In various oil circuits, in order to connect the oil pipe with the pipe joint, it is necessary to rivet the nozzle at both ends of the pipe into a trumpet shape to match the conical surface of the pipe joint, and then press it with nuts to realize the sealed connection.

The nozzle expander is often used to expand the nozzle into a horn shape, and the tool for expanding the horn is shown in figure 1-86. It consists of a pipe clamp [Figure 1-86 (a)] and a nozzle expander [2, 3, 4 and 5 in Figure 1-86(b)]. The pipe clamp is equipped with two splints with living hinges. There is a hole slightly smaller than all kinds of oil pipes between the two clamping plates, and the orifice has a 60-degree chamfer. The two outer surfaces of the splint are inclined planes, which are matched with the inclined planes of the inner frame of the dilator.