The invention refers to an extruded ceramic product and at the same time also to a process for manufacturing such product as well as to a device for fashioning such product during extrusion.

Pursuant to the International Patent Classification, such invention belongs to processing of mineral materials, namely to shaping of ceramic compositions, and in particular to processing of such shaped products.

The purpose of the invention is to enable manufacturing of an extruded ceramic product, which should in particular serve as electric insulating base for electric or electronic components consisting of electric conductive wire windings, in particular resistors, coils or the like, wherein said product should be manufactured by means of extruding, and should be on its surface furnished with a plurality of ribs and grooves arranged in a direction of said windings i.e. transversally with respect to a direction of extruding, by which said windings of wire are prevented from displacement. A further purpose of the invention is also to improve process of extruding, which should enable manufacturing of said product. Simultaneously, the purpose of the invention is also to create a device, by means of which each ceramic product with previously mentioned features could be realized.

A fashioned product is disclosed in WO2010/015531 Al together with a process of manufacturing thereof.

The present invention refers to an extruded ceramic product, namely to a compact product with either a tubular or a continuous cross-section, which is defined by means of its longitudinal axis and each corresponding transversal circumference, the shape and dimensions of which remain essentially unchanged along the complete length of said product.

The invention provides that such product is corrugated within at least one surface area, which has a constant width and extends in a direction of the longitudinal axis of said product, namely furnished with a sequence of alternating repeated and equidistantly arranged grooves and ribs which are available along the complete length of said surface area with constant width and extend in the transversal direction of said product, namely at least approximately perpendicular with respect to said longitudinal axis. In the context of the previously mentioned features according to the invention it is also preferred, if said product is corrugated, namely furnished with said along the longitudinal axis of the product arranged and periodically repeated grooves and ribs, on two surface areas with the constant width and being located diametrically with respect to said longitudinal axis. Moreover, in the context of the previously mentioned features according to the invention it can be also foreseen that such product is corrugated, namely furnished with said along the longitudinal axis of the product periodically repeated grooves and ribs, on more than two surface areas with the constant width, and are located around said longitudinal axis apart from each other.

In this, said grooves and ribs may either extend linearly in a direction perpendicularly or in an inclined direction with respect to said longitudinal axis of the product, but in general they may also be non-linear, under provision that they still extend equidistantly with respect to each other.

A preferred product in accordance with the previously mentioned features is an electric insulating base for an electric component with at least one winding of a wire consisting of at least partially electric conductive material, which is helically wound along the longitudinal axis thereof.

In accordance with a further aspect of the invention, a device for manufacturing of an extruded product is foreseen, namely a device for fashioning such ceramic product during the stage of extruding, namely shaping prior to final hardening thereof, wherein such device is generally adapted for passing-through and shaping of each appropriate semi-solid pastose material, which is suitable for manufacturing of said ceramic product, in a direction of its longitudinal axis, and wherein such device is furnished with an inlet opening, which enables said material suitable for manufacturing of said product to be fed into said device, a forming area, in which said material suitable for manufacturing of said product is shaped in the sense of assuring each desired circumference, the shape and dimensions of which remain essentially unchanged along the complete length of said product, as well as an outlet opening, through which said material with each desired shape of its circumference is extracted from said device. The invention provides that such device comprises at least one forming roller, which is freely rotatable around its axis extending perpendicularly with respect to said longitudinal axis of said device and which is embedded in the area of said outlet opening and is on its circumference furnished with periodically repeated grooves and ribs, wherein at least said ribs protrude into the area of a hollow cross- section of said outlet opening of the device. The invention generally provides that such device may comprise two with regard to said longitudinal axis essentially diametrically opposite located forming rollers, or optionally also at least three around said longitudinal axis and apart from each other arranged forming rollers.

In this, said grooves and said ribs may either extend linearly in a direction along the axis, around which each forming roller is rotatable, or optionally in a direction inclined with respect to the said axis, wherein the invention also provides a possibility that said grooves and said ribs can also be non-linear, but still extend at equal distances apart from each other.

In accordance with a still further aspect to the invention, a process for manufacturing of an extruded ceramic product, wherein such process comprises at least

i) preparing of a homogenous mixture of each required mineral ingredients including binders and other required additives for the purposes of manufacturing of each desired extruded final ceramic product;

ii) adjusting each desired physical properties of said mixture for the purposes of extruding due to forming said ceramic product with each desired transversal circumference, and in particular adjusting density, viscosity and plasticity thereof;

iii) extrusion by means of extracting said mixture in a suitable extruding appliance under each appropriate pressure achieved by means of a piston or a worm or any other suitable means through appropriate device along the longitudinal axis of said device, by which then the longitudinal axis of each semi-product and each final product is defined, wherein each semi-product is extracted by taking into consideration each pre-determined contractions expected during each subsequent processing steps, and wherein each desired shape and dimensions are given to said not yet hardened semiproduct, in particular each desired shape of the transversal circumference and each desired length as required to form each desired final product; and iv) hardening of such obtained and not yet hardened semi-product, in particular at increased temperature, which is adjusted with regard to each used mixture, for the purposes of forming each final extruded ceramic product with each desired physical properties, in particular electric insulation capability, density, rigidity and hardness.

Within such process, the invention provides that during said step iii) of extruding, said semi-product with the previously formed shape of its transversal circumference is at least on its one surface area, which extends along its complete length in a direction of its longitudinal axis and the width of which is constant along the complete length thereof, is exposed to impressing of a sequence of periodically repeated grooves and ribs, which extend essentially in a transversal direction with respect to said longitudinal axis of said semi-product or also of the final product, or of said extruding device, respectively.

It is also possible that at least two surface areas with periodically repeated grooves and ribs are formed during said step iii) of extrusion, wherein said surface areas are formed either simultaneously, or at least one of said surface areas is formed successively. In this, said grooves and ribs on each of said formed surface areas with said constant width extend equidistantly with respect to each other, and at the same time said grooves and ribs on each of said formed surface areas having said width may also be linear and extend either perpendicularly or in an inclined direction with respect to the longitudinal axis of the semi-product or a final product or said extruding device respectively, or may also be non-linear.

The invention will be described in detail on the basis of the attached drawings, wherein

Fig. 1 is a plan view of an extruded ceramic product;

Fig. 2 is a side view of an extruded ceramic product according to Fig. 1 ;

Fig. 3 is a device for extruding a product according to Figs. 1 and 2; and

Fig. 4 is a cross-section along the plane A - A according to Fig. 3.

An extruded ceramic product according to the invention is generally a compact tubular product 1, which is defined by its longitudinal axis 10 and each desired transversal circumference 100, the shape and dimensions of which remain unchanged along the complete length of the product 1 i.e. along said longitudinal axis 10. Due to excellent electric insulating properties, hardness and resistance against corrosion, temperature, moisture and other influences, such product is in particular suitable for use in the field of electricity and electronics, namely as a base for arrangement of windings of wire consisting of at least partially electric conductive material, by which then each desired electric component is established, like an electric resistor, a coil or the like.

The invention provides that the extruded ceramic products of the previously described art is furnished with at least one corrugated surface area 1 1, 1 Γ, which extends along its longitudinal axis 10 and has a width B, namely furnished with a sequence of periodically repeating grooves 1 1 1 and ribs 112, which are alternatively repeated along the complete length of said surface area 11, 1 Γ with the width B, and are on said product 1 directed transversally, namely perpendicularly with respect to said longitudinal axis 10 thereof.

Regarding the preferred embodiment of the invention, said product 1 is corrugated i.e. furnished with said grooves 1 1 1 and ribs 1 12 on two surface areas 1 1, 1 1 ', which are arranged diametrically opposite with respect to said longitudinal axis 10. In general, a further embodiment is possible, in which said product 1 is corrugated i.e. furnished with said grooves 1 1 1 and ribs 1 12 in more than two surface areas 11, 1 1 ', which are arranged around said longitudinal axis 10 apart from each other.

In this, said grooves 1 1 1 and ribs 112 extend either linearly or are slightly curved, however are still arranged at essentially uniform distance apart from each other.

During the practical use of such product 1, windings of wire in each electric or electronic component, which consist of an electric conductive material and which are not shown in the drawings, are helically wound around the product 1 and are placed over its surface with a pre-determined step along said longitudinal axis 10. Thanks to said grooves 1 11 and ribs 1 12, said windings are then securely prevented against any movement along said surface of the product 1 , by which establishing of contact between said windings is prevented even in the case of impacts or vibrations, to which such component is normally exposed, when it is mounted within a motor vehicle.

Due to its excellent electric insulating properties, hardness and resistance against corrosion, temperature, moisture and other influences, said product 1 is in particularly suitable for use in the field of electricity and electronic, especially as a base for bearing windings of wire consisting of at least partially electric conductive material, which then represent each particular electric component comprising at least one electric conductive winding, in particular an electric resistor, a coil or the like.

In accordance with a further aspect of the invention, a device 2 is foreseen, which is suitable for manufacturing of the previously described product 1 by means of extruding, namely a device for fashioning said ceramic product 1 during the stage of pre-forming before the stage of final hardening thereof.

Said device 2 is adapted for transferring and fashioning of an appropriately semisolid pastose material, which is suitable for manufacturing of said ceramic product, along the longitudinal axis 20 thereof. When observed in a direction along said longitudinal axis 20, such device comprises an inlet opening 21, which allows said material to be fed into it, a fashioning area 22, in which said material used for manufacturing of a product 1 is appropriately shaped and provided with each desired transversal circumference 100, the shape and dimensions of which remain essentially unchanged along the complete length of the product 1 , as well as an outlet opening 23, through which said material with each desired transversal circumference 100 is then extracted from said device 2. The invention provides that such device 2 comprises at least one forming roller 25, which is freely rotatable around its axis 250 extending perpendicularly with respect to said longitudinal axis 20 of the device, and which is embedded in the area of said outlet opening 23 and furnished with periodically repeated grooves 252 and ribs 253 arranged on the circumference 251 thereof, wherein at least said ribs 253 protrude into the hollow cross-section of said outlet opening 23 of the device 2. In general, such device may comprise two forming rollers 25, 25', which are located diametrically opposite with respect to said longitudinal axis 20, or optionally at least three forming rollers 25, 25', which are located around said longitudinal axis 20 and apart from each other.

In accordance with a still further aspect of the invention, a process for manufacturing of said extruded ceramic product is foreseen, which comprises at least the following steps:

i) preparing a homogenous mixture of each required mineral ingredients together with each required binders and other required additives which are necessary for manufacturing each desired ceramic product 1 ;

ii) adjusting each required physical properties of said mixture for the purposes of extruding thereof due to formation of said ceramic product 1 with each desired transversal circumference 100, in particular in respect of density, viscosity, plasticity or the like;

iii) extruding by means of exposing said mixture to compression within an appropriate extruding appliance and extracting said mixture under each required pressure from said device 2 in a direction of the longitudinal axis 20 of said device 2, by which each required semi-product is obtained and the longitudinal axis 10 both of each semi-product and also of each final product 1 is defined, wherein by taking into consideration each expected contractions during the subsequent stages of the process of manufacturing each desired dimensions and shape, in particular each desired transversal circumference 100 and each appropriate length, are given to each semi-product for the purposes of forming each desired final product 1 ; and iv) hardening of such obtained semi-solid semi-product, in particular at increased temperature, which is adjusted to each desired mixture, in order to form an extruded ceramic product 1 with each desired physical properties, in particular electric insulating capability, density, rigidity and hardness. The invention provides that during the step iii) of extruding, a sequence of periodically repeated grooves 1 1 1 and ribs 1 12 extending essentially in at least approximately transversal direction with respect to the longitudinal axis 10 of the semi-product or the final product 1 or also said extruding device 2, is pressed onto circumference 100 of said semi-product with previously formed transversal circumference 100 along at least one longitudinal area 1 1, 1 1 ', which extends along the complete length thereof in a direction of said longitudinal axis 10 and which has a constant width B.

It is also possible that several surfaces area 1 1, 1 1 ' are formed simultaneously or successively during the previously mentioned step iii), wherein said grooves 111 and ribs 112 in each of such formed areas 1 1, 11 ' are preferably equidistantly arranged and are optionally linear and extend either perpendicularly or inclined with respect to the longitudinal axis 10 of the product 1, although they can generally also be non-linear, but even in such case extend along the complete width B of each surface area 1 1, 1 1 ' and are uniformly distanced apart from each other.