SEAL AND METHOD FOR ITS MANUFACTURING

Description

Technical field

[0001] The invention relates to a seal and a method for its manufacture. The seal comprises a spirally wound profile cord made of at least one thermoplastic elastomer material with a retaining element and with at least one sealing lip, which are arranged opposite each other in the radial direction, wherein the profile cord comprises axially adjacent and intersecting helixes and has open end faces on both sides. State of the art

[0002] Such a seal is known from US 6,045,136. The intersecting helices between the two open end faces have a constant pitch, so that the helix formed by the helix has an axial width in the area of ​​the opposing open end faces that is greater by the width of one helix than the axial width of a helix that would consist of a corresponding number of circularly closed helices.

[0003] Compared to the number of its helixes, the previously known seal has comparatively large dimensions in the axial direction and does not essentially completely fill its installation space.

[0004] Another seal of the type mentioned above is known from US 2019 / 0120385 A1. This seal also consists of a spirally helical profile cord comprising axially adjacent and overlapping helixes and having open end faces on both sides.

[0005] Here too, the helix between the open end faces has a constant slope, with the same disadvantages regarding the dimensions in the axial direction that have been described previously.

[0006] Seals and methods for their manufacture are also known, for example from DE 10 2010 051 403 A1.

[0007] The previously known seal is a self-contained sealing ring.

[0008] The sealing ring comprises several sealing profiles arranged axially adjacent to each other, each with at least one sealing lip and at least one hook-shaped connecting claw, which is adjacent to the sealing lip when viewed in cross-section of the respective sealing profile.

[0009] The objective of the known sealing ring is to manufacture it simply and cost-effectively. Furthermore, the sealing ring should be modularly expandable with additional sealing profiles.

[0010] Depending on the specific application, several sealing profiles can be combined to form the sealing ring. The sealing profiles can, for example, be made of multiple components, making them easily adaptable to the specific application. Each sealing profile consists of an elastically flexible material, such as polyurethane.

[0011] In a first process step, a strip-shaped sealing profile is produced and cut to length in a second process step. The cut sealing profile is then formed into a ring shape in a third process step, and the two free ends of the ring-shaped sealing profile are joined together in a fourth process step.

[0012] The sealing profiles can be manufactured, for example, using an extrusion process.

[0013] From DE 27 05 067 A1 a multi-lip seal is known which comprises individual and self-contained sealing rings which are identically designed and are fixed to each other in the axial direction by a snap connection.

[0014] Often, the self-contained sealing rings are installed in their closed state for initial assembly.

[0015] For the replacement of a seal, it is not practical to dismantle structurally complex sealing assemblies, especially those with large dimensions, in a time-consuming and costly manner, simply to replace an old seal with a new one.

[0016] Should a seal need replacing, the previously cut sealing ring is first removed from its installation space in the sealing assembly, and a new, also cut, sealing ring is installed in its installation space, for example, around a shaft of the sealing assembly. Following its installation, this cut new sealing ring must be joined together in a bonding process to prevent leakage during use. Depending on the sealing ring material, this bonding process can be carried out by pinning, gluing, welding, or vulcanizing. Forming tools and / or pins in the cross-section of the sealing ring can be used as aids in this process.

[0017] Both the removal of an old sealing ring and the installation of a new one are therefore undesirably time-consuming and expensive. Description of the invention

[0018] The invention is based on the objective of further developing a seal and a method for its manufacture in such a way that the seal has compact dimensions in the axial direction, essentially fills its installation space completely, and is easy and cost-effective to manufacture. Furthermore, the seal should be easily replaceable in the event of a repair. In particular, the old seal should be easily removed from its installation space and a corresponding new seal installed in the same space, without having to destroy the old seal during removal and without requiring any joining process after the new seal has been installed.

[0019] This problem is solved according to the invention by a seal having the features of claim 1 and by a method having the features of claim 8. The claims relating to it refer to an advantageous embodiment of the seal and to a further development of the method.

[0020] To solve the problem, a seal is provided comprising a spirally wound profile cord made of at least one thermoplastic elastomer material with a retaining element and at least one sealing lip, wherein the retaining element and the sealing lip are arranged opposite each other in the radial direction, wherein the profile cord comprises axially adjacent and intersecting helixes and has open end faces on both sides, and wherein the helixes form a helix pack having a substantially rectangular cross-section, in which the open end faces are each arranged in an imaginary radial plane with the axially adjacent helixes. Preferably, the thermoplastic elastomer material is a TPU.

[0021] An advantage here is that the seal is not designed as a closed sealing ring. Instead, the seal is designed in the form of a conveying spiral to continuously pump the medium to be sealed back into the sealed space during normal use. The medium to be sealed could be, for example, a lubricating medium such as grease or oil.

[0022] It should be noted that the seal according to the invention functions depending on the direction of rotation, for example depending on the direction of rotation of a shaft to be sealed which rotates relative to the seal.

[0023] Because the seal according to the invention is not a self-contained sealing ring, it is particularly suitable for sealing large bearings, for example in wind turbine drives. In such cases, the diameters to be sealed are typically more than 500 mm.

[0024] The helixes form a helical stack with a substantially rectangular cross-section, in which the open end faces are arranged in an imaginary radial plane with the axially adjacent helixes. This design has the advantage that the seal has compact dimensions in the axial direction and essentially fills its installation space completely.

[0025] The axial transformation of the spiralized profile cord into an essentially rectangular helical package takes place at the point on the spiralized profile cord where the open ends of the spiral face each other.

[0026] The offset of the forming process in the axial direction is one profile width of a helix.

[0027] The helixes adjacent to each other in the axial direction are essentially identical in design.

[0028] The helix has, on the one hand, the retaining part in the radial direction and, on the other hand, the sealing lip in the radial direction, wherein the retaining part and the sealing lip each have a substantially constant diameter along the axial direction between the open end faces.

[0029] The seal is used in an installation space of a sealing assembly, where the retaining part is fixed in a housing bore, for example, with a static seal and relatively rotationally fixed against rotation. The housing bore is penetrated by a shaft to be sealed. The sealing lip provides the seal to the shaft.

[0030] The helix can be positively locked to each other on its axially facing sides by a snap connection in both the radial and axial directions. An advantage of this is that the individual helixes of the spiral profile cord cannot shift relative to one another; they are arranged in a relatively fixed position. This results in good performance characteristics over a long service life, particularly a good sealing result. After the spiral profile cord is installed in the installation space of a sealing assembly, the snap connection holds the helix together at the required diameter. The spiral profile cord is installed in all cases, both during initial installation and during subsequent replacement, by inserting it into the installation space of a sealing assembly, first by elastic deformation, and then by snapping the connection into place.

[0031] The spirally coiled profile cord is preferably arranged in its installation space under axial elastic prestress.

[0032] In an initial design, the profile cord can be made of at least one thermoplastic material, and the retaining part and the sealing lip can be integrally formed and made of a single material. This design offers the advantage of simple and cost-effective manufacturing. Furthermore, the seal is recyclable by type after its intended use.

[0033] In another embodiment, the profile cord can be made of two different materials for the retaining element and the sealing lip. The advantage here is that the retaining element and the sealing lip are functionally customized by using materials particularly suitable for the respective application. This ensures that the profile cord is held securely within the installation space by the retaining element, and the sealing lip provides a particularly reliable seal for the machine element to be sealed.

[0034] At least one of the materials can be polyurethane. Such a material has the advantage of being readily thermoplastic. The profile cord is preferably manufactured by extrusion. This process is efficient and cost-effective. Furthermore, polyurethane has good wear resistance and excellent abrasion resistance, high strength, and high elongation at break. The material is resistant to mineral oils over a wide temperature range and exhibits excellent ozone and oxidation resistance. It has good damping properties, very good low-temperature flexibility, and high resistance to cracking; the material also exhibits high tensile strength.

[0035] The method for manufacturing the seal is characterized in that, in a first process step, a spirally wound profile cord is produced, and in a second process step, the spirally wound profile cord is cut to length according to the installation length of an installation space in a sealing arrangement in which the seal is to be used. The profile cord is preferably extruded from thermoplastic polyurethane granules and formed into a sealing profile in a continuous forming process. The sealing profile can have the snap-fit ​​connection described above.

[0036] The manufacturing process is particularly simple. Separate tools, such as those required for vulcanization or polyurethane tube casting, are not necessary.

[0037] All that is required is a tool for a specific geometry of the profile cord, which can then be used for all the required different diameters.

[0038] The process involves plasticizing granules via an extruder and continuously reshaping them using a heated tool.

[0039] In a third process step, the spiraled profile cord can be compressed axially into the essentially rectangular helix pack, whereby in this third process step, the snap connection between the adjacent helixes is simultaneously engaged as part of the axial compression into the helix pack. This completes the production of the ready-to-use seal. Brief description of the drawing

[0040] An embodiment of the seal according to the invention is described below with reference to the Figure 1 and 2 explained in more detail.

[0041] These show, in schematic representation: Figure 1 shows the seal as a single component, with the spirally wound profile cord forming the helix; Figure 2 shows the seal made of Figure 1 , installed in the installation space of a sealing arrangement. Implementation of the invention

[0042] In Figure 1 Figure 1 shows an embodiment of the seal according to the invention. The seal is designed as a conveying spiral and comprises the spiraled profile cord 1 with the retaining part 2 and the sealing lip 3. The retaining part 2 and the sealing lip 3 are arranged opposite each other in the radial direction 4. The profile cord 1 comprises helixes 6 arranged adjacent to each other and intersecting in the axial direction 5 and has open end faces 7, 8 on both ends.

[0043] The helixes 6 form the helix package 10 with a substantially rectangular cross-section. The open end faces 7, 8 are each arranged in an imaginary radial plane 11 with the axially adjacent helixes 6.

[0044] To positively lock the helix 6 of the spiralized profile cord 1 together in radial 4 and axial 5 directions, the snap connection 9 is provided, as shown in Figure 2 shown.

[0045] In Figure 2 A sealing arrangement is shown in which the seal is made of Figure 1 The seal is arranged in an installation space 12 of a housing 13. The seal is arranged in the installation space 12 of the housing 13 under axial preload and is rotationally fixed to the retaining part 2 of the spirally wound profile cord 1 under axial preload. The sealing lip 3 surrounds the machine element 14 to be sealed, here in the form of an outer bearing shell of a rolling bearing, under radial preload.

Claims

1. Seal, comprising a spiralized profiled cord (1) made of at least one thermoplastic elastomer material with a holding part (2) and with at least one sealing lip (3), which are arranged opposite one another in the radial direction (4), wherein the profiled cord (1) comprises coils (6) which are arranged adjacent to one another in the axial direction (5) and merge into one another and have end faces (7, 8) which are open on both sides, characterized in that the coils (6) form a coil assembly (10), which has a substantially rectangular cross section, in which the open end faces (7, 8) are each arranged in an imaginary radial plane (11) with the respective axially adjacently adjoining coils (6).

2. Seal according to claim 1, characterized in that the coils (6) are substantially of the same design.

3. Seal according to one of Claims 1 or 2, characterized in that the coils (6) have the holding part (2) in the radial direction (4) on the one hand and the sealing lip (3) in the radial direction on the other, and in that the holding part (2) and the sealing lip (3) each have a substantially constant diameter along the axial direction (5) between the end faces (7, 8).

4. Seal according to one of Claims 1 to 3, characterized in that the coils (6) are fixed to each other form-fittingly on their axially facing sides by a snap connection (9) in a radial (4) and axial direction (5).

5. Seal according to one of Claims 1 to 4, characterized in that the profiled cord (1) consists of a thermoplastic material, and in that the holding part (2) and the sealing lip (3) merge into one another as a single piece and are formed as a single material.

6. Seal according to one of Claims 1 to 4, characterized in that the profiled cord (1) consists of two different materials for the holding part (2) and sealing lip (3).

7. Seal according to one of Claims 5 or 6, characterized in that at least one of the materials is a polyurethane.

8. Method for producing a seal according to one of Claims 1 to 7, characterized in that in a first method step a spiralized profiled cord (1) is produced, wherein in a second method step the spiralized profiled cord (1) is cut to length in accordance with an installation length of an installation space in a sealing arrangement in which the seal is to be used.

9. Method according to Claim 8, characterized in that in a third method step, the spiralized profiled cord (1) is compressed in an axial direction (5) to form the substantially rectangular coil assembly (10).

10. Method according to Claim 9 for producing a seal according to Claim 4, characterized in that in the third method step, the snap connection (9) between the coils (6) is snapped in at the same time as the axial compression to form the coil assembly (10).