Abstract: The flow rate of melt flowing through each end face of a core toward the inner surface of a side dam in opposed relationship with each end face is variable by a side-dam-wise flow passage defined within the core, whereby various problems caused at the so-called triple-point zones can be substantially solved.

Abstract: In foundry manufacture of metallic castings it is customary to employ inserts to form elongate ducts whether rectilinear curved or branched ducts and whether of regular cross-section or varying cross-section, including enlarged cavities. A core insert is disclosed which has a wire formed outer tubular casing and an internal wire structure, the core insert being removable in stages. Removal is accomplished by first removing a central longitudinal wire, then any intermediate layer is removed and finally by uncoiling the outer tubular casing, which has preferably previously been wound in such manner and of such diameter wire as to avoid, so far as possible, any exaggerated surface undulations.

Abstract: The present invention relates to a method for forming a canal when moulding a metal block, said canal being defined by a core inserted into the mould. The method involves using a core comprising a tube of powdered or granulated refractory material held together by an organic binding agent, and a rod located within the tube, coating the core with a blacking agent prior to moulding, carrying out the moulding operation and simultaneously combusting the binding agent and leading off gases through the core, and finally removing the rod and clearing away the remnants of the tube in the canal formed. The invention also provides a core suitable for use in said method.

Abstract: There is disclosed a method and apparatus for providing optically pure glass blanks, tubing, crucibles and the like for use in forming optical waveguides, lenses, prisms, filters, lamp envelopes and the like. A glass layer is formed at a high temperature on a mandrel which includes a support rod or tube upon which is disposed a layer of refractory metal wire, gauze, foil or the like. The mandrel is so constructed that stresses, which heretofore have developed in the glass layer during cooling, are avoided, and the mandrel is easily removed from the glass layer, thereby forming a hollow glass cylinder that is free from cracks, checks and the like.