The invention generally relates to the production of products prepared from a rubber mixture. More particularly, the invention relates to an extrusion device for producing a product in the form of a thin strip from a rubber mixture.
In the field of production of products prepared from a rubber mixture (including tires), use is made of devices for making a profiled product based on a rubber mixture in the form of a very thin strip. The strip made may be very wide and may be deposited directly on a known device (including a tire building drum, or “drum”), or directly superposed at the outlet of the device upon another material (for example, one or more plies or layers already deposited on the drum).
One recognized solution used to obtain this result is the extrusion device 10 shown in
During production, a rubber mixture is subjected to considerable stresses. With reference to
Since a strip emerging from an extrusion device of the type shown in
The invention relates to an extrusion device for forming as a thin strip a product based on a rubber mixture, the device including a rotating roller, an inlet orifice allowing the rubber mixture to flow and a vault circumferentially covering at least part of an outer surface of the roller, the vault having a wall bearing, on its inner surface oriented towards the roller, projecting threads so as to delimit with the surface of the roller a chamber for plasticizing the rubber mixture, the rubber mixture being driven from the inlet orifice towards an extrusion orifice into a gap defining the profile of the product, delimited by the wall of the vault and the outer surface of the roller, characterized in that:
In one embodiment of the extrusion device, the extrusion device further includes an extrusion plate that adjustably delimits, with the outer surface of the roller, the extrusion orifice.
In one embodiment of the extrusion device, each striation has a cross section of predetermined geometry, with a rounded shape at the bottom of each striation, and with pointed edges.
In one embodiment of the extrusion device, an angle between the edges of the striations and the outer surface of the roller is less than or equal to 90°.
In one embodiment of the extrusion device, the striations have a triangular cross section.
In one embodiment of the extrusion device, the projecting threads include:
In one embodiment of the extrusion device, the gap defining the profile of the product defines a product thickness of less than 5 mm.
In one embodiment of the extrusion device, the vault is pivotably mounted about an axis of rotation borne by a support element of the roller.
The invention also relates to a process for forming the rubber mixture produced by the disclosed extrusion device, the process including the following steps:
The invention also relates to a tire production line, including at least one extrusion device of the type disclosed, arranged downstream of at least one extruder for extruding the rubber mixture.
Further aspects of the invention will become obvious from the following detailed description.
The nature and various advantages of the invention will become more evident from reading the following detailed description, and from studying the attached drawings, in all of which the same reference numerals denote identical parts, and in which:
Referring now to the figures, in which the same numbers identify identical elements,
It is understood that a rubber mixture (or “mixture”) introduced into the device 100 may include all materials necessary for producing the product, including, without limitation, an elastomer (for example, a natural rubber, a synthetic elastomer and combinations and equivalents thereof) and one or more ingredients, such as one or more processing agents, protective agents and reinforcing fillers. The materials may also include one or more other ingredients such as carbon black, silica, oils, resins and crosslinking or vulcanization agents. During mixing of the rubber mixture, all ingredients are introduced in variable quantities depending on the performance desired from the products obtained by the mixing processes (for example, the tires).
Still with reference to
The device 100 further includes a vault (not shown) of the type included in the device 10 of
It is understood that the vault is not divided into sectors but has at least two projecting threads extending substantially axially from the wall (“axial threads”). These two axial threads guide the mixture towards the extrusion orifice, distributing it over the width of the extrusion orifice. Other projecting threads in the vault may be oriented (“oriented threads”) in different directions, such as helical threads or convergent or divergent threads, relative to the axial threads.
Two flanges 116, 118 are mounted respectively on the two shoulders 112c, each flange axially bearing internally a shoulder (not shown) that interacts respectively with a corresponding end of the vault. This allows the vault to be secured to the device by one or more known securing means (for example, one or more screws or one or more equivalent means).
As can be seen in
It is understood that an extrusion plate (or “plate”), of the type described above in relation to
The roller 112 incorporates a means for controlling the temperature inside the roller, this means including, for example, a network including one or more feed channels 125 passing through the roller and one or more conveying grooves 127 (see
Still with reference to
Each striation 112Ra forms a channel with a cross section of predetermined geometry (for example, triangular, circular, substantially rectangular, etc. cross section). A rounded shape is delimited at the bottom of each striation 112Ra, and pointed edges scrape the material during plasticization. An angle between the edges of the striations and the outer surface 112a of the roller 112 is, preferably, 90° or less.
The roller 112 and the vault of the device 100 are assembled such that the crests of threads created by the continuous helix are tangential to the crests of threads on the vault. In other words, the crests are substantially in contact with one another. It is said that the crests are “substantially in contact” when the crests face one another with such a small space between them that a rubber material cannot catch on the surfaces of the crests, thereby preventing the formation of particles in the thin strip formed from the mixture. Thus, no product can get stuck on an outer surface 112a of the roller 112 or on the wall of the vault without being pushed by a thread as it rotates.
During a process for forming the mixture, the rubber mixture is introduced into the device 100 via the inlet orifice. As it continues to rotate, the roller 112 conveys the mixture entering in the peripheral direction (see the arrow B in
The rubber mixture continues to pass through as far as the extrusion orifice, where the plasticized rubber mixture is taken by the plate so as to subsequently emerge from the device 100 in the form of a thin strip. A “thin strip” is said to correspond to a strip with a thickness of less than 5 mm (in so far as the plasticization of the rubber mixture by the device is necessarily limited by the nature of the tool). In some embodiments of the device 100, this thickness is around 0.3 mm at the outlet of the device 100. A thicker strip could be produced, depending on the nature of the rubber mixture and the form in which it is introduced into the inlet orifice of the device (for example, using a mixture already worked prior to being introduced).
By virtue of the groove 112R in the roller 112, any potential particles produced during a process for forming the mixture are removed from the thin strip emerging from the device 100. All of the material can be treated regularly and moderately, producing a very homogeneous end product that can be placed directly on a building drum or form.
It is understood that the device 100 may be arranged at the outlet of at least one extruder such that a mixture emerging from the extruder is directed towards the inlet orifice of the device. It is also understood that the device may be incorporated in a production line with an extruder for extruding several rubber mixtures and at least two devices 100 arranged downstream so as to allow several products (in other words, thin strips) to be deposited successively on a building drum. In one embodiment of a production line incorporating the device 100, the mixture may pass between the rollers of a roller-die type system arranged just downstream of the extruder and upstream of the device 100. In this embodiment, the rotation of the rollers may be managed by the quantity of mixture supplied (detected, for example, by a proximity sensor, by a pressure sensor or by an equivalent device) so as to form a continuous ply of predetermined thickness and width.
For all embodiments of the device 100, a monitoring system could be installed. At least one part of the monitoring system may be supplied in a portable device such as a mobile network device (for example a mobile telephone, a laptop computer, a camera, one or more portable devices connected to the network (including “augmented reality” and/or “virtual reality” devices, portable clothing connected to the network and/or any combinations and/or any equivalents)).
In embodiments of the invention, the device 100 (and/or an installation or a tire production line incorporating the device 100) may receive voice commands or other audio data (representing, for example, a start or stop of the process for forming the mixture). The request may include a request for the current state of a process for forming the rubber mixture. A response generated can be represented audibly, visually, in a tactile manner (for example by way of a haptic interface) and/or in a virtual and/or augmented manner.
In one embodiment, the process for forming the mixture performed by the device 100 of the invention may include a step of training the device 100 (or of training an installation or a tire production line incorporating the device 100) to recognize values representative of the thin strip (for example, values of length, width and thickness relative to the particles detected and removed) and to compare them with expected values. This step may include the step of training the device 100 to recognize a lack of equivalence between the compared values. Each training step may include a classification generated by self-learning means. This classification may include, without limitation, the parameters of the selected rubber mixture recipe, the durations of the processes for forming the mixture and the expected values during an ongoing tire production cycle. The data obtained may be fed into one or more neural networks that manage the device 100 and/or one or more installations or production lines incorporating the device 100.
The terms “at least one” and “one or more” are used interchangeably. The ranges given as lying “between a and b” encompass the values “a” and “b”.
Although particular embodiments of the disclosed apparatus have been illustrated and described, it will be appreciated that various changes, additions and modifications can be made without departing from either the spirit or scope of the present description. Therefore, no limitation should be imposed on the scope of the invention described, apart from those set out in the appended claims.
Number | Date | Country | Kind |
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2011398 | Nov 2020 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/080090 | 10/29/2021 | WO |