Development of leakage detection technology for th

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The development of metal container leakage detection technology

in recent years, the manufacturing technology of metal containers in China has made great progress with the development of economy. However, in contrast, the development of metal container leakage detection technology is significantly lagging behind, especially the leakage detection technology of steel barrels is still at the level of the 1950s and 1960s, which obviously can not keep up with the development pace of relevant technologies at home and abroad. Therefore, The leakage detection technology of metal containers in China needs to be improved urgently. In foreign countries with developed technology, the leakage detection of metal containers has been paid attention to by the legislature, which makes various relevant standards and norms more and more strict and clear. Therefore, in order to control and ensure the quality of the production and use of metal containers, our manufacturing enterprises must clearly understand the latest testing technology and methods

for metal containers, there have been many losses, pollution and hazards caused by leakage for a long time. With the development of society, we pay more and more attention to product quality, environmental pollution and human health, and require metal containers to achieve zero leakage. In foreign technical terms, the container must not leak, and the original pressure must be maintained inside the container. Such concepts are clearly defined in international standards

leakage inspection has three main purposes: first, to prevent the leakage loss of the contents of the container, so as not to affect the use effect of its products; The second is to prevent environmental pollution (dangerous or harmful substances) caused by leakage; Third, prevent the contents from being polluted, so that unreliable ingredients (ingredients that do not meet the requirements) reach the final consumer

over the years, various forms of bubble test have been commonly used in the leakage test of metal containers. The test method of this test is relatively simple, that is, put the container in water or smear soapy water on the common leakage place of the container, and then inject compressed air into the container to see whether a container placed in water bubbles, so as to determine whether the container leaks. This method can be found everywhere in our national standard. The power supply voltage of the hydraulic universal testing machine is 3-phase 380V. The electrical connection between the main body and the hydraulic control box has become a traditional and standard method. Although this method can detect very small leakage and find out its exact location, this method can not measure the accurate leakage rate, and has the following disadvantages: first, the detection efficiency is low and the labor intensity is high. In the modern automatic production line, it is almost impossible to detect all blister leakage of metal containers. Second, bubble leakage detection after inspection, The surface of the metal container has been covered with water, and the volume of the oil tank is only (x% Y (!% Y "z%) (OO) Pollution must be treated before entering the next process, otherwise the surface may rust or affect the subsequent coating quality

recently, a new type of container leakage detection system has been successfully studied in Italy. The system selects appropriate dry air leakage sensors, and is equipped with a test system controlled by computing devices and microprocessors. The system has an accurate and faster test cycle, which can adapt to more stringent anti leakage specifications

since 1974, Italian Bonfiglioli engineering company has specialized in the design and manufacture of leakage testing instruments, providing leakage testing methods for various packaging container industries, and has won a high reputation in the world. He has become the representative of container testing technology all over the world. In recent years, continuous research and development has made the company a world leader in the field of leakage testers. In order to meet the needs of various containers, their design and manufacture of each device comply with CE standards, which can meet the leakage detection of any container

at present, most of the domestic automatic barrel and can production lines are also equipped with relatively primary leakage systems, which are the result of digestion and absorption of foreign advanced technology and equipment, but in practical application, the effect is often unsatisfactory. The method is to use the principle of pressure attenuation, which cannot be detected for testing containers with objects and seals. At present, the latest technology is vacuum attenuation method, etc. Here is a brief introduction

I. pressure attenuation method

in this kind of test device, air is constantly blown into Bayer Material Technology: it is blown into the container until its internal pressure reaches a preset value, or after a predetermined time. During the test cycle, the pressure in the container is monitored. According to the change of

pressure and the comparison of its pressure value with the predetermined critical value, the container will be determined as qualified or unqualified

the principle of this test is: when the container enters a certain amount of compressed air, if the container does not leak, the compressed air will maintain the given pressure; If the container leaks, some of the gas will leak out and the pressure in the container will drop. This requires that before compressed air enters the container, pressure reduction, pressure regulation and pressure stabilization should be carried out first, so that the compressed air after pressure stabilization can be maintained at the precise leakage pressure point after entering the container. Then, a pressure relay (pneumatic element or trigger, pneumatic diaphragm logic element) with high accuracy is installed at the place where the air enters the container to measure the small pressure drop in the barrel and convert it into an electrical signal or a pneumatic signal to enter the execution system to notify the operator. Signal control execution system can also be used to pull the leaking container into the unqualified pile

second, vacuum attenuation method

in this kind of test device, the container being tested is sealed, and is usually filled with liquid, leaving only a pore on the top of the container. Insert a test head with an air seal ring at the mouth of the container. When pressurized, the air seal ring clings to the container wall to produce a strong sealing effect. The vacuum state is generated in the sealed test tank because the air is sucked away. In the whole test cycle, the special sensor controls the vacuum degree in the test tank from beginning to end

III. helium detection method

this kind of test device uses helium as a tracking gas, which can be sensitive to all parts of the container. The helium detection equipment consists of three parts: detection chamber, high vacuum chamber and gas analyzer. During the test, helium was fully diffused in the container. When the container filled with helium enters the vacuum chamber, start the vacuum pump, and the gas analyzer immediately displays the percentage of helium. A small amount of helium can trigger the rejection system. As soon as the alarm bell rings, the defective container is sent out from another conveyor belt

IV. load cell method

load cell method is generally used for the air tightness test of metal bag containers, and the air tightness of containers is tested by using load cells. The tested bag is placed on the lower conveyor, and the upper conveyor is above the bag, and its height is adjustable. The upper conveyor presses the tested area of the bag placed on the container on the lower conveyor. The movements of the two transmitters are synchronized. On the lower conveyor, there is a gravity balance at the inlet and outlet of the test cycle

the gravity balance at the beginning of the test cycle reads first. The size and elasticity of the bag determine the pressure on the bag generated by the upper conveyor

at the end of the test cycle, the gravity balance reads the second data. If the data measured by two balances are equal or less than the predetermined upper limit value, the bag can be considered as qualified. Otherwise, if the difference between the two readings is greater than the predetermined upper limit, the bag is unqualified

advanced leakage detection technology not only has high production efficiency and precision, but also has no impact on the quality of the container itself. Because the technology of China's metal container packaging industry, especially the barrel making industry, is relatively backward, most enterprises only pay attention to the production technology of metal containers, spend great efforts to improve and introduce intermediate production equipment, and have not paid enough attention to the leakage detection technology. Therefore, even if the production equipment is relatively equipment manufacturers, the detection technology remains in the original and backward state. This is an extremely abnormal phenomenon

at present, the leakage detection technology of metal containers in China needs to be improved urgently. It is hoped that when enterprises vigorously improve and purchase advanced production equipment, they will not ignore the improvement of leakage detection technology of containers. It is also hoped that relevant research departments and metal container production equipment manufacturing enterprises will pay attention to the introduction, digestion and absorption of foreign leakage detection technology, Make efforts for the early improvement of leakage detection equipment in China's metal container industry. Aluminum plastic composites are simply treated at a price 40% - 70% lower than that of pure plastics

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