EP0524302B1 - Method and devices for decoring castings - Google Patents

Abstract

PCT No. PCT/FR92/00095 Sec. 371 Date Nov. 12, 1992 Sec. 102(e) Date Nov. 12, 1992 PCT Filed Feb. 4, 1992 PCT Pub. No. WO92/13603 PCT Pub. Date Aug. 20, 1992.Sand cores are broken up and removed from castings, particularly from cylinder heads from internal combustion engines. A pneumatic hammer is applied to the casting while the casting is held against a low pressure cylinder. The casting is subjected to horizontal oscillation by a receiver actuated by a rod and a double eccentric rotatably driven by a geared motor.

Description

The invention relates to a method and a device for cleaning casting cores for foundry parts.

Elimination of casting cores on architectural foundry pieces quite complex, very often requires the use of a hammer pneumatic, allowing the part to be subjected to repeated shocks, likely to break the adhesion of the sand on the walls.

Originally, this work was carried out by holding the pneumatic hammer at the hand, relying on the dexterity and expertise of the operator; this resulted in certain disparities in the result obtained and the scrapping of a fairly large proportion of the finished parts offering incomplete cleaning.

In order to rationalize this operation and to protect the operator resulting nuisance: noise, dust, it has been considered to use devices such as those described in the French patent No. 2,311,617 and European Patent No. 0.144.031. These devices are essentially consisting of a chassis, on which one or more several pieces to be cleaned; the said chassis being subjected to vibrations likely to cause takeoff and fractionation of nuclei.

To further increase the efficiency of this device, provision has been made, in French patent 2,470,652, to have several chassis on a polygonal carousel, rotated step by step in front of a station diametrically opposite loading station and unloading station.

However, it must be noted that the vibrations applied in this way parts regularly do not guarantee splitting sufficient of the nucleus, nor a total takeoff of all fractions of it.

It results from this situation a certain reluctance of the designers to resort to complex architectures, likely to contradict this cleaning operation, when it would however be very desirable for later use of the part.

This problem is of particular importance for cylinder heads. internal combustion engine, the most complex of which are very often impossible to completely disburse, with what this implies as a disruption on the production lines and as a waiver for designers.

The object of the present invention is to remedy these drawbacks. This invention, as it stands, solves the problem consisting of defining a process and creating devices with which kernels can be not only fragmented, but also totally disaggregated, while causing an eroding effect takeoff of all sand particles, before complete evacuation by gravity in a single phase, preferably without repositioning of the part on its support.

• l'application de chocs, à fréquence élevée, directement sur la pièce, alors que celle-ci est maintenue en appui contre un matelas pneumatique pour obtenir le fractionnement du noyau,; cette première opération étant suivre de deux autres opérations connues de l'art antérieur, et notamment du document EP-A-0144031, à savoir:
• balancement de la pièce selon un mouvement alternatif,
• élimination du Sable par gravité, au fur et à mesure de la désagrégation du noyau.

The method according to the invention is essentially characterized in that it comprises a first operation which consists in

• the application of shocks, at high frequency, directly on the part, while the latter is held in abutment against an air mattress to obtain the fractionation of the core; this first operation being followed by two other operations known from the prior art, and in particular from document EP-A-0144031, namely:
• rocking of the part in an alternating movement,
• elimination of sand by gravity, as the nucleus disintegrates.

The first two operations of the method according to the invention allow to obtain the total disintegration of the nucleus, the second operation, namely alternative balancing of the workpiece, further enabling a certain sandblasting effect of the workpiece molded.

According to one mode of application of the method, alternative balancing results from the combination of a reciprocating longitudinal movement an alternative transverse movement.

According to a first variant of the above application mode, the reciprocating transverse motion is applied in a parallel plane to the one in which the longitudinal movement is applied.

According to a second variant of the same mode of application of the method, the alternative transverse movement is applied in a perpendicular plane to the one in which the longitudinal movement is applied.

According to a particular definition of the process, the balancing of the work is performed with an amplitude and an adjustable frequency respectively from 0 to 10 cm and from 0 to 85 Hz.

According to another particular definition of the method, the rocking of the piece is performed in combination with the take-up of a clearance J, introducing an additional inertial effect on the sandy mass.

Whatever the mode of application and the definition of the process, the amplitude and frequency of the swinging of the piece varies, swing course, according to rules determined according to the internal architecture of the room and the size of the cavities.

According to another definition of the process, the frequency of rocking is irregular and random.

A device for applying the basic method according to the invention is characterized in that the high frequency shocks are applied directly on the workpiece using a pneumatic hammer, fixed on a support integral with a frame, arranged so as to strike directly the workpiece by passing the hammer through an orifice formed for this purpose in a fixed support plate, against which the workpiece is held in place by a clamping plate and a chamber cylinder, supplied with low pressure, which constitutes the air cushion, in that the swinging of the part, which takes place according to a horizontal reciprocating movement is obtained through a receiver, comprising the support plate, the clamping plate and the clamping cylinder, connected to the frame vertically by four connecting rods and horizontally by a connecting rod and a double eccentric, rotated by means of a gear motor, and in this that the elimination of sand by gravity is obtained by maintaining in position vertical of the part, by abutting it against a mechanical stop secured to the support plate.

The receiver preferably consists of two side plates, swan neck shaped, connected together by the support plate and by a connecting plate, supporting the pneumatic cylinder with chamber bearing, on the one hand, against the connection plate and against the clamping plate mounted by means of slides on four slides connecting the support plate to the connection plate, perpendicular to them.

The vertical connecting rods are connected to the side plates via elastic joints.

The horizontal connecting rod is connected to the connection plate via of a screed.

According to another embodiment of the device according to the invention described above, the receiver is fitted with a workpiece box, mounted with a certain clearance between the connection plate and the support plate, supported by four vertical rods fixed against the internal wall side plates by means of elastic articulation, or directly on the chassis by the same means.

When a clearance J must be made between the clamping plate and the part, this is obtained by mounting sleeves, of length determined according to the thickness of the part, on the slides, between the plate support and the clamping plate, or by means of two jacks, mounted in opposition, passing through the connecting plate, the rod of one of which is fixed to the yoke and the rod of the other of which comes to bear against the clamping plate for controlling the clearance J to be formed between said clamping plate and the part; said plate then being made integral with its slides by means of a blocking system incorporated in the slides.

According to a preferred embodiment of the first device according to the invention, two receivers are mounted on the same frame, both on the other a unique double eccentric, thus ensuring the balancing simultaneous two pieces in line with two hammers tires arranged at each end of the frame.

According to the first variant of application of the method according to the invention, the transverse reciprocating movement is obtained through a crankshaft connected to a workpiece holder by at least a connecting rod in that said work-holding capsule is supported by a built by means of four links articulated in planes perpendicular to the crankshaft and in that the frequency of swaying alternative is made irregular and random by variation corresponding to the speed of rotation of the drive motor crankshaft.

According to the second variant of application of the method according to the invention, the transverse reciprocating movement is obtained in a perpendicular plane longitudinal movement via a crankshaft connected to the workpiece holder by at least one bearing fixed under the latter, and springs, interposed vertically between the capsule workpiece and the frame, and in that the frequency of the alternating swing is made irregular and random by corresponding variation the rotational speed of the crankshaft drive engine.

The crankshaft is arranged in the longitudinal median plane of the capsule workpiece carrier while the springs are divided into two rows arranged symmetrically with respect to the crankshaft.

According to another embodiment of the first application variant of the method according to the invention, the reciprocating longitudinal movement and the reciprocating transverse movement are combined in a same movement ensuring the overall alternative swing by through two crankshafts arranged vertically between a frame and a workpiece holder support, and in that the frequency of alternative swing is made irregular and random by variation corresponding to the speed of rotation of the drive motor crankshafts.

whatever the application variants of the process and their modes of realization, the speed variation of the drive motor of the eccentric or the crankshaft is obtained through a electronic dimmer controlled.

The advantages obtained with this invention consist essentially of in that hollow rooms, of complex architecture, such as internal combustion engine cylinder heads, can be made by molding, without risk of difficulty in removing all of the core, while improving the surface condition of the walls by sanding effect, thus promoting the subsequent flow of liquid fluids or gaseous, intended to circulate in the cavities formed inside of the room, according to a very complex architecture.

• la figure 1 représente une vue de face d'un dispositif à mouvement alternatif longitudinal, sans jeu longitu dinal, appliquant le procédé de base,
• la figure 2 représente une vue de dessus du dispositif selon la figure 1,
• la figure 3 représente une vue de face d'un dispositif avec jeu longitudinal,
• la figure 4 représente une vue de dessus du dispositif selon la figure 3,
• la figure 5 représente une vue de face d'une variante de réalisation du dispositif à mouvement alternatif longitudinal avec jeu longitudinal,
• la figure 6 représente une vue de dessus du dispositif selon la figure 5,
• la figure 7 représente une vue de face d'un mode de réalisation particulier du dispositif à mouvement alternatif horizontal avec jeu longitudinal,
• la figure 8 représente une vue de dessus du dispositif selon la figure 7,
• les figures 9, 10 et 11 représentent, respectivement, une vue de face, une vue de dessus et une vue de côté d'un dispositif à deux postes,
• la figure 12 représente une vue de face schématique du dispositif de débourrage selon un mode de réalisation correspondant à la première variante d'application du procédé,
• la figure 13 représente une vue de face schématique du dispositif de débourrage selon un mode de réalisation correspondant à la seconde variante d'application du procédé,
• la figure 14 représente une vue de côté schématique en perspective, du dispositif de débourrage selon la première variante d'application du procédé selon l'invention, correspondant à un mode de réalisation particulier de celle-ci.

Other characteristics and advantages will appear in the description which follows of an embodiment of the invention, intended for the cleaning of cylinder heads of engines, given by way of nonlimiting example with regard to the appended drawings in which:

• FIG. 1 represents a front view of a device with longitudinal reciprocating movement, without longitudinal play, applying the basic method,
• FIG. 2 represents a top view of the device according to FIG. 1,
• FIG. 3 represents a front view of a device with longitudinal play,
• FIG. 4 represents a top view of the device according to FIG. 3,
• FIG. 5 represents a front view of an alternative embodiment of the device with longitudinal reciprocating movement with longitudinal clearance,
• FIG. 6 represents a top view of the device according to FIG. 5,
• FIG. 7 represents a front view of a particular embodiment of the device with horizontal reciprocating movement with longitudinal play,
• FIG. 8 represents a top view of the device according to FIG. 7,
• FIGS. 9, 10 and 11 represent, respectively, a front view, a top view and a side view of a device with two stations,
• FIG. 12 represents a schematic front view of the cleaning device according to an embodiment corresponding to the first variant of application of the method,
• FIG. 13 represents a schematic front view of the cleaning device according to an embodiment corresponding to the second variant of application of the method,
• FIG. 14 represents a schematic side view in perspective, of the cleaning device according to the first variant of application of the method according to the invention, corresponding to a particular embodiment of the latter.

Figures 1 and 2 show a part 1, mounted on a device for fractioning and discharging the casting core of foundry parts according to the invention, comprising a pneumatic hammer 20 with hammer 21, fixed on a support 3 integral with a frame 4 arranged so as to strike the part 1 directly by passing the hammer 21 through an orifice 401, formed, for this purpose, in a fixed support plate 40 with vertical stop 402, against which the part 1 is held by means of a clamping plate 41 subjected to the action of a chamber cylinder 50, supplied with low pressure, constituting an air cushion; said support plate 40 and said clamping plate 41 are part of a receiver 60, connected to the frame 4 vertically by four connecting rods 70 with elastic articulation 71 and horizontally by a connecting rod 72 connected, on the one hand, to a double eccentric 80 driven by a variable speed motor reducer 81 and, on the other hand, via a yoke 431 to a connection plate 43 supporting the chamber cylinder 50 , connecting transversely, in combination with the plate support 40, two side plates in the form of a swan neck 61, 62 ; the clamping plate 41 is mounted, by means of slides 411, on four slides 412 connecting the support plate 40 to the connection plate 43.

FIGS. 3 and 4 represent a part mounted with a clearance J on a device for fractioning and evacuating the casting core, which differs from that shown in FIGS. 1 and 2 only by the presence of sleeve 413, forming a stop, on the slides 412, between the support plate 40 and the clamping plate 41.

By examining Figures 1 and 2 in more detail, it will be noted that, provided that the useful length of the connecting rod 72 has been previously adjusted in order to obtain a necessary and sufficient spacing between the support plate 40 and the clamping plate 41, for a given empty length, of the chamber cylinder 50, the parts 1 can be directly introduced from above, or, optionally, laterally, into the space thus formed between the two plates 40, 41, it being understood that the stop 402 existing on the support plate 40 limits the penetration of the part 1 in this space, without the need to use any blocking system. Note that on certain flat parts, the parts can be clamped directly, without interposing the clamping plate 41.

The receiver 60 then being brought at the end of the stroke to the pneumatic hammer 20, by controlled action on the double eccentric 80 via the gear motor 81, the operation can then begin, since the hammer 21 of the pneumatic hammer 20 can - strike directly on the part, passing through the orifice 401 provided for this purpose. These hammering actions, at high frequency, on the resonant assembly, consisting of the part 1 with its clamping plate 41 and of the chamber cylinder 50 at low pressure, cause, in the vicinity of the natural frequency of resonance of the system, a fractionation and takeoff of the nucleus. This resonance phenomenon can be controlled by acting on the inflation pressure of the chamber cylinder 50 and on the frequency of hammering.

This operation being completed, the complete disaggregation of the pieces of core can then be undertaken, by implementing the swinging back and forth of the part 1 by action on the receiver 60 supported by the vertical connecting rods 70, by switching on. continuous of the geared motor 81 causing the double eccentric 80 which communicates, to said receiver 60, a reciprocating horizontal movement, of course and frequency determined by means of the connecting rod 72 and the yoke 431 fixed perpendicular to the connection plate 43. The pieces of nucleus, resulting from the fragmentation produced during the previous operation, undergoing inertia effects, which cause, by knocking, their progressive disintegration; operation which causes a certain erosion of the asperities which can remain in the inaccessible cavities and a complete detachment of the most adherent sandy particles, by an effect of "sanding" well known in mechanics.

Provided that the part 1 is presented accordingly on the receiver, the sand resulting from the disintegration of the core flows by gravity between the side plates 61, 62 of said receiver and the side members of the frame 4. This sand can be discharged at the gradually by a conveyor belt. The swing frequency and its amplitude can, respectively, be adjusted, by action on a speed regulator and by action on the double eccentric.

In some cases, the disintegration action of the core fragments may be further increased, by providing a clearance J between the so-called clamping plate 41 and the part 1, by adding a sleeve 413 of appropriate length on the slides 412 ( Figures 3 and 4), or, as shown in Figures 5 and 6, by means of two jacks 55 and 56, mounted in opposition and passing through the connecting plate 43, the rod 551 of one of which is connected to the yoke 431 and whose rod 561 on the other comes to bear against the clamping plate 41, or directly against the part 1, to ensure, therein, a clearance J controlled in the horizontal plane; the clamping plate 41 then being secured to its slides by means of locking devices, incorporated in the slides 411. Thus, the jack 55 ensures the approach of the clamping plate as a function of the thickness of the part and the jack 56 only provides clearance J. this arrangement, which corresponds to FIGS. 3 to 6, makes it possible to further increase the effect of inertia and, consequently, the collision between the pieces of core; it also facilitates the evacuation of sand, when dealing with parts with fairly complex internal architecture.

According to the particular embodiment of the invention, shown in Figures 7 and 8, the part 1 is fixed in the receiver 60 by means of a housing 90, mounted with clearance between the connecting plate 43 and the plate support 40, made integral with the side plates 61 and 62 of the receiver, or of the chassis (as shown in the figures), by means of four vertical links 73 fixed by means of elastic articulation 71. The part is locked against one of the short sides 91 of the housing, located towards the pneumatic hammer 20, by means of a chamber cylinder 50 bearing against the small opposite side 92 of said housing 90, with or without interposition, d 'a clamping plate 41 . It is thus possible to obtain a combined rocking of the part 1 by means of the receiver 60 and of the housing 90, by accompanying the latter with shocks due to the clearance provided between the housing and the connection plates 43 and d 'support 40.

We understand that it is interesting to combine two devices, in order that they use, in common, the double eccentric and its drive motor, as shown in Figures 9, 10 and 11.

Figures 12 to 14 show a frame 1000,190 supporting a workpiece capsule 200 or a capsule support 1000 by means of links 500, springs 700 or crankshafts 180, actuated respectively by a crankshaft 300, one or more connecting rods 400 and a drive motor 600.

By examining more particularly FIG. 12, it is noted that the workpiece capsule 200 is connected to the frame 1000 by means of links 500, which can be common with those allowing the longitudinal swing, provided that their articulations are designed accordingly. (knee pads or double axis of articulation); the lateral swinging being ensured by the connecting rod 400 , driven by a reciprocating movement by means of the crankshaft 300. It is obvious, for the skilled person, that the frequency of the alternating swinging thus created and maintained by the engine 600, could be made random by simple random variation of the speed of rotation of said motor 600 ; which can be easily obtained by means of an electronic variator, the control of which is ensured accordingly.

Referring to FIG. 13, it is noted that, in this embodiment, the workpiece capsule 200 is connected to the frame 1000 by means of the crankshaft 300, in direct engagement, on the underside of said capsule 200, and two rows of springs 700, arranged on each side of the crankshaft and ensuring the return to the vertical position of the capsule 200, while creating, with this, a vibrating system, which, combined with a random variation of the rotation speed of the crankshaft, obtained as indicated in the example above, will generate and maintain a random alternating swing of said workpiece carrier capsule 200. In this embodiment, the longitudinal swing can be obtained by alternating sliding of the bearing 201, connecting the workpiece capsule 200 to the crankshaft 300, on the crankpin of said crankshaft, provided that the length thereof is predetermined accordingly to provide sufficient sliding freedom.

By now examining FIG. 3, it is noted that, in this embodiment, the longitudinal swing and the transverse swing of the support 100 are combined in the circular movement of the crank pin 181 of the crankshafts 180 relative to the drive shaft 182 of these latter. The swing thus obtained can be made irregular and random, in this case too, by varying the speed of rotation of the crankshaft drive motor, using the means already mentioned in the other examples.

Note that in the examples shown in Figures 12 and 13, the frequency of the longitudinal swing can be made, it also, random by random variation of the rotation speed of the motor assigned to this function.

The method and the device according to the invention mainly concern the cleaning of the internal combustion engine cylinder heads, but nothing prevents their use for the elimination of the nucleus other foundry pieces with the same internal complexity, subject to minor adaptations.

Claims (22)

1. Method for fractioning and evacuating foundry parts from the smelting core and including the following successive operations :

   applying high frequency impacts directly to the part (1) when the latter is kept in support against a pneumatic cushion so as to fraction the core,

   alternative horizontal balancing of the part (1) so as to obtain the total disintegration of the core and a sand blasting effect of the internal walls of said part (1),

   elimination of the sand by means of gravity as the core gradually disintegrates.
2. Method according to claim 1, wherein the alternative balancing results from combining an alternative longitudinal movement with an alternative transversal movement.
3. Method according to claim 2, characterised in that the alternative transversal movement is applied inside a plane parallel to the one in which the longitudinal movement is applied.
4. Method according to claim 2, characterised in that the alternative transversal movement is applied inside a plane perpendicular to the one in which the longitudinal movement is applied.
5. Method according to claim 1 or 2, characterised in the alternative balancing of the part (1) accompanies the elimination of play (J) introducing an additional inertia effect on the sandy mass.
6. Method according to claim 1 or 2, characterised in that the balancing of the part is carried out with an amplitude able to be adjusted from 0 to 10 cm.
7. Method according to claim 1 or 2, characterised in that the amplitude and frequency of balancing vary during the latter according to rules determined according to the internal structure of the part (1) and the dimension of the cavities.
8. Method according to claim 7, characterised in that the frequency of balancing is between 0 and 85 Hz.
9. Method according to claim 1 or 2, characterised in that the frequency of balancing is irregular or random.
10. Device for fractioning and evacuating foundry parts from the smelting core for implementing the method according to the preceding claims, characterised in that it comprises a pneumatic hammer (20) secured to a support (3) integral with a frame (4) and disposed so as to directly strike the part via the passage of the hammer (21) through an orifice (401) provided to this effect in a fixed support plate (40) against which the part (1) is supported by means of a clamping plate (41) and a chamber jack (50) fed at low pressure and constituting an air cushion, said support plate (40) and said clamping plate (41) forming part of a receiver (60) vertically connected to the frame (4) by four connecting rods (70) and by a connecting rod (72) activated by a double cam (80) driven in rotation by means of a back-geared motor (81), the part (1) being kept in a vertical position by abutting against a mechanical stop (402) integral with the support plate (40).
11. Device according to claim 10, characterised in that the receiver (60) is made up of two lateral plates with the shape of a swan neck (61, 62) interconnected by the support plate (40) and by a linking plate (43) supporting a pneumatic chamber jack (50) taking support on firstly against the linking plate (43) and secondly against the clamping plate (41) mounted by means of sliding blocks (411) on four slides (412) connecting the support plate (40) to the linking plate (43) perpendicular to the latter.
12. Device according to claim 10, characterised in that the vertical connecting rods (70) are connected to the lateral plates (61, 62) by means of elastic joints.
13. Device according to claim 10, characterised in that the horizontal connecting rod (72) is connected to the linking plate (43) by a clevis (431).
14. Device according to claim 10, characterised in that two receivers (60) are mounted on a given frame on both sides of a sole double cam (80), thus ensuring the simultaneous balancing of two parts (1) in the alignment of two pneumatic hammers (20) disposed at each of the ends of the frame.
15. Device according to claim 10, characterised in that, when play (J) needs to be fitted between the clamping plate (41) and the part (1), the latter is obtained by sleeve mounting (413) having a length determined according to the thickness of the part (1) on slides (412) between the support plate (40) and the clamping plate (41).
16. Device according to claim 10, characterised in that, when play (J) needs to be fitted between the clamping plate (41) and the part (1), the latter is obtained by means of two jacks (55 and 56) mounted in opposition and traversing the linking plate (43), the rod of one (551) being connected to the clevis (431), the rod of the other (561) controlling the introduction of play (J) between the part (1) and the clamping plate (41), the latter (41) then being rendered integral with its slides (412) via locking carried out at the level of the slide blocks (411).
17. Device according to claim 10, characterised in that the part (1) is mounted in the receiver (60) by means of a box (90) disposed with play between the linking plate (43) and the support plate (40) joined with respect to the lateral plates (61 and 62) of the receiver (60) by means of vertical connecting rods (73) with an elastic joint (71), said part (1) being rendered immobile against one of the small sides (91) of the box (90) situated towards the pneumatic hammer (20) by means of at least one chamber jack (50) taking support against the side (92) opposite the box.
18. Device according to claim 10, characterised in that, so as to ensure the transversal alternative movement, it comprises a crank (300) connected to a part holder capsule (200) by at least one connecting rod (400), said part holder capsule (200) being supported by a frame (1000) by means of four small connecting rods linked in planes perpendicular to the crank (300) which is driven by a motor (600) whose variation of the speed of rotation is able to make the frequency of the alternative balancing irregular and random.
19. Device according to claim 10, characterised in that, so as to ensure the transversal alternative movement, it comprises a crankshaft (300) connected to the part holder capsule (200) by at least one bearing (201) fixed under the latter, and springs (700) inserted vertically between said part holder capsule (200) and the frame (1000), the crankshaft (300) being driven by a motor (600) whose variation of the speed of rotation is able to make the frequency of the transversal alternative balancing irregular and random.
20. Device according to claim 19, characterised in that the crankshaft (300) is disposed inside the median longitudinal plane of the part holder capsule (200) when the springs (700) are distributed into two rows disposed symmetrically with respect to the crankshaft (300).
21. Device according to claim 10, characterised in that, so as to ensure a combined alternative longitudinal movement and an alternative transversal movement in a single movement, it comprises two crankshafts (180) disposed vertically between a frame (190) and a part holder capsule support (100), the frequency of alternative balancing being rendered irregular and random by the corresponding variation of the speed of rotation of the motor for driving the crankshafts (180).
22. Device according to one of claims 10 to 21, characterised in that the variation of the speed of the drive motor (81,600) is obtained by means of a controlled electronic variable-speed drive unit.

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