Article provided with a plurality of micromechanical locking units on a surface portion and method for manufacturing such an article

Abstract

An article (1) and a method of manufacturing such an article, the article comprising: a steel base body (2) having a surface (3) provided with a plurality of micromechanical locking units for forming a micromechanical lock with another object when the micromechanical locking unit is pressed into a surface of the other object, the micromechanical locking unit comprising: a recess (6) surrounded by a ridge (7), wherein the angle of the surface of the recess that is intermediate between the bottom of the recess (6) and the top of the ridge (7) relative to the surface (3) is between 30° and 75°, preferably between 45° and 70°.

Description

Technical Field

[0001] This disclosure relates to articles having a steel surface or a steel-coated surface, and methods of manufacturing and using such articles, the surface being provided with a plurality of micromechanical locking units. Background Technology

[0002] In the absence of lubrication (clean and dry), the coefficient of static friction between sandwiched steel articles with smooth surfaces is between 0.12 and 0.25.

[0003] (https: / / roymech.org / Useful_Tables / Tribology / co_of_frict.html, Roymech.org) When constructing with steel articles clamped together, for example by bolts, the shear force—the force along the contact surfaces—is limited by the clamping force multiplied by the static friction coefficient and then a safety margin. Because the static friction coefficient between steel articles varies unpredictably, its minimum value must be used minus the safety margin. This means engineers must design using an effective static friction coefficient of 0.15 (sometimes a more conservative value of 0.10). Several methods for increasing steel-to-steel static friction are known, such as: - As known from WO2010118747, surface roughening provides a steel or iron friction member with a predetermined precise thickness, thereby generating high resistance to shearing motion when the friction member is pressed between two mating metal surfaces of at least two machine parts in a manner with at least two clamping devices for each friction element. To provide the pressing force, the friction member is provided with at least one friction surface to mate with a mating surface of one of the machine parts, and the document provides a method involving roughening the friction surface and then subjecting the roughened friction surface to non-depositional surface hardening. - Surface texturing is known from "A Novel Process for Manufacturing High-Friction Rings with a Closely Defined Coefficient of Static Friction (Relative Standard Deviation 3.5%) for Application in Ship Engine Components," published in Materials 2022, Vol. 15, No. 448, whereby coatings and hard particles are applied to the surface. - According to EP2773881B1, a method for manufacturing a brake disc is disclosed, which includes the following steps: a) providing a disc brake comprising a brake band 2 made of gray cast iron or steel and having two opposing brake surfaces 2a, 2b, each of the brake surfaces at least partially defining one of the two main sides of the disc; b) depositing a particulate material on the disc using HVOF (High-Speed ​​Oxygen Fuel) technology, or HVAF (High-Speed ​​Air Fuel) technology, or KM (Power Metallization) technology to form a protective coating 3 covering at least one of the two brake surfaces of the brake band, the particulate material comprising 70% to 95% tungsten carbide by weight, 5% to 15% cobalt by weight, and 1% to 10% chromium by weight. - As known from US6347905B1, a disc-shaped element with hard particles is applied between mating surfaces of articles. This document discloses a connecting element for friction-enhanced connection of workpieces to be joined. The connecting element is a thin, elastic element on which particles of a defined size are carried at the surface of the connecting element. These particles are made of a material whose compressive and shear strength exceeds that of the workpieces to be joined.

[0004] Materials, 2022, Vol. 15, No. 448, A Novel Process for Manufacturing High-Friction Rings with a Closely Defined Coefficient of Static Friction (Relative Standard Deviation 3.5%) for Application in Ship Engine Components, Wojciech S. Gora, Jesper V. Carstensen, Krystian L. Wlodarczyk, Mads B. Laursen, Erica B. Hansen and Duncan P. Hand (Materials 2022, 15, 448). https: / / doi.org / 10.3390 / ma15020448 discloses a laser surface texturing technique for manufacturing surfaces with a customized high static friction coefficient, maintained within a narrow range, for use in drive shafts of large marine engines. This is achieved by generating hexagonal patterned recesses on the surface using a nanosecond pulsed fiber laser. To provide a suitable friction coefficient, the surface is hardened using a chromium-based hardening process after laser treatment, so that when a normal force is applied in engine applications, the textured surface will be embedded in its corresponding portions. However, the resulting friction ring can only be clamped once and loses its predetermined friction coefficient relatively quickly upon repeated clamping.

[0005] WO2010118747A1 discloses a steel or iron friction member with a suitable thickness, thereby generating high resistance to shearing motion when the friction member is pressed between two mating metal surfaces of at least two machine parts in a manner with at least two clamping devices for each friction element. To provide the pressing force, the friction member is provided with at least one friction surface to engage with a mating surface of one of the machine parts. This friction surface is formed by a roughening step followed by non-depositional surface hardening of the roughened friction surface. WO2010118747A1 also discloses a method for providing a steel or iron friction member with a predetermined suitable thickness, thereby generating high resistance to shearing motion when the friction member is pressed between two mating metal surfaces of at least two machine parts in a manner with at least two clamping devices for each friction element. To provide the pressing force, the friction member is provided with at least one friction surface to engage with a mating surface of one of the machine parts. The method includes roughening the friction surface and then performing non-depositional surface hardening on the roughened friction surface. Therefore, a rough and hard surface is provided, wherein the protrusions of the rough surface can penetrate the mating surface to achieve mechanical locking.

[0006] EP3339658A1 discloses an article having a surface provided with a plurality of micromechanical locking units as described in the preamble of claim 1. In EP3339658A1, the micromechanical locking units are formed from hard particles fixed to a metal substrate by means of a metal bonding layer. However, none of the known methods provides a precisely controlled static friction coefficient that is independent of the presence of lubricant or dirt and remains substantially constant after the surfaces are clamped together multiple times. Summary of the Invention

[0007] The object of the present invention is to provide an article having a surface portion and a method for manufacturing such a surface portion, wherein the surface portion overcomes or at least alleviates the aforementioned problems.

[0008] The foregoing and other objectives are achieved through the features of the independent claims. Further implementations become apparent from the dependent claims, the description, and the drawings.

[0009] According to the first aspect, an article is provided, the article comprising: A steel substrate with a surface portion, The surface portion is provided with multiple micromechanical locking units, which are used to form a micromechanical lock with another object when the micromechanical locking unit is pressed into the surface portion of another object. The micromechanical locking unit includes: The concave portion surrounded by the ridge. The angle between the surface of the concave portion, located between the bottom of the concave portion and the top of the ridge portion, and the surface portion is between 30° and 75°, preferably between 45° and 75°.

[0010] The resulting object has a precisely predictable coefficient of static friction relative to another object—such as a steel object—regardless of the presence of lubricant and / or dirt, and maintains this coefficient of friction substantially after multiple clamping / unclamping events. Since the coefficient of static friction is substantially independent of the clamping condition of the surface and the number of times the surface has been clamped, engineers can use the reliable coefficient of static friction provided by this object. This has a significant advantage: engineers can use the higher coefficient of static friction provided by this object as a basis for their calculations of, for example, structures clamped by bolts / screws and the shear forces that such structures can withstand. This article can provide a reliable coefficient of static friction between approximately 0.8 and 1.2, which is approximately five to eight times higher than the commonly used reliable coefficient of static friction of 0.15 for untreated steel-to-steel connections. Therefore, this article allows, for example, bolt flange connections to withstand approximately five times the shear load compared to conventional steel-to-steel bolt flange connections—a significant improvement that will allow engineers to construct significantly lighter and more compact structures.

[0011] According to the possible implementation of the first aspect, the spacing between the central portions of the recesses is between 60µm and 200µm.

[0012] According to a possible implementation of the first aspect, the depth d of the recess, measured from the bottom of the recess to the top of the ridge, is 15µm to 100µm, preferably 30µm to 1000µm.

[0013] According to a possible implementation of the first aspect, the steel has a tensile strength between 420 N / mm² and 1630 N / mm², preferably between 600 N / mm² and 1200 N / mm².

[0014] According to a possible implementation of the first aspect, a hard layer or coating is provided on the surface portion, the hard layer preferably having a substantially uniform thickness.

[0015] According to the possible implementation of the first aspect, the thickness of the coating is between 3µm and 20µm, preferably between 5µm and 15µm.

[0016] According to the possible implementation of the first aspect, the ridge extends in the form of a roughly ring-shaped portion.

[0017] Depending on the possible implementation of the first aspect, the ridge has a diameter of 60µm to 200µm.

[0018] According to a possible implementation of the first aspect, the article is a plate-like piece having or including a plate-like piece having a thickness of 1 mm or less, preferably 0.5 mm or less; and / or wherein the article is a gasket.

[0019] According to a possible implementation of the first aspect, the surface portion of the article provided with multiple micromechanical locking units is configured to establish a micromechanical lock between the surface portion of article 1 and the mating surface portion by pressing the peak-shaped portion and / or ridge-shaped portion into the mating surface portion of another article, preferably wherein the surface pressure is between 5 MPa and 400 MPa.

[0020] According to a possible implementation of the first aspect, the micromechanical locking unit is arranged on the surface in the following pattern: the static friction coefficient generated by this pattern in the first direction is significantly higher than that generated in the orthogonal second direction.

[0021] According to a possible implementation of the first aspect, the pattern includes a plurality of straight arrays of micromechanical locking units arranged generally parallel to the second direction.

[0022] According to the possible implementation of the first aspect, the number of micromechanical locking units per unit surface area is selected to obtain a specific static friction coefficient.

[0023] According to the possible implementation of the first aspect, the micromechanical locking unit is formed on the smooth surface of the steel substrate by applying multiple laser pulses.

[0024] According to a possible implementation of the first aspect, the hard layer or coating is subsequently deposited on the steel substrate, preferably by chromium carbide diffusion coating.

[0025] According to the possible implementation of the first aspect, the ridge is a peak-shaped ridge.

[0026] According to a possible implementation of the first aspect, the hard layer is a hard chromium carbide layer, preferably a hard chromium carbide layer formed by diffusion coating on a steel substrate.

[0027] According to a possible implementation of the first aspect, the article is a disc-shaped piece with a central hole, and both sides of the disc-shaped piece are formed by a first contact surface.

[0028] According to a possible implementation of the first aspect, the article is a gripper that includes at least one gripping surface for engaging with an object to be gripped, and wherein the gripping surface is formed by a first contact surface.

[0029] According to a possible implementation of the first aspect, the article is a plate-like piece having or including a plate-like piece having a thickness of 1 mm or less, preferably 0.5 mm or less; and / or wherein the article is a gasket.

[0030] According to a second aspect, a method for manufacturing an object having a steel substrate is provided, the steel substrate having a surface portion provided with a plurality of micromechanical locking units, the micromechanical locking units being configured to form a micromechanical lock with the other object when the micromechanical locking unit is pressed into the surface portion of the other object, the method comprising: a) Apply laser pulses of a given intensity to the same location on the surface multiple times to form a recess surrounded by a ridge. b) Adjusting the number and / or intensity of the laser pulses to obtain a recess where the angle between the intermediate surface of the recess, located between the bottom of the recess and the top of the ridge, and the surface portion is between 30° and 75°, preferably between 45° and 55°. c) Repeat a) and b) at multiple other locations on the surface.

[0031] According to a possible implementation of the second aspect, c) is performed at various locations on the surface portion to obtain a spacing between 60µm and 200µm between the central portions of the recesses.

[0032] According to a possible implementation of the second aspect, the number and / or intensity of the laser pulses in b) are adjusted to obtain a recess having a depth d measured from the bottom of the recess to the top of the ridge: the depth d is between 30µm and 100µm, preferably between 40µm and 70µm.

[0033] According to a possible implementation of the second aspect, the steel has a tensile strength between 420 N / mm² and 1630 N / mm², and preferably between 600 N / mm² and 1200 N / mm².

[0034] According to a possible implementation of the second aspect, the method includes applying a hard layer or coating to the surface portion after the recess has been formed, the hard layer preferably having a substantially uniform thickness.

[0035] According to a possible implementation of the second aspect, the thickness is between 3µm and 20µm, preferably between 5µm and 15µm.

[0036] According to a third aspect, a method is provided for providing controlled static friction between an article and another article, the article and the other article being in contact through a surface portion of the article and a surface portion of the other article, the method comprising: The surface of the article is configured to have multiple micromechanical locking units, each of which includes: The peak-shaped portion includes a core peak-shaped portion formed from the steel substrate of the article, which is covered by a hard layer. And / or The ridge-like portion includes a core ridge-like portion formed from the steel substrate of the article, the core ridge-like portion being covered by a hard layer. Micromechanical locking units are arranged in a non-uniform distribution on the surface to obtain a static friction coefficient that is inconsistent in direction, and / or The number of micromechanical locking units per unit surface area is selected to obtain a specific static friction coefficient, and / or The micromechanical locking units are arranged in a curved or straight array to obtain the maximum static friction coefficient in a specific direction.

[0037] According to the possible implementation of the third aspect, the static friction coefficient is between 0.8 and 1.2.

[0038] According to a possible implementation of the third aspect, the method includes forming individual micromechanical locking units on a smooth surface portion of a steel substrate by applying a laser pulse, and preferably subsequently depositing a hard layer on the steel substrate, preferably by chromium carbide diffusion coating.

[0039] According to a possible implementation of the third aspect, the method includes establishing a micromechanical lock between the surface portion of one article and the surface portion of another article by pressing the peak portion and / or ridge portion into another surface portion.

[0040] According to a fourth aspect, a method is provided to prevent displacement between a first steel article and a second steel article, the first article having a first contact surface and the second article having a second contact surface, the method comprising: The first contact surface is configured with recesses using a pulsed laser, each recess being surrounded by ridges to form a micromechanical locking unit, wherein the recesses are spaced apart at a distance between 60µm and 200µm. The first contact surface is made into a hardened steel surface because the first steel article is a hardened steel article, or because the first steel article is a non-hardened steel article, and the method includes hardening the first contact surface by applying a hardened layer after the first contact surface is configured to have a recess. With or without lubricant between the first and second contact surfaces, a first force presses the first contact surface onto the second contact surface, thereby preventing displacement between the first and second steel articles when a second force pushes them to move in the direction along the first contact surface, until the second force exceeds at least 80% of the first force.

[0041] According to a possible implementation of the fourth aspect, the method includes: adjusting the power applied to the first contact surface by a pulsed laser for each recess to obtain a recess diameter between 35µm and 65µm.

[0042] According to a possible implementation of the fourth aspect, the method includes adjusting the power applied by a pulsed laser to the first contact surface for each recess to obtain a ridge height between 15µm and 30µm.

[0043] According to a possible implementation of the fourth aspect, the method includes applying a recess to the first contact surface in a hexagonal pattern.

[0044] According to a fifth aspect, an article is provided comprising an outer surface having at least a first contact surface formed of a steel substrate, the first contact surface having recesses, wherein each recess is surrounded by ridges to form a micromechanical locking unit for setting the first contact surface to have a contact surface static friction coefficient of at least 0.78, regardless of the presence or absence of lubricant on the first surface. The steel substrate is either a hardened steel substrate or a non-hardened steel substrate with a hardened layer thereon. The recesses are spaced apart by a distance between 60µm and 200µm, and the diameter of the recesses is between 35µm and 65µm.

[0045] According to the possible implementation of the fifth aspect, the height of the ridge is between 15µm and 30µm.

[0046] According to the possible implementation of the fifth aspect, the number of micromechanical locking units per unit surface area is selected to obtain a specific static friction coefficient.

[0047] These and other aspects become apparent through the examples and implementations described below. Attached Figure Description

[0048] In the following detailed description of this disclosure, various aspects, embodiments, and implementations will be described in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which: Figure 1This is a metallographic cross-sectional image of an article according to an embodiment, wherein epoxy resin is embedded on both sides for observation. Figure 2 It is based on a detailed cross-sectional image of the modified item, in which epoxy resin is embedded for observation. Figure 3 This is a top view of the surface portion of the article according to the embodiment. Figure 4 This is a cross-sectional view of an embodiment of an article in the form of a thin friction disc, which is clamped between two plate-shaped articles by means of a bolt connection. Figure 5 and Figure 6 They are Figure 5 Top and elevation views of the thin friction disc in the embodiment. Figures 7 to 9 This is a diagram showing the test results for an example. Detailed Implementation

[0049] Reference Figures 1 to 3 Article 1 has a steel substrate 2 with a surface portion 3 having a plurality of micromechanical locking units for forming a micromechanical lock with another object when the micromechanical locking unit is pressed into the surface portion of another object, preferably thereby obtaining a high static friction coefficient, preferably a precisely determined high friction coefficient that is largely affected by the presence of dirt or lubricant. Each micromechanical locking unit includes a recess (6) surrounded by a ridge (7). The micromechanical locking units are formed by a laser texturing method described in more detail below.

[0050] The recess 6 is substantially rotationally symmetric with respect to the normal of the surface portion. The surface of the recess 7 extends from the lowest point in the recess 6 to the peak or ridge portion 7 of the recess 6. The angle between the intermediate surface of the recess 6 located between the bottom of the recess 6 and the top of the ridge portion 7 and the surface portion 3 is between 30° and 75°, preferably between 45° and 70°, to obtain the desired characteristics of the surface portion 3 provided with the micromechanical locking unit as described below. The spacing between the central portions (deepest points) of the recess 6 is between 60µm and 200µm. The depth d of the recess 6, measured from the bottom of the recess 6 to the top of the ridge / peak portion 7, is between 15µm and 100µm, preferably between 30µm and 70µm. The ridge portion 7 is preferably a pointed ridge portion.

[0051] The steel substrate 2 preferably has a tensile strength between 420 N / mm² and 1630 N / mm², and more preferably between 600 N / mm² and 1200 N / mm².

[0052] Optionally, a hard layer or coating 9 is provided on the surface portion 3, which preferably has a substantially uniform thickness t1. The thickness t1 is preferably between 3µm and 20µm, more preferably between 5µm and 10µm.

[0053] The ridge or peak portion 7 may extend in a generally annular form and have a diameter of 60µm to 200µm.

[0054] In an embodiment, article 1 is a plate-like piece having a thickness t2 or includes a plate-like piece having a thickness t2, which is 1 mm or less, preferably 0.5 mm or less, and / or wherein article 1 is a gasket. Figure 5 and Figure 6 One embodiment is shown, in which article 1 is a friction disc. Figure 4 This illustrates an article 1 / friction disc bolted between two plate-like objects 10, such as flanges in a bolted flange connection. Bolts 12 (with nuts 14) apply forces in the normal direction to the surfaces of the plates 10 and the friction disc 1, as indicated by the vertical arrows. Shear forces, as indicated by the horizontal arrows, are applied to the two plate-like objects 10. The high coefficient of static friction provided by the friction disc allows the bolted connection to withstand relatively high shear forces, as illustrated in the example below.

[0055] During use of article 1, the ridge 7 is pressed into the mating surface portion, preferably with a surface pressure between 5 MPa and 450 MPa.

[0056] In one embodiment (not shown), the micromechanical locking units are arranged on the surface in a pattern that produces a significantly higher static friction coefficient in the first direction compared to the static friction coefficient produced in the orthogonal second direction. This pattern may include a plurality of straight arrays of micromechanical locking units arranged substantially parallel to the second direction.

[0057] In this implementation, the number of micromechanical locking units per unit surface area is selected to obtain a specific coefficient of static friction.

[0058] The micromechanical locking unit is formed in the smooth surface of the steel substrate 2 by applying multiple laser pulses.

[0059] In an embodiment, the hard layer or coating 9 is subsequently deposited on a steel substrate, preferably by diffusion coating of chromium carbide. The hard layer 9 may be a hard chromium carbide layer, preferably a hard chromium carbide layer formed by diffusion coating on the steel substrate 2.

[0060] Multiple micromechanical locking units are formed on the surface portion 3 of article 1 by repeatedly applying laser pulses of a given intensity to the same location on the surface portion 3 to create a recess 6 surrounded by a ridge 7. The power of each pulse can be different from each other, and the properties of the steel can be adjusted to obtain the desired shape and size of the recess 6 and its ridge 7. The number of pulses and / or the intensity of the laser pulses are adjusted to obtain a recess 6 in which the angle between the intermediate surface of the recess 6 located between the bottom of the recess 6 and the top of the ridge 7 and the surface portion 3 is between 30° and 75°, preferably between 40° and 70°, and this process is repeated at multiple other locations on the surface portion 3 to obtain a complete pattern of micro-locking units on the surface portion 3. Preferably, the spacing between the central portions of the recess 6 is between 60µm and 200µm.

[0061] The number and / or intensity of the laser pulses are adjusted to obtain a recess 6 having a depth d measured from the bottom of the recess 6 to the top of the ridge 7, wherein the depth d is between 15µm and 100µm, preferably between 30µm and 70µm.

[0062] Optionally, after the laser treatment that forms the recess 6, a hard layer or coating 9 is applied to the surface portion 3. This hard layer 9 preferably has a substantially uniform thickness t1. Preferably, the thickness t1 is between 3µm and 20µm, and more preferably between 5µm and 10µm.

[0063] Example: Example 1: A thin, coated disc-shaped part on both sides used to increase static friction in bolted connections, cross-sectional view as shown. Figure 1 As shown, and the top view of the surface portion is as follows Figure 3 As shown in the image.

[0064] • The disc-shaped part, made of annealed carbon steel 1.1248, is laser-cut to dimensions of Ø34xØ19x0.5mm, meaning the disc-shaped part has a central opening to allow the bolt shank to pass through this central opening. • Each side of the disk-shaped component is laser-textured using a pulsed fiber laser to create a hexagonal pattern of recesses. The spacing between the recesses is 85 ± 1 µm, and the recess depth is 45 ± 3 µm. See [link to documentation]. Figure 2 .

[0065] • The disc-shaped component is then subjected to a thermal reactive diffusion treatment to produce a chromium carbide coating covering both sides of the disc-shaped component, wherein the coating thickness is 5 ± 0.8 µm. See [link to relevant documentation]. Figure 1 .

[0066] • To evaluate the micromechanical interlocking effect, a disc-shaped component was positioned between two flanges of QT steel 1.2311 with a tensile strength of 1100 N / mm². The flanges were preloaded with 10.8 grade M18 bolts to generate a clamping pressure of 220 MPa on the disc-shaped component. One flange was fixed, while the other flange was gradually subjected to a rotational force. When the rotational force exceeded the frictional force between the disc-shaped component and the flange, one flange would rotate.

[0067] • Tests were conducted on five disc-shaped components, and the average static friction coefficient was found to be 1.18 ± 0.03. (See [reference needed]). Figure 7 The illustration is shown in the figure. Groups of untreated discs were also evaluated and tested, with a static friction coefficient of 0.23 + / - 0.06.

[0068] Example 2: Reuse of thin, coated discs with non-slipped, double-sided sections in bolt applications.

[0069] • Prepare fifteen disc-shaped pieces in the same manner as in Example 1.

[0070] • The static friction coefficient was evaluated according to Example 1, now preloaded with a clamping pressure of 100 MPa acting on the discs. Five discs were tested in their prepared state (a), and to simulate repeated use of the discs, the other five discs in each of the two groups were clamped and released five times (b) and twenty times (c) respectively before the sliding test. Sliding tests were performed on these discs, and the static friction coefficients for the three groups of five discs (a), (b), and (c) are shown as 0.86 ± 0.04, 0.84 ± 0.04, and 0.85 ± 0.03 respectively, see [reference needed]. Figure 8 The illustration in the diagram shows that re-tightening does not degrade the performance of the disc.

[0071] Example 3: Reusability of tested and slidable disc-shaped components • Five disc-shaped pieces made of annealed steel 1.1248 were laser-cut to dimensions of Ø34xØ19x0.5mm.

[0072] • Each side is laser-textured using a pulsed fiber laser to create a hexagonal pattern of recesses. The spacing between the recesses is 85 ± 1 µm, and the depth of the recesses is 55 ± 3 µm.

[0073] • The disc is then subjected to a thermal reactive diffusion treatment to produce a chromium carbide diffusion coating covering each surface of the disc, wherein the coating thickness is 10+ / -1.4µm.

[0074] • The static friction coefficient was evaluated according to Example 1, now with a clamping pressure of 70 MPa. The measured static friction coefficient was 0.82 + / - 0.04. Then, the same sliding test was performed again on the same five discs with the exact same parameters, and this test showed that the static friction coefficient did not decrease because the average value was evaluated as 0.84 + / - 0.03 (see Example 1). Figure 9 (Illustration in the image).

[0075] Example 4: High-friction clamp for tubular components • A mechanical clamp, measuring 40x32x24 mm and made of 1.2363 steel, is used to clamp the stainless steel tubular part during CNC machining of internal threads. Four clamping working areas, each measuring 20x12 mm, are laser-textured using a pulsed fiber laser to create a hexagonal recess pattern equivalent to the hexagonal recess pattern in Example 1. The working areas have a curved surface, Ø120, corresponding to the curved surface of the stainless steel tubular part.

[0076] • The clamp is then subjected to a thermal reactive diffusion treatment to produce a chromium carbide diffusion coating covering each surface of the clamp, wherein the coating thickness is 10+ / -1.1µm.

[0077] • Due to the micromechanical interlocking surface, when a clamping force of 40 tons is applied, the holding force of the gripper increases by 4.2 times compared to the holding force of a conventionally machined gripper surface.

[0078] Example 5: Directional static friction • Five plate-shaped pieces made of annealed steel 1.1248 were laser-cut to a size of 40x20x2mm.

[0079] • Each side is laser-textured using a pulsed fiber laser to form a linear patterned stadium-like section, with a width of 75 ± 1 µm, a height of 30 ± 5 µm, and a length of 200 ± 1 µm. The stadium-like section is parallel to the longest side of the plate-like component.

[0080] • The plate is then subjected to a thermal reaction diffusion treatment to produce a chromium carbide coating covering each surface of the plate, wherein the coating thickness is 10+ / -1.4µm.

[0081] • The static friction coefficient was evaluated by clamping the plate-like part on both sides in two 15mm x 15mm regions with a clamping pressure of 70MPa. The directional static friction coefficient could be measured by pulling the plate-like part along a direction parallel or perpendicular to the stadium-like part, causing it to slide. The friction coefficient measured in the direction parallel to the stadium-like part was 0.48 + / - 0.07, while the measured value in the perpendicular direction was 0.78 + / - 0.06.

[0082] Example 6: Application of high-pressure bolt connections with shallow recesses • Prepare five disc-shaped pieces using the same materials and dimensions as in Example 1.

[0083] • Each side of the disc-shaped component is laser-textured using a pulsed fiber laser to create a hexagonal pattern of recesses. The spacing between the recesses is 80 ± 1 µm, and the depth of the recesses is 24 ± 2 µm.

[0084] • The disc is then subjected to a thermal reaction diffusion treatment to produce a chromium carbide coating covering both sides of the disc, wherein the coating thickness is 6+ / -0.7µm.

[0085] • For structural steel S235, the static friction coefficient was evaluated according to the test procedure in Example 1, now preloaded with a clamping pressure of 300 MPa acting on the disc. A sliding test was performed on the disc, and the static friction coefficient was shown to be 1.06 + / - 0.06.

[0086] In another embodiment, a method is provided for providing controlled static friction between an article and another article, the articles being in contact through a surface portion of the article and a surface portion of the other article. The method includes: The surface of the article is configured to have multiple micromechanical locking units, each of which includes: Peak-shaped portion, comprising a core peak-shaped portion formed from the steel substrate of the article, the core peak-shaped portion being covered by a hard layer, and / or The ridge-like portion includes a core ridge-like portion formed from the steel substrate of the article, the core ridge-like portion being covered by a hard layer. The micromechanical locking units are arranged in a non-uniform distribution on the surface to obtain a static friction coefficient that is inconsistent in direction, and / or The number of micromechanical locking units per unit surface area is selected to obtain a specific coefficient of static friction, and / or The micromechanical locking units are arranged in a curved or straight array to obtain the maximum static friction coefficient in a specific direction. Preferably, the static friction coefficient is between 0.8 and 1.2.

[0087] The method may further include forming individual micromechanical locking units on a smooth surface portion of a steel substrate by applying a laser pulse, and preferably subsequently depositing a hard layer on the steel substrate, preferably by chromium carbide diffusion coating.

[0088] The method may also include establishing a micromechanical lock between the surface of one article and the surface of another article by pressing the peaks and / or ridges into the other surface.

[0089] According to another embodiment, a method is provided to prevent displacement between a first steel article and a second steel article, the first article having a first contact surface and the second article having a second contact surface. The method includes: The first contact surface is configured with recesses using a pulsed laser, wherein each recess is surrounded by ridges to form a micromechanical locking unit, and the recesses are spaced apart from each other at a distance between 60µm and 200µm. The first contact surface is made into a hardened steel surface because the first steel article is a hardened steel article, or because the first steel article is a non-hardened steel article, and the method includes hardening the first contact surface by applying a hardened layer after the first contact surface is configured to have a recess. With or without lubricant between the first and second contact surfaces, a first force presses the first contact surface onto the second contact surface, thereby preventing displacement between the first and second steel articles when a second force pushes them to shift along the direction of the first contact surface, until the second force exceeds at least 80% of the first force. Preferably, the method includes adjusting the power applied by a pulsed laser to the first contact surface for each recess to obtain a recess diameter between 35µm and 65µm.

[0090] Preferably, the method includes applying a recess to the first contact surface in a hexagonal pattern.

[0091] According to another embodiment, an article 1 including an outer surface 4 is provided, the outer surface 4 having at least a first contact surface formed of a steel substrate 2, the first contact surface 3 having recesses 6, wherein each recess 6 is surrounded by ridges 7 to form a micromechanical locking unit to set the first contact surface to have a contact surface static friction coefficient of at least 0.78, regardless of whether a lubricant is present on the first surface 3, the steel substrate 2 being a hardened steel substrate or a non-hardened steel substrate having a hardened layer thereon, the recesses 6 being spaced apart from each other at a distance between 60µm and 200µm, and the recess diameter being between 35µm and 65µm. Preferably, the surface area is selected to obtain a specific size of static friction coefficient.

[0092] Various aspects and implementations have been described in conjunction with the various embodiments described herein. However, those skilled in the art, when practicing the claimed subject matter, will understand and implement other variations of the disclosed embodiments by studying the drawings, the disclosure, and the appended claims. In the claims, the term "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality.

[0093] The reference numerals used in the claims should not be construed as limiting the scope. Unless otherwise stated, the drawings are intended to be read in conjunction with the specification (e.g., section lines, arrangement of components, scale, extent, etc.) and should be considered part of the entire written description of this disclosure. As used in the specification, the terms “horizontal,” “vertical,” “left,” “right,” “up,” and “down,” and their adjective and adverbial derivatives (e.g., “horizontally,” “to the right,” “upward,” etc.) refer only to the orientation of the illustrated structure when the particular drawing is facing the reader. Similarly, the terms “inward” and “outward” generally refer to, where applicable, the orientation of a surface relative to its elongated axis or axis of rotation.

Claims

1. An article (1), said article (1) comprising: A steel substrate (2) having a surface portion (3). The surface portion (3) is provided with a plurality of micromechanical locking units, which are used to form a micromechanical lock with the other object when the micromechanical locking unit is pressed into the surface portion of the other object. The micromechanical locking unit is characterized in that it comprises: a recess (6) surrounded by a ridge (7), Wherein, the angle between the middle surface of the recess (6) located between the bottom of the recess (6) and the top of the ridge (7) and the surface portion (3) is between 350° and 75°. Preferably, the angle between the middle surface of the recess (6) located between the bottom of the recess (6) and the top of the ridge (7) and the surface portion (3) is between 455° and 75°.

2. The article (1) according to claim 1, wherein, The spacing between the central portions of the recesses (6) is between 60 µm and 200 µm.

3. The article (1) according to claim 1 or 2, wherein, The depth (d) of the recess (6) from the bottom of the recess (6) to the top of the ridge (7) is 15 µm to 100 µm, preferably 30 µm to 100 µm.

4. The article (1) according to any one of claims 1 to 3, wherein, The steel of the matrix has a tensile strength between 420 N / mm² and 1630 N / mm², preferably, the steel of the matrix has a tensile strength between 600 N / mm² and 1200 N / mm².

5. The article (1) according to any one of claims 1 to 4, wherein, A hard layer or a coating (9) is provided on the surface portion (3), preferably the hard layer having a substantially uniform thickness (t1).

6. The article (1) according to claim 5, wherein, The thickness (t1) is between 3 µm and 20 µm, preferably between 5 µm and 10 µm.

7. The article (1) according to any one of the preceding claims, wherein, The ridge (7) extends in a generally annular form.

8. The article (1) according to claim 7, wherein, The ridge (7) has a diameter of 60 µm to 200 µm.

9. The article (1) according to any one of the preceding claims, wherein, The article (1) is a plate with a thickness (t2), or the article (1) comprises a plate with a thickness (t2) of 1 mm or less, preferably 0.5 mm or less, and / or wherein the article (1) is a gasket.

10. The article (1) according to any one of the preceding claims, wherein, The surface portion of the article (1) having a plurality of the micromechanical locking units is configured to establish a micromechanical lock between the surface portion of the article (1) and the mating surface portion by pressing the ridge portion (7) into the mating surface portion of another article (10), preferably wherein the surface pressure is between 5 MPa and 450 MPa.

11. The article (1) according to any one of the preceding claims, wherein, The micromechanical locking unit is arranged on the surface in the following pattern: the static friction coefficient generated by the pattern in the first direction (d1) is significantly higher than that generated in the orthogonal second direction (d2).

12. The article (1) according to claim 11, wherein, The pattern includes a plurality of straight arrays (9) of micromechanical locking units (40) arranged to be substantially parallel to the second direction (d2).

13. The article (1) according to any one of claims 1 to 12, wherein, The number of micromechanical locking units per unit surface area is selected to obtain a specific coefficient of static friction.

14. The article (1) according to any one of claims 1 to 21, wherein, The micromechanical locking unit is formed in the smooth surface of the steel substrate (2) by applying multiple laser pulses.

15. The article (1) according to claim 14 of claim 5, wherein, The hard layer or coating (9) is then deposited on the steel substrate, preferably, the hard layer or coating (9) is then deposited on the steel substrate by chromium carbide diffusion coating.

16. The article (1) according to any one of claims 1 to 15, wherein, The ridge (7) is a peak-shaped ridge.

17. The article (1) according to any one of claims 5 to 16, wherein, The hard layer (9) is a hard chromium carbide layer. Preferably, the hard layer (9) is a hard chromium carbide layer formed by diffusion coating on the steel substrate (2).

18. A method for manufacturing an article having a steel substrate (2) having a surface portion (3) having a plurality of micromechanical locking units provided thereon, the micromechanical locking units being configured to form a micromechanical lock with the other object when the micromechanical locking unit is pressed into the surface portion of the other object, the method comprising: a) Apply laser pulses at a given intensity to the same location on the surface portion (3) multiple times to form a recess (6) surrounded by the ridge portion (7). b) Adjusting the number and / or intensity of the laser pulses to obtain a recess (6) in which the angle between the intermediate surface of the recess (6) located between the bottom of the recess (6) and the top of the ridge (7) and the surface portion (3) is between 30° and 75°; preferably, the angle between the intermediate surface of the recess (6) located between the bottom of the recess (6) and the top of the ridge (7) and the surface portion (3) is between 45° and 75°, and c) Repeat a) and b) at multiple other locations on the surface portion (3).

19. The method according to claim 18, wherein, c) is performed at various locations on the surface portion (3) to obtain a gap between 60 µm and 200 µm between the central portions of the recess (6).

20. The method according to claim 18 or 19, wherein, The number and / or intensity of the laser pulses in b) are adjusted to obtain a recess (6) having a depth d) measured from the bottom of the recess (6) to the top of the ridge (7): the depth d) is between 15 µm and 100 µm, preferably between 3040 µm and 100 µm.

21. The method according to any one of claims 18 to 20, wherein, The steel has a tensile strength between 420 N / mm² and 1630 N / mm², preferably between 600 N / mm² and 1200 N / mm².

22. The method according to any one of claims 18 to 21, wherein the method comprises: After the recess (6) has been formed, a hard layer or coating (9) is applied to the surface portion (3), preferably the hard layer (9) having a substantially uniform thickness (t1).

23. The method according to claim 22, wherein, The thickness (t1) is between 3 µm and 20 µm, preferably between 5 µm and 10 µm.

24. A method for providing controlled static friction between an article and another article, the articles being in contact with each other through a surface portion of the article and a surface portion of the other article, the method comprising: The surface of the article is configured to have multiple micromechanical locking units, each micromechanical locking unit comprising: The peak-shaped portion includes a core peak-shaped portion formed from the steel substrate of the article, the core peak-shaped portion being covered by a hard layer. And / or The ridge-like portion includes a core ridge-like portion formed from the steel substrate of the article, the core ridge-like portion being covered by a hard layer. The micromechanical locking units are arranged in a non-uniform distribution on the surface portion to obtain a static friction coefficient that is inconsistent in direction, and / or The number of micromechanical locking units per unit surface area is selected to obtain a specific coefficient of static friction, and / or The micromechanical locking units are arranged in a curved array or a straight array to obtain the maximum static friction coefficient in a specific direction.

25. The method according to claim 24, wherein, The static friction coefficient is between 0.8 and 1.

2.

26. The method according to claim 24 or 26, the method comprising forming the respective micromechanical locking units on the smooth surface of the steel substrate by applying a laser pulse, and preferably, subsequently depositing the hard layer on the steel substrate, preferably, subsequently depositing the hard layer on the steel substrate by chromium carbide diffusion coating.

27. The method according to any one of claims 24 to 27, the method comprising establishing a micromechanical lock between a surface portion of the article and a surface portion of the other article by pressing the peak portion and / or the ridge portion into another surface portion.

28. A method for preventing displacement between a first steel article and a second steel article, the first article having a first contact surface and the second article having a second contact surface, the method comprising: The first contact surface is configured with recesses using a pulsed laser, wherein each recess is surrounded by ridges to form a micromechanical locking unit, and the recesses are spaced apart from each other at a distance between 60 µm and 200 µm. The first contact surface is made into a hardened steel surface because the first steel article is a hardened steel article, or because the first steel article is a non-hardened steel article, and the method includes hardening the first contact surface by applying a hardening layer after setting the first contact surface to have a recess. With or without lubricant between the first and second contact surfaces, a first force presses the first contact surface onto the second contact surface, thereby preventing displacement between the first and second steel articles when a second force pushes the first and second steel articles to move in the direction along the first contact surface, until the second force exceeds at least 80% of the first force.

29. The method of claim 27, wherein the method comprises: The power applied to the first contact surface by the pulsed laser for each recess is adjusted to obtain a recess diameter between 35 µm and 65 µm.

30. The method according to claim 27 or 28, wherein the method comprises: The power applied to the first contact surface by the pulsed laser for each recess is adjusted to obtain a ridge height between 15 µm and 30 µm.

31. The method according to any one of claims 27 to 29, the method comprising applying the recess to the first contact surface in a hexagonal pattern.

32. An article comprising an outer surface having at least a first contact surface formed of a steel substrate, the first contact surface having a recess, wherein... Each recess is surrounded by a ridge to form a micromechanical locking unit, the micromechanical locking unit being used to set the first contact surface to have a contact surface static friction coefficient of at least 0.78, regardless of the presence of lubricant on the first surface. The steel substrate can be a hardened steel substrate or a non-hardened steel substrate, wherein the non-hardened steel substrate has a hardened layer. The recesses are spaced apart from each other at a distance between 60 µm and 200 µm, and the diameter of the recesses is between 35 µm and 65 µm.

33. The article according to claim 31, wherein, The height of the ridge is between 15 µm and 30 µm.

34. The article according to claim 32 or 33, wherein, The number of micromechanical locking units per unit surface area is selected to obtain a specific coefficient of static friction.

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