DE3124024A1 - METHOD AND DEVICE FOR PRODUCING MOLDING MASKS - Google Patents

Abstract

1. A method of preparing a shell mould - for foundry use - from a thermally hardenable moulding sand by forming it on a heatable pattern (1) the shaped surface of which is turned downwardly, characterized in that the pattern (1) is heated, until the shell mould has been formed, in a mass of sand (7) fluidized by a rising air stream, that while the shell ist being formed air is fed under pressure through a base plate (11) into an enclosed space, and in that the air egress form the enclosed space through a pattern plate (2) carrying the pattern (1).

Description

Method and device for the production of shaped masks

The invention relates to a method of manufacture of molding masks for foundry applications from a thermally hardening molding sand on a heatable model and a device for carrying out the method. It refers to all types of sand suitable for this, the appropriate binding agent, e.g. in the form of a coating of the individual grains of sand or a have moisture-binding admixture to the sand.

The production of molded masks with thermally hardening molding sand according to the so-called Croning process is generally known. The methods used so far have disadvantages with regard to the ¹ liberation of the finished model from the non-hardened molding sand and from the point of view of the unsatisfactory management of pollutants arising during the hardening. Furthermore, the great procedural and structural effort is felt to be disadvantageous.

The invention is based on the task of simplifying and accelerating the production process and furthermore to offer suitable measures for the removal of the pollutants. This should also include the use be possible or guaranteed in a higher-level production process.

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The main task is solved by that the model with the mold surface facing down in a volume of sand fluidized by an increasing air flow until a Form mask is heated. Much more contributes to the solution that during the mask formation from the interior air is discharged via a model plate supporting the model. A device suitable for this procedure has a fluid container with a bottom piston with air supply openings and one that closes the fluid container removable model plate with air outlets.

The suspended arrangement of the model in a fluidized sand volume allows _s withdraw the finished shape of the mask with the model up while the excess, not hardened molding sand remains in its position, particularly in a fluid container. The thickness and strength of the formed mask can be adjusted in the usual way through the model temperature and the curing time and, moreover, according to the invention through the density of the fluidized sand, which can be regulated as a function of the air flow.

A special possibility of influencing the mask formation arises when a model plate carrying the model or a bottom piston in a fluid container. be brought closer together during masking, in particular by lifting the bottom piston. The lowering the model plate and lifting the bottom piston

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is technically equivalent. When the bottom piston can be raised, the model plate can then are carried out in a particularly simple manner in the form of a lid on the fluid container.

The sand is fluidized by blowing air into the bottom area of a fluid container or Another device, in particular through openings in the bottom piston, the air through openings in the model plate, especially in the vicinity of the model through openings more appropriate Size can escape. Depending on the shape of the model, it is also advantageous to use the model area itself There should be discharge or suction openings in order to accelerate or improve the mask formation. The air is normally supplied during removal of the preformed mask and refilling of the processed sand continuously.

An embodiment that is particularly suitable for solving the problem is one that can be connected to the container in a sealing manner Model plate in front of which the pollutants emerge collected at a single suction opening can. In the same way, the bottom piston is preferably designed with a compressed air connection opening. Instead of a multitude of small openings in the bottom flask, which is endangered by sand clogging is, according to the invention, a .Bodenkolben from a preferable to air-permeable sintered material.

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The sand can be refilled with the lid lifted in the usual way by refilling from above or in a preferred automatic way through Slipping over the lateral filler neck in the fluid container take place. The dump height is automatically determined by the height of the inlet openings in combination with a lowering of the piston. The sand in the fluid container usually remains in fluidized state. The filler necks come with a higher sand reservoir connected via lines that drop steadily from this. '

According to the invention, a cooling channel in the fluid container in the upper area prevents a heat transfer from the heated one Model and the model plate on the fluid container, so that a hardening of the inside Sand is excluded.

The figure shows an embodiment of a device according to the invention.

A model 1 is attached to a model plate 2 with the mold surface facing downward, which as Has slot nozzles formed air outlet openings 3 in the vicinity of the model. The model plate 2 is a Air suction box 15 with a suction nozzle 16 attached. The model plate 2 serves as a removable, ins-

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special hinged lid of a fl \ ri.dbchnlter :: · 1Π, which has a cooling channel 4 in the upper area. Below the model is the one shown Situation before the start of the mask formation a free space 5. The fluidized sand volume is 7. automatic; up to the height of filler necks arranged on both sides increased. The filler neck 6 are connected to a sand reservoir, not shown falling channels connected. The height-mobile, with a plurality of air supply openings 17 provided bottom piston 11 is opposite the fluid container .10 sealed by a sealing lip 12. An overpressure box 9 is built under the bottom piston 11, which with this forms a pressure space 8 and is supplied via a flexible pressure line 14. The bottom piston 11 with the overpressure box 9 is movable in height by means of an adjusting device 13 not detailed, so that the fluidized sand in the desired manner to the extent constant or periodic to the model can be moved so that a density and curing-controlled molded mask is created.

L e r s e it e

Claims (16)

/ JL \ C \ Π / IiLl) 5OQp, JoSjLn. 8Q »- May -1.5.Q6.1981 Nöu / Ro D 81/29 Process and device for the production of form facings 1. Process for the production of molds for foundry applications from a thermosetting material Molding sand on a heated model, characterized in that the model (1) with the mold surface facing downwards in one through a increasing air flow fluidized sand volumes (7) is heated until a molded mask is formed. 2. The method according to claim 1, characterized in that before the mask formation, an interior space under the model (1) while maintaining a Free space (5) is poured up with sand and that during the mask formation the interior space is approached; its bottom piston (11) and the model plate (2) is reduced to one another. 3. The method according to any one of claims 1 or 2, characterized in that the dump height in the interior is regulated automatically by the entry height (6) of a sliding higher sand column. 20000 0.73 pg - _{F350 / i} L * A / üiLj - 2 -: · ..:. - :: ··. . '. · - [ "· D 81 / 2-9 3124024 - · -: .- ■ ·. · ..-". "·····.: · 15.06.81 4. The method according to any one of claims 1 to 3 _f, characterized in that the sand volume (7) in the interior is fluidized during · the filling up or automatic sliding down from the higher sand column. 5. The method according to any one of claims 1 to 4, characterized in that at least during the Mask formation the interior air is supplied with excess pressure via its bottom piston (11). 6. The method according to any one of claims 1 to 5> characterized in that during the formation of the mask from the interior air over a bearing the model Model plate (2) 'is removed. 7 device for performing the method according to one of claims 1 to 6, characterized by a fluid container (10) with a bottom, .with air supply openings (17) and a model plate (2) that closes off the fluid container (10) and has air outlet openings, which can be lifted off (3). 8. Apparatus according to claim 7, characterized by one within the fluid container (10) high movable bottom piston (11). KlOOO 6.73 pn. · F3C0 / 1 AAL · AuULJ "~ 3 -.- I. * '.. *.. *". "". . ". D 81 / Device according to one of Claims 7 or 8 _9, characterized by a model plate (?.) That is adjustable in height within the fluid container (10). 10. Device according to one of 'claims 7 or 8, characterized by a hinged model plate (?.) Hinged on the fluid container (10), 11 .. device according to one of claims 7 to 10, characterized by a bottom piston (11) made of air-permeable sintered material. 12. Device according to one of claims 7 to 11, characterized by one of the bottom piston (11) built underneath Overpressure box (8). 13. Device according to one of claims 7 to 12, characterized by one of the model plate (2) placed thereon Air suction box (15). 14. Device according to one of claims 7 to 13, characterized by at least one attached in the bed height lateral filler neck (6) in the fluid container (10). . 15. Device according to one of claims 7 to 14, characterized by one arranged above the filler neck (6) and connected to the latter by falling channels Sand storage tank. SOOOO 0.79 PU i ^: 2S0 / l Ac 16. Device according to one of claims 7 Ms 15, characterized by one at the level of the model plate
(2) arranged cooling channel (4) on the fluid container (10). COO 9.79 DJ 'F3S0 / 1