Temperature management of rubber mixtures discharged from a converging conical twin-screw mixer

Patent metadata

Field	Value
Publication number	US-12515374-B2
Application number	US-202017436351-A
Country	US
Kind code	B2
Filing date	Feb 25, 2020
Priority date	Mar 6, 2019
Publication date	Jan 6, 2026
Grant date	Jan 6, 2026

Abstract

A mixing and cooling system ( 1 ) includes a mixing and screw-extrusion machine ( 10 ) with a mixer ( 12 ) having a converging conical twin screw; a ram ( 30 ) that moves along the inside of an introduction hopper ( 24 ) of the machine; a roller nose system disposed just downstream of an outlet ( 25 ) of the mixer to form a sheet ( 112 ) of the mixture exiting the mixer; and a mobile sleeve or sleeves ( 34 ) that move in a linear movement relative to the outlet. The system also includes a cooling system with a spray installation(s) ( 102, 104 ) that delivers water at a predetermined rate to the sheet exiting the machine; a suction installation(s) proportionate to each spray installation; and at least one transport means ( 114, 116 ) that transports the sheet in a predetermined direction.

First claim

The invention claimed is:

1 . A mixing and cooling system that performs a mixing cycle and manages temperatures of a rubber mixture, the mixing and cooling system comprising:
a screw mixing and extrusion machine including:
an introduction hopper having an inside;
a mixer, the mixer being a converging conical twin-screw mixer having:
sleeves in which two screws are mounted at an angle between an opening and an outlet, the opening being disposed upstream of the sleeves and connected to the introduction hopper for the introduction hopper to feed the two screws, the outlet being disposed downstream of the sleeves to discharge the rubber mixture at an end of a mixing process of the mixing cycle;
one or more motors coupled to the two screws to rotate the two screws in the sleeves during the mixing process;
one or more movable doors provided at the outlet and movable to allow, during the mixing process, the discharge and shaping of the rubber mixture; and
one or more mobile sleeves that are arranged top-down towards the outlet and includes a surface that defines a mixing space between the surface and the two screws, the mobile sleeves linearly movable with respect to the outlet to adjust the mixing space between the sleeves and the two screws; and

a ram with an inner surface having a shape that is complementary to an outer contour of the two screws, the ram moving along the inside of the introduction hopper;
a roller nose system including two counter-rotating rollers arranged just downstream of the outlet, the two counter-rotating rollers being positioned to oppose each other and form a sheet of the rubber mixture as the rubber mixture is discharged from the mixer; and
a cooling system including:
at least one spray station that delivers water at a predetermined water flow rate to the sheet of the rubber mixture exiting the screw mixing and extrusion machine;
a suction station corresponding to each spray station that suctions air at a predetermined air flow rate; and
at least one transport means that transports the sheet of the rubber mixture in a predetermined direction corresponding to a cooling process realized by the cooling system.

2 . The mixing and cooling system of claim 1 , wherein each spray station includes one or more spray booms positioned at a respective spray station, each boom being in communication with a water and air supply source that supplies water and air to one or more nozzles at a predetermined water flow and air pressure.

3 . The mixing and cooling system of claim 1 , wherein each spray station includes one or more nozzles configured to spray the water to produce atomized air droplets, and
wherein the cooling system also includes:
a detection system including one or more sensors configured to detect, throughout the mixing cycle and the cooling process, an actual water flow, an actual air intake flow, and the presence at the correct pressure of the atomized air droplets in order to generate one or more corresponding signals; and
a monitoring system include at least one programmable controller communicatively coupled to the detection system and configured to perform at least one of the following operations: prediction, comparison, and adjustment based upon the signals received from the detection system.

4 . The mixing and cooling system of claim 1 , wherein the one or more movable doors comprise sliding shutters installed with respect to the outlet so that the sliding shutters move linearly between a closed position, in which the sliding shutters prevent the rubber mixture from exiting the mixer, and an open position, in which the sliding shutters prevent the rubber mixture from escaping through the sides of the two counter-rotating rollers to force the rubber mixture to pass between the counter-rotating two rollers and to form the sheet of the rubber mixture with a predefined thickness and width.

5 . The mixing and cooling system of claim 1 , wherein the two screws are mounted in the mixer so that each screw thread tangentially contacts a surface of the opposite screw so that the two screws remain substantially in contact with each other when rotating the two screws at an angle and at a center distance that facilitates self-cleaning.

6 . The mixing and cooling system of claim 5 , wherein the two screws have an interpenetrated profile, a conjugate profile, or both.

7 . The mixing and cooling system of claim 1 , wherein the sleeves include cooling channels that manage the temperature of the rubber mixture during the mixing cycle.

8 . A mixing and cooling process that includes a mixing cycle performed using the mixing and cooling system of claim 1 , wherein the mixing cycle comprises at least one mixing process performed by the screw mixing and extrusion machine, and the mixing process includes the following steps:
a step of rotating the two screws in a forward direction with the one or more movable doors closed; a step of introducing the rubber mixture into the screw mixing and extrusion machine, during which the two screws continue to rotate and the one or more movable doors remain closed; a step of mixing a rubber mixture in the screw mixing and extrusion machine; a step of emptying the screw mixing and extrusion machine, during which the one or more movable doors open to discharge the rubber mixture from the outlet and during which the two screws continue to rotate until the mixer is empty; and a step of shaping rubber mixture discharged from the mixer in the form of the sheet in order to deliver the rubber mixture toward a downstream process.

9 . The mixing and cooling process of claim 8 , in which the step of introducing the rubber mixture includes introducing raw materials to form the rubber mixture.

10 . The mixing and cooling process of claim 8 , in which the step of introducing the rubber mixture includes introducing one or more masterbatches.

11 . The mixing and cooling process of claim 8 , further comprising at least one cooling process carried out by the cooling system of the mixing and cooling system after the step of shaping rubber mixture discharged from the mixer, the cooling process including the following steps:
a step of circulating the sheet exiting the screw mixing and extrusion machine in a treatment direction at the level of at least one spray station; a step of spraying the sheet in the vicinity of the spray station during the circulation of the sheet; and a step of evacuating air containing evaporated water.

12 . The mixing and cooling process of claim 11 , in which the cooling process further includes the following steps:
a step of detecting a water flow rate attained at an elapsed time during the cooling process; a step of using the detected flow to predict temperature and added water values for the rubber mixture at the end of the current cooling cycle; a step of comparing target and predicted values; a step of adjusting the actual water flow rate so that properties of the mixture attain desired properties for the mixture; and a step of evacuating the sheet from the cooling system when the properties of the mixture attain the desired properties for the mixture.

13 . The mixing and cooling process of claim 8 , wherein the mixing process further includes a step of reintroducing rubber mixture into the mixer, during which the rubber mixture discharged from the mixer returns to the mixer through the introduction hopper.

14 . The mixing and cooling process of claim 13 , wherein the mixing process and the cooling process are executed simultaneously.

15 . The mixing and cooling process of claim 8 , wherein:
the one

Assignees

• Michelin & Cie

Inventors

• Dussardier Bruno
• Tournebize Aurelien
• Ablonet Thierry
• Huc Laurent
• Egerszegi Christophe

Classifications

• B29B7/823

  Temperature control · CPC title

• B29B7/582

  for discharging, e.g. doors · CPC title

• B29B7/489

  Screws (B29B7/482 takes precedence) · CPC title

• B29B7/484

  with two shafts provided with screws, e.g. one screw being shorter than the other (B29B7/482 takes precedence) · CPC title

• B29C48/405

  Intermeshing co-rotating screws · CPC title