Development Of Pneumatic Catapulting Impact Testing Machine

At present, the catapulting impact testing machine, works mainly by threekinds of way: by mechanical means (gravity pendulum), by methods of hydraulicand pneumatic. Considering of these three ways, the structure of mechanical way istoo large, and the hydraulic way is difficult to obtain a larger impact velocity and itsstructure is complex, which is not ideal. But the pneumatic control system with itssimple and compact structure, prompt action, is paid more and more attention. Thisarticle aims to solve the various difficulties and problems encountered in thedevelopment of pneumatic catapulting impact testing machine, and eventuallydeveloped a pneumatic catapulting impact testing machine in line with nationalstandards.Repeat accuracy of the testing machine on the impact velocity is veryrigorous, and the error does not exceed±0.8%. In Simulink, models of thecatapulting process are combined with the analysis of the kinematics to develop theoverall design of the testing machine, including control programs, mechanicalsystems and pneumatic controlling parameters matching. At last, the systemaccuracy is reasonably allocated to every link.The mechanical structure design and processing of the testing machine hasbeen done, including workbench, the impact arm and the positioning table of theejection device. Workbench is used to place the measured object, the impact arm isused to give the impact speed required, and positioning table is used to fulfill themovement of XYZ axis and the rotation of XY plane angle (γ).Pneumatic and electrical control systems of the testing machine has been done.Pneumatic control program using the open-loop control, adjust the inlet pressure tocontrol the speed of the impact arm. The electronic control system consist of thehost computer and the lower computer. Data collection is completed by the lowercomputer (IPC), and the interactive interface is written in the host computer. Thehost computer and the lower computer communicate via TCP/IP protocol.Thecontrolling software of the testing machine has been developed. The software cancalculate the gas pressure inside the tank, according to the experimental requirements, and display and analyze the experimental results when the test is over.The testing machine works well, and meets the specifications of repeataccuracy of the ejection velocity. According to the velocity data measured in theexperiment, we corrected the catapulting velocity calculation module of thesoftware, and finally obtain the desired results.