EP0497650A1 - Installation of and method for producing foundry moulds with granulated material - Google Patents

Abstract

The invention concerns a device and method for continuous fabricating of foundry molds from granular material. The device consists of a frame (10) with lights (11) supporting through swivels (31) caissons (30, 40) with large partitions (42) provided with grooves (421) into which pattern-plates (60) are inserted, and with small partitions (43) provided with suction holes (431); the caissons being connected to a vacuum source through flexible hoses controlled by solenoid valves; the whole assembly being placed after heat-forming of a polymer film (92) around a grid (70) with a hollow rib (74) and filter (741) connected to a vacuum source through a connector (75).

Description

The present invention relates to a device and a method for continuously manufacturing foundry molds of granular material.

French patent application No. 2,307,596 describes a frame of foundry molds, in which there is provided a means for introducing and recovering the granular material used. This means consists of a volume of substantially frustoconical shape, the small base of which is provided with a hatch through which the filling tube can be introduced; this hatch is airtight and remains closed throughout the period of use of the chassis. After molding, the vacuum is broken, the chassis being turned over, and the hatch opens, letting the material flow by gravity.

Such a device and such a method confer, on molding, only slow rates, because it is necessary to carry out numerous handling operations. Furthermore, the casting is carried out with the mold held in the assembly of the two chassis, which immobilizes two expensive chassis for obtaining a single mold. Similarly, it is necessary to carry out the shaping operation twice to obtain the upper and lower parts of the mold, this double operation leading to obtaining a complete mold.

A device and a method are already known which make it possible to overcome, in part, these drawbacks, such as those described in French patent application No. 87 10514. The device in question is distinguished from the similar ones by the fact that it consists of at least two model plates, placed in the corresponding housings of a support, and at least one sealing plate and a frame comprising two faces. The model plate support elements and the sealing plates are hinged together. The polymer sheet is unique and corresponds to the surface of the sealing plates and the model plates.

The process essentially consists of preparing the model plates in the support, placing on them a polymeric envelope by thermoforming and aspiration through the plates, placing the model plates around of a reinforcement comprising, at most, three faces, to ensure the seal between the polymer envelope and the reinforcement, by clamping the film between reinforcement and plates, or by plating thereof on the reinforcement by inflation d '' a joint, to ensure the filling with granular material, to assemble, by welding, the ends of said envelope, over the upper frame, to evacuate the space delimited by the polymer envelope through of the frame, to remove the plates and to assemble the clods thus obtained, for the creation of imprints.

This process and this device make it possible to obtain movements with reduced handling. In addition, only the reinforcement and the polymer envelope are used at the casting station and the reinforcement is much simpler than the chassis used previously, hence a fairly reduced investment. In addition, a single operation makes it possible to obtain the two parts of a mold, which therefore improves the yield by almost 50%. The process is semi-continuous, but the casting can be continuous, by juxtaposing the lumps. The number of parts required is reduced, as is the volume of granular material used.

However, the use of a two-sided frame hardly lends itself to handling on rollers and the importance of the strokes and of the masses to move limits the performances.
The device and the method according to the invention aim to remedy these drawbacks by proposing a support for model plates with sliding and pivoting boxes, connected to a vacuum source, capable of pressing against the frame, after interposition of a polymer film, with plating, in superposition, of the upper ends thereof against the top of the frame, under the effect of pressure and vacuum.

The device according to the invention is characterized mainly by the fact that the support for model plates consists mainly of two boxes, with two compartments, each connected to a vacuum source capable of sliding and pivoting. 'towards each other, relative to a frame surrounding a vibrating table on which is placed a three-sided frame, connected to the vacuum source.

The large compartment of each box is made to the dimensions of a model plate, which ensures closing by embedding in a rebate provided for this purpose in the edge of the opening of said box.

The small compartment of each box is completely closed and has, in its wall located in the extension of the model plate, air passage holes.

The width of the small compartment is determined according to that of the frame and corresponds to approximately 2/3 of it.

The boxes slide and pivot by means of two pins, arranged laterally in the median plane of each box, and of lights, forming slides, arranged at the upper part of the frame.

The frame is formed of the three faces of a rectangular parallelogram, the upper face of which is absent, the vertical faces of which, connected by a hollow central rib covered with a microperforated filter, each comprise, in addition to a filtering device, a mouthpiece vacuum, equipped with a non-return valve, a handling pin, a support shoe, for clamping on the vibrating table, and a machined surface, intended to serve as a geometric reference for the molded parts.

• mettre les caissons en position horizontale,
• encastrer une plaque-modèle dans chacune des feuillures des grands compartiments de chaque caisson,
• thermoformer, sur chaque plaque-modèle, un film en matière plastique, débordant par dessus chaque petit compartiment des caissons,
• mettre les deux compartiments de chaque caisson en communication avec la source de vide, par action sur les électrovannes,
• pulvériser, éventuellement, sur la surface de chaque film, un produit anti-adhérent,
• disposer l'armature sur la table vibrante, après avoir écarté, puis fait pivoter les caissons en position verticale,
• plaquer les plaques-modèles contre l'armature, par coulissement des tourillons dans les fenêtres, formant glissières, du bâti,
• solidariser les caissons à la table vibrante, soit directement, soit grâce à un bâti intermédiaire,
• remplir, avec un matériau granulaire, l'espace laissé libre entre les deux plaques-modèles, la table vibrante étant en action,
• mettre le petit compartiment de chaque caisson à la pression atmosphérique, par action sur les électrovannes,
• replier chacune des extrémités du film plastique, qui recouvrait chaque petit compartiment du caisson, contre le dessus de la motte de sable,
• mettre la nervure creuse de l'armature en communication avec la source de vide, pour obtenir la rigidification de la motte,
• couper le vide dans les grands compartiments des caissons par l'intermédiaire des électrovannes correspondantes et reculer ceux-ci afin de libérer l'armature,
• évacuer la motte vers la ligne de coulée, en maintenant l'armature sous dépression,
• ramener les caissons en position horizontale pour un nouveau cycle d'opération.

The method of implementing the device according to the invention is characterized, mainly, in that it consists, after having placed the frame around the vibrating table, at:

• put the boxes in a horizontal position,
• embed a model plate in each of the rebates of the large compartments of each box,
• thermoform, on each model plate, a plastic film, overflowing over each small compartment of the boxes,
• put the two compartments of each box in communication with the vacuum source, by acting on the solenoid valves,
• spray, if necessary, on the surface of each film, a non-stick product,
• place the frame on the vibrating table, after having removed it, then rotate the boxes in a vertical position,
• press the model plates against the frame, by sliding the pins in the windows, forming slides, of the frame,
• secure the boxes to the vibrating table, either directly or through an intermediate frame,
• fill, with a granular material, the space left free between the two model plates, the vibrating table being in action,
• put the small compartment of each box at atmospheric pressure, by action on the solenoid valves,
• fold each end of the plastic film, which covered each small compartment of the box, against the top of the clod of sand,
• putting the hollow rib of the armature in communication with the vacuum source, in order to stiffen the root ball,
• cut the vacuum in the large compartments of the boxes through the corresponding solenoid valves and move them back in order to release the armature,
• evacuate the root ball towards the casting line, keeping the reinforcement under vacuum,
• return the boxes to a horizontal position for a new operating cycle.

The advantages obtained thanks to this invention consist, essentially, in that, thanks to the reduction of the strokes and of the masses in movement, the performances are improved. The presence of a bottom face on the frame also facilitates a certain number of handling operations.

• la figure 1 représente le dispositif en position initiale, film plastique en place,
• la figure 2 représente la seconde étape du procédé, correspondant au basculement, à la verticale, des plaques-modèles et à la mise en place de l'armature,
• la figure 3 représente la troisième étape du procédé, correspondant au rapprochement des plaques-modèles et au repliage de l'extrémité du film,
• la figure 4 représente la quatrième étape du procédé, correspondant à la libération de l'armature, par recul des plaques-modèles, après constitution de la motte,
• la figure 5 représente une vue en perspective de l'armature.

Other characteristics and advantages will appear in the following description of the device implemented according to the method of the invention, given by way of nonlimiting example with regard to the appended drawings in which:

• FIG. 1 represents the device in the initial position, plastic film in place,
• FIG. 2 represents the second step of the method, corresponding to the tilting, vertically, of the model plates and to the positioning of the frame,
• FIG. 3 represents the third step of the process, corresponding to the approximation of the model plates and to the folding of the end of the film,
• FIG. 4 represents the fourth step of the method, corresponding to the release of the frame, by retraction of the model plates, after constitution of the root ball,
• Figure 5 shows a perspective view of the frame.

The figures represent a device for continuously manufacturing foundry molds in granular material, according to the invention, comprising a frame 10 with lights 11 , supporting, by means of pins 31 , 41 , boxes 30 and 40 at large compartments 32 , 42 with rebates 321 , 421 , in which the model plates 50 , 60 fit, and with small compartments 33 , 43 with suction orifices 331 , 431 ; said boxes being connected to a vacuum source, respectively, by flexible pipes 322 , 422 and 332 , 432 central, by solenoid valves 323 , 423 , 333 , 433 ; the assembly being arranged around a frame 70 with sides 71 , 72 , 73 , connected by a hollow rib 74 with a microperforated filter 741 , placed in communication with the vacuum source by means of a nozzle 75 , provided with trunnions handling 76 , support shoes 77 and a machined surface 78 .

By examining Figures 1 to 4 in more detail, it can be seen that the placing in position of the boxes 30 and 40 allows easy embedding of the model plates 50 and 60 in the rebates 321 and 421 of the large compartments 32 and 42 and a setting easy placement of a polymer film 91 , 92 on the model plates and on the small compartments 33 and 43 , using the vacuum exerted in all of the compartments by means of the flexible pipes 322 , 422, 332 , 432 , by action on the solenoid valves 323 , 423 , 333 , 433 . The spraying of a product on the surface of the polymer film, followed by rapid drying, is all the more facilitated by this horizontal presentation.

The existence of pins 31 and 41 on the sides of the boxes 30 and 40 and the introduction of these into the slots 11 of the frame 10 allow, as shown in FIGS. 2 to 4, easy tilting and sliding of the boxes 30 and 40 supporting the model plates 50 and 60 , which allow their approximation or their spacing relative to the frame 70 resting, by its base 73 , on the vibrating table 80 .

By examining more particularly FIG. 3, it is noted that, subject to having previously broken the vacuum in the small compartments 33 and 43 of the boxes, the ends 911 and 921 of the polymer films can be folded over the upper part 101 of the clod 100 made of granular material, with superimposition of the edges before application of the vacuum in the hollow rib 74 of the frame by means of the end pieces 75 , and after the vibrating table has been put into operation, following the filling of the gap between model plates with granular material.

Claims (7)

Device for the manufacture of foundry molds, in particular of granular material, comprising model plates, sealing plates, a frame, at least one polymer envelope, a means of supplying granulated material, and means of placing under void consisting of at least two model plates, placed in the housings of a support, the frame comprising, at most, three faces, characterized in that the support of model plates ( 50, 60 ) consists mainly , two boxes ( 30, 40 ) with two compartments ( 32, 42 and 33, 43) each connected to a vacuum source, capable of sliding and pivoting towards each other, relative to a frame ( 10 ) surrounding a vibrating table ( 80 ) on which is placed a frame ( 70 ) with three faces ( 71, 72, 73 ), connected to the vacuum source. Device according to claim 1, characterized in that the large compartment ( 32, 42 ) of each box ( 30, 40 ) is made to the dimensions of a model plate ( 50, 60 ), which ensures the closing thereof by embedding in a rebate ( 321, 421 ) provided for this purpose in the edge of the opening of said compartment ( 32, 42 ). Device according to claim 1, characterized in that the small compartment ( 33, 43 ) of each box ( 30, 40 ) is completely closed and comprises, in its wall located in the extension of the model plate, through holes d 'air ( 331, 431 ). Device according to claim 3, characterized in that the width of the small compartment ( 33, 43 ) of each box ( 30, 40 ) corresponds, approximately, to 2/3 of the width of the frame ( 70 ). Device according to claim 1, characterized in that the boxes ( 30, 40 ) slide and pivot by means of two pins ( 31, 41 ), arranged laterally in the median plane of each box ( 30, 40 ), and of lights ( 11 ) horizontal, forming slides, arranged at the upper part of the frame ( 10 ). Device according to claim 1, characterized in that the armature is formed of the three faces ( 71, 72, 73 ) of a rectangular parallelogram, the upper face of which is absent, the vertical faces ( 71, 72 ) of which are connected by a hollow central rib ( 74 ) covered with a microperforated filter ( 741 ), each comprises, in addition to a filtering device, a nozzle ( 75 ) for evacuation provided with a non-return valve, a handling pin ( 76 ), a support shoe ( 77 ) for clamping on the vibrating table, and a machined surface ( 78 ), intended to serve as a geometric reference for the molded parts. Method for using the device according to Claims 1 to 6, characterized in that it consists mainly, after having placed the frame ( 10 ) around the vibrating table ( 80 ), at: - put the boxes in a horizontal position, - insert a model plate ( 50, 60 ) in each of the rebates ( 321, 421 ) of the large compartments of each box ( 30, 40 ), - thermoform, on each model plate ( 50, 60 ), a plastic film ( 91, 92 ), projecting over each small compartment ( 33, 43 ), - put the two compartments of each box in communication with the vacuum source, by acting on the solenoid valves ( 323, 423, 333, 433 ), - spraying, if necessary, on the surface of each film ( 91, 92 ), a non-stick product, - place the frame ( 70 ) on the vibrating table ( 80 ), after having moved away, then makes the boxes pivot in a vertical position, - press the model plates against the frame, by sliding the pins ( 31, 41 ) of the boxes ( 30, 40 ) in the openings of the frame ( 10 ), - securing the boxes ( 30, 40 ) to the vibrating table ( 80 ), either directly, or by means of an intermediate frame (not shown), - fill, with a granular material, the space left free between the two model plates ( 50, 60 ), the vibrating table being in action, - put the small compartments ( 33, 43 ) of each box ( 30, 40 ) at atmospheric pressure, by action on the solenoid valves ( 333, 433 ), - fold each end of the plastic film, which covered each small compartment of the box, against the top of the clod of sand, - putting the hollow rib ( 74 ) of the armature in communication with the vacuum source, in order to stiffen the root ball, - cut the vacuum in the large compartments ( 32, 42 ) of the boxes ( 30, 40 ) by means of the corresponding solenoid valves ( 323, 423 ) and move them back, in order to release the armature, - evacuate the root ball towards the casting line, keeping the armature under vacuum, - return the boxes ( 30, 40 ) to a horizontal position for a new operating cycle.

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