JPH0324363B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a tire bead reinforcing hoop.

The tire bead is reinforced by a hoop of substantially non-stretchable material, which must meet a number of requirements, including:

First, the hoop must have sufficient tensile strength to withstand the compressive action on the elastomer between the bead reinforcement and the bead seat of the wheel rim. This compression provides the sealing effect in the case of tubeless tires and also provides the essential bond between the tire and the wheel rim for transmitting driving, braking and steering forces in all tires. are doing. The hoop must also withstand the tensile forces exerted on it by the carcass reinforcement of the tire due to the air pressure within the tire. The third tensile strength requirement for the hoop is for tire components,
In particular, it is necessary to withstand centrifugal forces resulting from the mass of the tread and breaker assembly, which, in high-speed vehicles, is comparable to the force due to air pressure in tires.

Second, the bead reinforcement may allow one or more carcass plies to be wrapped around the bead reinforcement, such that the anchoring action of the plies at the bead is impaired or the plies are It must have a cross-sectional profile that allows the ply to be anchored to the bead without risk of fraying. In the prior art, this has been accomplished by shaping the bead components with elastomeric strips attached to the bead hoop so that the ply follows a smooth curve around the bead hoop, or by using triangular apex strips. The shape of the bead components was determined by Such an apex band is positioned with one short side adjacent the reinforcement hoop and long sides projecting radially outwardly into the tire sidewall. After the layer or layers of plies are wrapped around the bead hoop, the plies are folded back parallel to each other to form the final anchoring joint. It will be done. Stress concentrations in one or more carcass plies are thus avoided, which could cause failure of the structure.

Yet another requirement for bead reinforcements is that they must withstand the rigors of tire installation and removal, which often places high loads on small areas of the bead. A typical example is the use of a tire lever to remove a tire from a wheel rim.

It should be appreciated from the foregoing that circumferential reinforcements for tire beads serve a number of important functions.

In the prior art, tire beads are reinforced with bundles of steel wire. In some designs, steel wire is used in the form of a spiral winding, e.g., four turns of four juxtaposed steel wires to provide a 4x4 bead hoop structure. Various types of bead reinforcing structures are used, such as structures in which the number of wires arranged in parallel is other than four, or structures in which the number of turns is other than four.

The strip of four, five, or any other number of wires juxtaposed to each other is rubberized such that the assembled bead hoop is confined within the rubber and the platingable wires are held within the hoop upon curing. It is designed to be joined together. In some cases, especially in the case of tires for heavy vehicles, cross-sectional shapes other than rectangular may be used depending on the compressive force required of the bead and the bead properties which depend on the shape and angle of the bead seat on the wheel rim. wire array.

In other bead structures according to the prior art, the steel wires are arranged in the form of a cable.

These prior art structures have a significant problem in that the selection of possible bead shapes is limited and it is difficult to maintain the bead shape during subsequent steps of wire manufacturing. There is.

The purpose of the present invention is to solve the above-mentioned problems.

The tire bead reinforcing hoop according to the invention has a band of metal sheet formed in the shape of a tube,
The bands overlap such that one edge is on the outside of the tube and the other edge is on the inside of the tube, and the tube extends around the entire circumference of the bead to form a hoop. ing.

Preferably, the band is formed by winding the band multiple times so that the tube wall has at least two metal sheets.

Further, one outer edge of the band is attached to a metal sheet by, for example, welding or the like.

The preferred cross-section for the tubular hoop is circular, although other cross-sectional shapes may be used, including rectangular or circular with a flat portion on the radially inner portion of the hoop.

The tubular hoop may have a cross-sectional shape that varies along its length, allowing the properties of the tire bead reinforcement to vary over a wide range. In particular, the extensibility and/or flexibility of the tubular hoop can be achieved by varying the cross-section, for example by a series of annular grooves or an annular groove formed at intervals along the outer wall of the tubular hoop. It can vary depending on the restricted area or areas. The groove may extend completely around the cross-section of the tubular hoop, or it may extend only partially around the tubular hoop. The cross-sectional variation may consist of one or more helical grooves. If two or more helical grooves are used, the grooves may be separated from each other or connected to each other at specific points.

The spacing between adjacent sections of varying cross-section can be varied according to the required properties of the bead reinforcement. Adjacent portions of the tubular hoop may be joined together, for example by welding, to provide additional strength as required for a particular bead.

Preferably the metal sheet is steel and may be plated with a non-ferrous metal such as brass to promote adhesion to elastomeric materials used in tire construction. However, other metals such as brass may also be used. Plating may be performed before or after forming the tubular hoop.

The bead hoop may be coated with an elastomeric tire compound upon completion of forming the band, which is preferably made of metal sheet, but the rolled metal sheet layers are separated from each other by the elastomer and the vulcanized tire compound is used. It is also possible to protect the metal sheets with an elastomer material before forming so that they are joined together by the elastomer in the bead. When applying elastomer to a tubular hoop after it has been formed, instead of using a thin coating, the elastomer is formed to form the apex band, bead toe, or other elastomer component that is needed adjacent to the bead reinforcement. may be provided. Such an assembly may be partially or fully cured before being incorporated into a tire, or may be used uncured.

The preferred thickness of the metal sheet for an automobile tire bead made from a metal sheet is in the range 0.3 to 0.7 mm when two layers of metal sheet are used for the wall of the tubular hoop.

The band of sheet metal may be a continuous band cut from a seamless tube or rolled from a seamless tube, or it may be made of sheet material by joining the bands end to end. It may be formed from a band-like body. or,
The metal sheet material may be in the form of a ring or washer stamped from a flat sheet of steel. Any conventional joint may be used, but
Suitable joints may be straight-cut end-to-end butt welds, or angle-cut end-to-end joints such as butt welds. It's okay to be hot.

This type of tire bead reinforcement can be used in all tires, including automobile and truck tires, that utilize bead hoops.

Preferably the winding operation is carried out in one or more winding stages, each winding stage being able to be carried out hot or cold, although cold winding is preferred.

The winding operation is carried out by inserting a circular band into a chuck, engaging one edge of the band with the chuck, and then gradually forming the other edge into a tubular shape by successive spatula drawing operations. be done. The tube is then completed by removing the band from the chuck and completing the forming operation by rotating the band between a pair of forming enveloping rolls, placing the outer edges of the band in overlapping relationship to the tube.

A circular endless band may be made by cutting the required width from the end of a seamless tube of the correct diameter, or alternatively, cutting a ring of one width from a seamless tube of smaller diameter and cutting that ring into the final It can also be made by cold rolling to the required width and diameter. Alternatively, it may be made by cutting a length of steel strip, rolling it into a ring, and joining the rings end to end. For example, the joining is performed by butt joining and welding the ends of the strips.

According to the present invention, there is further provided a vehicle tire having a bead reinforced with the hoops described above.

Embodiments of the invention will now be described with reference to the accompanying schematic drawings.

The tubular tire bead reinforcing hoop shown in FIG. 7 has, in cross section, a roll consisting of two turns 1 and 2 of high-strength steel sheet. . One edge 3 of the sheet is located inside the winding and the other edge 4 is located outside the winding and overlaps the tube formed by the steel winding. The winding body is continuous around the entire circumference of the hoop.
The same circular cross-section is maintained around this hoop to provide a complete tubular bead reinforcing hoop, which in the case of automobile tires is typically made of 0.5 mm thick brass plating. Molded from high tensile strength steel sheet with a diameter of 350 mm
We offer finished bead hoops with a cross-sectional diameter of 10 mm.

Preferably, the wound tube is coated with uncured rubber to provide a bead assembly suitable for use in conventional tire manufacturing processes.

The beads are made of steel that is efficiently formed and has a constant cross-sectional shape that is not disturbed during tire manufacturing or vulcanization.

Additionally, bead hoops with other cross-sectional shapes can be made, one example of which is shown in FIG. A flat bead seat 5 is provided at the inner part. The bead also has a preformed apex band 6 of rubber, which is attached to the tube in the correct position before forming the bead into a tire.

Many other cross-sectional shapes can be made using the basic wound structure, and several bead sizes and bead strengths can be obtained by selecting the number of turns in the wound body. Metal sheets of the same thickness can be used.

Additionally, as shown in FIG. 9, short modified cross-sectional areas 21 and 22 may be formed in the tube to provide modified characteristics to the bead hoop.

The first deformation zone 21 has one annular groove formed on the outer surface of the tubular bead. This first deformation section 21 provides a shorter section in the longitudinal direction of the tube that is more extensible. Greater elongation potential can be obtained without reducing the breaking strength or changing the proportionality limits. The annular groove also provides greater flexibility of the tubular hoop. The number of spaced apart deformation areas around the circular bead hoop, the size of the grooves and the number of grooves can be varied to provide the required properties of the bead hoop.

The second deformation area 22 provides an alternative configuration in which four series of grooves 23 are used. The effect of this second deformation zone is the same as that of the first deformation zone, but differs in the degree of flexibility.
Obviously, different numbers of grooves may be used and the number of groove groups per bead hoop may be varied depending on the required properties.

Two further cross-sectional variants are shown in FIG. The one on the left in FIG. 10 uses a pair of adjacent semi-circular annular grooves 24 and 25 which cooperate with each other to provide a deformation strength area 26. The one on the right in Figure 10 has one short longitudinal groove 2.
7 is used, and this groove 27 makes it possible to change the bending strength, that is, the flexibility, without changing the longitudinal properties.

Another pair of cross-sectional variations are shown in FIG. In FIG. 11, the one on the left uses one spiral groove 28, and the one on the right uses a pair of spiral grooves 29 and 30 wound in opposite directions. The grooves may be continuous around the entire bead hoop, or they may be a series of spaced grooves having a length.

The overlapping edges 4 are preferably left unattached as shown, although in some cases the edges 4 may be attached to the tube, such as by welding.

1-6 illustrate the steps in making the bead reinforcing hoop of FIG. 7. FIG.

First of all, the flat steel strip is a circular band 7
and the ends are joined by diagonal butt welds 8 such as serrations or axial butt welds 8A to provide a continuous ring of constant cross section. The band 7 is then mounted in a chuck 9 provided in a spatula draw lathe which holds one edge 4 of the band 7 as shown in FIG.
Next, a channel or groove 1 is formed with a curved part.
A pair of cooperating spatula drawing dies 11 and 12 are moved in the direction of arrow 14 toward the rotating chuck 9 and band 7 to form the shape shown in FIG. . When this first spatula drawing stage is completed, the spatula drawing die 11
and 12 are separated from each other and disengaged from band 7. At this time, band 7 is curved edge area 1
5.

A second using a second pair of dies 16 and 17.
The spatula drawing operation is shown in FIG. These dies 16 and 17 cooperate with each other to define a generally circular cavity 18 which, as the dies 16 and 17 are moved towards the rotating chuck, is connected to a fifth die. The rolled shape 19 shown in the figure is formed.

Band 7 is then removed from chuck 9 and
As shown in FIG.
It is rotated within a nip between a pair of rolls 20A and 20B that rotate around 0B'. The rolls 20A and 20B are wound around the edge 4 so that it is in the final position shown in FIG. 7 to complete the winding of the tubular bead hoop.

Other winding or spatula drawing processes may be used to create various types of beads of different materials and different thicknesses.

The beads may be wound in shapes other than circular, for example rectangular, or may have flat areas as shown in FIG.

Obviously, for example FIGS. 9, 10 and 11
The modified cross-sections shown can be formed before or after forming the tube to obtain the required bead hoop characteristics.

Rubber coating operations on the hoop may be accomplished by applying sheet material by subsequent dipping, or by wrapping a strip of material, or by rotating the hoop in a T-head extruder. Additionally, if a T-head extruder is used, additional rubber parts such as special toes or apexes for the beads may be added to the head hoop.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an endless band of sheet steel material used for manufacturing a bead reinforcing hoop according to an embodiment of the present invention, and FIGS.
The figure is a partial cross-sectional view of a molding machine used for molding bead hoops, and Figures 3, 5, and 7 are those manufactured by the molding machines shown in Figures 2, 4, and 6, respectively. Figure 7 shows a finished bead cross-section, Figure 8 shows another bead cross-section, and Figure 9 shows two deformed cross-sectional areas. FIG. 10 is a side view showing a part of the cylindrical tire bead, and FIG.
It is a diagram showing a deformed cross-sectional area different from the diagram,
FIG. 11 is a diagram showing a modified cross-sectional shape different from that of FIG. 9. 1, 2... Winding portion, 3, 4... Edge, 5... Bead seating portion, 6... Apex band, 7...
Circular band, 8, 8A... welding part, 9... chuck, 10... edge of band, 11, 12... spatula drawing die, 13... channel, 14...
...arrow, 15 ... edge area, 16, 17 ... die, 18 ... circular void, 19 ... rolled shape,
21, 22...Deformed cross-sectional area, 23, 24, 25
...Groove, 26...Deformation strength area, 27...Groove, 2
8, 29, 30... spiral groove.

Claims (1)

[Scope of Claims] 1. A hoop for reinforcing a tire bead, comprising a band of a metal sheet formed in the shape of a tube, one edge of the band being located outside the tube and the other edge being located outside the tube. A hoop for reinforcing a tire bead, wherein the tubes overlap each other so as to be located inside the tube, and the tube extends over the entire circumference of the bead to form a hoop. 2. In the tire bead reinforcing hoop according to claim 1, the band is formed by winding the band multiple times so that the wall of the tube has at least two layers of metal sheets. Hoop for tire bead reinforcement. 3. The tire bead reinforcing hoop according to claim 1 or 2, wherein one of the outer edges of the tire bead is attached to the metal sheet by welding. Reinforcement hoop. 4. The tire bead reinforcing hoop according to any one of claims 1, 2, and 3, wherein the tube has a circular cross section. 5. The tire bead reinforcing hoop according to any one of claims 1, 2, and 3, wherein the tube has a rectangular cross section. 6. In the tire bead reinforcing hoop according to any one of claims 1, 2, or 3, the cross section of the tube includes a flat portion in a radially inner portion of the hoop. A circular hoop for tire bead reinforcement. 7. In the tire bead reinforcing hoop according to any one of claims 1 to 6, the cross-section of the tube is varied along the longitudinal direction of the tube, so that it can be expanded. and/or tire bead reinforcing hoops with varying flexibility. 8. The tire bead reinforcing hoop according to any one of claims 1 to 6, wherein the tire bead has a series of annular grooves formed at intervals around the outer surface of the tube. Reinforcement hoop. 9. A tire bead reinforcing hoop according to claim 8, wherein each of the annular grooves extends over only a portion of the circumference of the tube. 10. The tire bead reinforcing hoop according to any one of claims 1 to 6, which has at least one spiral groove formed on the outer surface of the tube. 11. The tire bead reinforcing hoop according to any one of claims 1 to 10, wherein the metal is steel. 12. In the tire bead reinforcing hoop according to any one of claims 1 to 11, the metal sheet is pre-coated with an elastomer material before forming, and the elastomer is Tire bead reinforcing hoops are located between the two layers and bond them together. 13. The tire bead reinforcing hoop according to any one of claims 1 to 12, wherein the metal band is endless.