DE102024121178A1 - Method and molding tool for introducing at least one opening into a molded body made of a fibrous material and molded body - Google Patents

Abstract

A method for introducing at least one opening into a molded body made of a fibrous material, a molding tool for introducing at least one opening with a non-linear profile into a molded body made of a fibrous material, and a molded body made of fibrous material, comprising at least one surface section, wherein the at least one surface section has at least one opening with a non-linear profile, are described.

Description

Technical field

A method for introducing at least one opening into a molded body made of a fibrous material, a molding tool for introducing at least one opening with a non-linear profile into a molded body made of a fibrous material, and a molded body made of fibrous material, comprising at least one surface section, wherein the at least one surface section has at least one opening with a non-linear profile, are described.

background

Fibrous materials are increasingly used to manufacture packaging for food (e.g., trays, capsules, boxes, etc.) and consumer goods (e.g., electronic devices, etc.), as well as beverage containers. These fibrous materials can contain natural fibers, which are obtained, for example, from renewable resources or recycled paper. The natural fibers can be mixed with water and, if necessary, other additives such as starch in a pulp and then shaped. Additives can also affect the color, barrier properties, and mechanical properties. A pulp can contain, for example, 0.1 to 10% by weight of natural fibers. The proportion of natural fibers can vary depending on the manufacturing process used for the packaging and the product characteristics of the product being manufactured. Fibers, such as natural fibers, can also be introduced into molds in a dry state and processed or shaped within them. Alternatively, such fibers can be processed as raw materials for subsequent shaping. Starting materials for further processing can be, for example, so-called webs or sheets, such as airlaid, fluff pulp, paper, etc., as well as multi-layer arrangements of the aforementioned materials, made from a fibrous material, which are then formed in a mold.

Manufacturing processes for products or molded parts made from a fiber-containing material include a wet process, in which the molded parts are pressed from fibers that are drawn from an aqueous suspension and compressed into finished parts in one or more process steps under heat and pressure. Another manufacturing process is a so-called dry process, in which a relatively loose fiber composite (e.g., airlaid) with low moisture content is compressed into finished parts under high pressure and heat.

Fibrous products and molded parts often require openings in a section of their surface to allow liquid to enter an interior (e.g., coffee capsules) or to accommodate a straw or similar item (e.g., lids for beverage containers). Previously, such openings were created by punching holes. This process generates waste that must be removed from the die. Furthermore, these openings tend to fray, which can lead to further tearing and the release of fibrous material that can, for example, contaminate a beverage.

Task

The task is therefore to provide a solution that overcomes the disadvantages of the prior art and provides a solution for openings in molded parts made of a fibrous material that can be produced without waste, do not tend to tear or fray, and are easy to manufacture, with significantly reduced requirements for the manufacturing process and tooling.

Solution

• - Bereitstellen eines Formkörpers aus einem faserhaltigen Material, der mindestens einen Flächenabschnitt aufweist,
• - vollständiges Durchtrennen mindestens eines Bereichs des mindestens einen Flächenabschnitts zum Einbringen mindestens einer Öffnung,

wobei die mindestens eine Öffnung einen nicht linearen Verlauf aufweist.The aforementioned problem is solved by a method for introducing at least one opening into a molded body made of a fibrous material, wherein the method comprises the following steps:

• - Providing a shaped body made of a fibrous material, which has at least one surface section,
• - complete severing of at least one area of the at least one surface section to create at least one opening,

where at least one opening has a non-linear profile.

The non-linear shape of the opening allows for a relatively large opening cross-section without producing waste. This means that no material is punched out; instead, the non-linear shape of the opening allows a section of material surrounding it to be bent over, for example, when a straw is inserted or a liquid (e.g., hot water) comes into contact with the area containing the opening at high pressure.

In the case of molded bodies designed as coffee capsules, the formation of at least An opening with a non-linear profile provides a deflection surface through the material section surrounded by the at least one opening. This deflection surface can serve to divert incoming water, ensuring, for example, that the entire interior of a coffee capsule is thoroughly traversed. Furthermore, it is possible to create a filter. In other embodiments, the flow of coffee from a coffee capsule can also be controlled.

By creating openings with a non-linear profile, coffee develops a rich foam ("crema") and a particularly good coffee aroma. Previously, conventional coffee capsule designs required inserts that redirected the incoming water to achieve the desired coffee characteristics. The described design of openings with a non-linear profile eliminates the need for such inserts.

A non-linear curve can, for example, be curved or kinked. For instance, a curve can describe a segment of a circular arc.

In further embodiments, the creation of the at least one opening can be achieved by gradually plunging a cutting tool, with the opening being progressively enlarged as the cutting tool enters the material. This results in a clean cut compared to a sudden punching action, which offers the advantage of a defined cut edge in the fibrous material. This, in particular, prevents tearing or fraying. Furthermore, this method establishes a preferred direction for the material section that can be bent. For example, after the opening is created, the material section can be slightly deflected and inclined relative to the surface section. The preferred direction is the direction in which the material section can be bent. Bending in the opposite direction prevents the material section from being bent, or it will abut the edges of the at least one opening.

In further versions, several openings can be created simultaneously, with the respective openings being created by an increasing immersion of the cutting tool.

In further embodiments, to create a perforable weak point, the previously completely severed area with the opening can be pressed together in a subsequent step. This presses the fibrous material in the severed area against itself, creating a connection in that area that is weaker than the connection of the fibrous material in the remaining area of the surface section. This connection can then be broken, for example, by inserting a straw or applying hot water at a relatively high pressure (e.g., between 3 and 20 bar) to the opening. The pressing provides sufficient stability before the penetration, preventing, for example, the escape of coffee grounds.

A flap-like design of the bendable material section also prevents coffee powder and hot water from escaping in the opposite direction.

In further versions, at least one area and/or at least one surface section can be laminated or, for example, laminated after pressing to create a breakable or punctureable weak point in order to provide an additional coating for a barrier, etc.

In this process, the fibrous material on the opposing surfaces at the separation point (e.g., cut surfaces) of at least one area is pressed together after being completely cut through. This creates a force-fit connection between the surfaces at the separation point, forming the penetrable weak point. A penetrable interface can be designed to be punctured, allowing, for example, piercing with a straw or high-pressure water. Pressing the previously completely cut area together creates a weak point that is sufficiently strong to prevent unwanted penetration by substances (e.g., coffee grounds) and can be easily broken or punctured without damaging the surface area surrounding the weak point. A material-bonded connection between the fibers of the fibrous material in the separated areas does not exist in the fully formed weak point after pressing.

In other versions, the molded body can consist solely of the fiber-containing material and does not necessarily have to have lamination, etc.

Compared to known designs, creating vulnerabilities is easy to implement and allows for the provision of a wide variety of Molded parts with identical properties in the area of the weak point. In particular, the weak points of all molded parts exhibit the same behavior when broken or punctured and do not damage the surface area surrounding the at least one weak point. Cutting through the at least one weak point and subsequently pressing the at least one weak point together can be easily implemented using process engineering.

In further embodiments, the layer thickness of the fiber-containing material can be reduced in at least one area. This reduction in layer thickness can occur during pressing, thereby increasing the force on the opposing surfaces at the interface. A suitable pressing tool with a sufficiently large pressing surface can ensure that the fiber-containing material does not shift during pressing. This means that the orientation and shape of the surface section can be maintained even during pressing. Additionally, the layer thickness of a section adjacent to the at least one area can also be reduced.

In further details, pressing does not create a material-bonded connection between the fibers of the fiber-containing material in at least one area.

In further embodiments, the pressing process can be carried out at a temperature in the range of 1 to 250 °C. Preferably, the pressing process can be carried out from approximately room temperature, i.e., 20 °C.

In further versions, the pressing can take place at a pressure in the range of 1 to 250 N/mm ² , in particular in the range of 100 to 200 N/mm ² .

In further embodiments, the provision of the molded part can additionally include a manufacturing step in which fiber-containing material is formed into a molded part. Such a manufacturing step precedes the formation of the molded part and can, for example, be carried out in a single system. Alternatively, the molded part can be produced beforehand and then fed to a device for creating weak points. The manufacturing step can, for example, involve forming parts from a pulp or from a relatively dry material (e.g., airlaid, etc.).

In further embodiments, the at least one area can be moistened after being cut and before being pressed together. This moistening can positively influence the subsequent pressing process, resulting, for example, in stronger compression and thus greater pressure on the separated surfaces (a stronger force-fit connection), since moister material – depending on the material type and processing – can be pressed together more easily. No material bond is formed in this process, so the advantage of the force-fit connection at the weak point is retained.

In further embodiments, the cutting and/or pressing of at least one area can take place on opposite sides of at least one surface section. A reduction in layer thickness on both sides can also occur.

The aforementioned problem is also solved by a forming tool for introducing at least one opening with a non-linear profile into a molded body made of a fibrous material, comprising at least one cutting tool which has at least one cutting element which has a cutting edge which is non-linear in accordance with the non-linear profile of the at least one opening, wherein the cutting edge is not parallel to an area of a surface section of a molded body into which the at least one opening is to be introduced, so that during the introduction of the at least one opening, it is increasingly possible to cut through the fibrous material over a length of the at least one opening.

By progressively creating at least one opening with a non-linear profile, a defined cutting edge is generated, and a filter/valve function is provided, since the material section surrounded by the cut area can only be moved in one direction. This design of the cutting element also allows for a reduction in cutting forces, making the fibrous material less prone to uncontrolled tearing or even preventing it from tearing at all. A pulling cut therefore enables improved opening formation and also has a positive effect on the opening creation method described above, as higher tolerances can be accepted. Furthermore, lower cutting forces are advantageous with a pulling cut because the material is subjected to less stress.

In further embodiments, the at least one cutting element can be displaced relative to the surface section to create the at least one opening.

In other versions, the cutting edge can have a varying course in the direction of movement.

In further embodiments, at least one cutting element can be cylindrical and have at least two cutting areas which have a smaller distance to the surface section compared to at least one further cutting area.

In other versions, the forming tool can have several cutting elements.

The aforementioned problem is further solved by a shaped body made of fibrous material, comprising at least one surface section, wherein the at least one surface section has at least one opening with a non-linear course, wherein a material section surrounding the at least one opening is spring-loaded by the non-linear course of the at least one opening.

The spring-loaded design of the material section can be implemented as described above, allowing deflection of the material section in only one direction. This enables various functions (filter, valve) to be achieved simply by forming at least one opening, eliminating the need for additional elements and simplifying the provision of these functions.

Further features, designs and advantages will become apparent from the following presentation of exemplary embodiments with reference to the figures.

Brief description of the characters

• 1 eine schematische Darstellung eines Flächenabschnitts eines Formteils während des Einbringens einer Öffnung in einem Formwerkzeug;
• 2 eine weitere schematische Darstellung des Flächenabschnitts von 1 während des Einbringens einer Öffnung in einem Formwerkzeug;
• 3 eine schematische Darstellung eines Schneidelements eines Formwerkzeugs;
• 4 schematische Darstellungen von Öffnungen mit einem nicht linearen Verlauf;
• 5 eine schematische Darstellung der Ausbildung von Öffnungen im Schnitt; und
• 6 eine schematische Darstellung eines Flächenabschnitts eines Formkörpers beim Verpressen einer Öffnung.

The drawings show:

• 1 a schematic representation of a surface section of a molded part during the creation of an opening in a molding tool;
• 2 another schematic representation of the area section of 1 during the creation of an opening in a mold;
• 3 a schematic representation of a cutting element of a forming tool;
• 4 schematic representations of openings with a non-linear profile;
• 5 a schematic representation of the formation of openings in cross-section; and
• 6 A schematic representation of a surface section of a molded body during the pressing of an opening.

Detailed description of implementation examples

The following are exemplary embodiments of the technical teaching described herein, with reference to the figures. The same reference numerals are used in the figure descriptions for identical components, parts, and processes. Components, parts, and processes that are immaterial to the technical teaching disclosed herein or that are obvious to a person skilled in the art are not explicitly shown. Features given in the singular are also included in the plural unless explicitly stated otherwise. This applies in particular to terms such as "a" or "an".

1 Figure 1 shows a schematic representation of a surface section 10 of a molded part during the creation of an opening 16 in a mold 30. Molded parts made of a fibrous material can be, in particular, three-dimensional molded parts used for receiving, storing, and/or dispensing liquids, etc. For example, a three-dimensional molded part made of a fibrous material can be a coffee capsule. Such coffee capsules have a receiving chamber that is filled with coffee powder and is sealed by a side wall, a bottom surface, and a further cover, the latter usually being applied after filling. All components can consist of a fibrous material, and the components may have been produced, for example, in a wet or dry molding process as mentioned above. In further embodiments, the outer and/or inner surface that is in direct contact with a contents (e.g., coffee powder) can have a barrier. For example, the surfaces can be laminated.

Coffee capsules, for example, have a piercing area to allow the introduction of hot water at a pressure of approximately 10-20 bar. This piercing area may contain several small openings. These openings can be created, for example, by the piercing mechanism of a coffee machine when it closes in a brewing chamber. Furthermore, coffee capsules have an area on the opposite side through which the liquid introduced into the capsule, as coffee, is released. This area also features small openings. The design of these release openings is crucial for the quality and consistency of the coffee.

With coffee capsules made of fibrous material, the openings created by the coffee machine's piercing mechanism can be very imprecise. This means that the openings tear easily and lack a clear edge, making it difficult to control the flow of coffee. As a result, the openings vary in size and can enlarge uncontrollably. Therefore, especially for coffee capsules made of fibrous material, special additional elements, such as plastic mesh or similar, are necessary to prevent the openings from being damaged or to keep the opening size (dimensions and cross-section) within a predefined range. Furthermore, such meshes can help direct the flow of coffee and thus create foaming. The same principle applies to the design of the openings in coffee capsules.

In further embodiments, capsules or the like made of a fibrous material may require openings to provide pressure equalization. Furthermore, capsules or the like made of a fibrous material may require openings 16 that have a filtering effect, retaining substances (e.g., coffee grounds).

To provide openings 16 that can be produced without waste and that do not tear or become damaged when media (e.g., water, coffee, etc.) or objects (e.g., drinking straws) penetrate or flow through, it is proposed to design the openings 16 with a non-linear profile. This makes it possible to create an opening 16 with a relatively large opening width without requiring punching and thus generating no waste. Furthermore, a portion of the fibrous material can serve as a valve for venting and as a deflector, for which purpose a section of material can be designed as a flap 14. Such a flap 14 can be moved in only one direction and, when moved in the opposite direction, rests against the edge of the opening 16, thereby blocking it. This can serve to define a specific flow direction for liquids and gases.

In 1 Figure 1 schematically shows a part of a forming tool 30, which has an upper tool part with at least one cutting element 32 and a lower part 38. The lower part 38 has an opening 39, which is designed such that the cutting element 32 can immerse itself in it, as shown in Figure 2. 2 shown.

To create openings 16, the surface section 10 of a molded part is moved between the upper tool part with the cutting element 32 and the lower part 38 such that a region 12 of the surface section 10, into which the at least one opening 16 is to be created, is aligned with the cutting element 32 and the opening 39. The surface section 10 can be fixed relative to the lower part 38 by means of a holding frame 36. This prevents the fibrous material from yielding and the surface section 10 from being displaced or undergoing a compensatory movement. In further embodiments, a holding frame 36 or a similar device can be directly connected or coupled to the upper tool part, so that when the mold 30 is closed to create the opening 16, the surface section 10 is automatically held in place.

Subsequently, as indicated by the arrow, the cutting element 32 is moved relative to the opening 39, whereby the cutting element 32 dips into the fibrous material and thereby creates an opening 16 in the area 12. 2 Another schematic representation shows area section 10 of 1 during the creation of an opening 16.

In the exemplary embodiment of the 1 and 2 A cutting element 32 is shown, whose cutting edge 34 describes a circle parallel to the surface section 10 and has two maxima in the closing direction of the forming tool 30. That is, the cutting edge 34 of the cutting element 32 has a varying profile in the closing direction. The cutting element 32 is designed similarly to a punch of a hole punch. Unlike punching with such punches, the cutting element 32 in the illustrated embodiment is not completely immersed in the fibrous material, so that the fibrous material is only cut in the region of the maxima, i.e., not over the entire circumference of the cutting edge 34. Furthermore, the cutting occurs in the embodiment of 1 and 2 The process does not occur abruptly, but rather gradually as the cutting element 32 is moved further. The fibrous material is not generated simultaneously along the entire length of the at least one opening 16. This also results in a shaping process in area 12, forming flaps 14 that are inclined in the closing direction of the forming tool 30.

The exemplary embodiment of 1 and 2 The cutting element 32 creates two openings 16 during cutting, the course of which each describes a circular arc segment.

3 Figure 1 shows a schematic representation of a cutting element 32 of the forming tool 30, as in the design of 1 and 2 shown. The cutting edge 34 of the cutting element 32 has a The cutting edge 34 exhibits a varying profile in the closing direction of the forming tool 30. The profile of the cutting edge 34 allows for progressive shearing of the fibrous material as the forming tool 30 closes or as the cutting element 32 moves. This results in a pulling cut, in which the cutting forces are reduced, preventing the fibrous material from tearing in the material or in the opening 16 at the cutting edge. Furthermore, lower cutting forces also result in lower stress in the material, which is essentially held in place, for example, by a retaining frame 36.

The cutting edge 34 can be very thin. For example, the cutting edge 34 can have a width of approximately 0.5 to 3 mm, with the tip ideally being almost 0 mm wide. In other versions, cutting edges 34 can have a point or cutting angle of approximately 30–60°. Cutting edges 34 can be designed differently depending on the requirements. For example, cutting edges 34 can be designed very differently in detail and differ, for example, in terms of the grind (e.g., single-bevel ground, double-bevel ground, four-bevel ground, etc.). Furthermore, cutting edges 34 with a rounded tip can also be used in other versions.

In further embodiments, a forming tool 30 can have several cutting elements 32, so that a large number of openings 16 can be produced simultaneously in a surface section 10 and/or in a large number of shaped bodies.

4 shows schematic representations of openings 16 with a non-linear profile. Thus, the cutting element 32 can be used to... 1 , 2 until 3 e.g. two arc-shaped openings 16 are created ( 4a) In further embodiments, a cutting element 32 can also have four maxima, so that four arc-shaped openings 16 can be produced, as in 4b) shown.

4c ) shows a further development of a pair of openings 16, which are shaped like clamps. 4d ) shows a version with three clamp-like openings arranged one behind the other 16. 4e) shows a version with three semicircular openings arranged one behind the other 16.

In further embodiments, additional non-linear openings 16 can also be introduced into a surface section 10, the course of which is non-linear and differs from the embodiments shown.

5 Figure 1 shows a schematic cross-sectional representation of the formation of openings 16, with two flaps 14 formed. As indicated by the arrows, the flow or penetration of liquids or air can only occur in one direction. The orientation of the flaps 14 is influenced by the manufacturing process, with the cutting direction during the creation of the openings 16 determining the orientation of the flaps 14. Displacement of the flaps 14 from the plane of the surface section 10 in the opposite direction is prevented, as the flaps 14 cannot cross the opening or the cut area of the fiber-containing material.

6 Figure 1 shows a schematic representation of a surface section 10 of a molded body during the pressing process to create puncture-proof weak points 18. For this purpose, the surface section 10 with the openings 16 is placed in a stamping tool 40, which in the illustrated embodiment has two punches 42. The area 12 can be pressed closed after the openings 16 have been created using the two punches 42, so that the flap-like material sections (flaps 14) close the openings 16 again. However, the connection created by the pressing process is not very strong, so that easy opening is possible.

In the openings 16, a surface section 10 after separation at a separation point (opening 16) has opposite surfaces that are completely separated from each other and have no material bond.

During pressing, the embossing dies 42 are pressed against the area 12 until a force-fit connection is formed between the surfaces in the separation point/opening 16, thereby closing a gap. In the illustrated embodiment, the embossing area, i.e., the area of the fiber-containing material being pressed, extends beyond the openings 16. This ensures that any material accumulation in the area of the openings 16 is also pressed, so that no accumulation remains after pressing due to the separation or cut.

In further variations, the embossing surface can be provided with a pattern or the like, so that an embossing with a corresponding pattern can be created on the surface of the pressed area. For this purpose, the embossing surface can, for example, have raised areas and/or indentations in the form of parallel and/or intersecting grooves, lines, etc. Furthermore, such raised areas and/or indentations can be curved along the embossing surface.

After pressing, the weak point 18 can be compressed relative to the rest of the surface area 10 and have a small layer thickness. Any protrusions or material accumulations are also flattened by a cut. Furthermore, the compression of the material presses the surfaces in the openings 16 against each other, creating a force-fit connection between the surfaces. To achieve a force-fit connection and prevent compensatory movement of the fiber-containing material, the embossed surface or area is preferably dimensioned accordingly, i.e., made wide. The force-fit connection provides a sealing solution for the weak point 18, while at the same time allowing for easy penetration or puncturing because there is no material bond. Moreover, puncturing (e.g., with a straw or similar object) does not cause uncontrolled tearing or other damage to the surface area 10 because a predetermined breaking point is present and the weak point 18 already has a completely separated area.

The introduction of openings 16 into a surface section 10 of a molded body made of a fibrous material can involve several process steps.

Initially, a molded body 10 can be provided, whereby the provision can comprise a molding step. This can be done either by molding from a relatively dry fiber material (dry forming) or by molding from an aqueous fiber suspension (pulp) (wet forming). In a so-called wet process, preforms made of a fiber-containing material can first be provided, which are then compressed under thermal influence. The preforms can be provided by drawing fibers from an aqueous solution (pulp) and forming three-dimensional preforms that essentially already have the shape of the products to be manufactured. Additionally, additives and components, such as starch, chemical additives, wax, etc., can be added to a pulp to influence the properties of the products to be manufactured (e.g., barrier properties) and their processability. The fibers can be, for example, natural fibers such as cellulose fibers, or fibers from a fibrous source material (e.g., recycled paper). Since a fibrous pulp containing natural fibers can be used as the starting material for the molded parts, the manufactured parts can themselves be reused as raw material for the production of molded parts or other products, or composted, because they are generally completely decomposable and do not contain any harmful or environmentally hazardous substances. The preforms can undergo a pre-pressing step in further processes. Subsequently, the preforms are pressed into three-dimensional molded parts in a hot-pressing device under pressure and heat. Furthermore, the molded parts can be formed from a loose cellulose web (airlaid) or paper.

This is followed by the creation of at least one opening 16 or cutting in an area 12 of a surface section 10 of a molded part made of fibrous material, whereby the fibrous material in this area is completely cut through. The cutting can be carried out by relative displacement of two tool parts, e.g. cutting element 32 and lower part 38.

Subsequently, the previously created opening 16 can be pressed closed with another tool component, e.g., a punch 42. This pressing can be carried out in the same tool or in a separate tool. Furthermore, in other embodiments, the embossing surface of at least one punch 42 can be temperature-controlled to improve the compression of the fiber-containing material in area 12 with the opening 16. Preferably, such pressing is carried out at temperatures of 50 to 150 °C. In other embodiments, pressing can be performed from only one side using a punch 42 and a counter-position.

In further embodiments, after creating an opening 16 and before pressing, the area 12 can be optionally moistened, whereby the area 12 can be dried during pressing at correspondingly higher temperatures (e.g., between 90 and 150 °C). No material bond is formed, so the advantage of the force-fit connection at a weak point 18 is retained.

The diameter or cross-section of openings 16, i.e. the distance between the ends of the openings 16 or the length of the course of the openings 16, can be, for example, between 2 and 10 mm.

Reference symbol list

10

Area section

12

Area

14

Flap (Material section)

16

opening

18

Weak point

30

Forming tool

32

Cutting element

34

Cutting edge (WZ)

36

Mounting frame

38

lower part

39

opening

40

embossing tool

42

Rubber stamp

Claims (10)

A method for introducing at least one opening into a molded body made of a fibrous material, comprising the following steps: - providing a molded body made of a fibrous material having at least one surface section, - completely cutting through at least one area of the at least one surface section to introduce at least one opening, wherein the at least one opening has a non-linear shape. Procedure according to Claim 1 , wherein the creation of the at least one opening is achieved by an increasing immersion of a cutting tool, the opening being created increasingly as the cutting tool is immersed. Procedure according to Claim 1 or 2 , whereby several openings are created simultaneously, with the respective openings being created by an increasing immersion of the cutting tool. Procedure according to one of the Claims 1 until 3 , wherein, in order to form a perforable weak point, the previously completely severed at least one area is pressed together with the at least one opening in a subsequent step, wherein the fibrous material in the at least one severed area is pressed against each other and thereby a connection is created in the at least one area which is weaker than the connection of the fibrous material in the remaining area of the at least one surface section. A forming tool for introducing at least one opening with a non-linear profile into a molded body made of a fibrous material, comprising at least one cutting tool which has at least one cutting element having a non-linear cutting edge corresponding to the non-linear profile of the at least one opening, wherein the cutting edge is not parallel to an area of a surface section of a molded body into which the at least one opening is to be introduced, so that during the introduction of the at least one opening, it is increasingly possible to cut through the fibrous material over a length of the at least one opening. Forming tool according to Claim 5 , wherein the at least one cutting element is movable relative to the surface section to create the at least one opening. Forming tool according to Claim 6 , whereby the cutting edge has a varying profile in the direction of movement. Forming tool according to one of the Claims 5 until 7 , wherein the at least one cutting element is cylindrical and has at least two cutting areas which are at a smaller distance to the surface section compared to at least one further cutting area. Forming tool according to Claim 8 , comprising several cutting elements. Molded body made of fibrous material, comprising at least one surface section, wherein the at least one surface section has at least one opening with a non-linear course, wherein a material section surrounding the at least one opening is spring-loaded by the non-linear course of the at least one opening.