Cushion pin device for press

16:

• A control method of a cushion pin device for a press, wherein the cushion pin device includes a cushion pad, cushion cylinders mounted on the cushion pad, main pressure control units having main logic valves, each of which is mounted on an upper side of a corresponding cushion cylinder, a main pressure conformity pipe that is mounted by connecting the main logic valves to each other, and relief pipes, each of which is mounted by connecting one lower side of the corresponding cushion cylinder and one side of corresponding main logic valve, a sub pressure control unit that is interconnected with the main pressure control units and the cushion cylinders,
• the control method comprises:
• selectively supplying working fluids of the cushion cylinders to each other through the main pressure conformity pipe by operation of the main logic valves respectively;
• and
• returning through the relief pipes the working fluid that flows into the corresponding main logic valve to the corresponding cushion cylinder when the working fluid that flows into the corresponding main logic valve is equal to or higher than a preset pressure while keeping each cushion cylinder at a same pressure as each other through the main pressure conformity pipe.

17:

• The control method of claim 16, further including:
• measuring an output value of a linear scale;
• and
• operating the sub pressure control unit in accordance with a measured output value of the linear scale.

18:

• The control method of claim 17, wherein the sub pressure control unit includes:
• a sub logic valve installed on the main pressure conformity pipe;
• and
• a sub pressure adjustment pipe that selectively discharges the working fluid that flows into the sub logic valve from the main pressure conformity pipe to each of the relief pipes to control a flow rate of the working fluid in the main pressure conformity pipe,
• wherein the sub pressure adjustment pipe is connected to each of the relief pipes provided in the each of the cushion cylinders at both sides of the sub logic valve.

19:

• The control method of claim 16, wherein the sub pressure control unit includes:
• a sub logic valve installed on the main pressure conformity pipe;
• and
• a sub pressure adjustment pipe that selectively discharges the working fluid that flows into the sub logic valve from the main pressure conformity pipe to each of the relief pipes to control a flow rate of the working fluid in the main pressure conformity pipe,
• wherein the sub pressure adjustment pipe is connected to each of the relief pipes provided in the each of the cushion cylinders at both sides of the sub logic valve.