Erichsen Testing Introduction
The universal sheet device (Ericsson) is designed to check different sheets. This
device includes moulds and standard mandrels, which with a very accurate hydraulic
mechanism, the amount of force between the moulds and the movement speed of the
mandrel can be presented in a completely controlled and definable way. With the help of
this device, the behaviour of biaxial tension on the sheets can be studied and the Limiting
dome height (LDH) value is measured by the corresponding sensor.
This method is performed with a spherical mandrel.
This machine also has the ability to perform deep drawing of sheet metal using the Swift method with a completely flat mandrel.
The mechanism of the device consists of two independent hydraulic jacks (for clamping
and mandrel) and the function of the device is servo-hydraulic (motor and servo driver)
with feedback from changing the position and force to stabilize the speed. Applying
its force is performed in a close loop manner and the clamping force of the mold is
performed automatically with an independent definition. This device has the ability to
stop the test automatically (adjustable) after a crack occurs in the sheet.
Our Erichsen Testing machine detail
A highly accurate electro-hydraulic system is used for this machine in such a manner that a separate cylinder is used for punch load application with punch loading rate control while another cylinder with accumulator is responsible for clamping force control in the defined load of the specimen constant clamping. To reach precise punch movement control and test speed stabilization (close loop) a digital non-contact linear encoder is applied to measure and respond. This method provides a punch movement resolution of 0.001mm.
An industrial PLC and special modules provide the possibility to measure and control items like: oil pressure (more accuracy on punch load), clamping force control, machine stoppage at sheet crack moment, accuracy in applying load by slow mode and adjustment of major controlling parameters according to standard. With an accurate pressure sensor the punch force resolution reaches 1/40000 of machine capacity.
The machine is also equipped with HMI touch screen for easy reading of test data (time, date, load-displacement data, test times) in excel software, test methods parameters adjustment, automatic loading rate and clamping force. This system is also able to draw load-displacement graphs, record and send data to PC via Flash USB.
A special hydraulic grip is used for sheet clamping to have a constant load on the specimen during clamping. Easy changing of the punch and dies for different test is another advantage of STE-200 is research projects. A special gauge is used for punch and die centering during changing. For test in higher temperatures thermal dies can be installed (on order). Hot forming can be achieved up to 300˚C (additional accessories required) with provision for temperature controller modules and PLC connections.