Metal founding – Means to shape a forming surface – Including means applying vacuum directly to mold material
Patent
1987-10-07
1988-04-26
Godici, Nicholas P.
Metal founding
Means to shape a forming surface
Including means applying vacuum directly to mold material
164195, B22C 1522, B22C 1528
Patent
active
047398205
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to an apparatus for simultaneous making of matching mould parts with a horizontal parting face. The apparatus includes a shared pattern carrier, to which an upper and a lower half pattern are secured, moulding chambers being provided above and below the pattern carrier, said moulding chambers having movable squeeze plates for post-compacting as top and bottom, respectively, whereby the moulding chambers can be impulsively subjected to vacuum for sucking in moulding material, preferably moulding sand, through the squeeze plates, and whereby the moulding material is fed to the lower moulding chamber through an essentially L-shaped down pipe, whose upper end is connected with a materials container above the moulding chambers, and whose lower end is connected with the squeeze plate in the lower moulding chamber.
BACKGROUND ART
An apparatus of this type is known from German Patent Specification No. 2,653,788. However, it has been found that the vacuum provided in the moulding chambers is insufficient to overcome the friction in the moulding material, which is compacted in the lower portion of the down pipe. The weight of the moulding material in the down pipe will be added to the compressive force provided by the intake force from the moulding chamber under vacuum, which gives rise to caking of comparatively moist moulding material in particular.
SUMMARY OF THE INVENTION
The object of the invention is to provide a solution to the problem referred to above, so that a comparatively small vacuum in the moulding chamber will ensure satisfactory filling of the moulding chamber, meaning that when using post-compaction via the movable squeeze plate, mould parts with uniform density and strength are achieved.
According to the invention, this is achieved by an apparatus of the type described in the opening paragraph and characterized in that at least one air intake opening is provided at the lower corner of the L-shaped down pipe. Thus, it is possible to whirl up the moulding material in the area where it tends to cake, and the air quantity sucked in due to the vacuum will reduce friction between the moulding material and the side faces of the down pipe. It becomes feasible to use a comparatively tall down pipe, so that the weight of the moulding material in the pipe can be used to provide a compressive force, which--during the filling operation--will contribute to pressing the moulding material into the moulding chamber. This permits the use of a smaller vacuum than in apparatuses where the fall in the down pipe is smaller.
In an embodiment of an apparatus according to the invention, a screen plate is placed above intake openings, while forming a slot at the bottom of the down pipe in its entire width and opening towards the channel below the moulding chamber.
Placing a screen plate above the intake openings results in directional air intake through the openings, and during the impulsive intake of moulding material, a sort of air cushion will be generated at the bottom of the lower portion of the L-shaped down pipe, i.e. the channel below the moulding chamber. The friction between the moulding material and the bottom face of the channel is thus substantially reduced.
According to the invention, the inlet opening in the lower moulding chamber may be a slot provided centrally in the squeeze plate with a length equal to the moulding chamber.
It has been found that the provision of a centrally placed slot reduces friction in the connecting area between the moulding chamber and the inlet channel. The internal friction between the particles of the moulding material will give rise to a laminar flow through a comparatively narrow centre area, while a large opening equal to the cross-section of the flow channel will give rise to turbulent flow conditions.
In an embodiment preferred in practice, a connecting part tapered in V-shape is provided between the lower portion of the down pipe and the slot in the squeeze plate, said connecting part having a width equal to the slot.
This incre
REFERENCES:
patent: 4182395 (1980-01-01), Buhler
patent: 4620584 (1986-11-01), Witt
Jensen Claus T.
Johansen Joern E.
Kauserud Haakon
Batten, Jr. J. Reed
Dansk Industri Syndikat A/S
Godici Nicholas P.
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