A blank mold valving system for supplying vacuum/counter blow air to a blank mold of an I.S. The system includes an exhaust valve displaceable between open to exhaust and closed positions, a vacuum valve displaceable between open to vacuum and open to counter blow positions, and a counter blow valve displaceable between closed and open to counter blow air positions. A control operates the exhaust, vacuum and counter blow valves in a first deenergized mode wherein the exhaust valve is in the open to exhaust position, the vacuum valve is in the open to counter blow position, and the counter blow valve is in the closed position; in a second vacuum mode wherein the exhaust valve is in the closed position, the vacuum valve is in the open to vacuum position, and the counter blow valve is in the closed position, and in a third counter blow mode wherein the exhaust valve is in the closed position, the vacuum valve is in the open to counter blow position, and the counter blow valve is in the open to counter blow position.
A blow mold assembly for an I.S. machine for blowing a parison of glass and cooling the blown parison into a formed bottle which can be removed from the blow mold. A blow head is lowered onto a blow mold and final air is applied. The blow head is lifted a selected vertical distance above the top surface of the blow mold to an exhaust position allowing cooling air to escape from the blow mold. The selected vertical distance is selected so that at least a minimum pressure will continue within the formed bottle. The blow head is maintain at the exhaust position for a predetermined time and then retracted. A first pressure is applied while the blow head is at the lowered position and a higher pressure is applied while the blow head is at the escape position.
