Metal founding – Means to shape a forming surface – Including means applying vacuum directly to mold material
Patent
1987-10-06
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
047398213
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to an apparatus for making mould parts with a horizontal parting face and of the type that includes a container for the moulding material, preferably moulding sand, a moulding chamber which may be subjected to vacuum, and which may be defined at the bottom by a pattern plate and at the top by a squeeze plate, whereby the moulding material is impulsively sucked into the moulding chamber through the squeeze plate and is post-compacted in it by advancing the squeeze plate with the pattern plate, which carries a half pattern.
BACKGROUND ART
In this type of apparatus, the moulding sand tends to bridge and clot in the inlet to the moulding chamber due to internal friction in the moulding material and to its friction against the walls of the container.
Attempts have been made to overcome the disadvantages by using a funnel-shaped inlet connecting the container with inlet openings in the squeeze plate above the moulding chamber, and by providing fluidization of the funnel-shaped inlet by applying pressure through nozzle filters in the funnel sides. An apparatus of this type is described in the Danish patent application No. 2945/84.
However, it has been found that the nozzle filters tend to block when using comparatively dry moulding material, and the positive supply of pressurized air is a complex measure making the apparatus more expensive.
SUMMARY OF THE INVENTION
The object of the invention is to provide an apparataus of the type referred to in the opening paragraph, where the danger of blocking and bridging in the inlet to the moulding chamber has been eliminated, at the same time as satisfactory filling and compaction of the moulding material are achieved in the moulding chamber.
According to the invention, this object is achieved by an apparatus of the type described in the opening paragraph characterized in that the moulding material is sucked into the moulding chamber through a slot placed centrally in the squeeze plate, and that the bottom of the container is tapered in V-shape in the direction of the slot in its entire longitudinal direction, whereby one or more air intake openings are provided on the tapered side faces of the container.
It has been found that the amount of air sucked in due to the vacuum in the moulding chamber generates an air cushion, which reduces friction in the inlet and "rinses" the oblique, tapered sides of the container. Providing one slot ensures maximum moulding material flow by time unit, as the moulding material will flow laminarly through the slot in the same way as in the case of unobstructed emptying from a bag-shaped orifice.
According to the invention, the slot may have a length and a width corresponding to the moulding chamber, ranging from 30 to 90 mm, preferably 55 mm.
Experiments have shown that particularly excellent filling is obtained when slot widths are kept within this interval, and a slot width of 55 mm is particularly advantageous.
In a perferred embodiment of an apparatus according to the invention, screen plates are placed above the air intake openings on the side faces placed opposite each other in the container bottom tapered in V-shape, while forming side slots some distance above the bottom slot.
By placing screen plates, the danger of blocking the intake openings is eliminated, and a slot is formed, so that the sucked-in air can be directionally led across the oblique container side faces, preferably towards the slot in the bottom of the container. The friction-reducing rinsing effect is increased by this measure.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be described in more detail below with reference to the drawing, whole single FIGURE gives an oblique schematic view of an apparatus designed according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The apparatus includes a container 1 for keeping the moulding material 2, preferably moulding sand.
In the embodiment shown in the drawing, the apparatus is used for simultaneous making of two matching mould parts in an upper and a lo
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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