An accurate electro-hydraulic system is used to drive the pump. From one side, a jack applies load to punch with controlled loading rate and from the other side, another jack with an accumulator is used to control clamping force and grip the test piece. To check the punch displacement and stabilize the test speed (closed loop), a digital non-contact linear encoder is used for measurement and feedback. This method provides punch movement resolution of 0.001mm. An industrial PLC and special modules provide the possibility of measuring and controlling some items such as reading the oil pressure value for better precision of punch loads, clamping force control, machine stoppage at sheet rupture, accuracy in applying load and adjustment of major controlling parameters according to standards. With an accurate pressure sensor, the punch force resolution reaches 1\/40000 of the machine capacity. The machine is also equipped with HMI touch screen display for easy reading of test data (such as time, date, load-displacement data, test intervals) in Excel format, test method parameters setting, automatic adjustment of loading rate and clamping force. The system can draw load-displacement graphs, record and send data to PC via Flash USB. A special hydraulic grip is used to clamp the sheet in order to distribute load in the clamping point evenly. Interchangeability of the punch and dies for different tests is another advantage of STE-200 in research projects. Special gauges are used to center punch and die during changing process. If it is needed to carry out the test at higher temperature, thermal dies can be mounted (on request), and hot forming up to 300\u00baC can be done (temperature controller modules should be installed in advance and connected to PLC).<\/p>\n","protected":false},"excerpt":{"rendered":"