## 1 Introduction
The research presented by the authors shows the connection made by means of four symmetrically arranged punches around the tube, with a special geometric shape ensuring the greatest possible strength of the joint. The forming depth of the punches was experimentally selected. In the work of [PERSON] [11], the process of performing the FEM analyses before making the connection was presented, which illustrates the joint manufacturing process. Moreover, the author specified the values of the obtained stresses. The prepared joint requires applying a force of 700 N to the system. [PERSON] et al. [12] presented the nonlinear plastic crimping analyses. On the other hand, the optimization of clamp connections is presented in [13]. Traditional methods of tube forming process are based on the use of a punch and a die. However, there are methods that allow the tube collar to be closed, which can be used to create a flanged joint with the plate. On the other hand, the authors of [14] presented the process of forming the end of the pipe. The forming of the collar in the described method is based on a complex movement consisting of a vertical movement and a rotary movement of the tool. Forming is performed with a cone-shaped tool [15]. Investigators of these articles find that there is a need to control the process parameters along the crimping. In [16], the author used the aluminum alloy 6060 T4 with an outer diameter of 38 mm and a wall thickness of 1 mm. The results of the presented experimental study were analyzed by FEM. The author presented the optimization of the shape of the tool, which determined the proper geometry of the tool. The automotive and aviation industries absolutely require the creation of connectors with appropriate quality parameters. In serial production, the economic sphere of the issue is also important. Therefore, it is crucial to choose the right connection technology, including the correct operation of the devices used for the production of these connections. The success of a fixed joint depends to a large extent on the appropriate process parameters, their control, and the input material itself [17; 18]. The industry of construction of heat exchangers is based on the use of aluminum alloys as a building material. This material joining process can cause many difficulties. Meanwhile, considering the joining materials with different characteristics, such as the aluminum plate with steel parts, many difficulties can be encountered when using traditional methods [19; 20; 21]. There are many other options for joining aluminum alloys, such as friction welding, joining by adding an adhesive, welding, mechanical clamping, and hybrid joining [22; 23]. In the mechanical process of clinching sheets, there is no need to make additional holes or introduce additional fasteners. Moreover, the joint is insensitive to surface cleanliness and roughness problems. Furthermore, a significant advantage is the lack of the influence of heat and related deformations [24]. Another noticeable advantage is the relatively short execution time, which is less than 1 s. The first patent related to the production of a joint by forcing two sheets parallel to each other was created in 1897. However, the development of this technology related to this joint gained industrial momentum only after 1980. This process has adopted the name of clinching all over the world, which is graphically based on pressing one part into another without the use of a connector. To make the joint, it is necessary to use a punch and a die [25]. However, clinching and other connections based on plastic deformation needs to deal with the friction between the materials. [PERSON] et al. [26] investigated the clinching process with different friction factors. Their findings led to the conclusion that the friction force has a significant influence on material flow during the process. Neutralization of leakage in the industry is very important, due to the fact that some of the researchers try to find the best solutions to act against them.