A New York based forging company required a lifting device to lift hot, forged rings from a furnace run out table and stack them on a cooling table. The lifter had to grip and transport the rings in a way that the integrity of the shape was maintained distortion free and the load was sufficiently supported. The ring diameter varies in size from 1.7 meters to 12.0 meters. The thicknesses range from 0.2 meters to 0.8 meters. The customer required that the user be able to operate the lifting device with a wireless pendant to maintain a safe working distance.
Hunter Lift's engineers calculated that three independent lifting tongs were sufficient to support the ring and maintain its integrity. Each tong has a gravity assist grip and open/close positions provided by a 5-ton electric cylinder. Each tong is mounted on an arm which swings open and closed simultaneously in relation to the ring diameter.
The arms are attached to a motor-driven acme screw which was sized to take the load generated from lifting the ring (up to 30,000 lbs). Indicators for proper alignment and grip are provided to ensure a ring is lifted when the tong points are in contact with the sides of the ring.