To make holes etroits, for example, holes of grease or aeration, in a wall of the pieces thick and model, in particular model lost, for the implementation of this

摘要

1455996 Producing a casting having an elongate bore therein; making drills; destructible patterns AUGUST LAPPLE GmbH & CO 6 Dec 1973 [7 Dec 1972] 56507/73 Headings B3F, B3A and B3G A casting having an elongate bore therein is made by anchoring an insert in a mould, casting metal around the insert, and then machining away at least part of the insert to form the bore. The insert may be made of graphite and may consist of two parts 12 and 13, the part 12 being machined away and the sleeve-shaped part 13 remaining in position in the finished casting. The mould 11 is formed around a destructible pattern 10, e.g. of polystyrene, the ends of the insert becoming anchored in the moulding sand. After the casting has been removed from the mould and a part of the insert has been drilled away, the end of a pipe (28) may be inserted into the sleeve part and glued in position. Alternatively, the end of the sleeve part 13 may be provided with a thread to facilitate connection of a pipe thereto. The method may be used to manufacture a tool punch provided with vent ducts (2), (3), (4) and (5), Fig. 1 (not shown).