2 Main contents and key technologies developed
2.1 The main content of the development
1) Complete the structural design of six varieties of FKB, FK W remote single flange pressure transmitter, FKD, FKX remote double flange differential pressure transmitter, FKE, FKY liquid level transmitter; including 48, 73, Design and development of 96 corrugated flange structure; design and development of flange type capillary and connecting structure parts.
2) Material selection, precision manufacturing and process programming of special parts.
3) The design of special welding process parameters of flange transmitter realizes the welding of 0.04mm, 0.06mm isolation diaphragm and corrugated flange.
4) Through the research on the characteristics of high temperature, ordinary and low temperature filling silicone oil
Research, complete the selection of silicone oil varieties, complete the determination and regulation of filling amount.
5) Design and development of special processes and special fixtures. 6) The formulation of standards for various models of FCX-A Ⅱ series intelligent flange transmitters.
2.2 Key Technologies
In order to ensure the performance and quality of the products and meet the technical standards and requirements of Fuji products in Japan, the following key technical problems have been solved in the design of parts:
1) Structural design. Design a remote measurement mechanism composed of isolation diaphragm, corrugated flange, remote transmission capillary, connection cover, connection port, silicone oil filling process hole and other parts to meet the on-site measurement process requirements and ensure the accuracy error, static pressure error, The one-way static pressure error, temperature additional error and other indicators conform to the technical indicators of Japan's Fuji FCX-A III series flange transmitter.
2) Design and CNC machining of corrugated flanges. The corrugated flange is a key measurement part in the instrument, and the welding dimensions of this part are required to be 48, 73 and the diaphragm with a thickness of 0.04mm and 0.06mm to be assembled and welded, and helium leak detection and 40kg pressure test are carried out. The key to the design of corrugated flanges lies in the selection of materials and the design of process parameters such as corrugations and welding grooves. We designed 48, 73 corrugated flange part drawings, and programmed on the CNC machine for precision machining.
3) The welding process parameters of isolation diaphragm and corrugated flange are determined by experiment. The most critical problem in the development of the six models of the FCX-A III series flange transmitter is the welding of the corrugated flange and the isolating diaphragm. 48. The thickness of the diaphragm of 73 is only 0.04mm and 0.06mm, which is very thin. It is easy to be melted and broken down during welding, and it has never been welded before. In foreign countries, the qualified rate of welding such a thin diaphragm and corrugated flange is only 80%. The welding process parameters mainly include the experimental determination of welding groove design, welding current, welding speed and other process parameters. It must be ensured that the effective welding of the minimum 0.04mm isolation diaphragm and the corrugated flange is not more than 110-4Pa ml/s under the vacuum degree of 10-5Torr, and the pressure after welding can withstand 40MPa.
According to the material of the corrugated flange and the material of the diaphragm, we have repeated experiments and explored the process parameters with many years of welding experience, and finally determined the process parameters of the welding on the plasma welding machine, such as welding current, rotation speed, clamping pressure, electrode diameter , nozzle diameter, etc. After welding and forming, it has passed the inspection of helium leak detection equipment, which provides a guarantee for the manufacture of the whole machine. Now our factory flange diaphragm welding pass rate can reach 80%.
4) The selection of the silicone oil test and the test of the filling amount determine that the transmission of the signal is through the measured pressure acting on the isolation diaphragm, and this signal is transmitted to the micro sensor, the selection of silicone oil and the quality of silicone oil filling , which directly affects the overall performance of the instrument.
The selection of silicone oil test mainly considers factors such as expansion coefficient, viscosity, density, and temperature range. The selection of filling fluid follows the following principles: 10# silicone oil (cold area), 50# silicone oil (ordinary silicone oil), high temperature silicone oil (250).
The filling and filling of silicone oil needs to be heated and degassed at high temperature in a vacuum state through special equipment. The vacuum degree of the system is above 1Pa (absolute pressure), which mainly overcomes the existence of gas phase and moisture in the silicone oil, and ensures the temperature and accuracy of the instrument. Otherwise, the zero point drift of the instrument will be caused.
The filling amount of silicone oil is mainly determined by calculation and experiment to determine the inner diameter of the capillary and the capacity under the membrane. The amount of silicone oil filling determines whether the signal can be accurately measured: excessive amount will cause the increase of temperature additional error, one-way error and static pressure error, etc., and the signal will not be transmitted if the amount is small. It is the key factor that determines the performance of the whole machine. After many tests and with reference to the mature filling process of the FC production line imported from Japan, the reference value is obtained. After the test of the production process and on-site users, the filling amount can meet the performance requirements of the instrument.
3 Data Analysis
After the performance of the whole machine is measured, the technical indicators of the instrument have reached the technical indicators of the imported instrument. Table 1 is the comparison between the test results of the localization of the FKX small flange remote differential pressure transmitter and the data of the enterprise standard and imported instruments from Japan.
FKX small flange remote differential pressure transmitter standard data After localization test data Japanese prototype data linearity 0.2%0.1 0.3 One-way static pressure 0.2%1.36 1.06 Static pressure 0.2%0.7 0.14 Temperature error A characteristic (%10) 0.640. 0270.03 Temperature error B characteristic (%10) 1.28
0.03
Through the above data analysis, it can be seen that the linear test, static pressure and unidirectional static pressure and temperature results of the localized FKX small flange remote differential pressure transmitter conform to the enterprise standard and reach the performance of the original Japanese instrument. indicators, to achieve our intended purpose.
4 Conclusion
In order to achieve 100% welding qualification rate of flange and measuring diaphragm, we will use electron beam welding machine and develop its process and tooling. The trial production of the prototype has been tested by the testing center, and all technical indicators have met the design requirements. The product has been used on site by Luolian and PetroChina Changqing Petrochemical Company for one year, which shows that its performance is stable, its reliability is good, and its precision is high.
