MANUFACTURE OF RUBBER MIXTURES FOR TIRES

TECHNICAL FIELD

The present invention relates generally to the production of rubber mixtures and vehicle tires made therefrom. More particularly, the present invention relates to the complete production of rubber mixtures by selective execution of production sequences.

BACKGROUND

In the manufacture of tires, it is required that the tire exhibit various performances (e.g., reduced rolling resistance, improved wear resistance, a comparable grip in wet and dry conditions, the estimated mileage, etc.). The tires are therefore made of various types of rubber compounds having properties critical for operation of the tire itself. For example, the patent FR2978370 discloses a process wherein the final temperature rises in a short time and at a very high level that greatly reduces the energy dissipation phenomena inside the material. The patent US4840491 discloses a method for controlling Mooney values by forming a sheet with a thickness not exceeding 3 mm. The publication US2009/0238027 discloses a method that uses a device for mixing rubber having a stable viscosity.

To ensure that a marketable tire has the expected performance, a rubber compound can be selected from a variety of rubber mixtures, each having various ingredients mixed in different amounts and derived from a variety of production sequences. Depending on the desired characteristics, such sequences may be carried out once, twice or even several times.

Although multiple types of rubber compounds are contemplated in the tire production process, there is a choice of, and an optimized implementation of, equipment that adapts itself to the choice of, the rubber mixture production sequence. Optimal productivity is therefore possible, while retaining the availability of diverse rubber properties.

SUMMARY

The present invention is directed to a method of realizing in a selective manner one or more sequences for producing a rubber blend composition according to a selected rubber mixing recipe. During a step I, using a series of rubber mixture production installations that define monopassage and multipassage sequences of rubber mixture production with the aid of a transport means that directs sequentially a rubber mixture to at least one rubber mixture production installation according to a selected rubber mixing recipe for the production of a rubber mixture having expected properties, each rubber production installation permitting the execution of at least one rubber mixture production process, a rubber mixture is realized that includes one or more elastomer(s) and ingredients, in selecting the operating parameters of the series of rubber production installations so that:

a -the residence time of the rubber mixture in a first internal mixer that performs an initial mixing process is between 120 and 180 seconds;

b -the residence time of the rubber mixture in an external mixer that passes the rubber mixture between two rollers to convert the rubber

mixture into a continuous sheet is between 120 and 180 seconds;

c - the residence time of the rubber mixture in a second internal mixer that performs a complementary mixing process is between 120 and

180 seconds; and

d - the specific energy supplied to the rubber composition at the outlet of the second internal mixer is lowered by about 20% with respect to

the specific energy supplied to a composition realized by a control process

that effects a monopassage sequence.

During a step II, at the outlet of the second internal mixer, temperature target values are obtained for the rubber mixture.

In certain embodiments, the series of rubber mixture production installations includes at least one mixing and cooling installation that performs a mixing and cooling process. The mixing and cooling installation has at least one external mixer having a pair of cylinders for transforming the rubber mixture into a continuous sheet and at least one spray system having one or more spray rails positioned at each of an upper spray station and a lower spray station. Each spray rail is in communication with a source for supplying water and air to one or more nozzles at a predetermined water flow rate and a predetermined air pressure. At least one aspiration system is provided that includes one or more aspiration hoods positioned downstream of each spray rail. Each aspiration hood is in communication with a source for supplying air at a predetermined air flow rate. During the mixing and cooling process, the mixing and cooling installation sprays the continuous sheet and evacuates the air containing the evaporated water in order to produce the rubber mixture at target values of temperature and water content before a complementary mixing process.

For certain embodiments of the invention, a target value of the temperature of the rubber mixture is about 70° C, and a target value of the water content of the rubber mixture does not exceed about 0.20% by weight of the rubber mixture.

For certain embodiments of the invention, the series of rubber mixture production installations includes at least one initial mixing installation that performs an initial mixing process; at least one complementary mixing installation that performs the complementary mixing process; and at least one end-of-line installation that performs an end-of-line process. For certain embodiments, the end-of-line process is selected from one or more of profiling, sampling, processing, cooling, palletizing and stocking the rubber mixture.

For certain embodiments of the invention, the transport means includes a transport installation configured for selective transfer of a rubber mixture to a preselected rubber mixture production installation. The transport installation includes an optional evacuation station including a spray rail and an aspiration hood; a retractable conveyance that allows selective transfer to the complementary mixing installation or to the end-of-line installation; and a conveyance that performs the selective transfer to the end-of-line installation.

In some embodiments, the retractable conveyance is positioned for performing a complementary mixing process from which the rubber mixture will be transferred to the end- of-line installation. In some embodiments, the retractable conveyance is positioned for transfer to the end-of-line installation without performing the complementary mixing process.

In some embodiments, during step I, one or more ingredients are incorporated that are selected from processing agents, protecting agents, reinforcing fillers, carbon black, and silica.

In some embodiments, during step I, the drop temperature from the first internal mixer does not exceed 180° C, and the drop temperature from the second internal mixer does not exceed 120° C.

In some embodiments, the method further includes the step of selecting the rubber mixture from a variety of rubber mixture recipes derived from one or more rubber production sequences.

Other aspects of the presently disclosed invention will become readily apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature and various advantages of the presently disclosed invention will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

FIG. 1 shows a schematic view of an exemplary system for producing rubber mixtures according to exemplary rubber production processes of the present invention.

FIG. 2 shows a schematic view of an exemplary cooling installation and an exemplary evacuation station used with the system of FIG. 1.

FIG. 3 shows the system of FIG. 1 during an exemplary monopassage rubber production sequence.

FIGS. 4 and 5 show the system of FIG. 1 during respective successive and final passages of an exemplary multipassage rubber production sequence.

DETAILED DESCRIPTION

Now referring further to the figures, in which like numbers identify like elements, FIG. 1 shows an exemplary system 10 for producing one or more rubber products to be incorporated into one or more vehicle tires. It is contemplated that system 10 enables production of rubber mixtures having variable and customizable properties as determined by the performance properties of the resulting tire. As used herein, the term "tires" includes but is not limited to tires used with lightweight vehicles, passenger vehicles, utility vehicles (including heavy trucks), leisure vehicles (including but not limited to bicycles, motorcycles, ATVs, etc.), agricultural vehicles, military vehicles, industrial vehicles, mining vehicles and engineering machines. It is also contemplated that the products produced by the presently disclosed invention include full and partial tire treads such as those used in known retreading processes.

System 10 includes a series of rubber mixture production installations that together delineate one or more sequences of rubber mixture production. Each rubber production installation enables performance of at least one rubber mixture production process. A rubber mixture is obtained and sequentially directed to one or more of the rubber production installations according to a variety of rubber mixture recipes. System 10 allows sequential execution of rubber production processes until the resulting rubber exhibits the desired performance properties, which properties are variable and adaptable according to the rubber mixture recipe.

The rubber mixture that is selected for production in a given mixing cycle may be selectively obtained from a production sequence that is performed only once (hereinafter a "monopassage" sequence) or a production sequence that is carried out twice or more (hereinafter a "multipassage" sequence). A multipassage sequence may include one or more successive passes through at least part of the system before a final pass. The rubber mixture can thus be manufactured from a predefined recipe selected from among a plurality of rubber mixture recipes amenable to production by either by a monopassage sequence or by a multipassage sequence.

Control of the rubber mixture's properties is carried out not only by the ingredients selected for a given rubber mixture, but also by the order of their introduction as well as any intermediate steps. Since the configuration of system 10 remains static irrespective of whether it performs a multipassage or a monopassage sequence, an extensive selection of rubber mixture recipes becomes available that are suitable for the manufacture of tires. In this sense, the system allows the production of rubber mixtures from recipes with monopassage sequences or recipes with multipassage sequences without the need for separate equipment.

Still referring to FIG. 1, among the rubber production installations provided with system 10 is an initial mixing installation 20 that performs an initial mixing process. Mixing installation 20 includes at least one internal mixer 22 having a chamber 24 of a predetermined fill volume. Internal mixer 22 includes one or more mixing blades (not shown) that ensure penetration of rubber ingredients into an elastomer matrix. Internal mixer 22 may be selected from a variety of commercially available mixers.

In an initial step A of both monopassage and multipassage sequences (see FIGS. 1 and 3 to 5), performed at initial mixing installation 20, internal mixer 22 receives elastomeric material 27 (e.g., natural rubber, synthetic elastomer and combinations and equivalents thereof) and one or more rubber ingredients such as one or more of implementation agents 29, protection agents 31 and reinforcing fillers 33. The rubber ingredients may include one or more of carbon black or silica in varying quantities depending upon the desired performance properties of the tire. It is understood that other rubber ingredients may be introduced into internal mixer 22 with the exception of vulcanization (e.g., cross-linking) ingredients, which are introduced later in the sequence.

In a subsequent step B of both monopassage and multipassage sequences (see FIGS. 1 and 3 to 5), also performed at initial mixing installation 20, internal mixer 22 mixes the elastomeric material and the rubber ingredients to obtain a rubber mixture therefrom. The initial mixing process employs general mixing techniques as is known in the art. In some processes, mixing takes place at a temperature of not more than 180°C.

Still referring to FIG. 1 and further to FIG. 2, a rubber mixture 108 obtained from initial mixing installation 20 is conveyed to a mixing and cooling installation 100 for performance of a cooling process thereat. Mixing and cooling installation 100 is a rubber production installation that includes at least one external mixer having a pair of cylinders 110. Each cylinder 110 has a rotational axis and the cylinders are arranged in a mutually opposed manner such that the rotational axes are parallel to one another. Cylinders 110 may exhibit identical diameters and lengths to ensure uniform and repeatable performance thereof during successive mixing cycles. One or both of cylinders 110 may have fluid or commensurate cooling means integrated therein as is known in the art. Subsequent to the initial mixing process performed at initial mixing installation 20, system 10 conveys rubber mixture 108 between cylinders 110 to form a continuous sheet 112 having a selected thickness and width.

Mixing and cooling installation 100 also includes at least one upper spray station 102 and a lower spray station 104 that are both incorporated into a spray system that sprays water and an aspiration system. The spray system includes one or more respective spray rails 124, 126 positioned at each of the upper and lower spray stations. Each spray rail is in

communication with a water supply source and an air supply source that supply water and air to one or more nozzles at a predefined water flow rate. The aspiration system includes one or more respective aspiration hoods 134, 136 positioned downstream of each rail. Each aspiration hood is in communication with an air supply source for the aspiration of air. The addition of water by the rails 124, 126 supplies the ambient air with moisture. The air containing evaporated water is aspirated to prevent the introduction of water into the rubber mixture. Each combination of rail and aspiration hood serves as a checkpoint that optimizes the cooling of rubber mixtures 108 over the entire production line.

In a step C, both for monopassage and multipassage sequences (see FIGS. 1 and 3 to 5) performed at mixing and cooling installation 100, cylinders 110 transform rubber mixture 108 into a continuous sheet 112 which then circulates according to a predefined path. The predefined path includes one or more continuous conveying means (for example one or more conveyor belts or transport equivalents). For the example of mixing and cooling installation 100 illustrated in FIG. 2, the predefined path is formed at least partly by a continuous belt 114 positioned at the upper spray station 102 and another continuous belt 116 positioned at the lower spray station 104. Belts 114, 116 are driven at least by an upper roller 118 and a lower roller 120 of larger relative diameter. One or more auxiliary rollers 122 can complement the belts 114, 116 as is known in the art. Although the belts 114, 116 are described as separate transport means, one continuous belt can replace them. During step C, rubber mixture 108 is transported by belt 114 in a direction for treatment at upper spray station 102. Belt 114 transports rubber mixture 108 between cylinders 110 to form continuous sheet 112. Belt 116 transports the sheet in a direction for treatment at lower spray station 104. On the basis of the unique properties of rubber mixture 108, each spray rail 124, 126 sprays water at a predetermined flow rate and each respective aspiration hood 134, 136 aspirates the air. The addition of water by rails 124, 126 loads the ambient air with moisture and promotes the extraction of heat during mixing. The purpose of the aspiration is to limit condensation and thereby prevent the introduction of excess water into rubber mixture 108. Each ramp and aspiration hood combination therefore serves as a checkpoint that optimizes cooling and homogenization of the rubber mixture prior to commencement of a subsequent rubber production process.

Each rail 124, 126 should be configured to provide a water flow rate as determined by the mixing recipe of the selected rubber mixture. In some processes, the predefined water flow rate may be from about 70 liters/hour to about 400 liters/hour. Similarly, each aspiration hood 134, 136 should be configured to provide a predefined air flow rate as determined by the selected rubber mixture recipe. In some processes, the aspiration of air is selected at a level from about 5000 m ³ /hr to about 30000m ³ /h.

The flow rates of water and aspiration of air may vary as long as the delivered flow rates confer to the rubber mixture the target values of temperature and water content before adding the crosslinking ingredients. For example, if, after an elapsed time, the rubber mixture temperature is greater than an expected target temperature, the water flow rate (for example, as delivered by rail 124 or rail 126) can be adjusted to a higher rate than would be delivered at a lower temperature. In some processes, the target temperature of the rubber mixture is about 70° C, at which temperature the predictability and reproducibility of the process are obtained. In some processes, the target water content does not exceed about 0.20% by mass of the rubber mixture.

The adjustment of the water flow rate can be performed alone or in combination with an adjustment of the air flow rate (e.g., by the aspiration hood 134 or the aspiration hood 136). As successful adjustments are made over time, such adjustments may be repeated to ensure that the water content of any rubber mixture is limited to the target value therefor. This value is ensured prior to the subsequent addition of vulcanization ingredients. Such a control allows predictable and reproducible mixing cycles with reduced cycle times relative to the surrounding atmospheric conditions. Referring again to Figure 1, continuous sheet 112 is transported to a transport installation 200 that performs the selective transfer of sheet 112 to a preselected rubber mixture production installation. Transport installation 200 includes an optional evacuation station 206 having a spray system and an aspiration system for effecting an auxiliary cooling process as described above with respect to mixing and cooling installation 100. As further illustrated in FIG. 2, evacuation station 206 includes at least one spray rail 224 having nozzles which are positioned to spray sheet 112 at a predetermined water flow rate. Rail 224 includes a similar configuration to that described above with respect to rails 124, 126. At least one aspiration hood 226 is downstream of spray rail 224 and has a similar configuration to that described above with respect to aspirations hoods 134, 136. Aspiration hood 226 is positioned to aspirate air after spraying by rail 226.

When evacuation station 206 performs additional cooling of the sheet, rail 224 sprays water thereon for evacuation by aspiration hood 226. The cooling process performed at evacuation station 206 ensures that the rubber mixture exhibits a sufficient temperature and water content for sequential execution of a process in a monopassage or multipassage sequence. In other words, the sheet has properties suitable for the execution of a subsequent process, irrespective of whether the process is part of a monopassage sequence or a multipassage sequence.

In step D, for both monopassage and multipassage sequences (see FIGS. 1 and 3 to 5), performed at the level of transport installation 200, a transport means such as an evacuation belt 240 transports sheet 112 from mixing and cooling installation 100 toward a retractable conveyance 250 or a conveyance 252, which are available at the level of transport installation 200. In some sequences, sheet 112 is maintained at the level of transport installation 200 prior to performing a subsequent process. The sequential direction of the rubber mixture toward a preselected rubber mixture production installation depends upon the selected rubber mixture. In this manner, system 10 realizes the benefits of both monopassage and multipassage sequences while permitting a selection between the two.

The pre-selected rubber mixture production installation is selected from a

complementary mixing installation 300 that performs a complementary mixing process and an end-of-line installation 400 that performs at least one end-of-line process. The complementary mixing installation 300 realizes both monopassage and multipassage sequences and includes at least one ramless mixer 302 having a chamber 304 of a predefined filling volume. In some embodiments, the mixer 302 has a fill volume approximately twice that of internal mixer 22 positioned at initial mixing installation 20. Ramless mixer 302, which includes one or more mixing blades (not shown) as is known in the art, may be selected from commercially available mixers.

End-of-line installation 400, which is used for both monopassage and multipassage sequences, includes equipment for performing an end-of-line line process. This end of line process can be selected from profiling, sampling, processing, cooling, palletizing and storage of the rubber mixture. Equipment that is installed to perform the end of line process can be combined with other end-of-line equipment as needed.

Referring further to FIGS. 3, 4 and 5, retractable conveyance 250 may be positioned for selective transfer to complementary mixing installation 300 or for selective transfer to end-of-line installation 400. During step D of a monopassage sequence (see FIG. 3), retractable conveyance 250 extends toward evacuation belt 240 to allow the continuous conveyance of sheet 112 towards complementary mixing installation 300. In such sequences, retractable conveyance 250, either alone or in combination with another conveyance, dispatches the rubber mixture for performance of a complementary mixing process.

In further reference to FIG. 4, at step D of a multipassage sequence, and in particular for one or several successive passes (i.e., the passages of the sequence before the last passage), retractable conveyance 250 withdraws from evacuation belt 240 for uninterrupted conveyance of sheet 112 to end-of-line installation 400. Conveyance 252 performs the selective transfer in by-passing complementary mixing installation 300 and transporting sheet 112 directly to end-of-line installation 400. The choice between a monopassage or a multipassage sequence therefore determines whether retractable conveyance 250 is positioned to bypass the complementary mixing installation.

System 10 eliminates non-conforming mixtures in both monopassage and

multipassage sequences. While the processes reduce any possibility of waste, in the case of a non-conforming material (e.g., due to a malfunction of a mixing process), the system can prevent the material from reaching complementary mixing installation 300. Consequently, additional waste of energy and time is avoided while the advantages of different rubber mixture production sequences are preserved.

Another advantage of the disclosed configuration is to allow the realization of certain mixtures with similar properties compared to the same mixtures obtained with known methods (such as internal mixer and external mixer) while optimizing the amount of energy supplied to the mixture. Preferably, the method according to the invention is used to lower the specific energy of an elastomeric material comprising natural rubber, preferably more than 25% by weight relative to the total weight of the elastomeric material. More preferably, the natural rubber is 50%, 60%, 70%, 80%, 90% or even 100% by weight relative to the total weight of the elastomeric material.

By way of example, the following comparative results were obtained for a final rubber composition as described in the table below:

TABLE 1

The control results are obtained with the aid of a control method for a monopassage sequence of the internal and external mixer type (at this stage, introduction of the crosslinking system), the main operating parameters of which are summarized below.

The rubber compositions of the control and the mixture were obtained with the process adjustments as described in the tables below.

The main operating parameters of the process according to the invention are summarized below. Process of the

Control process

invention

First internal mixer

Drop temperature(°C) 160 160

Filling coefficient 80 80

Mixing time (min) 2Ί0 2Ί0

Rotor speed (t/min) 50 50

External mixer

Mixing time (min) 9 5

Gap distance (mm) 3 4

Cylinder diameter(mm) 860 860

Cylinder 1 speed (t/min) 30 30

Cylinder 2 speed (t/min) 30 30

Second internal mixer

Drop temperature(°C) N/A 105

Filling coefficient N/A 45

Mixing time (min) N/A 2

Rotor speed (t/min) N/A 20

Module at 10% 100 100

ML(l+4) 100°C 100 100

Fluidity 100 100

Fixation at 130°C 100 100

Supplied specific energy 100 80

TABLE 2

By "module at 10%" is meant the modulus of elongation of a specimen of the rubber composition after vulcanization at 150° C.

These measurements are carried out in accordance with the French standard NFT 46-002 of September 1988 that provides the measurement in first elongation (i.e., without accommodation cycle, the modules are then denoted M) of true secant modules (i.e., calculated by reducing to the actual section of the test piece), expressed in MPa, at 10%> elongation. These tensile measurements are carried out under normal conditions of temperature and hygrometry (23° C +/- 2° C, 50 +/- 5% relative humidity, French standard NF T 40-01 of December 1979).

The specific energy, supplied to the rubber composition during the manufacturing process in a mixing means, corresponds to the energy (in joules) supplied to the mixture, divided by the mass of the rubber composition made by the process. In order to avoid alteration of the physical properties imparted to the initial composition, the operating parameters of the series of rubber mixing installations are selected continuously so that the specific energy supplied to the rubber composition at the outlet of the second internal mixer (302) is lowered by about 20% with respect to the specific energy supplied to a composition coming out of a single-shot control process.

Fluidity

This measurement is adapted from the fluidity measurement commonly used in the plastics industry for the characterization of extrudability including thermoplastic materials. The measurement is described in ASTM D1238 (or NF T 51-016), and modified as follows. The operating parameters of the mixing installation are chosen so that the fluidity of the rubber composition at the outlet of the installation is improved by about 25% with respect to the fluidity of a composition leaving the installation pursuant to a control method without spraying.

In a capillary rheometer, the sample of the elastomer mixture is heated to a controlled temperature (about 90 ° C). The eluted mass (extrudate) is then measured through a cylindrical die (diameter 2 mm) of tungsten carbide by means of a loaded piston. The fluidity value corresponds to the displacement of the piston under the effect of the load, in hundredths of mm for a time of 10 seconds (it corresponds to a flow). The index 100 is given for the fluidity of the control composition, with an index greater than 100 indicating a greater fluidity, and a lower index indicating less fluidity.

Viscosity

The "Mooney" viscosity, also known as viscosity or plasticity, characterizes, in a known manner, solid substances. Use is made of an oscillatory consistometer as described in ASTM standard D1646 (1999). The Mooney plasticity measurement is carried out according to the following principle: the sample, analyzed in the raw state (i.e., before curing), is molded (formed) in a cylindrical chamber heated to a given temperature (for example, 35° C or 100° C). After preheating for one minute, the rotor rotates within the test specimen at 2 rpm, and the torque needed to maintain this movement is measured for 4 minutes of rotation. The Mooney viscosity (ML 1 + 4) is expressed in "Mooney unit" (MU, with 1MU = 0.83 Nm) and corresponds to the value obtained at the end of the 4 minutes. Scorch Time

The scorch time (noted T5) is also measured, at 130° C, according to the French standard NF T 43-005 (1991); the variation of the consistency index as a function of time also makes it possible to determine this scorch time of the rubber compositions, evaluated according to the aforementioned standard, by the parameter T5 (case of a large rotor), expressed in minutes, and defined as the time required to obtain an increase in the

consistometric index (expressed in MU) of 5 units above the minimum value measured for this index. Dosage of the water:

The Karl-Fisher method is used.

Referring further to FIG. 5, during step D of a multipassage sequence and particularly during the last passage thereof, retractable conveyance 250 extends toward evacuation belt 240 for uninterrupted transport of sheet 112 towards complementary mixing installation 300. At this stage, the rubber mixture has already been transferred to end-of-line installation 400 and subject to the execution of an end-of-line process. In some multipassage sequences with successive passages before the last passage, the rubber mixture returns to the beginning of another sequence at initial mixing installation 20 (for example, starting from step B of FIG. 4). In some multipassage sequences, one or more rubber mixtures are available at the end-of- line installation 400. One or more of these mixtures may be extracted and combined during a later passage (for example, by starting from step B of FIG. 4). For such sequences, evacuation station 206 performs further cooling steps to ensure that the water content and the temperature of any rubber mixture are restricted to target values prior to introduction of vulcanization ingredients during the complementary mixing process.

In a step E of both a monopassage sequence (see FIG. 3) and a last pass of a multipassage sequence (see FIG. 5), performed at complementary mixing installation 300, mixer 302 receives one or more complementary ingredients (e.g., crosslinking or vulcanizing ingredients) that form the crosslinking system and any complementary elastomers and necessary additives (e.g., additional elastomers and/or recycling materials 309, protection agents 311 and crosslinking agents 313). In some processes, complementary ingredients include at least one of sulfur and one or more accelerators. It is understood that other complementary ingredients can be introduced into mixer 302. In a step F of both a monopassage sequence (see FIG. 3) and a last passage of a multipassage sequence (see FIG. 5), performed at complementary mixing installation 300, mixer 302 performs the complementary mixing process. During this process, mixer 302 mixes sheet 112 with the complementary ingredients to effect mixing of all ingredients. Upon delivery of sheet 112 to the complementary mixer, the rubber mixture has already reached the target values of temperature and water content.

During the complementary mixing process, the temperature of the rubber mixture is controlled as is known in the art (for example, by adjusting the speed of the mixing blades of mixer 302, by employing a low filling factor, etc.). In some methods, the temperature of the mixture in chamber 304 is regulated so as not to exceed 120° C prior to delivery of the rubber to end-of-line installation 400. In some processes, this temperature is controlled so as not to exceed about 110 ° C.

In a step G of both a monopassage sequence (see FIG. 3) and a multipassage sequence (see FIGS. 4 and 5), performed at end-of-line installation 400, an end-of-line process can be performed as is known in the art. For monopassage sequences, step G is performed after completion of the complementary mixing process by complementary mixing installation 300 (see step G of FIG. 3). For multipassage sequences, step G is performed after the mixing and cooling process executed at installation 100 and without performing the complementary mixing process at complementary mixing installation 300 (i.e., after transfer of sheet 112 from evacuation station 206) (shown in FIG. 4). For multipassage sequences, step G is repeated after performance of the complementary mixing process at complementary mixing installation 300 (shown at step G of FIG. 5).

Thus, during multipassage sequences and before the final passage thereof, sheet 112 is transferred to end-of-line installation 400 without passing the sheet to mixer 302. This bypass of the complementary mixing installation avoids contamination of the rubber mixture by a crosslinking residue that may remain in chamber 304. Although the complementary ingredients are deliberately selected to perform efficient crosslinking, contamination with crosslinking residues is preferably avoided for recipes in which the rubber mixture requires an additional processing (e.g. at one or more of an end-of-line installation 400, a mixing and cooling installation 100 and an optional evacuation station 206).

System 10 includes a transport means that sequentially directs the rubber mixture to one or more of the rubber mixture production installations. As used herein, the term "transport means" or "conveyance" refers to one or more transport means or conveyances such as belts 114, 116, 240, transport installation 200, retractable conveyance 250 and equivalent and complementary transport means and conveyances. It is understood that the transport means is not limited to continuous belts and that other conveyances may be used for this purpose without departing from the scope of the present invention. The transportation can be "endless" (i.e., uninterrupted) for at least one sequence in progress and may circulate endlessly through one or more successive sequences.

The present invention contemplates the creation of rubber mixture production installations in which the rubber mixture production processes are selectively performed according to a selected rubber mixture recipe (e.g., by one or more controllers). These examples of rubber mixture production installations can follow a programmed sequence. For example, a central control center 230 (shown in FIG. 2) may be programmed with established data for a plurality of rubber mixtures, each having a unique mixing cycle profile (e.g., monopassage sequence or multipassage sequence). Additional data may include at least one predefined water flow rate to deliver for each spray rail, an air flow rate to deliver to each aspiration hood, a target temperature of the rubber mixture after an elapsed time and a target water content for the rubber mixture.

One or more sensors and/or sensor types may be optionally employed, including but not limited to environmental sensors (e.g., to sense atmospheric conditions such as

temperature, pressure and/or humidity prior to initiation of a mixing cycle) and verification sensors (e.g., to sense deviation from a proscribed sequence). In this manner, the presently disclosed invention enables an increased number and variety of rubber mixtures to be produced in view of the tire to be manufactured.

While one tire may benefit from a rubber that has its properties influenced by a monopassage rubber production sequences, another tire may benefit from a rubber that has its properties influenced by a multipassage rubber production sequence. Comparable ingredients may be used for both types of sequences and are therefore amenable to manufacture on equipment that accommodates various other non-disclosed processes. Such equipment can incorporate additional beneficial rubber mixing treatment processes without compromising the quality of the resulting rubber mixture and ultimately the performance of the final product.

It is understood that one or more steps in a selected monopassage or multipassage sequence can be performed at a given time and for a fixed duration. To support the modularity of production capacity, one or more systems can be installed at a common facility with commencement of certain steps being staggered between installations (e.g., a cooling process of one system can begin within a predefined waiting time after the commencement of a cooling process by another system in the same facility). The present invention likewise contemplates equilibration of one or more steps or processes in the same system. A start time for one or more steps may be staggered in relation to a start time for other steps in the same sequence. One or more steps may conclude upon commencement of a subsequent step or may otherwise have their durations extended until the conclusion of consecutively performed step.

At least some of the various techniques described herein may be implemented in connection with hardware or software or, where appropriate, with a combination of both. For example, electrical data processing functionality may be used to implement any aspect of power computation and adjustment, including implementation in connection with a computing device (including a mobile networking apparatus) that includes hardware, software, or, where appropriate, a combination of both.

The terms "at least one" and "one or more" are used interchangeably. Ranges that are described as being "between a and b" are inclusive of the values for "a" and "b."

While particular embodiments of the disclosed apparatus have been illustrated and described, it will be understood that various changes, additions and modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, no limitation should be imposed on the scope of the presently disclosed invention, except as set forth in the accompanying claims.