Optimized blade production method

Abstract

The invention relates to a method for producing a blade (10) from a steel strand (12), which is defined along a longitudinal extension axis (L), a transverse axis (Q), and a depth axis (T). The steel strand (12) has a front end (14), a rear end (16), and two parallel steel strand longitudinal edges (18a, 18b), each of which extends from the front end (14) to the rear end (16). The method has at least the following steps: First, a blade grid is physically embossed into the steel strand (12) such that the steel strand (12) has one or more embossments (20), the blade grid mapping a plurality of blades (10). Subsequently, the one or more embossments (20) are partially hardened. The steel strand (12) is then loaded so as to break along at least one of the partially hardened embossments (20). Finally, at least one blade (10) is released from the steel strand (12), the at least one partially hardened embossment (20) forming a blade outer edge.

Description

[0001] LD 44685 / WK - 1 - December 2025

[0002] Optimized blade manufacturing process

[0003] Technical field

[0004] The following descriptions concern a method for manufacturing a blade from a strand of steel.

[0005] The following remarks also concern a blade manufactured using such a method.

[0006] Technical background

[0007] It is well known that blades are used in a wide variety of industrial and craft applications, such as cutting tools or machine cutting systems. Such blades are typically manufactured from steel strands. These steel strands are often supplied in coil form, which are then heat-treated and machined to produce the required blades.

[0008] The current state of the art involves first hardening steel strands and then tempering them after the blades have been separated. A key aspect of such processes is maintaining the entire steel strand at an increased hardness to allow the blades to be separated from the strand via brittle fracture. However, this increased hardness results in the blades being too brittle and too hard for certain subsequent applications after separation. To compensate for these disadvantages, tempering is required as a subsequent heat treatment. Dividing the hardening and tempering of the entire steel strand into individual steps is time-consuming and significantly increases production costs. LD 44685 / WK - 2 - December 2025

[0009] There is therefore a need for an improved process that overcomes the existing disadvantages. Based on this need, the present task is to propose a process for manufacturing a blade, as well as the blade itself, while increasing manufacturing efficiency.

[0010] Description - Technical Solution

[0011] The present problem is solved by the features of the independent claim. Advantageous embodiments are specified in the dependent claims, the description, and the drawings. Where technically feasible, the teachings of the dependent claims can be combined arbitrarily with those of the main and dependent claims.

[0012] In particular, the problem is solved by a method for manufacturing a blade from a steel strand having a longitudinal axis, a transverse axis and a depth axis, wherein the steel strand has a front end and a rear end along the longitudinal axis, wherein the steel strand has outer steel strand edges with two parallel steel strand longitudinal edges, each extending from the front end to the rear end.The process comprises at least the following steps: physically imprinting a blade grid into the steel strand, such that the steel strand has one or more imprints, wherein the blade grid represents a plurality of blades, in particular successive blades along the longitudinal axis and / or transverse axis; partially hardening one or more imprints; subjecting the steel strand to stress such that the steel strand breaks along at least one partially hardened imprint; and releasing at least one blade from the steel strand, wherein the at least one partially hardened imprint forms a blade outer edge.

[0013] In other words, the process involves the precise imprinting of

[0014] Blade patterns are inserted into a steel strand and their targeted hardening for subsequent controlled blade release (LD 44685 / WK - 3 - December 2025). Controlled fracturing along the hardened areas enables the efficient release of blades with defined outer edges without the need for extensive subsequent heat treatment. Conventional steel strands regularly have the problem that, for blade singulation, they must be harder than the final blade can be to allow for brittle fracture. After blade singulation, i.e., the release of the blades, they must be heat-treated to the actual target hardness. For this purpose, they are usually tempered.Only the fundamental concept presented here—hardening only the fracture edges formed by the indentations, i.e., partially hardening the steel strand—allows the steel strand to be brought close to its target hardness at an early stage and the desired ductility to be introduced early on. Thus, an alternative blade manufacturing method to the state of the art is proposed.

[0015] The following sections explain advantageous aspects and subsequently describe preferred modified embodiments. Explanations, particularly regarding advantages and definitions of features, are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be explicitly stated.

[0016] It is preferred that the sequence of process steps can be varied, unless a specific sequence is technically required. However, the aforementioned sequence of process steps is particularly preferred. For example, the steel extrusion external edge grinding or steel extrusion longitudinal edge grinding described below can be performed before or after almost any process step. The sequence of physical impressioning, partial hardening, and loading for blade release is important, however.

[0017] Partial hardening is preferably carried out thermally, in particular by a microstructural transformation, so that it can also be referred to as thermopartial hardening. LD 44685 / WK - 4 - December 2025

[0018] Where ordinal numbers, such as "first," "second," etc., are used, for example to designate a steel strand's longitudinal edge, these ordinal numbers are solely for differentiation in the designation and do not indicate any dependencies or sequences. This means, in particular, that a blade or a steel strand does not need to have a "first steel strand's longitudinal edge" to have a "second steel strand's longitudinal edge." A blade or a steel strand can also have a "first steel strand's longitudinal edge" as well as a "third steel strand's longitudinal edge" without necessarily having a "second steel strand's longitudinal edge." Multiple units of the same ordinal number can also be used, for example, multiple "first steel strand's longitudinal edges."

[0019] In particular, the steel strand is formed as a coil. A coil can be an industrially manufactured, rolled-up metal strip, often made of materials such as steel or stainless steel, and is preferred due to its efficient storage, transportability, and ease of further processing. In the present blade manufacturing process, a coil serves as the preferred starting material from which blade blanks are produced. To expose the steel strand, the coil is first unwound on special machines. This unwound material then forms the steel strand in question. A coil is essentially cylindrical, consisting of a cylindrical surface and two end faces.

[0020] In particular, the blade is a cutting blade, for example a machine cutting blade, preferably with a recess, and more preferably with an elongated hole. The blade can be ground on at least one or two edges. However, it is also possible that the blade is not ground. For example, instead of the triangular shape typical of cutting blades, the blade can then have a rectangular shape with right angles in that area. LD 44685 / WK - 5 - December 2025

[0021] The blade can be ground on one or both sides, with the grinding particularly possible along the longitudinal axis and / or along the transverse axis. It can be a blade made of an alloy or a bi- or tri-metal, i.e., a blade consisting of a base body and one or more attached elements, particularly high-speed steel (HSS). In this context, bi-metal means, in particular, that an HSS wire or strand is attached to the outside of a steel strand and flattened. Tri-metal is essentially an extended bi-metal, in which an HSS wire or strand is attached to the outside of two steel strands and flattened, so that the blade can then have two cutting edges.Bi- and trimetals can have the advantage of forming cutting edges from a harder material that stays sharp longer, while the base body can have more ductile properties and better compensate for impact loads without damaging or even destroying the blade.

[0022] Examples of blades include, but are not limited to: Trapezoidal blade: A trapezoidal blade, often used in utility knives. It may be sharpened on one or both edges and often has a slotted hole for attachment.

[0023] Industrial blade / machine cutting blade: Blades for industrial applications that meet high demands for durability and cutting performance. They can have various shapes and grinds.

[0024] Snap-off blade: A blade with segmented sections that can be snapped off one after the other to ensure a consistently sharp cutting edge. It is usually sharpened on one side only.

[0025] Graphic blade: Fine blades for precise cutting work, for example in the graphic design or model making industries. They often have a pointed shape for detailed cuts.

[0026] Styrofoam blade: Specially designed for cutting materials like Styrofoam, often with special grinds or shapes to ensure clean cuts. LD 44685 / WK - 6 - December 2025

[0027] Hook blade: Blades with a hook-shaped cutting edge, ideal for cutting carpets, foils or roofing felt without damaging the underlying material.

[0028] Bow blade: Blades with a special bow shape for specific cutting tasks, for example in the packaging industry or in film work.

[0029] Pointed blade: Blades with a pointed cutting edge for precise and fine cuts, frequently used in crafts and art.

[0030] Scalpel blade: Very sharp blades for medical or precision applications requiring the highest level of accuracy.

[0031] Scraper blade: Blades used to remove coatings or contaminants from surfaces, often with a blunter cutting edge.

[0032] Longitudinal axis, transverse axis and depth axis

[0033] In particular, the longitudinal axis, the transverse axis, and the depth axis are perpendicular to each other, as in a Cartesian coordinate system. The longitudinal axis runs along the longitudinal axis of the unwound steel strand. The transverse axis runs along the width of the steel strand; in other words, using the example of a steel strand wound into a coil, the transverse axis is oriented parallel to the axis of rotation of the coil. The depth axis runs along the thickness of the resulting blade; in other words, using the example of a steel strand wound into a coil, the depth axis is oriented radially to the coil. The axes are considered below, particularly with reference to an unwound steel strand.

[0034] The end of the coil is specifically the end that, in the case of a steel strand wound into a coil, forms the outer free end of the strand. When the coil is unwound, the end of the coil is the first exposed end and is preferably used as the starting point for processing steps such as stamping, partial hardening, loading, and / or release. LD 44685 / WK - 7 - December 2025

[0035] The rear end is specifically the end that, in the case of a steel strand wound into a coil, forms the inner free end of the steel strand, i.e., near the axis of rotation of the coil. It represents the final end of the unwound steel strand and marks the end of the steel strand available for blade production.

[0036] The outer edges of a steel strand, particularly when considering a coiled steel strand, are all four outer edges of the strand. These include the two longitudinal edges, as well as the front and rear ends. They define the outer boundaries of the steel strand and can be relevant, for example, for processes such as attaching HSS wire to bimetallic or trimetallic blades. When one or more blades are released, the front end moves towards the rear end, and the two longitudinal edges of the steel strand shorten accordingly by the length of the released blades.

[0037] The longitudinal edges of the steel strand are part of its outer edges and extend parallel to each other from the front end to the rear end of the strand. Using the example of a steel strand wound into a coil, these are the two edges that form the lateral boundaries when unwound. In other words, the two longitudinal edges of the steel strand form the end faces visible when looking at one of the two end faces of a steel strand wound into a coil.

[0038] The physical imprinting is carried out along one or more intended fracture edges in the steel strand. It can be performed using state-of-the-art methods, for example, by punching with punching elements. An imprint can be made on one or both sides of the steel strand. In particular, the length of an imprint can extend over the entire desired fracture edge or only partially over it. In the case of partial extension, the imprint can be executed as a dashed line or taper off towards one or both outer ends of the desired fracture edge, for example, towards one or both future blade edges.

[0039] The depth of an indentation can be at least 0.1 millimeters, preferably at least 0.2 millimeters, and particularly preferably at least 0.5 millimeters. It can be at most 0.7 millimeters, preferably at most 0.5 millimeters, and particularly preferably at most 0.4 millimeters.

[0040] The width of an indentation can be at least 0.1 millimeters, preferably at least 0.2 millimeters, and particularly preferably at least 0.5 millimeters. It can be at most 0.7 millimeters, preferably at most 0.5 millimeters, and particularly preferably at most 0.4 millimeters.

[0041] However, other values ​​are also possible; all of the aforementioned values ​​can vary. Furthermore, this specifically includes values ​​that deviate from the aforementioned values ​​by no more than 10 percent, including any percentage difference.

[0042] The blade grid or blade pattern can consist of blades that follow directly one another, as with snap-off blades, or it can contain residual material. This residual material can follow each blade or be present between two blades, for example, when trapezoidal blades are embossed with a blade grid. Alternatively, several blades can follow directly one another, followed by residual material, as with snap-off blades. It is also possible that no residual material is present at all. Any residual material can either be disposed of directly or recycled, as can be the case with trapezoidal blades. The trapezoidal blades are self-locking during subsequent use.Alternatively, the remaining material can also be used to hold the blade material, for example in snap-off blades, where the individual blades, as is the nature of the snap-off blade, must not be fixed, as they must be snappable once they have become dull, for example.

[0043] The blade grid can be designed such that the blades follow one another along the longitudinal axis and / or the transverse axis. The aim here is to utilize the available steel strand as economically as possible, depending on the desired blades, and to minimize the amount of residual material.

[0044] If an execution is made for one or more impressions, then, in the sense of all the present explanations, it is meant that this can apply to just one impression, to a multitude of impressions, or even to every impression.

[0045] Partial hardening allows for the hardening of only the area along the indentations, rather than the entire steel strand. Specifically, a precisely selected area around each indentation is partially hardened, for example, including seven millimeters around each indentation, preferably including five millimeters, particularly preferably including three millimeters, and most preferably including two millimeters. Deviations of up to 10 percent of the respective value are specifically included.

[0046] It is preferable to ensure that the steel strand is through-hardened under an indentation or between two indentations, i.e., along the entire material thickness along the depth axis. Partial hardening can be performed on one or both sides of the steel strand and applies to one indentation, a multitude of indentations, or every indentation.

[0047] In particular, within the scope of this disclosure, the term partial hardening explicitly refers to a thermal heat treatment that results in a

[0048] Microstructural transformation, for example to the formation of martensite, is involved. It is preferred that partial hardening be distinguished from the physical imprinting step in terms of process engineering (LD 44685 / WK - 10 - December 2025). Pure work hardening, which can occur as a side effect of mechanical imprinting or stamping, is not partial hardening. Therefore, partial hardening is preferably used to selectively generate a hardness, and thus brittleness, locally in the imprinted area that is significantly higher than the hardness that could be achieved by mere work hardening, in order to ensure a defined brittle fracture in an otherwise tough base material. In particular, the term partial hardening can be equated with or replaced by the term thermopartial hardening in this context.

[0049] One result of partial hardening is that the steel strand exhibits different hardness zones, with areas of increased hardness being used to induce fracture and release the blade after appropriate stress testing. After release, tempering may be unnecessary, as the steel strand can already possess the target blade hardness, at least approximately, and preferably completely.

[0050] In partial hardening using laser radiation, a laser beam with precisely controlled power and focus is directed onto the areas of the indentations to be hardened, as described in the following example, though this is not the limiting factor. The high energy density of the laser beam heats the material locally above its critical temperature, initiating a martensitic transformation in the heated area. Rapid self-quenching against the surrounding, cooler material zone causes the heated area to cool quickly, resulting in hardening. This method offers the advantage that the laser radiation can be positioned very precisely, allowing for exact control of the hardened zones. Due to the localized heating, surrounding areas are hardly affected, thus minimizing deformation. Since no physical contact is required, tool wear is avoided.Furthermore, laser hardening is particularly suitable for applications requiring the highest precision and quality of the hardened areas. LD 44685 / WK - 11 - December 2025.

[0051] In partial hardening using induction hardening, an alternating magnetic field is generated to induce eddy currents in the areas of the indentations to be hardened, as described in the following example, though not limited to this description. Due to the electrical resistance of the material, these eddy currents cause rapid and localized heating above the critical temperature. Once the desired temperature is reached, the induction is stopped, and the heated area cools either in air or by controlled quenching, resulting in hardening. Induction hardening enables rapid heating and short process times, with the hardening depth being precisely controlled by adjusting the frequency, duration, and / or power.

[0052] Primarily, the aforementioned uniform heat treatment reduces the risk of deformation or material defects and improves reproducibility, making it ideal for high-volume series production. These hardening processes improve the quality of the fracture edges, resulting in more durable and higher-performing blades with reduced manufacturing requirements. The choice between laser radiation and induction hardening can be made depending on the specific requirements and conditions of production.

[0053] The steel strand is loaded in such a way that it breaks or buckles along at least one partially hardened indentation. This loading can be achieved, for example, with a support system that, in single or multiple configurations, has a support point, a support line, or a support surface as the origin of the load.

[0054] The abutment system can be designed so that only one blade is loaded at a time, or a single load application can enable multiple blade releases. The loading process itself is already known from classic blade manufacturing methods, although these typically involve fully or uniformly hardened steel strands, i.e., steel strands that are not partially hardened. LD 44685 / WK - 12 - December 2025

[0055] A potential risk with fully hardened steel strands is that the increased hardness or brittleness can lead to damage to the steel strand and / or blade breakage outside the intended blade grid. By subjecting only partially hardened steel strands to stress, scrap can be reduced.

[0056] The release of at least one blade from the steel strand is closely related to, or directly results from, the stress placed on the steel strand, for example, by bending the blade. The partially hardened indentation then forms an outer edge of the blade. This is preferably the final outer edge of the blade. However, it is also possible that this blade will be broken again, so that a new outer edge of the blade will form.

[0057] The process of releasing the blade is already known from classic blade manufacturing methods, which, however, involve releasing blades from steel strands that have been fully or uniformly hardened to their fracture hardness, i.e., from steel strands that are not partially hardened. The released blade can already possess the target hardness, unlike conventional blade manufacturing methods where, after singulation, a heat treatment process, particularly tempering, which significantly alters the material structure and is energy-intensive, is regularly required.

[0058] In principle, blade sharpening can be performed at any time, following state-of-the-art techniques. Preferably, the blade is sharpened before being subjected to stress, i.e., while still on the steel strand, to reduce the risk of injury, as a steel strand is easier and safer to handle than smaller blades.

[0059] Alternatively or additionally, it can be provided that after the physical imprinting of the blade grid into the steel strand, the steel strand undergoes thermohardening, whereby the heat treatment takes place at a heat treatment temperature and includes subsequent quenching. This contributes to achieving a homogeneous hardness distribution in the steel strand and meets the LD 44685 / WK - 13 - December 2025

[0060] To optimize material properties, especially the strength and wear resistance of the blades released later, the desired blade microstructure can be set at this stage, even before the blades are released. While the material can optionally be tempered subsequently, thermohardening essentially determines the target hardness. In particular, after thermohardening and / or strand tempering, a significantly softer steel strand may be present than would be required in conventional blade manufacturing processes, since the hardness of the steel strand is not relevant for brittle fracture during blade separation. In other words, the target blade hardness can be set without necessarily having to achieve the hardness required for brittle fracture during blade separation. Therefore, it is not necessary, for example, that the steel strand be completely or partially tempered.Steel strands, hardened to fracture hardness, are cooled uniformly, separated, and only then tempered intensively from ambient temperature.

[0061] Alternatively or additionally, the heat treatment temperature can be substantially at least 800 degrees Celsius, preferably at least 900 degrees Celsius, and particularly preferably at least 1000 degrees Celsius. Alternatively or additionally, it can be substantially at most 1300 degrees Celsius, preferably at most 1250 degrees Celsius, and particularly preferably at most 1200 degrees Celsius. Precise temperature control allows for the management of thermal effects on the steel strand, which is particularly important for hardness and ductility. Preferably, the heat treatment temperature is substantially 1150 degrees Celsius. With the aforementioned temperatures, the steel strand can be brought relatively close to the desired target blade hardness at a very early stage of processing, namely even before blade singulation.The heat treatment duration depends on the material mass and / or geometry, with complete annealing of the entire steel strand being preferable. This duration can range, for example, from 1 to 60 minutes, with five minutes ± two minutes being a frequently preferred value. These temperatures are particularly suitable for a steel strand made of bi- or trimetal with longitudinal steel strand edges featuring HSS side strips, for example, 1.3343. The phrase "essentially" allows for a range of ± 10 degrees Celsius.

[0062] Alternatively or additionally, it can be provided that, prior to the partial hardening of one or more indentations, the steel strand is tempered at a specific tempering temperature. This intermediate step improves the stress state in the material, and the steel structure can, for example, be adjusted to the final target hardness of the blade. Optionally, the steel strand can still be warm, preferably from heat treatment at a specific heat treatment temperature, and particularly preferably from thermohardening, so that the tempering can be carried out in an energy-optimized manner compared to the prior art.

[0063] A particular advantage is that the steel strand can be tempered to a much more ductile microstructure than a steel strand not processed according to the general principle outlined here. Up to now, steel strands have been tempered so that their hardness does not fall below 58 HRC, as otherwise brittle fracture would not be possible during subsequent singulation. In this case, the hardness can be reduced, for example, to 45 HRC as the target blade hardness, since the partial hardening of the fracture edges or indentations ensures brittle fracture despite the softer base material. In particular, unless otherwise stated, the hardness values ​​mentioned in this disclosure refer to the Rockwell hardness HRC according to DIN EN ISO 6508-1:2024-04, which corresponds in particular to the international standard ISO 6508-1:2023.

[0064] Alternatively or additionally, the physical imprinting can be achieved through stamping, in particular linear stamping, carried out by a stamping tool. This approach allows for precise production of the imprints and guarantees consistently high dimensional accuracy of the blades. Furthermore, the imprints can be parallel to each other and extend partially or completely between the outer edges of the steel extrusion, increasing material utilization efficiency and optimizing the blade shape.

[0065] Alternatively or additionally, the physical imprinting can be achieved by stamping, in particular linear stamping, which is carried out especially by stamping tools. This is a simple and therefore error-free method for physically imprinting the blade grid. Alternatively or additionally, it can be achieved that at least two, preferably several, and most preferably all imprints are formed parallel to each other. This is a simple and therefore error-free method and can be advantageous, for example, for snap-off blades, but also for other blades, such as machine cutting blades.

[0066] Alternatively or additionally, it may be provided that one or more indentations extend partially or completely between the outer edges of the steel strand, in particular partially or completely between both longitudinal edges of the steel strand. While a complete extension is understandable, a partial extension may mean that the indentations are executed as a dashed line and / or do not extend to the end of the actual fracture edge at one and / or both ends. For example, in the case of bi- or trimetals, it may be provided that the additional metal layers are not indented. Preferably, however, they may also be indented.

[0067] Alternatively or additionally, it can be provided that one or more indentations cause a longitudinal and / or transverse fracture of the steel strand. For a longitudinal fracture, an indentation should extend mainly along a longitudinal axis, in particular from a defined front end to a defined rear end. For a transverse fracture, an indentation should extend mainly along a transverse axis, in particular from a first longitudinal edge of the steel strand to a second longitudinal edge of the steel strand.

[0068] Alternatively or additionally, the steel strand can be provided with several indentations arranged in a regular blade grid relative to each other LD 44685 / WK - 16 - December 2025. The more regular the blade grid, the less personnel intervention is required, thereby increasing manufacturing efficiency.

[0069] Alternatively or additionally, the steel strand can be provided with several equidistant indentations along its longitudinal axis. This is particularly preferred for snap-off blades, machine cutting blades, and other blade types.

[0070] These are therefore, in particular, features or measures that further increase the manufacturing efficiency of the blades.

[0071] Alternatively or additionally, it can be provided that the partial hardening of one or more indentations, for example by means of laser radiation or by means of induction hardening, is carried out at a power of essentially at least 500 W, preferably at least 10 kW, particularly preferably at least 12 kW.

[0072] Alternatively or additionally, it can be provided that the partial hardening of one or more indentations, for example by means of laser radiation or by means of induction hardening, is carried out at a power of essentially at most 100 kW, preferably at most 50 kW, particularly preferably at most 30 kW.

[0073] Alternatively or additionally, partial hardening of one or more indentations can be carried out, for example, using laser radiation or induction hardening, at a power of essentially 15 kW. Precise power adjustment ensures controlled heat treatment of the indentations and improves the consistency of the hardened areas for blade singulation, resulting in high-quality break edges. This leads to increased process reliability, reduces scrap, and improves production efficiency. Furthermore, the quality of the end products is enhanced, as uniform hardening zones increase the durability and cutting resistance of the blades. The term "essentially" allows for a range of + / - 10 percent of the respective value. LD 44685 / WK - 17 - December 2025

[0074] Alternatively or additionally, it can be provided that the partial hardening per impression, for example by means of laser radiation or by means of induction hardening, takes place with a hardening time of substantially at least 0.2 seconds, preferably at least 0.3 seconds, particularly preferably at least 0.4 seconds.

[0075] Alternatively or additionally, it can be provided that the partial hardening per impression, for example by means of laser radiation or by means of induction hardening, takes place with a hardening time of essentially at most 1.0 seconds including 1.0 seconds, in particular at most 0.6 seconds including 0.5 seconds, preferably at most 0.4 seconds including 0.5 seconds.

[0076] Alternatively or additionally, partial hardening of each indentation can be performed, for example, using laser radiation or induction hardening, with a hardening time of essentially 0.4 seconds. The exact duration of the hardening process can be adjusted to the material thickness and the desired final hardness, which significantly improves the quality of the blade separation and the fracture edges. This adjustment ensures that the hardening is applied uniformly and in a controlled manner to the indentations without unnecessarily affecting the surrounding material. This results in cleaner fracture edges, reduces the risk of material defects or unwanted material breakage, and increases the durability and cutting strength of the manufactured blades. The term "essentially" allows for a range of + / - 10 percent of the respective value.

[0077] Alternatively or additionally, it can be provided that the partial hardening of one or more indentations, for example by means of laser radiation or by means of induction hardening, takes place at a frequency of essentially at least including 200 kHz, preferably at least including 250 kHz, particularly preferably at least including 300 kHz.

[0078] Alternatively or additionally, it may be provided that the partial hardening of one or more indentations, for example by means of laser radiation or by means of induction hardening, takes place at a frequency of essentially at most LD 44685 / WK - 18 - December 2025 including 400 kHz, preferably at most including 350 kHz, particularly preferably at most including 300 kHz.

[0079] Alternatively or additionally, partial hardening of one or more indentations can be carried out, for example, using laser radiation or induction hardening, at a frequency of approximately 300 kHz. The frequency is adjusted to the geometric and physical properties of the steel strand to achieve optimal heat penetration and enable effective laser radiation or induction hardening. Precise frequency adjustment allows the heating to be concentrated on the desired areas, increasing the efficiency of the hardening process and improving the quality of the hardened zones. An appropriate frequency also ensures a uniform hardness distribution and minimizes the risk of overheating or uneven hardening, resulting in improved material properties and increased durability and cutting resistance of the blades.The phrase "essentially" allows for a range of + / - 10 percent of the respective value.

[0080] Alternatively or additionally, it can be provided that, between the partial hardening of one or more indentations and the loading of the steel strand, the outer edges of the steel strand are ground, in particular the longitudinal edges of the steel strand are ground along its longitudinal axis. In this process, at least one longitudinal edge of the steel strand, preferably both, is ground. This measure is carried out on the steel strand, i.e., before the blade is released, and ensures an improved surface finish compared to grinding individual blades, thereby increasing the blade quality. Preferably, this step is performed as late as possible in the overall process to reduce the risk of injury to personnel, and is particularly preferably carried out as an immediate process step before loading the steel strand.

[0081] Alternatively or additionally, the loading process can be a mechanical one, whereby the breaking of the steel strand along the LD 44685 / WK - 19 - December 2025 results in at least a partially hardened indentation, particularly by means of buckling. This method can be particularly efficient and enable precise blade release. The loading can be carried out, for example, with a support system, which, in a single or multiple configuration, has a support point, a support line, or a support surface as the source of the load. The support system can be designed so that only one blade to be released is loaded at a time, or a single load application allows for multiple blade releases simultaneously. The loading process itself is already known from classic blade manufacturing methods, although in these cases it is completely or partially...The steel strands are uniformly hardened to fracture toughness, i.e., steel strands that are not partially hardened. By using partially hardened indentations, the risk of damage or breakage of the steel strand outside the intended blade grid can be reduced, thereby minimizing scrap and increasing the efficiency of the process.

[0082] Alternatively or additionally, the steel strand can be subjected to stress in such a way that it breaks only at the indentation closest to the stress source, releasing precisely one blade. This increases the controllability of the process and can minimize waste due to erroneous breakage. By selectively breaking only at the indentation closest to the stress source, the precision of blade release is improved. This can lead to more efficient production, as unwanted breaks elsewhere in the steel strand are avoided. Furthermore, material losses can be reduced and product quality increased because the blades are released in a controlled and precise manner. The improved process control can also increase safety by reducing unforeseen breakage points and the associated risks to personnel and equipment.

[0083] Alternatively or additionally, it may be provided that the loading of the

[0084] The steel strand is broken in such a way that it breaks at the indentation closest to the load source LD 44685 / WK - 20 - December 2025, as well as at subsequent indentations, simultaneously releasing multiple blades. This variant can significantly increase efficiency in the mass production of blades, as the simultaneous release of multiple blades increases production speed and throughput. Furthermore, setup times can be reduced and the overall production process optimized, leading to lower manufacturing costs. Coordinated breaking at multiple indentations also improves material flow and minimizes potential bottlenecks in the production process. However, it may be necessary to adjust the support system accordingly to allow for the simultaneous loading of multiple areas while still ensuring high precision in blade release.Therefore, this measure can increase manufacturing efficiency.

[0085] Alternatively or additionally, the blade can be a cutting blade, for example, a machine cutting blade, preferably equipped with at least one recess, and more preferably with at least one elongated hole, for blade mounting. The recess can facilitate mounting and increase the functionality of the blade by enabling simpler and more secure attachment in various mounting systems. The at least one recess, and more preferably an elongated hole, allows the blade to be flexibly positioned and adjusted, thus improving adaptability to different machines or tools. Optionally, this can also increase compatibility with existing blade holders and / or speed up blade replacement, thereby reducing downtime.Furthermore, the recess can help reduce the weight of the blade without affecting its stability or cutting performance, which can increase efficiency.

[0086] Alternatively or additionally, the steel strand, particularly in coil form, may be made from a single alloy. LD 44685 / WK - 21 - December 2025

[0087] Alternatively or additionally, the steel strand, particularly in coil form, can be made of a bimetal or trimetal, with the steel strand having a base body made of tool steel, for example 1.8159, and an HSS side strip, for example 1.3343, on one or both sides along the longitudinal edge of the steel strand for grinding the outer edge. This material combination can optimize the blade's properties for specific applications. Using a base body made of tool steel, for example 1.8159, creates a robust and tough base with good ductility and load-bearing capacity. The arrangement of an HSS side strip, for example 1.3343, on one or both sides along the longitudinal edge of the steel strand allows the cutting edges to be equipped with high hardness and wear resistance. This can significantly increase the blade's durability.

[0088] Optionally, this material combination can simplify heat treatment and external edge grinding of the steel extrusion, as the different materials can be treated specifically for their properties. By combining the tough properties of tool steel with the high hardness of HSS steel, blades can be produced that are both robust and extremely sharp and durable. This is particularly advantageous in applications that place high demands on cutting quality and blade lifespan, such as metalworking, woodworking, and other impact-prone cutting activities.

[0089] Furthermore, the use of bimetallic or trimetallic steel strands can increase production flexibility, as blades with specific properties can be manufactured for different applications. This material combination makes it possible to adapt the blades to the specific requirements of various cutting tasks, which can increase efficiency and reduce costs. Overall, this material composition can contribute to improving the performance and cost-effectiveness of blade production. LD 44685 / WK - 22 - December 2025

[0090] Alternatively or additionally, thermosetting can be used to adjust the steel strand to a target blade hardness, with the target hardness of the base body being essentially 450 HV 1, while, particularly in the case of bimetallic steels, the target hardness of the HSS side strips is essentially 760 HV 1. This can enable a balanced combination of hardness and toughness.

[0091] The hardness values ​​within the meaning of this disclosure can be determined in particular according to the Vickers hardness test method as specified in standards EN ISO 6507-1 to EN ISO 6507-4 in their version valid on the filing date. Such hardness values ​​can be determined, for example, with a test force of 1 kilopond, corresponding to 9.807 newtons, and an application time of 10 to 15 seconds.

[0092] Setting the target hardness of the base body to essentially 450 HV 1 ensures sufficient toughness and flexibility, thus increasing resistance to fracture and deformation. Simultaneously, particularly in the case of bi- or trimetals, the target hardness of the HSS side strips is set to essentially 760 HV 1, resulting in high cutting edge sharpness and wear resistance.

[0093] This material combination allows the advantages of both properties to be utilized: The tough core provides stability and fracture resistance, while the hard HSS side strips ensure excellent blade performance. This increases the impact resistance of the blades and improves efficiency in application. Optionally, this combination can adapt the blade to the specific impact-prone requirements of various cutting tasks by offering a balance between hardness and toughness that can be adjusted as needed. LD 44685 / WK - 23 - December 2025

[0094] Furthermore, this balanced hardness distribution can increase the blade's resilience and reduce the risk of chipping or damage to the cutting edge. This leads to greater reliability and quality of the blade in practical use. The precise adjustment of the hardness levels also allows for the optimization of heat treatment processes and energy savings, as only the necessary areas need to be treated to the respective target hardness.

[0095] Overall, this material composition can contribute to improving the efficiency and cost-effectiveness of blade production by delivering a blade that is robust, sharp, and durable. The phrase "essentially" allows for a range of + / - 10 percent of the respective value.

[0096] In this context, bimetal means, for example, that an HSS wire, also known as high-speed steel, is attached to the outer edge of a steel strand and flattened. This process combines the base of the steel strand, which consists of a tough or ductile material, with a hard and wear-resistant cutting edge made of HSS steel. This improves the impact resistance and durability of the blade without compromising the flexibility of the base material.

[0097] Trimetal is essentially an extension of bimetal. In this process, for example, an HSS wire is attached to each of the outer edges of the steel strand and flattened. This gives the blade two high-strength cutting edges, which is particularly advantageous for applications requiring double-sided cutting. This design combines the advantages of a tough base body with the high hardness and wear resistance of HSS steel on both cutting edges.

[0098] These material combinations can optimize the blade's properties for specific applications by offering a balanced ratio between toughness and hardness. They make it possible to adapt the blades to the specific requirements of various cutting tasks and to increase the efficiency and service life of the blades.

[0099] Another aspect focuses on a blade manufactured using the aforementioned process. Each blade edge, formed by a partially hardened indentation, has a hardened area that exhibits a higher hardness than the blade base material. The unhardened portion of the blade is considered the blade base material. This gives the blade increased impact resistance without compromising the toughness of the base material. As a result, the blade can be used in a wider range of applications compared to conventional blades, for example, in situations where the blade is subjected to impacts or unforeseen vibrations.

[0100] Alternatively or additionally, the hardening area from the partially hardened indentation to an edge of the hardening area located away from the corresponding indentation may be at most seven millimeters, preferably at most five millimeters, particularly preferably at most three millimeters, and most preferably at most two or one millimeter. Alternatively or additionally, the hardening area from the partially hardened indentation to an edge of the hardening area located away from the corresponding indentation may be at least 0.1 millimeters, preferably at least 0.5 millimeters, particularly preferably at least one millimeter, and most preferably at least two or three millimeters. Deviations of up to and including 10 percent from the respective values ​​are considered to fall below the respective value.In particular, the edge of the hardening area furthest from the respective indentation runs essentially parallel to the corresponding indentation. "Essentially" here means an angular deviation of approximately 10 degrees from the corresponding indentation. These hardening area values ​​are particularly suitable for multifunctional blades or blades exposed to unforeseen shocks. The precise dimensioning of the hardening area contributes to LD 44685 / WK - 25 - December 2025.

[0101] Optimization of the blade's hardness and toughness balance allows for targeted adaptation to specific application requirements.

[0102] Brief description of the drawings

[0103] A preferred technical solution is explained in more detail below with reference to the accompanying drawings and preferred embodiments. The term "figure" is abbreviated as "Fig." in the drawings.

[0104] The drawings show

[0105] Fig. 1 shows an arrangement of a longitudinal axis, transverse axis and depth axis relating to Figures 2 to 4;

[0106] Fig. 2 shows a top view of a snap-off blade steel strand according to a first embodiment;

[0107] Fig. 3 shows a top view of a trapezoidal blade steel strand according to a second embodiment; and

[0108] Fig. 4 shows a trapezoidal blade extracted from the trapezoidal blade steel strand according to Fig. 3.

[0109] LD 44685 / WK - 26 - December 2025

[0110] Detailed description of the drawings

[0111] The described embodiments are merely examples that can be modified and / or supplemented in various ways within the scope of the claims. Each feature described for a particular embodiment can be used independently or in combination with other features in any other embodiment. Each feature described for an embodiment of a particular claim category can also be used accordingly in an embodiment of a different claim category.

[0112] Figure 1 shows an arrangement of the longitudinal axis L, the transverse axis Q, and the depth axis T. These axes are arranged at 90-degree angles to each other, as in a Cartesian coordinate system. This arrangement applies to the following Figures 2 to 4 and is particularly relevant for the claimed process and blade features, independent of the figures. If a steel strand results from a coil, the axis arrangement applies to an unwound steel strand 12.

[0113] Figures 2 and 3 each show steel strands 12, while Figure 4 depicts a blade 10. All elements, processed in different steps, are subject to a method for manufacturing the blade 10 from the steel strand 12, which extends along the longitudinal axis L, the transverse axis Q, and the depth axis T. The steel strand 12 has a front end 14, a rear end 16, and parallel longitudinal edges 18a and 18b. The method comprises at least the following steps:

[0114] Physical imprinting 100 of a blade grid by means of imprints 20 into the steel strand 12;

[0115] Partial hardening of 200 of the impressions 20;

[0116] Apply a load of 300 to the steel strand 12, causing it to break along at least one partially hardened indentation 20; and LD 44685 / WK - 27 - December 2025

[0117] Release 400 at least one blade 10 from the steel strand 12, wherein this partially hardened indentation 20 forms an outer edge of the blade.

[0118] The results of these steps are shown in Figures 2 to 4 and illustrate the process of blade production from the steel strand 12.

[0119] Figure 2 shows a snap-off blade steel strand 12 suitable for producing two snap-off blades 10. In both snap-off blades 10, the physical imprinting 100 of a blade grid into the steel strand 12 has already been carried out, so that it is recognizable as a snap-off blade steel strand 12. As the depicted hardening areas 22 indicate, the partial hardening 200 of the imprints 20 has already been carried out on the upper snap-off blade 10; however, this has not yet been done on the lower snap-off blade 10.

[0120] Partial hardening allows for the hardening of only a specific hardening area 22 along the corresponding indentations 20, rather than the entire steel strand 12 as shown in Figures 2 and 3. When a partial hardening 200 of one or more indentations 20 is mentioned, this directly implies that the hardening area 22 is hardened along the corresponding indentations 20. The hardening area 22 is partially hardened around each indentation 20, for example, by seven millimeters, preferably by five millimeters, particularly preferably by three millimeters, and most preferably by two millimeters. An area of ​​one millimeter is also possible.

[0121] The wording "each" clarifies that the specified millimeter value per blade 10 extends to both sides of each indentation 20; that is, on the one hand, the millimeter value extends towards the blade 10, and on the other hand, into an adjacent blade 10 or into adjacent residual material. In other words, it is the amount by which the hardening area 22 extends proportionally along the longitudinal axis L and transverse axis Q, orthogonally away from the respective indentation 20 into the blade 10. LD 44685 / WK - 28 - December 2025

[0122] In particular, the edge of the hardening area 22 located away from the respective indentation 20 runs essentially parallel to the corresponding indentation 20. Therefore, the millimeter value specified for the blade 10 must be doubled for the entire width of the hardening area 22 according to the above dimensions in the steel strand 12.

[0123] Preferably, each hardening area 22 is uniformly dimensioned, in particular uniformly rib-shaped, along the corresponding indentation 20.

[0124] Figures 2 and 3 each show a steel strand 12 extending along the longitudinal axis L, the transverse axis Q, and the depth axis T. The steel strand 12 has a front end 14 and a distant rear end 16, both separated from each other along the longitudinal axis L. Furthermore, the steel strand 12 has two parallel longitudinal edges 18a and 18b, which act as outer edges and each extend from the front end 14 to the rear end 16.

[0125] The plane spanned by the outer edges 18a and 18b of the steel strands, consisting of the front end 14, the rear end 16 and the two parallel longitudinal edges 18a and 18b, forms in Figure 2 a blade grid for two snap-off blades by means of indentations 20 and in Figure 3 a blade grid for two trapezoidal blades with residual material in between.

[0126] Each hardening area 22 is preferably uniformly dimensioned, in particular uniformly rib-shaped, and arranged along the corresponding indentation 20. This uniform dimensioning of the hardening area 22 contributes to a consistent hardness distribution and enables reliable release of the blades 10.

[0127] In Figure 2, the indentations 20 of the steel strand 12 are parallel to each other and extend between the longitudinal edges 18a and 18b of the steel strand. The steel strand 12 has several equidistant indentations 20 along its longitudinal axis L, which are evenly distributed and serve as a blade grid for the production of the snap-off blades 10.

[0128] Figure 3 illustrates that the indentations 20 of the steel strand 12 are arranged in a regular blade grid. The steel strand 12 has several equidistant indentations 20 along its longitudinal axis L, with every second indentation 20 being identical. This arrangement ensures a uniform and efficient release of the trapezoidal blades 10 from the steel strand 12 with minimal residual material.

[0129] Figure 3 further indicates that between the partial hardening 200 and the loading 300 of the steel strand 12, a longitudinal edge 18b of the steel strand was ground. Subsequently, when the mechanical loading 300 of the steel strand 12 is carried out, whereby breaking along a partially hardened indentation 20 is caused by buckling, the blade 10 is released, as shown in Figure 4 as a trapezoidal blade.

[0130] This method can be particularly efficient and ensure precise blade release. Controlled breaking along the partially hardened indentations precisely controls the blade release, increasing process controllability and minimizing waste due to failed breakages. This improves blade quality and reduces production costs.

[0131] As shown in the figures, blade 10 is a cutting blade, more precisely a machine cutting blade.

[0132] Figures 3 and 4 indicate that the steel strand 12 and the blade 10 cut from it are designed as bimetal components, with a base body 24 made of tool steel and an HSS side strip 26 attached to the longitudinal edge 18b of the steel strand. This material combination can optimize the hardness and toughness of the blades and improve their performance in various applications. LD 44685 / WK - 30 - December 2025

[0133] Figure 4 shows a trapezoidal blade 10 that has been released from the trapezoidal blade steel strand 12. The trapezoidal blade 10 can be seen to have a base body 24 and an HS S side strip 26 on its second longitudinal steel strand edge 18a.

[0134] LD 44685 / WK - 31 - December 2025

[0135] Reference symbol list

[0136] 10 blades

[0137] 12 steel strands

[0138] 14 Front end

[0139] 16 Rear end

[0140] 18a Steel strand longitudinal edge (first)

[0141] 18b Steel strand longitudinal edge (second)

[0142] 20 Imprint

[0143] 22 Hardening area

[0144] 24 basic shapes

[0145] 26 HSS side stripes

[0146] 100 Physical imprinting of a blade grid into the steel strand

[0147] 110 thermosetting of the steel strand

[0148] 120 Steel strand tempering of the steel strand

[0149] 130 Steel extrusion outer edge grinding

[0150] 135 Steel strand longitudinal edge grinding

[0151] 200 partial hardenings of one or more impressions

[0152] 300 Loading the steel strand

[0153] 400 Release at least one blade

[0154] L Longitudinal axis

[0155] Q transverse axis

[0156] T Depth axis

Claims

LD 44685 / WK - 32 - December 2025 Claims 1. A method for manufacturing a blade (10) from a steel strand (12) having a longitudinal axis (L), a transverse axis (Q) and a depth axis (T), wherein the steel strand (12) has a front end (14) and a rear end (16), and wherein the steel strand (12) has steel strand outer edges with two parallel steel strand longitudinal edges (18a, 18b) extending from the front end (14) to the rear end (16), the method comprising at least the following steps: Physical imprinting (100) of a blade grid into the steel strand (12) such that the steel strand (12) has one or more imprints (20), wherein the blade grid represents a plurality of blades (10); Partial hardening (200) of one or more impressions (20); Applying a load (300) to the steel strand (12) such that the steel strand (12) breaks along at least one partially hardened indentation (20); and Releasing (400) at least one blade (10) from the steel strand (12), wherein the at least one partially hardened indentation (20) forms an outer edge of the blade.

2. Method according to claim 1, wherein after the physical imprinting (100) of the blade grid into the steel strand (12) a thermohardening (110) of the steel strand (12) is carried out, wherein the thermohardening (110) comprises heat treatment at a heat treatment temperature (T_H) and subsequent quenching.

3. The method of claim 2, wherein the heat treatment temperature (T_H) is substantially at least inclusive of 800 degrees Celsius, preferably substantially at least LD 44685 / WK - 33 - December 2025 including 900 degrees Celsius, particularly preferably substantially at least including 1000 degrees Celsius; and / or wherein the heat treatment temperature (T_H) is substantially at most including 1300 degrees Celsius, preferably substantially at most including 1250 degrees Celsius, particularly preferably substantially at most including 1200 degrees Celsius; and / or wherein the heat treatment temperature (T_H) is substantially 1150 degrees Celsius.

4. Method according to one of the preceding claims, wherein prior to the partial hardening (200) of one or more indentations (20) a steel strand tempering (120) of the steel strand (12) is carried out at a tempering temperature (T_A).

5. A method according to any one of the preceding claims, wherein the physical indentation (100) is a punching operation, in particular linear punching, which is carried out in particular by punching means; and / or wherein at least two, preferably several, particularly preferably all indentations (20) are formed parallel to each other; and / or wherein the one or more indentations (20) extend or extend partially or completely between the outer edges of the steel strand, in particular partially or completely between both longitudinal edges (18a, 18b) of the steel strand, and / or wherein one or more indentations (20) cause a longitudinal fracture and / or a transverse fracture of the steel strand; and / or wherein the steel strand (12) has several indentations (20) which are arranged in a regular blade grid relative to each other; and / or wherein the steel strand (12) has several equidistant indentations (20) along the longitudinal axis (L). LD 44685 / WK - 34 - December 2025 6. A method according to any one of the preceding claims, wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a power of substantially at least 500 W, preferably at least 10 kW, particularly preferably at least 12 kW; and / or wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a power of substantially at most 100 kW, preferably at most 50 kW, particularly preferably at most 30 kW; and / or wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a power of substantially 15 kW.

7. A method according to any one of the preceding claims, wherein the partial hardening (200) per indentation (20), for example by laser radiation or by induction hardening, is carried out for a hardening time of substantially at least 0.2 seconds, preferably at least 0.3 seconds, particularly preferably at least 0.4 seconds; and / or wherein the partial hardening (200) per indentation (20), for example by laser radiation or by induction hardening, is carried out for a hardening time of substantially at most 1.0 seconds, in particular at most 0.6 seconds, preferably at most 0.5 seconds, particularly preferably at most 0.4 seconds; and / or wherein the partial hardening (200) per indentation (20), for example by laser radiation or by induction hardening, is carried out for a hardening time of substantially 0.4 seconds. LD 44685 / WK - 35 - December 2025 8. A method according to any one of the preceding claims, wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a frequency of substantially at least 200 kHz, preferably at least 250 kHz, particularly preferably at least 300 kHz; and / or wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a frequency of substantially at most 400 kHz, preferably at most 350 kHz, particularly preferably at most 300 kHz; and / or wherein the partial hardening (200) of one or more indentations (20), for example by means of laser radiation or induction hardening, is carried out at a frequency of substantially 300 kHz.

9. Method according to any of the preceding claims, wherein between the steps Partial hardening (200) of one or more impressions (20); and Loading (300) of the steel strand (12); an outer edge grinding (130) of the steel strand (12) is carried out, in particular a longitudinal edge grinding (135) of the steel strand (12) is carried out along the longitudinal axis (L), wherein preferably at least one longitudinal edge (18a, 18b) of the steel strand, and particularly preferably both longitudinal edges (18a, 18b) of the steel strand are ground.

10. Method according to one of the preceding claims, wherein the loading (300) is a mechanical loading, in particular such that the breaking of the steel strand (12) along the at least one partially hardened indentation (20) is carried out by buckling. LD 44685 / WK - 36 - December 2025 11. Method according to one of the preceding claims, wherein the loading (300) of the steel strand (12) is carried out such that the steel strand (12) breaks exclusively at the indentation (20) nearest to the load source and releases exactly one blade (10) (400).

12. Method according to any one of claims 1 to 10, wherein the steel strand (12) is subjected to loading (300) in such a way that the steel strand (12) breaks at the indentation (20) nearest to the source of loading and at indentations (20) following thereto in the direction of the rear end (16) and simultaneously releases several blades (10) (400).

13. Method according to one of the preceding claims, wherein the blade (10) is a cutting blade, for example a machine cutting blade, preferably with at least one recess for blade retention, particularly preferably with at least one elongated hole for blade retention.

14. Method according to one of the preceding claims, wherein the steel strand (12), in particular formed as a coil, consists of a single alloy; or wherein the steel strand (12), in particular formed as a coil, consists of a bimetal or trimetal, wherein the steel strand (12) has a base body made of a tool steel, for example 1.8159, and has an HSS side strip, for example 1.3343, on one or both sides in a longitudinal edge orientation of the steel strand for grinding the outer edge (130) of the steel strand. LD 44685 / WK - 37 - December 2025 15. A method according to any of the preceding claims, wherein the thermohardening (110) adjusts the steel strand (12) substantially to a blade target hardness, wherein in particular the method is a method according to claim 14 and the target hardness of the base body is substantially 450 HV 1 and / or wherein the target hardness of one or both HSS side strips is substantially 760 HV 1.

16. Blade manufactured by a method according to one of claims 1 to 15, wherein each blade outer edge formed by a partially hardened indentation (20) has a hardening area (22) which in particular has a higher hardness than the blade base material.

17. Blade according to claim 16, wherein the hardening area (22) from the partially hardened indentation (20) to an edge of the hardening area (22) located away from the corresponding indentation (20) is at most seven millimeters, preferably at most five millimeters, particularly preferably at most three millimeters, and most preferably at most two or one millimeter; and / or wherein the hardening area (22) from the partially hardened indentation (20) to an edge of the hardening area (22) located away from the corresponding indentation (20) is at least 0.1 millimeters, preferably at least 0.5 millimeters, particularly preferably at least one millimeter, and most preferably at least two or three millimeters; and / or wherein, in particular, the edge of the hardening area (22) located away from the respective indentation (20) runs substantially parallel to the respective indentation (20).

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