TECHNICAL FIELD OF INVENTION
The invention relates to pneumatic tyres. The invention relates to methods for manufacturing pneumatic tyres.
BACKGROUND OF THE INVENTION
Pneumatic tyres are commonly used in vehicles. Quality of a tyre may be characterised by several factors, including roll resistance, resistance to wear, endurance in general, ability to handle, and aquaplaning, to name a few.
Some of these properties may be improved by using certain types of rubber material, reinforcement structures and/or tread patterns.
SUMMARY OF THE INVENTION
It has been found that many properties, including handling, roll resistance, and endurance, may be improved by stiffening the sidewalls and/or the bead areas of the tyre. Moreover, it has been found that such stiffening may be obtained by arranging the layers of plies in a manner that stiffens these areas. In particular, the plies commonly have a reinforcing cords. By arranging the plies in such a way that, in the bead area, each ply is arranged cross-wise with respect to its neighbouring plies (or a neighbouring ply, when considering the innermost or outermost layer), the layers form a stiff structure at the sidewall. Moreover, the size of such a region should be reasonably large to stiffen the tyre. Moreover, in order to have this region reasonable large and simultaneously using only a relatively small amount of raw materials, the material sizes and locations are specifically selected for the tyre and in a corresponding method for manufacturing.
A method for manufacturing a tyre is disclosed in the independent claim 1. A tyre, having been made by the method, is disclosed in the independent claims 8 and 9.
Preferably embodiments have been disclosed in the dependent claims 2 to 7 and 10 to 15.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows half of a cross section of a tyre, wherein the cross-sectional plane comprises the axis of rotation of the tyre,
FIGS. 2a
1 and 2a2 show winding ply materials onto a carcass drum,
FIG. 2b shows a tubular carcass on the carcass drum,
FIG. 2c shows a cross section of the tubular carcass,
FIG. 2d shows an annular carcass formed by expanding the tubular carcass on the carcass drum, and an annular belt structure on the annular carcass,
FIG. 2e shows a cross section of another tubular carcass,
FIG. 3a shows a bead area and a sidewall of a tyre or an annular carcass according to an embodiment of the invention,
FIG. 3b shows a bead area and a sidewall of a tyre or an annular carcass of a comparative example,
FIG. 3c shows cords of two neighbouring ply layers in a bead area and the sidewall,
FIG. 4a shows a tyre and cords of different plies therein, as seen from above,
FIG. 4b shows the mutual arrangement of ply materials during manufacturing of a tyre with two layers of ply material,
FIG. 4c shows the mutual arrangement of ply materials during manufacturing of a tyre with three layers of ply material,
FIG. 5a shows a bead area and a sidewall of a tyre or an annular carcass with three plies,
FIG. 5b shows a bead area and a sidewall of another tyre or another annular carcass with three plies, and
FIG. 6 shows a bead area and a sidewall of a tyre or an annular carcass with four plies.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross section of a tyre 100. The tyre comprises a carcass 130 having plies 712, 722, and a tyre tread radially surrounding the carcass. The carcass 130 comprises, as an innermost layer, an innerliner 131, typically made of only a polymer. In contrast to the innerliner 131, which is free from cords, the plies 712, 722 comprise cords, as will be detailed below. The tread is arranged to make a rolling contact with ground while driving. The centre of the tyre tread is commonly referred to as the crown area 191.
Referring to FIGS. 2a1 and 2a2, a pneumatic tyre 100 is commonly manufactured by winding first and second ply materials 812 and 822 onto a carcass drum 300 to form the first and second plies 712 and 722, respectively. As indicated in FIG. 2a1, the first ply material 812 and the second ply material 822 may be wound substantially simultaneously. As indicated in FIG. 2a2, the first ply material 812 may be wound onto the and the second ply material 822 after winding the second ply material 822. By said winding, a tubular carcass preform 400 is formed, as indicated in FIG. 2b.
Referring to FIGS. 2b to 2d, two cables 152, 154 are arranged onto the tubular carcass preform 400, and the parts of the tubular carcass preform 400 that are left in between a boundary 402, 404 of the tubular carcass preform 400 and the one of the two cables 152, 154 that is closer to the corresponding boundary 402, 404 of the tubular carcass preform are turned about the closer cable 152, 154 onto the part of the tubular carcass preform 400 that is left in between the two cables 152, 154. Thereafter, the tubular carcass preform 400 is expanded to form an annular carcass 410 (FIG. 2d). An annular belt 450 can be arranged onto the annular carcass 410 to form a preform 460 for a tyre 100 (often referred to as a green tyre). By curing the preform 460 for a tyre, a pneumatic tyre 100 can be manufactured, as known to a skilled person.
Typically, the plies 712, 722 comprise cords extending in a direction forming a small angle with the direction of axis of rotation AX. Moreover, typically the cords of adjacent plies are crossed. Referring to FIG. 3b, a comparative example comprises a wide second ply 722 and a narrow first ply 712, the first ply 712 being arranged, in the tyre, at the crown area 191 (see FIG. 1) outwards from the second ply 722. Thus, the bead area 415 includes a region “RA” having an inner 715 and an outer 716 layer of the first ply material 812 and an inner 725 and an outer 726 layer of the second ply material 822. In addition, the bead area 415 includes a region “RB” having only an inner 715 layer of the first ply material 812 and an inner 725 and an outer 726 layer of the second ply material 822. However, because of the crossing direction of the cords of different plies, in the region “RB”, the cords of the outer layer 726 of the second ply material 822 are substantially parallel with the cords of the inner layer 715 of the first ply material 812. Only in the region “RA”, the cords of the inner 715 and outer 716 layer of the first ply material 812 are crossed relative to each other. Herein, the reference 415 refers to a bead area of a carcass 410, while the references 142, 144 refer to the bead area of a tyre.
It has been found that because of this crossing of cords, the region “RA” is stronger that the region “RB”. Therefore, in an embodiment, the size of the region “RA” is made large in comparison with the size of the region “RB”. In particular in an embodiment, the region “RB” is completely dispensed with.
Referring to FIG. 3a, in an embodiment, the outer layer 716 of the first ply material 812 extends, at a bead area 142, 144, 415 along a sidewall 132, 134 of a pneumatic tyre 100 (or carcass 410) in the outward radial direction+SR, from a boundary 727 of the outer layer 726 of the second ply material 822. In such an embodiment, the region “RB” is completely dispensed with, and the cords of all the plies are arranged cross-wise relative to the cords of all neighbouring plies (one or two, depending on which ply is considered at which location). As a result, the carcass 130 is stiffer, compared to a tyre of a comparative example of FIG. 3b, wherein substantially same amount of materials are used. This improves many properties of a tyre, including handling, roll resistance, and endurance. In particular, by such an arrangement, the stiffness of the tyre increases, whereby the tyre has better driving characteristics and improved wear resistance in general.
This concept is reflected both in a method for manufacturing a part of a tyre (and optionally also the whole tyre), as well as in the resulting tyre itself and/or its intermediated products.
FIGS. 2a
1, 2a2, and 2b to 2d show an embodiment of a method for manufacturing an annular carcass 410 of a pneumatic tyre 100. FIGS. 4a and 4b further clarifies the method. With reference to these figures, the method comprises providing a first web 810 of a first ply material 812, the first web 810 extending in a longitudinal direction SL, having a first width W1 in a transversal direction ST perpendicular to the longitudinal direction SL, and comprising first cords 814 extending in a direction forming a first angle α1 of more than 0 degrees and at most 10 degrees with the transversal direction ST. The first angle α1 may be e.g. from 0.5 to 5 degrees, such as from 1 to 3 degrees. The method comprises providing a second web 820 of a second ply material 822, the second web extending in the longitudinal direction SL, having a second width W2 in the transversal direction ST, and comprising second cords 824 extending in a direction forming a second angle α2 of more than 0 degrees and at most 10 degrees with the transversal direction ST. The second angle α2 may be e.g. from 0.5 to 5 degrees, such as from 1 to 3 degrees. The term “web” here refers to rollable (i.e. windable) material; the cords of the material 812 no not necessarily form a network.
To dispense with the region “RB” (see above) of the bead area, the second width W2, i.e. the width of the web 820 of the second ply material 822 is less than the first width W1, i.e. the width of the web 810 of the first ply material 812 (i.e. W2<W1, see FIG. 4b). In an embodiment, the width of the second ply material 822 (i.e. the second width W2, FIG. 3b) is at least 10 mm less than width of the first ply material 812 (i.e. the first width W1). In other words, in an embodiment, W1−W2≧10 mm. This difference also affects the rigidity of the bead area 142, 144 of the pneumatic tyre 100. Thus, preferably, W1−W2≧20 mm or W1−W2≧30 mm.
Referring to FIGS. 2a1 and 2a2, an embodiment comprises winding at least a layer of the first ply material 812 and a layer of the second ply material 822 onto a carcass drum 300 such that the transversal direction ST is parallel to the axis of rotation AX of the tyre drum 300. Moreover, to dispense with the region “RB” (of FIG. 3b), the first ply material 812 radially surrounds the second ply material 822. Furthermore, to increase the strength, the plies is arranged cross-wise with respect to each other. In other words and with reference to FIGS. 4a and 4b, in a location, the direction to which the second cords 824 of the second ply material 822 extend form a third angle α3 with the direction to which the first cords 814 of the first ply material 812 extend, wherein the third angle α3 is greater than the second angle α2. Moreover, with reference to FIG. 4b, in the direction of the axis of rotation AX (which is parallel to the transversal direction ST), on both sides, the first ply material 812 extends in the direction of the axis of rotation AX outwardly from a boundary 826, 828 of the second ply material 222.
Referring to FIGS. 2b and 2c, by said winding, a tubular carcass preform 400 is manufactured. FIG. 2c indicates, how the first ply material 812 radially surrounds the second ply material 822. In an embodiment, the first ply material 812 is next to the second ply material 822 in the radial direction at the crown area 191. In an embodiment, the first ply material 812 is in contact with the second ply material 822 in such a way that no other material that comprises cords, e.g. other ply material, is arranged in between first ply material 812 and the second ply material 822.
Referring to FIGS. 2a1 and 2a2, the ply materials 812, 822 may be wound in sequence in such a way that the second ply material 822 is wound first, and the first ply material 812 is wound onto the second ply material. In the alternative, both the ply materials may be wound at the same time as a layer comprising both the ply materials. After winding the material, two cables 152, 154 are arranged onto the tubular carcass preform 400.
As indicated above, the ply materials may be provided in the form of a single web, or a web for each ply material, from which pieces of suitable length are cut. In the alternative, the ply material may be provided in the form of pre-cut sheets. In both cases, in tubular carcass preform 400, the first ply material 812 radially surrounds in all locations of the second ply material 822 as indicated in FIGS. 2b and 2c.
The first ply material 812 comprises rubber as a matrix material and first cords 814 integrated with the matrix. The first cords 814 may comprise at least one of cotton, rayon, polyamide (Nylon), polyester, polyethylene terephthalate, and Poly-paraphenylene terephthalamide (Kevlar). The cords reinforce the ply.
The second ply material 822 comprises rubber as a matrix material and the second cords 824 integrated with the matrix. The second cords may comprise at least one of cotton, rayon, polyamide (Nylon), polyester, polyethylene terephthalate, and Poly-paraphenylene terephthalamide (Kevlar). The second cords 824 may be made of from the same material as the first cords 814. The rubber of the second ply material 822 may be the same as the rubber of the first ply material 812.
The part of the tubular carcass preform 400 that is left in between a boundary 402 of the tubular carcass preform 400 and the one 152 of the two cables 152, 154 that is closer to the boundary 402 of the tubular carcass preform is turned about the closer cable 152 onto the part of the tubular carcass preform 400 that is left in between the two cables 152, 154. In this way, the bead area 415 (corresponding to bead area 142 of FIGS. 3a and 1) is formed. Also the part the part of the tubular carcass preform 400 that is left in between a boundary 404 of the tubular carcass preform 400 and the one 154 of the two cables 152, 154 that is closer to the boundary 404 of the tubular carcass preform is turned about the closer cable 154 onto the part of the tubular carcass preform 400 that is left in between the two cables 152, 154. In this way, another bead area 415 (corresponding to the area 144 of FIG. 1) is formed. Referring to FIG. 2d, the tubular carcass preform 400 is expanded to form an annular carcass 410.
The tubular carcass preform 400 may be expanded before the boundary parts of the tubular carcass preform 400 are turned. In the alternative, the tubular carcass preform 400 may be expanded after the boundary parts of the tubular carcass preform 400 are turned. In the alternative, the tubular carcass preform 400 may be expanded substantially simultaneously with the turning of the boundary parts of the tubular carcass preform 400.
FIG. 3a shows a part of an annular carcass 410 manufactured in this way. The carcass 410 of FIG. 3a comprises, in a bead area 415, an inner 715 and an outer 716 layer of the first ply material 812 and an inner 725 and an outer 726 layer of the second ply material 822.
Referring to FIG. 3a, an embodiment comprises using a first ply material 812 having such a width W1 that, in the annular carcass 410, the inner layer 715 of the first ply material 812 makes a contact with an outer layer 716 of the first ply material 812 at all locations of a region RA. Moreover, the first ply material encircles a cable 152. In an embodiment, the region RA extends a first distance d1 along the cylindrical carcass preform 400 in a substantially radial direction, and the first distance d1 is at least 5 mm. The distance may be e.g. at least 10 mm or at least 15 mm. These values ensure a reasonable amount of cords crossing each other at the sidewall of the tyre.
Referring to FIG. 3a, in an embodiment, at a sidewall 132, 133 of a tyre 100, the inner 715 layer of the first ply material 812 makes a contact with an outer 716 layer of the first ply material 812 at each point of an area RA. In an embodiment, the area RA extends in a substantially radial direction a first distance d1. The first distance d1 may be e.g. at least 5 mm, at least 10 mm, or at least 15 mm.
A pneumatic tyre 100 can be made using the annular carcass 410. Referring to FIG. 2d, in an embodiment, an annular belt structure 450 is arranged onto the carcass 410 to form a preform 460 for a tyre. Moreover, as known to a skilled person, the preform 460 for a tyre is cured to form the pneumatic tyre 100 using a curing temperature and time known per se.
A part of a cross section of a pneumatic tyre is shown in FIG. 1. A pneumatic tyre 100 according to an embodiment of the invention can be (and has been) manufactured by the aforementioned method. Referring to FIG. 1, such a tyre 100 has a crown area 191, sidewalls 132, 134, and bead areas 142, 144. As indicated in FIG. 1, the pneumatic tyre 100 comprises a carcass 130. While the carcass 130 of the pneumatic tyre 100 has been cured, the annular carcass 410 is not cured before curing. The carcass 130 of the tyre is made by forming the annular carcass 410 as discussed above, and curing. As indicated above, the pneumatic tyre 100 has the bead area 415 of a corresponding carcass 130, 410. While driving, the tyre 100 is configured to rotate about an axis of rotation AX.
The carcass 130 of the tyre 100 comprises a first ply 712 of first ply material 812 and a second ply 722 of second ply material 822 in such a way, that in the crown area 191, the first ply material 812 radially surrounds the second ply material 822. In the radial direction, the first ply material 812 is next to the second ply material 822. The crown area 191 is depicted in FIGS. 1 and 4a. FIGS. 2c and 2e indicate, how the different ply materials 812, 822, 832, and 842 may surround each other in the carcass preform 400 or in the crown area 191 of the tyre 100. The crown area 191 of the tyre 100 is arranged to make a rolling contact with ground while driving.
The first ply material 812 comprises first cords 814 extending within the first ply material 812 in a first direction that depends on a location within the tyre 100. At a point of the crown area 191, the first direction forms a first angle α1 with the direction of the axis of rotation AX, as indicated in FIG. 4a. The second ply material 822 comprises second cords 824 extending within the second ply material 822 in a second direction that depends on a location within the tyre 100. At the point of the crown area 191, the second direction forms a second angle α2 with the direction of the axis of rotation AX and a third angle α3 with the direction to which the first cords 814 of the first ply material 812 extend at that point. As is implicit, the point refers to a point of the crow area 191 wherein projections of the first cords and projections of the second cords 824 cross each other, when projected onto the surface of the tyre in a radial direction of the tyre.
The first angle α1 is more than 0 degrees and at most 10 degrees. The second angle α2 is more than 0 degrees and at most 10 degrees. Other preferable values for the angles are indicated above. Moreover, the cords are arranged cross-wise relative to each other, i.e. the third angle α3 is greater than the second angle α2.
In an embodiment of a tyre 100, the material of the first ply 812 comprises rubber and first cords 814. In an embodiment, the first cords 814 comprise at least one of cotton, rayon, polyamide (Nylon), polyester, polyethylene terephthalate, and Poly-paraphenylene terephthalamide (Kevlar). In an embodiment of a tyre, the material of the second ply 822 comprises rubber and second cords 824. In an embodiment, the second cords 824 comprise at least one of cotton, rayon, polyamide (Nylon), polyester, polyethylene terephthalate, and Poly-paraphenylene terephthalamide (Kevlar). The second cords 824 may be made of from the same material as the first cords 814. The rubber of the material 822 of the second ply 822 may be the same as the rubber of the material of the first ply 712.
The tyre comprises a first cable 152 arranged in a first bead area 142. The tyre comprises a second cable 154 arranged in a second bead area 144.
Referring to FIG. 3a, in an embodiment, at a sidewall 132 of the tyre 100, the inner 715 layer of the first ply material 812 makes a contact with an outer 716 layer of the first ply material 812 at each point of an area RA, wherein the area RA extends along bead area 142, 144 substantially radially a first distance d1, and the first distance d1 is at least 5 mm. The term “substantially radially” refer to a direction that is parallel to a direction of the bead area 142, 144, and forms smallest angle with the outward radial direction+SR. The first distance d1 may be at least 10 mm or at least 15 mm. When the inner 715 layer of the first ply material 812 makes a contact with the outer 716 layer of the first ply material 812, no other material that comprising cords, e.g. other ply material, is left in between the inner and outer layers (715, 716). Preferably, at the area RA, no material is left in between the inner and outer layers (715, 716).
Referring to FIG. 3a, in both of the bead areas 142, 144, the tyre 100 comprises (i) an inner layer 715 of the first ply material 812, (ii) an outer layer 716 layer of the first ply material 812, (iii) an inner 725 layer of the second ply material 822, and (iv) an outer 726 layer of the second ply material 822. As indicated above, the materials and their sizes are selected in such a way that the outer layer 716 of the first ply material 812 extends, along a sidewall 132, 134 in a substantially outward radial direction+SR, from a boundary 727 of the outer layer 726 of the second ply material 822. The term “a substantially outward radial direction” refer to a direction that is parallel to a direction of the sidewall 132, 134 and forms smallest angle with the outward radial direction +SR.
Referring to FIG. 3a, the outer layer 716 of the first ply material 812 extends a second distance d2 from the boundary 727 of the outer layer 726 of the second ply material 822 along a sidewall 132 in a substantially outward radial direction+SR. This second distance d2 may be substantially equal to half of the difference of the widths, i.e. (W1−W2)/2. As indicated in this way, d2 may be e.g. at least 2 mm, at least 5 mm, at least 10 mm or at least 15 mm.
The strengthening effect of the cross-wise cords of the plies, also at the bead areas 142, 144, 415, may be observed at least when no other cord-comprising material is arranged in between the inner 715 and outer 716 layers of the first ply material 812 (see FIG. 3a). Thus, in an embodiment no such material that comprises cords (e.g. second ply material 822 or other) is arranged in between the inner layer 715 of first ply material 812 and the outer layer 716 of first ply material 812 in the bead area 142, 144, 415.
As evident from the discussion above, the plies extend from the outer side of the carcass 130, via a first cable 152 to the crow area 191, and further via a second cable 154 to the opposite outer side of the carcass 130. Preferably the plies extend continuously, i.e. each one of the plies 810, 820 is an integrated piece of material. As the plies extend in such a manner, in an embodiment the first ply 712 (and first ply material 812) encircles a first cable 152 and a second cable 154. In an embodiment, where the inner 715 and outer 716 layers of the first ply material are in contact, the first ply 712 (and first ply material 812) fully encircles the first cable 152 and the second cable 154. In an embodiment, the first ply 712 (and first ply material 812) extends continuously in between the cables 152, 154.
In the embodiment, also the second ply 722 and second ply material 822 encircles the first cable 152 and the second cable 154. Moreover, the second ply 722 and second ply material 822 encircles the first ply material 812 that is left in between the cable(s) and the second ply. However, since the layers 715, 716 of the first ply material 812 are left in between the layers 725, 726 of the second ply material 822, the second ply 722 and second ply material 822 only partly encircle the cables 152, 154. However, the second ply 722 and second ply material 822 encircle by at least 270 degrees each of the cables 152, 154, when the amount of encircling is observed from a cross section of the tyre 100 or the annular carcass 410 with a plane including the axis of rotation AX (see FIG. 3a). In FIG. 3a, the second ply 722 and second ply material 822 encircles by about 350 degrees the cable 152 (and also the other cable 154, even if not shown in the figure).
As indicated in FIG. 3a, preferably the plies are turned onto the outer side of the carcass 410 or tubular carcass 400. Correspondingly, in an embodiment, the boundary 717 of the first ply material 110 and the boundary 727 of the second ply material 120 are left on the outer side of the carcass 130 or annular carcass 410, as depicted in FIG. 3a. Correspondingly, on the opposite side of the tyre 100 or the annular carcass 410, also the other boundaries of the ply materials are left on the outer side of the carcass 130, as depicted in FIG. 3a. As indicated in FIG. 1, an innerliner 131 may be arranged on the inner side of the carcass 130.
One feature strengthening the tyre is that the cords of all neighbouring ply layers extend cross-wise with respect to each other at all locations (compare FIGS. 3a and 3b). Neighbouring layers refer to the layers of the laminate that are in contact with each other without any other layers of ply material in between them. Referring to FIG. 3a, a bead area (or a tyre 100 or a carcass 410) comprises layers or ply material. At a location, one of these layers is outermost and one is innermost. E.g. at a location, the layer 726 is the outermost layer, while the layer 725 is the innermost layer. At another location, that is free from the outer layer 726, the layer 716 is the outermost layer. Still further, another location, that is free from both the outer layers 726 and 716, the layer 715 is the outermost layer. Such outermost and innermost layers comprise only one neighbouring ply. In addition, some of the layers are intermediate layers in the sense that they comprise two neighbouring layers. Depending on location, in FIG. 3a, (i) the layers 715 and 716 or (ii) only 715, or (iii) none of the layers, may be seen as an intermediate layer.
In an embodiment, at all locations of the bead area 142, 144, 415, each one of the outermost or innermost layers 726, 716, 715, 725 of ply material 212, 222 comprises cords extending in a direction that forms an angle αN with the direction to which the cords of the neighbouring layer (716, 715, 725, 715, respectively) extend. As indicated above, depending on the location, the layer 716 may be seen as an outermost layer or an intermediate layer. For example, in FIG. 3c, when considering the layer 716 as an outermost layer, the cords 814 therein extend in a direction forming an angle of αN with the direction to which the cords 814 of the neighbouring layer 715 extend. The angle αN is more than zero degrees. The angle αN may be e.g. at least 0.5 degrees or at least 1 degree for each pair of layers.
In an embodiment, at all locations of the bead area 142, 144, 415, each one of the intermediate layers 716, 715 of ply material 812 comprises cords extending in a direction that (i) forms an angle αN with the direction to which the cords of a first neighbouring layer (726, 716, respectively) extend and (ii) forms another angle with the direction to which the cords of a second neighbouring layer (715, 725, respectively) extend. For example, in FIG. 3c, when considering the layer 716 as an intermediate layer, the cords 814 therein extend in a direction forming an angle with the direction to which the cords 814 of the neighbouring layer 715 extend. However, at that point, the intermediate layer 716 has also another neighbouring layer, namely the layer 726, as indicated in FIG. 3a. The direction in which the cords 814 of the intermediate layer extend form another angle with the direction to which the cords 824 (see FIG. 4b) of the neighbouring layer 716 extend. To have a proper reinforcing effect of the cords, both the aforementioned angles are more than zero degrees. In an embodiment, both the aforementioned angles are at least 0.5 degrees or at least 1 degree.
As indicated in the Figures, at each location of the carcass 410, in the direction of the thickness of the carcass 410 the carcass 410 comprises layers 715, 716, 725, 726 of ply material. As indicated in the Figures, the layers may comprise only one or two neighbouring layers.
As indicated in particular in FIGS. 3a,5a, and 6, in a preferable embodiment the cords of each such layer (725, 726) of ply material that has only one neighbouring layer (715, 716) of ply material comprises first cords extending, at a location, within the layer (725, 726) in a first direction. Moreover, the cords of a neighbouring layer of the layer (725, 726) of ply material comprises second cords extending, at the location, within the neighbouring layer in a second direction. The second direction forms and angle with the first direction. The angle is preferably at least 0.5 degrees or at least 1 degree.
As indicated in particular in FIGS. 3a,5a, and 6, in the preferable embodiment the cords each such layer (715, 716) of ply material that has only two neighbouring layers of ply material comprises first cords extending, at a location, within first ply material of the layer (715, 716) in a first direction. In FIG. 3a the layers 716 and 725 are neighbouring the layer 715; and the layers 726 and 715 are neighbouring the layer 716. This applies in particular at a sidewall 132, preferably at both sidewalls 132, 134, of the carcass.
Considering only the layer 715, the cords of a first neighbouring layer 716 of the layer 715 of ply material comprises second cords extending, at the location, within the first neighbouring layer in a second direction. Furthermore, the cords of a second neighbouring layer 725 of the layer 715 of ply material comprises third cords extending, at the location, within the second neighbouring layer in a third direction. As indicated in FIG. 3a, at that location, the layer 715 of ply material is arranged, in between the first neighbouring layer 716 and the second neighbouring layer 725. Furthermore, the second direction forms and angle with the first direction; the angle being e.g. at least 0.5 degrees or at least 1 degree. Furthermore, the third direction forms and angle with the first direction; the angle being e.g. at least 0.5 degrees or at least 1 degree. This applies in particular at a sidewall 132, preferably at both sidewalls 132, 134, of the carcass. In addition to FIG. 3a, such embodiments are also depicted in FIGS. 5a and 6.
Referring to FIG. 5a, a tyre 100 and/or an annular carcass may comprise further plies, in particular, a third ply 732 of third ply material 832. Without loss of generality, the first ply 712 may refer to the ply that is, the crow area 191, radially the outermost ply. The second ply 722 may be the one neighbouring the first ply 712. The third ply 732 may be the one neighbouring the second ply 722 radially closer to an axis of rotation than the second ply 722.
Referring also to FIG. 4c, a corresponding embodiment of manufacturing a carcass of FIG. 5a comprises providing a third web 830 of a third ply material 832, the third web extending in the longitudinal direction SL, having a third width W3 in the transversal direction ST, and comprising third cords 834 extending in a direction forming a fourth angle α4 of at most 10 degrees with the transversal direction ST. The embodiment comprises winding also at least a layer of the third ply material 832 onto the carcass drum 300 such that
- the transversal direction ST is parallel to the axis of rotation AX of the carcass drum 300,
- the second ply material 822 radially surrounds the third ply material 832,
- in a location, the direction to which the third cords 834 of the third ply material 832 extend forms a fifth angle α5 with the direction to which the second cords 824 of the second ply material 822 extend, wherein the fifth angle α5 is greater than the fourth angle α4.
As indicated in FIG. 4c, in an embodiment, on both sides of the third web 830, the second ply material 822 extends in the direction of the axis of rotation AX outwardly from a boundary (836, 838) of the third ply material 832. Moreover, in an embodiment, the second ply material 822 is next to the third ply material 832 in the radial direction.
Referring to FIG. 5a, if a third ply 732 is used, preferably the width W3 of the web of sheet, from which the third ply is manufactured, is even smaller than the width W2 of the web of sheet, from which the second ply 722 is manufactured. This ensures that the cords of all layers are arranged in a mutually cross-wise manner also at the bead areas, and in particular at all points of the bead area. In an embodiment, the third width is at least 5 mm or at least 10 mm less than the second width W2, i.e. W2−W3≧5 mm or W2−W3≧10 mm.
Referring to FIGS. 4c and 5a, in an embodiment of the tyre 100, the carcass further comprises third ply material 832 in such a way, that in the crown area 191, the second ply material 822 radially surrounds the third ply material 832 (see FIG. 5a). Moreover, the third ply material 832 comprises third cords 834 extending within the third ply material 832 in a third direction that depends on a location within the tyre 100. And in the crow area 191, the third direction forms a fourth angle α4 with the direction of the axis of rotation AX and a fifth angle α5 with the direction to which the second cords 824 of the second ply material 822 extend at that location. The fourth angle α4 is at most 10 degrees and the fifth angle α5 is greater than the fourth angle α4. The fourth angle α4 may be e.g. from 0.5 to 5 degrees, such as from 1 to 3 degrees.
The third ply material 832 is arranged, in the radial direction, next to the second ply material 822. Thus, no such material that comprises cords, such as other ply material, is arranged in between the third ply material 832 and the second ply material 822.
The third ply material 832 comprises rubber as a matrix material and the third cords 834 integrated with the matrix. The third cords may comprise at least one of cotton, rayon, polyamide (Nylon), polyester, polyethylene terephthalate, and Poly-paraphenylene terephthalamide (Kevlar). The third cords 834 may be made of from the same material as the second cords 824. The rubber of the third ply material 832 may be the same as the rubber of the second ply material 822.
With reference to FIG. 5b, should a wider web or sheet be used for the third ply, a region of the type “RB” (as indicated in the figure with the reference “RB”) might be formed. In such a region, the cords of two of the neighbouring layers would extend substantially in parallel. In particular, the cords of the outer layer 736 of the material of the third ply 530 could be substantially parallel with the cords of outer layer 716 of the material of the first ply 712.
Referring to FIG. 6, a tyre 100 and/or an annular carcass may comprise further plies, in particular, a fourth ply 742 of fourth ply material 842. The fourth ply 742 may be the one neighbouring the third ply 732 radially closer to an axis of rotation than the third ply 732. Referring to FIG. 6, if a fourth ply 742 is used, preferably the width of the web of sheet, from which the fourth ply is manufactured, is smaller than the width W3 of the web or sheet, from which the third ply 732 is manufactured. Moreover, preferably the width W3 of the web or sheet, from which the third ply 732 is manufactured, is even smaller than the width W2 of the web of sheet, from which the second ply 722 is manufactured. This ensures that the cords of all layers are arranged in a mutually cross-wise manner at all locations of the tyre.
Patent Application
20170326920
