CTS antenna vacuum brazing

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With the continuous improvement of modern electronic equipment’s requirements for high reliability, high performance, light weight and miniaturization, the importance of advanced welding technology has become increasingly prominent. CTS (Continous Transverse Stub) antenna assembly is a thin-walled (partial) component with good inner wall roughness, high precision and complex shape. The development of high-precision CTS antenna components requires precision welding technology. Paying attention to the development of this technology can significantly improve the manufacturing level of military electronic equipment and shorten the development cycle. Therefore, the special connection method has become the key to the precision manufacturing of CTS antenna components.

Special welding technologies such as vacuum brazing, diffusion welding, friction stir welding, linear friction welding, and high-energy beam welding have been developed and applied in precision welded components. In order to obtain high-quality or high-performance joints that match the base metal, vacuum brazing is currently the most effective connection method, mainly in the welding of complex components and refractory materials. With the improvement of equipment manufacturing level, the enhancement of quality awareness and environmental protection awareness, and the demand for complex parts structure, vacuum brazing technology, as an advanced connection method, has received due attention due to its high precision, beautiful shape and stable performance.

Analysis of Structural Characteristics of CTS Antenna Components

Microwave antenna is the key module of radar and microwave measurement equipment. However, with the continuous development of microwave communication technology, antenna manufacturing technology has become a bottleneck restricting the development of equipment. Different from other electronic products, the overall function and electrical performance of the microwave antenna are mainly guaranteed by the structure of the feed network. Therefore, the design, process and manufacturing of the feed network are the key technologies in the manufacture of antenna products. The final performance of the antenna is related to the size and position accuracy of each column of antennas after assembly and welding. At the same time, it is necessary to ensure the tightness of the welding and the continuity of the welding seam between the antennas of each column. Defects such as unfused, air holes, and welding flashes are not allowed.

Vacuum Brazing Process

During vacuum brazing, the workpiece is mainly heated by thermal radiation. The process parameters to be controlled during vacuum brazing mainly include heating rate, brazing temperature, holding time, vacuum degree, etc. These process parameters should be optimized and strictly controlled in practice. In addition, the specific situation should be analyzed in detail during processing. Generally, the vacuum brazing process of aluminum alloy requires high cleanliness and high vacuum degree. Therefore, the vacuum brazing process is roughly as follows:

Before vacuum brazing, according to the drawings and process requirements, put the prepared brazing material in the matching gap of each part to be welded in advance, assemble each part into an antenna assembly, and fix and fasten it with stainless steel tooling. When tightening, use a feeler gauge to carefully plug the brazing contact surface of each part, adjust to a suitable gap, and clamp the welding surface with a stainless steel elastic chuck, and then put the assembled antenna assembly into the effective temperature uniformity area of ​​the vacuum furnace. , It is strictly forbidden to avoid the workpiece and fixture from contacting the inner wall of the brazing furnace, and the placement should be smooth and gentle.

The brazing process parameters of the product are set, and the process parameters are designed as 3 stages of heating and heat preservation after the vacuum brazing furnace is evacuated. That is: the first stage of preheating, constant temperature, and heat preservation. In this stage, the temperature rise should be uniform to avoid deformation and dislocation between parts due to the impact of large temperature difference. The second stage is energy storage, constant temperature, and heat preservation. This stage is mainly through heat preservation, so that the temperature between the parts is stabilized at a higher pre-welding temperature and is ready for welding. The third stage of brazing is constant temperature and heat preservation. In this stage, the welding time should be strictly controlled. If the time is short, the brazing filler metal will not be fully melted, resulting in incomplete penetration of the workpiece, resulting in the formation of porosity; if the time is long, the brazing filler metal will flow freely, and a weld tumor will be formed in the signal geometry channel.

Brazing process curve:

When the vacuum degree reaches 1×10-3Pa, the process curve shown in the figure is executed. After welding, the furnace is cooled to 60°C, the furnace is opened to take out the workpiece, and the fixture is removed.

Conclusion

In the brazing of high-precision antenna components, through the control of the processing of the brazed component unit, the design of the brazed joint, the design and optimization of the process parameters, and the overflow of the solder, the realization of up to 21-layer components with complex structures Vacuum brazing of units. It can be seen that vacuum brazing is an effective connection method for aluminum alloy components, but there are many influencing factors, especially when some components with special requirements are actually produced, it is necessary to design the tooling and determine a reasonable process curve according to the structure of the part itself. And constantly optimize and strictly control each link. With the development of antenna and radar technology, there will be more demands and requirements for precision welding technology. The vacuum brazing method and key points used can be used as a reference for the manufacturing process of the same type of 3A21 aluminum alloy precision radar, antenna and microwave devices, which can improve the yield and reduce the manufacturing cost.

Equipment selection: The RHVB series vacuum brazing furnace produced by SIMUWU is a high-quality product for the vacuum brazing process of tools and molds. The good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum brazing process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum air quenching furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.