Manufacturing method of sealing ring and sealing ring

Abstract

The invention relates to a sealing ring (10) for a sealing system (200), in particular a sealing system in the form of a pneumatic or hydraulic system, comprising a sealing edge (52) arranged on the circumferential side for dynamically contacting a sealing surface (40) of a machine part (32, 34), the sealing edge being designed to be annularly closed relative to a central axis (16) of the sealing ring (10), wherein the sealing ring (10) in the unloaded state has a transverse axis (18) in a cross section including the central axis (16), which forms an angle α of 7°≤α≤90° with the central axis (16). The invention also relates to a sealing system and a method for producing a sealing ring (10) from a longitudinal profile (12).

Description

Technical Field

[0001] The invention relates to a method for producing a sealing ring and a sealing ring. Background Art

[0002] Sealing systems are used in many technical fields and are mainly composed of two machine parts, which are spaced apart and can move relative to each other along and / or around an axis of motion. In the case of hydraulic or pneumatic systems, one of the machine parts is designed as a piston or piston rod, and the other machine part is designed as a cylinder in which the piston or piston rod can move back and forth. A bearing or sealing gap is formed between the two machine parts, which is sealed by at least one sealing ring. Alternatively, the sealing system can also have a shaft-shaped machine part and another shell-shaped machine part surrounding the shaft. The sealing ring used usually has a sealing edge, which in its assembly position rests on the sealing surface of one of the two machine parts in a dynamically sealed manner and is usually designed as a so-called radial sealing ring. The sealing ring is held by a seal holding structure, which is usually an annular groove, in which or on which the sealing ring is held. A preload element, such as a rubber ring, is usually used to ensure sufficient contact pressure between the sealing edge and the sealing surface of the sealing ring. The sealing ring can also be designed as a so-called scraper or have a scraper function to prevent water or dirt from entering or being brought into the sealing system.

[0003] Sealing systems with the above-mentioned sealing rings are known, for example, from US 2019 0107 203 A1 and US 5 082295 A.

[0004] Known sealing rings are usually produced by an injection molding process. Summary of the invention

[0005] The object of the present invention is to provide a simplified and cost-effective method for producing a sealing ring having sectionally different material properties and such a sealing ring.

[0006] The object associated with the method for producing a sealing ring is achieved by the method specified in claim 1. Claim 5 specifies a sealing ring according to the invention.

[0007] The method of the present invention is used to manufacture a sealing ring, especially a radial sealing ring, and the method steps are as follows:

[0008] In a first step, a longitudinal profile in the form of a cylindrical tube or a cylindrical rod (solid profile) is provided.

[0009] In a further step, a radial sealing ring to be separated from the longitudinal profile is defined in the material of the longitudinal profile, the transverse axis of the radial shaft sealing ring being at an acute angle α of 7°≤α≤90° with the center axis of the longitudinal profile. In other words, the sealing ring is defined in the material of the longitudinal profile, as seen in the longitudinal section of the longitudinal profile, with its transverse axis extending obliquely to the inner circumferential side of the longitudinal profile. As a result, the outer contour of the sealing ring tapers in the direction of the center axis towards the high-pressure side of the sealing ring.

[0010] In a subsequent step, the sealing ring is separated from the longitudinal profile by machining (or cutting). Conventional machine tools can be used for this purpose.

[0011] Radial sealing rings are usually asymmetrical and have an upstream side facing the high-pressure side H and a downstream side facing away from the high-pressure side H or, in the case of a scraper ring, a side facing the environment. Such radial sealing rings usually need to have different characteristics in the axial width of the sealing surface. For example, radial sealing rings for high-pressure applications require increased mechanical strength on the downstream side, i.e. the low-pressure side. Correspondingly, in the case of scrapers, it is also necessary to increase the hardness of the material facing the environment. Current designs, even if they are made of mixed materials with concentric layers, cannot meet these requirements in one component and therefore often have to include additional components, such as corner reinforcements or support rings for this purpose, which increases complexity and manufacturing costs.

[0012] According to the invention, multi-component longitudinal profiles or hybrid longitudinal profiles with two or more concentric material layers are used as longitudinal profiles, which differ from one another in their material properties (such as mechanical, chemical or electrical properties) or in their cost or appearance. In this respect, longitudinal profiles made of concentric layers of different PTFE (polytetrafluoroethylene) compounds, PTFE / PEEK (=polyetheretherketone) layers or mixed materials of PTFE and PU (polyurethane) layers are particularly suitable.

[0013] Thus, when using multi-component longitudinal profiles, the invention makes it possible to place certain material layers at different axial positions of the sealing ring. This makes it possible to produce parts with different optical, mechanical, electrical or chemical or other material properties in the axial extension of the sealing ring (relative to its center axis). Taking a radial sealing ring used as a piston rod seal as an example, for example, a mechanically loadable material can be provided on the sealing section or sealing edge facing away from the low-pressure side of the seal, while a softer material with better sealing properties can be used in the axial center of the sealing section. If necessary, another material can also be used on the high-pressure side of the radial sealing ring, for example to reduce material costs or improve installation. Similar advantages can also be achieved in other radial seals, radial shaft seals, scrapers, etc.

[0014] The sealing ring produced using the method according to the invention is particularly suitable for hydraulic or pneumatic applications, i.e. pneumatic or hydraulic systems, or as a radial shaft seal. For this purpose, the sealing ring has a sealing edge, preferably a sealing edge arranged on the circumferential side, for dynamic sealing contact with the sealing surface of the machine part. The sealing edge is annularly closed relative to the central axis of the sealing ring. In particular, the sealing ring can be designed as an internal seal or an external seal. According to the invention, in the unloaded state, the sealing ring has a transverse axis on a cross section including the central axis, which forms an acute angle α of 7°≤α≤90° with the central axis of the sealing ring. In this case, the transverse axis refers to the following axis of the sealing ring, which is oriented in the above-mentioned cross section of the sealing ring from the low-pressure side to the high-pressure side and extends parallel to or substantially parallel to the sealing surface or the axis of movement of the machine parts to be sealed from each other in the installed state of the sealing ring. In particular, the transverse axis can be arranged to extend orthogonally to one or both flanks of the sealing ring. Therefore, in the unloaded state, the sealing ring according to the invention has an internal cross section, the size of which decreases from the low-pressure side to the high-pressure side of the sealing ring. Therefore, for installation, the sealing ring must be deformed more on the high-pressure side than on the low-pressure side (i.e., it must be strongly expanded more in the case of an internally sealing sealing ring or compressed more in the case of an externally sealing sealing ring). As a result, the amount of compression over the entire axial width of the sealing ring (over its circumference) changes in the installed or assembled state. This can be used to improve the contact pressure distribution of the sealing ring on the sealing surface (matching surface) in the installed or assembled state of the sealing ring, while improving the resistance to the operating pressure on the high-pressure side H by reducing the load on the low-pressure side section of the sealing ring.

[0015] The sealing ring according to the invention can be produced in a simple and cost-effective manner and no special tools are required for its production.

[0016] According to the invention, the sealing ring can be designed in particular as a radial sealing ring. Here, the radial sealing ring can have a supporting structure, which is arranged on the high-pressure side H of the sealing edge and keeps a certain distance from the sealing edge in the axial direction of the center axis of the sealing ring. Therefore, on the one hand, this means that when assembling the sealing system, when the parts to be sealed to each other are pushed together, the first impact of the machine parts with sealing surfaces of the sealing system on the radial sealing ring can be absorbed. During the assembly process, the supporting structure can also be used to center the radial sealing ring relative to the movement axis of the machine parts to be sealed to each other in the sealing system. Therefore, when the sealing edge contacts the relevant machine parts, it can be contacted circumferentially. This provides a particularly gentle assembly advantage for the sealing edge of the radial sealing ring. Therefore, undesirable structural overstressing of the sealing edge and the associated premature wear or premature functional failure of the radial sealing ring can be prevented. In addition, for example, in the radial internal seal design of a radial sealing ring, when a machine component with a sealing surface is axially inserted into the radial sealing ring on the high-pressure side via a support structure supported on the machine component - before contacting the sealing edge - a torque can be applied to the radial sealing ring, which can cause the radial sealing ring to rotate or swing to or toward its predetermined installation position in / on the seal retaining structure.

[0017] For the sealing performance of the radial sealing ring, it is important that the support structure does not affect the sealing function during operation, nor does it restrict the flow of fluid or pressure into the sealing surface. Therefore, the support structure can have an axially extending wedge. When the radial sealing ring is in use, the support structure preferably does not contact the sealing surface, that is, it maintains a certain distance from the sealing surface.

[0018] According to the present invention, the supporting structure can be formed, for example, by an annular flange, or by a plurality of radial protrusions spaced apart from each other in the circumferential direction of the radial sealing ring, or by the edge of the radial sealing ring, which is formed by the end face / flank of the sealing ring on the assembly opening side or the high-pressure side and the circumferential surface of the sealing ring having a sealing edge.

[0019] According to a particularly preferred development, the radial sealing ring has a circumferential side or side facing away from the sealing edge, which is cylindrical at least in sections in the pressure-loaded installed state of the sealing ring. This makes it possible to achieve a large-area support of a preload ring that is tensioned in the radial direction, by means of which the sealing edge of the radial sealing ring (in the installed state) can be tensioned on the sealing surface of the machine part in the radial direction relative to the center axis of the radial sealing ring. According to another embodiment, the circumferential side can be curved concavely or convexly outwards in the longitudinal direction of the radial sealing ring.

[0020] Particularly preferably, the sealing ring has end sides extending parallel to each other. This allows for simple production and wide application of the sealing ring.

[0021] The sealing ring is designed as a multi-component component, in particular a two-component or three-component component. As a result, the sealing ring can have different material properties in different sections or on different sections as required. For example, the material of the sealing ring can be viscoplastic in the area of ​​the sealing edge, while the remaining part can be rubber-elastic, or vice versa. In addition, the sealing ring can also have a reinforced area, by which the mechanical stability of the sealing ring against deformation is locally improved. If the sealing ring is designed as a multi-component component, then in the unloaded state of the sealing ring, each dividing line between the sealing ring material layers is arranged to extend parallel to the central axis of the sealing ring. In the installed state of the sealing ring, each dividing line forms the above-mentioned acute angle α or substantially forms the above-mentioned acute angle α with the central axis or the axis of movement of the machine part to be sealed, wherein 7°≤α≤90°.

[0022] According to an extension of the present invention, the sealing ring is made of one or more plastics, and the material properties of these plastics are different. For example, at least one of the plastics can be an elastomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other advantages of the present invention are derived from the description and the drawings. The present invention will be explained in more detail below with reference to the embodiments shown in the drawings. The embodiments shown and described should not be understood as exhaustive, but rather as exemplary features for describing the present invention.

[0024] In the attached figure:

[0025] Figure 1 A longitudinal profile is shown in a partial longitudinal section with an exemplary profile of a sealing ring produced by the longitudinal profile, wherein the profile is defined in a conventional manner in the longitudinal profile (prior art);

[0026] Figure 2 A longitudinal profile is shown in a partial longitudinal section with an exemplary profile of a sealing ring produced by the longitudinal profile, wherein the profile is defined in the longitudinal profile in the manner according to the invention;

[0027] Figure 3 A block diagram is shown having a method for manufacturing a device according to the present invention. Figures 1 to 5 The various method steps of the sealing ring;

[0028] FIG. 4 shows a sealing system with a sealing ring arranged in chronological order according to the individual assembly steps of the sealing system, i.e., a first machine part is inserted into a second machine part, the sealing ring is partially pre-installed in the seal retaining structure of the second machine part ( Figure 4A ); The first machine part makes initial contact with the partially installed seal ring ( Figure 4B ), the sealing ring is radially screwed in under the inherent elastic restoring force of the seal and contacts the sealing edge for the first time ( Figure 4C), when the seal ring is further screwed into the seal retaining structure ( Figure 4D ) and when the sealing surface contacts the sealing edge in a non-pressurized assembly state ( Figure 4E );

[0029] Figure 5 The sealing system according to FIG. 4 is shown, with a pressure lower than the maximum operating pressure P applied on the high pressure side. max Operating pressure P;

[0030] Figure 6 The sealing system according to FIG. 4 is shown, with the maximum operating pressure P applied on the high pressure side. max ;

[0031] FIG. 7 shows a cross-sectional view of a sealing ring of a two-component structure ( Fig. 7A ) and the ready-to-install state diagram ( Figure 7B );

[0032] FIG8 shows a cross-sectional view of a sealing ring of a two-component structure ( Fig. 8A ) and the ready-to-install state diagram ( Figure 8B );as well as

[0033] FIG. 9 shows a cross-sectional view of a radial sealing ring in the form of a scraper of a two-component structure ( Fig. 9A ) and the ready-to-install state diagram ( Fig. 9B ). DETAILED DESCRIPTION

[0034] In the prior art, sealing rings and in particular so-called scrapers (which are classified as radial sealing rings) are usually manufactured from longitudinal profiles by injection molding or machining processes. According to the illustration, cylindrical tubes and less frequently rods (solid profiles) are usually used as longitudinal profiles. According to the conventional manufacturing method of sealing rings, the finished sealing ring is defined in the material of the longitudinal profile. Figure 1 In the sectional view of FIG. 1 , example contours of different sealing rings 10 (here purely radial sealing rings are used as an example) are shown in the material of a tubular longitudinal profile 12. The center axis 14 of the longitudinal profile 12 coincides with the center axis 16 of the sealing ring 10 to be produced therefrom. The respective transverse axes 18 of the sealing rings 10 to be produced are oriented so as to extend strictly parallel or substantially parallel to the center axis 16 or the center axis 14 of the longitudinal profile 12.

[0035] The following will combine Figure 2 and Figure 3 The manufacture of the sealing ring 10 (including the radial sealing ring and the scraper) of the present invention is explained. Figure 2 With Figure 1 In a corresponding manner, a section through a longitudinal profile 12 is shown, which includes the contours of the individual sealing rings 10 to be produced from the longitudinal profile 12 according to the method of the invention. Figure 3 A block diagram is shown with the individual method steps of a method 100 according to the present invention.

[0036] According to the method 100 of the invention, in a first step 102, a longitudinal profile 12 is provided. The longitudinal profile 12 can be designed as a cylindrical tube or a cylindrical rod (in particular made of solid material). In the next step 104, as Figure 2 In the figure, the individual sealing rings 10 to be produced are defined in the material of the longitudinal profile 12 by means of exemplary contours of different sealing rings 10 (here purely taking the example of a radially straightened ring). Figure 2 The transverse axis shown in the figure is arranged or defined at an angle α to the center axis 14 of the longitudinal profile 12 or the center axis 16 of the sealing ring 10 to be produced. In principle, the angle α is greater than 7° in magnitude. In particular, the angle α can be between 11° and 90° in magnitude.

[0037] In the next step 106, the sealing ring 10 or the sealing rings 10 are cut (separated) or processed from the longitudinal profile 12 by a machining (or cutting) method. For this purpose, the machining (or cutting) manufacturing methods and machine tools used for the production of seals in the prior art can be used. Therefore, in practice, there is no need for costly new investments.

[0038] according to Figure 2 , compared with the existing technology ( Figure 1 ), the sealing ring 10 manufactured according to the method 100 of the invention has different inner diameters d1, d2 in the region of the respective high-pressure side axial end 20 and the low-pressure side axial end 22. If the sealing ring 10 is to be installed in a seal holding structure, in particular in a (rectangular) groove of a machine component, this can only be achieved if the sealing ring 10 itself is twisted. In other words, a torque must be applied to the sealing ring during installation.

[0039] It should be noted that a multi-component longitudinal profile 12, for example a two-component longitudinal profile 12, can be used as the longitudinal profile 12. Such a longitudinal profile 12 has a multi-layer structure. Therefore, a sealing ring having radial or axial sections 24, 26, the material properties of which are different, can be produced from the multi-component longitudinal profile 12. The individual components or (material) layers 28, 30 of the longitudinal profile 12 shown are arranged coaxially with the center axis 14 of the longitudinal profile 12 and are permanently connected to each other. Therefore, they cannot be separated from each other without destroying the longitudinal profile 12. It is understood that the longitudinal profile 12 can also have more than the two (material) layers shown in the figure.

[0040] The assembly of the sealing system 200 and the sealing ring 10 (here taking the radial sealing ring of the inner seal as an example) at consecutive time points is shown in Fig. 4. For example, the sealing system 200 may be a pneumatic or hydraulic system.

[0041] The sealing system 200 comprises a first machine part 32 and a second machine part 34 which, in the assembled state, are spaced apart from one another, forming a sealing gap 36 , and are arranged to be movable relative to one another along and / or about an axis of movement 38 .

[0042] The first machine part 32 can be, for example, a piston rod. The second machine part can be, for example, a cylinder. The first machine part 32 has a sealing surface 40 and the other machine part 34 has a seal retaining structure 42. The sealing ring 10 is used to seal the high-pressure side H of the system 200 or the sealing gap 36. In the assembled state of the system 200, the sealing ring 10 is retained in the seal retaining structure 42, which is an annular groove (= rectangular groove) with a rectangular cross section here. The sealing ring 10 has a first end side 44 on the high-pressure side and a second end side 46 on the low-pressure side. The inner circumferential side of the sealing ring 10 is marked with 48 and the outer circumferential side is marked with 50. The two end sides 44, 46 of the sealing ring 10 can be implemented to extend parallel to each other.

[0043] In the assembled state, the sealing ring 10 rests with its sealing edge 52 in a dynamically sealing manner on the sealing surface 40 of the first machine part 32. The rubber-elastically deformable preload element 54 serves to ensure a sufficient contact pressure between the sealing edge 52 and the sealing surface 40. The preload element 54 rests on the sealing ring 10 circumferentially and tensions it against the sealing surface 40. For example, the preload element 54 can be designed as a rubber ring or a worm spring.

[0044] Here, one end of the first machine part 32 has a chamfer 56 as an assembly aid. During assembly of the system 200, the first machine part 32 is inserted longitudinally and coaxially to the movement axis 38 from the high-pressure side H into the second machine part 34. Figure 4A In this case, the support structure 58 of the sealing ring 10 first comes into contact with the first machine part 32 in chronological order before the first machine part 32 comes into contact with the sealing edge 52. Figure 4B .

[0045] The sealing ring 10 is moved (by the axial (insertion) movement of the first machine part 32) into the seal holding structure 42 by the first machine part 32 on the high-pressure side with the sealing ring 10 deformed radially, thereby generating a moment 60 on the sealing ring 10. In other words, a radially acting moment is caused by the support structure 58, by which the angle α (see FIG. 4a) is reduced with deformation of the radial sealing ring 10 and the preload element 54 (see FIG. 4c). At the same time, the radial sealing ring 10 and the first machine part 32 are centered relative to the central axis 16 or the axis of movement 38. Overall, this can prevent the sealing edge 52 from being subjected to excessive loads and damage during assembly of the system.

[0046] Only when the first machine part 32 moves further axially into the second machine part 34 will the sealing edge 52 contact the bevel 56 ( Figure 4C ), and due to the further axial movement of the first machine component 32, the seal ring 10 will move further into the seal retaining structure 42 until the sealing edge contacts the sealing surface 40 of the first machine component ( Figure 4D ) and eventually reach Figure 4E The sealing system 200 is shown in the assembled state in a non-pressurized state. Even in this case, the reduction in angle α caused by the assembly still exists.

[0047] It should be noted that in the non-pressurized assembled state of the system 200 , the preload element rests on the sealing ring 10 in such a way that the effective center plane 62 of the preload element 54 is offset in the axial direction toward the high-pressure side H of the sealing ring 10 relative to the sealing edge 52 of the sealing ring 10 .

[0048] exist Figure 5 4, the sealing system 200 is explained above, wherein the operating pressure P of the high pressure side H is P = 1 MPa.

[0049] Figure 6 The maximum operating pressure P of the sealing system 200 on the high pressure side H in this example is shown. max This is the case at 30 MPa.

[0050] according to Figure 5 and Figure 6 , when an operating pressure P is applied to the sealing gap 36 on the high-pressure side, the effective center plane 62 of the preload element 54 is displaced axially toward the low-pressure side N, and the displacement is proportional to the operating pressure P. In this case, the angle α between the transverse axis 18 of the sealing ring 10 and the center axis 16 or the movement axis 38 of the sealing ring 10 is further reduced and even changes its sign. In other words, the parallel orientation of the transverse axis 18 and the center axis can only be achieved in the installed operating state and when the operating pressure P is applied on the high-pressure side.

[0051] At the maximum operating pressure P max hour( Figure 6 ), the preload element is substantially deformed in equal volumes axially toward the low-pressure side N and radially toward the sealing surface 40. Then, the sealing ring 10 rests against the sealing surface 40 with its sealing edge 52 and with its longitudinal section 64 directly adjacent to the sealing edge 52 on the low-pressure side. This allows the sealing ring 10 to be supported over a larger area, thereby preventing undesired damage to the sealing edge 52 of the sealing ring 10 even at higher system pressures. At the same time, the sealing gap 36 has a longer closing distance in the axial direction, which ensures that the sealing ring 10 is in a stable position even at the maximum operating pressure P max It can also ensure sufficient sealing effect.

[0052] Furthermore, the sealing ring 10 may also have a low-pressure-side end section 66 ( Figure 5 ), which tapers (in cross section) at least in sections (e.g. conically) toward the low-pressure end side 46. This occurs when the operating pressure P increases to a maximum operating pressure P max This is conducive to the preload element 54 to produce radial deformation radially along the direction of the sealing surface 40 and generate a tilting moment on the sealing ring 10.

[0053] 7 to 9 show sectional views of the sealing ring 10 ( Fig. 7A , 8A and 9A) and assembly status / operation status ( Figure 7B , 8B and 9B). The sealing rings 10 are each designed as multi-component parts and are cut out from the longitudinal profile in the above-described manner.

[0054] In the unloaded state of the sealing ring 10, the dividing line 68 between the material layers of the sealing ring 10 (see also Figure 2 ) - in the longitudinal section of the radial seal 10 - parallel to the central axis. When the seal ring 10 is fully assembled, it is arranged to be inclined with respect to the central axis 16, respectively. This makes it possible to place a first material (e.g. a material with good sealing and friction properties) on the sealing edge and another material (e.g. a material with high resistance to extrusion of the seal ring 10) on the low-pressure side. As an additional or alternative advantage, this can be used to color characterize the front and back sides of the seal ring 10, thereby improving the installation and inspection procedures.

[0055] According to FIG9 , the sealing ring 10 designed as a scraper has a three-layer structure. Here, the scraping and sealing edge 70 is made of a hard and mechanically strong material, while the sealing edge 52 of the dynamic seal is made of another material, for example a material with good friction properties. Only the areas that come into contact with the preload element or the seal retaining structure can be made of low-cost materials.

Claims

1. A method (100) for manufacturing a sealing ring (10) from a longitudinal profile (12), comprising the following steps: - providing (102) a longitudinal profile (12) in the form of a multi-component tube or multi-component rod, the longitudinal profile having layers (28, 30) which differ from one another in their material properties and which, when viewed in longitudinal section, have a dividing line (68) between the layers (28, 30) which extends parallel to the center axis of the longitudinal profile (12); - spatially defining a sealing ring (10) in the material of the longitudinal profile (12) to be separated from the longitudinal profile (12); and - separating the sealing ring (10) from the longitudinal profile (12) by mechanical processing (106); It is characterized in that The sealing ring to be separated from the longitudinal profile (12) is defined obliquely in the material of the longitudinal profile (12), so that the transverse axis (18) of the sealing ring (10) extends at an angle α relative to the center axis (14) of the longitudinal profile (12) and relative to the dividing line (68), the angle being 7°≤α≤90°.

2. The method (100) according to claim 1, characterized in that: The angle α is selected between 10° and 45°.

3. The method (100) according to claim 1, characterized in that: The angle α is selected between 13° and 30°.

4. The method (200) according to claim 1, characterized in that: The layers (28, 30) are arranged to extend coaxially with respect to a center axis (14) of the multi-component longitudinal profile (12).

5. A sealing ring (10) for a pneumatic or hydraulic system (200), comprising a sealing edge (52) for a sealing surface (40) for dynamically contacting a machine part (32, 34), wherein the sealing edge is implemented as an annular closed shape relative to a central axis (16) of the sealing ring (10), wherein the sealing ring (10) in its unloaded state has a transverse axis (18) in a cross section including the central axis (16), wherein the transverse axis forms an angle α with the central axis (16), wherein the angle is 7°≤α≤90°, and wherein: The sealing ring (10) is produced according to the method (100) of any one of the preceding claims 1 to 4.

Images