CASTING MOLD FOR THE PRODUCTION OF A CASTING HAVING A FRONT AND A BACK FROM A HARDENABLE CASTING COMPOUND

Abstract

A casting mold for producing a casting having a front side and a rear side from a curable casting compound, including at least a first mold part shaping the front side and a second mold part shaping the rear side, the mold parts together delimiting a casting cavity. The first mold part has a first metal layer delimiting the casting cavity and the second mold part has a second metal layer delimiting the casting cavity. At least one metal layer is at least partially deformable for the purpose of changing the casting cavity volume. At least one mold part has an areal intermediate layer which is composed of an elastically deformable and compressible material and against which the metal layer of the mold part is movable with build-up of a restoring force on the part of the deforming intermediate layer.

Claims

1. A casting mold for producing a casting having a front side and a rear side from a curable casting compound, comprising at least a first mold part shaping the front side and a second mold part shaping the rear side, said mold parts together delimiting a casting cavity, wherein the first mold part has a first metal layer delimiting the casting cavity and the second mold part has a second metal layer delimiting the casting cavity, wherein at least one metal layer is at least partially deformable for the purpose of changing the casting cavity volume, wherein at least one mold part has an areal intermediate layer which is composed of an elastically deformable and compressible material and against which the metal layer of the mold part is movable with build-up of a restoring force on the part of the deforming intermediate layer.

2. The casting mold according to claim 1, wherein the second mold part has the intermediate layer and the second metal layer is movable against the intermediate layer.

3. The casting mold according to claim 1, wherein the intermediate layer is composed of an elastic and compressible plastics material.

4. The casting mold according to claim 2, wherein the intermediate layer is composed of foam rubber.

5. The casting mold according to claim 3, wherein the intermediate layer has a Shore A hardness of 5°-35°, preferably 15°+/−5°.

6. The casting mold according to claim 1, wherein the intermediate layer has a thickness of 2-10 mm, in particular of 3-7 mm and preferably of 4-6 mm.

7. The casting mold according to claim 1, wherein the intermediate layer covers at least 50% of the surface, preferably the entire surface, with which the metal layer delimits the casting cavity.

8. The casting mold according to claim 1, wherein a heating device which covers the rear side of the movable metal layer in an areal manner and which bears against the areal intermediate layer is provided on said rear side.

9. The casting mold according to claim 7, wherein the heating device has tubular or band-like heating elements which are embedded in an elastic compound.

10. The casting mold according to claim 8, wherein the compound is a thermally conductive compound.

11. The casting mold according to claim 1, wherein the intermediate layer is arranged directly on a mold part carrier of the mold part.

12. The casting mold according to claim 1, wherein the first mold part has a first mold part carrier and the second mold part has a second mold part carrier, wherein the first and the second mold part carrier is composed of polymer concrete.

13. The casting mold according to claim 1, wherein the first and the second metal layer are composed of nickel.

14. The casting mold according to claim 1, wherein the first metal layer has a thickness of 3-8 mm, in particular of 4-7 mm and preferably of 6 mm, and the second metal layer has a thickness of 1-4 mm and preferably of 2.5 mm.

15. The casting mold according to claim 1, wherein a heating device which covers the rear side of the non-movable metal layer in an areal manner is provided on said rear side.

16. The casting mold according to claim 15, wherein the heating device has tubular or band-like heating elements which are embedded in an elastic compound.

17. The casting mold according to claim 16, wherein the compound is a thermally conductive compound.

18. The casting mold according to claim 1, wherein an insulation element is arranged on the metal layer of the first or of the second mold part in a peripherally encircling manner, said insulation element in the closed position bearing peripherally against the other metal layer and thermally separating the two metal layers, which do not come into contact with one another, from one another.

19. The casting mold according to claim 1, wherein the insulation element consists of a plastic, in particular of a thermoplastic, a thermoset or an elastomer.

20. The casting mold according to claim 18, wherein the peripheral region of the metal layer against which the insulation element is placed during the closing operation is of stepped embodiment, and has a first bearing region against which the insulation element first runs and a second bearing region against which the insulation element, pinched between the first bearing region and the metal layer bearing the insulation element, runs after the deformation thereof.

21. The casting mold according to claim 1, wherein an encircling sealing element which bears against the insulation element in the closed position is provided on the metal layer against which the insulation element runs during the closing operation, wherein preferably the sealing element is received in a groove between the first and the second abutment region.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0034] FIG. 1 shows a diagrammatic illustration of a casting mold according to the invention,

[0035] FIG. 2 shows an enlarged partial view of region II from FIG. 1, and

[0036] FIG. 3 shows an enlarged partial view of region Ill from FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1 shows a diagrammatic illustration of a casting mold 1 according to the invention which is used to produce a casting, having a front side and a rear side, in the form of a kitchen sink consisting of a composite material. The casting mold comprises a first mold part 2 which is used to shape or define the front side of the casting to be produced, and a second mold part 3 which is used to shape or define the rear side of the casting to be produced. Both mold parts lie peripherally against one another and delimit a casting cavity 4 into which a casting compound 5 consisting of a curable polymer compound, that is to say a reaction compound, into which particulate fillers such as quartz sand and the like are introduced, is introduced. While the first mold part 2 is regularly positionally fixed, the second mold part 3 can be moved vertically, that is to say can be placed onto the lower first mold part 2 for the purpose of closing the casting cavity 4.

[0038] The casting cavity 4 itself is delimited by a first metal layer 5, which is arranged on the first mold part 2, and a second metal layer 6, which is arranged on the second mold part 3. The introduced casting compound comes into contact with these two metal layers 5, 6, that is to say bears against these two metal layers 5, 6 in an areal manner. In this case, a first heating device 7, which covers the rear side of the first metal layer in a virtually full-area manner, is arranged on the rear side of the first metal layer 6. This heating device can be used to control the temperature of the first metal layer 5, and said first metal layer can be used to heat the casting compound from the front side. The second mold part 3 also has a second heating device 8 which is arranged on the rear side of the second metal layer 6, so as to ultimately cover it in a full-area manner. The second heating device 8 can be used to control the temperature of the second metal layer 6, and said second metal layer can be used to control the temperature of the casting compound, consequently it is thus possible to control the heat input into the casting compound from the rear side. The second heating device 8 is followed by an elastic and compressible intermediate layer 9, preferably composed of a foam rubber, which elastic, compressible intermediate layer constitutes a restoring means or restoring element which makes a certain degree of movability of the second metal layer 6 possible and which at the same time ensures that the second metal layer 6 can be returned back into a defined starting position. The function of the elastic and compressible intermediate layer 9 is discussed in even greater detail below with reference to FIG. 2.

[0039] Furthermore, the first mold part 2 has a first mold part carrier 10 against which, in turn, the first heating device 7 bears. The second mold part 3 also has a second mold part carrier 11 against which the elastic intermediate layer 9 bears. Both mold part carriers 10, 11 are preferably at least partially composed, insofar as the metal layers are supported thereon, of a polymer concrete.

[0040] FIG. 2 shows an enlarged view of region II from FIG. 1, illustrating the mutually opposite regions of the first mold part 2 and of the second mold part 3 with formation of the casting cavity 4. Shown on the right is the first mold part 2 with its mold part carrier 10 composed of the polymer concrete, consisting of a polymer matrix 13 comprising fillers embedded therein, for example gravel or sand particles and the like. The mold part carrier 10 is followed by the first heating device 7, consisting of tubular heating elements 17 which are guided, for example, in a meandering form or as heating coils and the like and which are embedded in a thermally conductive compound 18. In this case, a temperature-controlled heating fluid such as water flows through the heating elements 17. As an alternative thereto, electrical heating bands or the like may also be provided as heating elements 17.

[0041] Arranged on the heating device 7, in direct contact therewith, is the first metal layer 5 which is a nickel sheet for example having a thickness of 6 mm. As is apparent, this first metal layer 5 directly delimits the casting cavity 4.

[0042] Also shown is a detail of the second mold part 3 with its mold part carrier 11, likewise consisting of a polymer matrix 15 comprising fillers 16 embedded therein, again in the form of gravel or sand particles, etc. This mold part carrier 11 is followed by the elastic and compressible intermediate layer 9 which is formed from a foam rubber 35, that is to say from an elastic, foamed plastics material. A foam rubber 35 is a largely closed-pore, elastic and compressible foam, that is to say a sponge rubber, which consists of a foamed rubber material. This elastic intermediate layer 9 has a thickness preferably of about 4 mm, and a Shore A hardness of 5°-35°, preferably of 15°+/−5°. The second heating device 8 is connected to the mold part carrier 11 by way of this elastic and compressible intermediate layer 9, wherein here the second heating device 8 also consists of a thermally conductive compound 19 comprising heating elements 20 in the form of heating tubes which are embedded therein and which, like the tubular heating elements 17, are for example copper tubes and are likewise flowed through by a heating fluid. It is true of at least the thermally conductive compound 19, and possibly of both thermally conductive compounds 18, 19, that they are elastic, that is to say flexible, such that the areal or mat-like heating devices 7, 8 can be laid so as to follow the three-dimensional shape of the respective mold part carrier 10, 11 without any problems, and can, on the part of the second heating device 8, in particular participate in the movement of the elastic intermediate layer.

[0043] Lastly, the second metal layer 6 is arranged on the heating device 8, said second metal layer likewise being a nickel sheet but which only has a thickness of about 2.5 mm, which is necessary since this second metal layer 6 is movable, that is to say the position thereof changes during the actual production. This is made possible by virtue of the fact that the second metal layer 6, together with the second heating device 8, can be moved, that is to say the position thereof can change, relative to the second mold part carrier 11 by way of the elastic intermediate layer 9.

[0044] If a casting operation is commenced, the second metal layer 6 is in its starting position, and the casting cavity 4 has a defined starting volume. The second metal layer 6 is at a defined spacing to the first metal layer 5, and the intermediate layer 9 is relaxed and only compressed to a slight extent, if at all. At the beginning of the casting operation, the casting compound, which may be a sufficiently flowable compound based on polyacrylate or polymethacrylate, is introduced into the casting cavity 4 at pressure. The casting pressure lies in the range of about 2-5 bar. As a result of this notably high pressure within the casting cavity 4, which is necessary in order to ensure that the casting compound is distributed throughout the casting cavity 4, a correspondingly high surface pressure builds up in the direction of the two metal layers 5, 6. The position of the first metal layer 5 does not change, since it is supported directly on the first mold part carrier 10. By contrast, the second metal layer 6 evades the pressure which is building up. As a consequence of the pressure, the elastic intermediate layer 9 is compressed here, that is to say it is compressed over the entire surface thereof, which is possible since it is supported, in turn, on the positionally fixed second mold part carrier 11. This means that the casting cavity volume can be increased due to the high injection pressure, resulting from a movement of the second metal layer 6 against the elastic and compressible intermediate layer 9 or the foam rubber 35, which is compressed here with build-up of a restoring force.

[0045] The polymerization process is then initiated, which is regularly effected by actuating the first heating device 7, thus consequently a heating fluid circulates through the heating elements 17. Homogeneous heating of the heating device 7 and, by way of the latter, of the first metal layer 5 occurs here. Said first metal layer then, in turn, heats the casting compound in the casting cavity 4, said casting compound increasing in volume to some extent as a consequence of the temperature, which leads to further compression of the elastic intermediate layer 9 since the internal pressure in the casting cavity 4 is increased further by this increase in volume of the casting compound.

[0046] If the local heating at the interface to the first metal layer 5 is so great that a polymerization start temperature is reached, the exothermic polymerization reaction begins at this interface, that is to say that the polymer matrix is polymerized to completion, wherein this polymerization front gradually migrates into the casting compound, that is to say moves in the direction of the second metal layer 6. In this case, the temperature of the second metal layer 6 is also controlled in due course by way of the second heating device 8, in order to consequently also control the polymerization reaction from this side. This means that the polymerization reaction is also initiated from this side, in accordance with a defined time schedule. Since, as described, the polymerization reaction is exothermic, it progresses automatically within the volume.

[0047] However, the polymerization is also accompanied by shrinkage of the casting compound or of the polymerized casting being produced, thus consequently by a reduction in volume. In order to nevertheless ensure that the casting compound or the completely polymerized outer skin of the casting is always in contact both with the first metal layer 5 and with the second metal layer 6, the second metal layer 6, which has previously moved out of its starting position with compression of the elastic intermediate layer 9, is then automatically restored, that is to say tracks the polymerization shrinkage, by way of the elastic, compressed intermediate layer 9, which relaxes or increases in size. The intermediate layer 9 has, as described, built up a restoring force during the compression. If the internal pressure in the casting cavity 4 then decreases as a result of the compound shrinkage, the compressed elastic intermediate layer 9 can relax again, that is to say the volume thereof increases again and continuously pushes the second metal layer 6 back in the direction of its starting position, such that continuous contact between the second metal layer 6 and the casting compound or the casting is accordingly provided.

[0048] Due to the integration of the elastic and compressible intermediate layer 9, the second mold part 3 is accordingly of automatically adjusting or self-adjusting embodiment, without any additional external elements being necessary for the required movement of the second metal layer 6. Rather, an automatic restoring device is provided by way of the integrated elastic and compressible intermediate layer 9, that is to say the foam rubber layer, the operation of said restoring device requiring no actuating means or other elements. Rather, inherent control is effected exclusively by way of the internal pressure in the casting cavity 4 and thus ultimately by way of the casting compound or the polymerization operation thereof itself.

[0049] The heating or operation of the two heating devices 7, 8 is correspondingly controlled in the course of the production method. The polymerization is, as described, started from the visible side, that is to say from the first mold part 2, and thus by way of the first heating device 7. In this case, the tubular heating elements 17 are either laid, or divided into groups that are correspondingly separately heatable, in such a way that heating is initially effected at the encircling outer periphery of the mold cavity 4 so that the polymerization reaction first starts there, since the second metal layer 6 is movable only to a negligible extent, if at all, directly at the periphery, for which reason polymer shrinkage cannot be compensated there, as is however the case within the volume. However, since the casting compound within the volume is still fluid while the polymerization has already started at the periphery, the shrinkage compensation can be effected by way of the casting compound volume. This means that locally different temperature control is ultimately possible by way of the first heating device 7.

[0050] The heating by way of the second heating device 8, that is to say from the second mold half, may be effected with a time delay, for example only after several minutes, example after about five minutes, that is to say when the polymerization has already started at the periphery and possibly also on the side of the first metal layer 5. This accordingly means that both a local heating profile and a temporal heating profile may be operated individually, ultimately in dependence on the reaction kinetics.

[0051] FIG. 3 shows an enlarged partial view of region III from FIG. 1. This region shows the region in which the lower mold part 2 shaping the front side abuts against the upper mold part 3 shaping the rear side. Shown in a detail are the respective mold part carrier 10, 11, the respective heating device 7, 8 and the two metal layers 5, 6, which lie one above the other in each case in the peripheral region shown in FIG. 2. The casting cavity 4 extends into this region of overlap, in which the two metal layers 5, 6 thus overlap one another as seen vertically.

[0052] However, here, unlike in the prior art, the two metal layers 5, 6 do not bear against one another with direct contact. Instead, the two metal layers 5, 6 are thermally decoupled from one another. This is realized by virtue of the fact that an insulation element 21 is arranged on the second metal layer 6, said insulation element being embodied as a strip and consisting of a plastics material, especially a thermoplastic, a thermoset or an elastomer, and in particular of POM or a polyurethane elastomer. In the example, a stepped abutment surface 22, which bears the strip-like, cross-sectionally rectangular insulation element and to which the insulation element 21 is for example adhesively bonded, is formed on the metal layer 6. The insulation element 21 runs around the entire periphery, and it may consist of a plurality of element portions adjoining one another. For reception thereof, the abutment surface 22 is of stepped embodiment, such that an abutment edge 23 is formed, against which the insulation element 21 bears in the direction of the casting cavity 4.

[0053] The first mold part 2 also has an abutment surface 24 of stepped embodiment on the first metal layer 5. On the one hand, a first bearing region 25 is realized which forms a first raised region on which the insulation element 21 rests. A second bearing region 28 follows, separated by way of an encircling groove 26 in which a sealing element 27 in the form of a sealing cord or a sealing rubber or the like is received, said second bearing region, like the first receiving region 25, being of areal form but being slightly lower than the first receiving region 25. Accordingly, a defined height profile is formed on the bearing surface 24. The height difference between the first and second bearing region 25, 28 is for example 1 mm.

[0054] As shown in FIG. 3, in the further periphery profile, the second metal layer 6 is of angled embodiment and is supported on a support 29 of the second mold part carrier 11 by way of an insulating layer 30 and is clamped thereon by way of a clamping strip 31. In the example shown, a further clamping strip 32 is fastened to this clamping strip 31 and is used to peripherally clamp the insulation element 21, possibly also in addition to the adhesive bonding.

[0055] Correspondingly, in the further peripheral region, the first metal layer 5 is also of angled embodiment and is supported on a support 33 of the first mold part carrier 10 by way of an insulation 34.

[0056] If the casting mold 1 is closed, the upper second mold part 3 is moved vertically downward in the direction of the lower first mold part 2. Contact between the two mold parts 2, 3 occurs uniquely and solely in the peripheral region, and here also exclusively between the encircling insulation element 21 and the lower metal layer 5. As described, the insulation element 21 projects from the bearing surface 22 in the direction of the bearing surface 24 of the first metal layer 5. As the degree of lowering increases, the insulation element 21 first runs against the first bearing region 25 and at the same time also against the sealing element 27. As the lowering continues and the load acting on the insulation element 21 increases, the insulation element 21 is deformed to some extent, since it consists, as described, of a plastics material which has a certain degree of softness or elasticity. On account of the deformation, it then comes into abutment against the second bearing region 28. This means that it is supported in encircling fashion over a large area by way of the two bearing regions 25, 28, such that a large support surface is produced, which leads to a low surface pressure. The compressed sealing element 27 forms a further sealing plane in addition to the sealing of the casting cavity 4 by way of the insulation element 21 itself.

[0057] As shown in FIG. 3, in the closed position, there is accordingly no contact at any point between the two metal layers 5, 6. The two mold parts 2, 3 are connected to one another and, respectively, supported and sealed in relation to one another solely by way of the insulation element 21. In this case, the insulation element 21 also projects into the casting cavity 4 to a slight extent or delimits the latter, such that a corresponding spacing between the two metal layers 5, 6 is also provided virtually horizontally.

[0058] What is achieved by the thermal decoupling is that there is no heat transfer whatsoever between the two metal layers 5, 6 or no temperature compensation takes place, rather both metal layers are heatable individually and separately by way of the assigned heating devices 7, 8. This makes it possible for individual temperature profiles to be operated on the front side and rear side, as are required for the polymerization operation and the control thereof.

[0059] However, the insulation element 21 is used not only for thermal insulation but also for compensation of any unevennesses in the bearing surfaces or bearing regions. This is because, as described, the insulation element is elastic or flexible enough to be able to be adapted precisely to the respective shape of the bearing region, in particular of the first bearing region 25 in the direction of the casting cavity 4. Since the insulation element 21 is also pinched, a completely gap-free abutment is accordingly provided, meaning that no microgaps, which would lead to casting edges and the like that would require postprocessing, form in this region.

[0060] As also shown in FIG. 3, both on the part of the first heating device 7 and the second heating device 8, the heating elements 17 and 20, respectively, are laid more closely at the periphery than in those regions of the heating devices 7, 8 which adjoin thereto. This makes it possible to introduce a greater quantity of energy, that is to say more heat, into the polymer compound in the critical peripheral region, meaning that the metal layers 5, 6 and thus also the casting compound are heated more rapidly there compared with the rest of the surface. This therefore polymerizes to completion at the periphery sooner and more rapidly than within the rest of the volume. Since no movability of the second metal layer 6 resulting from the compression of the intermediate layer 9 is provided at the periphery, any shrinkage there cannot be compensated by such tracking of the metal layer 6. Since, however, the casting compound within the rest of the cavity volume is still liquid while it is already beginning to polymerize to completion at the periphery, the liquid casting compound accordingly pushes into the peripheral region, such that any shrinkage there is immediately compensated again by inflowing casting compound. This means that a defect-free periphery can be produced.

[0061] Beyond the compacted laying of the heating elements, the specific peripheral heating can also be individually designed such that the heating elements laid there can also be supplied with heating fluid or energized individually as separate heating circuit, such that a temporally different heating mode can also be effected, or for example can have a hotter fluid conducted therethrough or be more strongly energized, etc.

[0062] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.