Continuous Kinematic Type Machine For Producing Foundry Cores

Abstract

Machine for the production of foundry cores with the aid of boxes. Said machine comprises feed barrel supplying the core boxes to a shot injection, this latter introducing the load into the boxes, then transferring these boxes to a hardening barrel which hardens the cores and transfers each box to a barrel for removing the cores and cleaning the boxes. This last barrel opens each box separately to bring the core onto the means for removing the cores, then cleans the boxes and closes them to transfer them to the feed barrel, which sends them back to the shot injection barrel.

Description

The present invention relates to a machine for the production of foundry cores.

Two types of processes for the production of foundry cores are used preferably. The first process involves incorporating a thermo-hardening material in the mixture from which the foundry core is to be moulded and thermally hardening the core in its moulding box. Such processes are called "hot box" processes, and these are relatively old.

The second group of processes, called "cold box" processes, involves the catalytic hardening of the core in its box at ambiant temperature. To this end, use is made of an auto-hardening reaction in the load incorporated in the moulded mixture in the box or of a gaseous fluid which causes hardening. It is generally considered that this latter process is perfectly suited to the rapid production of foundry cores.

At present, this "cold box" process, which certainly enables relatively rapid work to be carried out, is used with relatively little automation, and human intervention, even for the large scale production of cores, retains its importance to an extent that very appreciably restricts production rates and increases costs.

The object of the present invention is to remedy the situation by providing a machine which allows cores of any shape to be produced rapidly and automatically, restricting human intervention only to the replacement of the core boxes corresponding to the production run in progress by coe boxes of a new run.

The invention also proposes to provide a machine which enables cores of various shapes to be made rapidly and continuously without any reduction of yield, this machine being of the continuous kinematic type comprising operating barrels or turrets provided with means of support for receiving and transferring the products to be treated, each of these barrels also comprising tools that are controlled and that move with the barrel and intended to treat the products while they are being transported by this barrel, the products being transferred from one operating barrel to the other by transfer barrels or turrets, travelling thus in the machine assembly at a strictly uniform horizontal speed.

The invention relates to a machine for the production of foundry cores, said machine being characterized in that it comprises a feed barrel supplying core boxes to a shot injection barrel, the latter introducing the load into the boxes with the aid of injection heads, then transferring these boxes to a gasification barrel provided with gasification heads, passing a hardening gas through the load in each box, and transferring each box to a barrel for removing the cores and cleaning the boxes, this last barrel opening each box separately to bring the core onto a means for removing cores, then cleaning the boxes and closing them again to transfer them to the feed barrel which conveys them to the shot injection barrel, the assembly comprising a driving means synchronizing the movement of the various barrels, so that the operations and the transfers are effected in a continuous kinematic manner.

The application of continuous kinematics enables a machine to be constructed which can give very high production rates and is suited for the production of all types of cores.

The machine according to the invention has great flexibility as regards application since while being particularly suited for very large scale runs, it can also be used for medium or small runs, owing to the fact that the tools on the machine can be changed very easily and, in addition, it is possible to treat two different types of cores on the same machine.

The invention also relates to core boxes usable with this machine. These boxes are characterized in that each comprises at least one part fixed on the transfer plate carrying two positioning pins, and at least one movable part which can separate from the part fixed to the transfer plate along the plane of the joint, rocking locking devices mounted on the fixed part of the transfer enabling it to become integral with the movable part, the box comprising internal walls delimiting, when it is closed, a moulding cavity and two auxiliary cavities, the latter communicating with one another by means of the moulding cavity from which they are separated by filters, at least one opening for filling the moulding cavity and at least one opening for circulating gas in each of the auxiliary cavities being provided on the upper face of the box.

The boxes can be provided with one or a plurality of moulds, depending on the size of the core.

A same barrel of the machine can smultaneously treat cores boxes with joints in a vertical plane and boxes with joints in a horizontal plane.

According to another characteristic feature of the invention, each working or transfer barrel consititutes an independent unit, connected separately to the same driving unit.

This driving unit consists of a motor driving a reducer distributor connected to the transmission boxes of each of the barrels by means of flexible linkages such as cardan shafts.

The fact that the working and transfer barrels constitute independent units connected to a driving unit considerably simplifies the construction and assembly of the machine, as the latter can have very large overall dimensions, which would make if difficult to construct it in a single unit.

Each barrel is constructed and transported as an independent unit. To assemble the machine, the various barrels are placed first where the machine is to be located and then connected to the driving unit by the flexible transmission means provided in the form of cardans.

This drive by single driving unit also ensures that all the parts of the machine are completely synchronised, without there being any necessity for providing complex devices to ensure such synchronization, as would be the case for barrels having their own individual driving means.

The present invention will be described in greater detail with the aid of the construction of a machine for producing foundry cores by continuous kinematic means, illustrated schematically in the accompanying drawings in which:

FIG. 1a is a perspective view of a core box with its joint in a vertical plane.

FIG. 1b is a perspective view of a core box with its joint in a horizontal plane.

FIGS. 2a to 2d represent the various phases of the method according to the invention, in the case of a core box with its joint in a horizontal plane.

FIG. 3 is a schematic plan view of the machine according to the invention.

FIG. 4 represents a schematically, in vertical sections, the shot injection barrel of the machine according to the invention.

FIG. 5a is a part of an axial section of a gasification barrel and a gasification head.

FIG. 5b is a partial plan view of the gasification barrel and the gasification head.

FIG. 6a is a partial axial section of the barrel for the ejection of cores and the cleaning of the boxes, in the case of the equipment for the boxes with a vertical joint.

FIG. 6b is a partial axial section of the barrel for the ejection of cores and the cleaning of the boxes, in the case of equipment for boxes with a horizontal joint.

FIGS. 7a and 7b show the principle of continuous kinematics.

In FIG. 1a, reference point 1 relates to a core box with a vertical joint consisting of two parts 1a and 1b. Part 1a is fixed on the transfer plate 2 which serves to convey a part over the differential barrels of the machine for producing cores. Part 1b is movable. It is connected to the part 1a by the locking device 3 consisting essentially of levers comprising two arms 3a and 3b and moving together by means of the sleeve 4, around the axle 5, carried by the vertical faces perpendicular to the plane of the joint, of the fixed part 1a of the core box. The ends of the arms of the lever 3a are shaped into hooks which cooperate with the pins 6 fixed on the vertical faces, perpendicular to the plane of the joint, of the movable part 1b of the core box, so as to make part 1b integral with part 1a. The ends of the lever arms 3b carry some pins 7 which enable the levers 3 to be rocked around the axles 5 to disengage the pins 6 and enable the movable part 1b of the core box to be separated from the part 1a.

The upper horizontal part of the core box has an opening 8 which enables the moving mixture to be introduced into the core box, and openings 9 which enable a gaseous mixture to be introduced into the core box and to be removed from it.

The transfer plate 2 has fixed to it two positioning pins 10.

FIG. 1b shows a perspective view of a core box with its joint in a horizontal plane. The various members are designated on the box according to FIG. 1 by the same references as are given to the members fulfilling the same functions. The movable part 1b is placed here above the fixed part 1a and no longer laterally as in the case of a core box with its joint in a vertical plane.

FIGS. 2a and 2b represent schematically the various phases of the method according to the invention, in the case of a core box with its joint in a horizontal plane.

FIG. 2a shows schematically a sectional view in a vertical plane of the empty core box, as it is before being filled with the moulding mixture. The part 1a, fixed to the transfer plate 2 by the screws 11 is seen again, as also the movable part 1b.

The moulding cavity 12 is surrounded by the walls 13, which are separate from the outer wall of the core box. An intermediate partition 14 enables two cavities 15 and 16 to be delimited between the walls 13 and the exterior walls of the core box. These cavities communicate with one another by means of the openings 17, provided in the walls 13 and fitted with filters 18.

FIG. 2b shows schematically the operation involved in filling the box with the moulding mixture, this operation being called "shot injection."

An "injection head" 301 is pressed onto the upper horizontal face of a box so as to form a sealed joint 19 with the latter. The nature of this injection head is known and will not be shown in this figure. The exit orifice 20 of the injection head communicates with the opening 8 provided in the upper part of the box.

A mixture of compressed air and moulding mixture is injected into the box, following the arrows E, by means of a compressed air blast, so that the moulding mixture completely fills the moulding cavity 12, without however going beyond the openings 17, as it is is stopped from doing so by the filters 18 of which the meshes are finer than the grain constituting the moulding mixture. The compressed air, on the other hand, passes through the filters 18 and escapes from the core box through the opening 9, following the arrow S.

The moulding mixture thus introduced into the moulding cavity 12 consists essentially of foundry sand to which has been added a resin which can be polymerised by catalysts.

FIG. 2c shows schematically the so-called "gasification" operation. To carry out this operation, a "gasification head" 21 is applied onto the upper horizontal surface of the core box, by means of a sealing plate 22. The gasification head 21 comprises a feed channel 23, communicating with the cavity 16 of the core box by means of the orifice 24, and a discharge channel 26 communicating with the cavity 15 of the core box by means of the orifice 25.

Through channel 23 is introduced, in the direction of the arrow E' a gaseous hardening mixture consisting, for example of carbon dioxide to which triethylamine or dimethylamine has been added. This mix penetrates into the cavity 16 of the core box and then, passing through the openings 17 and the filters 18, into the moulding cavity 12, from which it emerges by the openings 17 and the filters 18 located in the opposite wall, and enters the cavity 15 and finally is evacuated through the channel 26 following the arrow S'.

In its passage through the moulding cavity 12, the hardening fluid enters into intimate contact with the moulding mixture and causes the polymerisable resin incorporated in this mixture to harden.

When the hardening fluid has thus circulated through the moulding mixture for sufficient time to ensure the complete polymerisation of the resin incorporated in this mixture, the inflow of the hardening gaseous fluid is arrested and compressed air for a sweeping operation is introduced through the channel 23. This compressed air follows the same path as had previously been followed by the hardening gaseous fluid and thus sweeps the moulding mixture in the cavity 12, diluting and carrying away the hardening gaseous fluid which had remained in the pores of the mixture and finally evacuating it to the channel 26.

FIG. 2d shows schematically the core ejection operation.

The movable part 1b of the core box has been separated from the part 1a by opening the locking device 3, and then raised above the part 1a which remains integral with the transfer plate 2. During this raising operation, some extraction pins, according to a known technique, release the hardened core 27 from the bottom of the cavity 12. As the core 27 has also a counterpart corresponding to the opening 8 of the core box, it remains integral with the part 1b of the box and is raised with it, for example, by means of two magnetic suction cups 28.

The assembly, formed by the suction cups 28, part 1b of the core box and the hardened core 27, is then brought to above a discharge belt 29, and an extractor 30, moving in the direction of the arrow G extracts the core from the part 1b and ejects it onto the belt 29.

The machine for working the above method (FIG. 3) comprises a feed barrel or turret 20, connected to a shot injection barrel fitted, for example, with two shot injection heads 301 and 302. The barrel 30 communicates with the gasification barrel 50 by means of a transfer barrel 40. This barrel 50 comprises four heads of which only three are shown. The boxes pass from the barrel 50 to the barrel for evacuating the cores and cleaning the boxes 70 by means of the transfer barrel 60. The evacuation barrel 70 comprises four core evacuation fittings.

FIG. 3 shows two fittings 701 for boxes with a vertical joint and two fittings 701' for boxes with a horizontal joint. This barrel 70 deposits the cores on the evacuation means 29 which, in the present case, is an endless belt. After removing the cores, the opened boxes pass in front of the cleaning devices 702. The barrel 70 is connected to the feed barrel 20 which brings the boxes 1 back onto the shot injection barrel 30. The feed barrel 20 makes it possible not only to transfer boxes from the barrel 70 to the barrel 30 but also to introduce or bring out boxes with a view to replacing them, so that new cores can be made or for maintenance purposes.

In order to hold the boxes 1 and ensure their movement by means of the barrels 20 to 70, these latter are provided with male parts 110 (operating barrels) or female parts 111 (transfer barrels), having a cavity in the form of a half cylinder 101, 102 designed to receive the front positioning pin 10 of the box and a rear area, set back, 103, 104 designed to receive the rear positioning pin 10. The cavities 101, 102 define a cylindrical housing with a vertical axis enclosing the front positioning pin of the boxes, when the parts 110 and 111 are opposite, the projecting part 105 of the part 110 entering into the cavity 106 of the part 111. In this position, the set-back parts 103 and 104 define an oblong slit of width corresponding substantially to the diameter of the rear positioning of the boxes.

By reason of this oblong slit it is possible to use boxes of variable length, the front cavity 101, 102 positioning the box and the rear cavity 103, 104 supporting the rear pin of the box. Each barrel head comprises the parts 110, 111 described above and the heads of two successive barrels are provided respectively with a cavity 106 and a part with a projecting portion 105. As is known, the boxes pass from one barrel to another in the contact area between two barrels, that is, near a straight line passing through the two axles of two barrels.

The assembly of barrels is driven by a driving unit 80 in which the motor 801, by means of a transmission means 802, drives a distribution box 803 which is connected to each barrel by a transmission shaft 804 with a cardan 805. This driving arrangement based on a driving unit 80, consisting of the members 801, 802, 803, 804 and 805, has a certain number of advantages enabling in particular the construction of a general framework for the machine to be avoided, which facilitates the construction and assembly of this machine.

The assembly of the "shot injection" barrel 30 is shown, in FIG. 4, as a partial axial section. This barrel comprises two working stations (FIG. 3), each provided with an "injection head" 301-302, of type known and which, therefore will not be shown in detail on the drawings. Each of the "injection heads" 301-302 is supplied with a moulding mixture from a movable hopper 303, the latter itself being fed by a fixed hopper 304. Each injection head terminates toward its base by means of an injection plate 305 designed so that it bears on the upper face of the core box. On the sides of the injection plate parallel to the diameter of the barrel passing through the center of the box, are provided two spring push rods 306, whose role will be explained later.

The barrel itself consists of a welded base of 307 which contains the reducer 308 of which the entry shaft 309 is connected to a cardan 805 of the driving unit 80, and of which the exit shaft carries the pinion 310.

On the base 307 is mounted a fixed crown 311 on which, by means of roller bearings 312, the barrel as such 313 revolves, being rotated by the pinion 310 engaging with the toothed crown 310'. The body of the barrel 313 supports the barrel plate 314 on which are mounted the female positioning parts 111, the arrangement and role of which for moving the core boxes 1 and their transfer plates 2 have been described above.

An intercalated structure 315, placed above the plate 314, supports the two injection heads 301, 302.

A jack, 316, which for example can be pneumatic, called "clamping jack" is placed under the core box and enables the latter to be lifted and pressed against the injection plate 305. Compressed air is supplied to the jack and to the injection heads from a fixed duct 317, of a rotary joint 318 and of ducts 319, 320 carried along by the barrel in its movement.

This "injection shot" barrel operates in the following way:

A core box 1 is introduced by a feed barrel 20 and is taken over by the parts 111.

The clamping jack 316 then raises the box and presses it firmly against the injection plate 305. During this movement, the ends 3a, in the form of a hook, of the locking device 3 of the core box are pressed against the spring push rods 306 which ensures that the box is locked.

The "injection shot," that is, the operation that fills the core box with the moulding mixture, is then fired, whereupon the core box is lowered again by means of the jack 316, and is then free. The box is then discharged in the known fashion onto the transfer barrel 40.

These two injections heads 301, 302 can be different so as to be adaptable to two types of different boxes following each other successively onto the shot injection barrel, each of the two barrel stations being allocated to one of the two types of boxes.

In order to facilitate such adaptation, the height of the injection plate can be adjusted by means of packing plates 321.

FIG. 4 shows the core box which has a joint in a vertical plane. But the box could just as well be a box with a joint in the horizontal plane, whether only one of the two types of boxes is used alone, or the two types of boxes alternatively succeed one another on the shot injection barrel, each of the two stations of this barrel being allocated to one type of box.

A box sensor 322 prevents the injection shot being fired in the absence of a core box.

The various operations of this cycle are controlled, for example by valves with control rollers carried by the barrel 30 and moving before the fixed cams. These control devices, being known, are not shown.

The transfer barrel 40 comprises three stations 401 provided with parts 111 with a cavity 106. The gasification barrel 50 (FIG. 5a) is described hereafter in relation with a head 501 for the gasification of boxes having a vertical joint. The heads 501 are fixed on a support cylinder 502 which is driven in a rotary movement around the bearing 503 by means of the toothed crown 504 engaging with the exit pinion 505' of the reducer 505 transmitting the movement of the cardan shaft 804. The cylinder 502 also bears on the crown 506 resting on the assembly plate 507 which bears on the base 509. The reducer 505 is fixed to the base 509 provided with a protective plate 510. The reducer 505 is defined in accordance with the speed at which said barrel must revolve to meet the requirements of continuous kinematic operation.

The assembly plate 507 also carries a gasification cam 510, a vertical clamping cam 511, a sweeping cam 512 as well as a guide guard 513 for the positioning pins 10 of the transfer plates 2 of the core boxes 1. Each gasification head 501 is connected to support cylinder 502 by a bracket 514; this bracket 514 is provided with an angle bracket 515. This angle bracket carries the vertical clamping jack 516 connected to the gasification plate 517. This gasification plate is designed to come into contact with the upper surface of the box 1. To ensure that this box is closed, the gasification plate 517 comprises two push rods 518 which bear on the end 3a of the locking device 3 of the box 1. In addition, the angle bracket 515 carries a sensor 519 for detecting the presence of a box thereby preventing setting off an operation in the absence of a box.

As shown schematically, the gasification plate 517 is provided with a gas feed inlet 520 and exit 521.

The bracket 514 also carries a clamping distributor 522, a catalysing gas distributor 523 and a sweeping gas distributor 524. The catalysing gas distributor 523 and the sweeping gas distributor 524 are connected to the gas feed inlet 520 by means of ducts which are shown simply, in schematic form. The clamping distributor 522 controls the vertical clamping jack 516. The course of this jack is regulated in accordance with the type of box that is used, by means of the regulating means 525.

The distributors 523, 524 are respectively connected to a rotary joint 525 for the catalysing gas and to a rotary joint 526 for the compressed air constituting the sweeping gas. The rotary joint 525 is connected, by its hose 527, to a catalysing gas supply station. The connection between this rotary joint 525 and the distributor 523 is made by means of a duct 528.

Lastly, the gas exit 521 of the box is connected to an evacutation chamber 530 which itself is connected to a suction station 531, not shown, by means of a rotary joint 532.

Each gasification head comprises some distributors 522-524 which are controlled by the cams 510 to 512 by means of the box sensor 519. The rotary joints 525 and 526 are connected to each of the gasification heads. As the cams 510 to 512 are fixed, they control the gasification operation at a point defined by the rotation of the barrel 50.

The duration of the gasification and the sweeping operation also is regulated by the cams 510 and 512.

FIG. 5B shows a simplified plan view of the gasifcation head illustrated in FIG. 5A. This Figure shows in particular the guard plate 513 and the positioning of the box 1 and the positioning pins 10 with respect to the part 110. In this Figure, will also be noted the angle bracket 515 and the upper part of the clamping jack.

The gasification barrel 50 comprises four gasifcation stations (see FIG. 3) identical to the station described above.

As in the case of the shot injection barrel, the four stations can be provided with the same type of core box or alternatively with boxes of two different types, the diametrically opposed stations on the gasification barrel than being provided with the same type of boxes.

The steps in the operation of the gasification barrel 50 are as follows:

Introduction and take over of the upstream box brought by the transfer barrel 40.

Vertical clamping by means of the jack 516 bringing the gasification plate 517 onto the core box.

Introduction into the box of the hardening gas during a period of time regulated by a timing device.

Sweeeping by compressed air.

Unclamping and raising of gasification head.

Discharge of core box onto the downstream transfer barrel 60.

The construction of the barrel 70 for ejecting the cores and cleaning the boxes is slightly different if boxes with a vertical joint are concerned (FIG. 6a) or boxes with a horizontal joint are concerned (FIG. 6b).

According to FIG. 6a, the barrel 70 comprises a barrel 702 having a bearing and resting on the roller members analogous to those of barrel 50. The means for driving in a rotary movement are also analogous and, for this reason, will not be described in detail.

The barrel 702 is provided with a bracket 703 carrying the equipment 701. This equipment consists in an angle bracket 704 which carries a horizontal guide bar 705, supporting a slide piece 706. This slide piece is controlled by the jack 707. The slide piece 706 itself carries a so-called "raising" jack 708 for raising the movable half box 1a, as described hereafter.

The raising jack 708 cooperates with the arm 709 articulated on the cover 710 which is integral with the sliding piece 706. The arm 709 carries, at its end, magnetic suction cups 711 which engages the side of the half box 1a. The other half box 1b is integral with the driving plate 101.

In addition, the equipment 701 comprises a mechanical unlocking jack 712 for the boxes. This jack is fixed on the angle bracket 713, integral with the bracket 703. It acts on the arm 3b of the unlocking device 3 of the core boxes (FIG. 1a).

Lastly, the equipment 701, described above, comprises control means which will be described subsequently.

The equipment 701 operates as follows:

After the box 1 has been transferred from the barrel 60 to the barrel 70 and, more particularly, to the equipment 701, the unlocking jack 712 acts on the arm of the locking hook of the two half boxes 1b and 1a, in order to unlock these two halves. The raising jack 708 then lowers the arm 709 to bring the magnetic suction cups 711 onto contact with the half box 1b. During the third phase the opening jack 707 pushes the slide piece 706 transmitting its movement to the arm 709 to separate the half box 1b from the half box 1a by translation.

When the box 1b is sufficiently disengaged from the box 1a, the raising jack 708 is actuated and this makes the arm 709 rock to bring the half box 1b into a horizontal position which is also shown, above the core discharge belt 9. The ejectors of the half box 1b are then actuated and the core deposited on the discharge belt 29.

Following this, as FIG. 3 shows better, the half boxes 1a and 1b pass in front of the cleaning nozzles 702 from which compressed air is supplied, to remove all traces of foundry sand. After cleaning, the jack 708 is actuated resulting in the lowering of the arm 709, whereupon the jack 707 is actuated to bring the half box 1b against the half box 1a. Raising the rod of the jack 712 results in the locking of the box which is then ready for a new moulding cycle. As the transfer of the boxes is made on a horizontal plane, it is necessary to disengage the arm 709 at the moment of its transfer from the barrel 7 to the barrel 8, as FIG. 3 shows, along a line between the centers of the two barrels.

As before, the control of the various operations as described above, is effected with a number of fixed cams on the framework of the barrel.

According to the invention, provision has been made for a lowering cam 713 and a raising cam 714 of the arm 709. The cams 715 and 716 serve respectively for controlling the closing and the opening of the boxes by means of the jack 707. The cams 717 and 718 control the jack 712 to ensure respectively the locking and unlocking of the boxes by mechanical means.

Lastly, the cam 719 controls the magnetic suction cups 711 while the cam 720 ensures the ejection of the cores.

FIG. 6a includes also a certain number of cams which have been given the general reference 721. These cams serve to control the equipment 701' for boxes with a horizontal joint. As the corresponding operations for the equipments 701 and 701' are themselves passage points of the equipments, the sets of cams are in the same place. It has been found that it is sufficient to provide particular cams corresponding to the cams 713 to 716 and 720. The cams 717 to 720 being the same in both cases.

The various jacks are supplied with a driving gas, such as compressed air, from a source of compressed air (not shown) and a rotary joint 722. The rotary joint is connected to an assembly of distributors (not shown) which are controlled by the cams 713 to 720. The magnetic suction cups 711 are demagnetised by means of the collectors and the brushes 723.

The equipment 701' for boxes with a horizontal joint 1 (FIG. 6b) is fixed to a bracket 703, which is integral with the part 702 of the barrel. This bracekt 703 comprises an angle bracket 704' which has a guide bar 705', which is horizontal, for the transfer operation. A slide piece 706', controlled by a transfer jack 707' enables the upper half box 1b to be brought to the position represented by a broken line in the left part of FIG. 6b.

The equipment comprises, in addition, a raising jack 708' of the half box 1b. The front end of the piston rod of this jack comprises some magnetic suction cups 711' which act on the upper part of the half box 1b.

Finally, an unlocking jack 712' is provided which, when it is actuated, pushes in the arm 3b of the locking hook 3 and frees the upper half box 1b (see FIG. 1b).

The operation of the equipment 701 is very close to that described above in relation to a box with a vertical joint. In the present case, the operating procedure is even simpler. Thus first, the unlocking jack 712' is actuated, then the raising jack 708' is lowered followed by the actuation of the magnetic suction cups 711'. The jack 708' is then raised to bring it into the position represented by a broken line. The transfer jack 707 is then actuated which causes the raised assembly to execute a translatory movement to bring it into the position represented by the broken line. In this position, the upper half box 1b is above the core discharge belt 29. As previously, the ejectors are actuated in order to remove the core from the half box 1b.

After the core has been removed from the half box 1b the cleaning operation of the half boxes is carried out, as shown above, whereupon the half box 1b is brought back onto the half box 1a and the assembly locked together.

To execute the above operations, use is made, as before, of a certain number of cams which in part are common with those in an installation for boxes with a vertical joint. Use is therefore made of an entry transfer cam, an exit transfer cam 713', 714', a lowering cam and a raising cam 715', 716' of the upper half box 1'a and finally the previously described cams 717 to 720.

As in FIG. 6a, it is seen that in FIG. 6b a certain number of cams have the general reference 721' and these cams are intended for the control of the equipment 701 described above. Lastly, as before, there is a compressed air feed with a rotary joint 722' connected to distributors, not shown, and lastly to means for demagnetising the suction cups, which also are not shown.

By way of an example, a machine corresponding to the above description has been made for the production of foundry cores of medium size (maximum weight 5 kg).

In this machine, the shot injection barrel comprises two working stations, each of which has an injection head with a capactiy of 5 liters. The shot injection barrel rotates at a speed of 10 revolutions per minute.

The gasification barrel comprises 4 working stations each constituted by a gasification head. The rotational speed of this barrel is 5 revolutions per minute.

The barrel for evacuating the core and cleaning comprises four equipments. The rotational speed is 5 revolutions per minute. The motor drive unit rotates the distributor at a speed of 1,500 revolutions per minute.

The technical characteristics of this machine are as follows:

Hourly operational rate 1 200 injection shots Number of boxes in circulation 12 Type with vertical or horizontal joints Maximum dimensions of the core height: 250 mm box length: 450 mm width : 250 mm Maximum core weight 5 kg Filling principle Shot injection Capacity 5 liters of prepared sand Hardening Gasification with TEA or DMEA in gaseous phase Blow through and sweeping: air Release of core Extraction and ejec- tion onto belt Preparation of core boxes Provided for in auto- matic cycle: clea- ning and application of mould release product Floor area required about 20 m2

The adoption of continuous kinematic movement for the production of foundry cores, apart from the general advantages associated with kinematic principles, contributes here an additional important advantage which is the improvement of the yield of the machine as the performance of commercially available injection and gasification heads improves.

The principle of continuous kinematics can be defined and described, in its general form, in the following manner (FIG. 7a ):

Given that a determined operation is to be carried out on an object "O" by means of a working station P (an operation which requires a time "T" and has to be carried out at a rate of "R" operations/minute), it is always possible to find a kinematic arrangement which, applied to the station "P" and to the object "O" enables a yield "R" to be obtained, whatever the values of "R" and "T" may be.

The kinematic arrangement illustrated by the diagram, generally consists in:

on one hand, providing a number "N" of stations "P" on the peripheral of the barrel which rotates uniformly at the rate of "n" revolutions per minute,

on the other hand, making the objects "O" follow a circular trajectory identified -- during a portion of the circumference corresponding to an arc ".alpha." -- with the circular trajectory of the stations "P", the tangential speeds of "O" and "P" being strictly equal.

The result of this arrangement is that, at any point of the arc ".alpha.," the relative speed of the object "O" and the station "P" is nil. All the time which the object "O" takes to describe an arc ".alpha." is then available to enable the corresponding station "P" to carry out the operation concerned.

The time taken to describe the arc ".alpha." must be at least equal to "T." Thus for the smallest arc:

T = .alpha./360 .times. 1/ n min.

From which is derived, since the yield "R" = N .times. n, after eliminating n that:

R = N/T .times. .alpha./360

It is seen that when a working station is well defined by T, n and .alpha., the yield is directly proportional to the number of working stations N on the barrel.

If T is large or if the working station is improved by the reduction of the operation time, the yield of the barrel can be improved by increasing "n" (maintaining the value of N and .alpha.) in a proportion very inversely with the decrease of T.

The utilization of continuous kinematics for the production of foundry cores -- in which the object "O" is the core box and the station "P" is either an injection head or a gasification head, or a station for extracting cores -- therefore seems to be completely justified when the performance of the injection and gasification heads improves by the reduction of the operation time.

As FIG. 7b shows, the object is introduced and distributed in the vehicle 1a, which constitutes the first operation.

Operations 2a, 3a, 4a, 5a on the various barrels, shown schematically, are then carried out. the object is discharged at 6a.

Claims

What is claimed:

1. A machine operable in a continuous kinematic manner for the production of foundry cores with the aid of core boxes, the machine comprising a rotatable feed barrel for receiving such boxes, a rotatable shot injection barrel for filling the boxes with a moulding mixture, a rotatable hardening barrel for hardening the moulding mixture in the boxes to form cores, a rotatable barrel for ejecting the cores from the boxes and cleaning the boxes, means for receiving ejected cores from said last-mentioned barrel and conveying them away, driving means for continuously rotating all of said barrels in synchronism, and means for transferring the boxes from each of said barrels to the next barrel in succession in a closed circuit in which said ejecting and cleaning barrel transfers cleaned empty boxes to said feed barrel for recirculation in said circuit.

2. A machine according to claim 1, including a transfer plate for each core box, two positioning pins projecting from the bottom of each plate, and means on said hardening barrel for delivering a hardening gas to the core boxes, each box comprising a first part secured to one of said transfer plates, a second part normally engaging said first part but separable therefrom, releasable locking means mounted on said first part for normally locking said second part to it, the box having internal walls forming a moulding cavity between two auxiliary cavities, said walls being provided with openings connecting said cavities, and screens in said openings, said second part of the box having an opening for filling the moulding cavity with moulding mixture, and the box having openings for circulating said hardening gas through all of said cavities.

3. A machine according to claim 1, said transferring means including a rotatable transfer barrel between said shot injection barrel and said hardening barrel, a rotatable transfer barrel between said hardening barrel and said ejecting and cleaning barrel, means operatively connecting said driving means with said transfer barrels for continuously rotating them in synchronism with the other barrels, and means carried by the transfer barrels for receiving and transferring filled boxes from the shot injection barrel to the hardening barrel and from the latter to the ejecting and cleaning barrel.

4. A machine according to claim 3, in which each transfer barrel and the adjoining barrels are provided with heads that substantially engage each other periodically as the barrels rotate, each pair of engaging heads having a vertical opening between them formed by registering recesses in the two heads, and said machine including a transfer plate on which each core box is mounted, and a positioning pin projecting from the bottom of the plate and disposed in said vertical opening as the plate transfers from one barrel to another.

5. A machine according to claim 11, in which the shot injection barrel includes injection heads, pneumatic jacks for raising the core boxes up to said heads, means for delivering compressed air to said jacks and to moulding mixture in said injection heads, and means including fixed cams for controlling said compressed air delivering means during rotation of the shot injection barrel.

6. A machine according to claim 1, in which said hardening barrel includes a plurality of gasification heads having vertically movable control jacks with plates at their lower ends, means controlled in accordance with the rotational position of each head for delivering fluid pressure to its jack to press the plate against the top of a core box, and means controlled by fixed position cams cooperating with the rotating barrel for distributing a hardening gas and a purging gas to each of said heads.

7. A machine according to claim 1, in which said ejecting and cleaning barrel comprises separate fittings each including means for unlocking a two part core box, means for gripping one part of the box, means for moving said gripping means to move the gripped part of the box containing a core to a position above said conveying means, means for ejecting the core onto the conveying means, means for then returning said gripping means to close the box, and fixed control means for said unlocking and gripping and moving means with which said fittings cooperate as the barrel rotates.

8. A machine according to claim 7, including means for supporting said gripping means, a jack for moving said supporting means horizontally, and a jack carried by said supporting means for raising and lowering the gripping means.

9. A machine according to claim 7, including a slide, a jack for moving the slide horizontally, an arm having an upper end pivotally connected to the slide on a horizontal axis, the lower end of the arm carrying said gripping means, and a raising jack for swinging the arm upwardly over said conveying means.

10. A machine according to claim 1, in which said driving means include a motor, a speed reducing unit driven by the motor, and a separate drive operatively connecting each of said barrels with said unit for independent rotation of each barrel, said barrles being positioned around each speed reducing unit in a closed loop.