CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage of International Application No. PCT/EP2017/081720, filed Dec. 6, 2017, and claims benefit to German Application No. 10 2016 124 061.3, filed Dec. 12, 2016, both of which are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a disposable mold core for producing a fiber-reinforced component having a hard supporting core manufactured from granulate, in particular from a mineral base material, glass, ceramic, and/or sand, and a binder. The disclosure also relates to a method for producing a fiber-reinforced component in which reinforcement fibers, in particular as woven fabric, non-crimp fabric and/or braided fabric, are placed on a disposable mold core together with a matrix, and the matrix is hardened in a molding tool by increasing the temperature and/or pressure. Furthermore, the disclosure includes a fiber-reinforced component, especially an undercut and/or hollow component, with a base body developed at least partially from reinforced fibers that form a woven fabric, non-crimp fabric and/or braided fabric, and a hardened matrix. Additionally, the disclosure includes a disposable mold core for producing a fiber-reinforced component with at least two segments that can be rinsed off it with a solvent after the component has been produced. Moreover, the disclosure includes a manufacturing process for a disposable mold core to produce a fiber-reinforced component in which at least two segments are developed and the mold core consists of these two segments.

BACKGROUND

Mold cores that can be rinsed off for the production fiber-reinforced components are known from the general state of the art. The disadvantage with such mold cores is that the manufacturing of the mold core and of the component itself is very expensive.

SUMMARY

Therefore, the task of the present disclosure is to create a disposable mold core that can be economically produced either itself or the component produced with it.

The task is solved by disposable mold cores used to produce components, its manufacturing processes and a component according to the characteristics of the independent claims.

A disposable mold core to produce a fiber-reinforced component with a hard support core produced from a granulate and a binder is suggested. The granulate can be a mineral base material, glass, ceramic and/or sand. The component can also be a structural hollow component, for example.

According to the disclosure, the support core has a hard shell made from the binder and granulate. The hard shell provides stability to the mold core, so that reinforcement fibers can be placed on the shell to produce the component.

In addition, the support core has a binder-free inner core formed by granulate. Compared to the shell, it can be detached quicker and/or easier after the fiber-reinforced component is manufactured, compared to the shell. For example, the core can be shaken out of the shell. Thus, the granulate is preferably free-flowing. As a result of that, the granulate can be easily removed from the component, thereby lowering manufacturing costs. If the high pressure makes the granulate stick together, it must first be loosened, which can be done with a liquid and/or mechanically.

In an advantageous further development of the disclosure, the granulate of the inner core is loose. Additionally or alternately, the granulate of the inner core can also be compressed and/or sticking together. As a result of that, the individual granulate grains lie tightly close together and the granulate can therefore absorb pressure forces in the interior of the core, which occur for example when the reinforcement fibers are placed on the mold core with the matrix or when the component is being produced. This prevents a deformation of the mold core, so that the component is also produced without deformations.

It is likewise advantageous if the support core is produced in a rapid prototyping process in which the support core can be printed, for example. In this case, the rapid prototyping process is an economical and fast method to produce the support core.

It is also advantageous if the binder concentration decreases from an outer surface of the support core towards its interior. Here, the concentration can also decrease towards the middle of the cross section. In addition, the concentration can decrease linearly, parabolically and/or exponentially. For example, the concentration can decrease here from 100% on the outer surface all the way down to 0% in the interior.

It is furthermore advantageous if the shell is less than 5 mm thick. However, the shell can also be less than 2 mm thick and therefore, the shell becomes stable on the one hand and a lot of granulate without binder is in the core, on the other hand, so an especially large quantity of granulate can be shaken out after the component is produced.

Here, it is also advantageous if the shell has a thickness of 3% to 10% of the respective diameter on the corresponding place of the mold core. This makes it possible to save binder to lower costs while maintaining the stability of the mold core.

It is also advantageous if the shell has a separating layer that seals off the support core towards the exterior. Here, the separating layer can be elastic and additionally or alternately be developed using a silicone and/or plastic layer. This can prevent the matrix from diffusing into it while the component is being produced. During the manufacturing of the component, the matrix is placed on the mold core together with the reinforcement fibers, wherein the matrix is combined with the reinforcement fibers under higher pressure and/or temperature to bind to the component. The separating layer prevents the matrix to diffuse into the mold core, at least partially. The diffusing into it is detrimental because otherwise the matrix will combine with the granulate and the latter can only be removed from the component with difficulty.

It is furthermore advantageous if the binder can be dissolved with a solvent, so that it can be rinsed off after the fiber-reinforced component has been produced. Additionally or alternately, the separating layer can also be soluble. The solvent can be an acid, a base, water and/or an alcohol, for example. As a result of that, the binder and/or the separating layer can be easily rinsed off from the component.

It is furthermore advantageous if the shell has at least one opening area in which the shell can be split open to form an opening. The shell can also have the opening from the outset. After manufacturing of the fiber-reinforced component, the loose core can trickle out through the opening. Here, the opening can be arranged on a front side of the mold core, for example. The opening allows the granulate and/or the shell to be very easily removed or rinsed off.

Moreover, a process for producing a fiber-reinforced component is suggested in which reinforcement fibers are arranged together with a matrix around a disposable mold core in order to develop a fiber-reinforced component. The reinforcement fibers can include a woven fabric, non-crimp fabric and/or braided fabric. The matrix is then hardened in a molding tool by increasing the temperature and/or pressure.

According to the disclosure, after the matrix has been hardened and while the mold core is still inside the component, at least one reinforcement element is pressed onto an external surface of the component under pressure. Only afterwards is the disposable mold core at least partially removed from the component. If the mold core is still in the component, it contributes to its stability, so that the reinforcement element can be pressed onto the component without deforming it.

Additionally or alternately, a mold core according to one or several of the characteristics described above and/or below is used, wherein the above-mentioned characteristics can be present individually or in any combination. The mold core also includes a hard shell and a binder-free and/or loose core. After the fiber-reinforced component is produced, the core is removed from the shell, especially rinsed off and/or shaken out. Since the core has been developed loose and/or without binder, it can be easily removed from the component. If owing to the high pressure, the granulate sticks together, it must be loosened first with a liquid and/or mechanically, for example.

In an advantageous further development of the disclosure, the shell—particularly after the core is removed—is rinsed off with a solvent. After the core has been shaken out, only the shell remains arranged in the component, which now creates a large attack surface for the solvent, allowing it to dissolve the shell especially quickly. Thus, a simple shaking out of the dissolved shell can likewise remove it from the component. Alternately, the shell can also remain in the component, however.

It is also advantageous if the reinforcement element is arranged around the disposable mold core together with the reinforcement fibers and the matrix. In this case, the matrix can still be unhardened. Additionally or alternately, the reinforcement element can include an unhardened molding material, such as a C-SMC (C-sheet molding compound). Only in a subsequent step can the matrix be hardened together with the reinforcement element or molding material. As a result of this, the reinforcement element can be firmly joined to the matrix during hardening and thus to the reinforcement fibers. Because of this, the reinforcement element and the matrix with the reinforcement fibers are stably, especially firmly, joined.

It is likewise advantageous if the reinforcement element is pressed onto the hardened matrix. In this process, the matrix can also be fully hardened. As a result of this, the component already has a certain stability so that the reinforcement element can be pressed onto to the component without damage. The reinforcement element can be molding material such as a C-SMC (C-sheet molding compound).

A fiber-reinforced component having a main body made at least partially of reinforcement fibers and a hardened matrix is furthermore suggested. The component can be, for example, an undercut and/or a hollow component. Here, the reinforcement fibers can form a woven fabric, non-crimp fabric and/or braided fabric.

According to the disclosure, the component is manufactured according to one or several process characteristics described above and/or below. Furthermore, the main body has on its external surface at least one reinforcement firmly joined to it. The reinforcement element serves to increase the stability or stiffness of the component.

Additionally or alternately, the component is developed as hybrid component, wherein a part of the main body is made from a molding material that includes a hardened matrix with loose reinforcement fibers. Additionally or alternately, the reinforcement element can also be made from the molding material. Here, the molding material can be easily pressed onto the component. In addition, the component can be easily manufactured, at least partially, from the molding material.

In an advantageous further development, the reinforcement element includes strengthening ribs and/or a reinforcement structure. The strengthening ribs can be easily and economically manufactured. The reinforcement structure makes the component very stable.

Additionally or alternately, it is advantageous if the reinforcement element is executed from a fiber composite and/or metal. In this case, the fiber composite includes a reinforcement fiber and a matrix. For example, the fiber composite can be made from the same reinforcement fiber/matrix mixture as the component. Thus, the fiber composite has essentially the same properties of the component, like the same temperature expansion. As a result of that, tensions occurring between the component and the reinforcement element due to a different temperature expansion, for example, are lowered. The fiber composite can also include a C-SMC (C-sheet molding compound) and form the molding material. In this case, the molding material can be placed particularly easily on the external surface and is economical.

It is additionally advantageous if a firm bond is developed between the matrix and the reinforcement element. Here, the reinforcement element can include a molding material, especially made of C-SMC. The firm bond considerably enhances the strength between the component and the reinforcement element.

It is furthermore advantageous if at least one fastening element like a threaded insert, sleeve, hook and/or a bore is arranged in and/or on the reinforcement element. This allows the fastening element to be arranged on the component with the reinforcement element and dispenses with the need to rework the component to arrange the fastening element on it.

A disposable mold core to produce a fiber-reinforced component with at least two segments is being suggested. After the component is produced, the at least two segments can be rinsed off it with a solvent and the mold core is removed from the component to reduce its weight. Moreover, the mold core can have one or several of the characteristics described above and/or below.

According to the disclosure, the disposable mold core includes at least one elastic and/or flexible compensatory element arranged between the two segments. The compensatory element connects both segments in such a relatively movable way to one another that a translational and/or rotational misalignment between the two segments can be compensated. The compensatory element makes it possible to compensate for measurement inaccuracies of the mold core or segments that can lead to the translational and/or rotational misalignment. If, for example, the rotational misalignment occurs between the two segments, they can be twisted against one another by means of the elastic and/or flexible compensatory element, thereby compensating for this rotational misalignment. Here, the compensatory element is stretched and/or compressed in areas, thus furthermore connecting the two segments. On the other hand, if the translational misalignment occurs, which is the case for example when the segments are too widely separated from one another, the compensatory element can be compressed to reduce the distance accordingly, which keeps the segments joined.

In an advantageous further development of the disclosure, the compensatory element is joined to the segment in a firm and/or interlocking way in one of its connecting areas. The firm bond can be easily created and is especially secure. Here, the connecting area can be arranged on the front side of the corresponding segment.

It is likewise advantageous if the two segments corresponding to one another firmly engage with their connecting areas. For example, they can engage in such a way that they form an articulated joint between them. The articulated joint can also be executed as a hinge and/or ball joint. For example, a rotational misalignment can be compensated especially easily with the ball joint because it allows a rotation by three rotational axes oriented orthogonally to each other (in a Cartesian coordinate system, they can be the x-, y-, and z-axis) to compensate for the rotational misalignment. In addition, the ball joint can have a ball socket on one segment and a respective spherical head on the corresponding segment, wherein the spherical head is pivot mounted in the ball socket.

It is also advantageous if the compensatory element is made of an elastomer, an unhardened thermoplastic, an unhardened thermoset and/or an adhesive that is still elastic and/or flexible in a solidified state. The thermoplastics can be polyvinyl alcohols, for example. Here, an elastomer has the elastic and/or flexible properties.

The unhardened thermoplastics and/or unhardened thermosets can be used, for example, to fix the two segments in place. To achieve this, the thermoplastics and/or thermosets are not fully hardened yet while the two segments are being assembled so that they can be easily arranged between the segments.

In order to join the two segments, the thermoplastics are for example heated first, arranged between the segments and then cooled off once again. The thermoplastics can be heated to become fluid again after the component is produced, for example, so they can be rinsed off the component. The thermoplastics can be polyvinyl alcohols, for example.

The thermosets can likewise be heated first, arranged between the segments and then cooled off once again. Thermosets are here more heat-resistant than the thermoplastics and/or elastomers, for example.

Additionally or alternately, the compensatory element can also be made from an adhesive that is still elastic and/or flexible in a solidified state. In this case, the adhesive can be liquid to viscous, for example, so it can be easily arranged between the segments. After some time, the adhesive then solidifies by itself without needing additional treatment, thereby simplifying the manufacturing of the mold core.

In this process, mixtures between elastomer, thermoplastic, thermoset and/or adhesive can also be used as compensatory element.

It is likewise advantageous if the compensatory element includes an expansion material that expands when the temperature is increased, so that the two contiguous segments can be pressed apart during the manufacturing of the component. As a result of this, the segments can be pressed against an inner side of a molding tool while the component is being produced. This allows the component to have a more accurate shape and reduces, for example, the play of the mold core in the molding tool.

It is advantageous here for the expansion material to be made of wax, silicon, plastic, fat and/or a low-melting alloy. For example, a wax, silicon and/or fat can be easily rinsed off the fiber-reinforced component.

It is furthermore advantageous if the segments are executed as one single piece, are separated from one another and/or are in a row in longitudinal direction of the mold core. The one-piece execution of the segments allows them to be manufactured very easily and quickly. Owing to their separation, the segments cannot interlock. If the segments are longitudinally aligned in rows next to one another, the mutually connecting areas of the segments are kept as small as possible, thus economizing on compensatory elements.

It is also advantageous if the segments are made from one granulate that includes a granulate and/or binder. The segments can be made, for example, from a porous granulate and/or with one having spaces, thereby economizing on segment weight. In addition, the granulates can be made from a mineral base material, glass, ceramic and/or sand, all of them easily processed.

It is furthermore advantageous if the binder of the segments and/or at least partially the compensatory element, especially the expansion material, can be dissolved with a solvent so that the mold core can be rinsed off the component after it has been produced. The solvent can be, for example, an acid, a base, water and/or an alcohol. The binder, the compensatory element and/or the expansion material can therefore be rinsed off the component with a solvent as part of an easy work step.

It is likewise advantageous if the mold core has rinse-off hollow space extending, at least partially, through the segments and/or the compensatory element by means of which the mold core release can be accelerated. The solvent can be introduced purposefully in the rinse-off hollow space to dissolve the segments on all sides and/or the compensatory element, as a result of which the mold core is rinsed off faster.

A manufacturing process for a disposable mold core to produce a fiber-reinforced component is also suggested. Here, the mold core can be executed according to at least one of the characteristics described above and/or below. At least two segments are developed in the manufacturing process. The mold core will then be assembled from these two segments.

According to the disclosure, the segments are aligned with respect to one another and subsequently firmly joined to each other in a relatively movable way with at least one elastic and/or flexible compensatory element. As a result of this, a translational and/or rotational misalignment between the two segments can be compensated. A measurement inaccuracy or manufacturing tolerance of the mold core or segments can lead to a translational and/or rotational misalignment, which leads to a defective component. For example, the translational misalignment can develop when the segments are too closely separated from one another. The component produced with such a mold core would have dimensions that are too small. By means of the elastic and/or flexible compensatory element, the two segments can be aligned and joined in such a way that this translational misalignment is compensated. To do this, the compensatory element can also be stretched and/or compressed in order to compensate for the translational and/or rotational misalignment, while still connecting the segments.

In an advantageous further development of the manufacturing process, the mold core is produced as one single piece and then split into the segments. This allows one, for example, to first check whether and how the translational and/or rotational misalignment of the mold core has been developed. Afterwards, the mold core can be split into advantageous segments, so that as few segments as possible result from compensating for the manufacturing tolerance. Alternately, the segments of the mold core can be produced separately from one another. Contrary to a larger mold core, smaller segments can be manufactured with greater accuracy, thereby reducing measurement inaccuracy is reduced beforehand.

The mold core or the segments can be manufactured by means of a core-shooting and/or rapid prototyping process, for example.

It is furthermore advantageous if a compensatory material is introduced in a free space between the two segments in order to develop the compensatory element. Here, the compensatory material can be injected, sprayed on and/or spread. Moreover, the compensatory material can be a chemically hardening and/or a physically setting adhesive. A chemically hardening adhesive can be, for example, a two-component adhesive. A physically setting adhesive can harden, for example, with ultraviolet rays.

It is also advantageous if the compensatory material is solidified for developing the flexible and/or elastic compensatory element. The compensatory element allows the translational and/or rotational misalignment to be compensated.

