EP0377546A1 - Combination of devices for automatically producing casting moulds for flat casting using binder-free sand - Google Patents

Abstract

Combinations of devices permitting, in an automatic system, the production of flat-casting moulds, using a dry binder-free sand, composed essentially of: -devices for scraping (7) and sweeping (8) the sand, using the transfer movement of the chassis between 2 operating stations and producing a flat-mould bottom in the same plane as the edge of the chassis and clearing the tops of the tool parts which have to emerge in order to facilitate the subsequent cutting-out of the closure film, associated with supplementary devices for cleaning and recycling the excess sand. -a device (6) for unrolling/cutting/positioning the sheet of plastic closure film, equipped with a sliding frame making it possible to pass through the arms of an apparatus for demoulding/transferring half-moulds. -a transfer truck (19) and gates (p3) permitting the production of manual finishes outside the moulding zone. <IMAGE>

Description

The present invention, relating to foundry, relates to a set of devices allowing the production, in an automatic system, of molds for flat casting using a bonding sand according to the process known as vacuum molding.

Foundry molds are traditionally made according to this process in 2 parts consisting of a lower half-mold and an upper half-mold which after assembly contain the molding imprint.

A model plate comprising the shape of the half-impression is placed on a box connected to a vacuum source; the whole forms a closed volume and the surface of the model plate is porous or pierced with fine holes connected to the surface bottom of the plate.

A heated plastic sheet is then placed on the model plate where it is thermoformed and follows the shapes of the model plate under the effect of the suction through the holes or the porosity of the model plate; model plate coated with its plastic sheet called contact plastic is placed a frame, consisting of a bottomless box whose inner side walls are porous to air and impermeable to sand; the frame is then filled by gravity with sand natural dry without binder up to the level of its upper surface, with vibration during filling to ensure good densification of the sand.

A second sheet of plastic, called closing plastic, of a size slightly larger than the interior section of the chassis, is then placed on the upper surface of the sand, on the side opposite the imprint.

The connection of the chassis to a source of vacuum then ensures cohesion by tightening the grains of sand in the volume delimited by the contact plastic sheet, the interior walls of the chassis and the closing plastic sheet.

This assembly (chassis, sand, plastic sheets for contact and closure) which remains compact as long as the chassis is connected to a sufficient vacuum source, constitutes the half-mold, the shape of the half-imprint being given at the start during thermoforming of the contact plastic sheet on the model plate placed on the box.

The union of the 2 half-molds, as in the other Casting Casting processes in compacted sand in chassis, constitutes the mold, a mold which remains compact due to the clamping effect of the sand between the impression sheet and the closing sheet if the mold chassis are permanently connected to a source of vacuum.

The advantages which result from the process are well known: strong reduction in noise nuisance compared to green sand clamping processes, very simplified sand circuit and almost total recovery of the molding sand without any operation other than sieving and possible cooling. .

As with the other chassis molding methods, 2 molding and filling methods can be carried out, each having advantages and disadvantages, depending on the orientation of the contact plane of the half-cavities when filling the metal or liquid alloy cavity, contact plane commonly called molding joint.
- either molds for "standing flat-casting molding", which means that in the standby position before filling with the liquid alloy, the molding joint is vertical and the openings in the cavity for filling and for parts which should open into the atmosphere (vents, weights) are in the plane of the molding joint.
- or molds for "flat molding-flat casting", the molding joint in the waiting position before filling then being horizontal (or slightly inclined relative to the horizontal if the mold is placed, for technical reasons of braking or acceleration of the liquid metal in certain parts of the cavity, on an inclined plane) and the openings in the cavity for filling and for the parts which must open into the atmosphere are then located on the surface of the half upper mold, where the closing plastic sheet is placed, the axis of the pouring descent and of the openings of the cavity which must lead to the atmosphere is then perpendicular to the molding joint.

The choice between the 2 methods, which each have their advantages and disadvantages, is guided by technical considerations related to the shape and size of the parts, the nature of the alloy, the degree of automation of the molding process; in the In the case of vacuum molding, the advantages and disadvantages between flat casting and standing have a part in common with the other sand clamping methods and specific features specific to the method of clamping sand by vacuum.

In the case of "standing flat-casting molding", the production of the imprint is facilitated by:
-the possibility of obtaining, in the vast majority of cases, the shape of the "appendages" such as funnel and descent of casting, vents, weights, directly "naturally" during the thermoforming of the plastic contact sheet, this shape being integrated into the shape of the half-impression on a model plate.
the absence of openings in the imprint opening on the lateral surfaces of the mold in the casting position, surfaces which are the upper surfaces of the chassis during molding.

The chassis must have an inclined side wall or with fixed openings (in the case where the funnel and downpipe and appendages always open out in the same place) in order to allow the corresponding parts of the impression to open out during filling.

As with the other conventional methods, the floor area occupied by a standing cast mold is smaller than for a flat cast mold, which allows, with equal production capacity and casting rates, to have clearly cast surfaces more reduced.

The shape of the surface on which the closing plastic sheet is pressed does not have to be precise and flat since it has no functional role of bearing on the surface of the floor of the pouring area; it will usually be in an automatic installation with filling hopper lids as described in European patent ^No. 0014226B1, that resulting from the end of the operation that is a juxtaposition of small sand domes.

The chassis must, however, have, in addition to their internal surface which is porous to the air and impermeable to sand and in the case of the closure of the surface opposite to the imprint by a sheet of plastic - the most common arrangement and pretending to be easier to automatically fill the sand with a hopper in an automatic installation - hollow sand-tight and air-permeable tubes arranged transversely parallel to the surface opposite the molding footprint in order to ensure sufficient cohesion of the sand when the mold is in the casting position, standing, to resist the lateral pressures resulting from the weight of the sand and the thrusts of the alloy during filling; this arrangement of tubes does not allow the separation of sand-piece-chassis traditionally called shake with a process as simple as that described in the patent application ^No. 8,807,324.

The mold must also be kept permanently connected to the vacuum source, even after filling and solidification of the metal and as long as the mold is standing in the filling position to avoid the fall of the sand: the mold must be permanently connected to the source of vacuum until complete separation of the chassis-solidified part-sand.

This arrangement causes, with identical production capacity and rates of casting, an oversizing of the vacuum production unit compared to molds cast flat where the mold, while awaiting its resumption for release, can be disconnected from the source of vacuum as soon as the piece is sufficiently solidified without risk of falling sand which is retained in the volume between the ground of the pouring area and the interior walls of the frames.

When the size or shape of the parts to be produced, their massiveness or large thicknesses and / or the nature of the alloy to be cast - and particularly in the case of steel - requires a high rate of weighting of the supply system to obtain during the solidification removal of healthy parts without porosities, which frequently imposes large weights, the "flat molding - standing casting" method is limited because the size of the weight sections is very often greater than one of the dimensions of the lateral section of the chassis.

These last 3 drawbacks (more complex release system due to the presence of transverse tubes in the 2 chassis parts, large sizing of the vacuum production plant due to the maintenance under vacuum of all the molds present on the casting area - before filling, during filling and after filling, limits on the parts to be produced in the event of massive parts and / or alloy grades requiring a high rate of weighting) lead to prefer the second system called "flat molding - flat casting".

Another advantage of "flat molding - flat casting" using the clamping of the sand by the vacuum effect is the possibility of removing the connection of the mold with the vacuum source as soon as the part is sufficiently solidified, both for Save on the sizing of the vacuum production plant and its energy consumption, but above all because the sand is no longer hardened by the vacuum tightening effect, the cooling accompanied by a contraction shrinkage of the metal often critical with nuances of alloys such as special steels and / or with parts having massive parts connected to each other by thinner parts, shrinkage generating defects called "oric shrinkage" in a mold whose sand remains rigid until 'to the stall, is then carried out in a refractory but not rigid medium which accompanies the dimensional withdrawal without upsetting it.

With the "flat molding - flat casting" system in vacuum molding, the frames do not need transverse tubes, at least in the lower frame in contact with the ground of the casting area, which allows the use of a simple shake-out system and generator of advantages such as that described in patent application ^No. 8,807,324.

On the other hand, the production of the imprint, in particular in an automatic system where the manual interventions must be, for reasons of productivity and safety, limited in duration and carried out at specific locations, is more complex:
-the bottom of the lower half-mold, part in contact with the ground of the casting area, must be flat and in the same plane as the surface of the upper edge of the chassis, this in order to be able to remove the bond of the mold at the source of vacuum as soon as the part is partially solidified without causing localized deformations of the mold and therefore possibly of the part.

-the 2 surfaces of the upper half-mold - half-cavity and top- must be accessible to an operator after demolding and before re-molding with the lower half-mold in order to be able to carry out manual finishing operations, the most important of which are cutting the closing plastic sheet to the right of the impression parts which should open (funnel and descent of casting, vents, weights) with recovery of the forms of tool used to make these impression parts, these imprint parts being in fact impossible to obtain naturally either because they are strongly undercut relative to the direction of demolding or also because they would most often lead to too strong a stretching of the plastic film of contact during thermoforming on the model plate causing the film to tear.

During this operation, the parts of impression having to open must, to ensure the cutting of the plastic of closure without defects and the recovery of the tools, to be visible and not covered with sand, even in very thin thickness.

For these reasons of greater complexity of making the imprint, the automatic systems existing to date for molds cast flat were hampered in productivity due to the need for operator intervention in the molding area or the degree automation was lower than on standing mold installations.

The present invention describes a set of simple devices making it possible, in an automatic system for molds cast flat, to carry out the operations described above with manual intervention limited to the strict minimum for reasons of productivity and in an area where demoulding is completed and where these operations do not stop the continuation of other automatic molding operations.

This set of devices allows:
-the automatic installation, without any manual intervention, of the lower half-mold with its perfectly flat bottom and in the same plane as the lower edge of the chassis on an automatic transfer equipment accessible to operators outside the molding area for finishing operations such as removal of cores, identification marking on imprint, recovery of removable parts of undercut models, etc.
-access, in complete safety and before re-molding, to the 2 surfaces, half-cavity side and top side, of the upper half-mold for the operations of recovering the shapes and tools used to make the emerging parts of the cavity (lowering casting, weights, vents) with total visibility of the parts of the closing plastic sheet to be cut, a sheet which, at the places to be cut, rests on sand-free surfaces; this access before re-molding allows other advantageous operations to be carried out such as the possibility of nailing cores in the upper half-mold, recovery of demountable parts of undercut models, thus greatly simplifying the technical design of the shape of the impression compared to the final shape of the part to be obtained.

These devices, integrated into a complete automatic molding assembly, include:
-a scraping system systematically eliminating, before removing the closing plastic sheet and whatever the type of half-mold to be produced, the sand in excess on the surface on the side opposite to the half-cavity thus making it possible to produce a half - lower mold with flat bottom in the same plane as the lower edge of the chassis.
-a sweeping system, posterior to the scraping system, which acts in the case of the top of an upper half-mold to remove excess sand on the tools making the imprint forms which must open, sweeping carried out before removing the closing plastic sheet; the upper plastic sheet will therefore rest on sand-free surfaces where it is to be cut.
-a device unwinder-cutter-installer of the closing plastic sheet passing between the arms of the release device-transport of half-molds and / or chassis; this device automatically performs the removal of the synchronized closing plastic sheet with the request of the demoulding-transporting device for half-molds and / or chassis - a trolley provided with a lifting table for removing the lower half-mold, comprising 2 automatic vacuum connections and associated with a set of automatic gates , allowing the completion of finishing operations on the lower half-mold outside the molding area and outside the working area of the demolding-transporting device for half-molds and / or chassis.

-a device for cleaning excess sand redeposited on the vibrating table during scraping and / or sweeping operations and a device for recovering all excess sand after filling of the chassis and recycling in the chassis filling hopper.

According to an advantageous but nonlimiting embodiment, the scraping systems, sweeping the top of the upper half-mold, cleaning the vibrating table are partially static and use the automatic relative movement of transfer of the chassis between its position at the position of filling-vibration and its position at the demolding station.

A preferred but nonlimiting exemplary embodiment is described in more detail with reference to the accompanying drawings.

The accompanying drawing Figure ^No. 1 shows, in top view, a schematic and simplified general arrangement of the molding system and the status of different devices of the present invention.

In this drawing, the assembly marked 1 is a carousel with 4 stations, each station being able to carry a box (or "Vacuum Box") with a model plate placed on it; this arrangement is very commonly adopted in molding preferably in d '' other transfer systems because it allows simultaneous work at each station when the carousel is stopped and simultaneous transfer from one station to the next operating station during the rotation of the carousel, which ensures maximum productivity provided that times at each station are adjacent, with a simple transfer movement ensured by rotation.

When the carousel is stopped at the end of the transfer, each station occupies a position corresponding to one or more predefined operations.

The position marked a corresponds to a station where the boxes carrying model plates and connected to the vacuum network by a set of sheaths connected upstream on a rotating joint passing through the center of the carousel, can be extracted from the carousel thanks to a table elevator identified 2 fitted with rollers controlled and transferred to a trolley identified 3 located outside the carousel to facilitate the operations of preparation-tool change, setting up of the parts used for the impression forms which should open up for the upper half-mold (casting, weights, vents, ...).

The movable frame of the device identified 4 used for the removal of the contact plastic sheet when the box is on the station a comes in the position of removal directly above the station a.

The position marked b corresponds to a position where the demolding-transfer device for chassis and half-molds identified 5 comes to deposit a chassis.

The position marked c corresponds to a station where the filling and vibration of the sand of the half-mold takes place, thanks to a vibrating lifting table which raises the box-plate-model-chassis assembly to press it against the flexible joint of the bottom of a filling funnel marked 12 of the type object of the patent ^No. EP 0014226B1.

The position marked d corresponds to a station where the closing plastic is applied by the unwinder-cutter-installer device of the closing plastic film sheet, device marked 6, and the removal of the half-mold by the device identified 5.

The assembly marked 7 corresponds to the device for scraping excess sand from the lower or upper half-molds (part of sand above the upper level of the chassis).

The assembly identified 8 corresponds to the sweeping device for removing excess sand from the tools of the upper half-molds used to produce the parts of the imprint which must open (pouring down, weights, events, etc.).

In Figure ^No. 1 also schematically:
-the upper edges of the hopper of the excess sand recycling device, identified 11.
- part of the fixed security barriers preventing access to the carousel in automatic mode, marked 18.
-the carriage marked 19 used for the transport and transfer of the half-molds and complete molds.
-the set of automatic gates marked p3 to allow access to operators:
.on the lower half-mold or on the complete mold when the carriage 19 is outside the deflection zone of the device marked 5.
.on the upper half-mold, held by the device marked 5 and presented in a vertical position excluding the carousel, for finishing operations on the 2 surfaces of the upper half-mold.

The accompanying drawing Figure ^No. 2 corresponds to a given lateral and simplified schematic sectional view I-II of the accompanying drawing Figure ^No. 1.

In this diagram, the vibrating elevating table is identified 9, the identified assembly 10 fixed on each of the arms of the carousel box supports corresponds to the device for cleaning excess sand dropped on the vibrating table, and the identified assembly 11 represents the device for recycling excess sand in the spotted filling hopper 12.

The arrow pointing to the x mark shows the connection of the rotating joint of the carousel to the source of vacuum.

The accompanying drawings FIGS ^No. 3,4,5 represent the identified devices 7 and 8 in more detail: Figure ^No. 3 is a top view of the two devices 7 and 8, Figure 4 a side view of two devices in action after cutting along an axis perpendicular to the pivot axis 7b.

In this figure ^No. 4, the two devices are shown in action and the upper part of a frame is represented, the mixed dashed lines indicating the shape of the upper surface of the sand domes succession before striking said sheet metal of the seventh identified device 7, then plane and in the same plane as the upper edge of the chassis after leveling, then plane and slightly below the plane of the edge of the chassis and releasing the upper parts of the mold which should open after scanning by the brushes 8a of the device 8.

The arrow shows the direction of advance of the chassis during the transfer rotation of the carousel from station c to station d.

Figure 5 is a partial section along the axis of the marked part 8b of the device marked 8 showing the details of the up-down system of the active part of the device 8 and of the level adjustment as well as the fixing of the active part on the lifting device; the double arrow in this figure corresponds to the arrival or the bleeding of the compressed air for inflation or deflation of the inflatable stops 8e.

According to a preferred but non-limiting embodiment, the device marked 7 as a whole consists of 2 metallic connecting pieces marked 7a each articulated around an axis marked 7b and provided with return springs marked 7c.

The metal part marked 7a carries 2 rounded parts marked 7d, fixed on the part 7a by screws; the fixing position of the parts 7d is adjustable on the part 7a thanks to lights cut out on the parts 7d, the axes of the tightening screws parts 7d on parts 7a passing through these lights.

When the fixing position of the parts 7d on the parts 7a is correctly adjusted, the walls of the chassis come, at the start of the transfer rotation of the carousel from the position marked c to the position marked d, in contact with the rounded parts of the parts 7d of so that the edges of the chassis push back without catching the metal parts 7a upwards by rotation around the axes 7b.

On the 2 pieces marked 7a is fixed a sheet of shape marked 7e having an inclined part, sheet whose lower vertical level which constitutes the edge of the attack blade for leveling-scraping the sand is identical to the part of the rounded shapes pieces 7d coming into contact with the edges of the chassis at the start of rotation.

When the device marked 7 is in action the angle of inclination of the inclined part of the sheet marked 7e with respect to the horizontal plane of the upper edge of the chassis moving towards the sheet is greater than 90 °, in order to prevent, in combination with the return torque of the springs marked 7c, the push of the sand to lift the metal part 7e above the level of the upper edge of the chassis during rotation.

The length of the part 7e is calculated so that, during the transfer rotation from station c to station d, the entire upper section of the chassis, including the thickness of its edges, is in contact with the leading edge of the part 7th.

The return torque of each of the springs is adjustable by means of adjustable stops, fixed one on the support structure of the bearings of the axis of rotation (stop marked 7f) and the other on the part marked 7a (stop marked 7g) .

A third adjustable stop marked 7h, fixed on the support structure limits the low position of the mobile assembly 7a-7d-7e before the chassis comes to bear on the parts 7d at the start of rotation, in order to ensure that the contact of the chassis is done well on the rounded parts of the 7d parts without hooking.

According to a preferred but non-limiting embodiment, the device marked 8 as a whole consists of a set of brushes with fairly rigid plastic trim (type "broom stick") marked 8a threaded in a solid and rigid metal profile marked 8b and blocked at the 2 ends of the profile by a quick blocking device marked 8c advantageously consisting of an eccentric cam actuated by a lever; this device marked 8c allows disassembly and very rapid exchange of used brushes without any tools.

The metal profile is fixed at its 2 ends to 2 plates marked 8d; these plates 8d are fixed on the upper part of inflatable stops marked 8e, inflatable stops whose base is fixed on a metal support marked 8f.

Threaded rods marked 8g, fixed by a set of locknuts marked 8h on the upper plate 8d, and which can slide through bores drilled in the metal support 8f of the inflatable stops carry sets of locknuts -nuts marked 8i and 8d.

The locknuts identified 8i limit the descent of the assembly 8a-8b-8d when deflating the stops and the locknuts identified 8j limit the up stroke of the same assembly when inflating the stops so as not to not damage these stops.

These locknuts 8i associated with threaded rods 8g make it possible to easily adjust the lower level of the brush lining when the stops are deflated and that the device marked 8 is therefore in the working position and to compensate for use with overall wear of the brush linings; the amount of swept sand varying approximately linearly, increasing from the end closest to the side of the chassis closest to the center of rotation of the carousel at the other end, a periodic reversal of the 'profiled assembly 8b and its brushes 8a ensures almost constant wear of the linings of all the brushes and consequently a change of brushes at low frequency taking into account the useful length of lining, which allows costs of maintenance of the device identified 8 particularly low.

The mobile assembly supported by the inflatable stops has a significant weight in order to ensure a sufficient sweeping force; the inflatable stops, which require no maintenance, have a stroke of a few centimeters, limited by the locknuts identified 8i and 8j adjustable on the threaded rods 8g, sufficient so that when they are inflated the low level of the brush linings is above the upper plane of the frame and when they are deflated the low level of the linings is below the upper plane of the 1 to 2cm chassis.

Depending on whether the chassis which has just been filled at station c before transfer corresponds to a lower half-mold or to an upper half-mold, the upper chassis plane constitutes in the first case the underside of the lower half-mold and in the second case the top of the upper half-mold.

In the first case, only the device identified 7 is actuated, the device identified 8 being in the high position by inflating the stops, and the sand is therefore leveled off at the same level as the plane of the upper edge of the chassis before fitting the closure plastic. which will provide a lower half-mold with a flat bottom in the same plane as the edge of the chassis.

In the second case, the 2 devices marked 7 and 8 are actuated, the device marked 8 being in the low position by deflating the stops; during the transfer rotation, the part of excess sand above the edge of the chassis - the most important part - is first removed by the device marked 7 then the device marked 8 sweeps a weak layer of sand of 1 at 2cm thus releasing from sand the upper parts of the recoverable or non-recoverable tools used to make the imprint forms which must open (weights, downpipe, vents), these upper parts of the tool must necessarily be located slightly below the level from the upper edge of the chassis to avoid being damaged at the start of the filling operation at station c, when the vibrating lifting table presses the vacuum box-plate-model-chassis assembly under the filling hopper, the edges of the chassis coming into contact with the flexible seal at the edge of the filling hopper.

When, during the transfer, a tool for an impression form which has to open comes into contact with the brush linings, the linings are flexible enough to be repelled by the tool and only dry natural sand without binder on top of the tool is removed by scanning.

The assembly being commanded and controlled by an automatic control which knows by identifying each arm of the carousel the type of half-mold which has just been filled at the station c-types of half-molds which always succeed one another in half order - lower mold - upper half-mold for the same mold - the order to deflate the stops is only given for an upper half-mold and the high or low position of the metal profile marked 8b is controlled by inductive proximity detectors spotted 8k; the order of rotation of the carousel ensuring the transfer from station c to station d will be subject - among other conditions - to checking the correct position of the profile marked 8b according to the type of half-mold concerned by this transfer.

At the end of the transfer rotation, the sand leveled by the device identified 7 and swept by the device identified 8 if it is an upper half-mold falls by gravity largely into the hopper of the recycling device identified 11 and partly on the vibrating elevating table then in the low position; the part of sand fallen on the vibrating table is then expelled at the end of the transfer rotation in the hopper of the recycling device identified 11 by the identified device 10 consisting of a set of brushes of the same type as those of the device identified 8, fixed under each of the 2 side members of each of the 4 positions of the carousel.

During the filling-vibration operation of the next half-mold, the lifting table being rid of the sand before the start of the filling-vibration operation, this operation can be carried out without difficulty, which would not have been the case. if the sand partially fallen on the vibrating lifting table during the previous scraping or scraping-sweeping operation had remained there.

According to a preferred but nonlimiting embodiment, the rest of the recycling device identified 11 consists of an emitter of the "pneumatic dense phase transport" type which redirects the recovered sand to the filling hopper, by the driving force of the air. compressed, through a closed pipe; this arrangement is chosen in preference to other sand transfer systems to preserve the advantages of low noise and dust nuisance of the process and taking into account the nature of dry sand without binder which lends itself advantageously to this transport technology.

The accompanying drawings in FIGS. 6,7 and 8 show the unwinder-cutter-installer device for the closing plastic sheet, identified 6 as a whole, in more detail.

Figure ^No. 6 is a top view of the entire device 6, the slide frame detected 6a is completely released position for removal of the closure sheet of plastic on the frame of the mold half at the station, chassis marked CH.

Figure ^No. 7 is a side view along section II of the device 6, and shows the enlarged detail of the types of profiles carrier sheets identified 6b, 6c, 6d and 6e.

Figure ^No. 8 is a view along section II-II showing the sliding frame marked 6a passes between the side portions of the apparatus 5 shown when this unit is in position for taking the frame CH of the mold half in position ; the arrows directed towards the mark x on the partial sectional view of the apparatus 5 in FIG. 8 correspond to the connection towards the source of vacuum; the apparatus marked 5 is of the same type as that described in the patent application of invention ^No. 7504686.

According to a preferred but non-limiting embodiment, the device 6 consists of a sliding frame marked 6a provided at its 2 ends with square tubes "sheet carriers" marked 6b and 6c.

The frame 6a translates horizontally thanks to 4 bearing rollers marked 6f rolling on the horizontal parts of 2 U-shaped support profiles marked 6g; the 4 rollers marked 6f ensure the maintenance of the frame, even when the latter is in the extreme exit position as shown in Figures 6 and 7, the support of the front rollers on the upper wings of the profiles marked 6g compensating for the overturning torque of the part of the frame outside the supports 6g.

A pair of boxes with double balls marked 6n fixed on the lateral wings of the frame 6a provide lateral guidance of this frame, each ball bearing on the internal vertical walls of the support profiles 6g.

The frame 6a is driven in translation by 2 chains marked 6h each fixed by 2 quick fasteners on a part integral with the lateral parts of the frame 6a; each of the 2 chains meshes with 2 toothed pinions, one motor the other ensuring the tension of chain; the 2 drive pinions marked 6i are supported by an axis marked 6k passing through 2 bearings fixed on the top of the support profiles 6g; a 2-direction motor of rotation marked 6l causes the axis 6k to rotate.

At the other end of the support profiles marked 6g, an axis marked 6m passing through 2 fixed bearings on the top of the profiles 6g carries the 2 non-driving pinions completing the chain mechanism for the drive in translation in the 2 directions of the frame marked 6a. .

By convention with respect to Figures 6 and 7, when the frame goes from right to left, the movement is an advance or exit and if the frame goes from left to right it is said to move back or inward .

2 "carrier" tubes marked 6d and 6e can go up or down together by a few centimeters thanks to their connection at the 2 ends by threaded rods marked 6q to plates marked 6o each surmounting an inflatable stop marked 6p.

The principle of ascent-descent of these 2 carrying tubes 6d and 6e is identical to the system of inflatable stops ensuring the movements of ascent-descent of the profile marked 8b of the device 8: securing of the movements of ascent-descent of the plates 6o and the tubes 6d and6e by the threaded rods 6q; the threaded rods can slide through bores made in the support part 6r of each inflatable stop and sets of locknuts identified 6s and 6t respectively limit the low position and the high position carrier tubes 6d-6e.

The strokes and the upper and lower extreme positions are easily adjustable by moving the sets of locknuts 6s and / or 6t. When the 2 support tubes 6d and 6e are in the high position, they come into contact either with the unwound plastic film or with the support tubes 6b or 6c of the frame 6a depending on the stop position of the frame 6a.

Between the 2 tubes 6d-6e is placed a heating-cutting wire marked f consisting of a fine wire of resistant alloy stretched between 2 insulating supports marked 6u fixed on the external lateral parts of the 2 support profiles 6g; the insulating supports 6u allow adjust the mechanical tension of the heating wire, its position in height, and receive the arrival on terminals of the electric cables supplying the heating wire; when it is in service, the heating wire is supplied with electric voltage of Safety 24V.

The horizontal level of the heating wire f is adjusted so that it is located between the high and low positions of the 2 tubes 6d-6e.

At the end of the profiles marked 6g, axis side 6m of support for non-driving pinions, a set of 2 metal parts marked 6v each provided with 2 free rollers marked 6w allows the roll of plastic film supported by its marked axis to be put in place 6x; a tension bar marked 6y is fixed under the profiles 6g, near the parts 6v.

Each of the 4 carrying tubes 6b, 6c, 6d, 6e is made up, as shown in detail G, of a tube of square or rectangular section, closed to the 2 ends and drilled with a large number of small holes on its active face which is the underside for tubes 6b and 6c and the top face for tubes 6d and 6e; at the edge of the active faces are welded 2 square bars, just at the limit of a longitudinal row of holes.

Each tube is connected individually and autonomously, through rigid pipes then flexible taking into account the movements that each tube can travel, to a motorized 3-way valve which can connect the interior volume of the tube either to the source of general vacuum or to the atmosphere (3-way valves / motorized respectively labeled 6b1 for the carrier tube 6b, labeled 6c1 for the carrier tube 6c, labeled 6d1 for the tube 6d and 6e1 for the tube 6e).

When a roller end is applied to the active face of a carrier tube and the latter is connected to the vacuum network, the film, pressed by suction, is held by the carrier tube which, if it moves carries with it the thin plastic film; the role of the 2 bars is to considerably reinforce the peel resistance of the film from the active face of the support tube if the film is pulled perpendicular to the direction of movement of the support tube.

The cycle of the entire device 6 in automatic operation is described below.

When a new roller is placed on its supports 6v, the frame 6a is in the retracted position in the support profiles marked 6g so that the support tube 6c is slightly to the left of the tension bar 6y for a lateral view as FIG. 7; the end of the roller is manually unwound for a few centimeters by passing it over the tension bar marked 6y until it comes to apply on the active face of the tube 6c; a signal given to the automation by pressing on a push button then puts the tube 6c in connection with the vacuum source; then a second press on the same push button controls the start of the cycle.

The frame 6a advances by rotation of the motor 6l until the tube 6c, still connected to the source of vacuum, is in line with the tube 6e, which ensures the unwinding of the film up to the level of this tube.

The different stop or slowdown positions of the frame 6a are identified by inductive proximity sensors fixed in an adjustable manner on one of the 2 support profiles 6g and which detect the passage of a metal pallet integral with the frame 6a (detectors and pallet not shown in the accompanying drawings); likewise the high or low (adjustable) positions of the 2 tubes 6d-6e are controlled by detectors inductive proximity switches not shown but arranged similarly to the detectors marked 8k of the device marked 8.

The 2 tubes 6d-6e which were at rest in the low position are then mounted by inflation with compressed air of the 2 stops 6p so that the active face of the tube 6e comes into contact and bears on the active face of the tube 6c; when the automation has controlled this support (upper position of the tubes 6d-6e), the tube 6e is connected to the vacuum network by its motorized valve 6e1 and simultaneously the tube 6c, by operation of its valve 6c1 is returned to the atmosphere .

After the expiry of an adjustable time delay known as the "decompression" time delay intended to allow the vacuum in the tube 6c to cancel out completely, the inflatable stops 6p are purged of their compressed air and the 2 tubes 6d-6e come back down, the tube 6e being still linked to the source of vacuum; this first phase therefore ensured the unwinding of the plastic film roll up to the 6th and the maintenance of its end held by the tube 6th, in order to avoid operators having to access the area 6d-6e which is above the moving parts of the carousel, which is not the case for the tube 6c at the start of the cycle and the roller supports 6v.

The replacement of a finished roller and the replacement of a new roller can therefore be done without intervention in dangerous areas, therefore without stopping any automatic cycle of the other equipment.

The frame 6a moves back until the tube 6b is perpendicular to the tube 6e; the 2 tubes 6d-6e go up and when they are in the high maintained position, the upper active face of the tube 6e is supported on the active face of the tube 6b; the tube 6b is then connected to the vacuum source while the tube 6e is placed in the atmosphere; after expiration of the "decompression" delay, the 2 tubes 6d-6e are lowered the tube 6b being always connected to the vacuum source which ensures the recovery of the terminal part of the roller.

The frame 6a before then, causing the unwinding of the roll, until the distance between the tube 6a and the heating wire f represents the length of sheet necessary to cover the frame of the half-mold. (the cut-out length is slightly greater than the internal dimension of the chassis in position d which is perpendicular to the direction of translation of the frame 6a, the width of the roller being it slightly greater than the other internal dimension of the chassis).

The frame 6a is then stopped, the tube 6b still connected to the vacuum source, the 2 tubes 6d-6e mount together by inflating the stops; when the 2 tubes are in the high maintained position they are simultaneously connected to the vacuum source by action of their 2 motorized valves 6d1 and 6e1, which presses and tightens the part of plastic film between the 2 tubes, the heating wire f is then energized, then after a so-called "preheating" delay corresponding to an activation sufficient temperature of the wire, the 2 stops are deflated, the wire being always under tension and the tubes 6d-6e connected to the vacuum network.

During the downward movement of the 6d-6e tubes, the stretched film of thin plastic comes into contact with the heated wire which ensures the cutting by fusion; when the 2 tubes 6d-6e have arrived in the low position, the power supply to the heating wire is interrupted.

There is then a plastic sheet held between the tubes 6b-6d still connected to the vacuum source, the new end of the roller being held by the tube 6e still connected to the vacuum source.

When the half-mold is in position d with the device marked 5 in position for picking up the half-mold, a signal is sent by the device management automation 5 to the device management automation 6; the tube 6d is then returned to the atmosphere, the tube 6b remaining connected to the vacuum source, after the expiration of the "decompression" delay, the frame 6a advances to its extreme exit position corresponding to the tube 6b plumb with the side portion of the chassis furthest (= leftmost in Figure ^No. 7), which ensures by sliding on the half-mold the establishment of the closure sheet of plastic film.

As soon as the frame 6a has arrived in this position, the tube 6b is returned to the atmosphere and a signal is sent simultaneously to the automation of the device identified 5 which then puts the chassis of the half by its vacuum sockets -mold in connection with the vacuum network.

The closing plastic sheet, as soon as it is released by the tube 6b, is thus pressed onto the top of the half-mold by the effect of atmospheric pressure; after the expiration of the "decompression" delay, the frame 6a moves back to that the tube 6b is perpendicular to the tube 6e, which completely releases the frame 6a from the rising vertical trajectory of the chassis and of the device identified 5 during demolding.

If the vacuum level in the chassis, controlled by a vacuum switch on the vacuum circuit of the device marked 5, between its vacuum sockets and its motorized valve for connection with the vacuum source, is then sufficient, the demolding of the half -mould by the device identified 5 can be done.

The cycle of the device identified 6 is frozen until the half-mold and the device 5 have left the zone of the station d, which is informed to the automatic management of the device 6 by the device management automation 5.

At this stage, the device identified 6 is in the state corresponding to that after fitting and unrolling the new roller up to the tube 6e; as soon as the frame 6a can again come out without risk of striking the identified device 5 or the half-mold it carries, the cycle can start again.

A photoelectric detector (not shown in the appended figures) placed near the tension bar 6y constantly monitors the smooth running of the roll and its presence and therefore detects the end of the roll; when the detector no longer sees the film, the device returns automatically to the starting position and an indicator light signals the end of the roll or the possible rupture of the film to allow operators to restart the cycle after changing the roll or repairing the torn film.

The device marked 5, after complete demolding of the half-mold, transports it by translation beyond the carousel; if it is a lower half-mold, the carriage marked 19 is then in the position shown in FIG. ^o 1 and the device identified 5, after turning the mold half 180 °, deposit this lower mold half on the elevating table, free, of the carriage 19; the carriage 19 puts its lower vacuum connection in connection with the half -mold before the device identified 5 disconnects its vacuum connections; when the device 5 has removed its vacuum connections, it leaves the lower half-mold on the carriage 19, connected to the source of vacuum by the cart empty 19.

As soon as the device 5 is outside the translation path of the carriage 19, the gates p3 located on the path of the carriage 19 open and the carriage 19 advances to a position beyond the gates.

The gates p3 then close, the gate p3 located laterally to the path of the carriage 19 facing this second stop position of the carriage 19 opens, which allows access for finishing work (laying of cores, recovery of parts removable from undercut model, etc ...) to the lower half-mold on carriage 19 but not access to the carousel or to the working area of the device identified 5.

When the operators have finished their work on this half-mold, they withdraw beyond the side door p3 and inform the management automation of the carriage 19 and the doors p3 which then closes the side door p3.At the next quarter turn of the carousel, the half-mold demolded by the device identified 5 is then an upper half-mold; after complete demoulding, the device 5 transports this half-mold beyond the carousel, directly above the initial position of the carriage 19 , then rotates it by approximately 90 ° and lowers it back to working height, then stops all its movements while keeping the half-mold connected to the vacuum network. The set of p3 gates then opens, which allows operators to access the upper half-mold without being able to enter the carousel area which can therefore continue its automatic cycle; when the work on the 2 half-molds is finished (lower half-mold on the carriage 19 in the stopped position opposite the side door p3, working on the upper half-mold held by the device 5 and of which the part on the impression side and the part on the top side are accessible for the operations of cutting the closing plastic sheet, of recovering recoverable tools having been used to make the parts of the impression which must open) the operators withdraw beyond the side door p3 and inform the automatic control.

The side door p3 closes, then the device identified 5 raises the upper half-mold while rotating it 90 ° in the opposite direction to return it to the horizontal; the carriage 19 then returns to its initial position and the rewinding of the upper half-mold on the lower half-mold on the table of the carriage 19 is carried out by the device marked 5, the latter only removing its vacuum connections when the carriage 19 has connected its upper vacuum connection to the upper half-mold. The device 5 then leaves the trajectory zone of the carriage 19 to continue its cycle then the carriage 19, carrying the complete mold kept connected to the vacuum network, returns to its stop position facing the side door p3 ; the gates p3 on the path of the carriage 19 then close while the side gate p3 opens: operators can then safely access the mold on the carriage 19 for finishes such as for example cramping of the 2 half-molds without being able to enter the working area of the carousel and the apparatus 5 which can therefore continue their automatic cycles without problems. When the operators have completed this work, they withdraw beyond the side door p3 and inform the management automation which closes this door and then leaves the carriage 19 to one of its removal positions.

This set of devices therefore allows the realization of a mold for flat casting with a minimum of manual interventions limited to all that is not repetitive and constant and this with maximum productivity since these interventions occur outside the molding area. and / or work of the device identified 5 for transporting the chassis and half-molds therefore do not stop the automatic cycles of these devices.

Claims (2)

1-Set of devices allowing the production, in an automatic system, of molds for flat casting using dry sand without binder, characterized in that they comprise:
-a device for scraping and leveling the sand eliminating excess sand above the upper edge of the chassis; that this scraping device uses the movement of transfer of the chassis between 2 operating stations to carry out the removal of excess sand by means of a form of sheet metal whose leading edge is on the whole frame of the section during the transfer, spotted device 7 as a whole on Figure ^No. 1.
-a scanning device, posterior to the scraping device and acting only for the top of an upper half-mold; that this scanning device can be put into service or retracted by an up-down movement obtained by inflatable stops that this device ensures the removal of the sand above the tooling or imprint parts which should open using the transfer movement of the chassis between 2 operating stations and this before the automatic installation of the closing plastic film sheet; that this device allows the easy subsequent cutting portions of the closure sheet of plastic film corresponding to the lead-through parts of the mold, spotted device 8 as a whole on Figure ^No. 1.
-a device for unwinding-cutting-laying the closing plastic sheet carrying out the automatic laying of the sheet on the half-mold after the scraping and / or sweeping operations thanks to a support tube situated at the end of a sliding frame which can pass through the arms of a demoulder-transport device for half-molds or chassis when this device is in the demold position; the replacement of the plastic film roll feeding this device is done outside the carousel's work area or the mold-conveying apparatus therefore without stopping the automatic cycles thereof, device designated as a whole 6 of figures ^No. 1 and 2.
-a device for cleaning excess sand removed by the scraping and sweeping devices that may have been redeposited on the vibrating elevating table; that this cleaning device consisting of a set of brushes fixed under each of the box carrier beams of the transfer carousel uses the transfer movement to clean the vibrating lifting table; device designated 10 as a whole in Figure ^No. 2.
-a device for recovering excess sand and recycling in the filling hopper characterized by a hopper of upper section dimensioned according to the positions of the scraping, sweeping and cleaning devices, surmounting a dense phase pneumatic transport transmitter in order to keep the method nuisance and its low noise and dust; spotted device 11 as a whole in Figure ^No. 2.
-a device made up of fixed barriers, a transfer trolley provided with 2 vacuum sockets, a set of gates allowing safe access to the lower half-mold and / or to the complete mold on the trolley stopped outside the zone molding, to both surfaces of the upper-side mold-half impression and side above mold for finishing off molding zone; devices identified respectively 18, 19 and p3 in Figure ^No. 1. 2-devices according to claim 1 characterized in that:
the inclined shape of the scraper plate of the scraper device in action prevents any lifting by the sand and that the shaped parts attached to the connecting parts of the sheet to the pivot axes prevent any catching by the chassis during the transfer; tole seventh located and shaped parts identified in Figures 7d ^No. 3 and 4.
-the sweeping device has an easily adjustable level to compensate for the wear of the brush linings thanks to a set of adjustable nuts and locknuts on the threaded rods connecting the brush holder profile with the actuated up-down system by the inflatable stops; that the brushes can be replaced very quickly without any tools thanks to a locking device by eccentric cam secured to a lever at the 2 ends of the row of brushes; game-spotted against nuts nuts 8i and 8j and identified threaded rods 8g in Figures ^No. 4 and 5; spotted locking devices 8c in Figs ^No. 3,4 and 5.
-the depositing device of the closure of plastic sheet comprises a heating wire (marked f in FIGS ^No. 6 and 7) for the cutting length of the fully automatic manner and a sheet end detector monitoring roll or of film breakage or the roll unwinding incident that the frame (identified in figures 6a ^No. 6and 7) of the device does not interfere, in the retracted position, the chassis release movements, which allows the use the half mold transfer device to create the vacuum in the half mold without having to make a connection of the chassis with the vacuum source by another device when removing the plastic film sheet.

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