Development and research of a gas stamping device for making hollow products from a pipe billet

It is advisable to produce hollow thin-walled parts widely used in machine designs from tubular blanks. In existing methods cold forming of the tubular billet takes place for the production of hollow products. In this case, due to the contained plasticity of the blank, parts of complex shape are produced in several transitions. This raises the cost of their production. We have developed a new device for forming hollow products by heating a tubular billet. The device contains a combustion chamber and a working cylinder, separated by a piston. Heating and shaping of the workpiece is carried out under the pressure of the combustion products of compressed fuel mixture supplied to the cavity of the workpiece from the working cylinder. The study was conducted on the basis of well-known equations of thermodynamics and the equations of the heat balance of the process of gaseous fuel combustion. It was found that the ratio of the volumes in the combustion chamber and the working cylinder should range within 2.5...5, and the ratio of the volumes of the working cylinder and the cavity of the pipe billet within 2...2.5. This ensures an increase in gas pressure in the blank cavity by a factor of 25...32, as a result of which the gas pressure reaches 50...65 MPa, and its temperature 2300 °C. Due to this, the stamping process is carried out in the temperature range of hot processing, which makes it possible to stamp parts of complex shape in one operation.