Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-06-22
2001-05-15
Knable, Geoffrey L. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S133000
Reexamination Certificate
active
06231708
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a pneumatic vehicle tire by producing a green carcass on a cylindrical carcass building drum with at least the following steps:
a) applying the inner liner onto the cylindrical carcass building drum,
b) applying at least one carcass ply, containing textile reinforcement elements or comprised thereof, whereby the ends of the applied carcass ply have an overlap zone,
c) positioning the bead cores,
d) subsequently completing and vulcanizing the green tire in a conventional manner.
For the manufacture of a vehicle tire the individual components of the tire are sequentially wound onto the building drum. The individual plys are cut to strips that have a length reaching once around the drum circumference. When winding the individual strips, it is, in general, desired that the ends of each strip overlap in order to ensure that after producing and vulcanizing the green tire there are indeed closed plies in the circumferential direction which ensure the proper functioning of the finished tire.
Therefore, when applying the carcass ply, which especially in passenger car tires is comprised mostly of textile reinforcement elements embedded in rubber material, the trailing and leading ends of the applied carcass ply are overlapped. In the overlap zone (approximately 2-6 mm wide) a doubling of the material thickness is thus provided. Accordingly, the textile reinforcement elements are also present with double density. These reinforcement elements extend, for example, in the manufacture of radial tires, transverse to the circumferential direction of the building drum, and may be comprised of, for example, rayon, polyester or other organic reinforcement elements. Polyester has the advantage that it is less expensive. However, reinforcement elements consisting of polyester have the disadvantage that they have a higher stretching ability. At the overlap zone of the carcass ply in which, as mentioned above, a higher reinforcement element density is present, the same force load results in reduced stretching of the carcass ply within the overlap zone, in comparison to other carcass ply zones, when the tire is inflated because of the changed modulus of elasticity withing the overlap zone. In the inflated state of the tire, the seam is thus visible as a constriction within the sidewall. The quality and stability of the tire is not affected by this, however, this is a visual defect which especially by laymen is interpreted as a rupture within the carcass so that the tire is returned to the tire or the vehicle manufacture as a defective tire.
It is therefore an object of the present invention to prevent the constriction of the tire within the sidewall area.
SUMMARY OF THE INVENTION
A method for manufacturing a pneumatic vehicle tire according to the present invention is primarily characterized by the following steps:
a) providing a cylindrical building drum with a bar or a depression having a longitudinal extension in a direction parallel to the orientation of reinforcement elements of a carcass ply to be applied to the building drum;
b) positioning a lining on the cylindrical building drum;
c) placing at least one carcass ply, comprising reinforcement elements and having a leading end and a trailing end, onto the lining such that the leading end and the trailing end overlap in an overlap zone at the bar or the depression, thereby forming an overlength of the reinforcement elements in the overlap zone for preventing a constriction of the overlap zone within the vulcanized, inflated tire;
d) completing the green tire on the building drum;
e) vulcanizing the green tire.
Advantageously, the step a) includes selecting the bar or the depression to have a length of 50-300 mm, a width of 8-15 mm, and a height of 3-5 mm.
Advantageously, in the step c) the overlength is produced at least within a radially outer carcass ply.
The step c) includes selecting the carcass ply to have reinforcement elements consisting of polyester.
Advantageously, the present invention also includes a method for manufacturing a pneumatic vehicle tire characterized by the following steps:
a) positioning a lining on the cylindrical building drum;
b) placing at least one carcass ply, comprising reinforcement elements and having a leading end and a trailing end, onto the lining such that the leading end and the trailing end overlap in an overlap zone;
c) folding the carcass ply in the overlap zone into a least one fold to form an overlength of the reinforcement elements in the overlap zone for preventing a constriction in the overlap zone within the vulcanized, inflated tire;
d) completing the green tire on the building drum;
e) vulcanizing the green tire.
Advantageously, in the step c) the overlength of the reinforcement elements resulting from the at least one fold is 3-10 mm.
In the step c) the overlength is produced at least within the radially outer carcass ply.
Expediently, the step b) includes selecting a carcass ply having reinforcement elements consisting of polyester.
The present invention also relates to a carcass building drum comprising a cylindrical drum surface and a bar connected to the drum surface and extending in the axial direction of the building drum. The bar has a length of 50-300 mm, a width of 8-15 mm, and a height of 3-5 mm.
Advantageously, the invention also relates to a carcass building drum comprising a cylindrical drum surface and a depression provided in the drum surface and extending in the axial direction of the building drum. The depression has a length of 50-300 mm, a width of 8-15 mm, and a height of 3-5 mm.
Advantageously, the present invention also relates to pneumatic vehicle tires comprising a lining, beads, a carcass having textile reinforcement elements placed onto the lining and connected to the beads, whereby the tire is manufactured according to the methods of the present invention.
According to the present invention, the cylindrical carcass building drum in the overlap area of the carcass ply has a discontinuity in the form of a bar or a depression (groove). The discontinuity extends substantially parallel to the extension of the textile reinforcement elements of the carcass ply. When the carcass ply is applied to such a building drum, an overlength of the textile reinforcement elements is produced within the overlap zone and this overlength compensates the constriction that otherwise would be observed upon inflation of the finished tire within the overlap zone.
With this simple constructive measure at the cylindrical carcass building drum the problem of constriction formation within the sidewall area is solved in an uncomplicated manner. The reinforcement elements within the overlap zone have a greater length between the bead cores of the green tire than within the remaining area of the carcass ply.
It has been proven to be advantageous when the cylindrical carcass building drum has a protrusion (for example, a bar) or a depression (for example, a groove) which has a length of 50-300 mm, a width of 8-15 mm, and a height, respectively, depth of 3-5 mm. When producing a radial tire, the carcass ply is applied such that the reinforcement elements of the carcass ply extend substantially in the axial direction of the carcass building drum. The lengthwise extension of the protrusion or depression then extends also substantially in the axial direction of the carcass building drum when producing such a tire. The individual size of the depression or protrusion depends on the respective tire size to be manufactured. However, the size is selected such that an overlength of the reinforcement elements within the overlap zone is produced between the bead cores or the bead apexes whereby the remaining reinforcement elements of this carcass ply, outside of the overlap area, are not elongated. The height or depth of the protrusion or depression has a direct effect on the overlength of the textile reinforcement elements. Accordingly, an overlength of the textile material is produced which correspondence to maximally twice t
Glinz Michael
Sergel Horst
Continental Aktiengesellschaft
Knable Geoffrey L.
Robert W. Becker & Associates
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