its main technical performance such as extreme pressure, pumping speed, pumping efficiency and other indicators have been greatly improved, pump noise, no fuel injection, no oil leakage and other indicators have also been improved For example, the production of slide valve pumps from Zhejiang Vacuum Equipment Group Co., Ltd. is large in variety and stable in quality. It has been favored by customers for many years and exported in batches.

In recent years, manufacturing companies and colleges and universities have made effective explorations and efforts to solve the problem of noise and vibration of slide valve pumps from the theoretical perspective to the processing technology.

The mechanism of the noise formation of the slide valve pump is relatively complex, and is generally considered to be the result of multiple interactions, such as exhaust noise, mechanism vibration and excitation noise, motor and bearing noise, and impact noise of pump oil. New technologies and new structure slide valve pumps designed to reduce pump vibration and noise have been continuously developed in the country. Such as: change the valve structure and material to reduce exhaust noise; using three-cylinder type slide valve pump, so that the smooth operation of the slide valve pump, reducing vibration and noise. Recently, a new type of product, the HGL-150 slide valve pump, passed the qualification. The product adopts a new structure in three important parts. The production process is complete with production equipment. The product not only has a low ultimate pressure, but also reduces noise by 6dB from the standard value, and operates. Smooth, without anchor bolts. The quality of the rotary valve pump has been improved to a new level, shortening the gap with foreign products. Some manufacturers have also noticed the difference between the appearance quality of slide valve pumps and foreign products, from the appearance of the product design and the pump body. Grasping the quality of castings, making it instrumental to the development of the instrument to modernize the appearance of the product design, the surface of the pump body is not putty, spray paint after assembly, giving a fresh feeling.

In spite of this, there is still a large gap between domestic slide valve pumps and foreign products mainly in the following aspects.

Noise and vibration. Such as H-150 spool valve pump, most domestic products use anchor bolts, otherwise it will crawl due to vibration. Due to the wide range of noise specifications stipulated by the slide valve pump standard, the passing rate of this indicator in recent years is nearly 100%, but compared with the products of foreign advanced countries, the noise is generally higher than 5dB, so the reduction of the slide valve pump The noise is still the direction of the manufacturer's efforts and the noise indicators specified in the standard should be revised when appropriate to facilitate further noise reduction of the product.

When the fuel leakage pump starts, the fuel injection is serious, and the oil leaks after operation. Most products have this problem. Stopping the pump and returning the oil is serious, causing difficulty in starting, making the motor overload stability and reliability poor. Due to the backwardness of production and processing equipment, not only the production efficiency is low, but also the interchangeability of components is poor, affecting the product Roots pump is a medium-vacuum pump, and the ultimate pressure can reach the current technical standards of the Roots pump. The main technical performance indicators are: ultimate pressure, The maximum allowable differential pressure for pumping speed and the maximum compression ratio noise for zero flow.

In recent years, the production of China's Roots pump has made some progress in the process equipment. The main production companies use the processing center's special equipment to process the main components of the pump, which has improved the quality and interchangeability of the products to some extent. Enterprises to improve gear accuracy, use of imported bearings, reduce the noise of the pump, so that the overall performance of the Roots pump has improved but due to the uneven quality of Roots pump production, the quality of the current domestic Roots pump products are quite different, the old production company products The performance index meets or exceeds the standard requirements such as the zero flow compression ratio gas flow rate is zero, the ratio of the Roots pump outlet pressure to the inlet pressure is an important indicator that directly reflects the design of the Roots pump line design, profile processing and assembly level This indicator shows the pumping capacity of the Roots pump. Such as the Z-300 Roots pump, the standard stipulates zero flow maximum compression ratio> 35, some products can reach 50 or more, and some products can only reach about 30 or so In addition, the processing of the main parts of the Roots pump pump parts is selected. Accuracy has a direct impact on the life of the pump. Domestic Roots pumps still have about 30% of unqualified products according to the current standards. If compared with the international advanced level, the overall performance gap is larger and the main performance is as follows.

1 Shaft seal oil leakage Serious domestic shaft seal cannot withstand long-term operation, and oil leakage is more common than vibration noise. Some products have poor balance, and some have insufficient gear and bearing accuracy.

According to industry standards, the zero-flow compression ratio and the maximum allowable pressure difference of some products do not meet the requirements of the standards. Some enterprises have poor production processes and equipment, and can not guarantee the accuracy and assembly accuracy of components due to the above problems, which are expressed as Roots. The pump is not reliable and the failure rate is high. Some pumps have to be serviced for several months, and it is a great contrast to the maintenance of the German LH Roots pump for several years without maintenance. In addition to the quality problems mentioned above, the volumetric vacuum pump has common quality problems as well as the durability of the product. The reliability is poor. For some objective reasons, more than 99% of the pumps are not tested for reliability. The manufacturer does not know much about the reliability indicators of their products, and the fault-free operation period specified in the current standard (similar to the life test). Also, it only operates under no load, and it is far from meeting the requirements of endurance test and reliability test. Therefore, the problem of high failure rate of the product has not been effectively solved. In addition, the leakage of water, the product label and the actual situation do not match the screw looseness, The motor belt is over-tight or too loose, the gas ballast device of the rotary vane pump and the slide valve pump has not obvious effect or failure, etc. The problems are also more common. The performance quality of the vacuum pump depends not only on the manufacturing plant itself, but also on the quality of the vacuum pump. Has played a vital role, such as bearing gears, dynamic seals, static seals, motors, vacuum pump oils, etc. Empty pump manufacturer of high quality ancillary products to improve the quality of products is very effective.

In short, the production of domestic vacuum pumps is still relatively crude in design, manufacturing, assembly and testing compared with the advanced level in foreign countries, and has not entered the fine grinding environment. Although China's vacuum-recovery equipment also has the advantage compared with foreign advanced countries, A certain gap, but after the joint efforts of people of insight in the vacuum community and the vast majority of users, this gap is continuously narrowing. The vacuum industry is aiming at the international advanced level. Endeavor Shanghai Bohui Vacuum Equipment Co., Ltd. Recruitment Shanghai Bolcon Vacuum Electronics Co., Ltd. The company specializes in the production of rotary vane vacuum pumps, halogen leak detectors and other products. Now the following personnel are employed due to business development needs.

Vacuum Technology Consultant 2 (Part-time) Vacuum Technician 2 Electronic Technology Consultant 1 (Part-time) Salesperson 2

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