DE102019134739B3 - Core shooting process and core shooting device for the production of cores with simultaneous hardening process - Google Patents

Abstract

The invention relates to a core shooting method comprising the steps of: a. Inserting a first core shooting tool into a core shooting machine; b. Shooting core molding material and a binder into the first core shooting tool; c. Ejecting the first core shooter tool from the core shooter machine; d. Curing the core in the first core shooting tool; e. Repeat the previous steps with at least one further core shooting tool, the introduction of the further core shooting tool into the core shooting machine parallel to the ejection of the previous core shooting tool from the core shooting machine or parallel to the hardening of the core in the previous core shooting tool. A corresponding core shooting tool is also described.

Description

The invention relates to a core shooting method with a plurality of core shooting tools each having at least two tool contour shells or tool halves that are adjustable between an open position and a closed position, the core shooting tools in the closed position each forming a hollow chamber that is geometrically adapted to a core to be shot. A core shooting process is known, for example, from EP 1626 830 B1 . A similar core shooting method is also known from FR 3 047 429 A1 .

In order to cast complex structural or molded parts, cores are often necessary that can be used in casting molds, for example to form cavities in the structural or molded part. Such cores can be made with core shooting tools. A core molding material made of sand and a binder is usually shot into the core shooting tool. The core molding material assumes the shape of the hollow chamber enclosed by the tool and can then be cured. To harden the core material, a gas can be gassed or flowed through, for example, through the core. Alternatively, there is the possibility of hardening the core by the action of heat, in particular by heating the core shooting tool.

The methods known from the prior art have the disadvantage that the cores in the core-shooting tool remain within the core-shooting machines for hardening and, as a result, high cycle times have to be taken into account for the series production of cores. The core has to be "baked" in the tool until it has a sufficiently thick wall. A further disadvantage is that high curing temperatures are necessary to reduce the cycle times, which, however, increases tool wear.

It is therefore the object of the invention to provide a core shooting method which enables the series production of cores with reduced cycle times.

This object is achieved by the proposed core shooting method according to claim 1. The independent claim 12 relates to a corresponding core shooting tool. Advantageous embodiments of the invention are each the subject matter of the dependent claims.

• Einbringen eines ersten Kernschießwerkzeugs in eine Kernschießmaschine;
• Einbringen von Kernformmaterial und einem Bindemittel in das erste Kernschießwerkzeug;
• Auswerfen des ersten Kernschießwerkzeugs aus der Kernschießmaschine;
• Aushärten des Kerns im ersten Kernschießwerkzeug, , wobei zum Aushärten des Kerns im Kernschießwerkzeug das Kernschießwerkzeug in einen Durchlaufhärteofen überführt wird;
• Wiederholen der vorherigen Schritte mit zumindest einem weiteren Kernschießwerkzeug, wobei das Einbringen des weiteren Kernschießwerkzeugs in die Kernschießmaschine gleichzeitig zum Auswerfen des vorherigen Kernschießwerkzeugs aus der Kernschießmaschine oder gleichzeitig zum Aushärten des Kerns im vorherigen Kernschießwerkzeug erfolgt,
• wobei in jedem der Mehrzahl Kernschießwerkzeuge dieselbe geometrisch angepasste Hohlkammer ausbildet ist.

Accordingly, a core shooting method using several core shooting tools is proposed, which are each adjustable between an open position and a closed position, the core shooting tools in the closed position each forming a hollow chamber that is geometrically adapted to a core to be shot, the method having the following steps:

• Inserting a first core shooting tool into a core shooting machine;
• Introducing core molding material and a binder into the first core shooting tool;
• Ejecting the first core shooter tool from the core shooter machine;
• Hardening of the core in the first core shooting tool, the core shooting tool being transferred to a continuous hardening furnace for hardening the core in the core shooting tool;
• Repeating the previous steps with at least one further core shooting tool, the introduction of the further core shooting tool into the core shooting machine at the same time as ejecting the previous core shooting tool from the core shooting machine or at the same time as hardening the core in the previous core shooting tool,
• wherein the same geometrically adapted hollow chamber is formed in each of the plurality of core shooting tools.

The main advantage of the invention is that, through the use of a plurality of core shooting tools and the ejection of core shooting tools already filled with core molding material from the core shooting machine, one is not only dependent on a single core shooting tool, but can also prepare further core shooting tools for the shooting process in parallel while the first core shooter is still in the machine. On the other hand, there is great potential for time savings in that the hardening process is outsourced from the machine and transferred to a hardening furnace. At the same time, by accepting longer curing times by lowering the curing temperature, the stress on the individual tools or the use of environmentally friendly inorganic binders can be made possible. Worn tools can also be successively replaced by new tools so that an intact core shooting tool is always available and machine downtimes can be minimized.

Before the core molding material and a binding agent are introduced into the first core shooting tool, binding agent can be placed on the inner surfaces of the hollow chamber.

It can be provided that the introduction of a first core shooting tool into a core shooting machine requires the introduction of two Includes tool contour shells and their locking in a closed position by means of a toggle lever device.

In particular, it can be provided that the introduction of core molding material and a binding agent into the first core molding tool comprises: shooting core molding material into the first core molding tool and injecting binding agent into the injected core molding material. This can be done, for example, via an injection device with a plurality of injection nozzles which, after the core molding material has been introduced into the cavity of the core shooting tool, is introduced through corresponding openings in one of the tool contour shell in order to inject binding agent into the molding material in this position. For example, the injection device's binding agent can be introduced via the venting nozzles of the core shooting tool. Alternatively, a device for introducing the binding agent via the vapor or gas phase can be provided.

It can further be provided that the introduction of core molding material and a binder into the first core shooting tool comprises: shooting a core molding material-binder mixture into the core shooting tool. In particular, this can take place via a metering pump that functions according to the endless piston principle, with the binding agent being mixed with the core molding material only in the nozzle tip.

Because the core shooting tool is transferred to a continuous hardening furnace to harden the core in the core shooting tool, the core shooting tool can be left in the furnace until the binding agent has hardened to such an extent that removal can take place. The tool is preferably heated in an oven until a stable outer shell has formed. For example, the oven can be an infrared oven for rapid heating. Alternatively, the core shooting tool can be heated with flames or inductively. When using a cement binder, the humidity in the furnace can be kept at a high level. The oven can preferably have a circulating air device for circulating the air humidity.

Alternatively, the process can also be carried out using gas curing. For this purpose, after shooting, the tool can be placed in a gas-tight chamber instead of in an oven. There the tool is _{rinsed with CO 2} or an amine gas, for example, until the gas has penetrated the entire core. The tool can then be taken out of the gas-tight chamber and opened so that the hardened core can be removed.

It is also conceivable that the method is a mask form or croning process. A binder-covered core molding material can be shot into the core shooting tool. The tool can then be heated in an oven until a stable outer shell has formed, whereby the oven can be, for example, an infrared oven for rapid heating, alternatively the core shooting tool can be heated with flames or inductively heated. In particular, loose material can be emptied from the core in order to improve the gas permeability.

Alternatively, provision can be made for the method to be carried out with cold-setting binders such as slowed-down furan resins, cement binders or gypsum binders. After the core has been fired, the tool can be placed in an oven and left there at a moderate temperature until the binder has hardened to such an extent that it can be removed. In the case of cement binders, the humidity in the furnace can be kept at a high level.

In addition, it can be provided that the method is a cold box method. A particular advantage of a cold box method is the possibility of using lighter tools compared to hot box methods. Furthermore, lower process temperatures can achieve lower wear and a significant cost advantage using hot box processes. It is also conceivable that the method is carried out as a hot box process with inorganic or other hot-curing binder systems.

It can also be provided that the binder is an inorganic binder. A particular advantage of inorganic binders is that they are more environmentally friendly than organic binders and produce less smoke during casting. This reduces the burden on employees due to a reduced development of odors and prevents condensation from forming on the casting tools.

It can be provided that the curing temperature during the curing of the core is less than or equal to 110 ° C., preferably less than or equal to 100 °, particularly preferably less than or equal to 90 ° C. This enables, on the one hand, the use of an inorganic binder and, on the other hand, the use of tool shells made of plastic or less tool wear.

In particular, it can be provided that the core shooting tool is opened after the core has hardened and the hardened core is removed.

In addition, provision can be made for the core-shooting tool to be cleaned after the core has been removed, reset to a condition suitable for shooting, and then reintroduced into the core-shooting machine. Because the cleaning takes place "offline", the duration of this production step can also be deducted from the cycle time. The outsourcing of as many functions as possible from the core shooting machine also has the advantage that the functional scope of the core shooting machine is reduced and this is basically reduced to a simple sand conveying device. By regularly removing the tool from the machine, the tool condition can also be checked at regular intervals, so that the tool condition is fundamentally better. As a result, the cores can be shot at lower pressures, which in turn has a beneficial effect on tool wear and energy consumption. In addition, individual failures of core shooting tools do not lead to a failure of the entire system. In addition, quality assurance measures are easier to implement. It can be provided that the core shooting tools are cleaned at a cleaning station. In particular, cleaning of the shot nozzles and / or cleaning of the shaping surfaces and / or cleaning of the connection, sealing and contact surfaces can take place.

Because the same geometrically adapted hollow chamber is formed in each of the plurality of core-shooting tools, time-consuming conversion processes between the individual core-shooting processes can be avoided. The hardening of the cores may also take more time due to the many identical tool trays available while maintaining the low cycle time. This redundancy through several identical core shooting tools thus enables the outsourcing of the time-consuming steps that do not necessarily have to be carried out within the machine, such as curing, core removal, cleaning and putting them back into a shootable state.

Furthermore, a core shooting tool for carrying out the core shooting process is disclosed, with a first tool contour shell and a second tool contour shell, which can be adjusted back and forth between a closed position and an open position, a hollow chamber geometrically adapted to a core to be shot being formed in the core shooting tool in the closed position , with at least one injection hole for introducing core molding material and / or binding agent into the hollow chamber, and with at least one frame for moving the core shooting tool in and out of the core shooting machine, the frame at least one horizontally and / or vertically supporting support element for receiving having forces acting on the tool contour shells.

For this purpose, at least one closing element can be provided for automated closing, in particular at least two closing clips, which hold the tool contour shells in the closed position. The locking clips can in particular be designed as C-profiles, which encompass the lower and upper tool contour shells and thereby generate a predetermined preload. The C-profiles can be designed to be laterally adjustable, guided by rails. Furthermore, the height of the C-profiles can be adjusted by means of a hydraulic system, so that the profile width can also be adjusted. The locking element can also be designed as a toggle lever locking element mounted on the core shooting tool. Alternatively, it can be provided that the tool contour shells are screwed together.

It can be provided that the tool contour shells each have a wall thickness of less than 20 mm, preferably less than 10 mm, particularly preferably less than 5 mm. The use of thin tool contour shells will have a particularly advantageous effect on material consumption. Thin tool contour shells also have the advantage that the core accommodated in the shells can be brought to the predetermined hardening temperature in the hardening furnace more quickly and with less energy input.

In particular, the tool contour shells can be formed essentially from plastic. So-called "casting copy processes" can be used to manufacture the tools. Plastic has the particular advantage that it can be produced more cheaply and with less energy consumption. Furthermore, the handling is simplified because the tool contour shells have a lower weight. The plastic can have a polymer, for example. The polymer can be, for example, a thermoplastic or a thermosetting plastic. The thermoplastic can have one or more of the following groups: polyamide, polyoxymethylene, polypropylene, polyethylene, acrylonitrile-butadiene-styrene, polyphenylene sulfide, polysulfone, polymethyl methacrylate, polystyrene, polycarbonate, polycarbonate / acrylonitrile butadiene styrene, polyether ether ketone, polyether acryl ketone , Polytetraflourethylene. The thermoset can have one or more of the following groups: polyurethane, cast polyamide, epoxy resin, melamine resin, urea resin, phenolic resin, furan resin.

In addition, a ventilation nozzle can be installed on at least one of the tool contour shells be provided. The tools can alternatively be vented via several nozzles, as no explicit exhaust air ducts are required. On the one hand, the core shooting tool can be vented via the venting nozzles. In addition, it is conceivable that the binding agent is introduced via the ventilation nozzles. Alternatively, special access nozzles can also be provided, via which the binding agent is introduced into the core shooting tool. As an alternative, it is also conceivable that the binding agent is introduced via the injection bore. The binding agent can be introduced into the core shooting tool as an aerosol, in gaseous form or in its vapor phase.

Alternatively, the tool contour shells can be porous or perforated. In the case of tool contour shells of this type, the binding agent can be introduced by a dipping process.

• 1 ein Ausführungsbeispiel eines herzustellenden Gussteil;
• 2 ein Ausführungsbeispiel einer unteren Werkzeugkonturschale;
• 3 ein Ausführungsbeispiel von einem in der Schließstellung mittels Klammer verklammertem Kernschießwerkzeug;
• 4 einen Kernschießvorgang in einem mit einer Klammer versehenen (nicht dargestellt) Kernschießwerkzeug;
• 5 das Erhitzen des geschossenen und verklammerten Kernschießwerkzeugs in einem Härteofen;
• 6 ein beispielhaftes Kreislaufsystem unter Verwendung einer Mehrzahl Kernschießwerkzeuge;
• 7a ein Ausführungsbeispiel, bei dem ein Vorlegen von Binder auf die Innenflächen der Werkzeugkonturschalen;
• 7b das Ausführungsbeispiel gemäß 7a, bei dem nach dem Vorlegen von Binder ein Einschießen / Einfüllen von binderlosem Sand in das Kernschießwerkzeug erfolgt;
• 8a ein weiteres Ausführungsbeispiel, bei welchem nach dem Einbringen von Sand das Einbringen von Binder in den Sand über Entlüftungsdüsen in der unteren Werkzeugkonturschale erfolgt;
• 8b das Ausführungsbeispiel gemäß 8a, bei dem das Injektorsystem über die Entlüftungsdüsen Binder in den Sand einbringt;
• 9 ein Ausführungsbeispiel eines Kernschießwerkzeugs mit einem Seitenschieber.

Exemplary embodiments of the invention are explained with reference to the following figures. It shows:

• 1 an embodiment of a cast part to be produced;
• 2 an embodiment of a lower tool contour shell;
• 3 an embodiment of a core shooting tool clamped in the closed position by means of a clamp;
• 4th a core shooting operation in a clamped core shooting tool (not shown);
• 5 heating the shot and clamped core shooter tool in a hardening furnace;
• 6th an exemplary circulatory system using a plurality of core shooting tools;
• 7a an embodiment in which a presentation of binder on the inner surfaces of the tool contour shells;
• 7b the embodiment according to 7a , in which, after the binder has been placed in front of it, binderless sand is shot / filled into the core shooting tool;
• 8a a further exemplary embodiment in which, after the sand has been introduced, the binder is introduced into the sand via ventilation nozzles in the lower tool contour shell;
• 8b the embodiment according to 8a in which the injector system introduces binder into the sand via the ventilation nozzles;
• 9 an embodiment of a core shooting tool with a sideshift.

1 shows an example for a cast part 16 Sand core to be used, which corresponds to the negative of a section of the inner contour of the cast part. Pouring liquid metal into a mold results in a solid casting without the use of cores 16 . Should the casting 16 but to be hollow for the sake of an intricate geometric construction, e.g. to save weight or to allow media to pass through, there are various methods of achieving this by means of cores produced by the core shooting process. Here, the shape of the cavity to be created is produced with specially prepared molding material. This sand core is then placed inside the mold at the point where the cavity or an undercut is to be created. If necessary, this core can be reinforced with core iron so that it is not destroyed during the casting process.

2 shows a lower mold contour shell 3 showing the lower half of the contour of the sand core 1 maps. The lower tool contour shell 3 each has on their underside, their upper side and on the side walls at least partially level bearing surfaces so that these can be easily placed and moved into the core shooter or that the upper tool contour shell is particularly simple 2 on the lower mold contour shell 3 can be placed or an unproblematic fastening of the mounting brackets 5 for clamping both mold contour shells 2 , 3 is made possible against each other.

A core shooting tool 1 with both tool contour shells 2 , 3 shows in its closed position 3 . The tool contour shells 2 , 3 are placed on top of one another in such a way that inside a cavity that is geometrically adapted to the sand core to be produced 4th is formed. The contact surfaces of the contour shells 2, 3 can preferably be designed in such a way that they have a self-centering function and the contour shells 2, 3 are thereby automatically correctly aligned with one another. For example, the contact surfaces of both tool contour shells 2 , 3 be angled complementary to each other. For example, the contact surface of the lower tool contour shell can be used 3 Angled circumferentially in the shape of a gullet or funnel and the contact surface of the upper tool contour shell 2 be designed accordingly. At the top of the upper tool contour shell 2 is a bullet hole 8th formed over which the core molding material and possibly also the binder in the core shooting tool 1 can be introduced. Two C-shaped brackets grip around the sides from the left and right 5 both halves of the core shooter tool 1 and hold them against each other under a certain pretension.

A core shoot in one with a clamp 5 (not shown) locked core shooting tool 1 is in 4th shown. The core shooting tool 1 is on a carrier plate 7th supported. About this carrier plate 7th is the core shooting tool 1 can also be moved into and out of the core shooter. Above the core shooter tool 1 is a vertically adjustable shooting head 6th shown, which with a corresponding nozzle to the bullet hole 8th docks to the necessary material such as sand and / or binder in the cavity 4th of the core shooter tool 1 shoot in. Closing the tool with clamps 5 or a toggle lever device can take place outside of the machine. Alternatively, both tool contour shells 2, 3 can be introduced separately into the machine and only then closed and clamped together in this. The core shooting tool is made by moving the carrier plate horizontally 7th below the shooting head 6th positioned, the shooting head 6th then moves vertically into the bullet hole 8th and shoots sand and / or binder into the cavity 4th .

Then the core shooter tool 1 including the locking device 5 and the entrapped sand binder mix from the core shooter into a hardening furnace 9 transferred, which in 5 is shown. In the hardening furnace 9 becomes the core shooter tool 1 heated to a predetermined temperature over a predetermined period of time so that the core can harden.

6th shows schematically the sequence of the core shooting process according to the invention for the production of cores with simultaneous hardening process. The course of a core shooting tool is shown 1 through the process. First, a lower and an upper tool contour shell 2, 3 are placed on top of one another in such a way that they have a geometrically adapted cavity inside 4th form. The tool contour shells 2,3 are then by means of clamps 5 fixed to one another under a predetermined bias. Then the core shooting tool prepared in this way is used 1 transferred to the core shooting machine, in which by means of a shooting head 6th over the bullet hole 8th Sand and / or binder in the cavity 4th is shot. The core shooting tool 1 is then placed in the hardening furnace together with the enclosed sand-binder mixture 9 transferred to harden there. After the core has hardened, the core shooting tool is used 1 the hardening furnace 9 removed and both tool contour shells 2, 3 separated from each other so that the core can be removed. The two tool contour shells 2 , 3 are then sent to a cleaning device 10 handed over, in which sand and binder residues are removed and the tool contour shells 2,3 are returned to a shooting condition. Both mold contour shells are then made 2 , 3 prepared to shoot in another core and the cycle begins again. Parallel to the one shown core shooting tool 1 there are several more core shooting tools 1 in the same process, for example 20 pieces, in order to achieve the highest possible utilization of the core shooter. Another core shooting tool 1 is transferred to the core shooting machine as soon as the previous core shooting tool 1 this has left and in turn in the hardening furnace 9 is passed. The hardening furnace 9 is preferably a continuous furnace, which, according to the cycle time of the core shooting machine, the individual subsequent core shooting tools 1 records.

7a shows an alternative embodiment of the invention in which a sand-binder mixture does not enter the cavity at the same time 4th is shot in, but the binder before the mold contour shells are closed 2 , 3 is applied to the inner contour of the cavity halves. The shells are then closed and the core molding material via the injection opening 8th into the cavity 4th shot in, as in 7b shown.

The 8a and 8b show an embodiment of the invention in which the binder neither over the injection bore 8th , is introduced by prior application to the cavity halves, but via a separate injector system 15th , which by means of several injector nozzles 13th optionally via the ventilation nozzles 12th or via additionally provided openings in one of the tool contour shells in the cavity 4th is injected. In this embodiment, the sand is first over the shooting head 6th through the bullet hole 8th into the cavity 4th shot in. Then the injection nozzles 13th of the injector system 15th through the associated holes in the cavity 4th introduced and the binder then injected into the shot sand.

9 Figure 10 shows another embodiment of the core shooter tool 1 , in which the lower tool contour shell 3 and the upper mold contour shell 2 are designed so that they jointly have an additional opening 16 train over which from the outside of the core shooter tool 1 an access to the cavity 4th provided. This opening 16 serves to accommodate a sideshifter 14th . This is done before the sand is shot into the cavity 4th laterally into the cavity 4th retracted and is used to form an undercut contour of the sand core.

The features of the invention disclosed in the above description, in the figures and in the claims can be essential for realizing the invention both individually and in any combination.

List of reference symbols

1

Core shooter tool

2

Upper mold contour shell

3rd

Lower tool contour shell

4th

Geometrically adapted cavity

5

Bracket

6th

Shooting head

7th

carrier

8th

Bullet hole

9

Hardening furnace

10

Cleaning device

11

Injector for binder

12th

Air vents

13th

Injector nozzles

14th

Sideshift

15th

Injector system

16

Casting

Claims (13)

Core shooting method using a plurality of core shooting tools, which are each adjustable between an open position and a closed position, the core shooting tools in the closed position each forming a hollow chamber that is geometrically adapted to a core to be shot, the method comprising the following steps: a. Inserting a first core shooting tool into a core shooting machine; b. Shooting core molding material and a binder into the first core shooting tool; c. Ejecting the first core shooter tool from the core shooter machine; d. Hardening of the core in the first core shooting tool, the core shooting tool being transferred to a continuous hardening furnace for the hardening of the core in the core shooting tool; e. Repeating the previous steps with at least one further core shooting tool, the introduction of the further core shooting tool into the core shooting machine at the same time as ejecting the previous core shooting tool from the core shooting machine or at the same time as hardening the core in the previous core shooting tool, wherein the same geometrically adapted hollow chamber is formed in each of the plurality of core shooting tools. Core shooting process according to Claim 1 , wherein prior to the injection of core molding material and a binding agent into the first core shooting tool, binding agent is applied to the inner surfaces of the hollow chamber. Core shooting process according to Claim 1 or 2 , wherein step b. comprises: shooting core molding material into the first core shooting tool and injecting binder into the injected core molding material. Core shooting process according to Claim 1 or 2 , wherein step b. comprises: shooting a core molding material-binder mixture into the core shooting tool. Core shooting method according to one of the preceding claims, wherein the method is a cold box method. A core shooting method according to any one of the preceding claims, wherein the binder is an inorganic binder. Core shooting method according to one of the preceding claims, wherein the hardening temperature during hardening of the core is less than or equal to 110 ° C, preferably less than or equal to 100 °, particularly preferably less than or equal to 90 ° C. Core shooting method according to one of the preceding claims, wherein the core shooting tool is opened after the core has hardened and the hardened core is removed. Core shooting process according to Claim 8 , wherein the core shooting tool is cleaned after the core has been removed, reset to a shootable state, and then reintroduced into the core shooting machine. Core shooting tool for carrying out the core shooting process according to one of the preceding claims, with a first tool contour shell and a second tool contour shell which are adjustable back and forth between a closed position and an open position, with a hollow chamber geometrically adapted to a core to be shot being formed in the core shooting tool in the closed position is, with at least one injection bore for injection of core molding material and / or binding agent into the hollow chamber, and with at least one frame for moving the core shooting tool in and out of the core shooting machine, the frame having at least one horizontally and / or vertically supporting element for absorbing forces acting on the tool contour shells, the tool contour shells each having a wall thickness of less than 20 mm , preferably less than 10 mm, particularly preferably less than 5 mm. Core shooter tool after Claim 10 which furthermore has at least one closing element for automated closing, in particular at least two closing clips, which holds the tool contour shells in the closed position. Core shooting tool according to one of the Claims 10 or 11 , wherein the tool contour shells are formed essentially from plastic. Core shooting tool according to one of the Claims 10 to 12th , wherein a ventilation nozzle is provided on at least one of the tool contour shells.

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