INJECTOR FOR INJECTING LIQUID CONSTITUENTS INTO AN INTERNAL MIXER AND RELATED METHOD

Abstract

An injector (10) is used to introduce liquid products other than a rubber compound into a chamber of an internal mixer in which the injector (10) is mounted. A mixing system for performing mixing cycles of a rubber compound is also described; this mixing system includes the injector and the internal mixer in which the injector is mounted. A related mixing cycle performed by the mixing system is also described.

Description

INJECTOR FOR INJECTING LIQUID CONSTITUENTS INTO AN INTERNAL MIXER AND RELATED METHOD Field of Invention The invention relates to an injector that allows liquid products to be introduced into an internal mixer chamber. More specifically, the invention relates to the injection of different liquid products through the same injection orifice without them mixing. Background of the Invention In the field of rubber compound manufacturing, internal batch mixers of the Banbury type (and their equivalents) are well known for producing rubber compounds. During a mixing cycle performed by the internal mixer, various raw materials can be fed into the mixer. These raw materials include those required to produce the final product from a single mixing cycle, including, but not limited to, an elastomeric material (e.g., natural rubber, synthetic elastomer, and combinations and equivalents thereof) and one or more ingredients, such as one or more processing agents, protective agents, reinforcing fillers, and / or crosslinking or vulcanizing agents. All ingredients are introduced in varying quantities. Ref. 331922, depending on the desired performance of the products obtained from the mixing cycles (e.g., tires). The raw materials could also include one or more liquid products, including but not limited to silane, antioxidants (e.g., 6PPD), wax, and stearic acid. Therefore, multi-way injectors are available on the market that simultaneously introduce several different liquid products into an internal mixer chamber. However, most of these injectors cause undesirable mixing of the liquid products before they are introduced into the internal mixer. Furthermore, several solutions exist on the market that prevent the mixing of liquid products. One such solution, a multi-way injector, is offered by Zeppelin Systems (Zeppelin) as part of an automated product dosing system (or liquid dosing system, or LDS) (a model of this system can be found at https: / / www.zeppelin-systems.com / videos.html). In Zeppelin's system, each liquid product is stored in a separate tank connected to the injection point dedicated to dosing that specific product. While the number of injection points is multiplied while maintaining a small diameter, simultaneous injection of different liquid products is not easily and quickly possible. Consequently, the flow rates achievable with this system remain limited. With the aim of achieving faster injection of liquid products compared to existing solutions, the described invention allows for the simultaneous injection of several different liquid products without them mixing. The invention also incorporates circulation channels for the heat transfer fluid, enabling temperature control of the injection chamber depending on the liquid products being processed (thus controlling heating or cooling based on the specific liquid product used). This makes it possible to distribute, through the same mixer orifice, products that are otherwise incompatible and could not be used in an injector that brings them into contact before their introduction into the mixing chamber of an internal mixer. Summary of the Invention The invention relates to an injector for introducing liquid products other than a rubber mixture into a chamber of an internal mixer in which the injector is mounted, characterized in that the injector includes: a cylindrical housing of a predetermined length between an injection end and an opposite end of the injector, the housing having at least two injection ducts, with each injection duct dedicated to the flow of a liquid product to form the mixture, each injection duct extending between an injection duct outlet, which is coextensive with the injection end of the housing and an opposite inlet, and each injection duct having a defined seat adjacent to the outlet; - a valve located in each injection duct that measures a corresponding liquid product, the valve includes a longitudinal stem extending between a rear portion located adjacent to the injection duct inlet and a head located adjacent to the injection duct seat; - a return spring located around the valve stem that handles the sliding movement of the valve relative to the injection duct between a closed position, where the head engages with the seat and blocks the outlet of the injection duct, and an open position, where the head no longer engages with the seat and unlocks the outlet of the injection duct; an injection device integrated with the housing and including a supply conduit that supplies a liquid product to a corresponding injection conduit of a reservoir in which the liquid product is stored, each supply conduit being placed perpendicular to a corresponding injection conduit to introduce the liquid product into the inlet of the injection conduit; and - a temperature control circuit inside the injector. In certain injector models, the temperature control circuit includes: - at least two control channels that extend axially along part of the length of the housing into the injection device; at least one control conduit located in the injection device that carries a corresponding temperature control fluid to the injector, the control channels being connected to the control conduit; and a pipe from the injection device that introduces the temperature control fluid into a corresponding control conduit from a source of the temperature control fluid. In certain injector designs, the housing includes at least three injection channels and the injection device includes a supply channel corresponding to each injection channel. In certain injector models, the injector includes at least three control channels. In certain injector models, the control channels and piping are connected so that the temperature control fluid flows continuously in the temperature control circuit within the injector. The invention is also applied to a mixing system for performing the mixing cycles of a rubber mixture; the system includes an injector as described and an internal mixer in which the injector is mounted. The invention is also applied to a mixing cycle performed by the described mixing system, which includes the following stages: - an injection stage of the liquid products into the internal mixer through the injector, during which the liquid products are dosed according to the selected rubber mixture recipe; - a temperature control stage that includes a stage for introducing one or more temperature control fluids into the temperature control circuit within the injector; and - a mixing stage, in the internal mixer, of the different liquid products injected by the injector and other raw materials to form the mixture. In certain cycle modalities, the temperature control stage is performed before the liquid product injection stage. In certain cycle modalities, at least one of the liquid product injection stage and the temperature control stage is performed iteratively during the mixing cycle. In certain cycle modes, the raw materials introduced during the mixing stage include at least one elastomer material. Other aspects of the invention will become clear from the following detailed description. Brief Description of the Figures The nature and distinct advantages of the invention will become more obvious when the following detailed description is read, together with the accompanying figures, in which the same reference numbers designate identical parts everywhere and in which: Figure 1 shows a perspective view of one modality of an injector of the invention. Figure 2 shows a cross-sectional view along line AA of Figure 1. Figure 3 shows a partial transparent view and Figure 4 shows a partial cross-sectional view of the injector in Figure 1. Figure 5 shows an unassembled view of an injector temperature control circuit from Figure 1. ) 7Q7f\r\l77f\7l^iyi Detailed Description of the Invention The following figures, in which the same numbers identify identical elements, are shown in Figures 1 and 2, which depict a variant of a multi-way injector (or injector) 10 that introduces liquid products into a chamber of an internal mixer. The injector 10 is suitable for installation in internal mixers commonly used for rubber compounding. The term internal mixer (or mixer or MI) refers to mixers of the Banbury type and their equivalents. The injector 10 includes a multi-way injector incorporating at least two channels, each dedicated to a specific liquid product. The term multi-way means that the injector is capable of dispensing at least two different liquid products into an internal mixer during a single mixing cycle.In some embodiments of the invention, the injector 10 is capable of dispensing at least three different liquid products from their respective storage media into the internal mixer in which the injector is mounted. It is understood that dispensing all the different liquid products simultaneously is not mandatory. Any of the available liquid products may be dispensed according to the selected rubber mixing recipe. It is also understood that the dispensing of the liquid products may be carried out either in a preferred order or simultaneously, depending on the selected rubber mixing recipe. The injector 10 includes a cylindrical housing (or cavity) 12 of a predetermined length between an injection end 12a and an opposite end 12b of the injector. The housing 12 includes at least two injection passages 14, with each injection passage 14 dedicated to the flow of a liquid product from a reservoir in which the liquid product is stored. Each injection passage 14 extends between the outlet 14a of the injection passage, which is coextensive with the injection end 12a of the housing 12, and an opposite inlet 14b. A seat 14c is defined opposite the outlet 14a. In the injector 10 configuration shown in the figures, the injector 10 has three injection channels 14. It is understood that the number of injection channels can be varied according to the selected rubber compound and / or the internal mixer used (for example, two, three, or more injection channels may be expected). Consequently, the injector 10 can accommodate several different liquid products simultaneously, regardless of the properties of the liquid products (for example, varying viscosities). A valve 16 is placed in each injection conduit 14 to meter a corresponding liquid product. The valve 16 includes a longitudinal stem 16a that extends between a back portion 16b and a head 16c located adjacent to the seat 14c of the injection conduit 14. A return spring 18, situated around the stem 16b of the valve 16, controls the sliding movement of the valve relative to the injection conduit 14 between a closed position (shown in Figures 1 and 2), where the head 16c conforms to the shape of the seat 14c and blocks the outlet 14a of the injection conduit 14 (preventing the supply of the liquid product to the internal mixer), and an open position (not shown), where the head 16c is no longer in contact with the seat 14c and the outlet 14a of the injection conduit 14 is unblocked (allowing the liquid product to be metered to the internal mixer). The configuration of injection port 14 with valve 16 positioned inside is shown as an example. The other injection ports and injector valves 10 have the same configuration as shown in Figures 1 and 2 and therefore operate identically. The cross-sectional diameters of the injection ports 14 can be adjusted according to the selected rubber blending recipe. These dimensions are selected to ensure the correct dosage in the internal mixer. Furthermore, the return spring tension 18 can be selected or adjusted (e.g., by means of a known screw system for adjusting spring tension) depending on the viscosity and dosage of the liquid products to be fed into the internal mixer. With reference once again to Figures 1 and 2 and also to Figures 3-5, the injector 10 also includes an injection device 20. The injection device 20 is associated with the housing 12, such that it allows the injection of different liquid products and also includes means for circulating the temperature control fluids (or control fluids) in the injector 10. The term temperature control means either the cooling or heating of a liquid product for the purpose of achieving the desired viscosity of the liquid product. The temperature of a temperature control fluid may be varied during a mixing cycle to ensure the continuous flow of the liquid product through the injection channels 14 and also to ensure the complete injection of the liquid product into the internal mixer. To introduce the liquid products necessary to perform the selected rubber mixing recipe, the injection device 20 includes a supply line 22 corresponding to each injection line 14 of the injector 10. In the injector 10 configuration shown in the figures, the injection device 20 includes three supply lines 22 (one supply line 22 is associated with each injection line 14). It is understood that the number of supply lines may vary according to the number of injection lines. Each supply line 22 delivers a corresponding liquid product (such as, but not limited to, silane, antioxidants (e.g., 6PPD), wax, and stearic acid) to the injection line 14 of a storage tank (not shown) that holds the liquid product being supplied (the liquid product is transported from the tank to the supply line by piping or equivalent known means). Depending on the mixture selected for blending in the internal mixer, each liquid product is metered as it leaves the storage tank. A known metering means (e.g., using pumps and control means such as mass flow meters) is used so that a precise dose of the liquid product arrives in the supply line 22 before it is introduced into the injector 10. Each supply line 22 is positioned perpendicular to a corresponding injection line 14 to introduce the liquid product into the inlet 14b of the injection line 14. The inlet is positioned relative to the valve 16 between the rear portion 16b and the head 16c. The pressure at which the liquid product exits the supply line 22 is sufficient to overcome the force of the return spring 18 in order to disengage the head 16c from the seat 14c of the injection line 14. The valve 16 moves from the closed to the open position to inject the dose of liquid product into the mixing chamber of the internal mixer (see arrow A in Figure 2). When the injection of the liquid product is complete, the return spring 18 returns the head 16c to the seat 14c so that the valve 16 can return to the closed position.The precise dosing of the liquid product is guaranteed by injector 10. In this way, during the mixing cycles, the precise injection of the liquid products into the internal mixer is guaranteed. With reference once again to Figures 1-5, the injector 10 has temperature control channels 26 (or control channels) that extend axially along part of the length of the housing 12 inside the injection device 20. The control channels 26 are positioned along the housing 12 (see Figure 4) and are connected to the temperature control conduits 28 (or control conduits) provided in the injection unit 20. For the embodiment shown, the injector 10 has three control channels 26, although the number of control channels can be adapted as required. Each control channel 28 carries the corresponding control fluid to the injector 10 (and more specifically, to the injection device 20 and housing 12) (see Figures 4 and 5). The control fluid is introduced into each control channel 28 through a pipe 30 from a temperature control system (not shown) using a known control fluid (such as water, steam, gas, or another known temperature control fluid). The control channels 26, control channels 28, and pipes 30 together form a temperature control circuit within the injector 10 to control the temperature of the liquid products to be injected during a mixing cycle. With reference to Figure 5, a representative control fluid flow is given as an example. A first pipe 30a (shown in Figure 3) introduces control fluid into the corresponding first control conduit 28a (see arrow C in Figure 5). The first control conduit 28a carries the control fluid from the injection device 20 to a corresponding control channel 26a. The control fluid flows through the control channel 26 until it reaches a junction channel 29 between the first control conduit 28a and a second control conduit 28b (see arrow B in Figure 5, which corresponds to arrow B in Figure 4). The control fluid continues to flow through the control channel 26 to a plug 32 that directs the fluid flow from the junction channel 29 into the second control conduit 28b (see arrow D in Figure 5).In this example, the control fluid flowing through the second control pipe 28b (see arrow E in Figure 5) enters a second pipe 30b (shown in Figure 3). Finally, the control fluid exits the second pipe 30b into a third pipe (not shown) and is once again directed to injector 10 (for example, by installing a control line between the second and third pipes). In some embodiments of injector 10, the temperature control circuit is said to be in series when the same volume of control fluid can flow through the entire circuit (the term circuit means the control channels 26, the control ducts 28, and the pipes 30). In other embodiments of injector 10, an individual volume of control fluid can be introduced into the injector 10 and can flow out of the control system through a single control duct 28. The injector 10 configuration allows for quick adjustment between modes. A mixing system (or system) of the invention includes the injector 10 and the internal mixer in which the injector is mounted. The system performs a mixing cycle of a rubber compound that includes a stage of injecting the liquid products into the internal mixer through the injector 10. During this stage, the liquid products are dosed according to the selected rubber compound recipe. The mixing cycle performed by the system also includes a temperature control stage, which involves introducing the temperature control fluid(s) into the control channels 26. This stage can be performed before the injection of the liquid products so that the control channels 26 can regulate the temperature of the housing 12 in advance of the liquid products being introduced into the injection channels 14. In this way, the housing 12 has already reached the desired temperature as a function of the liquid products before their introduction. It is understood that this stage can be performed after or simultaneously with the liquid product injection stage. The liquid product injection stage and the temperature control stage can be performed repeatedly during the mixing cycle. In some configurations of the mixing system, the control lines 28 and pipes 30 can be connected so that the control fluid flows continuously in the temperature control circuit within the injector 10. ! 7Ά7.MM7.7.(\7.ΐνΓ* The mixing cycle performed by the system also includes a mixing stage, in the internal mixer, of the different liquid products injected by injector 10 and the different raw materials to form the mixture. During this stage, all ingredients are introduced in varying quantities according to the desired yield of the products obtained from the mixing cycle (e.g., tires). At the end of the mixing cycle, the product is finalized by blending and can be used in a downstream process (which could be, for example, a palletizing process, a forming process, and / or another mixing process and / or an extrusion process). The dosing of liquid products and their injection into the internal mixer can be performed as part of the mixing cycle. This dosing and injection can be controlled by a PLC and may include pre-programming of operating information. For example, a cycle setting can be associated with the liquid products being fed into the mixer, including (but not limited to) their respective viscosities and dosing volumes, as well as the properties of the mixture exiting the mixer. For all modalities, a monitoring system could be established to ensure the correct dosage of the different liquid products in the internal mixer. Furthermore, this system could be implemented to guarantee the synchronization of the liquid product injection during the mixing cycle performed by the mixing system. At least part of the monitoring system could be provided on a portable device, such as a mobile network device (e.g., a cell phone, a laptop, network-connected wearable devices (including augmented and / or virtual reality devices, network-connected wearable devices, and / or any combination thereof). In some embodiments of the invention, the injector 10 (and / or the mixing system incorporating the injector 10) could receive voice commands or other audio data representing, for example, the start or stop of the delivery of a liquid product(s). The request could include a request for the current status of a mixing cycle, including (without limitation) the injection status of the liquid product(s). A generated response can be represented in an audible, visual, tactile (e.g., using a haptic interface), and / or virtual or augmented mode. In one configuration, the mixing cycle could include a training stage for injector 10 (or training of the mixing system incorporating injector 10) to recognize representative values ​​of the liquid products exiting the injector (e.g., temperature, viscosity, and volume) for comparison with target values. This stage could include training injector 10 to recognize discrepancies between the values ​​being compared. Each training stage includes a classification generated by a self-learning process. The injector 10 can inject several different liquid products without any mixing between them, thus avoiding the risk of cross-contamination. In this way, the injector 10 (and the mixing system incorporated within it) reduces the injection time of the liquid products into the mixer, resulting in a reduction in the mixing cycle time. Consequently, the invention preserves all the advantages of simultaneous injection without loss of flow. The terms "at least one" and "one or more" are used interchangeably. Intervals presented as "between a and b" include the values ​​a and b. While the specific features of the described device have been illustrated and described, it is understood that various changes, additions, and modifications could be made without departing from the spirit and scope of this description. Accordingly, no limitations should be imposed on the scope of the described invention except those stated in the appended claims. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

Having described the invention as above, the following claims are claimed as property:

1. An injector for introducing liquid products other than a rubber mixture into a chamber of an internal mixer in which the injector is mounted, characterized in that it comprises: a cylindrical housing of a predetermined length between an injection end and an opposite end of the injector, the housing comprising at least two injection channels, with each injection channel dedicated to the flow of a liquid product to form the mixture, each injection channel extending between an outlet of the injection channel, which is coextensive with the injection end of the housing and an opposite inlet, and each injection channel comprising a defined seat adjacent to the outlet;- a valve located in each injection conduit that measures a corresponding liquid product, the valve comprising a longitudinal stem extending between a rear portion located adjacent to the inlet of the injection conduit and a head located adjacent to the seat of the injection conduit; - a return spring located around the valve stem that controls the sliding movement of the valve relative to the injection conduit between a closed position, where the head engages with the seat and blocks the outlet of the injection conduit, and an open position, where the head no longer engages with the seat and unlocks the outlet of the injection conduit;an injection device integrated with the housing and comprising a supply conduit that supplies a liquid product to a corresponding injection conduit of a reservoir in which the liquid product is stored, each supply conduit being positioned perpendicular to a corresponding injection conduit to introduce the liquid product into the inlet of the injection conduit; and - a temperature control circuit within the injector.

2. The injector according to claim 1, characterized in that the temperature control circuit comprises: - at least two control channels extending axially along a portion of the housing length inside the injection device; at least one control conduit located in the injection device carrying a corresponding temperature control fluid to the injector, the control channels being connected to the control conduit; and a pipe in the injection device introducing the temperature control fluid into a corresponding control conduit from a temperature control fluid source.

3. The injector according to claim 2, characterized in that the housing comprises at least three injection conduits and the injection device comprises a supply conduit corresponding to each injection conduit.

4. The injector according to claim 3, characterized in that it comprises at least three control channels.

5. The injector according to any of claims 2-4, characterized in that the control ducts and pipes are connected in such a way that the temperature control fluid flows continuously in the temperature control circuit within the injector.

6. The mixing system for performing mixing cycles of a rubber mixture, characterized in that it comprises an injector in accordance with any of claims 1-5 and an internal mixer in which the injector is mounted.

7. The mixing cycle performed by the system according to claim 6, characterized in that it comprises the following stages: - an injection stage of the liquid products into the internal mixer through the injector, during which the liquid products are dosed according to the selected rubber blend recipe; - a temperature control stage comprising a stage of introducing one or more temperature control fluids into the temperature control circuit within the injector; and - a mixing stage, in the internal mixer, of the different liquid products injected by the injector and other raw materials to form the blend.

8. The mixing cycle according to claim 7, characterized in that the temperature control stage is performed before the liquid product injection stage.

9. The mixing cycle according to claim 7 or 8, characterized in that at least one of the liquid product injection stage and the temperature control stage is performed iteratively during the mixing cycle.

10. The mixing cycle according to any of claims 7-9, characterized in that the other raw materials introduced during the mixing stage comprise at least one elastomeric material.

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