EP0218496A2 - Machine for manufacturing foundry cores - Google Patents

Abstract

The invention relates to improvements made to core cleaning machines which are essentially characterised in that they consist of the arrangement of a pair of horizontal slideways intended to be located so as to correspond with the transverse and mid- planes of the machine, provision having been made for a pair of cars, adjacent in the lateral direction, carrying corresponding core boxes, to be located on the slideways such that, in a precise position of the cars relative to the slideways, one of them is opposite the working zone of the machine whilst the other car remains laterally offset, permitting replacement of the core box which has already been used by another new one. <IMAGE>

Description

The present invention relates, as explained in this specification, to a series of improvements in machines for cleaning foundry cores by sand blasting, improvements affecting, in particular, the means for automatic change of core boxes, the projection mechanism, and a special device for removing the remains of sand that have remained on the projection plate.

It is well known that these machines require frequent tooling changes, which results in significant operating complexity. Thus, it is very desirable to be able to automate this operation.

Thus, one of the objectives of the invention consists in solving this problem by allowing the change of cases to be accomplished in automatic form and without this operation causing a stop of the operation of the machine, that is to say that is, while the change of one of the crates takes place, the machine can continue to clean the cores of another.

In accordance with these objectives, the installation proposed by the invention consists of two horizontal and lower slides where three sectors can be defined, one of which intermediate facing the machine operating area and the other two lateral and emerging of the machine base plate by obviously opposite areas.

Two carriages joined together, in an adjacent situation, move on these slides with a possibility of reciprocating movement, so that these carriages will always occupy the intermediate sector and one of the lateral sectors of these slides; in one of the positions, it is one of the carriages which occupies the intermediate sector of the slides, while, in the other extreme position, it is the other carriage which occupies it.

This is how we manage to place one of the carriages facing the machine operating area while placing the other in a change situation for the corresponding core box.

Obviously, this means that, when one of the core boxes is being replaced, there is another in working condition, and, therefore, the change operation is accomplished without appreciable downtime, from operational point of view for the machine.

In addition, and in order to automate this change operation, each of the above carriages has at its upper part two other slides, perpendicular to the previous ones, for the movement of respective complementary and upper carriages acting as extractor-box introducers while the first, that is to say, the lower ones, act to substitute the same for the working area of the machine.

Obviously, it is these upper carriages which receive the corresponding firing plates, expulsion plate and core box and all the tools.

As a complement to the above structure, the lower carriages, joined together as indicated above and provided with wheels for their sliding on their slides, are, moreover, secured to the ends of a chain closed on itself using end sprockets and driven by a geared motor controlled for this purpose, establishing the two specific provisions d 'stop of the carriages relative to the machine frame.

A similar arrangement allows the movement of each upper carriage relative to the corresponding lower carriage to be controlled.

From what has just been explained and as this results, when the machine operates on a pair of stacked carriages, the other pair is laterally offset from the base plate of the machine and in such a way that the upper carriage of this pair of carriages moves in order to replace the core box already treated, by a different case or tool and, after that, the upper carriage in question will move to another extreme position relative to the lower one, position where the two carriages, duly superimposed, will be in conditions of moving together to replace those presently in operation within the machine.

In accordance with another of the characteristics of the invention, the projection mechanism being intended to provide, at a certain moment, the air pressure necessary to cause the emptying of a cartridge at practically constant flow, that is to say say without a significant loss of pressure between the moment of opening and the end of the operation, uses the fluid stored in a reservoir, establishing between this reservoir and the cartridge by a large diameter pipe a rapid discharge of fluid without losses dump.

It is obvious that the cartridge must be replaced after each projection and, for this purpose, the projection mechanism itself is in able to lengthen and shorten telescopically in order to establish a tight coupling on the mouth of the cartridge prior to projection, or to separate from it, after the latter, in order to replace the cartridge.

For this purpose and more specifically, the mechanism proposed by the invention is formed from a hollow endpiece, open in the zone of the perimeter of its lower base in correspondence with the mouth of the cartridge and provided with annular seals of sealing to ensure hermetic coupling between nozzle and cartridge, its upper base extending axially into a hollow body constituting the supply conduit of the nozzle; this hollow body having internally and telescopically playing therein a second also hollow body, emerging from its upper end and to which is assembled the projection control valve through which communication is established, during projection, between the pipe formed by these two body and container.

The projection valve comprises a large diameter piston, in an axial arrangement and receiving the network pressure also axially, so that the latter tends to keep the piston closed on the mouth of the two hollow bodies relative to the nozzle, while the reservoir remains in communication with the valve through a conduit also of large diameter, the piston playing in an annular skirt of the valve body defining a conduit with the above reservoir.

In accordance with the structure summarized above, when the network pressure arriving directly at the projection valve is interrupted, the pressure in the reservoir causes the piston to move in the opening direction, and the charge of the pressurized fluid contained in the tank arrives at high flow rate in the hollow and telescopic tubes to reach, through the opening of the nozzle, the upper zone of the cartridge, which therefore causes the instantaneous emptying of the latter.

As has been reported, it is necessary, prior to the actual spraying operation, that the nozzle is hermetically assembled on the mouth of the cartridge, therefore having to move axially on the latter. In this sense, it is provided that the two hollow bodies are surrounded by a nozzle cylinder defining a chamber between the lower or enveloping hollow body and the nozzle cylinder, chamber being compartmentalized by means of a ring integral with the hollow body and having two fluid inlets at its ends, one upper and the other lower, so that the supply of fluid through the upper inlet causes pressure in the upper sub-chamber which, in turn, causes the tip to move in the upward direction, while pressure applied through the lower inlet causes an opposite effect.

Finally and as a complement to the above structure, it can also be indicated that the nozzle has a lateral outlet provided with a valve which remains closed until the end of the projection phase and which, opens in synchronism with the projection valve, when it closes, which causes rapid exhaust via a silencer.

Obviously, the fluid inlets to the end cylinder as well as the network pressure inlet to the projection valve are controlled by respective solenoid valves allowing full automation of the core cleaning machine.

Another characteristic of the invention, as indicated above, relates to a device for removing the rest of the sand remaining on the projection plate at the end of each operation.

It is well known that in core cleaning machines by means of a cartridge containing sand, and by means of the supply of a strong jet of pressurized air, the propulsion of sand is brought about on a core box, whether vertical or horizontal, the core box having been previously placed on a projection plate, fitted on a carriage allowing lateral movements of the latter in order to facilitate the positioning of the box and the subsequent arrangement thereof facing the bell through which the impulse of the sand takes place.

In practice, therefore, there remains a certain amount of residual sand which is deposited on the projection plate and which obviously requires cleaning of the latter each time the core box is replaced, and at the end of the working day. .

The device of the proposed invention has therefore been specially studied with a view to carrying out this cleaning operation in a safe, efficient and fully automated manner.

For this purpose, this cleaner consists of a platform arranged laterally relative to the chassis of the machine, platform to which the projection plate can be moved to carry out the cleaning operation.

By specifying further, this platform can be moved vertically using a cylinder, to rise and accommodate the projection plate and comprising lateral claws for fixing this plate actuated hydraulically by means of corresponding cylinders controlling these claws and the respective supports emerging below the platform.

As soon as the plate is immobilized, its cleaning is obtained by means of a sudden lateral tilting of the plate and, for this purpose, the plate proper form rests on a support provided with a tilting axis, lateral and external, and with an adjustable stop in situation opposite to this tilting axis, platform which extends beyond the tilting axis by a connecting rod controlled by a hydraulic cylinder fitted on the support and able to tilt on the latter.

Thus, after placing the projection plate on the tilting platform and fixing it by means of the associated side claws on this platform, the drive of the hydraulic cylinder, in association with the connecting rod, produces a tilting of the platform from its original horizontal position to a substantially vertical position, in a sudden movement in which the projection plate obviously accompanies the platform on which it is secured and, therefore, the sand residues on the plate are driven out.

This is how it is obtained, as has been sought for a rapid, effective and automated cleaning of the plate.

• - la figure 1 montre une représentation schématique en élévation latérale de la paire de chariots correspondant à l'installation de changement automatique de caisses dans une machine de nettoyage de noyaux selon la présente invention.
• - la figure 2 montre une vue en plan du même ensemble de la figure 1.
• - la figure 3 montre, selon une représentation semblable à celle de la figure 1, l'un des chariots y apparaissant avec la caisse à noyaux correspondante ainsi que ses mécanismes d'entrainement.
• - la figure 4 montre une vue en élévation frontale du même ensemble représenté en figure 3.
• - la figure 5 montre une représentation schématique en élévation latérale d'une machine de nettoyage de noyaux pourvue du mécanisme de projection constituant une autre des caractéristiques de l'invention.
• - la figure 6 montre un détail agrandi en élévation frontale et en coupe du mécanisme de projection.
• - la figure 7 montre, sur la même machine de nettoyage de noyaux, le dispositif nettoyeur de résidus de sable composant un autre des objectifs de l'invention.
• - la figure 8 montre une vue en élévation du dispositif nettoyeur de la figure précédente, à une échelle supérieure, où en ligne continue et en ligne de traits apparaissent les deux positions extrêmes de sa plate-forme basculante.

In addition to this description and for the purpose of an easier understanding of the nonlimiting characteristics of the invention, there is attached a set of drawings among which,

• - Figure 1 shows a schematic representation in side elevation of the pair of carriages corresponding to the installation of automatic case change in a core cleaning machine according to the present invention.
• - Figure 2 shows a plan view of the same assembly of Figure 1.
• - Figure 3 shows, according to a representation similar to that of Figure 1, one of the carriages appearing there with the corresponding core box as well as its drive mechanisms.
• - Figure 4 shows a front elevation view of the same assembly shown in Figure 3.
• - Figure 5 shows a schematic representation in side elevation of a core cleaning machine provided with the projection mechanism constituting another of the characteristics of the invention.
• - Figure 6 shows an enlarged detail in front elevation and in section of the projection mechanism.
• - Figure 7 shows, on the same core cleaning machine, the sand residue cleaning device constituting another of the objectives of the invention.
• - Figure 8 shows an elevational view of the cleaning device of the previous figure, on a larger scale, where in continuous line and line of lines appear the two extreme positions of its tilting platform.

As shown in Figures 1 to 4, the installation for automatic change of boxes is made from a pair of longitudinal rails 1, resting on multiple supports 2 and located within the base plate of the machine in correspondence with its transverse and mean axis, that is to say that these slides cross the working area of the machine and their middle faces it while their end portions project on both sides of the base plate. On these slides are located the carriages 3 and 4 provided with wheels 5 advantageously having a hollow V-shaped section of rectangular prismatic section with complementary vertical diagonal, for their support and perfect lateral centering on the slides of the slide section.

The length of these carriages is approximately one third of the length of the slides, so that, as shown in FIGS. 1 and 2, one of these carriages always occupies the middle sector of the slides while the other, in one of the positions the carriage 3 and in the other the carriage 4, occupies the extreme sectors of the slides.

The two carriages 3 and 4 are secured to each other by means of a spacer 6, while remaining secured to the ends of a chain 5 closing in on itself using extreme toothed wheels 8 and 9, the motor having reducer 10 driving this chain and the carriages 3 and 4.

The carriages 3 and 4 have a U-shaped configuration, with vertical branches, and on the ends of their free branches are placed two pairs of slides 11 and 12 similar to the lower slides 1 but in transverse arrangement relative to the latter.

These slides 11 and 12 are intended to receive, with the possibility of transverse displacement, two boxes with cores 13, as shown in FIGS. 3 and 4, boxes for this purpose comprising wheels 14 similar to the wheels 5 of the lower carriages, and carrying plates projection 15.

As in the previous case and occupying the empty space defined inside the lower carriages, each core box 13 comprises a gear motor 10 'driving a toothed wheel 16 which, as well as a second toothed wheel 17, receive a traction chain 18 on which by means of an appendage 19, is driven a pad 20 for moving the core box 13, connected by the fastener 21, the pad 20 sliding on slides 22 using four pairs wheels 23, as shown in detail in FIG. 4.

So therefore and starting from the situation shown in Figure 1, where each lower carriage 3-4 receives the corresponding core box 13, the platform 15 corresponding to the core box 13 arranged on the lower carriage 4 will be in working condition, while the assembly corresponding to the carriage 3 will remain in inoperative position, laterally offset from the working area of the machine, and in replacement conditions for the core box having been previously used. The action of the reducer motor 10 'provides the displacement to the right of the core box 13, as shown in FIG. 4. As soon as this replacement on this pair of superposed elements in an inoperative situation is accomplished, the reducer motor 10 'enters into operation in the opposite direction so that the assembly returns to the situation shown in Figure 4, the machine remaining in a position to replace the body at the end of the working phase in which it is then.

At the end of this working phase and the two double carriages still in the situation shown in Figures 1 and 2, the lower carriages 3 and 4 are moved to the right, so that the carriage 4 passes from the middle sector of the slides 1 to the extreme right sector, leaving the working area of the machine. At the same time, the carriage 3 occupies the previous position of the carriage 4, that is to say the middle sector of the slides, position of the working area of the machine and this in a minimum instantaneous period. After this replacement, the carriage 4 is then in a situation proper for the old core box, already used, to be replaced by another new box, all under normal operating conditions for the machine.

On the other hand and considering Figures 5 and 6, it can be seen that the projection mechanism which is the subject of another of the characteristics ticks of the invention, is composed from a fitting 101 intended to come into correspondence with the upper mouth of the cartridge 102 which, in turn, rests on the corresponding bell 103 of sand projection, this fitting being susceptible in addition to retracting, that is to say deviating in the upward direction of the cartridge in order to allow the replacement thereof after each projection.

The connector 101 also operates as a means for channeling the pressurized fluid coming to the cartridge 102 and, for this purpose, it is hollow and has two opposite openings 104 on its lower base and a conical deflecting partition 105, inside and perfectly centered, these openings 104 being reinforced by seals 106-106 'ensuring their tightness against the upper base of the cartridge 102, the openings 104 then facing the inlet 107 located on the perimeter of the air in the cartridge 102 , to reach its interior through the many perforations it contains.

The connector 101, on its upper base, has a large central orifice 109 establishing the access of the fluid to its interior and at the same time this base is extended into a hollow body 110, of the same axis and facing the orifice 109. A second hollow body 111 moves telescopically inside the hollow body 110 and protrudes at the upper end of the latter and, in turn, is also provided at its upper end with a valve 112 which, of course, controls the fluid discharge.

This valve 112 has a large diameter cylindrical configuration with inside a piston 113 which, in the closed situation, rests by means of a seal 114 on the seat 115 defined on the upper mouth of the body 111, this piston acting axially in a cylindrical skirt 116 established in the body of the valve and the lower edge of which leaves a passage 117 for communication via the line 118 with the reservoir 119 supplying the projection pressure.

The body of the valve 112, on its upper base, that is to say above the piston 113, has an orifice 120 through which the valve receives pressure from the network.

According to what has just been explained, when the network pressure reaches the valve 112 through the orifice 120, since the piston 113 offers at this pressure a surface clearly greater than that which it offers through the passage ring 117 at the pressure existing in the tank 119, the valve remains closed.

At the moment when, using a corresponding solenoid valve, the network pressure arriving at the valve 112 through the orifice 120 is interrupted, the pressure of the reservoir 119 forces the piston to retract in the upward direction, which causes the instantaneous discharge of the fluid through the hollow bodies 111 and 110 of the nozzle 101 and of the inlet 107 of the cartridge, and therefore, the projection by emptying of the latter towards the core boxes.

To make the necessary displacements of the end piece 101 so that it adapts to the cartridge 102 or deviates therefrom to allow the replacement of the latter, on the bodies 110 and 111 is located an end piece cylinder 121, axially enveloping the latter, rigidly assembled with the upper hollow body 111, as shown in detail in FIG. 6, and associated by means of seals 122 with the lower tubular body 110, allowing the axial displacements of the latter. To the lower hollow body 110 is secured a ring 123 sealed by means of segments 124 on the internal face of the cylinder nozzle 121, and defining with the latter two chambers 125 and 126, or rather a chamber compartmentalized in two sub-chambers 125 and 126 each of which has a respective inlet 127 and 128 situated at the lower and upper ends respectively in the together. Thus, when the fluid arrives through the upper inlet 128, an overpressure in the chamber 126 is produced forcing the lower hollow body 110 and, consequently, the nozzle 101 to move in the descending direction until it stops against the cartridge 102, the assembly then being in projection condition. On the contrary, after the projection and due to the admission of the pressurized fluid through the inlet 127, an overpressure in the lower chamber 125 is produced acting on the ring 123, integral with the lower hollow body 110, overpressure which pushes the latter in the ascending direction, which produces the spacing of the nozzle 101 relative to the cartridge 102 in order to allow easy replacement of the latter.

Finally and in addition to the above structure, the nozzle 101 has a radial outlet 129 for the rapid expulsion of the pressure at the end of the spraying, outlet matched with a valve 130 which opens during closing valve 112, this outlet also being accompanied by a silencer dampening the sound of the rapid discharge of air.

Figures 7 and 8 show the sand residue cleaner constituting another objective of the invention and which is constituted by a support piece 201, rigidly subject to the frame or chassis 202 of the machine, this support 201 obviously being fixed and supporting integrally a vertical cylinder 203, the rod of which receives a second support 204, obviously movable and displaceable in the vertical direction on which a tilting platform 205 is fitted.

The specific utility of cylinder 203 above is to authorize the elevation of the movable support 204 and the platform 205 to a level in height allowing to receive the projection plate 206 having been moved laterally in this zone by the cartridge-holding carriage to the end of the projection phase.

More specifically, the platform 205 is extended at its right end by a connecting rod 207 hinging on the movable support 204 through a tilting axis 208 located substantially in correspondence with the external limit of the platform 205 while that the free end of the connecting rod and by means of an articulated assembly 209 is united to the rod 210 of another hydraulic cylinder 211, mounted with the possibility of tilting on the own support 204 on the transverse axis 212.

Under these conditions and as is clear from the simple observation of FIG. 8, the actuation of the cylinder 211 in the direction of retraction of its rod 210, causes the rod 207 to tilt on the axis 208 which, at its turn, produces the tilting of the platform 205 from the situation represented in a continuous line in the figure until the situation represented in a line of lines. Consequently, the projection plate 206 performs the same displacement which, therefore, results in its automatic cleaning, that is to say the impulse and fall of the sand remains 213 deposited on this plate during the phase of machine operation corresponding to the projection on the core.

In order to secure the projection plate 206 on the tilting platform 205, during this tilting operation, two lateral claws 214 have been provided intended to act on the opposite edges of the plate 206, claws which are integral with the respective hydraulic cylinder rods 215 associated with supports 216 emerging laterally and below the platform 205 so that the drive of these cylinders, after the "hooking" of the claws 214 on the edges of the plate ensures perfect immobilization of the latter for any height.

• Le chariot porte-plaque de projection avec la cloche et la plaque est latéralement déplacé vers le côté de la machine, où se trouve le nettoyeur. Ensuite, la plaque est rendue indépendante du reste des éléments au moyen de l'élévation préalable de la plate-forme 205 à l'aide du cylindre hydraulique 203, les griffes 214 sont accrochées sur le bord de la plaque 206 et les cylindres hydrauliques 215 sont actionnés afin que la plaque demeure parfaitement assemblée sur la plate-forme 205 ; auparavant le cylindre 203 descend et retire le chariot porte-pfaque. Finalement, le cylindre hydraulique 211 est actionné, ce qui entraine le brusque basculement de la plate-forme 205 et en conséquence de la plaque de projection 206, et par suite l'évacuation des restes de sable 213 s'y trouvant. Un nouvel actionnement du cylindre 211, cette fois dans le sens contraire, entraine le basculement, également dans le sens contraire de la plate-forme, jusqu'à la position horizontale, la plaque, parfaitement nettoyée redevenant en condition de recevoir une nouvelle cartouche afin que la machine s'engage dans un nouveau cycle de travail.

Thus, and according to the above arrangement, the operation of the cleaner is as follows:

• The projection plate carriage with the bell and the plate is moved laterally towards the side of the machine, where the cleaner is located. Then, the plate is made independent of the rest of the elements by means of the prior elevation of the platform 205 using the hydraulic cylinder 203, the claws 214 are hung on the edge of the plate 206 and the hydraulic cylinders 215 are actuated so that the plate remains perfectly assembled on the platform 205; beforehand the cylinder 203 descends and withdraws the plate-carrying carriage. Finally, the hydraulic cylinder 211 is actuated, which causes the abrupt tilting of the platform 205 and consequently of the projection plate 206, and consequently the evacuation of the sand remains 213 therein. A new actuation of the cylinder 211, this time in the opposite direction, causes the tilting, also in the opposite direction of the platform, to the horizontal position, the plate, perfectly cleaned again becoming in condition to receive a new cartridge in order that the machine enters a new working cycle.

As indicated, the platform 205 rests on the mobile support 204 through the tilting axis 208, but moreover on a seat or stop 217 having the particularity of being adjustable in height in order to obtain perfect horizontality of the platform.

Claims (12)

1) Improvements made in the machines for cleaning cores, specifically in their installation for automatic change of boxes, essentially characterized in that they consist of the arrangement of a pair of horizontal slides, intended to be located in correspondence with the transverse and mean plane of the machine, slides where one can define three sectors, one of which is intermediate and facing in operation the working area of the machine and the other two, extremes emerging laterally from this last, having been provided that on the slides are located a pair of carriages, adjacent in the lateral direction, carrying boxes with corresponding cores, so that in a precise position of the carriages relative to the slides, it is one of them which occupies the intermediate sector and is facing the working area of the machine, while the other carriage remains offset laterally allowing the r location of the core box already used by another new, however that the movement of these carriages on the slides leads to the placement of the carriage, previously inoperative, in the intermediate sector of the slides and, therefore, vis-à-vis the machine operating area, while the carriage previously in the operating area, is now laterally moved for the replacement of the corresponding box. 2) Improvements according to claim 1, characterized in that each of these carriages comprises at its upper part another pair of slides, transverse with respect to the preceding ones, on which the respective core boxes with the projection plates are capable of displacement corresponding, each of these core boxes offering the particularity of being able to adopt two positions with respect to the corresponding lower carriage, one of which this carriage is in alignment with the lower longitudinal slides with a view to its coincidence with the operating area of the machine, and the other where the carriage moves perpendicularly for the automatic change of the core box. 3) Improvements according to claim 1, characterized in that each of the lower carriages has a U-shaped configuration with vertical branches relative to the displacement slides, by establishing inside this U means for displacement relative to each of the trolleys of the corresponding core boxes. 4) Improvements according to the preceding claims, characterized in that the two lower carriages are secured to each other by means of a spacer and are connected to the ends of a chain which, using end gear wheels, produces their drive when the chain is actuated by a mono-reduction group. 5) Improvements according to the preceding claims, characterized in that in each lower carriage, on the bottom of their U-shaped transverse groove, two toothed wheels are positioned at the ends, being connected together by means of a chain and being driven also by a gear motor, this chain integrally driving a sliding shoe on auxiliary slides using four pairs of wheels, shoe which in turn causes the corresponding cores box arranged to be thus moved. 6) Improvements according to the preceding claims, characterized in that both the lower and upper slides have a rectangular section of which one of the diagonals is in vertical arrangement, and that at the same time the wheels, complementarily, have on their periphery a hollow V-groove in correlation with the profile of the slides. 7 °) Improvements made in the machines for cleaning cores, more specifically in their projection mechanism adaptable on the mouth of the sand cartridge prior to the projection itself, and separable from the latter at the end of the projection phase for the replacement of the cartridge, characterized in that this mechanism is composed of an end piece, adaptable on the upper face of the cartridge, hollow, having two opposite openings on its lower face, a centered and large diameter orifice on its upper face and a conical internal deflecting partition, also centered, this endpiece being integral through its upper face with a hollow body surrounding its orifice, inside which plays a second hollow body, also of large diameter, which emerges through its upper end and which, also by its upper end, determines a projection valve in which is housed a piston receiving the network pressure under fo rme axial and through a small orifice, at the same time as it also receives the pressure from a reservoir containing the fluid supplying the projection pressure, in this case in radial form. 8 °) Improvements according to claim 7, characterized in that the piston of the projection valve, with large diameter, plays in the body of the latter guided by an annular skirt integral with the body of the valve by its upper end and with its lower and free edge substantially spaced from the lower base of the valve body, defining therein a wide circular communication passage with the container, while the small-diameter orifice for communication of the projection valve with the network pressure is located on the upper base of the valve body, so that the piston offers a substantially larger area at the network pressure while remaining in the closed position on the mouth of the upper hollow body during the presence of this pressure, while a stop of the latter causes the instantaneous retraction of the piston in the ascending direction and the discharge of the fluid contained in the reservoir through the telescopic tubes and the nozzle to the cartridge. 9) Improvements according to claims 7 and 8, characterized in that the hollow and telescopic bodies are axially surrounded by a tip cylinder secured by its upper end to the upper hollow body and which is connected by its lower end with the lower hollow body through seals ensuring sealing between these elements along the movements of the lower hollow body, having been provided that on it is placed a ring provided on its outer periphery with sealing adapter segments the internal face of the end cylinder and defining two chambers, one lower and the other upper, provided with respective fluid inlets which also occupy positions at the upper and lower ends, so that the access of the fluid through the upper inlet to the upper chamber, causes the downward displacement of the movable hollow body and, consequently, the displacement of the nozzle towards the cartridge, alo rs that the admission of pressure through the lower inlet causes a movement in the opposite direction, that is to say the separation of the nozzle relative to the cartridge for the replacement thereof. 10 °) Improvements according to claims 7, 8 and 9, characterized in that the endpiece is provided with a radial outlet for rapid exhaust, comprising a valve synchronized with the projection valve and which opens during the closing of the latter, this exhaust being assisted by a silencer. 11) Improvements made in the machines for cleaning cores, more specifically in their means for cleaning sand residues, characterized in that these means consist of a device formed from a fixed support, integral with the frame of the machine in forming a lateral extension, in relation to the first through a hydraulic cylinder of vertical axis having a function of raising the movable support until it reaches the operating plane of the projection plate from which one is held to remove the sand remains, having been provided that on this mobile support is arranged a tilting platform on which the projection plate will rest during the cleaning phase, platform which is connected to the support through an axis of tilting located in correspondence with its extreme edge, resting at the same time on this support by its external edge by means of a height-adjustable stopper, offering the particularity that on the other side of this bottom axis base of the platform, this extends into a connecting rod which, by its lower and free end, receives in articulation the rod of a second hydraulic cylinder in substantially horizontal arrangement, the body of which is mounted with a possibility of tilting on the own movable support, all in such a way that the actuation of this last cylinder causes the tilting of the connecting rod and consequently the tilting of the platform from a first horizontal plane to a substantially vertical plane in view of the impulse and the falling of the sand remains on the projection plate assembled on this platform. 12 °) Improvements according to claim 11, characterized in that the projection plate, prior to the tilting of the platform, is fixed on the latter by means of a pair of lateral claws being intended to hang on edges opposite of the latter, offering the particularity that these claws are integral with the rods of respective hydraulic cylinders themselves being fixed to supports emerging laterally and down from the tilting platform.

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