Vehicle tyre

Abstract

The invention relates to a vehicle tyre, comprising a tread, shoulder sections, lateral wall sections, and bead sections (5), wherein each bead section (5) has at least two bead cores (6.i) each made of a bead wire (7.i) wound annularly in multiple layers (8) and in the circumferential direction, wherein the at least two bead cores (6.i) lie next to one another in the axial direction (X) and at a distance from one another, and wherein each of the at least two bead cores (6.i) is surrounded by a carcass insert (9.i) made of carcass cords running parallel to one another, wherein the carcass cords each run between the two bead sections (5) at a cord angle of between 30° and 40° in relation to the circumferential direction. According to the invention, the bead wire (7.i) is wound within the respective bead core (6.i) in such a way that the respective bead core (6.i) has a substantially octagonal cross-section.

Description

[0001] 202401021

[0002] 1

[0003] Description

[0004] Vehicle tires

[0005] The invention relates to a vehicle tire according to the preamble of claim 1.

[0006] Conventional vehicle tires can be manufactured in either a bias-ply or radial construction, depending on their load-bearing capacity and application. In bias-ply tires, high stability can be achieved through a specific arrangement of carcass cords in at least one carcass ply that are angled less sharply (than in radial tires) relative to the circumferential direction, as well as through a bead section with at least two bead cores.

[0007] The cross-section of the respective bead cores within the bead sections is typically rectangular or, in some cases, hexagonal, as described, for example, in CN 101072693 B. Within the bead cores, particularly in the case of a hexagonal cross-section, a bead wire is wound in multiple turns to achieve better structural integrity due to the smaller splice area and the associated stress peaks or force peaks. By using only one wound bead wire, the number of stress peaks or force peaks on adjacent components of the vehicle tire is minimized, thus largely preventing damage to these adjacent components.

[0008] Nevertheless, a bead core with a hexagonal or rectangular cross-section can still lead to high forces or stress peaks at the corners or edges of the hexagon or rectangle, which can cause fractures in the carcass cords of the carcass ply at the transitions to the adjacent carcass ply that is routed around the bead core. Also other 202401021

[0009] Two adjacent components of the diagonal tire, for example an adjacent bead core in a bead section with two bead cores, can be damaged by such force or load peaks through the "sharp" edges.

[0010] US 2024 034 101 A1 further describes that for radial tires with a single bead core per bead section and carcass cords angled more sharply, up to 90°, relative to the circumferential direction, which are subject to different loads and have different stability requirements, a cross-section of the bead cores is provided in an approximately octagonal shape.

[0011] US 2020 094 505 A1, US 5'989'374 A, JP 2008254398 A, US 9'138'952 B2, CN 216374079 U, JP-H-09254611 A, JP 4615653 B2, and CN 217532427 U also describe radial tire construction with only one wound bead core per bead section and with an approximately octagonal cross-section of the bead core. These radial tires are subject to different loads than bias-ply tires and have different stability requirements, particularly in the bead section. US 4406317A further describes rounding the edges of the bead cores, which, however, is a complex process.

[0012] The following invention is based on the objective of providing a diagonally constructed vehicle tire that has improved structural integrity, particularly in the bead section.

[0013] This problem is solved by a vehicle tire according to the independent claim. The dependent claims specify preferred embodiments.

[0014] According to the invention, a vehicle tire is provided with a circumferentially running tread strip that extends on both sides of a tire zenith, wherein the tread strip extends axially to both sides over 202401021

[0015] 3. A shoulder section transitions into a sidewall section of the vehicle tire, and the respective sidewall section extends radially inwards to a bead section of the vehicle tire, each bead section comprising at least two bead cores, each consisting of a bead wire of a certain thickness wound in several layers and circumferentially in a ring-shaped manner, wherein the at least two bead cores lie side by side and spaced apart from each other in the axial direction within the respective bead section, and wherein each of the at least two ring-shaped bead cores within the respective bead section is independently encircled or surrounded by at least one carcass ply made of parallel carcass cords, for example by folding the carcass cords back on themselves in a radial direction outwards, thereby surrounding the respective bead core in a loop-like fashion.The carcass cords of each carcass ply run at a cord angle of between 30° and 40°, preferably 35°, relative to the circumferential direction over the two sidewall sections, the shoulder sections, and the tread strip between the two bead sections, thus forming a diagonal tire. The bead wire is wound ring-shaped within the respective bead core in several layers such that the respective bead core has a substantially octagonal cross-section. This means that the wound bead wire is enclosed by a body in the shape of an octagon; that is, the bead wire is located entirely within this octagon and defines the shape and extent of this octagon through its outer contour.

[0016] The invention already achieves the advantage that fewer stress peaks or force peaks act on the carcass cords which are angled relative to the circumferential direction and thus also relative to the circumferentially wound bead wire, since the cross-section of the bead core, with in this case eight corners, is closer to the shape of a circular bead core 202401021

[0017] The octagon is approximated by a shape similar to 4. Unlike a rectangle or hexagon, as used in the prior art for bias-ply tires, the corners of the octagon are less acute and enclose a larger internal angle. The carcass cords resting on this bead at the cord angle are therefore subjected to a lower point load, as the force is distributed across the multiple and less acute corners of the octagon. This reduces the risk of carcass cord breakage and increases the durability and reliability of the tire. The octagonal shape of the bead core thus achieves a balance, or compromise, between ease of manufacturing and the impact on surrounding tire components.

[0018] In particular, the adjacent and spaced bead core, which provides additional stability within the same bead section of a bias-ply tire, can be better protected by the octagonal shape of the bead core. Accordingly, the adjacent bead cores can be aligned so that their respective sides of the octagon lie parallel to each other, or side by side, in such a way that the corners of adjacent bead cores do not pinch the intervening carcass plies at specific points. This prevents localized forces and stress concentrations on both the carcass plies and the bead cores. Therefore, the risk of breakage of the bead cores themselves and the carcass plies is reduced, and the durability and reliability of the vehicle tire are increased.

[0019] According to a further embodiment, the bead wire within the respective bead core comprises a bead wire core, preferably made of steel, and a bead wire sheathing made of a rubber material surrounding the bead wire core. In this way, additional stress peaks can be cushioned, since these can be at least partially absorbed by the softer bead wire sheathing.

[0020] 5

[0021] The bead wire sheathing can also adapt, at least partially, to the adjacent surface.

[0022] Preferably, the respective bead core is further defined by a top surface radially outward, a bottom surface radially inward, an inside surface axially inward, and an outside surface axially outward. These surfaces, together with connecting surfaces, define the octagon that encloses the wound bead wire of the bead core. The bead core height is measured between the top and bottom surfaces, and the bead core width between the inside and outside surfaces. Depending on the type (load, size, application, etc.) of the vehicle tire, the bead core height and width may, for example, be between 14 mm and 22 mm. The cross-section of the respective bead core can thus be clearly defined by appropriate lines or boundaries.

[0023] Preferably, the upper surface length and / or the lower surface length are, for example, between 25% and 80%, preferably between 45% and 80%, of the bead core width, and the inner surface length and / or the outer surface length are between 25% and 75%, preferably between 30% and 60%, of the bead core height. It is also possible for the upper surface length and the lower surface length to be different, or for the inner surface length and the outer surface length to be different.

[0024] Within the octagonal shape, a flexible adaptation of the cross-sectional geometry to the type of vehicle tire, in particular to the intended load or stability requirements, is therefore possible. In this regard, it can preferably also be provided that the bead core height and the bead core width of the respective bead core have an aspect ratio between 1:0.8 and 1:1.2 (H6:B6). Therefore, an aspect ratio can also be specifically tailored to the construction of the respective diagonal-ply vehicle tire, 202401021

[0025] 6 in particular also adapted to the construction of the respective bead section with the at least two cores.

[0026] Preferably, the top and bottom surfaces are parallel to each other and parallel to the axial direction, and / or the inside and outside surfaces are parallel to each other and parallel to the radial direction. This allows for simple production of the wound bead core, as the bead core is produced layer by layer in the radial direction, with each layer being built up axially by a corresponding winding. In this way, the at least two bead cores per bead section can be arranged axially next to each other with a sufficiently large overlap, without the corners causing stress concentrations on the adjacent bead core. The positioning of the at least two bead cores within the bead section can therefore be optimized.

[0027] Preferably, the bead wire is wound within the respective bead core with between 55 and 80 turns, and radially overlapping layers within the bead core are offset from each other by half the wire thickness of the bead wire. This ensures optimal stacking of the individual layers, resulting in good stability and strength of the bead core.

[0028] Preferably, the wire thickness of the bead wire is between 1.5 mm and 2 mm, wherein the bead wire core is, for example, at least 1.2 mm thick and the bead wire sheath is, for example, between 0.1 mm and 0.3 mm thick. With such thicknesses, good stability and an approximately octagonal shape can be achieved.

[0029] Preferably, it is further provided that the at least two bead cores each have a bead wire with identical wire thickness. In this way 202401021

[0030] 7. The adjacent bead cores can be optimally arranged within the same bead section with the octagonal shape and without disturbing influences.

[0031] Preferably, the carcass cords of the respective carcass insert preferably run approximately parallel to each other and each has a cord core, for example made of textile, in particular polyamide or polyester, which is surrounded by a cord sheath, for example made of a rubber material. In this way, the carcass cords that are wrapped around the bead cores can be additionally protected, since the cord sheath, due to its low stiffness, can adapt to the corners of the octagonal bead cores. The remaining angularity of the bead cores can thus be at least partially compensated for by this cord sheath made of the rubber material and, depending on the design, also by the bead wire sheath made of the rubber material, which thus complement each other.

[0032] Additionally, it can be provided that in each bead section, a circumferentially ring-shaped bead flap runs radially between the respective bead cores and the carcass cords of the respective carcass insert. This allows any remaining stress peaks between the carcass cords and the bead cores to be absorbed.

[0033] Preferably, it is further provided that the core diameter of the cord cores is between 1.5mm and 1.7mm, preferably 1.6mm, and the sheathing thickness of the cord sheathing is between 0.15mm and 0.25mm, preferably 0.2mm.

[0034] The drawings show: 202401021

[0035] 8

[0036] Fig. 1 shows a vehicle tire in cross-section;

[0037] Fig. 2 shows a detailed view of a bead section of the vehicle tire according to Fig. 1;

[0038] Fig. 3 shows a detailed view of the carcass insert of the vehicle tire according to Fig. 1; and

[0039] Figs. 4A-4G show different octagonal cross-sections of the bead cores in the bead section according to Fig. 2.

[0040] Figure 1 shows a cross-sectional view of a vehicle tire 1, which has a tread 2 running in a ring around it and extending on both sides over a tire zenith Z of the vehicle tire 1. The tread 2 transitions in the axial direction X and in the transverse direction on both sides via a shoulder section 3 into a sidewall section 4, which extends radially R inwards to a bead section 5, so that a bead section 5 is located on both sides of the tire zenith Z.

[0041] Within each bead section 5, as exemplified in Fig. 2, a number N (N=3 in Fig. 1 and Fig. 2) of bead cores 6i, with i = 1, 2, ... N, are provided, wherein the number N is at least two. The at least two bead cores 6i are spaced apart from each other in the axial direction X within the respective bead section. Each bead core 6i is formed by the ring-shaped winding of a bead wire 7i, with i = 1, 2, ... N, so that several layers 8 extending in the axial direction X are formed around the circumference of the respective bead core 6i, which lie one on top of the other in the radial direction R. The wound bead wire 7.i runs in radially superimposed layers 8 offset by half a wire thickness D7.i of the respective bead wire 7.i, i.e. the windings within a layer 8 are placed in spaces between the windings in 202401021

[0042] 9 of a radially below (radially inwards) or radially above (radially outwards) layer 8 “chambered”.

[0043] In each bead section 5, the bead cores 6.i are each surrounded by at least one carcass ply 9.i, with a central carcass ply 9a of each carcass ply 9.i located at the zenith Z of the vehicle tire 1 and extending axially X to both sides and radially R across the respective sidewall sections 4 into the respective bead section 5. The respective carcass ply 9.i thus extends continuously between the two bead sections 5. In the embodiment shown in Fig. 1 and Fig. 2, with the depicted number N = 3 bead cores 6.i, three superimposed carcass plies 9.1, 9.2, 9.3 are provided.

[0044] In the two bead sections 5, the respective carcass insert 9.i is folded from axially inwards to axially outwards around the respective associated bead core 6.i and folded back onto itself, so that the bead cores 6.i in the respective bead section 5 are enveloped by the respective associated carcass insert 9.i. The carcass insert center section 9a of the respective carcass insert 9.i transitions in the respective bead section 5 into a carcass insert end section 9b, which, as a folded-over area of ​​the respective carcass insert 9.i, is again directed radially outwards towards the respective sidewall sections 4.

[0045] The respective carcass insert 9.i is formed, as schematically shown in Fig. 3, by several carcass cords 10 which run approximately parallel to each other and each have a cord core 10a made of textile, for example polyamide or polyester, which is surrounded by a cord sheath 10b made of a rubber material or a rubber compound, wherein preferably an adhesive system is provided between the cord sheath 10b and the cord core 10a. In the cured state of the vehicle tire 1, the carcass cords 10 run at a cord angle 10c of between 30° and 40°.

[0046] 10 preferably at 35° to the circumferential direction U. Consequently, the vehicle tire 1 is a bias-ply tire. The core diameter 10d of the cord cores 10a is preferably between 1.5 mm and 1.7 mm, preferably 1.6 mm, and the sheathing thickness 10e of the cord sheathing 10b is between 0.15 mm and 0.25 mm, preferably 0.2 mm, resulting in a cord thickness 10f of the carcass cords 10 of between 1.8 mm and 2.2 mm.

[0047] In addition, a bead flap 11 (flipper) is provided in the illustration according to Fig. 1 and Fig. 2, which is located radially below (radially inside) the bead cores 6.i in the respective bead section 5 between these and the carcass cords 10 of the respective carcass insert 9.i.

[0048] As shown in the sectional views in Figures 4A, 4B, 4C, 4D, 4E, 4F, and 4G, the bead cores 6.i can have different cross-sections in the respective bead section 5. In each embodiment, however, the respective bead core 6.i has an approximately octagonal cross-section, i.e., the windings of the respective bead wire 7.i are enclosed in the axial direction X and radial direction R by a polygon with eight vertices E. Such an octagon O enclosing the respective bead core 6.i is bounded by a top surface 12a, which limits the respective bead core 6.i radially outward, a bottom surface 12b, which limits the respective bead core 6.i radially inward, an inner surface 12c, which limits the respective bead core 6.i axially inward, and an outer surface 12d, which limits the respective bead core 6.i axially outward. Furthermore, connecting sides 12e run between the inner side 12c and the upper side 12a respectively.the underside 12b as well as between the outside 12b and the top 12a or the underside 12b, as shown.

[0049] The upper surface 12a and the lower surface 12b preferably run approximately parallel to each other and parallel to the axial direction X, and the inner surface 12c and the outer surface 12d preferably run approximately parallel to each other and parallel to the radial direction R. The connecting sides 12e run 202401021

[0050] 11 angled accordingly, preferably such that the respective

[0051] The bead core 6.i is enclosed by a symmetrically designed octagon 0.

[0052] The bead core height H6 (in the radial direction R) of the respective bead core 6.i is determined by a distance between the top surface 12a and the bottom surface 12b, and the bead core width B6 (in the axial direction X) by a distance between the inner surface 12c and the outer surface 12d. The proportions of the top surface 12a and the bottom surface 12b to the bead core width B6 can vary, with a top surface length L12a and a bottom surface length L12b, for example, being between 25% (longer connecting sides 12e) and 80% (shorter connecting sides 12e), preferably between 45% and 80%, of the bead core width B6. Similarly, the inner side length L12c and the outer side length L12d can be between 25% and 75%, preferably between 30% and 60%, of the bead core height H6. Figures 4A and 4B show exemplary cross-sections with different percentage values.It may also be provided that the top side length L12a and the bottom side length L12b are different, or that the inside side length L12c and the outside side length L12d are different.

[0053] Furthermore, the bead core height H6 and the bead core width B6 of a bead core 6.i can be in an aspect ratio between 1:0.8 and 1:1.125 (H6:B6) to adapt the cross-sectional shape to different loads in the vehicle tire 1, to different stability requirements, or to a specific tire size. Figures 4C to 4G show exemplary octagonal cross-sections with different aspect ratios.

[0054] To achieve such aspect ratios, the following layer sequences can be selected within a bead core 6.i, for example: 7-8-9-8-9-8-9-8-7 windings in the respective layer 8 (from the top 12a to the bottom 12b, as shown in Fig. 4C), resulting in a total of 73 windings within the bead core 6.i with an aspect ratio of 1:1.125 (H6:B6) 202401021

[0055] 12 are present. Alternatively, as shown in Fig. 4D, the following sequence of layers 8 can be provided: 5-6-7 -6-7-6-7-6-5-4 windings in the respective layer 8, so that a total of 59 windings are present within the bead core 6.i with an aspect ratio of 1 :0.8 (H6:B6).

[0056] According to the further alternative in Fig. 4E, a 7-8-9-8-9-8-7-6-5-4 sequence with a total of 71 turns is provided to achieve an aspect ratio of 1:1.02 (H6:B6). In Fig. 4F, a 7-8-9-9-9-9-9-8-7 sequence with a total of 76 turns is provided to achieve an aspect ratio of 1:1.2 (H6:B6). In Fig. 4G, a 5-6-7-7-7-7-6-5-4 sequence with a total of 61 turns is provided to achieve an aspect ratio of 1:0.85 (H6:B6).

[0057] The number of windings is determined primarily based on the load on the respective vehicle tire 1, the stability requirements, and the tire size. The wire thickness D7.i of the respective bead wire 7.i can also play a role. For example, the bead wire 7.i can have a wire thickness D7.i of between 1.5 mm and 2 mm, and can also consist of a steel bead wire core 7a and a rubber wire sheath 7b.

[0058] As shown in Figures 1 and 2, three bead cores 6.i within a bead section 5 are arranged adjacent to each other in the axial direction X such that the inner surfaces 12c and the outer surfaces 12d of adjacent octagonal bead cores 6.i are approximately parallel to each other. The respective carcass inserts 9.i run between them. The inner surfaces 12c and the outer surfaces 12d of adjacent octagonal bead cores 6.i can either completely overlap or be offset from each other. This approximately parallel arrangement prevents two adjacent carcass inserts 9.i from being subjected to point contact between corners E 202401021 in the axial direction X.

[0059] 13 adjacent bead cores 6.i are not squeezed. Rather, approximately the same forces act on the intervening carcass inserts 9.i across the entire area. This avoids peak forces or load peaks, thereby increasing the durability of the bead cores 6.i and also the carcass inserts 9.i.

[0060] Accordingly, the respective bead cores 6.i, due to their octagonal cross-section, at least approximate the rounded shape of the carcass cords 10. The corners E, or edges, between the respective sides 12a, 12b, 12c, 12d are also less pronounced due to the octagonal construction 0, thus reducing the peak forces or loads on the carcass cords 10. This, in turn, increases the durability of the carcass cords 10 while maintaining the stability of the bead cores 6.i. This is further optimized by the bead wire sheath 7b of the respective bead wire 7.i, which is made of a rubber compound and is less rigid than the steel bead wire core 7a. Additional forces can be absorbed via the bead flap 11.

[0061] 202401021

[0062] 14

[0063] Reference symbol list

[0064] 1 vehicle tire

[0065] 2 treads

[0066] 3 Shoulder section

[0067] 4 Side wall section

[0068] 5 bead section

[0069] 6.1 i. Bead core

[0070] 7.1 i. Bead wire

[0071] 7a Bead wire core

[0072] 7b Bead wire sheathing

[0073] 8 layers

[0074] 9.1 i. Carcass insert

[0075] 9a Carcass inserts - central area

[0076] 9b Carcass insert end area

[0077] 10 Carcass cords

[0078] 10a Cord core

[0079] 10b Cord sheathing

[0080] 10c Cord angle

[0081] 10d core diameter

[0082] 10e sheathing thickness

[0083] 10f cord thickness

[0084] 11. Bulge flag

[0085] 12a Top

[0086] 12b Underside

[0087] 12c inside

[0088] 12d outside

[0089] 12e Connection page

[0090] B6 bead core width

[0091] D7.i Wire thickness of the i. bead wire 202401021

[0092] 15

[0093] E corner

[0094] H6 bead core height i index

[0095] L12a Top side length L12b Bottom side length

[0096] L12c Inside length

[0097] L12d outer side length

[0098] N number

[0099] 0 Octagon R radial direction

[0100] U circumferential direction

[0101] X axial direction

[0102] Z Tire zenith

Claims

202401021 16 Patent claims 1. Vehicle tire (1) with a circumferentially (U) circumferential tread (2) extending on both sides of a tire zenith (Z) of the vehicle tire (1), wherein the tread (2) transitions axially (X) on both sides via a shoulder section (3) into a sidewall section (4) and the respective sidewall section (4) extends radially (R) inwards to a bead section (5) of the vehicle tire (1), wherein each bead section (5) has at least two bead cores (6.i) each made of a bead wire (7.i) of a wire thickness (D7.i) wound in several layers (8) and circumferentially (U), wherein the at least two bead cores (6.i) lie side by side and spaced apart from each other within the respective bead section (5) in the axial direction (X) and wherein each of the at least two bead cores (6.i)i) within the respective bead section (5) are each independently encircled by at least one carcass insert (9.i) made of parallel carcass cords (10), wherein the carcass cords (10) of the respective carcass insert (9.i) each run at a cord angle (10c) of between 30° and 40° relative to the circumferential direction (U) between the two bead sections (5), characterized in that the bead wire (7.i) is wound within the respective bead core (6.i) such that the respective bead core (6.i) has a substantially octagonal cross-section.

2. Vehicle tire (1 ) according to claim 1 , characterized in that the bead wire (7. i) within the respective bead core (6. i) comprises a bead wire core (7a), preferably made of steel, and a bead wire sheathing (7b) made of a rubber material surrounding the bead wire core (7a). 202401021 17 3. Vehicle tire (1) according to claim 1 or 2, characterized in that the respective bead core (6.i) is bounded radially outward by a top surface (12a), radially inward by a bottom surface (12b), axially inward by an inside surface (12c) and axially outward by an outside surface (12d), which together with connecting sides (12e) define an octagon (O) that surrounds the wound bead wire (7.i) of the bead core (6.i), wherein a bead core height (H6) is measured between the top surface (12a) and the bottom surface (12b) and a bead core width (B6) is measured between the inside surface (12c) and the outside surface (12d).

4. Vehicle tire (1) according to claim 3, characterized in that a top surface length (L12a) of the top surface (12a) and / or a bottom surface length (L12b) of the bottom surface (12b) is, for example, between 25% and 80%, preferably between 45% and 80%, of the bead core width (B6), and an inside surface length (L12c) of the inside surface (12c) and / or an outside surface length (L12d) of the outside surface (12d) is between 25% and 75%, preferably between 30% and 60%, of the bead core height (H6).

5. Vehicle tire (1 ) according to claim 3 or 4, characterized in that the bead core height (H6) and the bead core width (B6) of the respective bead core (6.i) are in an aspect ratio of between 1 :0.8 and 1 :1 ,2 (H6:B6).

6. Vehicle tire (1) according to one of claims 3 to 5, characterized in that the upper surface (12a) and the lower surface (12b) are parallel to each other and parallel to the axial direction (X) and / or the inner surface (12c) and the outer surface (12d) are parallel to each other and parallel to the 202401021 18 run in radial direction (R).

7. Vehicle tire (1 ) according to one of claims 3 to 6, characterized in that the bead wire (7. i) is wound within the respective bead core (6. i) with between 55 and 80 turns and in radial direction (R) superimposed layers (8) are offset from each other by half the wire thickness (D7.i) of the bead wire (7. i).

8. Vehicle tire (1 ) according to one of the preceding claims, characterized in that the wire thickness (D7.i) of the bead wire (7.i) is between 1.5mm and 2mm.

9. Vehicle tire (1 ) according to one of the preceding claims, characterized in that the at least two bead cores (6.i) each have a bead wire (7.i) with identical wire thickness (D7.i).

10. Vehicle tire (1 ) according to one of the preceding claims, characterized in that in the respective bead section (5) in the radial direction (R) between the respective bead cores (6.i) and the carcass cords (10) of the respective carcass insert (9.i) a circumferentially circumferential bead flap (11 ) runs in the circumferential direction (U).

11. Vehicle tire (1) according to one of the preceding claims, characterized in that the carcass cords (10) of the respective carcass insert (9. i) preferably run approximately parallel to each other and each have a cord core (10a), for example made of textile, in particular of polyamide or polyester, which is surrounded by a cord sheathing (10b), for example made of a rubber material. 202401021 19 12. Vehicle tire (1) according to claim 11, characterized in that a core diameter (1Od) of the cord cores (1Oa) is between 1.5 mm and 1.7 mm, preferably 1.6 mm, and a casing thickness (10e) of the cord- The sheathing (10b) is between 0.15mm and 0.25mm, preferably 0.2mm.

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