CLAMPING DEVICE FOR A CORE BUNDLE AND METHOD FOR CASTING

Description

This application claims priority to European patent application no. 24174579.3 filed on May 7, 2024, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a clamping device for a multi-part core bundle made of a molding material and to a method for casting using a clamping device and to a core bundle of this kind, the clamping device comprising at least one clamping mechanism by means of which the core bundle is subjectable to a clamping force on opposite contact surfaces of the core bundle.

DESCRIPTION

Such clamping devices and methods are sufficiently well known from the prior art and are regularly used to produce complex casting mold parts, such as engine blocks or the like. A core bundle is then formed from a plurality of cores, which are disposed in a shared composite and together form a casting mold. The clamping device is then used to fix the cores or the core bundle together in their bond and to press them together using a clamping force. When a melt is poured in the casting mold, considerable mold filling pressures arise which require external support of the core bundle in addition to the fixation of the individual cores of the core bundle together in order to prevent relative movements of the cores as a result of the mold filling pressure as far as possible and to ensure the dimensional stability of the casting mold. In order to ensure this external support of the core bundle, it is known, for example, to dispose core bundles in box molds which have a molding-sand filling adapted to an external contour of the core bundle. However, this requires the operation of a box-mold installation with which a box mold having a corresponding molding-sand filling must be provided for each individual core bundle, which results in high operating costs.

A clamping device for a multi-part core bundle is known from DE 10 2006 010 798 B3, in which the cores are inserted into a box mold and can be clamped or braced against each other within the box mold by means of several clamping mechanisms. In particular, the core bundle is designed having a mold slope onto which the box mold is pushed, thus generating the clamping force. The core bundle is wedged with the box mold and the clamping force is applied indirectly via cylinders which push the box mold onto the core bundle.

The disadvantage here is that the core bundle must always be adapted to the size of the box mold and a large number of box molds are required to operate a casting installation for the continuous production of products. Converting this casting installation to products which require a core bundle of a different size means that all the box molds have to be replaced. The consumption of molding material is also very high if the product is significantly smaller than the existing box mold. The core bundle must then be made larger than would actually be required to cast the product. This is also the case if the product to be cast has a geometry which differs significantly from the square or rectangular shape of the box mold. In this case, unusable areas of the box mold must be filled with molding material.

SUMMARY

It is therefore the object of the invention to propose a clamping device for clamping a multi-part core bundle, a casting mold and a casting installation as well as a method for casting using a clamping device, all of which enable a simple and inexpensive production of different products.

The clamping device according to the invention for a multi-part core bundle made of a molded material comprises at least one clamping mechanism by means of which the core bundle is subjectable to a clamping force on opposite contact surfaces of the core bundle, the clamping mechanism having at least two clamping modules by means of which the clamping force is exertable on the core bundle, the clamping modules each having a clamping element for abutting against one of the contact surfaces of the core bundle, the clamping elements being moveable independently of each other with respect to contact surface.

The core bundle is made of a number of cores, which in turn consist of core sand consolidated using a binder material. Preferably, the entire core bundle is then formed from this core sand, which makes it easier to reuse the core sand in line with a casting installation. The core bundle is preferably used for casting products made of metal, for example cast iron, cast steel, gray cast iron, aluminum, other non-ferrous metals or alloys thereof. In principle, however, it is also possible to use the core bundle for casting hardenable materials made of casting compounds, for example concrete, polymers or the like.

To clamp the core bundle, it has at least two contact surfaces which are essentially opposite each other so that the clamping force can be exerted on the core bundle via these two contact surfaces. The clamping force is generated via the clamping mechanism, which exerts the clamping force on at least one of the contact surfaces. The opposite contact surface can then abut against a thrust bearing of the clamping device, which can be essentially rigid, i.e., immovable. Since the clamping mechanism has at least two clamping modules having a clamping element for abutting against one of the contact surfaces, the clamping elements can be moved independently of each other with respect to the contact surface. The core bundle can then be designed in such a manner that the contact surface on which the clamping mechanism acts with the clamping force is formed from at least two partial surfaces which are spaced apart from each other. In this context, the partial surfaces can be positioned at different distances relative to the clamping mechanism when the core bundle is braced using the clamping device. The ability to move the clamping elements independently of each other by means of the clamping modules means that the clamping modules can be individually adapted to the different partial surfaces. The clamping force is then exerted on the partial surfaces by the clamping modules. The core bundle can then be designed in such a manner that the core bundle is adapted to the geometry of a product to be cast and the contact surface forms a ledge or several ledges, for example. This makes it possible to save on molding material when manufacturing the core bundle, as the core bundle then no longer has to be formed or filled with molding material to the extent that it lies completely straight against a clamping mechanism with the contact surface, as is the case with a mold box. In addition, the independent movability of the clamping elements enables the clamping mechanism to be used for a wide variety of core bundle types. For example, a ledge in the core bundle facing the clamping mechanism can be more or less deep or not present at all. This allows universally using the clamping device for different types of core bundles. Converting a casting installation to a different product then no longer necessarily requires a change of all clamping devices or mold boxes of the casting installation. Overall, products can be produced more cost-effectively by casting.

The clamping device can comprise at least two clamping mechanisms, which can be disposed opposite each other with respect to the contact surfaces of the core bundle. The clamping force can then be exerted on the core bundle onto the contact surface of the core bundle by both clamping mechanisms from opposite sides of the clamping device. The clamping mechanisms can each have two clamping modules, so that the core bundle can have contact surfaces on both sides which are formed from partial surfaces. For example, at least one ledge can then be formed between the partial surfaces on each of the opposite contact surfaces of the core bundle. The contact surfaces or partial surfaces can then be formed in parallel. This makes the clamping device even more flexible to use for core bundles of different products.

The clamping device can comprise at least one further clamping mechanism by means of which the core bundle can be subjected to a further clamping force on further contact surfaces of the core bundle, the further contact surfaces being able to be transverse, preferably orthogonal, with respect to the contact surfaces. It is therefore intended for the further clamping mechanism to exert the further clamping force on an upper side or an underside of the core bundle. If, for example, the core bundle is designed having a square or rectangular basic shape, at least three lateral surfaces of the core bundle can form the contact surfaces. Furthermore, the core bundle can be braced on one circumference, i.e., on all lateral surfaces, by means of the clamping device. In principle, the core bundle can then be formed having a contact surface on all sides, a clamping force being able to be applied by means of the clamping device on the contact surface.

The clamping device can have a clamping frame, which can surround the core bundle at least partially, preferably entirely, the clamping modules being able to be fastened on the clamping frame. The clamping frame can be ring-shaped or frame-shaped and completely surround the core bundle. The clamping modules can then be fastened to the clamping frame and thus exert the pressure force on the core bundle. The clamping modules can be detachably fastened so that the clamping modules can be disposed on the clamping frame as required, adapted to the core bundle in question. They can be fastened using a screw connection. The clamping frame can be formed by an upper frame and a lower frame, the clamping modules then being able to be disposed between the upper frame and the lower frame.

The clamping mechanism can comprise at least three, four, five, six or more clamping modules. The number of clamping modules may depend on the number of partial surfaces of the contact surface. A clamping module can then be provided for each partial surface. However, it is also possible for a clamping module to act on two partial surfaces of the contact surface if the partial surfaces are formed in a shared plane and at the same relative distance from the clamping module in question. It is also intended for clamping modules to remain unused if the core bundle to be braced is comparatively small and does not completely extend along a row arrangement of all clamping modules of the clamping mechanism. Overall, the clamping mechanism can be used more flexibly with a higher number of clamping modules.

The clamping module can have a spindle stock having a guide and a spindle mounted on the spindle stock and drivable using a manipulator, the clamping element being moveable along the guide towards the contact surface using the spindle. The guide can extend orthogonally with respect to the contact surface so that the clamping force can be exerted towards the contact surface. The spindle can be driven by means of a manipulator, which means that a rotation of the spindle can cause a movement of the clamping element along the guide towards the contact surface or in an opposite direction. The manipulator can be formed by an electric motor with or without gearing, for example an electromechanical screwdriver, or can also have a plurality of electromechanical screwdrivers. In this case, each of the clamping modules can also have such a manipulator. However, to further reduce costs, the manipulator can also be stationary and separate from the clamping device as a component group or a station of a casting installation. The manipulator can then consist of an electromechanical screwdriver for driving the spindle or of a plurality of screwdrivers for simultaneously driving all the spindles of the clamping module. In this case, a screw head or socket wrench can then be formed on the spindle of the clamping module, the manipulator being able to engage on the screw head or socket wrench when a clamping device is positioned on the manipulator for bracing the core bundle. The corresponding manipulator can drive the spindle until the desired clamping force is achieved. Furthermore, it may be intended that a contact plate is fastened to or on the clamping element and essentially forms a plane surface which corresponds approximately to a partial surface of the contact surface. This results in an advantageous distribution of the force generated by the clamping module on the contact surface or partial surface. Undesired breakage of the core bundle as a result of uneven force distribution can thus be effectively prevented. Optionally, two or more clamping elements can be equipped with a shared contact plate. This is possible if the partial surfaces of the contact surface are essentially formed in a shared plane.

At least one spring mechanism can be formed on the clamping element, the clamping force being exerted on the contact surface by means of the spring element. The spring mechanism makes it possible to compensate for dimensional tolerances of the core bundle. In addition, the spring mechanism can form a comparatively precise degree of the clamping force. A spring characteristic curve of the spring mechanism can be selected such that further adjustment of the clamping element in the direction of the core bundle does not result in a significantly greater clamping force. The spring mechanism can be formed by a tension spring, compression spring, leaf spring, Belleville washer or preferably a Belleville washer package. A clamping element can also be fitted with a number of spring mechanisms. This allows the clamping module to be particularly compact.

The clamping device can comprise a support which can form a support surface for the core bundle, at least the clamping mechanism and/or the clamping frame being able to be disposed on the support. It is then possible to first form the core bundle by assembling cores on the support before the core bundle is clamped using the clamping mechanism or the clamping frame. Once the core bundle has been assembled, the clamping mechanism or clamping frame can then be disposed on the support. This makes it possible to initially form the core bundle without the possibly interfering clamping mechanism or clamping frame and also to handle it by means of the support. The support can also be designed in the form of a frame or a rack so that the support can be easily transported by means of conveyors. This is particularly advantageous if the core bundle has a large weight, for example between 100 kg and 1000 kg. Projections can be formed on the support and corresponding recesses can be formed on the clamping mechanism or clamping frame, or vice versa. These can be designed in such a manner that the clamping mechanism or the clamping frame can be positioned or centered in a form-fitting manner without the clamping mechanism or the clamping frame being firmly connected to the support. The clamping mechanism or clamping frame then rests loosely on the support and can be fixed to a support surface by weight alone. The clamping mechanism or clamping frame can thus be connected to and removed from the support particularly easily and quickly. This can be done easily using a crane or another conveyor device, for example.

Posts can be disposed on the support in order to support the core bundle. It may be provided that the clamping modules are disposed in such a manner that the clamping elements can be positioned in spaces formed between the posts. The posts can advantageously prevent the core bundle from tipping over on the abutment when the support is transported with the core bundle and also ensure that the core bundle does not fall off the abutment together with the product after being filled with liquid metal, when the core bundle cools and breaks open, if the clamping mechanism or the clamping frame has already been removed.

The clamping device can comprise a trough, which forms a receptacle for the support, the support being able to be inserted in the trough. The trough can be easily transported by means of a conveyor device, for example industrial trucks or the like, and can accommodate the support in such a manner that the trough at least partially surrounds the support.

In particular, the trough enables simplified transportation of the support with the core bundle and, if required, with the clamping mechanism or the clamping frame on the core bundle. After a cavity of the core bundle has been poured out and the clamping frame or clamping mechanism has been removed, a binder of the molding material can burn, which can lead to the core bundle disintegrating. The molding material can then also fall from the support into the trough during transport of the core bundle in line of a casting installation and be collected there. After removing the support from the trough, the molding material located inside can be collected and easily reused in a process.

The casting mold according to the invention comprises a clamping device according to the invention and a core bundle, the core bundle being clamped on opposite contact surfaces of the core bundle in the clamping device.

The respective contact surface can be made of a plurality of plane partial surfaces, the partial surfaces being able to be disposed in offset parallel planes. The planes can each extend vertically and parallel to the clamping elements or contact elements on the clamping elements. The clamping force exerted on the core bundle is then distributed over a total area of the contact surfaces. A ledge can therefore be formed between the partial surfaces so that the core bundle can be adapted to the geometry of a product and formed using a much smaller amount of molding material. For example, two, three, four, five, six or more parallel planes can be defined or provided, within each of which contact surfaces or partial surfaces can be formed on a core bundle. A number of clamping modules acting on a contact surface then corresponds to at least a number of parallel planes on a core bundle.

The casting installation according to the invention comprises a plurality of clamping devices according to the invention, a manipulator for bracing a core bundle in a clamping device and a conveyor device for conveying the clamping devices along the manipulator, the manipulator being able to actuate clamping modules of the clamping device and clamping elements of the clamping modules being moveable independently of each other on a contact surface of the core bundle and being subjectable to a defined clamping force. The manipulator is therefore positioned stationary, the corresponding clamping devices with the corresponding core bundle being conveyed to the manipulator and being actuated there by means of the manipulator in such a manner that the clamping elements are moved onto the corresponding contact surface of the core bundle. This infeed movement of the clamping elements is then carried out by the manipulator until the defined clamping force is generated. A casting mold is then formed, which can be conveyed to a casting machine. The conveying device can be formed here by an industrial truck, a conveyor belt or another suitable device for conveying such casting molds. In particular, cyclical conveying can be intended.

The clamping devices can each comprise at least one clamping mechanism, the clamping devices having differing clamping mechanisms. The clamping devices are then also designed differently, but can be transported using the conveyor device and be actuated by the manipulator. This makes it possible to process different core bundles, which require differently designed clamping mechanisms, with just one casting installation. Alternatively, however, all clamping devices can be designed identically.

The casting installation can comprise a casting machine, a covering device being able to be formed on the casting machine, the covering device being able to cover the clamping mechanism. The covering device can be formed, for example, by one or more metal sheets which are disposed on the casting machine above the clamping mechanism. Melt or melt splashes can then not easily reach the clamping mechanism from an area of a sprue of the core bundle during a casting process. The covering device can be designed in such a manner that a gap or an opening is formed in a metal sheet between two parallel metal sheets of the covering device, the sprue being located between the gap or opening. The corresponding casting mold can then be transported to the casting machine in such a manner that the covering device does not cover the sprue during relative positioning. Optionally, the covering device can also be disposed on each of the clamping devices. In this case, each clamping device then has a covering device.

Further advantageous embodiments of a casting installation are derived from the features descriptions of the dependent claims.

In the method according to the invention for casting using a clamping device and a multi-part core bundle made of a molding material, the core bundle is subjected to a clamping force at opposite contact surfaces using at least one clamping mechanism of the clamping device, the clamping force being exerted on the core bundle using at least two clamping modules of the clamping mechanism, one clamping element of the clamping modules abutting against one of the contact surfaces of the core bundle in each instance, the clamping elements being moved independently of each other with respect to the contact surface. With regard to the advantages of the method according to the invention, reference is made to the description of the advantages of the clamping device according to the invention.

Furthermore, the method may comprise some or all of the following steps:

• • a) disposing the core bundle on a support of the clamping device.
  • b) disposing the support on a trough of the clamping device or disposing the support on a trough of the clamping device before disposing the core bundle on the support.
  • c) disposing the clamping mechanism on the support.
  • d) bracing the core bundle in the clamping device by means of the clamping module, preferably by means of a manipulator.
  • e) filling the core bundle with a casting material by means of a casting machine.
  • f) solidifying the casting material to a product and removing the clamping mechanism from the support.
  • g) demolding the cast product.
  • h) transporting and returning the clamping devices, the support and the trough using a conveyor device.

The method can be performed using a plurality of clamping devices, the clamping devices being able to be identical or different, core bundles differing geometrically being able to be braced by the clamping devices, contact surfaces of the core bundles each assigned to a clamping module being able to be designed having relative distances to the clamping module which differ to each other. If the clamping devices are identical, the identical clamping devices can also be used to brace different core bundles. The core bundles can differ in that their contact surfaces or partial surfaces of the contact surfaces are formed with relative distances to the clamping module which differ from one another. The relative distances differing between the core bundles or a difference in the relative distances can be compensated by the clamping module to such an extent that the differing core bundles can also be clamped or braced. To do this, the clamping module can move or position the clamping element with a comparatively large stroke. It is then no longer necessary to use different clamping devices for different core bundles or to use and store a number of different clamping devices for each core bundle. Nevertheless, it is also possible for the clamping devices to be designed differently, this differentiation being able to be limited to the design of the clamping mechanism. The clamping devices can then be standardized at least to the extent that they can be modularly adapted to the different core bundles. Nevertheless, the method also makes it possible to process identical core bundles using identical clamping devices.

At least one sensor can be disposed on the core bundle and/or the clamping device, a travel position of the clamping element, a clamping force of the clamping element, a temperature in or on the core bundle and/or a weight of the core bundle being able to be measured by means of the sensor. A measured value of this kind can be processed by a control device of a casting installation. By measuring the travel position of the clamping element, the clamping element can be preset to a size of the core bundle in order to accelerate the actual bracing of the core bundle. Furthermore, the clamping element can also be fed or moved towards the core bundle very quickly until the core bundle comes close to the clamping element in order to subsequently reduce the feed speed. The travel position can be easily determined using a path sensor. The clamping force can be determined using a force sensor, it then being able to also be ensured that the clamping force is sufficiently high while not leading the core bundle to break. If the core bundle breaks when a melt is poured or cooled, this breakage can be detected simply by relieving the load on the force sensor in question. A temperature sensor can easily determine a temperature at the core bundle or within the core bundle, this temperature value being able to be used to control or regulate a casting process and for a cooling phase. The weight of the core bundle can be determined using a force sensor. A control and regulation of a casting process can also be carried out in this instance, for example by determining a mold filling via the weight.

The same amount of clamping force can be exerted on all contact surfaces. For this purpose, a manipulator can be used to actuate and generate the clamping force. The manipulator can, for example, feed the corresponding clamping module until the desired clamping force is achieved. In this context, the clamping force can be distributed evenly over the contact surfaces of the core bundle. The clamping force can be achieved, for example, by means of a force sensor on the corresponding clamping module or by means of a preset torque on the manipulator.

A type of a core bundle and/or a clamping device can be detected by means of a detection mechanism of a control device of a casting installation, the core bundle and/or the clamping device being able to be marked by means of an individual marking and/or to be registered by means of a camera, parameters being able to be stored in a data bank of the control device for each type, the parameters being able to be transmitted to a manipulator for bracing the core bundle and/or a casting machine of the casting installation for each type. Core bundles or clamping devices circulating in a casting installation can all be of the same type. However, if they differ, for example if different core bundles are to be processed in the casting installation, it is essential that a type or design of the corresponding core bundle or clamping device is detected. This can be done by means of the detection device, which can then detect the type or the clamping device being processed at the individual work stations of the casting installation or with the individual work steps of the casting installation. Bracing the core bundle with a defined clamping force or casting with the casting machine with a predetermined amount of melt or casting compound is essential here. Once the type of core bundle or clamping device has been detected, the parameters required for processing, such as clamping force or quantity of melt or casting compound, can be transmitted to the manipulator or the casting machine. The type of core bundle or the clamping device can be easily determined by the fact that they are each provided with an individual marking. For example, the core bundle and/or the clamping device can be marked by means of an RFID transmitter. Furthermore, a barcode can also be applied. The barcode can also be applied to the core bundle in line with the core bundle's design, for example using a laser or similar. Alternatively or additionally, the core bundle and/or the clamping device can be recorded by means of a camera, the type then being able to be determined by image processing of the camera image. In line with the operation of the casting installation, a wide variety of core bundles can thus be processed in a random sequence.

Further advantageous embodiments of the method are derived from the descriptions of features of the dependent claims referring to a device herein.

BRIEF DESCRIPTION OF DRAWINGS

In the following, preferred embodiments of the invention are described in closer detail with reference to the enclosed drawings.

FIG. 1 shows a perspective view of a casting installation.

FIG. 2 shows a lateral view of a casting mold.

FIG. 3 shows a front view of the casting mold.

FIG. 4 shows a cross-sectional view of the casting mold.

FIG. 5 shows a longitudinal cut through the casting mold.

FIG. 6 shows a perspective partial view of a clamping device having a core bundle.

FIG. 7 shows a perspective partial view of the clamping device.

FIG. 8 shows a top view of the clamping device.

FIG. 9 shows a lateral view of the clamping device having a support.

FIG. 10 shows a lateral view of the clamping device.

FIG. 11 shows a longitudinal cut through a clamping module.

DETAILED DESCRIPTION

A combined view of FIGS. 1 to 11 shows a casting mold 10 in various views. The casting mold 10 is made of a clamping device 11 and a core bundle 12. The core bundle 12 is shown here in simplified form and is made of a plurality of cores (not shown in detail). The cores of the core bundle consist of a molding material, in particular core sand, which has been consolidated with a binder. The clamping device 11 braces the core bundle 12 in the clamping device 11, the clamping device 11 applying a clamping force to opposite contact surfaces 13 of the core bundle 12. FIG. 1 shows a casting ladle 14 of a casting machine (not shown) of a casting installation on a sprue 15 of the core bundle 12, which is braced in the clamping device 11 at this time.

The clamping device 11 is made of two clamping mechanisms 16, each with five clamping modules 17 on a clamping frame 18. The clamping modules 17 are screwed to an upper frame 19 and a lower frame 20 of the clamping frame 18. Each of the clamping modules 17 has a clamping element 21, on each of which a contact plate 22 is mounted. The contact plate 22 acts on the contact surface 13, which is divided here into a first partial surface 23 and a second partial surface 24 and is separated by a ledge 26. The flat partial surfaces 23 and 24 are disposed in offset, parallel planes 26 and 27, respectively. The clamping elements 21 or contact plates 22 can now be moved independently of one another with respect to the partial surfaces 23, 24 or the contact surface 13 by means of the clamping modules 17 so that the contact plates 22 come into contact with the contact surface 13 and apply a clamping force thereto.

As can be seen in FIG. 11, the clamping modules 17 are each designed having a spindle stock 28 having a guide 29 and a spindle 30 which can be driven by a manipulator (not shown here). The clamping element 21 is mounted for linear movement via two rods 31 in a guide body 32 of the clamping module 17. The clamping element 21 has a spring mechanism 33, which is formed by a spring bundle 34 made up of Belleville washers 35 on the corresponding rods 31. As the rods 31 are mounted in drill holes 36 with the spring bundle 34, the corresponding rod 31 is pushed a little way into the drill hole 36 when the clamping element 21 or the contact plate 22 is pressed against the contact surface 13, a clamping force being generated by means of the spring bundle 34. The contact plate 22 can simply be fed via a screw head 37 on the spindle 30 using a manipulator (not shown here), which can be a simple wrench or an electromagnetic screwdriver.

The clamping device 11 also has a support 38 and a trough 39 in which the support 38 is accommodated. The support 38 is made of a frame 40 with feet 41, a plate 42, which forms a support surface 43 for the core bundle 12, being attached to the frame 40. Furthermore, posts 44 are disposed on the frame 40 to support the core bundle 12. The posts 44 prevent the core bundle 12 from falling over during transportation or disintegration. The posts 44 are spaced apart in such a manner that the clamping elements 21 can be moved past the posts 44 to the core bundle 12. Furthermore, a through opening 45, through which the molded material of the core bundle 12 can fall downward, is formed in the plate 42. An abutment 47 for the lower frame 20 or the clamping frame 18 is formed at an upper end 46 of the feet 41. Once the core bundle 12 has been positioned on the support surface 43, the clamping frame 18 can be placed on the support 38.

The trough 39 is formed from a trough frame 48 with closed lateral surfaces 49 and 50 and a closed bottom 51. The lateral surfaces 50 are so deep that the support 38 can be inserted into or removed from the trough 39 via fork receivers 52 using, for example, an industrial truck (not shown here). In an interior 53 of the trough 39 formed in this manner, molding material can be collected and transported when the core bundle 12 disintegrates.

Above the clamping frame 18, a covering device 54 is disposed on the clamping frame 18. The covering device 54 is formed from two metal sheets 55. which cover the corresponding clamping mechanisms 16 in such a manner that no melt or melt splashes can reach the clamping mechanisms 16 directly during casting with the casting ladle 14. A gap 56. through which the sprue 15 is accessible. is thus formed between the metal sheets 55.