METHOD, CASTING MOLD AND DEVICE FOR PRODUCING A VEHICLE WHEEL

Abstract

The invention relates to a method for producing a vehicle wheel from a light-metal material, in which the light-metal material is introduced in liquid form into a mold cavity of a casting mold. The vehicle wheel is produced by means of pressurized casting, wherein the casting mold is temperature-controlled in different regions to different temperatures.

Description

The invention concerns a method for producing a vehicle wheel from a light-metal material, the light-metal material being introduced in liquid form into a mold cavity of a casting mold. Furthermore, the invention relates to a casting mold for producing a vehicle wheel from a light-metal material, having mold parts forming a mold cavity for receiving the light-metal material in liquid form, and an apparatus for producing a vehicle wheel.

The basis for driving safety and driving comfort in light-metal wheels for passenger cars are the unsprung masses, the decisive factor being that the weight of the wheels is as low as possible. Due to the mass inertia and the rotational torque, the aim is to use light-weight wheels. For this reason, on the one hand, attempts are being made to implement light-weight wheel designs. On the other hand, efforts are being made to reduce weight by selecting materials. The current state of the art is cast or forged wheels made of aluminum or magnesium alloys, a very high percentage of which are produced using the low-pressure chill casting or permanent mold casting process.

In addition to these driving dynamics requirements, aerodynamic or crash-relevant wheel designs are playing an increasingly important role. Since the aerodynamic properties of the wheels are directly related to fuel consumption and CO₂ emissions, there was also a greater need for action in the light of legislation. Due to homologation requirements within the overall approval process for passenger cars, in particular the WVTA (Whole Vehicle Type Approval) in conjunction with the WLTP (Worldwide harmonized Light vehicles Test Procedure), these requirements have become more stringent, so that the basic equipment of the complete vehicle within the approval process (WVTA) no longer describes the vehicle, but all equipment variants. This change in the type testing by the worldwide standardized light vehicle test procedure (WLTP) requires a rethinking of the design of vehicle parts in terms of aerodynamics and light-weight construction. In addition, these light-weight construction and aerodynamic requirements are underpinned by the increasing use of electric mobility in line with the motto “Light-weight construction increases range”. Depending on the vehicle type, different wheel dimensions are used, which are aerodynamically worse and cause a higher block function in frontal and offset crashes, which worsens the classification result of the entire passenger car range.

These increasing demands, consisting of light-weight construction, aerodynamics and crash, require a change in the method for the production of vehicle wheels, since standard casting processes such as low-pressure chill casting cannot optimally meet these requirements in terms of process engineering.

In the cold-chamber casting process with conventional cold-chamber casting systems for the production of cast parts, these systems build up a clamping force by generating a lock through a clamping unit consisting of three machine plates, namely a machine shield, a movable clamping plate and a fixed clamping plate, four columns along which the movable clamping plate can be moved back and forth, and a drive unit for driving the movable clamping plate, usually via a hydraulically driven toggle lever or double toggle lever. A casting mold is sampled with a movable mold half on the movable clamping plate and with a fixed mold half on the fixed clamping plate. The necessary locking force is applied via the clamping unit by clamping the columns between the machine shield and the fixed clamping plate.

In conventional cold-chamber casting systems, the fixed clamping plate is followed in the axial direction by a casting unit by means of which a melt is fed to a mold cavity formed by the casting mold perpendicular to the parting plane, i.e. perpendicular to the parting plane of the two mold halves, via a casting chamber through the fixed clamping plate and the fixed mold half of the casting mold. For this purpose, the casting unit is equipped with a normally hydraulically driven casting plunger that can be moved in the casting chamber.

An ejector unit is integrated in the clamping unit behind the movable clamping plate, which is normally also hydraulically driven to move ejector pins back and forth in the casting mold. The ejector pins are passed through the movable clamping plate to scrape the cast parts from the moving half of the casting mold after opening the casting mold. In addition, a core pulling device is usually provided, which on the machine side consists of hydraulic cylinders, for example, which are usually mounted on the moving clamping plate, sometimes also on the fixed clamping plate.

As is well known, the casting process in cold-chamber casting plants is divided into four successive phases, namely the dosing phase, the pre-filling phase, the mold-filling phase and the postpressing phase.

The dosing or metering can e.g. be carried out mechanically with a spoon or with compressed gas from a holding furnace via a channel or via a riser pipe, as in the so-called Vacural process. The dosing times are typically between 3 s and 15 s, depending on the type and quantity of dosing. If the dosing time is relatively long, there is a risk that part of the melt will already solidify in the casting chamber. Depending on the machine design, the plunger speed in the pre-filling phase can typically be adjusted in a range between 0.2 m/s and 0.6 m/s so that, on the one hand, the melt is conveyed as quickly as possible and, on the other hand, air inclusions are avoided as far as possible, e.g. by overturning of a wave of the melt building up in front of the plunger, by the formation of spray and/or by reflection in the casting residue area.

In the pre-filling phase, the casting chamber is filled with melt and the plunger conveys the melt up to the vicinity of the ingate.

To avoid cold flow points, the mold filling phase is as short as possible; its duration is usually between 5 ms and 60 ms. In the mold-filling phase, the plunger moves the melt at high speed, typically adjustable in a range of up to 10 m/s and more. At the end of the mold-filling phase, high pressures occur by converting the kinetic energy into a pressure pulse, so that there is a risk of the mold tearing. Modern casting machines therefore have means to absorb the kinetic energy towards the end of the filling phase.

In the post-pressing phase or holding-pressure phase of a cold chamber casting machine, a holding pressure of 300 bar to 1500 bar, and in some cases even more, is usually set via a multiplier. The melt solidifies under the holding pressure and air trapped during mold filling is compressed under the static holding pressure. The proportion of air trapped under the holding pressure in the volumetric porosity is low. The volumetric porosity usually consists of blowholes, the cause of which is insufficient replenishment of a shrinkage-related portion of the melt at the transition from liquid to solid.

In conventional cold-chamber casting systems, the ingates are generally thin-walled in relation to the wall thickness of the cast parts, which means that the melt is still liquid in some areas of the cast part, while it has already partially or completely solidified in the ingate area, which makes further feeding impossible or at least difficult. The formation of a solidified rim shell in the casting chamber after dosing or metering leads to the fact that part of the melt is neither available for filling the casting mold nor for feeding the shrinkage-related portion in the mold cavity. Pressing residual melt out of the casting residue area for replenishment requires a high holding pressure.

The high pressures at the end of the mold-filling phase and in the holding-pressure phase require high holding forces of the casting mold, which must be applied via the clamping unit of the casting machine.

High casting forces lead to elastic deformation of the casting mold and possibly to a bulge around the mold cavity, which can cause burr formation around the cast part in the parting plane as well as in the areas of slides and slide guides.

The high pressures require a relatively large thickness of the fixed clamping plate and consequently a correspondingly long casting chamber, which in turn limits the filling level in the casting chamber to typically 15% to a maximum of about 70%, with a correspondingly large air volume in the casting chamber. The conventional orientation of the casting unit relative to the clamping unit results in relatively long flow paths of the melt in the casting chamber and in the casting system and often a cranking of the casting system or the anvil. The application of high pressures can also lead to elastic deformation of the solidified casting residue and the casting chamber in the casting residue area and thus to jamming of the casting residue in the casting chamber, so that under certain circumstances high opening forces are required to tear the casting residue out of the casting chamber. This can lead to a high and/or premature wear of the casting chamber and the plunger. In addition, jamming of the casting residue in the casting chamber often results in the application of an excessive amount of piston lubricant, which can lead to inclusions in the cast part.

With horizontally arranged casting chambers, these are heated more in the lower area than in the upper area during filling by the hot melt, so that the thermal load causes a deformation of the casting chamber, which causes friction between the casting chamber and the casting piston, which must follow the course of the casting chamber in the pre-filling phase and the mold-filling phase. The conventional orientation of the casting chamber relative to the mold or barrel causes a vertical deflection of the melt at the transition from the casting chamber to the mold or barrel in the parting plane, which is problematic in terms of flow mechanics and also thermally problematic. Any deflection of the melt leads to turbulence during mold filling, to a higher energy requirement in the casting drive and to the risk of noticeable air inclusions and erosion in the area of the casting set and the casting mold.

The described system-related disadvantages of conventional cold chamber casting systems worsen the casting result and require a very stable and cost-intensive machine design. In addition, due to the overall design of conventional casting machines, the clamping of the casting mold is a time-consuming and cost-intensive process.

It is therefore an object of the present invention to create a method and a casting mold for producing a vehicle wheel from a light-metal material which are capable of meeting these constantly increasing requirements in terms of light-weight construction, aerodynamics and crash behavior of the vehicle wheel.

According to the invention, this object is met by the features mentioned in claim 1.

In addition to the low machine and tool requirements, the method in accordance with the invention offers the best prerequisites for meeting the above-mentioned increased requirements with the methods and systems known from the state of the art. By using pressurized casting instead of the previously used low-pressure chill casting for vehicle wheels with its limited possibilities or the conventional cold-chamber casting process for other cast parts with its current process-related disadvantages, it is possible to carry out various light-weight construction optimizations, aerodynamic optimizations and crash optimizations as well as system-related mold designs as light-weight construction and process optimization.

A method change from low-pressure chill casting with its limited possibilities with regard to casting cross-section, quality of the casting result due to high tool temperatures of over 500° C., to pressurized casting thus enables, in addition to various optimizations with regard to light-weight construction, aerodynamics and crash behavior, also system-related form designs as lightweight construction and process optimizations.

The temperature control of the casting mold according to the invention leads to a very fast and complete filling of the mold cavity, whereby segregation of the liquid light-metal material is avoided. The solution according to the invention enables a desired temperature level within the mold cavity, so that, in addition to the uneven heating of the casting mold, the associated deformation of the casting chamber is avoided and thus the premature solidification of the molten light-metal material is prevented in certain areas. In addition to increasing the service life of the pistons and the casting mold, this also reduces the piston forces.

By using pressurized casting and tempering the casting mold in different areas to different temperatures, very low forces occur during the casting process, resulting in low-turbulence or turbulence-free casting of the vehicle wheel. Although the advantages of the cold-chamber casting process are used for the production of light-metal wheels, the problems otherwise resulting from this process are avoided.

Furthermore, the method according to the invention allows very small wall thicknesses of up to 1 mm in certain areas of the vehicle wheel and in certain cases even less. The possible reduction of wall thicknesses makes it possible to design a vehicle wheel that has significantly better properties than known vehicle wheels with regard to crash behavior. In particular, the vehicle wheel produced with the method according to the invention can be optimized for a desired crash behavior.

Due to such thin wall thicknesses, the visible side of the vehicle wheel can be designed to be almost completely closed without significantly increasing the weight of the vehicle wheel. This can significantly improve the aerodynamics of the vehicle wheel. Of course, openings, for example for ventilating a vehicle brake, can also be integrated into such a visible side. A structure increasing the strength of the vehicle wheel can be located within such a disc-like design of the visible side. This means that, compared to known solutions, significant improvements can also be achieved in the aerodynamics of the vehicle wheel manufactured using the method in accordance with the invention.

A further advantage resulting from the use of the method is the low draft angle of up to 1 degree or less, which opens up previously unknown stylistic design possibilities for the vehicle wheel. Furthermore, very fine surfaces with a very small radius of 1 mm or less can be created.

The fact that the vehicle wheel can be finished in one casting reduces the machining required after casting by approximately 80% or more. The reduced post-processing requirements mean that less waste is produced, which helps to protect the environment. The method, which is in accordance with the invention, considerably reduces the casting time and enables a virtually burr-free casting, while also requiring less raw material and energy. Furthermore, the rapid casting and solidification with casting skin means that otherwise necessary artificial ageing can be completely or partially eliminated. The vehicle wheel produced with the method according to the invention has a low distortion, which also allows the fine gradations required for bright turning.

The light-weight construction achievable with the method according to the invention increases the range of motor vehicles equipped with such vehicle wheels, which contributes to a reduction of the burden on the environment.

If, in a very advantageous further development of the invention, in areas, in which the vehicle wheel has a small cross-section, the casting mold is tempered to high temperatures, and in areas, in which the vehicle wheel has a large cross-section, the casting mold is tempered to low temperatures, it is ensured that the melt remains liquid for a sufficiently long time in relatively narrow areas of the mold cavity to prevent premature solidification of the same and that in relatively wide areas of the mold cavity solidification begins in good time. Overall, this results in uniform solidification of the entire vehicle wheel to be cast.

With regard to rapid filling of the mold cavity and the associated uniform solidification of the liquid light-metal material, it has proved to be particularly advantageous if the molten light-metal material is introduced into the mold cavity at a high speed of more than 5 m/s.

It may also be provided that a venting area, in which the casting mold is vented, is tempered to a much lower temperature than the other areas of the casting mold. This ensures rapid solidification of the melt in the venting area, which prevents the melt from escaping from the casting mold. In addition, this also allows the liquid light-metal material to solidify in a compact design, despite venting, even at high casting speeds.

A casting mold for producing a vehicle wheel according to the invention is specified in claim 5.

The casting mold according to the invention enables a very simple adjustment of different temperature ranges within the casting mold through the use of the tempering devices, so that the vehicle wheel to be cast can be produced under the optimum conditions in each case. The casting mold according to the invention can have a relatively simple design and is always kept at the set temperatures by the tempering devices.

With regard to the setting of the desired temperatures at the transition of the casting mold into the mold cavity, it is particularly advantageous if the tempering devices are formed as pressurized water circuits, electric heating cartridges and/or pressurized oil circuits.

If the mold parts and/or inserts connected to the mold parts and/or venting elements consist of different materials, the heat outflow and/or heat inflow can be controlled relatively easily.

Furthermore, it may be provided that the tempering devices are in operative connection with a control device for controlling and/or regulating the temperatures of the tempered areas. In this way, the temperatures of the individual areas of the mold cavity or casting mold can be controlled or regulated very easily.

With regard to a simple construction or design of the casting mold according to the invention, an advantageous further embodiment can consist in the fact that at least two mold parts movable relative to each other are provided.

A further advantageous embodiment of the invention may consist in the fact that at least one of the mold parts has a plurality of tuning elements for adjusting the mold part to different temperatures acting on the casting mold. By means of these tuning elements at least one of the mold parts and thus the entire casting mold can be very well tuned to each other with respect to the matching of the individual components, since the tuning elements are suitable for compensating tolerances between the individual components of the casting mold. It also allows the casting mold to be used at temperatures other than those for which it was designed, thus significantly reducing costs. The tuning elements can also be made of different materials and can compensate for the different sizes of the components involved depending on the production of the molded part and the heat input of the molded part. In addition to the size compensation, the tuning elements can either insulate the heat or transfer the heat in a targeted manner, so that in addition to the molding production and the molding heat input, the different sizes are compensated and an insulating effect is achieved or heat is transferred. In addition to size compensation, the tuning elements are also capable of absorbing and/or damping the shocks and/or forces introduced.

In order to prevent the melt from escaping through the venting of the casting mold, it can also be provided that in a venting region of the mold cavity of the casting mold a surface change in the form of a tempered labyrinth-like structure and/or at least one change in cross-section and/or at least one deflection is provided.

An apparatus for producing a vehicle wheel with such a casting mold is given in claim 12.

The apparatus, which may be in the form of a casting machine, for example, can be used particularly advantageously for carrying out the method according to the invention.

In order to achieve a simple and safe opening and closing of the casting mold, it can be provided that at least one of the mold parts of the casting mold is movable in the closing direction of the casting mold relative to another mold part by means of at least one guide element not belonging to the casting mold. In this way it is also possible to avoid additional guides within the casting mold and to move the mold parts of the casting mold without such guides. By arranging the guide elements inside the apparatus and especially not inside the casting mold, the guide elements can be used for the most different casting molds, so that considerable cost savings can be achieved. In addition, in this way quick casting mold changes, i.e. quick changes of the mold parts of the casting mold, are possible.

Another advantageous embodiment of the invention may be that the mold parts are thermally separated from guide elements moving the same. This prevents excessive heating of the guide elements so that they cannot warp and a high degree of accuracy in the movement of the components of the apparatus is achieved and disturbances are avoided.

Another advantageous embodiment of the apparatus can be that at least two of the mold parts are movable by means of respective gripping elements in a direction perpendicular to the closing direction. This allows a very fast opening and closing of the casting mold, which can considerably increase the productivity of the apparatus according to the invention.

A simple and quick connection of the mold parts with the guide and/or gripping elements results when at least one of the mold parts can be connected to the at least one guide element and/or to the gripping elements by means of quick-connection means.

In order to be able to supply and/or operate the tempering devices in an effective manner, it can also be provided that respective units for supplying the tempering devices are integrated into the apparatus.

A further advantageous embodiment of the invention may be that at least one vacuum unit is provided for extracting air from the mold cavity. This vacuum unit enables the air to be sucked out of the mold cavity quickly and easily in order to fill it with the liquid light-metal material.

In the following, examples of the embodiments of the invention are shown in principle on the basis of the drawings.

In the drawings:

FIG. 1 is a side view of an apparatus according to the invention in a first state;

FIG. 2 is a view according to arrow II of FIG. 1;

FIG. 3 is a perspective view of the apparatus of FIG. 1;

FIG. 4 is a side view of the apparatus of FIG. 1 in a second state;

FIG. 5 is a perspective view of the apparatus of FIG. 4;

FIG. 6 is a side view of the apparatus of FIG. 1 in a third state;

FIG. 7 is a perspective view of the apparatus of FIG. 6;

FIG. 8 is a side view of the apparatus of FIG. 1 in a fourth state;

FIG. 9 is a perspective view of the apparatus of FIG. 8;

FIG. 10 is a casting mold according to the invention;

FIG. 11 is a further view of a part of the casting mold according to the invention; and

FIG. 12 is another view of a part of the casting mold according to the invention.

FIGS. 1 to 9 show different views of an apparatus 1 for producing a vehicle wheel 2 shown in FIGS. 6 to 9 by means of pressurized casting. The vehicle wheel 2 can basically be of any size and shape. The vehicle wheel 2 shown in FIGS. 6 to 9 is therefore to be regarded as purely exemplary. A light-metal material is used for the pressurized casting of the vehicle wheel 2, preferably an aluminum or magnesium material. For this purpose, light-metal materials known per se and suitable for the method described below can be used for the production of the vehicle wheel 2.

The apparatus 1 has a casting mold 3, which in the representation of FIGS. 1, 2 and 3 is in a closed position. In the present case, the casting mold 3 has four mold parts, namely a rigid or immobile mold half 4, a movable mold half 5, an upper gate or slide 6 and a lower gate or slide 7. The mold parts of the casting mold 3 can be accommodated with or without a zero point system and they can have a very smooth and high-quality surface which does not need to be treated with a coating or the like, or only to a very limited extent, resulting in a very high surface quality of the vehicle wheel 2. Of course, the casting mold 3 can also have more than the four mold parts described and illustrated here. The movable mold parts, i.e. the movable mold half 5, the upper slide 6 and the lower slide 7, can be brought from the state shown in FIGS. 1, 2 and 3 to the states according to FIGS. 4 and 5, 6 and 7 as well as 8 and 9 by means of the respective guide elements described below. All of these guide elements described below are part of the apparatus 1 and do not belong to the casting mold 3.

For guiding the movement of the movable mold half 5 in the closing direction of the casting mold 3, marked with the arrow “x” in FIG. 1, and against this closing direction x, several horizontally running guide columns 8 are used, which are mounted on one side on a movable clamping plate 9 and on the other side on a rear machine shield 10, which forms a counter bearing. By moving the movable clamping plate 9, which is also a guide element for the casting mold 3, against the closing direction x, the movable mold half 5 is brought from its position shown in FIG. 1 to the position shown in FIG. 4. When the movable mold half 5 is moved relative to the rigid mold half 4, the upper slide 6 and the lower slide 7 are also moved against the closing direction x relative to the rigid mold half 4. Drive devices known per se and not shown herein can be used to drive the movable clamping plate 9, which in this case is movably mounted on rails 11 of apparatus 1. The guide columns 8 form a guide for the movable clamping plate 9 and absorb the horizontal clamping forces during casting. The rigid mold half 4 is attached to a fixed clamping plate 12 which is connected to a casting unit 13 which serves to introduce the liquid light-metal material into a mold cavity 14 formed between the mold parts of the casting mold 3, which in a manner known per se comprises the negative mold of the vehicle wheel 2 to be produced. The filling of the mold cavity 14 with the liquid light-metal material takes place in particular from the outer circumference of the mold cavity 14. The casting mold 3 is preferably designed in such a way that spraying of the material is avoided when the liquid light-metal material is introduced into the mold cavity 14. The liquid light-metal material is introduced into the mold cavity 14 at a relatively low pressure of up to 100 bar or slightly more.

During the actual casting process, the movable clamping plate 9 and the fixed clamping plate 12, on which the movable clamping plate 9 is supported, also generate the clamping force. For this purpose, the drive elements or devices used to move the movable clamping plate 9 can have hydraulic cylinders and/or toggle lever elements or mold closing elements, for example. The casting mold 3 can be clamped by means of manual, semi-automatic or fully automatic clamping elements via form fit and/or frictional connection. The fixed clamping plate 12 can have a mold spraying device not shown and/or an integrated pressure medium system.

The upper slide 6 can be moved from its position shown in FIG. 1 or FIG. 4 to the position shown in FIG. 6, in which the upper slide 6 has been moved vertically upwards relative to the movable mold half 5, by means of an upper gripping element 15. In a similar way the lower slide 7 can also be moved downwards by means of a lower gripping element 16 from its position shown in FIGS. 1 and 4 to its position shown in FIG. 6 relative to the movable mold half 5. The gripping elements 15 and 16 as well as the movable clamping plate 9 can be operated manually, semi-automatically or fully automatically. The two gripping elements 15 and 16 also represent guide elements for the casting mold 3. The guide elements for moving the mold parts of the casting mold 3 can also be equipped with a pressure medium in a way not shown.

While in the present case the upper slide 6 and the lower slide 7 are moved in the vertical direction, it would also be possible to separate the casting mold 3 in the area of the two slides 6 and 7 in the vertical direction and thus move the two slides in the horizontal direction. The two gripping elements 15 and 16 would be left and right gripping elements in this case. Preferably, the two slides 6 and 7 are moved by means of the respective gripping elements 15 and 16 in a direction perpendicular to the closing direction x.

In the method for the production of the vehicle wheel 2 carried out with the apparatus 1 and the casting mold 3, the light-metal material is thus introduced in liquid form into the mold cavity 14 of the casting mold 3 by means of the casting unit 13. This introduction of the liquid light-metal material takes place at a high speed of more than 5 m/s. This high speed is achieved by a corresponding movement of a piston of the casting unit 13 not shown. The vehicle wheel 2 is produced by means of pressurized casting, whereby the casting mold 3 is tempered to different temperatures in different areas. This different tempering of casting mold 3 will be described in more detail at a later date using an example. Preferably, in areas in which the vehicle wheel 2 has a small cross-section, the casting mold 3 is tempered to high temperatures and in areas, in which the vehicle wheel 2 has a large cross-section, the casting mold 3 is tempered to low temperatures. The temperature control of the casting mold 3 allows the solidification behavior of the liquid light-metal material to be controlled or adjusted, although the vehicle wheel 2 has very different cross-sections. In addition, an area, in which the casting mold 3 is vented, is tempered to a much lower temperature than the other areas of the casting mold 3. This area, in which the casting mold 3 is vented, will also be described in more detail later.

The mold parts of the casting mold 3, i.e. the rigid mold half 4, the movable mold half 5, the upper slide 6 and the lower slide 7, can consist entirely or partially of different materials. In particular, the materials of the individual mold parts can be selected depending on the temperatures to be set when the casting mold 3 is tempered.

After the liquid light-metal material has solidified, the mold parts are moved apart in the manner described above to open the casting mold 3. Ejection of the cast part produced by the method, i.e. the vehicle wheel 2, is carried out by means of an ejector unit 17 which, like the guide columns 8, is mounted on the one hand on the movable clamping plate 9 and on the other hand on the rear machine shield 10. In the present case, the ejector unit 17 has a hydraulic unit 18, which ensures the movement of the ejector unit 17 in a manner known per se. After ejection of the vehicle wheel 2 from the casting mold 3, the casting mold 3 can, in the opposite direction, i.e. from the state according to FIGS. 8 and 9 over the state according to FIGS. 6 and 7, the state according to FIGS. 4 and 5 be brought to the state according to FIGS. 1, 2 and 3, in order to produce the next vehicle wheel 2 by introducing the liquid light-metal material into the mold cavity 14.

After completion, the represented vehicle wheel 2 can of course be connected to a tire not shown in the drawings to be filled with air or gas. The vehicle wheel 2 can also consist of several individual parts, which can also be produced using the method described herein.

FIGS. 10, 11 and 12 show an exemplary embodiment of the casting mold 3, showing the rigid mold half 4, the movable mold half 5, the upper slide 6 and the lower slide 7. The upper gripping element 15 and the lower gripping element 16 can also be seen in these figures. FIG. 10 also shows that the upper slide 6 and the lower slide 7 are connected to the upper gripping element 15 and the lower gripping element 16 respectively by means of quick-connection means 19 and 20, by means of which it is possible to quickly connect the guide elements belonging to the apparatus 1 with the mold parts belonging to the casting mold 3 in order to ensure quick opening and closing of the casting mold 3 by moving the mold parts relative to each other as described above.

In addition, FIG. 10 shows that the upper slide 6, the lower slide 7 and the movable mold half 5 are thermally separated from the corresponding guide elements, i.e. the upper gripping element 15, the lower gripping element 16 and the movable clamping plate 9. Corresponding insulating elements 21 are provided for this purpose, not all of which are visible due to the course of the sectional view and which may also be provided between the rigid mold half 4 and the fixed clamping plate 12. This thermal separation of the mold parts from the guide elements prevents unintentional heating of the guide elements, so that the function of the apparatus 1 with regard to the opening and closing of the casting mold 3 is guaranteed even in the event of temperature changes.

FIG. 10 also shows several tempering devices by means of which the casting mold 3 can be tempered to different temperatures in order to enable uniform solidification of the light-metal material within the mold cavity 14. The tempering devices are preferably pressurized water circuits, of which several holes 22 are shown in FIG. 10, electric heating cartridges 23 and pressurized oil circuits, of which several holes 24 are also shown in FIG. 10. If necessary, other heating or cooling elements can also be used as tempering devices.

The tempering devices, i.e. the pressurized water circuits, the electric cartridge heaters 23 and/or the pressurized oil circuits are connected to a control device 25, also shown in FIG. 10, so that the temperatures of the areas temperature controlled by the tempering devices can be controlled and/or regulated. The control device 25 can also be in operative connection with temperature sensors not shown, which measure the actual temperature of the individual parts of the casting mold 3 and thus enable the temperature to be set correctly. The control device 25 is also capable of monitoring the temperatures of the molded part or of the molding zones in addition to other process data and/or geographical data and/or other monitoring information and transmitting them to a higher-level system, for example a machine control system. In this way, the casting mold 3 can be specifically tempered during production and/or for preheating, whereby all influencing parameters, such as different thermal expansions of the components involved, can be monitored and controlled based on the different temperatures and thermal expansion coefficients of the mold parts.

The temperature control of the casting mold 3 can of course be designed differently for each individual mold and thus for each individual vehicle wheel 2 to be produced with the casting mold 3 or the apparatus 1.

FIGS. 1, 4, 6 and 8 show very schematically units 26, which are used to supply the temperature control units for the temperature control of the casting mold 3 and which are integrated in the apparatus 1. In the present case, the units 26 are shown as being integrated in the rails 11. However, the units 26 can of course also be located or attached at other positions within the apparatus 1.

Furthermore, FIGS. 1, 4, 6 and 8 show a vacuum unit 27, which is used to extract air from mold cavity 14. The vacuum unit 27, by means of which a corresponding vacuum is generated, is also integrated in the apparatus 1 and again shown purely as an example in the rails 11. The connection of the units 26 with the tempering devices and the connection of the vacuum unit 27 with the mold cavity 14 are not shown in the figures; they can be carried out in the most varied and familiar ways.

FIG. 11 shows a perspective view of a part of the casting mold 3, in which the upper slide 6, the lower slide 7, the movable mold half 5, the control device 25 and a part of the mold cavity 14 can be seen. The two gripping elements 15 and 16 as well as their connection to the two slides 6 and 7 can also be clearly seen in FIG. 11. Furthermore, it results from FIG. 11 that at least one of the moldings, in the present case both the upper slide 6 and the lower slide 7, has several tuning elements 28 by means of which the moldings can be matched or tuned to each other. In the present case, the two slides 6 and 7 are matched to the rigid mold half 4 not shown in FIG. 11 by means of the tuning elements 28. In this way, tolerance deviations that inevitably occur during the manufacture of the individual mold parts can be compensated. Furthermore, the tuning elements 28 serve to adjust the mold parts of the casting mold 3 to different temperatures acting on the casting mold 3. The tuning elements 28, which can also be denominated as insert parts, can be made of a different material than the slides 6 or 7 in or on which they are arranged.

By means of the tuning elements 28, which have the most varied thicknesses and can also be designed as tuning cylinders if necessary, it is possible to tune the casting mold 3 in separating areas between the mold parts of the casting mold 3 in such a way that all mold parts of the mold remain closed even under bursting pressure in order to prevent the liquid light-metal material from escaping. In this way, the mold parts of the casting mold 3 with their temperature zones can be adjusted in such a way that, in addition to the technological and economic requirements that inevitably arise with vehicle wheels 2, the technological and economic design of the casting mold 3 in conjunction with the problems that arise with conventional molds is also taken into account in the production of vehicle wheels 2. The tuning elements 28 can also be reworked or exchanged after appropriate testing, so that a secure sealing of the casting mold 3 is guaranteed.

FIG. 12 shows a view of another mold part of the casting mold 3, namely the rigid mold half 4, which has a venting area 29 adjoining the mold cavity 14, through which the air inside the mold cavity 14 at the start of the casting process can escape. To prevent the liquid light-metal material from escaping from the venting area 29 in addition to the air, the venting area is, as already mentioned, tempered to a much lower temperature than the other areas of the casting mold 3. In addition, a temperature-controlled or tempered, labyrinth-like structure 30 is provided in the venting area 29, which makes it more difficult for the liquid light-metal material to escape from the mold cavity 14. In addition or as an alternative to the labyrinth-like structure 30, the venting area 29 may also have cross-sectional changes, surface enlargements or surface reductions and/or deflections. The venting area 29 or a venting element forming the venting area 29 can be made of a different material than the other components of the casting mold 3. For example, copper materials such as brass or bronze can be used for the venting area 29. Of course, the same or similar venting areas as the venting area 29 can also be located at other points in the mold cavity 14.

The venting area 29, which can also be denominated as a venting unit, enables a system that brakes the liquid light-metal material in itself through its own heat management in conjunction with the geometric design described, so that, depending on the requirements, a connection to the vacuum unit 27 can be controlled selectively with full cross-section or reduced cross-section via one or more holes 31 in order to be able to realize short venting distances. In some cases, these venting areas 29 can also be provided with a vacuum valve connection or can also be used without a subsequent vacuum connection in order to serve as a complete or partial overflow for the casting mold 3.

FIG. 12 also shows a closed belt or ring 32, which is formed by offsetting the planes of the rigid mold half 4. In the closed state of the casting mold 3 the tuning elements 28 rest against the ring 32 in order to guarantee the tightness of the casting mold 3. The ring 32 thus absorbs the forces occurring during casting.

Claims

1. A method of producing a vehicle wheel from a light-metal material comprising introducing a light-metal material in liquid form into a mold cavity of a casting mold, wherein the vehicle wheel is produced using pressurized casting, and wherein the casting mold is tempered to different temperatures in different areas.

2. The method of claim 1, wherein in areas in which the vehicle wheel (2) has a small cross-section, the casting mold is tempered to high temperatures, and in areas in which the vehicle wheel has a large cross-section, the casting mold is tempered to low temperatures.

3. The method of claim 1, wherein the molten light-metal material is in a molten state and is introduced into the mold cavity at a speed of more than 5 m/s.

4. The method of claim 1, wherein a venting area, in which the casting mold is vented, is tempered to a much lower temperature than the other areas of the casting mold.

5. A casting mold for producing a vehicle wheel from a light-metal material comprising mold parts that form a mold cavity for receiving the light-metal material in liquid form, wherein the casting mold has areas tempered to different temperatures using tempering devices.

6. The casting mold of claim 5, wherein the tempering devices are formed as pressurized water circuits, electric heating cartridges, and/or pressurized oil circuits.

7. The casting mold of claim 5, wherein the mold parts and/or inserts connected to the mold parts and/or venting elements comprise different materials.

8. The casting mold of claim 5, wherein the tempering devices are in operative connection with a control device for controlling and/or regulating the temperatures of the tempered areas.

9. The casting mold of claim 5, wherein at least two mold parts movable relative to each other are provided.

10. The casting mold of claim 5, wherein at least one of the mold parts has a plurality of tuning elements for adjusting the mold part to different temperatures acting on the casting mold.

11. The casting mold of claim 5, wherein in a venting area of the mold cavity of the casting mold a surface change in the form of a tempered labyrinth-like structure and/or at least one change in cross-section and/or at least one deflection is provided.

12. An apparatus for producing a vehicle wheel comprising the casting mold of claim 5.

13. The apparatus of claim 12, wherein at least one of the mold parts of the casting mold is movable in the closing direction of the casting mold relative to another mold part by means of at least one guide element not belonging to the casting mold.

14. The apparatus of claim 12, wherein the mold parts are thermally separated from guide elements moving the same.

15. The apparatus of claim 12, wherein at least two of the mold parts are movable by means of respective gripping elements in a direction perpendicular to the closing direction.

16. The apparatus of claim 13, wherein at least one of the mold parts can be connected to the at least one guide element and/or to the gripping elements by means of quick-connection means.

17. The apparatus of claim 12, wherein respective units for supplying the tempering devices are integrated into the apparatus.

18. The apparatus of claim 12, wherein at least one vacuum unit is provided for extracting air from the mold cavity.