AUTOMATIC FLOW RATE SWITCHING VALVE AND AUTOMATIC FLOW RATE SWITCHING METHOD, AND WORKTABLE

PROBLEM TO BE SOLVED: To switch automatically the flow rate of a fluid from an exhaust nozzle. SOLUTION: In the condition separating an object W from an exhaust nozzle 2, a flow rate switching valve 5 is raised by the compression air of an air chamber, and the flow-in ends 6ai of a large diameter hole 6a are closed by the inner peripheral surface 2c of the insertion 2b of the exhaust nozzle 2. As a result, the exhaust air from the exhaust nozzle 2 is made only the air passing through a small diameter hole 6d, and it is suppressed in a small amount. When the abject W comes to the position immediately upper the exhaust nozzle 2, the air pressure at the upper part 2a of the exhaust nozzle 2 approaches to the pressure in the air chamber, and the pressure difference between both sides is reduced, and as a result, the change-over valve 5 is lowered by its dead weight, and the flow-in ends 6ai of the large diameter hole 6a are separated and opened from the inner peripheral surface 2c of the insertion 2b. Consequently, a necessary amount of air is exhausted from the exhaust nozzle 2 after passing through the large diameter hole 6a, so as to reduce the friction resistance between a table plate 1 and the object W.