Components with a common recess for form-fittingly receiving a fitting with a moveable undercut

Abstract

The invention relates to a connection structure (100), which is formed from at least two components (102, 104), wherein in the at least two components (102, 104) a common recess (106) is formed for form-fittingly receiving a fitting (108), wherein the recess (106) has a first hollow wing portion (112) extending from a central hollow portion (110) of the recess (106) along a first direction (182), a second hollow wing portion (114) extending from the central hollow portion (110) of the recess (106) along another, for example opposite, second direction (184), a first hollow undercut (116) on a free first end of the central hollow portion (110), the first hollow wing portion (112) and / or the second hollow wing portion (114), and a second hollow undercut (118), spaced apart from the first hollow undercut (116), on a free second end, opposite the first end, of the central hollow portion (110), the first hollow wing portion (112) and / or the second hollow wing portion (114).

Description

[0001] Components with a common recess for the positive reception of a fitting with a movable undercut

[0002] The invention relates to a connecting structure, a fitting, an arrangement, a processing tool and a method.

[0003] Fittings are used to connect components. Fittings are typically made of metal and can be attached to wooden components, for example, with nails. Furniture, doors, windows, etc., can be fitted with such fittings. Plastic fittings are also commonly used in furniture construction.

[0004] WO 2008 / 135250 A2 discloses a connecting means for connecting a first component and a second component, in particular for connecting furniture or machine parts, comprising a first connecting element arranged on the first component when the components are connected, and a second connecting element arranged on the second component when the components are connected. At least one of the connecting elements is provided with at least one non-self-tapping retaining projection having a curved support surface that is circular in cross-section, wherein the retaining projection is insertable into a groove provided on one of the components with a curved undercut surface that is circular in cross-section.

[0005] Other connection systems are disclosed in EP 1,602,428 A1, EP 0,515,916 A2, EP 1,602,839 B1 and WO 2005 / 118190 A1.

[0006] Also well-known are the ZYKON undercut anchors FZA from Fischer. An undercut hole is created using a special FZUB drill bit. The undercut anchor is installed using pre-inserted and push-through installation methods. Using the FZE Plus setting tool, the expansion sleeve is pushed over the cone and fills the undercut hole with a positive fit.

[0007] Another well-known anchor is the HSC-I undercut anchor from Hilti. This requires only a simple cylindrical hole; no separate undercut is required. A self-undercutting feature allows installation without a separate undercutting tool and without any special handling.

[0008] The invention is based on the object of enabling reliable assembly of components to one another.

[0009] This object is achieved by the subject matter according to the independent patent claims. Further developments of the invention arise from the dependent claims.

[0010] According to an exemplary embodiment of the invention, a connecting structure is created which is formed from at least two components, wherein a recess for positively receiving a fitting (for example a fitting with the features described below) is formed in the at least two components, wherein the recess has a first hollow wing section extending from a central hollow section of the recess along a first direction, a second hollow wing section extending from the central hollow section of the recess along another, for example opposite, second direction, a first hollow undercut at a free first end of the central hollow section, the first hollow wing section and / or the second hollow wing section,and a second hollow undercut arranged at a distance from the first hollow undercut at a free second end of the central hollow section, the first hollow wing section and / or the second hollow wing section opposite the first end.

[0011] According to another exemplary embodiment of the invention, a fitting is provided for positively receiving in a recess of a connecting structure (for example, a connecting structure with the features described above), which is formed from at least two components, wherein the recess is formed jointly in the at least two components, wherein the fitting has a first wing section extending from a central section along a first direction, a second wing section extending from the central section along another, for example opposite, second direction, a first undercut section at a free first end of the central section, the first wing section and / or the second wing section, a second undercut section at a free second end of the central section, the first wing section and / or the second wing section opposite the first end,and an extension and / or retraction mechanism configured to selectively extend and / or selectively retract the first undercut portion and / or the second undercut portion (for example, transversely to the first direction and transversely to the second direction).

[0012] According to yet another exemplary embodiment of the invention, an arrangement is provided which comprises a connecting structure having the features described above and a fitting having the features described above, which is mounted or mountable in a form-fitting manner in the recess of the connecting structure.

[0013] According to yet another exemplary embodiment of the invention, a machining tool is provided for forming a recess in a connecting structure which is formed from at least two components, wherein the recess for positively receiving a fitting is formed in the at least two components together, wherein the machining tool is designed to have in the connecting structure a first hollow wing section extending from a central hollow section of the recess along a first direction, a second hollow wing section extending from the central hollow section of the recess along another, for example opposite, second direction, a first hollow undercut at a free first end of the central hollow section, the first hollow wing section and / or the second hollow wing section,and to form a second hollow undercut arranged at a distance from the first hollow undercut at a free second end of the central hollow section, the first hollow wing section and / or the second hollow wing section opposite the first end.

[0014] According to yet another exemplary embodiment of the invention, a method is provided for the positive connection of at least two components of a connecting structure having the features described above by means of a fitting having the features described above, wherein the method comprises forming the recess in the at least two components of the connecting structure, inserting the fitting into the recess with the first undercut section and / or with the second undercut section retracted, and subsequently actuating the extension and / or retraction mechanism for extending the first undercut section into the first hollow undercut and / or the second undercut section into the second hollow undercut, in order to thereby fasten the fitting in a positive fit in the recess while positively connecting the at least two components.In the context of this application, the term "fitting" can be understood in particular as a component or assembly used to fasten components, in particular to provide a connecting function and / or a movement function. In particular, such fittings can be used for interior fittings (e.g., for doors) and as furniture fittings (e.g., for cabinets). Fittings can be an integral component or an assembly constructed from several separate sub-components.

[0015] In the context of the present application, the term "connecting structure" can be understood as an arrangement of several components between which a recess is formed. Such a connecting structure can represent a structure to be connected, the components of which can be connected to one another by means of at least one fitting. Said recess of the connecting structure can be formed partially by one component and partially by another component. The recess can be accessible from outside the connecting structure, for example, for manual operation by a user or for operation by means of an operating tool. It is also possible for the recess to be inaccessible from the outside.

[0016] In the context of the present application, the term "positively locking receiving of a fitting in a recess of a connecting structure" can be understood in particular to mean that the shapes of the recess and the fitting are adapted to one another in such a way that at least one section of the fitting prevents the components of the connecting structure from being separated.

[0017] In the context of the present application, the term "central hollow section" can be understood as a central section of a recess, from which further hollow structures of the recess extend along at least two directions (which may, for example, be oriented opposite to each other).

[0018] In the context of the present application, the term "hollow wing section" can be understood as a respective hollow structure of the recess, which extends from a central hollow section to a respective lateral end of the recess. Opposing hollow wing sections can be hollow structures in the components that extend along opposite directions. The latter can, for example, enclose a 180° angle with each other or another obtuse angle deviating therefrom.

[0019] In the context of the present application, the term "hollow undercut" can be understood as a hollow structure of the recess that is undercut relative to an associated hollow wing section and / or the central hollow section. For example, a hollow undercut can extend from a free end of the respective hollow wing section and / or the central hollow section transversely or even perpendicularly to the associated hollow wing section and / or the central hollow section.

[0020] In the context of the present application, the term "central section" of a fitting can be understood as a solid-state structure located in a central section of the fitting. Wing sections of the fitting can extend from such a central section, for example, integrally with the central section or as separate bodies. In the context of the present application, the term "wing section" can be understood as a solid-state structure of the fitting that extends from a central section of the fitting to one end of the fitting. In particular, two wing sections can extend from the central section along different directions. The different directions can be opposite to one another and therefore enclose an obtuse angle or even an angle of 180°.

[0021] In the context of the present application, the term "undercut section" can be understood in particular as a solid-state structure which can extend transversely or even perpendicularly from an associated wing section and / or from the central section in order to be undercut relative to the associated wing section and / or the central section. An undercut section can in particular be designed to be converted by appropriate actuation (in particular by appropriate application of force) between an undercut configuration with respect to the associated wing section and / or the central section and a non-undercut configuration.An undercut section can also be configured to be converted, by appropriate actuation (in particular by applying appropriate force), between a more strongly undercut configuration relative to the associated wing section and / or the central section and a less strongly undercut configuration. For example, the wing section and / or the central section and the undercut can be formed integrally or as separate structures.

[0022] In the context of the present application, the term "extension and / or retraction mechanism" can be understood in particular as a component, a body or a plurality of interacting components or bodies which can be actuated (for example by means of an actuating tool or by a user) in such a way that at least one undercut section selectively extends into an undercut or more strongly undercut extension position or retracts into a non-undercut or less strongly undercut retraction position. In this way, the fitting can be positively locked in a recess of a connecting structure when the extension and / or retraction mechanism is extended. The extension and / or retraction mechanism can in particular be designed to reversibly extend or retract the at least one undercut section.

[0023] According to an exemplary embodiment, a connecting structure and an associated fitting are provided, with which a positive connection of components of the connecting structure can be achieved in a simple, effective and reliable manner by means of the fitting. For this purpose, the fitting and the recess of the connecting structure can be shaped substantially inversely to one another in order to enable the positive connection. Furthermore, the recess has a hollow undercut and the fitting is equipped with corresponding undercut sections which can be extended by means of an extension and / or retraction mechanism to form a positive connection. Furthermore, the undercut sections can be selectively retracted, for example in preparation for a connecting process or for the reversible release of a positive connection. By the undercut sections being provided on free ends of the wing sections orof the central section, these can be brought into particularly effective engagement with the correspondingly positioned hollow undercuts of the recess in the components when the extension and / or retraction mechanism is extended. This not only ensures a particularly reliable, positive-locking connection, but also high stability and can also enable rapid formation or release of the connection. Further details of the connection structure, the fitting, the arrangement, the processing tool, and the method are described below.

[0024] According to one embodiment, the connecting structure is designed as a panel corner connecting structure. In particular, the connecting structure can be formed from the at least two components in order to positively connect two panel-shaped components to one another, wherein a part of the recess in a narrow side is formed by one panel-shaped component and another part of the recess in a main surface is formed by another panel-shaped component. As a result, an angular, in particular right-angled, connection between panel components can be achieved by means of the fitting and the connecting structure. More generally, however, the connecting structure can also have two differently shaped components or more than two components, for example three, four, or five components.

[0025] According to one embodiment, the central hollow section is formed as a cylinder section, a plate section, or a structure with two round end sections (in plan view) and two straight connecting lines connecting them. Thus, different shapes are possible as long as a central hollow section and two hollow wing sections are formed.

[0026] According to one embodiment, the at least two components comprise two panels. Connecting panels by means of a fitting to form a positive connection can be advantageously used, for example, in furniture construction.

[0027] According to one embodiment, the first hollow undercut and / or the second hollow undercut is undercut along its entire circumference relative to the central hollow section, the first hollow wing section, and the second hollow wing section. Such a circumferential undercut can be formed particularly easily in terms of manufacturing technology, for example, using an end mill. At the same time, such an annular undercut allows for a reliable, positive connection with the associated undercut sections.

[0028] According to one embodiment, the first hollow undercut and / or the second hollow undercut has an outline defined (in plan view) by two semicircles and two linear connecting lines between the semicircles. Such a geometry is shown, for example, in Figure 1 and is easy to manufacture.

[0029] According to one embodiment, the at least two components comprise wood, in particular plywood and / or a wood fiber material. Thus, through the interaction of the connecting structure with the fitting, even relatively inexpensive wood fiber material components can be reliably connected to one another in a form-fitting manner. Alternatively, such a form-fitting connection is also possible with higher-quality plywood. According to a further alternative, the components can comprise or consist of solid wood.

[0030] According to one exemplary embodiment, a first component of the at least two components has a part of the central hollow section, a part of the first hollow wing section, a part of the second hollow wing section, and the entire first hollow undercut, whereas a second component of the at least two components has a different part of the central hollow section, a different part of the first hollow wing section, a different part of the second hollow wing section, and the entire second hollow undercut. In other words, the recess sections in the two components to be connected to one another can be formed symmetrically or correspondingly. However, it is possible for a partial hollow volume of the recess section in the first component to be different from a partial hollow volume of the recess section in the second component.In this way, different processing volumes or different material properties in the components can be taken into account.

[0031] According to one exemplary embodiment, at least one of the at least two components has an access hole opening into the recess for actuating, in particular by means of an actuating tool, an extension and / or retraction mechanism of the fitting when the fitting is inserted into the recess. Such an access hole can advantageously enable access to the fitting when the fitting is arranged inside the connecting structure, i.e., in its recess. A user can then extend the undercut sections through the access hole to activate the positive connection between the fitting and the connecting structure. In particular, it can be made possible for the actuating tool to actuate the extension and / or retraction mechanism of the fitting through the access hole to trigger extension or retraction.

[0032] According to one exemplary embodiment, the central hollow section, on the one hand, and the first hollow wing section and the second hollow wing section, on the other hand, have different maximum diameters transverse to the first direction and transverse to the second direction, viewed along an axial direction of the central hollow section. Figures 8 to 10 show different alternatives in this regard.

[0033] According to one embodiment, the central hollow section, the first hollow wing section, and the second hollow wing section are together rectangular in a viewing direction perpendicular to an axial direction of the central hollow section and perpendicular to the first direction and the second direction. This results in a high degree of stability of the connection without any mechanical weak points.

[0034] According to one embodiment, the first hollow undercut and the second hollow undercut are not connected to each other. In other words, there can be no direct physical contact between the first hollow undercut and the second hollow undercut. In this way, the two hollow undercuts can act in volume regions of the components that are arranged remotely from each other, which further increases the stability of the connection.

[0035] According to one embodiment, the first hollow undercut is annularly closed and / or the second hollow undercut is annularly closed. Such a configuration is easily manufactured, for example, using a milling tool and offers a high degree of design freedom with regard to the engagement of the undercut sections in the hollow undercuts.

[0036] According to one embodiment, the fitting can be designed to be handled in one piece. This means that a user can handle the entire fitting as a single piece throughout the entire assembly process and does not have to handle several separate components of the fitting separately (see, for example, Figures 2 and 3). This increases error robustness and allows even users without specialized knowledge to securely anchor the fitting in the connecting structure. In other embodiments, the fitting can also be designed in multiple pieces (see, for example, Figures 11 to 15).

[0037] According to one embodiment, the fitting is formed at least partially, in particular predominantly, and further in particular entirely, from biogenic material. Within the scope of this application, the term "biogenic material" can be understood in particular to mean material that is of biological or organic origin or originates from living organisms. In particular, biogenic materials include renewable raw materials. Within the scope of this application, the term "predominantly made of biogenic material" can be understood in particular to mean that biogenic material is the main component of the fitting. The weight proportion of the biogenic material in the fitting can therefore be more than 50%, in particular more than 70%, in each case based on the entire fitting. This allows the fitting to be manufactured sustainably without compromising the reliability of the connection.

[0038] According to one embodiment, the fitting is made predominantly or entirely of plant material. Plant material, especially wood, also exhibits sufficiently high strength to be used as the material for at least part of the fitting.

[0039] According to one embodiment, the fitting may comprise a binding agent, in particular an adhesive (e.g., glue), in addition to the biogenic material. This can improve the robustness of the fitting.

[0040] In particular, the biogenic material may comprise biogenic fibers, such as plant fibers (especially wood fibers). For example, the biogenic material of the fitting may comprise wood material, foliage, and / or natural polymers.

[0041] According to one embodiment, the central section, the first wing section, the second wing section, the first undercut section, and the second undercut section are made at least partially from biogenic material, in particular from plant material. In particular, all components of the fitting, with the exception of the extension and / or retraction mechanism, can be made from biogenic material. However, embodiments are also possible in which the extension and / or retraction mechanism is also made from biogenic, in particular plant, material.

[0042] According to one embodiment, the extending and / or retracting mechanism is made of metal, ceramic, and / or plastic. Such an embodiment is particularly advantageous when an extending and / or retracting mechanism is exposed to particularly harsh conditions during operation or is required to achieve a particularly strong connection force.

[0043] According to one embodiment, the extension and / or retraction mechanism is designed to selectively extend the first undercut section and the second undercut section in a first transverse direction and in a second transverse direction opposite to the first transverse direction, transverse to the first direction and transverse to the second direction. If a respective undercut section is extended transversely or even perpendicularly to the associated wing section from which the said undercut section extends, this undercut section can be retracted into an associated hollow undercut in the recess of the connecting structure according to the key-lock principle, thus forming the positive connection. If this occurs simultaneously for two undercut sections and two associated hollow undercuts in opposite directions, a double and therefore particularly reliable undercut connection can be realized.

[0044] According to one embodiment, the extension and / or retraction mechanism is configured to be actuated by a user or an actuating tool to selectively extend and / or retract the first undercut section and / or the second undercut section. For example, a drive may be provided on the extension and / or retraction mechanism for this purpose, which drive can be engaged by a corresponding actuating tool (e.g., an Allen key, a screwdriver, or a cordless screwdriver). By rotating, the extension and / or retraction mechanism can then be operated in a simple and reliable manner to extend or retract undercut sections.

[0045] According to one embodiment, the extension and / or retraction mechanism is configured to be actuated by rotating and / or sliding in order to selectively extend and / or retract the first undercut section and / or the second undercut section. A rotating or sliding movement is a movement that can be easily and intuitively performed by a user in order to transfer a fitting, and in particular its extension and / or retraction mechanism, between different operating states.

[0046] According to one embodiment, the extension and / or retraction mechanism is configured to be actuated to selectively extend the first undercut section and / or the second undercut section and thereby clamp it relative to at least one of the at least two components. If the fitting is clamped relative to the components of the connecting structure in the recess, a clamping force can further strengthen the attachment between the connecting structure and the fitting in addition to the positive fit.

[0047] According to one embodiment, the fitting comprises a first fitting component with a part of the central section, the first wing section, the second wing section, the first undercut section, and the second undercut section, and a second fitting component with another part of the central section, the first wing section, the second wing section, the first undercut section, and the second undercut section, wherein the extension and / or retraction mechanism forms a third fitting component that is at least partially arranged between the first fitting component and the second fitting component. For example, the first fitting component can be a plate-like structure and the second fitting component can be another plate-like structure, between which a third plate-like structure is arranged to form the extension and / or retraction mechanism.For example, the extension and / or retraction mechanism between the two fitting components can be rotated, thereby triggering the extension or retraction of the undercuts. This can be caused, for example, by a non-rotationally symmetrical or eccentric component of the plate-shaped extension and / or retraction mechanism, which exerts a stronger or lesser influence on the fitting components depending on the rotational position.

[0048] According to another exemplary embodiment, the fitting has a first fitting component with a part of the central section, the first wing section, the second wing section, the first undercut section and the second undercut section, and a second fitting component with another part of the central section, the first wing section, the second wing section, the first undercut section and the second undercut section, wherein the extension and / or retraction mechanism is formed as part of the first fitting component and / or the second fitting component. In such an alternative embodiment, the fitting components themselves can have an extension and / or retraction mechanism integrated therein. If, for example, two plate-shaped fitting components with a corresponding outer contour are rotated against one another, this can also result in an extension or retraction.Cause retraction of undercut sections provided on the fitting components.

[0049] According to one embodiment, the first undercut section and / or the second undercut section has expandable expansion elements by actuating the extension and / or retraction mechanism, which, when expanded, positively engage in a first hollow undercut and / or a second hollow undercut of the recess of the connecting structure. Such expandable expansion elements can, similar to a dowel, protrude into corresponding hollow undercuts of the recess in the connecting structure when they are extended or expanded. The extension and retraction can be reversible or irreversible in different embodiments. Figures 2 and 3 show an embodiment with extendable or retractable expansion elements.In an alternative embodiment, the extension and / or retraction mechanism may comprise undercut sections that are rigidly attached to sash sections and can be extended into or retracted from hollow undercuts of components of the connecting structure by sliding and / or rotating the fitting or individual fitting components of the fitting (see, for example, Figures 11 to 15).

[0050] According to one embodiment, the first undercut section is arranged at a distance from the second undercut section. More specifically, the first undercut section and the second undercut section may not be connected to each other. This ensures a good spatial distribution of the fastening forces and thus a high degree of connection stability.

[0051] According to one embodiment, the fitting is mounted or mountable exclusively in the recess of the connecting structure with a positive fit. An exclusively positive locking of a fitting in a recess of a connecting structure can refer to a configuration in which no further connection component is provided beyond the positive fit. In particular, in a purely positive connection, a material connection, for example, by glue or the like, can be dispensable or absent.

[0052] According to one embodiment, the entire transition between the connecting structure and the fitting is glue-free, in particular adhesive-free. The omission of adhesive, such as glue or the like, between the fitting and components of the connecting structure allows the components of the connecting structure to be releasably connected to one another. Furthermore, the omission of adhesive or glue ensures a particularly simple connection.

[0053] According to another embodiment, the assembly comprises adhesive, in particular glue, at a transition between the connecting structure and the fitting. If a particularly strong connection force between the fitting and the connecting structure is desired, glue or adhesive can be applied between the fitting and the connecting structure.

[0054] According to one embodiment, the machining tool is designed as an end mill, a combination of end mill and drill, a chain milling tool, or an oscillating tool. If the machining tool is designed as an end mill, the entire recess can be formed using such an end mill. It is also possible to use a combination of end mill and drill, whereby, for example, a hollow central section (and possibly the hollow wing sections) is first drilled using the drill, and the remaining hollow structures of the recess are subsequently formed using an end mill. According to a further embodiment, a chain milling tool can be used, with which even very complex and heavily undercut recesses can be manufactured. The same applies to an oscillating tool, which can also produce recesses of various geometries in a very flexible manner.

[0055] Further embodiments of the invention are described below with reference to the figures.

[0056] They show:

[0057] Figure 1 shows two views of connecting structures according to embodiments of the invention.

[0058] Figure 2 is a cross-sectional view of a fitting in a retracted state in components according to an embodiment of the invention.

[0059] Figure 3 is a cross-sectional view of the fitting according to Figure 2 in an extended state.

[0060] Figure 4 is a plan view of an extension and / or retraction mechanism of a fitting according to an embodiment of the invention.

[0061] Figure 5 is a cross-sectional view of a fitting in components according to a further embodiment of the invention.

[0062] Figure 6 is a plan view of the fitting according to Figure 5.

[0063] Figure 7 three-dimensional views of prototypes of fittings made of biogenic materials according to exemplary embodiments of the invention.

[0064] Figures 8 to 10 show views of three connecting structures according to exemplary embodiments of the invention. Figures 11 to 15 show three-dimensional views of structures obtained during the connection of two components of a connecting structure by means of a fitting according to an exemplary embodiment of the invention.

[0065] Figures 16 to 18 show machining tools according to exemplary embodiments of the invention.

[0066] Figure 19 and Figure 20 show components of connecting structures according to exemplary embodiments of the invention, machined by means of machining tools according to Figure 16 to Figure 18.

[0067] Corresponding elements are designated with corresponding reference symbols in different figures.

[0068] Before exemplary embodiments of the invention are explained in more detail with reference to the figures, some general considerations are described on the basis of which exemplary embodiments of the invention were found.

[0069] According to one embodiment of the invention, a connecting structure comprising at least two components that form a common, complex-shaped recess is positively connected by inserting a substantially inversely shaped fitting. The fitting can, for example, have selectively extendable undercut sections starting from two wing sections, which can be extended into corresponding hollow undercuts in the recess by actuating an extension and / or retraction mechanism. If the undercut sections are extended into the hollow undercuts, a stable and (for example, purely) positive-locking connection can be formed between the connecting structure and the fitting. This makes it easy to create a highly reliable and durable connection between components using a fitting and a correspondingly shaped recess in the two components.

[0070] Furthermore, a corresponding machining tool can be provided that is configured to form a recess in a connecting structure comprising two or more components, said recess having a hollow central section, hollow wings, and hollow undercuts at both opposite ends of the recess. Such a machining tool can particularly advantageously be designed as a handheld device, for example, as a power tool, in particular configured as an end mill. Using such a machining tool, the recess can preferably be formed by removing material.

[0071] For example, the machining tool can be designed as an end mill, the end of which is shaped so that the respective hollow undercut of the recess can also be formed. Alternatively, the recess can first be formed in sections using a drill and subsequently using a milling cutter. According to a further embodiment, a chain milling tool can be used to produce the recess. According to a further embodiment, the machining tool can be designed as an oscillating tool that can, for example, be moved back and forth to form the recess.

[0072] The fitting can be shaped essentially inversely to the recess and can be designed as a single-part or multi-part component. If the fitting is designed as a single-part component, the user can handle the fitting in one piece, which provides reliable protection against incorrect operation. According to one embodiment of the invention, a recess can be formed in components to be connected, which can be used as an undercut recess produced by removing material in a drilled hole as the basis for forming a positive connection. For example, such a recess can be manufactured using a stepped end mill. Such a recess in components to be connected can be used together with a corresponding fitting. This enables, in particular, the production of plate-shaped corner connections between components to be connected.This can be advantageously used in both artisanal and industrial furniture and interior design for movable property and real estate. The described configuration is particularly advantageous for anchoring connecting fittings. According to one embodiment, the connection of components with a common recess can be realized using at least one fitting in the form of a self-tightening connector. Optionally, but not necessarily, the components to be connected can also be glued. Such a connection structure can be formed, for example, based on wood fiberboard (e.g., Homanit HDF, for example with a thickness of no more than 4 mm, for example 3 mm or 2.8 mm). This enables a reliable and invisible connection of components with particular advantages in furniture and interior design.

[0073] According to one exemplary embodiment of the invention, a fitting or dowel system for wood connections can be provided. For this purpose, a milling recess can be made in the wood of the components to be connected to accommodate the fitting or dowel. The recess, for example designed as a milling recess, can have an undercut at the end, for example at the bottom of the drill hole. A fitting that engages in this undercut can be used as the dowel. Thus, a purely form-fitting connection can be formed, for which no glue or the like needs to be used, but can be used. The fitting or dowel engages in a form-fitting manner in the undercut in the wood of the components. This can make it possible to provide an invisible, removable furniture connector.

[0074] A fitting according to an exemplary embodiment of the invention can be provided with a distinctive cross-sectional shape, which can have a central section (for example, in the form of a central round dowel) with wing sections attached to the sides. Advantageously, but optionally, tongues can be used to increase the glue surface.

[0075] A connecting structure fitting system according to an exemplary embodiment of the invention comprises a fitting with a distinctive design of its interfaces to the components to be connected, which can be designed in particular as wooden components or wood-based components. For example, the components to be connected can be the body sides and bases of a device, such as a piece of furniture. By means of fittings according to exemplary embodiments of the invention, the wide and narrow surfaces of components to be connected can be coupled, in particular locked to one another. A connecting structure fitting system according to an exemplary embodiment of the invention can be used with a machining tool, in particular a handheld device, for the machining of the component recesses.Such a machining tool can be used after a crack (e.g., a pencil crack), although in other embodiments, milling tools can be used for CNC (Computerized Numerical Control)-controlled machining. A machining tool designed as a handheld device can, for example, be designed as a battery-operated device. For example, such a handheld device can be designed with digital control via a device display. For example, such a handheld device can be clamped to a workpiece to be machined before the necessary movements are carried out under motor control. In particular, according to one embodiment of the invention, a machining tool in the form of a handheld device can be provided for creating the recesses in the components.

[0076] The geometry of the component recess created by machining can advantageously enable a positive fit (in particular, a precise filling of the corresponding recess) of the fitting. Creating a positive fit is particularly advantageous when the positive fit is created at the base of the respective recess (i.e., at the maximum depth within the component), as this increases the usable mechanical force cone in the component (preferably made of wood or wood-based material) against axial pull-out of the fitting or fitting elements. The geometry of the component recess created by machining simultaneously defines the available installation space for the various matching connecting fittings.Under the exemplary assumption that a small (for example, a maximum 6 mm hole) drilled on the wide surface side as an access hole for actuating the fitting should preferably be located on the longitudinal axis of the recess, the geometry of the component recess can provide the installation space used for the fitting at least along this axis.

[0077] For example, in the fitting, the diameter of the central section, which may be configured as a central cylinder, may be 10 mm (e.g., within a range of 6 mm to 15 mm), while the wing sections may, for example, have a height of 6 mm (e.g., within a range of 4 mm to 10 mm). In particular, a fitting according to an exemplary embodiment of the invention with components configured as wood-based panels may have a thickness in a range of 10 mm to 50 mm, for example, 10 mm, 12 mm, 15 mm, 16 mm, or 19 mm (the latter panel thickness frequently being used in furniture and interior design).

[0078] An access hole used to drive the fitting lock can, for example, be made in the cabinet base on the inside of a cabinet. Such a tool access hole can, for example, be formed with a diameter of 5 mm (more generally, with a diameter in a range of 3 mm to 10 mm). The associated drive can, for example, be an Allen drive or an AW drive. Such a drive can, for example, be implemented at a distance of 7.5 mm from the component edge (more generally, at a distance in a range of 5 mm to 12 mm). The associated operating tool can, for example, be an angled tool (e.g., an Allen key) or a flexible tool (e.g., a screwdriver with a flexible shaft).

[0079] For the positive locking of the fitting in the recess of the connecting structure, joining, assembling, pressing, pressing in, sliding into one another, hanging in, locking in, spring-loaded spreading, screwing, clamping, stapling, wedging and / or bracing can be used.

[0080] Figure 1 shows two views of connecting structures 100 according to exemplary embodiments of the invention. The upper illustration in Figure 1 clearly shows a milling contour in a narrow panel surface. The lower illustration in Figure 1 shows a cabinet side viewed from above. The configuration in Figure 1 can be used, for example, as a panel corner connecting structure.

[0081] More specifically, Figure 1 shows three examples of a connecting structure 100 formed from two components 102, 104. The components 102, 104 according to Figure 1 can be designed as panels and can comprise wood. A hollow recess 106 is formed, for example, milled, in the two adjacent components 102, 104. The recess 106 serves to positively accommodate a fitting 108 (not shown in Figure 1, see, for example, Figures 2 and 3).

[0082] As shown in Figure 1, each of the three recesses 106 shown has a circular-cylindrical central hollow section 110, which extends partly into the component 102 and partly into the component 104. The sections of the circular-cylindrical central hollow section 110 in the two components 102, 104 are coaxially and continuously joined to one another.

[0083] Starting from the central hollow section 110, the respective recess 106 further has a first hollow wing section 112 extending along a first direction 182. According to the upper illustration of Figure 1, the first direction 182 extends to the left. Furthermore, also starting from the central hollow section 110, the respective recess 106 has a second hollow wing section 114 extending along a second direction 184. According to the upper illustration of Figure 1, the second direction 184 extends to the right. Thus, the first direction 182 and the second direction 184 are opposite one another and form an angle of 180° with one another. Clearly, each of the hollow wing sections 112, 114 has the shape of a hollow strip with rounded hollow ends.

[0084] Furthermore, for each of the three recesses 106 according to Figure 1, a first hollow undercut 116 is formed in the first component 102, which extends from a free first end of the central hollow section 110, the first hollow wing section 112, and the second hollow wing section 114. According to Figure 1, the first hollow undercut 116 is formed entirely in the first component 102. In particular, the first hollow undercut 116 can be formed as a circumferential hollow undercut, ie, as a closed hollow ring structure.

[0085] Furthermore, for each of the three recesses 106 according to Figure 1, a second hollow undercut 118 is formed in the second component 104, axially spaced from the first hollow undercut 116, which extends from an opposite, other free second end of the central hollow section 110, the first hollow wing section 112, and the second hollow wing section 114. According to Figure 1, the second hollow undercut 118 is formed entirely in the second component 104.

[0086] In particular, the second hollow undercut 118 can be formed as a circumferential hollow undercut, i.e., as a closed hollow ring structure. The second hollow undercut 118 is shown in Figure 1 at the top with dashed lines as a circumferential, closed hollow undercut.

[0087] Thus, according to Figure 1, the first hollow undercut 116 and the second hollow undercut 118 are each undercut along their entire circumference relative to the central hollow section 110, the first hollow wing section 112, and the second hollow wing section 114. The first hollow undercut 116 and the second hollow undercut 118 each have an outline (see the dashed lines for the second hollow undercut 118 in the upper illustration according to Figure 1) defined by two end semicircles and two linear and parallel connecting lines between the semicircles.

[0088] Furthermore, Figure 1 shows that the first component 102 has a first part of the central hollow section 110, a first part of the first hollow wing section 112, a first part of the second hollow wing section 114, and the entire first hollow undercut 116. The second component 104, on the other hand, has a second part of the central hollow section 110, a second part of the first hollow wing section 112, a second part of the second hollow wing section 114, and the entire second hollow undercut 118.

[0089] For the middle and right-hand embodiments according to Figure 1, it is also shown that the first component 102 has an access hole 120 opening into the recess 106 for tool-assisted actuation of an extension and / or retraction mechanism 132 of the fitting 108 (see description of Figures 2 and 3) when the fitting 108 is inserted into the recess 106.

[0090] The upper view of Figure 1 shows that the central hollow section 110 on the one hand and the first hollow wing section 112 and the second hollow wing section 114 on the other hand have different maximum diameters d, D perpendicular to the first direction 182 and perpendicular to the second direction 184 in a viewing direction along an axial direction 180 of the central hollow section 110. In the example shown, the maximum diameters d<D. Alternativ kann auch d> D apply, see for example Figure 10. By specifying the parameters d and D, the stability properties of the connection can be adjusted. Now referring to the lower illustration of Figure 1, the central hollow section 110, the first hollow wing section 112 and the second hollow wing section 114 can be viewed together in a direction perpendicular to the axial direction 180 of the central hollow section 110 and perpendicular to the first direction 182 and the second direction 184 (iein a view of the first component 102 perpendicular to the plane of the paper in Figure 1) be rectangular. This ensures good and uniform stability of the connection and allows the connection of thin plates. Referring again to the lower illustration of Figure 1, the first hollow undercut 116 and the second hollow undercut 118 are not directly physically connected to one another, but instead are axially spaced from one another. This distributes the anchoring forces in the components 102, 104 in a spatially advantageous manner. Figure 1 therefore shows, in two different views, three different embodiments of recesses 106 in components 102, 104 of a connecting structure 100. These can be manufactured, for example, using an end mill or a combination of drill and end mill. An associated, one-piece, handleable fitting 108 can be inserted into the interior of each recess 106.More specifically, the entire fitting 108 can be partially inserted into one of the components 102, 104 before the other of the components 102, 104 is placed thereon, thereby receiving the protruding remainder of the fitting 108. Through an access hole 120 leading from an outer one of the components 102, 104 to the recess 108, a tool (for example, a screwdriver or a cordless drill) can be brought into engagement with a drive (for example, a hexagon drive or a Torx drive) of the fitting 108 in order to actuate its retraction and / or extension mechanism 132 from outside the connecting structure 100.If a user performs such an actuation, undercut sections 128 of the fitting 108 can be inserted into hollow undercuts 116 of the recess 106 and undercut sections 130 of the fitting 108 can be inserted into hollow undercuts 118 of the recess 106 in order to effect a positive locking of the fitting 108 in the recess 106 and thereby to positively lock the components 102, 104 to one another.

[0091] The three embodiments of the recesses 106 according to Figure 1 differ essentially with regard to their proportions of the hollow central section 110 in relation to the hollow wings 112, 114 and the hollow undercuts 116, 118.

[0092] Figure 2 shows a cross-sectional view of a fitting 108 in a retracted state of its undercut sections 130 (and 128, not shown in Figure 2, see Figure 5) in components 102, 104 according to another embodiment of the invention. Figure 3 shows a cross-sectional view of the fitting 108 according to Figure 2 in an extended state of its undercut sections 130 (and 128, not shown in Figure 3). Figure 4 shows a top view of an extension and / or retraction mechanism 132 of the fitting 108 according to Figures 2 and 3.

[0093] Figures 2 and 3 thus depict the fitting 108 for positively receiving in a recess 106 of a connecting structure 100, as shown and described in accordance with Figure 1. More specifically, Figures 2 and 3 depict the fitting 108 in two different operating states, namely with the undercut sections 130 retracted without locking (Figure 2) and with the undercut sections 130 extended and locking in a positive manner (Figure 3). Furthermore, Figures 2 and 3 depict the fitting 108 in a component 104 of a connecting structure 100, which—as shown in Figure 1—is formed from two components 102, 104. A recess 106, into which the fitting 108 has been inserted, is again formed jointly in the two components 102, 104.

[0094] Starting from a solid central section 122 of the fitting 108, a solid first wing section 124 extends along a first direction 186. Furthermore, a solid second wing section 126 extends from the central section 122 along a second direction 188 opposite the first direction 186. A first undercut section (not shown in Figures 2 and 3, see reference numeral 128 in Figure 5) is provided, more precisely, integrally formed, at a free first end of the first wing section 124 and at a free first end of the second wing section 126. Figures 2 and 3 show a second undercut section 130, which is integrally formed at a free second end of the first wing section 124 and the second wing section 126 opposite the first end. Figures 2 and 3 also show in cross section an extension and / or retraction mechanism 132, which is shown in plan view in Figure 4.This is designed to selectively extend and / or selectively retract the first undercut section 128 and the second undercut section 130 transversely to the first direction 186 and transversely to the second direction 188. According to the operating state of Figure 2, the undercut sections 128, 130 are retracted by means of the extension and / or retraction mechanism 132, since the narrow side of the extension and / or retraction mechanism 132 prevents extension of the undercut sections 128, 130. According to the operating state of Figure 3, the extension and / or retraction mechanism 132 has extended the undercut sections 128, 130, since the broad side of the extension and / or retraction mechanism 132 causes extension of the undercut sections 128, 130. A transition between the operating states according to Figure 2 and Figure 3 is thus possible by rotating the extension and / or retraction mechanism 132 by 90° according to Figure 4.Referring to Figure 3, the extension and / or retraction mechanism 132 is configured to selectively extend the first undercut section 128 and the second undercut section 130 in a first transverse direction 190 (vertical according to Figures 2 and 3) and in a second transverse direction 192 (vertical according to Figures 2 and 3) opposite to the first transverse direction 190, perpendicular to the first direction 186 (horizontal according to Figures 2 and 3) and perpendicular to the second direction 188 (horizontal according to Figures 2 and 3). In order to transfer it between the operating states of Figures 2 and 3, the extension and / or retraction mechanism 132 can be configured to be actuated by a user by means of an actuating tool in order to selectively extend and / or retract the first undercut section 128 and the second undercut section 130, respectively.Illustratively, to transition between the extended and retracted states, the extension and / or retraction mechanism 132 can be rotated by 90° according to Figure 3. Therefore, the extension and / or retraction mechanism 132 can be rotationally actuated to selectively extend the first undercut section 128 or the second undercut section 130 and thereby clamp them relative to the components 102, 104. Illustratively, the first undercut section 128 and the second undercut section 130 have expandable expansion elements by actuating the extension and / or retraction mechanism 132, which, by spreading, positively engage in the first hollow undercut 116 or the second hollow undercut 118 of the recess 106 of the connecting structure 100, see Figure 3.

[0095] According to Figure 2 and Figure 3, the fitting 108 includes a plate-shaped first fitting component 140 with a part of the central section 122, the first wing section 124, the second wing section 126, the first undercut section 128 and the second undercut section 130. In addition, the fitting 108 comprises a plate-shaped second fitting component 142 that is symmetrical to the first fitting component 140 and has another part of the central section 122, the first wing section 124, the second wing section 126, the first undercut section 128 and the second undercut section 130. In the illustrated embodiment, the extension and / or retraction mechanism 132 forms a plate-shaped third fitting component 144, which is arranged between the first fitting component 140 and the second fitting component 142 and can be designed as shown in Figure 4.The three fitting components 140, 142, 144 thus form a compact sandwich structure made of structured plates arranged parallel to one another.

[0096] At least part of the fitting 108 can be formed from biogenic material, for example, from wood-based plant material. For example, it is possible for the central section 122, the first wing section 124, the second wing section 126, the first undercut section 128, and the second undercut section 130 to be made from biogenic material, preferably from plant material. In other words, the fitting components 140, 142 can be made from biogenic material, in particular from renewable raw materials. This allows the fitting 108 to be manufactured sustainably. The extension and / or retraction mechanism 132 can be made from metal, ceramic, and / or plastic, for example, to provide high stability, or alternatively also from biogenic material.Furthermore, it is alternatively possible to manufacture the fitting components 140, 142, for example, from metal, ceramic and / or plastic if this is desirable or necessary in an application, for example for reasons of stability.

[0097] Figure 2 shows the plate-shaped extension and / or retraction mechanism 132 in a retracted state, in which the undercut sections 130 are consequently not arranged in a form-fitting manner in the hollow undercuts 118. In order to move from the retracted configuration according to Figure 2 to the extended configuration according to Figure 3, which connects the components 102, 104 in a form-fitting manner, a user can rotate the plate-shaped extension and / or retraction mechanism 132 (for example, by 90°) using an actuating tool. By rotating such a non-rotationally symmetrical retraction and / or extension mechanism 132, ends of the broad side of the extension and / or retraction mechanism 132 can be brought into operative connection with the undercut sections 118 (and correspondingly 116, not shown in Figures 2 and 3).When such an engagement or operative connection is activated (as shown in Figure 3), the retraction and / or extension mechanism 132 can extend the undercut sections 118 (or 116) and thereby positively lock them in the hollow undercuts 118 or 116, see Figure 3. Figure 4 shows a plan view of the plate-shaped extension and / or retraction mechanism 132 of the fitting 108. In the center of the plate-shaped extension and / or retraction mechanism 132 according to Figure 4 there is a recess 170 designed as a drive, which can be engaged and actuated by means of an actuating tool (not shown) for rotating the extension and / or retraction mechanism 132.Guide structures 172, 174 extending into the plate-shaped extension and / or retraction mechanism 132 can, for example, determine the mechanical tension properties of the extension and / or retraction mechanism 132 and / or can, for example, be guidedly engaged by pins of a respective fitting component 140 or 142 while a user actuates the retraction and / or extension mechanism 132 using an actuation tool. As shown in Figure 4, the extension and / or retraction mechanism 132 has a larger (horizontal according to Figure 4) longitudinal extent along its wide side compared to its smaller (vertical according to Figure 4) transverse extent along its narrow side. If the ends of the broad side are in operative connection with undercut sections 128, 130 of the fitting components 140, 142, these undercut sections 128, 130 are extended (for example in the manner shown in Figure 3).If the narrow side of the extension and / or retraction mechanism 132 is in an active position (see, for example, Figure 2), the extension and / or retraction mechanism 132 is retracted.

[0098] Figure 5 shows a cross-sectional view of a fitting 108 in components 102, 104 according to a further embodiment of the invention. Figure 6 shows a top view of the fitting 108 according to Figure 5. More specifically, Figure 5 shows an arrangement 136 with a connecting structure 100 and a fitting 108 that is mounted exclusively in a recess 106 of the connecting structure 100 with a form-fitting fit. Preferably, an entire transition between the connecting structure 100 and the fitting 108 is free of glue or adhesive. Alternatively, adhesive or glue can be provided at a transition between the connecting structure 100 and the fitting 108.

[0099] In the illustration in Figure 5, the fitting 108 is inserted into the recess 106 of the connecting structure 100 comprising the components 102, 104. If, as illustrated in Figure 5 with a rotation arrow, an actuating tool (not shown) (for example, a screwdriver) is brought into engagement with the drive 170, which is designed here as a square, through the feed hole 120, the extension and / or retraction mechanism 132 of the fitting 108 can be moved by rotation. In this case, the retraction and / or extension mechanism (hatched rectangle), shown schematically in an inactive state in Figure 5, can be transferred into an active position (rotated by 90°) in order to thereby trigger a spreading of the undercut sections 128, 130 of the fitting 108.

[0100] In the fitting 108 according to Figures 5 and 6, the first undercut section 128 is arranged at a distance from the second undercut section 130. More specifically, the first undercut section 128 and the second undercut section 130 are not connected to each other by direct physical contact. This results in a reliable undercut connection with spatially distributed force introduction.

[0101] Figure 7 shows three-dimensional views of prototypes of fittings made of biogenic materials according to exemplary embodiments of the invention.

[0102] Figure 7 shows, for different biogenic materials, more specifically plant materials, that fittings according to exemplary embodiments of the invention can be produced using appropriate pressing techniques, preferably using a suitable binder. These meet the requirements for mechanical strength and also allow the production of undercut sections, preferably formed integrally with the rest of the fittings, which can be selectively extended or retracted by means of an extension and / or retraction mechanism (for example, made of a non-biogenic material or also of a biogenic material).

[0103] In particular, fittings or dowels according to exemplary embodiments of the invention can be manufactured entirely or partially from renewable raw materials. Figure 7 shows examples of what is technically possible using primary forming and forming processes. More specifically, Figure 7 shows fittings made of wood fibers (from left to right):

[0104] 1. Shavings from 3DF (a re-formable MDF board with a binder)

[0105] 2. Chips / fibers of the same 3DF plate

[0106] 3. coarse "chips" of the same 3DF board

[0107] 4. two 5 mm thick layers of the same 3DF plate (on this basis, fittings can be manufactured according to a preferred embodiment)

[0108] 5. Poplar sawdust with urea-formaldehyde adhesive powder

[0109] 6. Native poplar wood

[0110] Figure 8, Figure 9 and Figure 10 each show two views (corresponding to those of Figure 1) of connection structures 100 according to embodiments of the invention.

[0111] The lower illustrations of Figures 8 to 10 show that the central hollow section 110 can be, for example, a cylinder section (see Figure 8), a plate section (see Figure 10), or a structure with, in plan view, two round end sections and two straight connecting lines connecting them (see Figure 9). Figures 8 to 10 thus illustrate that recesses 106 in components 102, 104 of connecting structures 100 can be manufactured in entirely different geometries. What all of these embodiments have in common, however, is that the recesses 106 each have a hollow central section 110, hollow wing sections 112, 114 extending therefrom on both sides, and axially opposite hollow undercuts 116 and 118, respectively.

[0112] Figures 11 to 15 show three-dimensional views of structures obtained during the connection of two components 102, 104 of a connecting structure 100 by means of a fitting 108 according to an exemplary embodiment of the invention.

[0113] In this embodiment, the fitting 108 has a first fitting component 140 with a part of the central section 122, the first wing section 126, the second wing section 126, the first undercut section 128, and the second undercut section 130. Furthermore, the fitting 108 has a second fitting component 142 with another part of the central section 122, the first wing section 124, the second wing section 126, the first undercut section 128, and the second undercut section 130. In the described embodiment, the extension and / or retraction mechanism 132 is formed as part of the first fitting component 140 and / or the second fitting component 142 and is realized by correspondingly rotating the correspondingly shaped fitting components 140, 142 relative to one another.

[0114] More specifically, Figures 11 to 15 show a self-tightening fitting 108 for glued joints made of Homanit HDF boards. The fitting 108 can be laser-cut or punched from Homanit HDF boards and inserted into the recess 106 of components 102, 104 to be joined using white glue. This self-tightening fitting 108 or connector can be made of wood fiberboard (or plywood), which is why it is not only ecologically sustainable but also exhibits high holding force.

[0115] Figures 11 to 15 further show two components 102, 104 made of wood composite that are to be connected to one another. Each of these components has a partial recess, whereby the two components 102, 104, when assembled, can jointly form a recess 106 with the features described above. This recess can, in particular, have hollow undercuts 116 and 118, respectively.

[0116] Figure 11 shows two initially separately handled fitting components 140, 142 of the fitting 108, which can be configured as described above. In particular, the fitting components 140, 142 have undercut sections (shown above with reference numerals 128, 130). Furthermore, the fitting components 140, 142 are provided with guide structures (shown above with reference numerals 172, 174) for adjusting their tension properties.

[0117] Figure 12 shows the constituents according to Figure 11 after fitting component 140 has been inserted into the partial recess of the first component 102.

[0118] Figure 13 shows the representation according to Figure 12, after the other fitting component 142 has been introduced together with the fitting component 140 into the partial recess of the component 102. The fitting components 140, 142 are arranged relative to one another in such a way that their undercut sections 128, 130 are arranged at four corners in the component stack, wherein two corners of undercut sections of the fitting component 140 and the other two corners of

[0119] undercut sections of the fitting component 142.

[0120] Figure 14 shows the arrangement according to Figure 13 after a section of the stacked fitting components 140, 142 protruding from the component 102 has been partially inserted into the partial recess of component 104.

[0121] Finally, Figure 15 shows the arrangement after the protruding portion of the stacked fitting components 140, 142 has been fully inserted into component 104. This results in an arrangement 136 consisting of a fitting 108 and components 102, 104 that are positively connected to one another.

[0122] Figures 16, 17, and 18 show machining tools 134 according to exemplary embodiments of the invention. More specifically, Figures 16 to 18 show end mills as examples of machining tools 134 with which recesses 106 can be manufactured in components 102 and 104, respectively, with hollow undercuts 116 and 118, respectively.

[0123] Figure 19 and Figure 20 show components 104 of connecting structures 100 machined by means of machining tools 134 according to Figure 16 to Figure 18 according to an exemplary embodiment of the invention.

[0124] Additionally, it should be noted that "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

Claims

P a t e n t a n s p r ü c h e 1. A connecting structure (100) formed from at least two components (102, 104), wherein a recess (106) for positively receiving a fitting (108), in particular a fitting (108) according to one of claims 14 to 27, is formed in the at least two components (102, 104), wherein the recess (106) comprises: a first hollow wing section (112) extending from a central hollow section (110) of the recess (106) along a first direction (182); a second hollow wing section (114) extending from the central hollow section (110) of the recess (106) along another, for example opposite, second direction (184); a first hollow undercut (116) at a free first end of the central hollow section (110), the first hollow wing section (112) and / or the second hollow wing section (114);and a second hollow undercut (118) arranged at a distance from the first hollow undercut (116) at a free second end of the central hollow section (110), the first hollow wing section (112) and / or the second hollow wing section (114) opposite the first end; 2. Connecting structure (100) according to claim 1, designed as a plate corner connecting structure.

3. Connecting structure (100) according to claim 1 or 2, wherein the central hollow portion (110) is a cylinder portion, a plate portion or a structure having, in plan view, two round end portions and two straight connecting lines connecting them.

4. The connecting structure (100) according to any one of claims 1 to 3, wherein the at least two components (102, 104) comprise two plates.

5. Connecting structure (100) according to one of claims 1 to 4, wherein the first hollow undercut (116) and / or the second hollow undercut (118) is undercut along its entire circumference relative to the central hollow section (110), the first hollow wing section (112) and the second hollow wing section (114).

6. The connecting structure (100) according to any one of claims 1 to 5, wherein the first hollow undercut (116) and / or the second hollow undercut (118) has an outline defined by two semicircles and two linear connecting lines between the semicircles.

7. Connecting structure (100) according to one of claims 1 to 6, wherein the at least two components (102, 104) comprise wood, in particular plywood and / or a wood fiber material.

8. The connecting structure (100) according to any one of claims 1 to 7, wherein a first component (102) of the at least two components (102, 104) comprises a part of the central hollow section (110), a part of the first hollow wing section (112), a part of the second hollow wing section (114) and the entire first hollow undercut (116), and wherein a second component (104) of the at least two components (102, 104) comprises another part of the central hollow section (110), another part of the first hollow wing section (112), another part of the second hollow wing section (114) and the entire second hollow undercut (118).

9. Connecting structure (100) according to one of claims 1 to 8, wherein at least one of the at least two components (102, 104) has a recess (106) opening access hole (120) for actuating, in particular by means of an actuating tool, an extension and / or retraction mechanism (132) of the fitting (108) when the fitting (108) is inserted into the recess (106).

10. Connecting structure (100) according to one of claims 1 to 9, wherein the central hollow section (110) on the one hand and the first hollow wing section (112) and the second hollow wing section (114) on the other hand have different maximum diameters (d, D) transverse to the first direction (182) and transverse to the second direction (184) in a viewing direction along an axial direction (180) of the central hollow section (110).

11. The connecting structure (100) according to any one of claims 1 to 10, wherein the central hollow portion (110), the first hollow wing portion (112) and the second hollow wing portion (114) are together rectangular in a viewing direction perpendicular to an axial direction (180) of the central hollow portion (110) and perpendicular to the first direction (182) and the second direction (184).

12. The connecting structure (100) according to any one of claims 1 to 11, wherein the first hollow undercut (116) and the second hollow undercut (118) are not connected to each other.

13. Connecting structure (100) according to one of claims 1 to 12, wherein the first hollow undercut (116) is annularly closed and / or the second hollow undercut (118) is annularly closed.

14. Fitting (108) for positively receiving in a recess (106) of a connecting structure (100), in particular a connecting structure (100) according to one of claims 1 to 13, which consists of at least two components (102, 104), wherein the recess (106) is formed jointly in the at least two components (102, 104), wherein the fitting (108) comprises: a first wing section (124) extending from a central section (122) along a first direction (186); a second wing section (126) extending from the central section (122) along another, for example opposite, second direction (188); a first undercut section (128) at a free first end of the central section (122), the first wing section (124) and / or the second wing section 126); a second undercut section (130) at a free second end of the central section (122), the first wing section (124) and / or the second wing section (126), opposite the first end;and an extension and / or retraction mechanism (132) configured to selectively extend and / or selectively retract the first undercut portion (128) and / or the second undercut portion (130), for example transversely to the first direction (186) and transversely to the second direction (188); 15. Fitting (108) according to claim 14, which is formed at least partially, in particular predominantly, further in particular completely, from biogenic material.

16. Fitting (108) according to claim 14 or 15, which is formed predominantly or entirely from plant material.

17. Fitting (108) according to one of claims 14 to 16, wherein the Central section (122), the first wing section (124), the second wing section (126), the first undercut section (128) and the second Undercut section (130) is at least partially made of biogenic material, in particular of plant material.

18. Fitting (108) according to one of claims 14 to 17, wherein the extension and / or retraction mechanism (132) is made of metal, ceramic and / or plastic.

19. Fitting (108) according to one of claims 14 to 18, wherein the extension and / or retraction mechanism (132) is designed to selectively extend the first undercut section (128) and the second undercut section (130) in a first transverse direction (190) and in a second transverse direction (192) opposite to the first transverse direction (190), transverse to the first direction (186) and transverse to the second direction (188).

20. Fitting (108) according to one of claims 14 to 19, wherein the extension and / or retraction mechanism (132) is configured to be actuated by a user or an actuating tool to selectively extend and / or retract the first undercut portion (128) and / or the second undercut portion (130).

21. Fitting (108) according to one of claims 14 to 20, wherein the extension and / or retraction mechanism (132) is designed to be actuated by turning and / or sliding in order to selectively extend and / or retract the first undercut section (128) and / or the second undercut section (130).

22. Fitting (108) according to one of claims 14 to 21, wherein the extension and / or retraction mechanism (132) is designed to be actuated to move the first undercut portion (128) and / or the second undercut portion (130) selectively and thereby clamp it relative to at least one of the at least two components (102, 104).

23. Fitting (108) according to one of claims 14 to 22, comprising: a first fitting component (140) having a part of the central section (122), the first wing section (124), the second wing section (126), the first undercut section (128), and the second undercut section (130); and a second fitting component (142) having another part of the central section (122), the first wing section (124), the second wing section (126), the first undercut section (128), and the second undercut section (130); wherein the extension and / or retraction mechanism (132) forms a third fitting component (144) that is arranged at least partially between the first fitting component (140) and the second fitting component (142).

24. Fitting (108) according to one of claims 14 to 22, comprising: a first fitting component (140) having a part of the central section (122), the first wing section (126), the second wing section (126), the first undercut section (128), and the second undercut section (130); and a second fitting component (142) having another part of the central section (122), the first wing section (124), the second wing section (126), the first undercut section (128), and the second undercut section (130); wherein the extension and / or retraction mechanism (132) is formed as part of the first fitting component (140) and / or the second fitting component (142).

25. Fitting (108) according to one of claims 14 to 24, wherein the first undercut section (128) and / or the second undercut section (130) has spreading elements which can be spread by actuating the extension and / or retraction mechanism (132) and which, by spreading, positively engage in a first hollow undercut (116) and / or in a second hollow undercut (118) of the recess (106) of the connecting structure (100).

26. Fitting (108) according to one of claims 14 to 25, wherein the first undercut portion (128) is arranged at a distance from the second undercut portion (130).

27. Fitting (108) according to one of claims 14 to 26, wherein the first undercut portion (128) and the second undercut portion (130) are not connected to each other.

28. An arrangement (136) comprising: a connecting structure (100) according to one of claims 1 to 13; and a fitting (108) according to one of claims 14 to 27, which is or can be mounted in a form-fitting manner in the recess (106) of the connecting structure (100).

29. Arrangement (136) according to claim 28, wherein the fitting (108) is or can be mounted exclusively in a form-fitting manner in the recess (106) of the connecting structure (100).

30. Arrangement (136) according to claim 28 or 29, wherein an entire transition between the connecting structure (100) and the fitting (108) is glue-free, in particular adhesive-free.

31. Arrangement (136) according to claim 28, comprising adhesive, in particular glue, at a transition between the connecting structure (100) and the fitting (108).

32. Machining tool (134) for forming a recess (106) in a connecting structure (100) formed from at least two components (102, 104), wherein the recess (106) for positively receiving a fitting (108) is formed jointly in the at least two components (102, 104), wherein the machining tool (134) is designed to form in the connecting structure (100): a first hollow wing section (112) extending from a central hollow section (110) of the recess (106) along a first direction (182); a second hollow wing section (114) extending from the central hollow section (110) of the recess (106) along another, for example opposite, second direction (184); a first hollow undercut (116) at a free first end of the central hollow section (110), the first hollow wing section (112) and / or the second hollow wing section (114);and a second hollow undercut (118) arranged at a distance from the first hollow undercut (116) at a free second end of the central hollow section (110), the first hollow wing section (112) and / or the second hollow wing section (114) opposite the first end; 33. Machining tool (134) according to claim 32, designed as an end mill, a combination of end mill and drill, a chain milling tool or an oscillating tool.

34. A method for the positive connection of at least two components (102, 104) of a connecting structure (100) according to one of claims 1 to 13 by means of a fitting (108) according to one of claims 14 to 28, the method comprising: Forming the recess (106) in the at least two components (102, 104) of the connecting structure (100); Inserting the fitting (108) into the recess (106) with the first undercut section (128) and / or the second undercut section (130) retracted; and subsequently actuating the extension and / or retraction mechanism (132) to extend the first undercut section (128) into the first hollow undercut (116) and / or the second undercut section (130) into the second hollow undercut (118), in order to thereby fasten the fitting (108) in the recess (106) with a positive connection of the at least two components (102, 104).

35. The method according to claim 34, wherein the forming and / or the actuating is carried out by means of a machining tool (134) according to claim 32 or 33.

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