Film drawing II of the hottest biaxial stretching

2022-08-11
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Biaxially stretched BOPP production line film drawing (II)

we know that the closest dependence on equipment is the uniformity of film - macro thickness uniformity and micro polymerization uniformity, so we chose EDI die NDC thickness measurement. The die head used in the system is imported from EDI company of the United States and matched with the infrared thickness gauge of NDC company of the United States. Through the thermal expansion bolt in the die head, the film thickness is controlled to ensure the stable and reliable operation of the whole device

4. Longitudinal stretching system

the system has 10 preheating rollers, 4 stretching rollers and 2 setting rollers. The temperature field required for longitudinal stretching and stretching is given by the speed change and temperature of a series of rollers in the longitudinal puller. This longitudinal drawing scheme has been adopted by many BOPP manufacturers imported from abroad. The process is mature and reliable. Generally, Bo needs to improve the reliability of test results. The longitudinal drawing heating system of PP manufacturers is oil heating, and its heat source is electric heating. In order to save the production cost of BOPP, our company can use the horizontal drawing oil boiler for both purposes. The hot oil produced by the oil boiler is mainly sent to the horizontal drawing oven for heating, and the other part is sent to the vertical drawing as the longitudinal drawing heating heat source, that is, one furnace for both purposes, The heating system is equipped with a set of temperature control device to meet the temperature requirements of longitudinal drawing. From a technical point of view, both schemes are feasible, but they are selected according to different situations

5. Horizontal pulling system

the chain clip of horizontal pulling machine, the guide rail assembly is the key part of horizontal pulling machine (TDO). The chain clip is a sliding chain clip, which is mainly composed of clip body, clip handle and sliding seat. The number of complete machines is 1800. Each clip body is precision machined through 56 processes and has good interchangeability. Strict material guarantee and heat treatment process make the chain body have high mechanical properties. Smooth and dry sliding. The transverse drawing system adopts the methods of four zone preheating, three zone stretching, four zone finalization and one zone cooling. Its system heating is to heat the transverse drawing heating zone with 1.5 million kcal of oil boiler heating oil. Its temperature control is controlled by computer. The temperature control is stable and reliable, and the error is between plus and minus 1 degree, which meets the process requirements

we still affirm the form of electric heating, and the two heating schemes can be selected according to the situation

we have carried out tests on various structures of the static pressure box used for horizontal tension. According to the difference of the characteristic curve of the centrifugal fan and the principle of hydrodynamics, we have determined the box structure. After the actual measurement, the pressure is stable and uniform

6. Traction winding system

in this system, we focus on corona treatment, which is related to the big problem of whether the surface tension of BOPP film is qualified and whether the surface tension is uniform. 8. The validity period of information release is big. In order to ensure the quality of the film, the corona treatment device of British Schumann company is selected for this corona treatment device, so as to meet the requirements of post-processing such as printing

the transmission device of the winding system pays special attention to three aspects. A. ensure that the film tension is kept constant during the whole winding process or decreases according to a certain law with the increase of the winding diameter (tension taper control). B. Ensure continuous winding and automatic roll change. When the winding roll is full, the automatic roll change program will be started, and the film will be cut off and smoothly transition to the backup winding roll for winding. Between the winding roll and the backup winding roll, the tension control and speed control conversion will be automatically completed. C. The winding follow-up roll adopts two working modes: Contact winding and gap winding, but it should be ensured that the follow-up roll can automatically retreat with the increase of coil diameter. When contacting the winding, ensure that the pressure of the follow-up roll is constant and adjustable

IV. current situation and expectation of domestic BOPP equipment

December 1, 2002. All kinds of signs on the universal experimental machine should be clear. The pre-test machine should be carried out for 6 days. The total time is 3 hours and 25 minutes, and it only takes 2 hours and 35 minutes from extrusion to film discharge. The speed of film discharge and film formation are unexpected. The thickness tolerance of large roll film after thickness measurement feedback control is put into operation is between 1% and 2%. As a result of the three-year efforts of the Far East employees with such achievements, some problems have also been found through this test, and now they are constantly improving

although our BOPP film production line is mature and successful, there is still a certain gap compared with the world advanced level, mainly because the production line of 50 ~ 10000 tons/year is still under development. The production line cannot produce the most advanced products of BOPP film. Nevertheless, we also have obvious advantages over the import line

first, flexibility. The equipment can be configured and designed according to user requirements and habits, including the settings of different plants and public works. It can save energy and investment while ensuring normal film drawing production

second, obvious price advantage. The domestic price is one third of that of the imported single machine. Because equipment depreciation and investment loan interest account for a large proportion in the product price. Therefore, the domestic line can reduce the film cost of products in a large range. Enhanced competitiveness

Third, our 5000 ton/year production line has certain scale benefits. It can also flexibly switch to different types of products

fourth, domestic lines have a faster construction cycle. Better and faster after-sales service. And the spare parts are easy to solve and the maintenance cost is very low

the BOPP production line in the Far East has the advantages of combining China's national conditions. It should be more adaptable to small and medium-sized enterprises than foreign companies in terms of environmental adaptation and user needs. But we should also see that our production line has many shortcomings. It is hoped that our domestic counterparts will jointly cherish the development of BOPP film production line technology in China

jointly carry forward national industry and contribute a love to China's Bo film industry. (end)

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