The problem is solved, according to the invention, by the characteristics
claimed in Claim 1, in regard to metering the charge, hv those claimed in Claim 2 in regard to the general distribution of the sand and by those of Claim 5 in regard to the loosening up of the sand.
The directed distribution of sand to different regions of the moulding box is ensured by the double array of guiding blades at two levels, extending across each other perpendicularly, as claimed in Claim 3.
The invention makes it possible to make foundry sand moulds by the conveyor belt method and yet control the distribution of sand to the moulding box, by adjusting the guiding blades, to suit each different 3 Q 1 kind of Model individually.
Claim 7 describes the preparation of the sand during the filling of the moulding box. The sand is loosened and large lumps broken up, where still necessary. A screen or the like in the bottom of the sand aerator housing completes the loosening of the sand and the breaking up of clots.
The sand-metering container rests on a weighing device which automatically interrupts feed from the conveyor as soon as the correct weight of sand has been charged into the sand-metering container.
An example of the invention is shown in the drawings, in which:
Figure 1 is a side-view of a mould-making machine. The machine is shown at rest, with the filling device of the invention mounted in position.
Figure 2 shows the filling device drawn to a larger scale, with moulding sand in a moulding box above a positive model.
Figure 3 corresponds to Figure 2, but in this case the model is a negative one.
A press table 9 is lifted and lowered by a hydraulic piston 19. The press table 9 is equipped with a balance adjustor 14 to 17 and is thrust upwards by four supporting compression springs 11. Mounted on the press table 9 is a supporting table 8 for resiliently supporting a model carrier 1 for holding the model 2. In Figures 1 and 2 this is a positive model 2 whose middle portion is raised. The model shown in Figure 3, on the other hand, is a negative model 2a with raised edges. In both cases the model (2 or 2a) rests on a turntable device 3 which 4 brings the model 2, when desired, into engagement in the mould-making machine. When the model 2 has been brought into engagement in the mould- making machine it is situated under a moulding box 5, whicharrives on a roller comveyor 4. Above the moulding box 5 there is a sand frame 6 fixed to a support 7. The mould-making machine also has a pressram 27 which can be swung into engagement for compacting the sand mould in the moulding box 5.
And the machine has a model-changing device 32 for exchanging one kind of model for another. Above the press table 9, the supporting table 8 with its model 2, the moulding box 5 and the sand frame 6 there is the filling device fixed to the machine frame 31. The filling device consists of an upper portion, i.e. a sandmetering container 25 into which the moulding sand is poured by a belt conveyor 41 and, under the metering-container 25, a sand aerator housing 20 capable of charging sand by gravity down into the sand frame 6.
The sand-metering container 25 is internally conical, becoming wider near the bottom, to facilitate downwards movement of the sand. The lower mouth of the sand-metering container 25, through which sand flows down into the sand aerator housing 20, is obturated bv a slidevalve 26 which can be opened and closed. For weighing out the portions of sand, the sandmetering container 25 rests on a weighing device 42.
As shown in Figure 2, the sand-metering container 25 can, for example, pivot at one side on a pivot bearing 43, being supported at the other side by a one-point weighing device 42, with the help of a bracket 44 fixed to the sand-metering container 25. It should be observed that each different kind of model 2 requires a different charge of sand. When sufficient sand has been charged into the sand-metering container 25, the weighing device 42 interrupts the feed of sand from the belt conveyor 41 and the slide-valve 26 opens, allowing the charge of sand to fall downwards through the sand aerator housing 20 until the sand-metering container 25 is empty, a fac., which is detected by the weighing device 42. Responding to a signal from the weighing device 42 t r the slide-valve 26 then closes and a new charge of sand is filled into the sand-metering container.25 by the belt conveyor 41.
The sand aerator housing 20 situated under the sand-metering, container 25 has three functions. It provides a connecting channel between the sandmetering container 25 and the sand frame 6. It loosens up the sand once more to ensure that it is finely divided and without lumps. And it distributes the sand, usually unevenly, to different regions of the moulding box 5 to suit the different requirements of the different kinds of model (2, 2a).
The upper portion of the sand aerator housing 20 contains a system of):otating beater blades 21 which rotate on shafts 34 extending trans versely across the direction of flow of the sand. The rotting beater blades 21 are s.pac - ed close enough together to ensure that all lumps in the sand are broken up, only finely divided sand reaching the moulding box 5.
The lower portion of the sand aerator housing 20 contains, at two levels. 6 and b (Figure 3), two arrays of guiding blades 22 and 23.' Each guiding blade 20 is adjustable in angle by rotation on two pivot pins 40, one at each end of the blade 22, 23, the pivot pins 40 rotating in the wall of the sand aerator housing 20. At each level a and b the guiding blades 22, 23 rotate on axes parallel to each other, the axes of the upper blades 22 being perpendicular to the axes of the lower blades 23. In other words, the guiding blades 22, 23 criss-cross each other. By adjustment in angle of each blade individually it is possible toachieve any desired distribution of sand in the moulding box 5, for example more towards the outer edge or more towards the middle, to suit the individual requirements of each different kind of model.
To loosen the sand g.till better, and to prevent lumps from passing through into the moulding box 5, the bottom of the sand aerator housing 6 has a screen 24 or, if desired, a double system of parallel wires at two levels, the wires at the one level running crosswise across those at the other level. Arranging the wires at two levels, in the manner just described, effectively prevents the screen from becoming choked locally by accumulations of sand.
In practice, in spite of the good action of the rotating beater blades 21, there is still a tendency for the sand to clot or cake, both on the guiding blades 22, 23 and on the screen or crossed wires 24. This could be avoided, in principle, by vibrating these parts of tile machine, but that would involve extra costs and undesired complexity. An excellent alternative remedy has been found in heating various machine parts, particularly the guiding blades 22, 23, the screen or crossed wires 24 and the sand aerator housing 20 itself. In particular it has been found that heating effectively prevents the sand from caking on the guiding blades 22, 23.
The function of the guiding blades 22, 23 will now be described in greater detail with the help of Figures 2 and 3. As already mentioned, each individual guiding blade 22, 23 is adjustable in angle by rotation on the pivot pins 40. When a positive model 2 is being used, as represented in Figure 2, the guiding blades 22, 23 are adjusted to throw the sand more outwards towards the edges of the moulding box 5. Consequently, as indicated at 35, the upper surface of the sand in the moulding box 5 trough-shaped. Subsequently, when the sand is compacted, either by the hydraulic piston 19 or by the press ram 27, the sand near the edges of the moulding box 5 is compressed over a longer stroke than the sand near the middle. The final result is sand compacted to equal bulk density in all regions of the moulding box 5.
On the other hand, as shown in Figure 3, when a negative model 2 is being used, the surface 35 of the sand iTI the moulding box 5 should be hillshaped, higher near the middle. The guiding blades 22, 23 are 1 7 W 1 therefore adjusted in angle individually to throw the sand more towards the middle of the moulding box 5. After the sand has been compacted the result, as before, is an even distribution of bulk density in all regions of the moulding box 5.
It should further be observed that during charging of the sand into the moulding. box 5 the vibration produced by the resilient support system 8 to 13, with its springs 11 and 17 for the supporting table 8, also helps in compacting the sand.
The sand-filling device described above can be used either by itself or in combination with the sand-mevering container 25 and the sand aerator housing 20. Both the metering of the charge of sand and its directed distribution by the guiding blades 22, 23, to suit the, individual requirements of different models, can be fully automated. On the other hand, angular adjustment of the guiding blades 22, 23 can at any time be done by hand, if desired, from outside the machine.
8 1 -4 1 Patent Claims.
1. A filling device, particularly for filling sand (35) into the moulding box (5) of a mould-making machine in the automatic making of foundi-, sand-moulds, the filling device consisting of a sand-metering container (25) mounted over a sand aerator housing (20), characterised in that interposed between the sand-metering containei (25) and the sand aerator housing (20) there is a slide-valve (26) f-)i- Jlnici-iupting the flow of sand leaving the sand-metering container (2',) inii] it received the desired charge of sand.
1). Filling device as claimed in Claim 1, characterised in th;-j7 tll-if, upper portion of the sand aerator housing (20) contains (21, 34) for loosening the flowing sand, its lower portion containing devices 2 (22, 3, 40) for guiding the stream of sand flowing into the mnolding box (5).
1 3. Filling device as claimed in Claim 2, characterised in that the devices for guiding the stream of sand flowing into the moulding box (5) are pivoted guiding blades (22, 23), some situated at a higher level a, some at a lower level b, the blades (22, 23) at each level (a or b) extending parallel to each other and extending substantially all the eay across the sand aerator housing (20), the upper blades (22) extending in direction perpendicularly across the lower blades (23), the guiding angles of the blades (22, 23) being adjustable by rotation from outside the sand aerator housing (20).
9 J P Y 4. Filling device as claimed in Claim 5, characterised in that each guiding blade (22, 23) pivots with the help of two pivot pins (40), fixed one at each end to the blade (22, 23) and rotating in the wall of the sand aerator housing.(20), the pivot pins (40) being rotated, for adjusting the guiding angle of the blade (22,,23), by external control means so that the stream of sand reaching the moulding box (5) becomes distributed in a manner suited to the individual requirements of the different kinds of models (2).
5. Filling device as claimed in Claim 2, characterised in that the devices (21, 34) for loosening the flowing sand are rotating beater blades (21) mounted on shafts (34) extending transversely across the flowing stream of sand and intercepting the entire stream, the beater blades (21) being spaced close enough together to loosen up the entire stream of falling sand.
6. Filling device as claimed in one of the Claims 1 to 5, characterised in that at the bottom outlet of the sand aerator housing (20) there is a screen (24) or two layers of parallel screening wires, the one layer situated above the other, the wires of the one layer crossing those of the other layer perpendicularly.
7. Filling device as claimed in Claim 1, characterised in that the sandmetering container (25), which measures out the correct charge of sand for each individual mould-making operation, has an upper inlet opening, preferably under the delivery end:)f a belt conveyor (41)-or the like, the sand-metering container (25) being supported by a weighing device (42) which automatically interrupts the feed of sand from the belt conveyor (41) when the desired quantity of charge is reached and opens the slide-valve (26).
8. Filling device as claimed in Claim 7, characterised in that the sandmetering container (25) is pivoted at;,ie side, its other side e 10, resting, preferably by a one-point support (44), on the weighing device (42), such as an electronic sensor.
9. Filling device as claimed in one of the Claims 1 to 8, characterised in that fully automatic programmed control is provided for weighing out each charge of sand, for interrupting the feed from the conveyor and for adjusting the guiding angles of the guide-blades to suit the different kinds of model.
10. Filling device as claimed in one of the Claims 2 to 6, character ised in that a heating device is provided for heating the guiding blades (22, 23) and/or the screen (24) or the crossed screening wires of the sand aerator housing (20).
Filling device as claimed in one of the Claims 2 to 7 or characterised in that the interior of the sand aerator housing (20) is he at ed.
12. A device for filling sand moulds substantially as hereinbefore described with reference to the accompanying drawings.
Publi"ed 1988 IL 7ne P&-er- 0MCe. SLWL4, Ho,,:,Se 66'71 liig! Ho'born. London WOIR 4TF PurLher copies mky be ob;ainedd frorn The Patent =ce. Saaes Bramch. S' Iwry Cray, Orpingion. Kent BR5 3RD PrInted by Multiplex techniques Itd. St Marv Cray. Kent Con. 1/87 1 1 7