Metal founding – Process – Shaping a forming surface
Patent
1981-01-22
1984-01-03
Hampilos, Gus T.
Metal founding
Process
Shaping a forming surface
164137, 164244, 164360, B22C 908
Patent
active
044237626
DESCRIPTION:
BRIEF SUMMARY
The present invention is concerned with a method for the production of a metal casting mould having a riser, and a cavity former and riser for use therein.
The use of riser sleeves in metal casting moulds is well known. Up to now, they have been located either by moulding directly on the pattern used to make the mould or subsequently by insertion into the top or cope part of the mould into a cavity formed by a loose pattern piece which has been removed from the top of the mould.
It has also been proposed to insert riser sleeves into open half moulds where the mould has a vertical parting line.
Because of the increasing automation of methods used for the production of casting moulds from moulding material such as sand, there is less access to the pattern plates at the moulding station, especially in the production of repetition castings. As a result, it is no longer possible to apply riser sleeves directly on the pattern plate, nor is it possible to locate a loose piece on the pattern plate to form a cavity into which is later inserted a riser sleeve.
When it is no longer possible to obtain access to the pattern plate an alternative procedure may be possible with automatic moulding plants which are equipped with a cope mould line which is synchronised with a drag line where cores are set into the drag. On the moving cope line, inverted cope moulds are accessible for additional work, so riser sleeves may be inserted in the inverted cope mould.
With riser sleeves which have been used hitherto this is either impossible or only partially successful. Known riser sleeves have a cylindrical or almost cylindrical outer surface for reasons partly concerned with their production technique and partly concerned with their function. Because of dimensional variations inherent in their method of production such riser sleeves cannot be inserted into a preformed cavity with sufficient confidence that they will remain in place securely.
Another group of riser sleeves, especially those which are closed by means of a cap at one end, have a positive taper from their base going up towards the cap, i.e. the outside diameter becomes larger from bottom to top and therefore they cannot be used for the subsequent insertion into the inverted cope mould.
One object of this invention is the creation of a new method for the production of a metal casting mould made of finely divided moulding material such as moulding sand which makes it possible to insert a riser sleeve readily and so that the sleeve remains securely in a preformed cavity.
According to the invention there is provided a method for the production of a metal casting mould having a riser, in which method a riser sleeve is inserted in a cavity in the mould, the cavity being formed by locating a cavity former in a body of particulate moulding material, compacting the material about the former, and removing the former, characterised in that the former is made oversize relative to the sleeve to be received in the cavity and has one or more recesses therein whereby the cavity is formed with at least one inwardly projecting rib-like formation of moulded material for gripping the sleeve when received therein and the former has a negative taper from bottom to top.
When objects such as riser sleeves are made in quantity to a predetermined nominal size, i.e. height and diameter, in practice the sleeves deviate from that nominal size. Such sleeves can still be used provided that they can be inserted in the mould cavities which are to receive them, and that once inserted they will remain in place.
By checking and recording the actual height and diameter of a particular nominal size of sleeve during the course of production it is possible to calculate the standard deviation in height and diameter from the mean values for those parameters for that sleeve.
The invention also includes for carrying out the method a former whose exterior has a plurality of radially spaced apart grooves extending between the top and towards the bottom of the former and whose outside diameters are larger than th
REFERENCES:
patent: 3815665 (1974-06-01), Baur
patent: 4131152 (1978-12-01), Ruddle
patent: 4141406 (1979-02-01), Wukovich
Schopp Helmut
Trinkl Gerd
Foseco International Limited
Hampilos Gus T.
Seidel Richard K.
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