Workpiece support device

A method for supporting a workpiece comprising:

• providing a plurality of drive pistons slidably engaged in a respective plurality of drive cylinders and adapted to move between an extended and a retracted position;
• providing plurality of control cylinders, each arranged adjacent a respective one of the drive cylinders, each including an upper control port, a lower control port and an outlet port, wherein the outlet port of each control cylinder is connected with a lower end of the adjacent drive cylinder;
• providing a plurality of trigger pistons slidably engaged in the control cylinders and moveable between a first position, wherein the upper port of the control cylinder is connected with the outlet port and the lower port is closed and a second position, wherein the lower port of the control cylinder is connected with the outlet port, and wherein the trigger pistons each include a push pin adapted to engage with the drive piston in the adjacent drive cylinder when the drive piston is in the retracted position to force the trigger piston to the first position;
• first connecting upper ends of a selected plurality of drive cylinders and lower ports of the control cylinders adjacent the selected plurality of drive cylinders to atmosphere;
• second connecting the upper port of the control cylinders adjacent a first drive cylinder of the selected plurality of drive cylinders with a fluid at a low pressure, wherein the drive pistons in the first drive cylinder is driven to the extended position;
• third connecting the upper ends of the control cylinder adjacent a second drive cylinder of the selected plurality of drive cylinders to atmosphere, wherein the drive piston in the second drive cylinder is in the retracted position and the respective trigger piston is in the first position;
• fourth connecting the lower ports of the control cylinders adjacent the first selected plurality of drive cylinders with a fluid at a high pressure and connecting the upper ends of the selected plurality of drive cylinders with a fluid at a medium pressure, wherein the drive piston in the first drive cylinder is forced in the extended position and the drive piston in the second drive cylinder is forced in the retracted position.

A method for supporting a workpiece comprising:

• providing a plurality of pneumatic pistons adapted to move between a retracted and an extended position when relatively higher pneumatic pressure is applied to upper and lower ends, respectively, thereof;
• providing plurality of pneumatic switches adapted to connect lower ends of respective ones of the pneumatic pistons to first and second ports, wherein the switches are driven mechanically by the respective piston, wherein, when the respective piston is in the retracted position, the respective piston is connected with the first port and, when the respective piston is not in the retracted position the respective piston is connected with the second port;
• first connecting upper ends of the pistons and second ports with atmosphere;
• second connecting the first port of a selected switch with a low pneumatic pressure, wherein the piston connected with the selected switch is drive to the extended position;
• third connecting the first port of a further selected switch with atmosphere, wherein the piston connected with the further selected switch is in the retracted position;
• fourth connecting upper ends of the pistons with a medium pneumatic pressure;
• fifth connecting second ports of the switches with a high pneumatic pressure, wherein the piston connected with the selected switch is driven to the extended position by the difference between the medium and high pneumatic pressures and the piston connected with the further selected switch is driven to the retracted position by the medium pneumatic pressure.