The moving platen of the new control system of the hydraulic press will be controlled by the new programmable logic controller (PLC), and the leveling cylinder will be controlled by the new electro-hydraulic motion controller.

The electrical control engineer added, "we also have experience with other motion controllers. But compared with other products we have tried, the selected motion controllers are easier to integrate with PLC and provide more functions and flexibility. They can also carry out more accurate positioning and force control."

In order to provide position information, four leveling cylinders are equipped with linear magnetostrictive displacement sensors, which are connected with the synchronous serial interface (SSI) of the motion controller. In order to provide force information, each cylinder is equipped with two pressure sensors, one of which is connected to each cylinder port.

In order to maintain the cylinder level throughout the cycle, the motion controller is programmed to perform virtual gear transmission. This is the command issued by the motion controller, which enables each of the four leveling cylinders to accurately follow the movement of the spindle. While controlling the position of each cylinder, it also controls the force applied to each cylinder. This configuration supported by the motion controller is called dual loop position force control.

The operation of the hydraulic press includes three consecutive steps. The motion controller drives four leveling cylinders with magnetostrictive displacement sensors protruding from the father through three position and force control curve sequences. The three steps are:

1. Speed force: the leveling cylinder with magnetostrictive displacement sensor maintains parallelism when pushed downward by the moving pressing plate, and the speed is opposite to that of the moving pressing plate until it is closed on the glass fiber material.

2. Resistance: during the curing process, some of the processes also involve coating the glass fiber material. The leveling cylinder with magnetostrictive displacement sensor must maintain parallelism, which is opposite to the force maintained by the moving pressing plate, to ensure the parallelism control.

3. Stripping force: at the end of all cured profiles, moving the pressing plate will reduce pressure, and its weight will be borne by the leveling cylinder with magnetostrictive displacement sensor. The leveling cylinder moves from the start closed-loop position, while limiting the stripping force.

Article source: magnetostrictive displacement sensor http://www.delysensor.com