Method of and apparatus for producing single wire beads for...

Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor

Reexamination Certificate

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Details

C156S259000, C156S422000

Reexamination Certificate

active

06228198

ABSTRACT:

This invention relates to a method of producing at the same time two or more single wire bead wire cores wound into a particular shape. In particular the method relates to the production of bead wire cores each having a plurality of convolutions, e.g. 70 or 80 convolutions, forming a bead wire core having a hexagonal section, for example as is used for a truck tyre. The invention also relates to an apparatus for producing such tyre bead cores.
Many tape or weftless bead lines are used to produce at the same time one, two or even three tyre bead cores for automobiles. To do so, a wire/compound tape is prepared at an extruder head of a width equivalent to the multiple width of the number of simultaneous bead wire cores to be produced. This single, but wide, tape is passed through a single pull-off drum and festooner system into a winding machine.
The tape is drawn into the winding machine and, if more than one bead wire core is to be produced, the tape is split into the appropriate number of individual tapes before being gripped in a former of the winding machine where it is wrapped as one, two or three beads simultaneously. Typically it will be wrapped in 4, 5 or 6 convolutions, each convolution being vertically stacked on top of the previous convolution, before being removed from the former.
The passing of a single tape through the back-up equipment before being split, together with the small number of vertically stacked convolutions has proven to be a satisfactory system for winding these kinds of weftless bead wire cores.
However, for single wire, programmed, hexagonal shaped bead wire cores for use in truck tyres, the same simple principles do not apply. These bead wire cores typically comprise about 70 or 80 convolutions of a single wire instead of the 4 to 6 convolutions of a tape in a weftless bead wire core. In addition each convolution of the single wire has to be positioned very accurately into a pre-determined pattern, e.g. in the shape of a hexagonal or an off-set hexagonal cross-section, usually with a 15 degree base angle. This is very difficult to achieve in comparison to the simple vertical stacking of weftless bead wire tape.
Additionally, there are a large number of variations in the construction of truck bead wire cores, depending on the size, type and duty of the tyre.
When winding more than one bead wire core side by side and simultaneously, it is inevitable that, due to slight differences in cast and helix and diameter tolerances in the wire, together with unpredictable variations in rubber coating thickness and wire positioning in the bead construction, that the actual length of wire used may vary slightly between each of the bead wire cores being wound simultaneously.
Over even a small number of bead winding cycles, an accumulation of these small variations would affect the quality of the bead wire cores produced and render the bead line inoperable unless the operating system could adequately deal with the problem.
It is for this reason that single wire bead lines designed for producing hexagonal bead wire cores for truck or high performance motor car tyres are conventionally fitted with a separate pull-off and festooner assembly for each wire run.
A normal known single wire bead line is fitted with one pull-off and one festooner assembly and is used to build one bead wire core at a time. More recently it has been known to have high output bead lines which produce up to 6 single wire bead wire cores at a time. However, in order to operate properly, these bead lines have had to include a separate motorised pull-off and festooner assembly for each bead wire core produced, each assembly being separately driven by a D.C. or servomotor drive and separately controlled, e.g. by a computer control system.
The known existing machines that produce only one bead wire core at a time are expensive to buy and in labour costs per bead. Those machines producing multiple beads are very sophisticated but are expensive and only really viable for the largest tyre companies.
An aim of the present invention is to enable at least two single wire bead wire cores, e.g. hexagonal section bead wire cores, to be built at the same time using only a single pull-off and a single festoon assembly.
A further aim of the present invention is to provide apparatus which has an increased output over existing widely used single wire bead lines but which can be built relatively cheaply.
According to one aspect of the present invention a method of producing at least two single wire tyre bead cores comprising drawing off at least two bead wires from separate coils of wires, passing the wires through processing means to coat the drawn-off wires with rubber material, passing the rubber-coated wires through first festooner apparatus, preferably a single festooner apparatus, and subsequently winding the rubber-coated wires on a former to create at least two single wire tyre bead cores on the former, is characterised in that before the wires are passed through said first festooner apparatus they are joined together in said wire processing means, in that the joined together rubber coated wires are split after passing through said first festooner apparatus and in that the wires, after being split, are passed through second festooner apparatus before being wound on said former.
The wires, after being split, are individually tensioned in the second festooner apparatus to control their winding onto the former to compensate for variations in their lengths. Thus the apparatus is able to restrict any bead wire length variations to within the confines of the winding machine. Any such length variations can be measured against the specification of the bead being wound and either incorporated into, or removed from, the tyre bead cores during the final winding stage. In this way dual bead wires can be produced without an accumulation of loose bead wire appearing in the process line or the need for separate draw off means and festooner apparatus being included to accommodate it.
Conventionally it is necessary, for each bead wire, to have separate festooner apparatus and wire pull-off apparatus (which may be combined with the festooner apparatus). However in the method according to the present invention, the joining together of the bead wires to form a temporary single “tape” of bead wire, allows only a single festooner apparatus and pull-off apparatus to be used, before the “tape” is split into individual bead wires prior to winding. Thus only a single one of the costly first festooner apparatus needs to be provided. By individually tensioning the split wires in the second festooner apparatus before they are wound onto the former, variations in the wire lengths forming the different beads can be compensated for.
Preferably the wires, when passing through said wire processing means, are initially coated with the rubber material before they are pressed together. In this way the still tacky rubber coated wires are temporarily joined together until they are subsequently split or separated after passage through the first festooner apparatus.
According to another aspect of the present invention apparatus for producing at least two single wire tyre bead cores, the apparatus comprising at least two let off stands each containing a wound reel of bead wire, draw off means, preferably a single draw off means, for drawing bead wire from said reels, wire processing means between said draw off means and said let off stands including coating means for coating the bead wires with rubber material, winding means for winding rubber-coated bead wire onto a former to produce at least two single wire tyre bead cores and first festooner apparatus, preferably a single first festooner apparatus, positioned between the draw off means and the winding means, is characterised in that said wire processing means further includes joining means for joining together the rubber coated bead wires, in that splitter means are provided between the first festooner apparatus and the winding means to split the joined together bead wires into separate bea

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