SE2350435A1

SE2350435A1 - An extruded product, an extrusion device, and an extrusion method

Info

Publication number: SE2350435A1
Application number: SE2350435A
Authority: SE
Inventors: Kragh Mark J
Original assignee: Reliefed Ab
Priority date: 2023-04-13
Filing date: 2023-04-13
Publication date: 2024-10-14
Also published as: WO2024213525A1

Abstract

An extruded product is provided. The extruded product comprises an upper side (112) having an upper depression pattern (120) being defined by a first rotating die (3) in an extrusion process, and a bottom side (114) having a bottom depression pattern (130) being defined simultaneously as the upper depression pattern (120) in said extrusion process, said bottom side (114) being opposite the upper side (112). The upper depression pattern (120) comprises at least one upper depression (121) extending at least partly in a longitudinal direction of the extruded product (100), and the bottom depression pattern (130) comprises at least one bottom depression (131) extending at least partly in the longitudinal direction of the extruded product (100). The extruded product (100) further comprises at least one overlap area (140) at which the upper depression (121) at least partly overlaps the bottom depression (131).

Description

AN EXTRUDED PRODUCT, AN EXTRUSION DEVICE, AND AN EXTRUSION METHOD Technical Field The present invention relates to a method for producing extruded products, to an extrusion device, and to extruded products.

Background Extrusion is an industrial production process used to create products. In traditional extrusion the product material is pushed through a static die, whereby the cross-section of the resulting product will correspond to the cross-section of the die.

Another approach has been developed to allow more complex products to be produced by extrusion. The present applicant has made significant contributions to a technique called 3D-extrusion, in which process at least one rotating die is used for defining the final dimensions of the product. The rotating die may be provided with a surface pattern which is transferred to the surface of the product during production. Depending on the surface pattern, this allows for a varying cross-section of the final product. 3D-extrusion is performed by pushing or pulling the product material through a static passage whereby the product material is formed into a master profile. Immediately downstream the passage the master profile enters a channel being at least partly defined by the outer surface of the rotating die. While passing through the channel, the master profile is formed into a final shape defining the final product. The rotating die allows the final shaping to include providing patterns at the surface of the final product.

As 3D-extrusion is receiving substantial market interest, there is a need for implementing this technique to products which so far have been much too complex for extrusion processes. For example, an advanced topography has only been made possible by extensive post-processing, which for various reasons is costly and disadvantageous.

Hence, there is need for an improved manufacturing processes which provides a more versatile approach to the production of advanced products.

Summary It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. In particular, it is an object to provide an extruded product which has a surface area allowing the product to be used in high tech applications.

An idea of the present invention is to provide an apparatus and method for producing an extruded product with a dual side pattern configuration, as well as to provide the extruded product per se. Within the context of the specification, the term "dual side pattern configuration" is used to define a cross-section in which a depression pattern of the upper side of the extruded product overlaps a depression pattern of the bottom side of the extruded profile.

To solve these objects an extruded product, or profile is provided. The extruded product comprises an upper side having an upper depression pattern being defined by a first rotating die in an extrusion process, and a bottom side having a bottom depression pattern being defined simultaneously as the upper depression pattern in said extrusion process, said bottom side being opposite the upper side. The upper depression pattern comprises at least one upper depression extending at least partly in a longitudinal direction of the extruded product, and the bottom depression pattern comprises at least one bottom depression extending at least partly in the longitudinal direction of the extruded product. The extruded product further comprises at least one overlap area at which the upper depression at least partly overlaps the bottom depression.

The upper depression and/or the bottom depression may have a constant depth at the entire overlap area.

The depth of the upper depression, the depth of the bottom depression, and/or the total depth of the upper and bottom depressions may exceed half the maximum thickness of the extruded product at the at least one overlap area.

The upper depression may be aligned with the bottom depression in the length and/or width direction of the extruded product.

The minimum distance between the upper depression and the bottom depression may define a minimum material thickness of the extruded product, wherein said minimum material thickness may be less than half the maximum thickness of the extruded product at the at least one overlap area.

The upper depression pattern and/or the bottom depression pattern may be repetitive.

The upper depression pattern and/or the bottom depression pattern may have a varying extension in the longitudinal direction of the extruded product.

The upper depression pattern and/or the bottom depression pattern may have a varying extension in the width direction of the extruded product.

The bottom depression pattern may be defined by a second rotating die during the extrusion process.

The bottom depression pattern may be defined by a static die during the extrusion process.

The at least one overlap area may be configured to provide an increased surface area, improved wetting, reduced electrical resistance, and/or improved electrochemical properties of the extruded product.

The at least one overlap area may be configured to provide a structural spring element, an isogrid structure, an attachment or welding joint, and/or improved deformation control, thermal behaviour, acoustic properties, ﬂuid dynamics, opto-chemical properties, and/or adhesion of the extruded product.

The extruded product may form part of a heat exchanger, a cooler, a beam, a bumper, a wall, a sound absorbing panel, an automotive product, a battery, an anode, a cathode, a separator, a ﬂow battery module, an electrolyte, a fuel cell, a solar panel, a sandwich element, a drainage device, a de -gassing device, and/or a slip protection device.

The areal specific electrical resistance of the extruded product may be 0,06Q/cm2 or less.

The thermal conductivity of the extruded product may be at least 10 m-kg-s'3-K'1.

The extruded product may be made at least to some extent of a polymer, plastic, and/or metal, preferably the extruded product is at least to some extent made of a composite material.

The material of the extruded product may comprise graphite, preferably by 50% by weight or more.

According to a second aspect, an extrusion device is provided. The extrusion device comprises a static passage configured to form a product material into a master profile, and a channel arranged immediately downstream the passage. The channel is delimited by an outer surface of a first rotating die and an outer surface of a second die arranged opposite the first rotating die thereby forming a channel height between the first and second dies. The first rotating die comprises a first topographic pattern configured to define an upper depression pattem comprising at least one upper depression extending at least partly in a longitudinal direction of the extruded product, and the second die comprises a second topographic pattern configured to define a bottom depression pattern comprising at least one bottom depression extending at least partly in the longitudinal direction of the extruded product. The first and second dies define at least one overlap area at which the upper depression at least partly overlaps the bottom depression.

The second die may be a static die.

The second die may be a rotating die.

The first rotating die may be synchronized with the second rotating die.

The circumference of the first and/or second rotating die may be equal to the length of the resulting extruded product.

The circumference of the first and/or second rotating die may be different from the length of the resulting extruded product.

The channel may have a longitudinal extension in a production direction, and the rotational axis of each of the first and second rotating dies may be arranged at an angle relative to said production direction, preferably the rotating dies are arranged at an angle of 90°ﬂ:25° relative to said production direction.

At least the first rotating die may be provided with radially protruding ﬂanges at each longitudinal end.

The channel may be defined by a bottom area, an upper area, and two opposing side areas together delimiting the dimensions of the channel, wherein at least parts of two opposing areas may be formed by the lateral surface area of the first and second rotating die.

At least one further area may be defined by the lateral surface area of a further rotating die.

At least one of the bottom area, upper area, and the two opposing side areas may be defined by a static bearing surface.

The topographic pattern may comprise at least one protrusion, said protrusion being configured to form a separation notch in the extruded product and/or a significant local reduction of the thickness of the extruded product.

The significant reduction of the thickness of the extruded product may define a removable portion of the extruded product.

The at least one protrusion may extend across the entire width of the first and/or second rotating die, or across a part of the width of the first and/or second rotating die.

The protrusion may extend in a linear or curved manner across the width of the rotating die.

The extrusion device may further comprise an inlet configured to add a further material to the product material.

The inlet for adding a further material may be arranged upstream, at, or downstream the first and second dies.

The inlet may be configured to add a further material being a liquid or a solid material in the form of powder or particles.

The extrusion device may further comprise an adjustment mechanism configured to adjust the position of the first and/or second die thereby adjusting the dimensions of the channel.

The extrusion device may further comprise at least one die core in said channel, said die core forming a hollow portion of said extruded product.

According to a third aspect, an extrusion method is provided. The extrusion method comprises i) forming material by pressing or pulling a product material through a channel of an extrusion die, said channel being at least partly defined by the lateral surface area of at least a first rotating die and a second die arranged opposite the first rotating die, and ii) providing an upper side of the product material with an upper depression pattern being defined by the first rotating die. The method further comprises iii) providing a bottom side of the product material with a bottom depression pattern being defined by the second die, said bottom depression pattern being provided simultaneously with the first depression pattern. The upper depression pattem comprises at least one upper depression extending at least partly in a longitudinal direction of the extruded product, and the bottom depression pattern comprises at least one bottom depression extending at least partly in the longitudinal direction of the extruded product, wherein the extruded product further comprises at least one overlap area at which the upper depression at least partly overlaps the bottom depression.

Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings.

Within this specification some specific terms are used, which are defined in the following.

Extrusion: Procedure in which a material under pressure is pressed through a proﬁle shaping tool (also called die) with hole(s) that defines the outgoing materials cross-section and appearance.

Pultrusion: Procedure in which a material under pressure is pulled through a proﬁle shaping tool (also called die) with hole(s) that defines the outgoing materials cross-section and appearance.

Dynamic extrusion: Procedure in which a material under pressure is pressed through a tool with rotating forming members (dies) that can give the material a diverse cross-section and/or appearance in the form of e. g. patterns on one or more surfaces and dimensional changes in cross-sectional area and/or material thickness.

Dynamic pultrusion: Procedure in which a material under pressure is pulled through a tool with rotating forming members (dies) that can give the material a diverse cross-section and/or appearance in the form of e. g. patterns on one or more surfaces and dimensional changes in cross-sectional area and/or material thickness.

Die: Generally, the name used by professionals for profile forming tools.

Rotating die: Rotating profile-shaping part of the tool for dynamic extrusion/pultrusion.

Bearing surface: The surface of an extrusion die in the smallest cross- section that the extruded material is forced through under pressure and thus constitutes the surface to finally define the cross-section and appearance of the formed material.

Static bearing surface: A solid bearing surface the extruded material is forced to pass at a relative speed of outgoing material speed. Because it is static, there is a speed difference between the static bearing surface and the extruded material, resulting in friction and heat. By regulating the length of the bearing surfaces it is possible to regulate the total amount of friction and thus the pressure, balance, and speed of the outgoing material.

Rotating bearing surface: A rotating bearing surface is a surface of the rotating die that defines the cross-section of the formed material, allowing for pattem generation as well as material thickness variations. A rotating bearing surface in general generates much less resistance and friction against the ﬂowing material than a static bearing surface, which previously has created major problems with the imbalance between the different parts of the cross-section of the formed material, and which is defined by all bearing surfaces of the entire die. This has often resulted in process breakdown at start up.

Pre-bearing (surface): The surface area that the extruded material passes just before it enters the area of the rotating die and its rotating bearing surface. The pre-bearing brings down the material cross-section so much so that the subsequent rotating die will not have to take up unnecessarily large forces from the formed material. Pre-bearing has in combination with upstream material shaping a central role for control and/or regulation of material ﬂows through the die.

Dynamic extrusion and dynamic pultrusion: The process of forming (ceramic) material by utilising rotating dies integrated in extrusion dies. The extrusion die has one or more rotational dies. The cross-sectional profile of the formed material may optionally be defined upstream of where the material to be formed reaches the rotating die whose outer circumference, i.e. the lateral surface area, defines a rotating bearing surface that finally def1nes the appearance and cross-section of the formed material in conjunction with other bearing surfaces, rotating and/or static, in the die.

Pattern: Any structural configuration being transferrable from a die to an extruded material. A pattern may be macroscopic, i.e. visible by the human eye, or microscopic. A pattern may further extend across the entire formed material, or across only a very small part of it. Typically, although not required, a pattern is a topographic configuration. Examples of patterns comprised within the context of this specif1cation are thickness variations of the formed material, reinforcement ribs, channels, and macro as well as micro structures. Even an entirely smooth surface is herein considered to define a pattern.

Brief Description of the Drawings Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which Fig. 1 is a top view of a series of extruded products according to an example.

Fig. 2a is a cross-sectional view of an extrusion device according to an example.

Fig. 2b is a cross-sectional view of an extrusion device according to a further example.

Fig. 3 is a cross-sectional view of a schematic setup of rotating dies in an extrusion device according to an example.

Fig. 4a is a cross-sectional view of an extruded product according to an example.

Fig. 4b is a cross-sectional view of an extruded product according to another example.

Fig. 4c is an isometric view of an extruded product according to an example.

Fig. 5 is an isometric view of parts of an extrusion device according to an example.

Fig. 6a is an isometric view of an extruded product according to an example.

Fig. 6b is a cross-sectional view of the extruded product shown in Fig. 6a.

Fig. 7 is an isometric cross-sectional view of an extrusion device according to an example, with a resulting extruded proﬁle.

Fig. 8a is a front view of an extruded product, showing the upper side.

Fig. 8b is a rear view of the extruded product, showing the bottom side.

Fig. 8c is a cross-sectional view of the extruded product shown in Figs. 8a-b.

Fig. 9 is an isometric view of an extrusion device according to an example.

Fig. 10 is a cross-sectional view of an extrusion device according to an example.

Fig. 11 is a schematic view of a method according to an example.

Detailed Description Starting in Fig. 1, an extruded product 100 is shown. The extruded product 100 is in the form of an extended profile, being produced continuously by an extrusion device and/or by an extrusion method as will be further described below.

The extruded product 100 may be produced as a linear array of consecutive product segments 110. The product segments 110 are preferably connected to each other, but may be easily separated in order to form individual extruded products.

The extruded product 100 comprises an upper side 112 and a bottom side 114 (not shown). The upper side 112 forms a first side being provided with a first or upper depression pattern 120. The upper depression pattern 120 is defined by a first rotating die during an extrusion process. The bottom side 114 forms a second side being provided with a bottom depression pattern 130 (not shown). The second side 114 is opposite the first side 112. The upper depression pattern 120 comprises at least one upper depression 121 extending at least partly in a longitudinal direction of the extruded product 100, and the bottom depression pattem 130 comprises at least one bottom depression 131 extending at least partly in the longitudinal direction of the extruded product 100.

The extruded product 100 further comprises at least one overlap area 140 at which the upper depression 121 at least partly overlaps the bottom depression 1 3 1 .

An extrusion device 1 for producing the extruded profile 100 is shown in Figs. 2a and 2b. Starting in Fig. 2a, Starting in Fig. 2, the extrusion device 1 is configured to process (i.e. form) any suitable material in a production direction PD. The material is preferably a plastically deformable material and/or a viscoelastic material and/or a plastically deformable material with elastic property and/or a viscoplastic material with elastic property.

The material may be designed to have a specific electrical resistance, preferably in the range of 0,06 Q/cmz or below.

The material may further be designed having a thermal conductivity being at least 10 m-kg-s'3-K'1.

In a preferred example, the material is a composite material. Such example may be realized by a composite material having an addition of graphite, for example the material has a graphite content of at least 50% by weight, such as 60% by weight or more.

Another preferred example could be aluminium.

The device 1 comprises a first rotating die 3, extending in a radial R direction and a width direction X, having two opposite first and second side walls and an outer circumferential (lateral) surface area 4 extending in the width direction X between the side walls. The rotating die 3 has the shape of a cylinder.

The device 1 further comprises a material definition zone 7 having a longitudinal direction Y coinciding with the production direction PD, a height direction Z and a width direction X being perpendicular to the height direction Z. The material definition zone 7 comprises a channel 10. In the device 1 shown in Fig. 2a, the channel 10 is preceded (in the production direction PD) by a passage 9.

The passage 9 is circumferentially delimited by one or more walls 11 to form a closed circumference for the ceramic material. The channel 10, arranged immediately downstream the passage 9, is at least partly defined by the lateral surface area 4 of the rotating die 3. The channel 10 is further defined by a counter-bearing 14, arranged opposite the rotating die 3, and opposing first and second channel portion side walls extending between the rotating die 3 and the counter-bearing 14.

In the shown example the counter bearing 14 is formed by a circumferential (lateral) surface area 6 of a second rotating die 5, also extending in a radial R direction and a width direction X, and having two opposite first and second side walls at each side of the outer circumferential (lateral) surface area 6. The second rotating die 5 also has the shape of a cylinder.

The first and second rotating dies 3, 5 are rotatable about a respective axis extending across the production direction PD and arranged to allow the lateral surface areas 4, 6 to, while the rotating dies 3, 5 rotates, exert a pressure onto a surface of the material when fed through the material definition zone 7.

According to the embodiment shown in Fig. 2a, the passage 9 is configured to deform the material into a master profile 36 having a maximum height H1 at a predetermined feeding rate dependent on the material and minimum cross-sectional area with a first maximum height D1 when exiting the passage 9.

The channel 10 is configured to further deform the material into a final shape 37 having a minimum height H2 by the rotating dies 3, 5 being configured to apply increasing pressure on the master profile 36. For this, the first rotating die 3 is configured at a minimum distance D2 from the counter bearing 14, i.e. the second rotating die 5, dependent on a maximum allowable pressure applied by the rotating dies 3, 5 at the position of that minimum distance D2. The maximum allowable pressure corresponds to the maximum difference in height of the master profile 36 and the final profile 37 and depending on a specific topographic pattern on the lateral surface area 4, 6 of the rotating dies 3, 5.

The maximum allowable pressure is also dependent on the viscoelastic and viscoplastic properties of the material and thus a difference between the final height H3 of the formed material and the height H2 immediately after the channel 10, due to the elasticity of the material.

According to one example, the passage 9 is formed between at least two side walls 11; a top pre-bearing and an opposing bottom pre-bearing, wherein the top pre-bearing is arranged above the opposing bottom pre-bearing in the height direction Z. The top pre-bearing and/or the bottom pre-bearing may comprise a wake element.

Typically, the wake element protrudes in a direction from the side wall into the passage 9. According to one example, the wake element protrudes in the height direction from the side wall into the passage. The wake element can be designed depending on material elasticity giving the correct height of the master profile when entering the channel 10. Here, elasticity refers to the material swelling after having been pressed into shape in the passage 9. The wake element creates a wave form in the material when having passed the wake element.

One advantage of the device 1 is that maximum load is controlled in both the passage 9 and in the channel 10 which gives the possibility to design the extrusion device 1 dependent on the material to be processed, as well as on the desired process speed. Controlling the maximum load dependent on material to be processed allows for a production rate with high quality output and reduces risk for e. g. rupture due to a too high stress on the material. 11 According to the example shown in Fig. 2a, the extrusion device 1 receives material; this material is formed in the passage 9 into the shape of a master profile 36 and directly thereafter the material is formed in the channel 10 into the shape of the final product 37. Fig. 2a also shows that the final product 37 has a lesser height H1 than the height H2 of the master profile 36 due to further pressure on the master profile 36 in the channel 10. Fig. 2a also shows that the formed material may have a lesser height H3 than the height H1 of the final profile 36 due to shrinking when cooling down from the final profile 37, if the forming is performed at elevated temperatures.

As is further shown in Fig. 2a the extrusion device 1 may comprise a pulling and stretching device 54 arranged downstream the channel 10 and being configured to pull the material in the production direction PD when exiting the channel 10. One advantage is that the pulling and stretching device 54 dynamically can stretch the material during its forming, e. g. in order to obtain an equidistant pattern in the production direction PD of the formed material. The pulling and stretching device 54 can further be used to guide the formed material in the width and/or height direction.

The pulling and stretching device 54 can be any type of device that comprises means for gripping the formed material and means for pulling. According to one example, the pulling and stretching device 54 comprises controlling means 55 for controlling the pulling force applied to the formed material. The controlling means 55 may comprise sensor(s) 56 and/or may be connected to sensor(s) 56 that supervises the state of the formed material. The sensor(s) comprises means for sending analog and/or digital information to the controlling means. The information relates to the state of the formed material and the controlling means 55 is configured to process the information for controlling the pulling and stretching device.

Fig. 2a further shows an initial zone A where the material is pressed into the passage 9 either by a device (not shown) exerting an external pressure in the production direction PD, i.e. extrusion, and/or by the material being dragged through the passage 9 by a device (not shown) dragging the material in the production direction PD, i.e. pultrusion.

Zone A of the extrusion device 1 comprises a funnel shaped opening 43 where the material changes from an initial form having a larger cross-section than the passage 9. The shape of the opening can however vary depending on the type of material, temperature and device pressing the material. 12 Zone B is arranged directly after zone A, wherein zone B corresponds to the longitudinal extension of the passage 9 and where the formation of the master profile 36 takes place, as a result of the material changing form due to the pressure exerted on the material from the side walls 11 of the passage 9 when the material moves through the passage 9.

Zone C is arranged directly after zone B, wherein zone C corresponds to the longitudinal extension of the channel 10 and where the formation of the final profile 36 takes place, as a result of the material changing form due to the pressure exerted on the material from at least the rotating die 3 and the opposing counter bearing 14 (i.e. the second rotating die 5) of the channel 10.

Zone D is arranged directly after zone C, wherein zone D corresponds to a section of the production line after channel 10 and where the material optionally starts to cool down (if the extrusion process is performed using elevated temperature). In such case the final profile 36 starts to change form due to shrinking as a consequence of the temperature drop. It should be noted that shrinkage can also occur due to drying of the formed material. In zone D, the final profile 37 can be subject to various production measures for achieving desired properties of the formed material, such as cooling, heating, stretching, compressing, etc. in order to change the final profile 37 into a desired shape with desired material properties.

In a preferred example, the final profile 36 is cooled relatively rapidly immediately after extrusion. Such rapid cooling may e. g. be performed in zone D, preferably between 0-100 cm from the end of zone C or within a few seconds after extrusion.

Rapid cooling may be performed by quenching, i.e. using water, air, or any other suitable medium to obtain fast reduction in temperature, and optionally also to obtain specific material properties of the final profile 36. Especially for plastic or polymer materials, quenching may be advantageous in order to rapidly f1xate the geometry of the final profile 36.

For aluminium rapid cooling will provide increased strength properties, e. g. by quenching.

The length of zone D typically depends on material properties and a working environment surrounding the material in zone D. The material properties are e. g. heat dissipation and the mass of the material to be cooled down. For example, a thinner material cools down faster than a thicker material. The working environment refers e. g. to ambient temperature and humidity. For 13 example, a warmer environment slows down the cooling process compared to a cooler environment.

Zone E is arranged directly after zone D, wherein zone E corresponds to a section of the production line where the material has dried or has cooled down to a predetermined temperature representing a temperature establishing the final form of the formed material and where no, or only an inf1nitesimal change of form will continue. The formed material has a height H3 in zone E being optionally less than the height H2 of the final profile 37.

It should be noted that for some materials it is possible to run the extrusion device 1 at room temperature, whereby little or no cooling is needed. Zones D and E will in such embodiment be very short, if at all necessary.

With reference to the extrusion device shown in Fig. 2a, and which will further be described in the following, the first rotating die 3 comprises a first topographic pattern and the second rotating die 5 comprises a second topographic pattem. A total height of the first and second topographic patterns may exceed the channel height D2.

Now turning to Fig. 2b another example of an extrusion device 1 is shown. The extrusion device 1 of Fig. 2b has many similarities with the extrusion device 1 of Fig. 2b, and these common features will not be repeated. However, in Fig. 2b the extrusion device 1 has no second rotating die. Instead the channel 10, arranged immediately downstream the passage 9, is at least partly defined by the lateral surface area 4 of the rotating die 3 and by a static counter-bearing 14 arranged opposite the rotating die 3. The channel height D2 is thus defined as the minimum distance between the lateral surface area 4 of the rotating die 3 and the static counter-bearing 14.

In the example shown in Fig. 2b, the rotating die 3 comprises a first topographic pattern and the counter-bearing 14 comprises a second topographic pattem. A total height of the first and second topographic patterns may exceed the channel height D2.

According to the various examples given herein, and as illustrated in Fig. 3 in a schematic and general manner, the extruded profile 100 has a first side 112 having an upper depression pattern 120 being defined by a first rotating die 3 during an extrusion process, and a second side 114 having a bottom depression pattem 130, said second side 114 being opposite the first side 112. The upper depression pattern 120 comprises at least one upper depression 121 extending at least partly in a longitudinal direction of the extruded product 100, and the bottom depression pattern 130 comprises at least one bottom depression 131 14 extending at least partly in the longitudinal direction of the extruded product. The extruded product further comprises at least one overlap area 140 at which the upper depression 121 at least partly overlaps the bottom depression 131.

These features of the extruded product 100 are made possible by means of the extrusion device 1. The product-forming channel 10 is delimited by the outer surface 4 of the first rotating die 3 and the outer surface 6 of a second rotating die 5 arranged opposite the first rotating die 3 thereby forming a channel height D2 between the first and second dies 3, 5. The first rotating die 3 comprises a first topographic pattern 60 of a first height X1 and the second die 5 comprises a second topographic pattern 70 of a second height X2, wherein a total height X1+X2 of the first and second topographic patterns 60, 70 does not exceed the channel height D2, thereby leaving a residual product thickness at the overlap area 140.

It should be noted that the second rotating die 5 could be replaced by a static counter-bearing 14, as described above with reference to Fig. 2b. In such case the counter-bearing 14 comprises the second topographic pattern 70 of a second height X2.

Examples of overlap areas 140 of extruded products 100 are shown in Figs. 4a and 4b. The first depression pattem 120 is made with a depth Y1, and the second depression pattern 130 is made with a depth Y2. In Fig. 4a the depth Y1 is greater than half of the maximum thickness T of the extruded product 100, such that Y1 > T/2.The depth Y2 is less than half of the maximum thickness T of the extruded product 100, such that Y2 < T/2. In particular, in the shown example Y1 > Y2. At the overlap area 140, the total depth Y1+Y2 of the first and second depression patterns 120, 130 does not exceed the maximum thickness T of the extruded product 100.

In Fig. 4a the bottom depression 131 is much more narrow than the upper depression 121.

In Fig. 4b the depth Y1 is greater than half of the maximum thickness T of the extruded product 100, such that Y1 > T/2. However, the bottom depression 131 has a varying depth; a greater depth Y2* is provided remote from the upper depression 121, while a lesser depth Y2 is provided to overlap the upper depression 121. The overlap area 140 is thus the area where the upper and bottom depressions 121, 131 are aligned, i.e. in the shown example the greater depth Y2* of the bottom depression 131 is arranged outside the overlap area.

In Fig. 4c another example of an extruded profile 100 is shown. The overlap area 140 extends across the entire, or at least across the majority, length of the extruded profile 100. The first and second depression patterns 120, 130 extend in the longitudinal direction of the extruded profile 100, i.e. in a direction being parallel with the production direction PD. In the shown example, longitudinal upper and bottom depressions 121, 131 are overlapping along the entire length of the extruded product 100.

In Fig. 5 another example of an extruded profile 100 is shown, exiting a channel 10 formed between two opposing rotating dies 3, 5. The rotating dies 3, 5 are provided with respective topographic patterns 60, 70. These patterns 60, 70 are wave-like structures, forming corresponding depression patterns 120, 130 in the extruded product 100. Hence, in this example the depression patterns 120, 130 extend both in the longitudinal direction and in the cross-wise direction.

Preferably, at the overlap area 140, i.e. the area of the extruded product 100 being provided with aligning depressions 121, 131 on both sides, the total depth of the ﬁrst and second depression patterns 120, 130 does not exceed the maximum thickness of the extruded product 100.

Figs. 6a and 6b show an extruded profile 100 according to an example. The extruded profile 100 has hollow edge structures 150, and the overlap area 140 extends cross-wise between the edge structures 150. At the overlap area 140, depression patterns 120, 130 overlap each other in the thickness direction such that upper and bottom depressions 121, 131 are aligned and overlapping.

In Fig. 7 another example of an extrusion device 1, and a resulting extruded profile 100, is shown. The extrusion device 1 comprises a passage 9 as has been described with reference to Figs. 2a and 2b, and a downstream channel 10 formed between two rotating dies 3, 5. Each rotating die 3, 5 is provided with a topographic pattern 60, 70 in the form of hexagon shapes, thereby forming an overlap area 140 (extending substantially across the entire extruded profile 100) in the extruded product 100.

In Figs. 8a-c another example of an extruded profile 100 is shown. The upper side is provided with an upper depression pattern 120, and the bottom side is provided with a bottom depression pattern 130. An overlap area 140 is defined as the joint area of the upper and bottom depression patterns 120, 130.

As can be seen in Fig. 8c the upper depression pattern comprises a number of upper depressions 121, and the bottom depression pattern comprises a number of bottom depressions 131. The upper and bottom depressions 121, 131 may or may not be identical. At the overlap area 140, the upper and bottom depressions 121, 131 overlap. 16 In Fig. 9 another example of an extrusion device 1 is shown. One or more of the static areas of the channel 10, i.e. the side areas and optionally the counter- bearing 14, is here replaced by one or more additional rotating dies.

Fig. 9 schematically shows an assembly of rotary dies including four rotary dies. The channel 10 is here defined by the first rotating die 3, a second rotating die 5 arranged opposite the first rotating die 3 and forming the counter- bearing 14, a third rotating die 34 replacing one of the side areas and a fourth rotating die 35 arranged opposite the third rotating die 34.

Fig. 9 is one example only. It would be possible to define the channel 10 by one more rotating dies 3, 5, 34, 35. For example, the channel 10 could be defined by two rotating dies 3, 5, 34, 35 while the remaining areas defining the channel 10 are static. As another example there is no need for the channel 10 to have a rectangular cross-section; the channel 10 could be defined by three areas forming a triangular cross-section, by six areas forming a hexagonal cross- section, etc. One or more, possibly all, areas of the channel 10 may be defined by a specific rotating die 3, 5, 34, 35. Each one of the rotating dies 3, 5, 34, 35 may have a specific topographic pattern on its lateral surface area, for imprinting a side of the formed material with a corresponding depression pattern.

The second, third and/or the fourth rotating die(s) 5, 34, 35 can be arranged in a similar way as the above described first rotating die 3 to create same or different depression patterns on two sides of the extruded product 100. The second, third and/or fourth rotating dies 5, 34, 35 can comprise annular recesses and/or ﬂange portions that can be arranged to cooperate with annular recesses and/or ﬂange portions of the first rotating die 3.

One or more of the rotating dies 3, 5, 34, 35 may be driven. According to one example, two or more rotating dies 3, 5, 34, 35 are synchronised. This has the advantage of feeding the material at the same speed through the channel 10. However, it could be possible to also use non-synchronous rotating dies 3, 5, 34, 35 in order to create friction and/or a special depression pattern and/or to compensate for material differences.

The extrusion device 1 can be arranged with a combination of textured and non-textured rotating dies 3, 5, 34, 35, as long as an overlap area 140 is formed as has been described above.

Fig. 10 schematically shows a cross-sectional side view of an extrusion device 1 comprising two opposing rotating dies 3, 5. Fig. 10 further shows that the extrusion device 1 comprises a passage 9 and a second passage 46 connected to the profile definition zone 7 upstream the channel 10 for feeding an additional 17 material to the channel 10, thereby forming a layered extruded product 100 with material from the passage 9. Fig. 9 further shows that the extrusion device 1 comprises a third passage 47 for feeding a third material to the profile definition zone 7.

According to one example, the third passage 47 is an extrusion- or pultrusion passage similar to the passage 9 arranged to work the material. According to one example, the passage 47 is a passage that is configured as a conveyer unit for conveying a material to the profile definition zone 7. Although not shown in Fig. 10, the second rotating die 5 is provided with a topographic pattem to form an overlap area as has been described above.

Now turning to Fig. 11, an extrusion method 200 is schematically shown. The extrusion method comprises forming 202 material by pressing or pulling a product material through a channel of an extrusion die, said channel being at least partly defined by the lateral surface area of at least a first rotating die and a second die arranged opposite the first rotating die. The extrusion method further comprises providing 204 a first side of the product material with an upper depression pattern being defined by the first rotating die, and providing 206 a second side of the product material with a bottom depression pattern being defined by the second die.

The upper depression pattern comprises at least one upper depression extending at least partly in a longitudinal direction of the extruded product, and the bottom depression pattern comprises at least one bottom depression extending at least partly in the longitudinal direction of the extruded product, wherein the extruded product further comprises at least one overlap area at which the upper depression at least partly overlaps the bottom depression.

Finally some general comments on extrusion products 100, extrusion devices 1, and extrusion methods 200 will be given. These comments are generally applicable, alone or in any combination, for all examples described herein.

Starting with the overlap area 140, it may extend across the entire extruded product 100 or across parts of the extruded product 100.

The topographic patterns 60, 70 of the extrusion device 1 as well as the resulting depression patterns 120, 130 of the extruded product 100 may be continuously or sequential. The patterns 60, 70 may extend in the centre of the dies 3, 5, and they may run longitudinally, cross-wise, or in any combination such as diagonal, zic-zac, back-and-forth zic-zac, helically. The patterns 60, 70 may be in the form of beads, bulges, isogrids, etc. and the resulting depression 18 patterns 120, 130 may form structures for facilitating knock-out, punch-out, or other forms of separation.

The extruded product 100 may comprise one or more overlap areas 140 forming increased surface area, improved wetting, reduced electrical resistance, or improved electrochemical properties.

The depression patterns 120, 130 may be in the micro scale or in the macro scale. The depression patterns 120, 130 may be symmetrical, or they may be designed to create a varying thickness in the extruded profile 100.

The extruded product 100 may be subject to post-processing, such as heating, curing, exposure to UV radiation, etc.

The extruded product 100 may be designed such that the overlap area 140 provides improvements for various product functions, such as structural spring elements, deformation control, thermal behaviour, acoustic properties, increased surface area for photovoltaic applications, ﬂuid dynamics, opto-chemical properties, isogrids, attachment points, welding joints, adhesion, etc.

The extruded product 100 may be used in various application, such as domestic appliances, heat exchangers, coolers, beams, bumpers, walls, sound absorbing panels, automotive, batteries, anodes and cathodes, separators, ﬂow battery modules, electrolytes, fuel cells, solar panels, light devices, sandwich elements, drainage, de-gassing, slip protections, etc. In one particular example, the extruded product is a bipolar plate for a fuel cell. It can also be a plate for a hydrolyser.

From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject- matter defined in the following claims.

Claims

1. An extruded product, comprising: an upper side (112) having an upper depression pattern (120) being defined by a ﬁrst rotating die (3) in an extrusion process, and a bottom side (114) having a bottom depression pattern (130) being defined simultaneously as the upper depression pattern (120) in said extrusion process, said bottom side (114) being opposite the upper side (112), Wherein the upper depression pattern (120) comprises at least one upper depression (121) extending at least partly in a longitudinal direction of the extruded product (100), and the bottom depression pattern (130) comprises at least one bottom depression (131) extending at least partly in the longitudinal direction of the extruded product (100), Wherein the extruded product (100) further comprises at least one overlap area (140) at Which the upper depression (121) at least partly overlaps the bottom depression (131).

2. The extruded product according to claim 1, Wherein the upper depression (121) and/or the bottom depression (131) has a constant depth at the entire overlap area (140).

3. The extruded product according to claim 1 or 2, Wherein the depth of the upper depression (121), the depth of the bottom depression (131), and/or the total depth of the upper and bottom depressions (121, 131) exceeds half the maximum thickness of the extruded product (100) at the at least one overlap area (140).

4. The extruded product according to any of the preceding claims, Wherein the upper depression (121) is aligned With the bottom depression (131) in the length and/or width direction of the extruded product (100).

5. The extruded product according to claim 4, Wherein the minimum distance between the upper depression (121) and the bottom depression (131) def1nes a minimum material thickness of the extruded product (100), Wherein said minimum material thickness is less than half the maximum thickness of the extruded product (100) at the at least one overlap area.

6. The extruded product according to any one the preceding claims, wherein the upper depression pattern (120) and/or the bottom depression pattern (130) is repetitive.

7. The extruded product according to any of the preceding claims, wherein the upper depression pattern (120) and/or the bottom depression pattern (130) has a varying extension in the longitudinal direction of the extruded product (100).

8. The extruded product according to any of the preceding claims, wherein the upper depression pattern (120) and/or the bottom depression pattern (130) has a varying extension in the width direction of the extruded product (100).

9. The extruded product according to any of the preceding claims, wherein the bottom depression pattern (130) is defined by a second rotating die (5) during the extrusion process.

10. The extruded product according to any of the preceding claims, wherein the bottom depression pattern (130) is defined by a static die (14) during the extrusion process.

11. The extruded product according to any of the preceding claims, wherein the at least one overlap area is configured to provide an increased surface area, improved wetting, reduced electrical resistance, and/or improved electrochemical properties of the extruded product (100).

12. The extruded product according to any of the preceding claims, wherein the at least one overlap area is configured to provide a structural spring element, an isogrid structure, an attachment or welding joint, and/or improved deformation control, thermal behaviour, acoustic properties, ﬂuid dynamics, opto-chemical properties, and/or adhesion of the extruded product (100).

13. The extruded product according to any of the preceding claims, wherein said extruded product (100) forms part of a heat exchanger, a cooler, a beam, a bumper, a wall, a sound absorbing panel, an automotive product, a battery, an anode, a cathode, a separator, a ﬂow battery module, an electrolyte, a fuel cell, a solar panel, a sandwich element, a drainage device, a de -gassing device, and/or a slip protection device.

14. The extruded product according to any of the preceding claims, wherein the areal specific electrical resistance of the extruded product (100) is 0,06Q/cm2 or less.

15. The extruded product according to any of the preceding claims, wherein the thermal conductivity of the extruded product (100) is at least 10 m-kg-s'3-K'

16. The extruded product according to any of the preceding claims, wherein the extruded product (100) is made at least to some extent of a polymer, plastic, and/or metal, preferably the extruded product is at least to some extent made of a composite material.

17. The extruded product according to claim 16, wherein the material of the extruded product (100) comprises graphite, preferably by 50% by weight or more.

18. An extrusion device, comprising a static passage (9) configured to form a product material into a master profile, and a channel (10) arranged immediately downstream the passage (9), wherein the channel (10) is delimited by an outer surface of a first rotating die (3) and an outer surface of a second die (5) arranged opposite the first rotating die (3) thereby forming a channel height between the first and second dies (3, 5), wherein the first rotating die (3) comprises a first topographic pattern (60) configured to define an upper depression pattern (120) comprising at least one upper depression (121) extending at least partly in a longitudinal direction of the extruded product (100), and the second die (5) comprises a second topographic pattem (70) configured to define a bottom depression pattern (130) comprising at least one bottom depression (131) extending at least partly in the longitudinal direction of the extruded product (100), wherein the first and second dies (3, 5) define at least one overlap area (140) at Which the upper depression (121) at least partly overlaps the bottom depression (131).

19. The extrusion device according to claim 18, wherein the second die (5) is a static die.

20. The extrusion device according to claim 18, wherein the second die (5) is a rotating die.

21. The extrusion device according to claim 20, wherein the first rotating die is synchronized With the second rotating die.

22. The extrusion device according to claim 20 or 21, wherein the circumference of the first and/or second rotating die is equal to the length of the resulting extruded product.

23. The extrusion device according to claim 20 or 21, wherein the circumference of the first and/or second rotating die is different from the length of the resulting extruded product.

24. The extrusion device according to any of claims 20-23, wherein the channel has a longitudinal extension in a production direction, and wherein the rotational axis of each of the first and second rotating dies is arranged at an angle relative to said production direction, preferably the rotating dies are arranged at an angle of 90°i25° relative to said production direction.

25. The extrusion device according to any of claims 18-24, wherein at least the first rotating die is provided with radially protruding ﬂanges at each longitudinal end.

26. The extrusion device according to any of claims 20-25, wherein the channel is defined by a bottom area, an upper area, and two opposing side areas together delimiting the dimensions of the channel, wherein at least parts of two opposing areas are formed by the lateral surface area of the first and second rotating die.

27. The extrusion device according to claim 26, wherein at least a part of at least one further area is defined by the lateral surface area of a further rotating die.

28. The extrusion device according to claim 26 or 27, wherein at least one of the bottom area, upper area, and the two opposing side areas is defined by a static bearing surface.

29. The extrusion device according to any of claims 20 to 28, wherein said topographic pattern comprises at least one protrusion, said protrusion being configured to form a separation notch in the extruded product and/or a significant local reduction of the thickness of the extruded product.

30. The extrusion device according to claim 29, wherein the significant reduction of the thickness of the extruded product def1nes a removable portion of the extruded product.

31. The extrusion device according to claim 29 or 30, wherein the at least one protrusion extends across the entire width of the first and/or second rotating die, or across a part of the width of the first and/or second rotating die.

32. The extrusion device according to any of claims 29 to 31, wherein said protrusion extends in a linear or curved manner across the width of the rotating die.

33. The extrusion device according to any of the preceding claims, further comprising an inlet configured to add a further material to the product material.

34. The extrusion device according to claim 33, wherein the inlet for adding a further material is arranged upstream, at, or downstream the first and second dies.

35. The extrusion device according to claim 33 or 34, wherein the inlet is configured to add a further material being a liquid or a solid material in the form of powder or particles.

36. The extrusion device according to any of claims 18 to 35, further comprising an adjustment mechanism configured to adjust the position of the first and/or second die thereby adjusting the dimensions of the channel.

37. The extrusion device according to any of claims 18 to 36, further comprising at least one die core in said channel, said die core forming a hollow portion of said extruded product.

38. An extrusion method, comprising: forming material by pressing or pulling a product material through a channel of an extrusion die, said channel being at least partly defined by the lateral surface area of at least a first rotating die and a second die arranged opposite the ﬁrst rotating die, and providing an upper side of the product material with an upper depression pattem being defined by the first rotating die, providing a bottom side of the product material with a bottom depression pattem being defined by the second die, said bottom depression pattern being provided simultaneously with the first depression pattern, wherein the upper depression pattem comprises at least one upper depression extending at least partly in a longitudinal direction of the extruded product, and the bottom depression pattern comprises at least one bottom depression extending at least partly in the longitudinal direction of the extruded product, wherein the extruded product further comprises at least one overlap area at Which the upper depression at least partly overlaps the bottom depression.