GB190107733A - Improved Apparatus and Process for Making Dental Crowns. - Google Patents

Abstract

7733. Wheatley, W. H., [Brewer, B. B., and Burfeind, W. M. H.]. April 15. Stamping.-Relates to the production of dental crowns. A gold disc is first reduced to a cup in the apparatus shown in Fig, 3. A plate e, mounted freely and retained by a nut on a cylindrical part d of a shouldered conical stand a, is formed with a graduated ring of holes g with corresponding mandrels i carried by an inner ring of holes. The required hole g is brought between two radial anvil-like supports k by turning the plate e. A catch spring on one of the pieces k engages recesses in the cylindrical surface of the plate e. The formed cup is swaged in the apparatus shown in Fig. 6. The cup r is supported in a central hole p on a lead thimble q, and molten lead or other soft metal t is poured round it, a wooden stick being placed temporarily in the cup to hold it in place and exclude tho molten metal. The stick is then removed, a fusible form u is placed in the cup r, a disc v of lead or paper is fitted into the hole p over the cup r and metal t, and the whole is placed on an anvil and a punch is driven down the hole p, until the recess in the thimble q has been completely closed. The metal t is removed from the crown by expanding or opening it from the centre so that the crown drops out, by cutting three or four recesses with nippers, the edges of which are bevelled on both sides and applied radially to the metal. The form u is then removed by fusion.