Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-06-25
2001-03-20
Knable, Geoffrey L. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S111000, C156S130500, C156S133000
Reexamination Certificate
active
06203641
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the manufacture of tires. More particularly, it relates to techniques for the manufacture of tires on a support the shape of which is very close or even identical to the final manufactured shape of the tire.
U.S. Pat. No. 4,895,692 describes a tire mold having a rigid core which determines the inner shape of the tire; it also describes a process of assembling the tire with the use of such a mold. Such a mold can be considered “rigid”, since this mold imposes upon the tire a molding space of a given volume. This volume is bounded on the outside by the shells of the mold and by the group of sectors molding the tread, and on the inside by the rigid core. The use of this mold leads to a vulcanization stage with quasi-imposed volume. It is also known that most of the molds currently used at the present time are molds having only the two shells which assure the molding of the outside of the sidewalls and a ring of sectors which assure the molding of the outside of the tread. The use of these molds upon vulcanization leads, in order to assure the molding, to the spreading out within the raw tire of a flexible bladder, so that it can be considered that the vulcanization takes place in this case with imposed pressure and not with imposed volume.
SUMMARY OF THE INVENTION
The object of the present invention is to manufacture a tire on a support which is as close as possible to its final manufactured shape, in accordance with the technique described in U.S. Pat. No. 4,895,692, while carrying out a vulcanization step which is related rather to the process which has been referred to above as vulcanization with imposed pressure.
One object pursued by the invention is to create a process for the manufacture of a tire which avoids the tire blank undergoing, during its assembly, transfers consisting in displacing it from one drum to another or one support to another. All such transfers and manipulations of the blank are in fact the source of numerous inaccuracies in assembly and the source of defects in the uniformity of the tire produced.
For this purpose, the invention proposes a process for the manufacture of a tire which comprises an assembly phase forming a raw blank and a vulcanization phase, in which use is made of an inflatable flexible bladder capable of retaining by adherence the raw rubber constituting the inner skin of the tire during the assembly phase and capable of separating from the tire after vulcanization, which comprises the following stages:
said bladder is inflated to a given assembly pressure so as to form a reference support for the assembling, said support having a toroidal shape,
thereupon a raw blank is formed, starting by the depositing of the rubber constituting the inner skin of the tire by the winding of a ribbon, and then progressively depositing all the desired components, in the required order, onto said bladder,
the blank is then vulcanized,
and finally said bladder is deflated and withdrawn from the inside of the tire.
In order to effect the vulcanizing of the blank on the bladder itself, there can advantageously be closed around the blank a mold for the molding of the outer surface of the sidewalls and the tread, and the pressure of said bladder then adjusted to a molding pressure which is sufficient to assure the molding of the tire and, at the end of the vulcanization, the bladder is deflated in order to permit the separation of the skin and said bladder and to permit the discharge of the vulcanized tire.
This consists in manufacturing a tire completely on an inflatable bladder and then vulcanizing it on the same bladder, without any transfer of the blank with respect to the bladder. The bladder used is capable of maintaining the raw rubber constituting the inner skin of the tire upon the depositing during the assembly phase. It is understood by this that the rubber ribbon which is deposited on the bladder adheres to the latter sufficiently in order to remain in the place where it has been deposited. For the depositing of this ribbon, one can use different techniques, such as the depositing of a preshaped ribbon, or else the direct extrusion of an amount of rubber which is fully controlled as a function of the exact place where it is deposited on the bladder.
It is furthermore necessary that the bladder used can separate from the tire after use. In order to satisfy these conditions, it is made of a material which makes it possible to obtain a good raw adhesive (that is to say, a material which the raw rubber adheres to sufficiently for the requirements of the depositing), while assuring the separation of the vulcanized tire. For example, the bladder is made of rubber having a surface covering which satisfies the conditions indicated. Aside from the characteristic mentioned above, or in combination with it, one can also use an elastomer which has a certain level of incompatibility with the products used in the tire, and more particularly with the products of which the inner skin of the tire is made.
By “manufacture of a tire”, there is understood both complete and partial manufacture, that is to say, possibly, the manufacture of a unit comprising the crown reinforcements and the tread alone, or the manufacture of a tire without such a unit. Whatever the object manufactured, the reference support receives all the raw materials, which are in general deposited by winding on the support, as well as all the following materials for producing a complete assembly, contrary to other known arrangements in which the vulcanization bladder or else a receiving drum such as a second-stage drum receives a complex product formed of a semi-finished product obtained by the assembling of several elementary components.
By “support of toroidal shape”, there is understood a support the shape of the outer apparent surface of which is very far from a cylindrical shape, in order to approach a shape resembling the shape of the inner surface of the tire. This shape is therefore of a very different nature from the shape of the first-stage assembly drums known in the prior art which have a quasi-cylindrical surface, bordered on either side by a groove or a shoulder in order to define the position of the bead wires. This shape of revolution may have a radial section which is approximately a circular arc or else resembling a trapezoid.
In order to be able to manufacture a tire on a form which corresponds substantially to the final manufactured and vulcanized shape of the tire, a reinforced bladder is preferably employed. It is thus possible to obtain a flexible form which, once inflated to a pressure of the same order of magnitude as the inflation pressure of passenger car tires, behaves substantially as a rigid form. This permits the use of tire assembly tools which are known for the manufacture of a tire on a rigid core, such as those described in U.S. Pat. Nos. 4,801,344, and 4,804,436 or else 4,963,207, by way of illustration but not of limitation.
The invention also proposes a tire manufacturing module which comprises an inflatable flexible bladder which can be retracted when it is deflated, said module comprising means making it possible to anchor said bladder and making it possible to offer a hold for the displacement of the module and making it possible with said bladder to define an inflatable enclosure forming at least partially a support of toroidal shape in inflated state.
This module permits the assembling of a tire and its transfer then to a vulcanization station. The module preferably has two connecting sockets making it possible to circulate a fluid providing the heat necessary for the vulcanization. At the vulcanization station, the fluid used is, for instance, electricity, the module being for instance equipped with resistors capable of producing heat, or else a heat-exchange fluid which conducts heat to the inside of the module. As the case may be, said connecting sockets may be either electric inlets or connectors for gaseous or liquid fluid. Due to the sealing means between plates, it offers the possibility
Laurent Daniel
Mousty Herve
Baker & Botts L.L.P.
Knable Geoffrey L.
Sedepro
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