Recycling old sand in foundry without intermediate old sand storage - using belt weigher to determine amt. of dry additives and water to be added

摘要

A foundry process is described in which the forms, after casting and solidifying, pass through a drum in which they are broken up, cooled and mixed. The old sand is then sepd. from the castings and passes onto a conveyor. The conveyor is equipped with a weight device which determines the throughput of sand, and transmitts this information to a controller which regulates the flow of additives to the old sand as it passes over a second conveyor. The mixt. of old sand and additives such as coal powder, clay powder and powder and sand are then elevated and pass through a mixing drum in which the correct quantity of water is added. The mix is then stored in the form sand store. Pref. the additives are placed on top of a layer of old sand on the conveyor belt, the feed rate for the additive being determined by the speed of the belt and the clearance between the bottom of the feed hopper for the additive and the upper surfaces of the material on the belt. These factors are regulated by a control device in proportion to the feed rate of the old sand as measured by the belt weigher.