CH715833A1 - Key, manufacturing process and identification system. - Google Patents

Abstract

A key part is produced using an additive manufacturing process. This makes use of the knowledge that additive manufacturing processes result in inhomogeneities in the structure of the manufactured body, at least under suitable conditions. According to the invention, these inhomogeneities are used to form the key information. This is done in that at least one measured variable, which is dependent on these inhomogeneities, is read out and recorded after the production of the key section. It thereby forms the coding or at least a part of it.

Description

The invention relates to keys, methods for producing keys and key-based systems.

Key-based systems are systems in which possible users encoded keys are made available which can be checked in a suitable manner, for example mechanically and / or electronically, and grant the user authorization if the coding is correct. Locking systems are particularly widespread in which a suitable key can actuate a lock device, for example with a lock cylinder, or enables its actuation, while such actuation is not possible if there is no or only an unsuitable key. Other key-based systems entitle the user of a suitable key to other actions, e.g. to operate a device, to access a computer system, etc.

Mechanically coded keys on the one hand and keys with electronic coding on the other hand are particularly known. In the case of mechanically coded keys, the coding is in the form of mechanical features specifically attached to the key, for example a key-specific serrated profile or a pattern of bores or paths, which are scanned by suitable mechanical scanning means of the lock device. The lock device can, for example, contain a lock cylinder, the movable element (cylinder core, rotor) of which can be moved in an element fixed to the housing (stator) in order to operate a lock, if the coding of the key matches that of the scanning device (e.g. mechanical tumblers).

[0004] Electronically encoded keys can take very different physical forms. Known, for example, are keys in the form of a conventional mechanical key with a key shaft - possibly with additional mechanical coding - and key head, with a chip with an electronic coding also being installed which can be read out by a reading device. Keys in the form of chip cards, for example, are also known. In the case of electronic keys, the decision about authorization of the key for the present lock device or other authorization device of the key-based system is made using a suitable authentication process.

In addition to the release of a rotational movement of a lock cylinder rotor in a lock cylinder stator, there are additionally or alternatively many other possibilities for how the lock device reacts to a recognized authorization, including the electromechanical coupling or decoupling of parts of a lock relative to one another, or the release of an electronic transaction, etc. In the most general case, the user carrying the key is enabled to perform an action on the device, which he could not take without this authorization, and / or such an action is performed automatically by the device .

All known key-based systems have in common that it should be prevented that unauthorized persons can copy a key. In the case of mechanical keys, a certain amount of copy protection can be achieved through a complicated design that is difficult to manufacture, possibly with moving parts. With sufficient effort, however, such copy protection can be overcome. There are electronic copy protection systems for electronic keys, but they also have their limits.

[0007] WO 2016/062407 proposes a quantum-physically coded metallic key, the coding of which is formed by quantum-physical changes in the metal structure that are neither visible nor palpable. The reading takes place via so-called electromagnetic scanning. In this way, the key should not be able to be copied or only with considerable effort. WO 2016/062407 is largely silent about how such a quantum physical coding can be implemented. Regardless of this, in a specific implementation, the change in the metal structure will have to be carried out in a certain way using certain rules, which rules contain the coding. At least for someone who knows these rules for a specific key - be it that he has acquired them legally or illegally - it will therefore be possible to reproduce or copy an existing key. In addition to the unresolved question of concrete feasibility, this is a second disadvantage of the teaching of WO 2016/062407.

It is the object of the present invention to provide an identification system, for example a locking system, which overcomes the disadvantages of the prior art and which, in particular, improves the protection against unauthorized copies. Likewise objects of the invention are making available a key for such an identification system, making available a corresponding production method and / or making available a use.

According to one aspect of the invention, it is proposed to produce an identification area using an additive manufacturing method. Additive manufacturing processes (also called additive manufacturing processes or sometimes generative manufacturing processes, the best known of which are often also called "3D printing processes") have already been proposed for the production of mechanical keys, as they are well suited for individually mechanically coded identification areas, for example shafts of mechanical keys to manufacture. In contrast to these approaches from the prior art, however, the invention is not based on the fact that individually shaped keys are specifically produced, with geometric coding features (holes, spikes or the like) at positions provided for this. Rather, according to the approach of the invention, use is made of the knowledge that in the case of additive manufacturing processes, at least under suitable conditions, inhomogeneities result in the structure of the manufactured body. These result, for example, from a complex and non-deterministically predictable dynamics of the weld pool that results when the process is used. According to the invention, these inhomogeneities are used to provide the identification information, i.e. for example the key information. This takes place in that at least one measured variable, which is dependent on these inhomogeneities, is read out and recorded after the identification area has been produced. It thereby forms the identification information with the coding or at least part of it. These coding data - possibly further processed - are then made available to the authorization device or other identification device. The identification - for example combined with a decision on the authorization of a key carrying the identification area - is then carried out in each case on the basis of the results of a measurement of the at least one measured variable. This can mean: If the identification area is identical to a previously recorded identification area that carries an authorization (e.g. as part of an authorized key), an authorization exists. If, on the other hand, the measurement shows that the identification area is not one of those whose coding data is available and is appropriately noted (for example belonging to an authorized key), there is also no authorization.

In the present text, the term "authorization device" refers to a lock device, for example a lock cylinder or another device that authorizes or does not authorize the user to perform an action (e.g. unlocking) depending on the identification information that is read out and forms the coding.

In contrast to the prior art, according to one approach of the present invention, a coding is not first established and then a key is produced with the specified coding. Rather, conversely, the key with the identification area is first produced. Only then is a code read out, which results from fluctuations in the manufacturing process that cannot be conclusively controlled and a unique structure of the identification area resulting therefrom. This coding is then stored, with direct measurement data or data derived therefrom being possible as the coding.

This results in the lack of copiability as an intrinsic property of the key. Even if exactly the same conditions prevail when the key is produced again, the second key resulting from the renewed production will not be identical due to the uncontrollable fluctuation. In this regard, the approach according to the invention is comparable to the baking of bread: even if a baker uses exactly the same dough mixture twice and bakes under exactly the same conditions, the arrangement and distribution of the pores resulting in the bread will always be different. The present invention exploits the lack of identity.

Another application of an identification system according to the invention, in addition to the application for keys and authorization devices, is to ensure traceability and / or security against forgery. For example, in a manufacturing process, parts that are actually identical can be provided with an identification area in a manner according to the invention, and this identification area can then be detected with a reading device. The parts can later be identified at any time by reading out the identification area again. In contrast to the application of a serial number, a deterministic code or the like, the identification is absolutely tamper-proof in this application too, in that it is impossible to apply a code recorded by the original manufacturer subsequently, for example by copying.

In general, additive manufacturing processes are optimized for the greatest possible homogeneity, even if the manufacture of a completely homogeneous body remains an ideal goal that has not been achieved. In embodiments of the present invention, in contrast thereto, conditions (manufacturing parameters) can be selected in additive manufacturing such that sufficiently large inhomogeneities result. In these embodiments, too, however, the inhomogeneities are non-deterministic, i.e. not fully controllable during manufacture.

In particular, the manufacturing parameters can be chosen so that there is a noticeably reduced homogeneity in comparison to given specifications (e.g. that the number and / or size of defects is at least a factor of 2, in particular at least a factor of 10 higher than in the case of production according to known specifications), but that the process still works in that a coherent object can be produced.

The average distribution of the inhomogeneities (number and size) is set so that they can both be recognized and resolved by the selected sensor and form enough permutations on the size of the key to be considered unique. For the characteristic dimension D of the inhomogeneities (flaws, artifacts, etc., e.g. size of the pores or expansion of local maxima / minima in the case of a fluctuating interface) it can therefore apply that this must be at least as large as the minimum resolution of the sensor, but at most so large that enough inhomogeneities and thus sufficient permutations can be accommodated in one identification area: Dmin, resolution≤Dinhomogeneity≤Dmax, permutation.

In particular, there are not only microscopic inhomogeneities, but (also) mesoscopic (characteristic dimension D between 1 nm and 1 μm) or macroscopic (characteristic dimension D greater than 1 μm) inhomogeneities. In many embodiments, at least macroscopic inhomogeneities with a characteristic dimension of between 1 μm and 1 mm can be measured. This does not rule out the fact that there are additional inhomogeneities on a smaller scale. It is crucial that inhomogeneities are measurable and significant when averaging over the size scale mentioned (for example, macroscopically).

In many embodiments, the inhomogeneities include surfaces (in particular due to pores in the material structure) or interfaces between different materials (for example magnetic and non-magnetic materials and / or materials with different electrical conductivities). However, it is also not ruled out that the inhomogeneities exist between areas with merely different crystallographic or other properties.

In a group of exemplary embodiments, the additive manufacturing process, with which at least the identification area is produced, includes local heating to generate a molten pool of material by means of irradiated energy, for example a laser beam, and the displacement of the energy irradiation location relative to the material.

A first category of exemplary embodiments of such methods are methods from the family of powder bed fusion (PBF) methods. A group of examples of PBF processes are the selective laser melting processes (SLM).

A second category of methods are the methods of the group of Directed Energy Deposition (DED) methods, in particular methods in which the material for the method is supplied in addition to the energy irradiation. One group of examples of DED processes are laser cladding processes.

The inhomogeneities resulting from the dynamics of the melt pool can be promoted, for example, by the fact that the energy density in the process is specifically reduced in comparison to the given specifications. This can happen, for example, by choosing the laser power too small, by choosing the scanning speed too high, and / or by choosing the distance between adjacent tracks (sometimes also called the 'hatch distance') too large.

[0023] The inhomogeneity can be formed by a porosity of the identification area material. This is characterized by a significantly lower material density than 100 percent. However, in addition or as an alternative, it can also relate to magnetic properties, crystallographic or molecular orientations and / or other properties.

In embodiments, the inhomogeneity that can be read out, which forms the coding, is present in the interior of the object provided with the identification area, for example a key, and can therefore neither be seen nor scanned from the outside.

For example, the inhomogeneity in the identification area produced by means of the DED method can be formed by the course of an interface, as arises when material is applied to an existing substrate. Such an interface can be between material applied by the process and the existing substrate. Such an interface is located inside the manufactured body and is therefore not visible or palpable from the outside.

Special embodiments of identification areas produced with the DED process include, for example, the connection of magnetizable and non-magnetizable weldable materials, the interface between magnetizable and non-magnetizable material is not flat and is characterized by a varying intermixing, so that the thickness of the layer produced by the process and the magnetic properties of both layers fluctuates as a function of the position along the surface.

For example, when the identification area is produced by means of a PBF method - or also in other embodiments - the identification area can be encompassed by homogeneous material. ("Homogeneous" here means a homogeneity in relation to the readable measured variable, for example to an eddy current sensor measurement; the homogeneity should be at least one order of magnitude higher than that of the identification area). For example, the identification area produced using the PBF method can be enclosed in a non-porous material.

In a group of embodiments, at least one manufacturing parameter is additionally varied in the additive manufacturing process according to the random principle. This can optionally be done in such a way that the variation can no longer be reproduced afterwards, for example in that a temporal correlation between the variation and the scanning process and / or between different variations depends on manually performed, non-recorded actions. Regardless of whether the variation of the at least one production parameter would theoretically be reproducible or not, this group of embodiments also provides complete copy protection. This is because it is not the result of the manufacturing process that is varied at random, but only the process that will always produce non-identical results due to fluctuations. The stochastic fluctuation of the at least one production parameter is therefore merely a support for the definition of the non-reproducible coding. However, by increasing the inhomogeneities, it can contribute to the robustness of the readout process. This can be of considerable advantage, especially in systems with authorization devices of different security levels, in which authorization devices of lower security levels are often designed in a simpler manner.

In particular, but not only, for applications for keys and key-based systems, the following also applies: <tb> <SEP> It is also an option with an arrangement of several identification areas (key parts) and / or with varied sizes and / or shapes at least one with an arrangement of several identification areas (key parts) that varies from object to object (i.e. from key to key) or from key group to key group Identification area to provide a second, deterministic coding. This can also only be difficult to copy, for example if the identification area (s) is / are not visible from the outside or cannot be felt.

In addition or as an alternative, a third coding in the form of a conventional mechanical and / or electronic coding of the type known from the prior art can also be present. In particular, such a further, third coding can be mechanically scanned and can be formed by bores, milling, magnets and / or movable elements.

A key of the type according to the invention can in particular be a key of a locking system and of conventional form with a key shaft - with the at least one identification area as the key part - and a key bow. It can then interact with a locking cylinder which is actuated by turning the key, with or without a release depending on the result of the reading. The key is read out, for example when it is inserted into the key channel, by a sensor arranged in its vicinity. It is also possible to provide a read-out process with corresponding, for example, two-dimensional resolution only after it has been inserted into the key channel.

A key body (for example key shank) with the key part can in particular have a shape that is not rotationally symmetrical about an axis (key axis). This has the advantage that the lock cylinder - provided with a correspondingly shaped key channel - can be rotated by turning the key, if the corresponding release is available. A particularly suitable shape is the shape of a flat key. The lock cylinder can then optionally be programmed so that the flat key can serve as a reversible key, i.e. the key works in two orientations that differ from each other by turning it through 180 °.

In an embodiment as a flat key, the identification area can be present on at least one flat side or, alternatively, on at least one back of the key, i.e. on one narrow side. The latter has the advantage of being easy to manufacture. In addition, a sensor of the reading device can easily be placed, for example, on a stator of the lock cylinder. In the case of combinations with mechanical coding, there is the further advantage that only little space is required on the key and therefore the number of possible mechanical permutations is only slightly limited compared to conventional mechanical keys.

As an alternative to a conventional form of mechanical key, the key according to the invention can also have any other shape, for example a card shape. When reading out, the key can then be held or guided in a defined position and orientation relative to the reading device. Alternatively, the orientation can also be determined in parallel to the read-out process and / or on the basis of the read-out data by data evaluation, in which case the user only has to position the key approximately as specified.

A metal, for example steel, is often preferred as the material of the identification area (i.e. in the application example the key of the key part) or possibly also of the entire key. Metallic materials - or generally electrically conductive materials - have the advantage that they are suitable for measurement using eddy current sensors. The approach according to the invention can, however, also be implemented, for example, with plastic or, quite generally, with all weldable materials. Measurement methods for measuring the properties of plastics, which for their part can have fluctuating properties, are known.

In addition to the key, the invention also relates to an identification system, for example a locking system. Such a device has an identification object, for example a key, and an identification device. The identification object has an identification area with a stochastic inhomogeneity produced using an additive manufacturing process. The identification device has a reading device and, for example, a data memory (it is also possible that the identification device does not have the data memory itself, but can access an external data memory; a non-localized storage solution (“cloud” solution) can also be used as the external data memory Question). A reference measurement of the identification area with the stochastic inhomogeneity is stored in the data memory, which serves as coding (the reference measurement can include a single measurement or a plurality of measurement runs followed by averaging or the like). The reading device is set up to measure the measured variable on the identification area, and the identification device is set up to compare the result of this measurement with the reference measurement in order to determine whether the identification object is identical to the object on which the reference measurement was made.

Such a comparison can, for example, in a manner known per se, include a quantification of a deviation between the measurement and the reference measurement, in which case the identity is concluded if the deviation is below a certain threshold value.

The measured variable that is recorded during the reference measurement and the measurement by the reading device is in particular an electromagnetic measured variable as a function of a position in the identification area. In this way, the reading process differentiates firstly from reading out mechanical codes, in which the measured variable is the geometry of the coded object - for example the course of spikes or the dimensioning of coding bores. Secondly, the reading process differs from reading out electronic codes, e.g. from RFID chips in which the measured variable is a signal from the corresponding chip in response to a stimulus in which no spatial resolution (no dependence on a position) is measured.

The electromagnetic measurement of the measurand is, in particular, a measurement that scans the material in a deeply effective manner, i.e. the measurement does not only capture properties of the surface and is also different from a purely optical measurement in this regard. In particular, the measurement can be an eddy current measurement or a magnetic inductive measurement, but also a conductivity measurement, etc.

Other methods of non-destructive testing of materials can also be used, for example acoustic measurements (resonance analyzes, ultrasound measurements, impact echo measurements, etc.). In particular, methods for non-destructive testing of materials can be used quite generally, which are based on an interaction with the volume of the material and not just with the surface.

Another difference to readout processes according to the prior art, as follows from the above statements, is that the result of the measurement carried out is not compared with a specification (e.g. a predetermined mechanical coding or a programmed code) but with a mandatory one necessary reference measurement.

[0042] The reading device can in particular contain an eddy current sensor. The structure and the measuring principle of eddy current sensors are known per se for material testing and are not the subject of the present invention. In principle, sensors for magnetic-inductive measurements can also be used for the reading device. The dependence on the position can be measured, for example, in that the reading device also has a position sensor in addition to the electromagnetic sensor (for example eddy current sensor). It can in particular be provided that the identification object (e.g. key) is guided along an axis for the reading process, that an electromechanical or other sensor detects the position along this axis, and the reading device correlates the electromagnetic signal with the position information.

Sensors for detecting properties other than porosity or magnetic properties are also not excluded, for example for detecting stresses, material distribution, microstructure (crystal size, crystal orientation), nuclear spin, etc.

In embodiments, the identification system is a locking system in which the object of identification is a key and the identification device is designed as an authorization device (for example a lock device, in particular a lock cylinder). As part of the authorization device, the corresponding key-based identification system has a reading device which is equipped and set up to read out the coding. The locking system can in particular contain several non-identical keys, which may have been produced under identical conditions.

The identification device (s) of the system is / are provided with or can be connected to a data memory in which the results of a read-out process on one or more identified, for example justified, identification object (s) are stored. The results of the readout process can be saved directly, immediately or processed further. This includes the possibility that the results are saved in the form of a hash value, i.e. the stored values do not have to represent the entire result of the readout process; a comparison with the results of a new readout process carried out for the purpose of checking the authorization is sufficient.

To read out the identification information, the reading device can contain a sensor or, for example, a one-dimensional arrangement of sensors that spans the entire width of the identification area (or the identification areas) and past which the identification object is moved relative to the sensors for the readout process. For this purpose, the reading device also records information about the path by which the identification object is moved relative to the sensor or to the sensors in order to obtain the aforementioned dependency on the position and thus a one-dimensional or two-dimensional signal.

The reading device can optionally be set up to evaluate such a path signal in order to recognize whether the identification object is being moved (e.g. pushed in) by a person and e.g. to prevent the system from being blocked by a synthetically generated signal or by feeding in a earlier measurement can be outwitted.

Instead of a one-dimensional arrangement of sensors, a two-dimensional arrangement of sensors is also conceivable for a measurement on an identification object that is stationary relative to the sensors. With sufficiently small sensor elements, such a measurement is also conceivable with a one-dimensional sensor arrangement or the like.

Another optional safety measure is the use of several sensors of the same or different types, with the correlation of the signals also being evaluated. For a manipulation, not only would the sensor signals from different sensors have to be simulated, but also their synchronicity.

A method for providing a key comprises producing the key, at least one identification area being produced as a key part with an additive production process and thus being provided with a (first) coding forming stochastic inhomogeneity, as explained above. The method can also include reading out the coding and storing the result of the reading process. This can be done by the key manufacturer or - in compliance with suitable security measures - by the user, for example immediately using the authorization device. The corresponding result is then stored in the data memory available to the authorization device and can be called up from there for checking the authorization.

The invention also relates to the use of an area of a material body, for example a key, produced with an additive manufacturing process and having a stochastic inhomogeneity as an individually coded identification area. The material body, for example a key, can have properties of a key of the type described in this text and defined in the claims, and / or the material body can be produced using a method of the type described in this text for key production and defined in the claims .

It can be used in an identification system of the type described in this text and defined in the claims.

In the following, the subject matter of the invention is explained in more detail using exemplary embodiments and the accompanying drawings. In the drawings, the same reference symbols denote the same or analogous elements. The drawings are schematic and not to scale. Show it: <tb> Fig. 1 <SEP> A view of a key; <tb> Fig. 2 <SEP> is a front view of a lock cylinder; <tb> Fig. 3 <SEP> another key; <tb> Fig. 4 <SEP> the scan principle used for the SLM process; <tb> Fig. 5 <SEP> the relative density in comparison with a reference density of the material of a body manufactured using the SLM process as a function of the energy density; <tb> Fig. 6 <SEP> a key body with several key parts; <tb> Fig. 7 <SEP> a variant of a key body with second and third coding; <tb> Fig. 8 <SEP> a readout process; <tb> Fig. 9 <SEP> the mode of operation of the DED process; <tb> Fig. 10 <SEP> the course of an interface after application of the DED method; <tb> Fig. 11 <SEP> a systematic variation of the laser power as a manufacturing parameter; <tb> Fig. 12 <SEP> the result of an eddy current measurement on a sample produced with the DED process; <tb> Fig. 13 <SEP> a variant of a key; <tb> Fig. 14 <SEP> a front view of a lock cylinder for a key according to FIG. 13; and <tb> Fig. 15 <SEP> an object different from a key with an identification area.

Some parts that are not essential for understanding the invention are not shown. The exemplary embodiments described are examples of the subject matter of the invention or serve to explain it and have no restrictive effect.

Figure 1 shows schematically a key 1. This can have a shape similar to a mechanical key of the known type, with a key head 2 and a key shaft 3, which has the coding. In the exemplary embodiment shown, the key shaft 3 is not rotationally symmetrical in cross section perpendicular to a key axis 10, but essentially rectangular, so that the key can be referred to as a flat key. Due to the lack of rotational symmetry about the key axis 10, the key 1 inserted into a lock cylinder 11 (FIG. 2) with a correspondingly shaped key channel 12 can rotate a rotor 13 of the lock cylinder relative to a stator 14 in order, for example, to unlock a door lock, if, depending on If there is authorization, a rotation of the rotor 13 relative to the stator 14 is enabled and / or the rotor is coupled to an output unit of the lock. A key part, for example the key shaft or an area of the key shaft, is manufactured using an additive manufacturing process, and the resulting inhomogeneities serve as the identification information, i.e. the key information (optionally together with other, for example conventional, codes).

Other key shapes are also possible. Figure 3 shows a key 1 in the form of a chip card with an area 4 produced in accordance with the teaching of the present invention, possibly together with a conventional chip 5, which can also contain part of the key information. Many other forms are conceivable, with or without the optional property of the embodiment of FIG. 1 that the key can be used to grip a lock cylinder in order to rotate its rotor in the stator.

Additive manufacturing processes are known per se. Mostly they are based on the principle that a heat source, e.g. in the form of one or more laser beams, an arc or possibly another beam, e.g. an electron beam, creates a local melt pool in a material, which causes the material properties to change locally. In what is known as selective laser melting (SLM), this means that a material originally in powder form in an approximately homogeneous powder bed melts locally at the location of the weld pool, so that a solid material structure is created after solidification. The object to be manufactured is built up track by track and layer by layer. The principle is illustrated schematically in FIG. 4, in which reference numeral 21 designates a track that is produced when the vehicle is passed in the scanning direction 22. By switching the energy source on and off while scanning, desired structures can be created.

4 shows a variant in which the tracks of successive layers in the structure of the object run straight and parallel to one another and the tracks of successive layers are perpendicular to one another. It is not necessary. The tracks of successive layers can also be parallel or at a non-perpendicular angle relative to one another. Non-straight courses, for example with concentric circles, etc., are also easily possible.

Additive manufacturing processes of the known type are usually aimed at producing a structure that is as homogeneous as possible. This can work better or less well depending on the perfection achieved. The present invention is characterized in that inhomogeneities that arise in contrast thereto are used and, for example, the method is carried out in a targeted manner in such a way that more inhomogeneities arise than would be the case if attention were paid to the greatest possible homogeneity.

In the SLM method, this can be done, for example, by choosing the energy density. The energy density E is: E = Plaser / (vscan * h * t), where Plaser is the laser power, vscand is the scanning speed, t is the layer thickness and h is the so-called hatch distance, i.e. the distance between two adjacent tracks (see Fig. 4). Figure 5 shows in the graph in the upper area schematically the dependence of the density ρ of a body produced with SLM on the energy density E used during the process. The value 1 for the density ρ stands for the theoretically maximum possible density with the material in question, corresponding to a perfectly homogeneous structure ie ρ is the density of the produced body normalized with the physical density of the selected material. If the energy density is sufficiently small, the density defined in this way is markedly smaller than 1. The reason for this is that pores are formed due to the imperfections, as can be seen very clearly in the - real - sectional images in the lower area of FIG. These relate to a sample made with the material 1.2709 tool steel, with an energy density of 58.0 J / mm <3> being used in the sectional image on the left, which led to a density of 98.78% of the reference density (density of homogeneous 1.2709 tool steel), while in An energy density of 116.0J / mm 3 was used and the resulting density was 99.82%.

In embodiments of the invention, the energy density is chosen so that the density ρ in the key part is markedly lower than the actual maximum achievable. In particular, the energy density can be selected so that the value (1-p) is at least twice as high as the maximum achievable with the additive manufacturing process used. In particular, the density ρ is, for example, less than 99%, for example less than 98.5%. The key part is given a porosity that is correspondingly higher than the achievable minimum.

FIG. 6 shows a key body 40 with a plurality of key parts 41. The key body can, for example, form a key shank or a region thereof, or in the embodiment of FIG. 3 region 4 or a part thereof. The key parts 41 are arranged inside the key body 40 and are not visible from the outside. Those parts of the key body 40 which are not key parts can, for example, also be produced using the additive manufacturing process, but be produced without increased porosity, i.e. with manufacturing parameters that are optimized for the most homogeneous possible material quality.

FIG. 7 illustrates the option of effecting an additional, deterministic coding with the arrangement and / or the shape of the key parts. In comparison to FIG. 6, key parts 41 are not present in all positions where this would be possible. The shape of the key parts can also be varied in a targeted manner, as illustrated in FIG. 7, in that the key part 41 at the rear left has a different shape than the other key parts. The arrangement and / or shape can be selected during manufacture and form a second code. This is deterministic, i.e. theoretically it can be copied. Especially when the key parts 41 are present inside the key body 40 as illustrated and are not visible from the outside, the second coding can only be copied with the knowledge of the key manufacturer or with considerable effort. In a locking system, the first coding (non-deterministic, due to the inhomogeneities resulting from the additive manufacturing process) and possibly the second coding can be used in a targeted manner. For example, readers can read out only the second code in less security-relevant areas - for which they can possibly be designed more simply and which enables access using a whole group of apparently identical keys - and in security-relevant areas both codes, which can only be accessed through registered, individual keys possible.

Also shown schematically in FIG. 7 is the possibility — which exists independently of the second coding — to additionally provide a third, conventional coding. In Fig. 7 this is illustrated by a coding hole 44; In reality, of course, mechanical and / or electronic coding of greater complexity can be present, for which there are means known per se from the prior art.

The key information is read out firstly when the key is initialized in a dedicated device provided for this purpose or in a lock device that is activated accordingly. Later, the reading is carried out by the lock device for each authorization check. FIG. 8 schematically illustrates a reading process in a device set up for this purpose. In the embodiment of FIG. 2, such a device or a part thereof can be built into the lock cylinder. The key body 40 with the at least one key section 41 is guided past an eddy current sensor (for example with a row of eddy current sensor elements, each with a coil) 51. This forwards the recorded signal to an evaluation unit 52, in which the signal is recorded and evaluated. During the initialization, the evaluation includes the storage of features of the coding and, during an authorization check, includes the comparison with stored data on authorized keys during an authorization check. For example, the stored data of the reference measurement can simply contain a signal - for example from the eddy current sensor as a function of the position, and the authorization check can contain a direct comparison of this data with the measured values. However, it is also possible to compare processed data, for example hash values. Evaluation methods for comparing direct measured values or processed values are known per se. 8 also shows schematically an interface 53 via which the evaluation unit can communicate with further components, for example by activating an electromechanical unlocking device or by passing on the information about the presence of an authorization to another device in a secured manner.

In the embodiment shown above, the additive manufacturing process was an SLM process, and the manufacturing parameters were specifically chosen so that the result of the manufacturing has more inhomogeneities / defects than in the case of manufacturing under ideal parameters. Neither is necessary. If the resolution of the readout device is sufficiently high, depending on the manufacturing parameters - for example, the grain size of the powder used in the SLM process - those inhomogeneities which cannot be avoided even with ideally set manufacturing parameters can be sufficient.

In addition, additive manufacturing processes other than the SLM process come into question. FIG. 9 schematically illustrates an embodiment of the Directed Energy Deposition (DED) process. The DED process, which is also part of the additive manufacturing process, is based on a principle similar to the SLM process and differs from it in that the material to be processed - e.g. Metal in powder form - is not present in the form of a homogeneous material bed, but is supplied directly, e.g. in the form of a powder blown locally to the point of impact of the laser beam representing the heat source on a substrate or by supplying a wire, etc.

9 accordingly illustrates an embodiment of the DED method in which a second metallic material (optionally identical to the first material) is applied to the surface of a substrate 60 made of a first metallic material. This can be in the form of a wire or a foil or similar, or as shown in FIG. 9 in the form of a powder jet 62. Electromagnetic radiation, for example in the form of a focused laser beam 61, is applied to the surface with the applied second material, for example selectively irradiated in order to locally generate a molten pool 63 from the second material and the surface of the first material, so that a melt-metallurgical bond is formed. The result is a coating 64 of the substrate which consists of the second material and - at least in a border area to the substrate - portions of the first material.

An interface 65 between the area of the substrate, which remains solid during the process, and the coating can run in the product at different depths depending on the radiated energy (FIG. 10). The coating material mixes locally and in different ways with the melted substrate in the boundary area 66. Fluctuations during the process as well as naturally existing inhomogeneities in the material of the substrate (e.g. grain boundaries or similar) and the applied material cause fluctuations in the depth 68, the material distribution and the material structure of both layers. As a result of the heat introduced, the structure of the non-melted substrate is also locally changed, which leads to the formation of a heat-affected zone 67. The fluctuations mentioned form inhomogeneities which can be read out by a readout process - for example also by an eddy current sensor. In addition to or as an alternative to the mentioned depth 68, fluctuations in magnetic properties can also serve as inhomogeneities if the first and / or the second material is magnetizable. Fluctuations in magnetic properties can also be measured by an eddy current sensor.

Similar to the example of SLM, the process can also be carried out in a targeted manner during production by the DED process in such a way that the inhomogeneities are promoted. In addition to a choice of the production parameters in a range that is not ideal for homogeneous properties - such a choice is also possible for the DED process; in particular if the second material is in powder form, this will lead to increased porosity, similar to the SLM process - a randomized fluctuation of at least one production parameter is also possible in both processes. Possible manufacturing parameters are the laser power P, the feed rate v, the beam diameter s, the hatch distance h and the powder feed rate mt. A randomized variation of P and / or v is particularly easy to implement. FIG. 11 schematically shows an example of a laser power that is randomly changed over time, which varies here by a factor of 2. 11 shows the power as a function of time in any units (aU). The average power by which the current power value fluctuates can be selected, as is known per se for the selected method on the selected material, or, for example, be slightly higher or slightly lower .

Example: A coating is produced on a cuboid substrate made of structural steel by means of DED technology with the addition of powder made of chromium-nickel steel, the laser power (a disk laser with λ = 1070 nm wavelength) according to FIG. 11 being between 500 W and 1150 W is varied and at the same time the feed per track is changed between 700 and 900 mm / min. The distance (hatch distance) between adjacent tracks is 0.85 mm. The resulting product is measured using the eddy current technique, with eddy current signal strength S being recorded as a function of the position along the coating plane (x, y plane). Figure 12 shows the result of the readout process. The signal strength S of the eddy current measurement is shown as a function of the position x, y along the coating plane.

FIG. 13 illustrates a key in which the key section 41 is not attached along the flat side of the key shaft, but on its back. On the one hand, this has the advantage that the flat sides and / or for mechanical coding remain free. The same applies if only one of the backs is provided with the key section, for the opposite back, for example for key points. On the other hand, there is the advantage that, as illustrated in FIG. 14, the sensor 51 of the reading device can be accommodated in the stator 14 of the lock cylinder, which is why it remains static when the lock cylinder is actuated, which simplifies its contacting.

For a reversible key system with, for example, a sensor arrangement as shown in FIG. 14, it can also be provided that both key backs are each provided with a key part 41, and that a reference measurement is made with both of these key parts so that the key is independent from this it is recognized in which of two possible orientations the key is inserted.

The exemplary embodiments described above relate to the application example “key / key-based system”. However, the principles described can also be applied to other systems.

FIG. 15 accordingly illustrates an identification object 101 for implementing the principle according to the invention for applications other than locking systems. The identification object 101 is, for example, an object of any shape and function that is manufactured at least partially with an additive manufacturing process. For traceability, it is provided with an identification area 141 of the type described here, in which the production parameters are selected such that stochastic inhomogeneities result. The manufacturer takes a reference measurement before the item is shipped. Later, by reading out the coding, which is formed at least partially by the stochastic inhomogeneities, it can be checked at any time in a tamper-proof manner whether or not an object 101 corresponds to the original object supplied by the manufacturer and provided with guarantees, for example. Due to the approach according to the invention, the identification area 141 cannot be copied.

Claims (29)

1. Key (1), having an individual coding which can be read out by an authorization device and by means of which the authorization of the key can be checked, characterized in that an identification area (4, 41) of the key is produced by an additive manufacturing process and the coding is formed by a stochastic inhomogeneity that results from the additive manufacturing process. 2. Key according to claim 1, wherein the inhomogeneity in the interior of a key body (40) is present and cannot be seen or felt from the outside. 3. Key according to claim 1 or 2, wherein the inhomogeneity includes a porosity or a local change in magnetic properties. 4. The key according to claim 3, wherein the identification area which forms the porosity is encompassed by non-porous material. 5. Key according to one of the preceding claims, wherein the inhomogeneity is at least partially formed by a non-planar interface between two layers with different properties. 6. Key according to one of the preceding claims, comprising a key bow and a key shaft, wherein the key shaft has the identification area. 7. Key according to one of the preceding claims, designed as a flat key in that the key shaft is flat and forms two flat sides and two narrow sides parallel to a key axis, the identification area (41) being arranged on one of the narrow sides or both narrow sides. 8. Key according to one of the preceding claims, having a plurality of identification areas (41), the arrangement of which forms a second coding. 9. Key according to one of the preceding claims, having a further coding (44) which can be mechanically scanned. 10. Key according to claim 9, wherein the further coding is formed by at least one bore, milling, a magnet and / or a movable element. 11. Key according to one of the preceding claims, wherein the coding formed by the stochastic inhomogeneity can be read out by an electromagnetic sensor (51) as a function of the position in the identification area. 12. Key according to one of the preceding claims, wherein the stochastic inhomogeneities are mesoscopic and / or macroscopic. 13. Key according to one of the preceding claims, wherein the stochastic inhomogeneities are formed by pores and / or the arrangement of areas with different materials. 14. The key of claim 13, wherein the different materials include at least one magnetic and at least one non-magnetic material. 15. Identification system, comprising an identification object (1, 101) and an identification device (11), the identification object (1, 101) having an identification area (4, 41, 141) with a stochastic inhomogeneity produced using an additive manufacturing process, the identification device has a reading device and is set up and set up for access to a data memory, wherein the reading device is set up to perform a measurement of a measured variable dependent on the stochastic inhomogeneity on the identification area and the identification device is set up to compare the result of this measurement with a measurement available via the data memory Compare reference measurement to determine whether the identification object is identical to an object on which the reference measurement was made. 16. Identification system according to claim 15, designed as a locking system, in which the identification object is a key according to one of claims 1-14, in which the stochastic inhomogeneity forms the coding. 17. Identification system according to claim 15 or 16, wherein the measured variable is an electromagnetic measured variable. 18. Identification system according to claim 17, wherein the measured variable is an electromagnetic measured variable as a function of a position in the identification area. 19. Identification system according to claim 18, wherein the reading device includes a displacement and / or position sensor for determining a movement and / or position of the identification object relative to a sensor of the reading device. 20. Identification system according to one of claims 17-19, wherein the reading device includes an eddy current sensor (51). 21. A method for creating a key with an individual coding, which can be read out by an authorization device and by means of which authorization of the key can be checked, the identification area being produced by an additive manufacturing process and being provided with a stochastic inhomogeneity. 22. The method according to claim 21, wherein the additive manufacturing process includes the local heating of material by means of at least one energy source (61) and the displacement of the energy source relative to the material, and wherein the energy density is selected to be lower than necessary for a homogeneous material structure. 23. The method according to claim 22, wherein the additive manufacturing process, in addition to the identification area (4, 41), produces further areas of a key body (40) using the additive manufacturing process, and wherein the energy density when producing the further areas is higher than when producing the identification area . 24. The method according to any one of claims 21-23, wherein the additive manufacturing process is a powder bed fusion (PBF) process, in particular a selective laser melting process (SLM). 25. The method according to any one of claims 21-23, wherein the additive manufacturing method is a Directed Energy Deposition (DED) method. 26. The method according to any one of claims 21-25, wherein in addition at least one manufacturing parameter is varied according to the random principle in the additive manufacturing process. 27. The method according to any one of claims 21-26, comprising an initialization step after the production of the identification area, wherein the individualization step includes reading, for example by means of eddy current measurement, the coding and storing a result of the reading in a data memory available to the authorization device. 28. Use of an area of a material body produced with an additive manufacturing process and exhibiting a stochastic inhomogeneity as an individually coded identification area for identifying the material body, the inhomogeneity of the identification area being recorded in an initial reference measurement and the result of the reference measurement being stored, and for identifying the material body a measurement of the inhomogeneity is carried out and compared with the result of the reference measurement. 29. Use according to claim 28, wherein the material body is used as a key and the identification is carried out by an authorization device for the purpose of checking the authorization of the key.