In iron and metal foundries as well as in steel foundries, some form of runner is generally used when casting the molten materials in the casting mold and chill mold, respectively. In iron and metal foundries, a casting mold is usually built up of a molding mass comprising, for example, sand, a binding agent and soot, and applied in a frame or box or cast iron or steel, i.e., a so-called "flask". The casting gate is, in the simplest case, shaped directly in the molding mass. However, for higher quality castings, special runners are arranged in the form of feeding sleeves and rising gates of a insulating material on top of the mold. This results in a better after-sinking with reduced shrinkage and better slag separation. When casting steel, the predominant casting method used presently is the so-called "bottom-casting" method, which provides for the steel to rise into the chill mold from below.
Casting of this type is characteristically done in a casting gate on a thick cast iron plate, the rising plane extending, for example, radially out from the lower end of the casting gate in grooves in the rising plane and from there up into the chill molds placed at the outer ends of the flow-through tubes.
Because the molten materials have a temperature during casting of approximately 1200.degree. C. for heavy metal alloys and 1200.degree.-1500.degree. C. for ferro-alloys, the runners must be made of a material that can resist these temperatures at least during the casting period, which may last from about ten minutes up to roughly a half an hour.
At present, the feeding sleeves and rising gates of the iron and metal foundries are generally made of a tamping clay comprising a mixture of sand and oil gravel and thus are rather heavy and cumbersome so that some form of mechanical assistance is necessary to build and erect these sleeves and gates. This operation is usually carried out on the spot and is an activity which is specifically distinct from other foundry work, and, for this reason alone, an activity that foundries like to avoid. Further, the organic material contained in the tamping clay used in these sleeves and gates produces a heavy smoke formation which is presently one of the most serious environmental problems associated with foundries.
In steel foundries, the runners used are generally fabricated of ceramic materials in the form of chamotte, joined as a brickwork, and usually enclosed in cast iron casings and in grooves in the rising planes respectively. Dry sand is packed around the bricked-in tubes in order to support the brickwork and to prevent the molten material from running out and causing damage, as the chamotte easily cracks through temperature shock when coming into contact with the hot molten steel. The use of this dust-casting sand is another environmental problem because of the silicosis hazard for personnel. Further, because of the cracking characteristics of the chamotte, the steel ingots are prone to be contaminated by ceramic material which is carried along by the molten material and thereafter encased in the ingots.
It is characteristic of the methods used prior to the present invention that the preparation of the runners used therein requires considerable work and is quite expensive. Further, as explained above, the preparation and use of such runners present substantial environmental problems. Further, casting gates, feeders and rising gates have comparatively large connections to the casting and for this reason it is necessary to add a considerable excess of molten material to provide "tight" castings. The hardened excess is thereafter separated as waste. The problem of waste and the difficulties associated with separating the excess material are of long standing in the art.
USPTO Backgrounds
USPTO Backgrounds