GB802135A - A method and apparatus for producing an accurately dimensioned pattern of an object it is desired to reproduce - Google Patents

Abstract

802,135. Moulding replicas. BRIGHT, T. J. R. Dec. 21, 1954 [Dec. 31, 1953 ; Dec. 31, 1953 ; Dec. 16, 1954], Nos. 36364/53, 36388/53 and 36522/54. Class 87(2). [Also in Group XXII] In a method of producing a pattern of an object 1 which it is desired to reproduce, the object is partially immersed in a mouldable material A, Fig. 9, which is converted to a solid state or allowed to solidify, further mouldable material B, Fig. 10, is added and solidified, the female mould parts thus formed are separated and the objects removed, a parting plate 15 interposed between the said mould parts, Fig. 11, and a third mouldable material introduced into the mould cavity or both sides of the parting plate. The third mouldable material is then solidified or allowed to solidify and the pattern and its associated parting plate removed. The object 1 is first mounted in a hole in a plate 4 by means of a ceramic or other filler, which plate and filler, which may be composed of a number of parts, are removed after the mouldable material A has solidified. Holes 17 in the parting plate connect the pattern portions on both sides of the plate. Suitable mouldable materials are wax, slurrys, thermoplastic or thermo-setting resins or compounds including such resins, and low melting point alloys. For example the material A may be a low temperature melting alloy, the material B a wax, and the third some other suitable material. Alternatively the materials A and B may be low melting alloys having different melting points and the third material a wax. The pattern may be used to produce a partible ceramic or other high temperature resisting mould. To prevent adhesion the object, the parting surface of the material A, and the mould cavity may be treated with a parting medium such as graphite. The first Provisional Specification refers to the use of multi part patterns with the parts made of different materials such as materials which melt at different temperatures, or one part of frozen mercury and one of a low melting point alloy, or a parting strip of e.g., nylon. The method is stated to be suitable for the manufacture of dies and tools and in one embodiment, the object to be reproduced with the help of the finished die or tool is partially immersed in a low melting alloy, a parting medium applied to the surface of the alloy and mercury or an alloy containing a high proportion of mercury poured into the container to totally immerse the object. The mercury is then frozen, the mercury and alloy parts removed from the object, invested by dipping in ceramic slurry and then run out. Specification 802,134 is referred to.