MANUFACTURING METHOD FOR PRODUCING THE ADVANCED SEAL TO SUPPORT LOW DROWING TORQUE

Abstract

Method for manufacturing a sealing element (1) for a caliper brake, wherein the sealing element (1) has a ring shape with a desired cross-section, comprising the following steps: Providing (S1) a sealing blank (2, 3) around a fastening core (4), either as a tube (3) or as a ring element (2) of a defined width, cut from a tube (3) by a first cutting tool (5), radial expansion (S2) of the sealing blank (2, 3), Cutting chamfers (S3) on the inner and outer diameter of the sealing blank (2, 3) on at least one axial surface of the sealing blank (2, 3) with a second cutting tool (6) and, if the sealing blank (2, 3) is provided as a tube (3), cutting the ring element (2) from the tube (3) with a first cutting tool (5), Relaxing (S4) the sealing blank (2) back into its original geometry and removing the fastening core (4), resulting in the sealing element (1) with the desired cross-section, wherein during the step of cutting chamfers (S3) on the inner and outer diameter of the sealing blank (2) additional surface treatments are carried out.

Description

[0001] This invention relates to a method for manufacturing a sealing element for a saddle brake, wherein the sealing element has a ring shape with a desired cross-section.

[0002] In floating caliper brakes, a caliper moves relative to a brake disc. A piston first pushes an inner brake pad to one side of the disc and then pulls the caliper housing with the outer brake pad to make contact with the outside of the disc, thus applying pressure to both sides of the brake disc. However, this brake design is prone to drag torque, which is caused by the piston not fully retracting due to dirt or corrosion within the caliper housing. This results in the brake pads rubbing against the brake disc even when the brake is released.

[0003] Consequently, reducing drag torque is a priority in improving the function of caliper brakes. One way to reduce residual drag torque is through the use of a piston seal element that assists the piston's return roll. A seal element is generally provided in a recess of the cylinder that accommodates the piston in the caliper housing. This seal element seals the space between the inner surface of the cylinder and the outer surface of the piston, thus preventing brake fluid leakage and the ingress of contaminants. Furthermore, the seal element is able to assist the piston's return roll by elastically deforming when the piston is compressed during braking and elastically restoring its original shape when the brake is released.EP 3 988 812 A1 found that sealing elements with certain cross-sections improve roll-back performance. These improved sealing element designs, for example, the one described with a protrusion on the surface of the sealing element facing the forward direction of the piston, provide the sealing element with improved durability and deformation response under pressure and can thus improve roll-back, thereby preventing drag torque.

[0004] However, while conventional ring- or cylinder-shaped sealing elements with rectangular cross-sections are simple and common components that are straightforward and inexpensive to produce, manufacturing a sealing element as described in EP 3 988 812 A1 is a different matter. Providing the sealing element with protrusions or any desired cross-section requires additional manufacturing steps, such as additive manufacturing processes like bonding multiple parts together or injection molding. Consequently, current manufacturing methods that enable the production of the required sealing element result in increased costs in terms of both material and production time, or in a sealing element of inferior quality.From JP S60-120 041 A, a method for manufacturing profile sealing rings by turning and cutting hose bodies is further known, which includes the use of an expanding mandrel or a chuck to clamp the elastic rotating body during the machining of the sealing surfaces.

[0005] Accordingly, the objective of the present application is to provide a method for manufacturing a sealing element for a caliper brake which makes it possible to achieve a large number of cross-sections in a simple and inexpensive manner.

[0006] This problem is solved by the method for manufacturing a sealing element for a saddle brake according to claim 1.

[0007] In particular, the method for manufacturing a sealing element for a caliper brake, wherein the sealing element has a ring shape with a desired cross-section, comprises the following steps: Providing a sealing blank around a mounting core or as a ring element of a defined width, cut from a tube by a first cutting tool, Radial expansion of the sealing blank, Cutting chamfers on the inner and outer diameter of the sealing blank on at least one axial surface of the sealing blank with a second cutting tool and, if the sealing blank is provided as a tube, cutting the ring element from the tube with a first cutting tool, Relaxing the sealing blank back into its original geometry and removing the fastening core results in the sealing element with the desired cross-section.

[0008] A sealing blank can be provided either as a tube around a mounting core or as a ring element of a defined width, cut from a tube by a primary cutting tool. The tube can be made of any elastic material conventionally used for seals, such as rubber, silicone, or polyurethane, and related components. The mounting core is generally cylindrical and can be solid or hollow. Together with the sealing blank, the mounting core rotates around a cylindrical axis.

[0009] When the sealing blank is cut to a defined width, the first step largely corresponds to the production of a conventional annular sealing element: an annular element is cut from a tube of elastic sealing material, supplied around a mounting core, using a first cutting tool. The first cutting tool is a machine equipped with cutting blades that can be moved towards the tube to cut it as it rotates. The mounting core can be cut together with the tube, or the sealing blank can remain attached to the same mounting core. The annular element has a defined width along its circumference and a generally rectangular cross-section. However, the sealing blank can also be the tube itself, which is then processed in subsequent steps before being cut to produce a sealing element.

[0010] The resulting sealing blank therefore comprises either a tubular or annular element of the elastic sealing material, which is provided around part of the fastening core.

[0011] The directions mentioned below are defined by the cylindrical shape of the hose and the mounting core. A direction designated as "axial" is generally parallel to the direction of the hose's axis of rotation. A "radial" direction is perpendicular to this axis and coincides with the hose's radius. The hose's circumference defines a third direction, useful when considering the cross-section of the sealing element. An "inner diameter" refers to the diameter of the hose's inner surface, while an "outer diameter" refers to the diameter of the hose's outer surface.

[0012] The sealing blank either has the defined width of the ring element in the axial direction, which is generally constant for the entire blank, or the width of the seal corresponds to the width of the original hose. A sealing blank also has an inner diameter and an outer diameter in the radial direction of the sealing blank, which corresponds to the thickness of the original hose.

[0013] In a second step, the sealing blank is then radially expanded. Accordingly, either the inner diameter or the outer diameter, or both, are increased. This preloads the sealing blank in a radial direction. Deformation of the elastic sealing material also leads to a preload in an axial direction.

[0014] In the third step, the sealing blank is cut by a second cutting tool to create chamfers on at least one axial surface of the blank, both on its inner and outer diameters. These chamfers give the sealing element the desired cross-section. If the sealing blank is a ring, both axial surfaces can be cut simultaneously. If it is a tube, only one axial surface is accessible. The chamfer geometries are predefined and limited only by the cutting tool used. This allows for the production of a wide range of protrusions and convex surfaces without the need for additive manufacturing. Depending on the cutting tool, multiple edges of the sealing blank can be cut at once, or the chamfers can be produced sequentially.Cutting the chamfers while the gasket blank is pre-stressed improves the stiffness of the edges.

[0015] If the sealing blank was the complete hose up to this point, the hose is then cut by the first cutting tool to produce a ring element.

[0016] After cutting the chamfers and, if necessary, the ring element, the sealing blank can then relax from its radially expanded state back to its original radial dimension. The retaining core is removed. The result is a sealing element with the diameter of the original hose, but with the desired cross-section.

[0017] The sealing blank can be radially expanded by simultaneously increasing both its inner and outer diameters. This pre-stresses and elongates the sealing blank in the radial direction, while the width of the ring element can be increased in the axial direction due to material deformation. Depending on the material's stiffness and the degree of pre-stressing, the sealing blank's thickness can also be reduced.

[0018] One way to expand the sealing blank in both its inner and outer diameters is to radially expand the mounting core. This requires a hollow or at least deformable mounting core and allows for easy preloading of the sealing blank.

[0019] Alternatively, it is possible to widen the gasket blank only at its outer diameter. Only the outer diameter of the gasket blank is increased, while the inner diameter remains the same. This increases the thickness of the gasket blank, but depending on the stiffness of the material and the degree to which the gasket blank is pre-stressed, the width of a ring element may also be reduced.

[0020] One way to expand the gasket blank at only its outer diameter is to use a vacuum device attached to the outer diameter of the gasket blank. This method also requires a second cutting tool capable of cutting the chamfers while the vacuum is applied.

[0021] An alternative method for expanding the gasket blank at only its outer diameter involves utilizing centrifugal force. For this approach, additional masses can be attached to the gasket blank and rotated either in the same or opposite direction to the mounting core. By applying the additional masses to the circumference of the gasket blank in specific patterns, the formation of contours on an axial surface of the gasket blank can also be influenced, thus enhancing the chamfer cutting effect under pre-stressed conditions.

[0022] The second cutting tool for cutting the chamfers can be a novel cutting tool that allows the chamfers to be cut simultaneously on the inner and outer diameters of the gasket blank. Accordingly, the time required for gasket production can be reduced.

[0023] The first cutting tool can also be used as the second cutting tool. Conversely, the second cutting tool can also be configured to include the cutting blades necessary to perform the first step of cutting the sealing blank from the hose. Consequently, one cutting tool can be used for both steps, reducing the number of tools required.

[0024] It is also possible to essentially combine the first and third steps if the gasket blank can be radially expanded while the cutting tool is being used. Accordingly, the time required for gasket production can be further reduced.

[0025] The cutting of the chamfers by the second cutting tool can be controlled by a CNC machine. With a CNC machine, the process can be fully automated, and a wide selection of possible desired cross-sections can be pre-programmed and calculated.

[0026] The desired cross-section can include an axial surface of the sealing element with at least one projection. This type of cross-section has proven advantageous for roll-back in a caliper brake and can be easily achieved by removing material from the edge of the axial surface. At least one projection, or a number of projections, can also be provided on both axial surfaces of the sealing element.

[0027] The desired cross-section can be provided with a convex shape on one axial surface of the sealing element. Essentially, a convex surface also functions as a protrusion, but the rounded edges improve the durability of the sealing element. Manufacturing convex shapes on the axial surfaces of the sealing element would be particularly complex without the proposed method. Convex shapes can also be provided on both axial surfaces.

[0028] The desired cross-section can include a sealing element with a smaller thickness on one axial surface in the radial direction than on the other axial surface. This cross-section can also improve the sealing element's resistance to rollback.

[0029] The desired cross-section can vary along the circumference of the ring shape of the sealing element. Accordingly, some or all of the aforementioned cross-sections can be provided along the circumference of a sealing element to achieve the desired effects.

[0030] As can be seen, a wide variety of different cross-sections can be achieved using the proposed method. It should also be mentioned that this list is not exhaustive; instead, the method can be used for any continuous cross-section.

[0031] The process further includes additional surface treatments of the sealing blank, which are performed during the chamfer cutting step on the inner and outer diameters of the sealing blank. Such surface treatments can include modifications to the coefficient of friction or surface hardness of the sealing material to impart additional beneficial qualities to the sealing element. Combining surface treatments allows for a further reduction in the complexity and time required for the production of the sealing element.

[0032] The described features can be freely combined to achieve additional effects, in order to provide a method for manufacturing a sealing element for a caliper brake, which makes it possible to achieve any desired cross-sections in an easy-to-use manner.

[0033] The aforementioned aspects, as well as further aspects of the invention, will become clear from the detailed description of the embodiments with the aid of the following drawings, of which: Fig. Figure 1 illustrates a conventional method for manufacturing a sealing element for a caliper brake, Fig. 2 illustrates the method for manufacturing a sealing element with a desired cross-section according to a first embodiment, Fig. 3 illustrates the method for manufacturing a sealing element with a desired cross-section according to a second embodiment, Fig. 4 illustrates the method for manufacturing a sealing element with a desired cross-section according to a third embodiment, Fig. 5 illustrates the method for manufacturing a sealing element with a desired cross-section according to a fourth embodiment, Fig. 6a shows a perspective view of a sealing element with a desired cross-section, Fig. Figure 6b shows a cross-section of a first example of a sealing element with a desired cross-section, Fig. Figure 6c shows a cross-section of a second example of a sealing element with a desired cross-section, and Fig. Figure 6d shows further examples of possible cross-sections of a sealing element.

[0034] The following describes in more detail the method for manufacturing a sealing element for a caliper brake based on the attached figures, in which the same reference numerals refer to the same elements.

[0035] The Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5 illustrate the process for manufacturing a sealing element 1 schematically in a cross-sectional profile.

[0036] In particular, illustrates Fig. 1. The conventional method for manufacturing ring-shaped sealing elements. Fig. 2 and Fig. Figure 3 then illustrates embodiments of the method in which, similar to the conventional method, a sealing blank is first cut from a hose made of an elastic material and then radially expanded.

[0037] Fig. Figure 1 illustrates the conventional method for manufacturing an annular sealing element. A tube 3 made of an elastic material is positioned around a mounting core 4. The tube 3 and the mounting core 4 rotate together around an axis A. A cutting tool 5 is able to move perpendicular to the axis A to cut sections of a defined width from the tube 3. These sections form the sealing elements 1, which, as a result of this conventional method, have a rectangular cross-section. As can be seen, this conventional process is relatively simple and requires only a few tools. Consequently, it is preferable to produce sealing elements 1 with a desired cross-section in a similarly simple manner.

[0038] In the proposed method for manufacturing sealing elements for a caliper brake with a desired cross-section, the conventional method of manufacturing sealing elements can be taken as a starting point: To produce annular sealing blanks 2, a cutting tool 5 cuts parts from a tube 3 made of an elastic material, supplied around a mounting core 4. This first step S1 of supplying sealing blanks 2 by cutting ring elements 2 of a defined width from a tube 3 is in Fig. 2 and Fig. 3 shown.

[0039] Fig. Figure 2 further illustrates a first embodiment of the method in which the sealing blank 2 is radially expanded at both its inner and outer diameters for further processing. Here, the sealing blank 2 is a ring element 2 and has an inner diameter Di, an outer diameter Do, a width b, and a thickness a. In the second step S2, the sealing blank 2 is then radially expanded by expanding the mounting core 4 to the inner diameter Di+d. This deforms the material of the sealing blank 2, resulting in a reduced thickness a1 and an increased width b1. This pre-loading later enables the sealing element 1 to exhibit the desired properties with respect to the desired sealing characteristics and elastic deformation, with the desired cross-section. It also allows for improved machinability in the next step.

[0040] In step S3, a second cutting tool 6 is used to cut chamfers into the inner and outer diameter edges of the sealing blank 2. This is performed while the sealing blank 2 is radially expanded. The chamfers are provided with the required angles and depths, resulting in the desired cross-section when the preload on the sealing blank 2 is released. Such chamfer cutting enables the production of a wide variety of complex projections on the axial side surface of the sealing element 1.

[0041] As illustrated here, the second cutting tool 6 can be a novel tool configured to cut all four edges of the gasket blank 2 simultaneously. Rotation about axis A allows the second cutting tool 6 to cut chamfers along the entire circumference of the gasket blank 2. The second cutting tool 6 can be identical to the first cutting tool 5, or both can be components of a larger machine tool. The cutting tools 5 and 6 can be controlled by a CNC machine to automate the process and enable a wide variety of cutting patterns. The cutting step S3 can also include surface treatments performed on the inner and outer diameters of the gasket blank 2 to improve certain material properties, such as surface hardness or coefficient of friction.

[0042] In step S4, the sealing blank 2 can relax back to its original diameter Di by removing the retaining core 4. Accordingly, the chamfered material also relaxes into a new geometry, forming the desired cross-section, which is shown here with protrusions on the axial surfaces. A perspective cross-section of the completed sealing element 1 is shown on the right, illustrating how the desired cross-section extends along the circumference of the sealing element 1.

[0043] Fig. Figure 3 illustrates an alternative embodiment of the method in which the sealing blank 2 is only radially expanded at its outer diameter. For this purpose, a vacuum device 7 is used in the second step S2. The vacuum device 7 is attached to the outer circumference of the sealing blank 2 and expands the outer diameter to the new outer diameter Do+t, while not significantly altering the inner diameter. Accordingly, the material of the sealing blank 2 deforms, resulting in an increased thickness a1 but a reduced width b2.It should be noted that, due to the one-sided force applied to the sealing blank 2, this process does not result in a constant deformation of the sealing blank in the radial direction, but rather leads to the width remaining constant at both the inner and outer diameters, and the central area of ​​the sealing blank shrinking due to the expansion caused by the applied vacuum, resulting in concave axial side surfaces.

[0044] In the third step S3, a second cutting tool 6, which simply comprises two knives, can then be used to cut the sealing blank, so that material is removed from the inner and outer diameters of the sealing blank, but the deformed central area remains essentially uncut, as shown in the inserted figure.

[0045] When the material is allowed to relax in the fourth step S4, the deformation reverses, resulting in a convex surface on the axial side face of the sealing element 1, formed by the uncut material in the central region. This embodiment of the method thus enables the very simple creation of convex surfaces. To the right of step S4, a perspective cross-section of the completed sealing element 1 is shown, illustrating how the desired cross-section extends along the circumference of the sealing element 1.

[0046] While the second embodiment only requires that the second cutting tool 6 comprises two blades positioned at a certain distance from each other, it should be obvious that the cutting process can also be carried out with the novel cutting tool 6, as in Fig. The process shown in Figure 2 can be carried out as long as the tool is configured to function under the applied vacuum. It should also be noted that the second cutting tool 6 can be identical to the first cutting tool 5, or both can be components of a larger machine tool. The cutting tools 5 and 6 can also be controlled by a CNC machine to allow for greater degrees of automation. The cutting step S3 can also include surface treatments performed on the inner and outer diameters of the sealing blank 2 to improve certain material properties, such as surface hardness or coefficient of friction.

[0047] In contrast to the Fig. 2 and Fig. 3 illustrate the Fig. 4 and Fig. 5 embodiments of the method in which a hose made of elastic material serves as a starting point, which is then widened before being cut as desired.

[0048] Fig. Figure 4 illustrates an embodiment of the method in which the sealing blank 3 is provided as a complete hose 3 which is expanded via a vacuum device 7 before the sealing elements 1 are cut and chamfered from the hose 3 via a combined cutting tool 5, 6.

[0049] Here, a hose 3 made of an elastic material is provided around a mounting core 4 as a sealing blank 3. The sealing blank has an inner diameter Di and an outer diameter Do. In step S2, the complete hose 3 is expanded in a vacuum device 7, which is designed to cover the entire sealing blank 3 and is evacuated from one end (as shown, from the right), but also has an open end (as shown, on the left). The sealing blank 3 and the mounting core 4 thus serve to close the vacuum device 7, but can still be rotated and moved to the left to be processed in the following steps. The sealing blank 3 is radially expanded at its outer circumference to its new outer diameter Do+t. The inner diameter Di remains unaffected by the vacuum.

[0050] In step S3, the expanded sealing blank 3 is moved out of the vacuum device 7 and cut by the combined cutting tool 5, 6 before it can relax back to its original diameter. The cutting tool 5, 6 removes the material from the sealing blank 3, thus cutting both a ring element from the molded part 3 and the chamfers on the inner and outer diameters of the ring elements. As in Fig. As shown in Figure 4, the cutting tool 5, 6 can cut several ring elements and chamfers simultaneously. Due to the deformation of the material caused by the radial expansion of the sealing blank 3, material is removed unevenly from the axial surfaces of the ring elements.

[0051] If the material can relax in step S4, the deformation consequently reverses, resulting in a convex surface on the axial side face of the sealing element 1. A perspective cross-section of the completed sealing element 1 is shown to the right of step S4.

[0052] Fig. Figure 5 illustrates an embodiment of the method in which the complete hose 3 is expanded by rotation applied by centrifugal force with attached additional masses 8 before the sealing elements 1 are cut and chamfered from the hose 3 by means of a combined cutting tool 5, 6.

[0053] Here, a hose 3 made of an elastic material is again provided around a mounting core 4 as a sealing blank 3. The sealing blank has an inner diameter Di and an outer diameter Do. In step S2, additional masses 8 are attached to the sealing blank 3. The additional masses 8 can be attached directly to the sealing blank 3 or can be, as in Fig. Figure 5 shows that the sealing blank 3 is part of a centrifugal drum, which may further include additional support elements and flywheels. The additional masses 8 can rotate around the axis of the mounting core 4 in the same or opposite direction to the sealing blank 3, thus providing a centrifugal force that expands the sealing blank 3 at its outer diameter. The sealing blank 3 is expanded radially to its new outer diameter Do+t. The inner diameter Di remains largely unchanged.

[0054] In step S3, the expanded sealing blank 3 is cut by the combined cutting tool 5, 6 before it can relax back to its original diameter. The cutting tool 5, 6 removes material from the sealing blank 3, thereby cutting both a ring element from the molded part 3 and the chamfers on the inner and outer diameters of the ring elements. As in Fig. As shown in Figure 4, the cutting tool 5, 6 can cut several ring elements and chamfers simultaneously. Due to the deformation of the material caused by the radial expansion of the sealing blank 3, material is removed unevenly from the axial surfaces of the ring elements.

[0055] If the material can relax in step S4, the deformation consequently reverses, resulting in a convex surface on the axial side face of the sealing element 1. A perspective cross-section of the completed sealing element 1 is shown to the right of step S4.

[0056] While the Fig. 4 and Fig. Figure 5 shows a hose 3 serving as a sealing blank in combination with the widening of the outer diameter of the sealing blank 3 by means of vacuum and centrifugal forces; it is understood that the widening of the inner and outer diameter of the sealing blank 3, as in the embodiment of Fig. As shown in Figure 2, this can also be applied to the entire hose. Similarly, the expansion can be achieved via centrifugal forces, as shown in Figure 2. Fig. Figure 5 shows that, instead of a full hose 3, it can also be applied to a ring element sealing blank 2. While the Fig. 4 and Fig. 5 a combined cutting tool 5, 6 which can cut and chamfer several sealing blanks at once, the illustrated embodiments of the method can also be carried out with the first and second cutting tools 5 and 6, similar to those described in the Fig. 2 and Fig. 3 are shown.

[0057] The Fig. Figures 6a to 6d illustrate the various sealing elements 1 that can be obtained by the proposed method.

[0058] Fig. Figure 6a is a perspective view of the sealing element 1. The sealing element 1 is provided with a number of projections along its circumference on its axial side surface. As shown in Fig. As can be seen in Figure 4a, the desired cross-section can vary along the circumference of the sealing element, since the protrusions are not provided along the entire circumference, but rather with flat surfaces between them. According to the Fig. 2 and Fig. These flat surfaces can be achieved by removing additional material in the 3 processes described.

[0059] The Fig. 6b and Fig. Figure 6c again shows the perspective cross-sections of the last steps of the Fig. 2 and Fig. 3. Fig. Figure 4b shows a sealing element 1 with projections extending along the circumference of the sealing element 1. The cross-section of the sealing element 1 is most easily achieved by the first embodiment of the proposed method, which refers to Fig. 2 was described. Fig. Figure 4c shows a sealing element 1 with convex side surfaces extending along the circumference of the sealing element 1. The cross-section of the sealing element 1 is most easily achieved by the second embodiment of the proposed method, which refers to Fig. 3 was described.

[0060] In Fig.Figure 6d lists further examples of possible cross-sections that can be achieved with the proposed method. Projections can be formed by cutting chamfers in the edges of a sealing blank 2. Convex surfaces can be formed by cutting undeformed edges and allowing the deformed, uncut material to relax. These two processes can, of course, also be combined to produce more complex cross-sections. The two outermost examples on the right can be achieved by machining only one axial side of the sealing blank 2, such that one axial surface has a smaller thickness in the radial direction than the other axial surface. The examples shown are not exhaustive and serve only to illustrate the wide variety of cross-sections that can be achieved with the proposed method.

[0061] As this description makes clear, the method for manufacturing a sealing element for a caliper brake allows for the achievement of a wide variety of cross-sections in a simple and cost-effective manner. Consequently, the method also enables the production of an improved caliper brake in a way that facilitates industrial-scale manufacturing.

[0062] The examples described here are not limiting. In particular, the features of these examples can be combined to achieve additional effects. It is obvious to a person skilled in the art that modifications can be made to these examples without departing from the fundamental principles of the subject matter of this patent application, the scope of which is defined in the claims.

Claims

[1] Method for manufacturing a sealing element (1) for a caliper brake, wherein the sealing element (1) has a ring shape with a desired cross-section, comprising the following steps: Providing (S1) a sealing blank (2, 3) around a fastening core (4), either as a tube (3) or as a ring element (2) of a defined width, cut from a tube (3) by a first cutting tool (5), radial expansion (S2) of the sealing blank (2, 3), Cutting chamfers (S3) on the inner and outer diameter of the sealing blank (2, 3) on at least one axial surface of the sealing blank (2, 3) with a second cutting tool (6) and, if the sealing blank (2, 3) is provided as a tube (3), cutting the ring element (2) from the tube (3) with a first cutting tool (5), Relaxing (S4) the sealing blank (2) back into its original geometry and removing the fastening core (4), resulting in the sealing element (1) with the desired cross-section, wherein during the step of cutting chamfers (S3) on the inner and outer diameter of the sealing blank (2) additional surface treatments are carried out. [2] Method according to claim 1, wherein the sealing blank (2, 3) is radially expanded at both its inner and outer diameters. [3] Method according to claim 2, wherein the sealing blank (2, 3) is expanded by expanding the fastening core (4). [4] Method according to claim 1, wherein the sealing blank (2, 3) is radially expanded at its outer diameter. [5] Method according to claim 4, wherein the sealing blank (2, 3) is radially expanded by a vacuum device (7). [6] Method according to claim 4, wherein the sealing blank (2, 3) is expanded by centrifugal force applied via additional masses (8) attached to the sealing blank (2). [7] Method according to one of the preceding claims, wherein the second cutting tool (6) allows simultaneous cutting on the inner and outer diameter of the sealing blank (2). [8] Method according to any of the preceding claims, wherein the first cutting tool (5) is the same as the second cutting tool (6), or wherein the second cutting tool (6) comprises the first cutting tool (5). [9] Method according to any of the preceding claims, wherein the step of cutting chamfers (S3) and / or cutting the ring element (2) is controlled by a CNC machine. [10] Method according to one of the preceding claims, wherein the desired cross-section comprises an axial surface of the sealing element (1) with at least one projection. [11] Method according to one of the preceding claims, wherein the desired cross-section comprises a convex shape of an axial surface of the sealing element (1). [12] Method according to one of the preceding claims, wherein the desired cross-section comprises that the sealing element (1) has a smaller thickness in the radial direction on one axial surface than on the other axial surface. [13] Method according to any of the preceding claims, wherein the desired cross-section varies along the circumference of the ring shape of the sealing element (1).

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