Charging dampers with pressurized gas via press fitting blockage

These shock absorbers have two separate phases that are separated by a plunger. The liquid phase is oil, and the gas phase is nitrogen. One of the most challenging steps in making these shock absorbers is injecting nitrogen gas. This research project aims to present the method of manufacturing and producing the gas spring aid more straightforwardly, which reduces the production time. In this method, the need for special welding devices is eliminated by eliminating the nitrogen gas injection hole welding method. In addition to the mentioned case, one of the advantages of this method is to eliminate the inner wrinkle of the shell with the help of spring and thermal stresses due to the welding process of the hole in the shell. This research used a pressure injection device to inject nitrogen gas into the shock absorber. This device first makes contact on the lower edge of the injection device with the shock absorber shell, and after making contact, nitrogen gas is injected into the shell through the hole on it. Then, the said hole was blocked with a ball held at the tip of the mandrel of the injection device by magnetic force. Considering that the ball's placement inside the hole of the shock absorber shell must be a press fit, so for the steel ball whose diameter was 4 mm, the diameter of the hole was considered 3 mm. A shell with a plunger and a piston handle was injected with nitrogen gas at a pressure of 2 MPa. With the help of a hydraulic press, its volume was reduced to a fifth, and the pressure of nitrogen gas became 10 MPa. In this case, the jack was subjected to this pressure for three hours, and no pressure drop was observed.