METHOD FOR DETERMINING THE TEMPERATURE OF A RUBBERY MATERIAL ENTERING INTO THE COMPOSITION OF A TIRE

Abstract

The method includes the step of positioning the product to be measured on a transport table. The method proceeds with the step of advancing the product under a frame that includes at least one terahertz sensor. The method continues with the step of emitting incident terahertz radiation in the direction of the product. The method proceeds with the step of detecting the signal corresponding to a multiple spectrum of terahertz rays reflected by the interfaces encountered by the incident ray. The method continues with the step of analyzing the signal to determine various peaks corresponding to the various interfaces encountered. The method proceeds with the step of determining, on the basis of the amplitude of each peak, the temperature of each layer of material through which the incident ray passes.

Claims

1. A method for determining the temperature of at least one layer of a multilayer polymer product, the method comprising the following steps: positioning the product to be measured on a transport table, advancing the product under a frame comprising at least one terahertz sensor, emitting incident terahertz radiation in the direction of the product, detecting the signal corresponding to a series of pulses reflected by the interfaces encountered by the incident ray, analyzing the signal to determine various peaks corresponding to the various interfaces encountered, and determining, on the basis of the amplitude of each peak, the temperature of each layer of material through which the incident ray passes.

2. The method according to claim 1, wherein the multilayer polymer product is a product made up of several layers of rubber material, before or after curing.

3. The method according to claim 2, wherein the product is a tire, a caterpillar track or a conveyor belt.

4. The method according to claim 1, comprising a step of processing the raw signal before the analysis step.

5. The method according to claim 1, wherein the speed at which the product advances is between 0 and 70 meters per minute.

6. The method according to claim 1, wherein the acquisition rate of the terahertz sensor is greater than 100 Hz.

7. The method according to claim 1, and further comprising a step of determining, as a function of the difference between two peaks of the signal, the thickness of each layer of material through which the incident ray passes.

8. A system for determining the characteristics of at least one layer of a multilayer polymer product, comprising: a support table for advancing a multilayer polymer product, a terahertz sensor, a means for acquisition and analysis of a signal reflected by the polymer product, and a means for implementing a method for determining the temperature of a layer of the multilayer material according to the method of claim 1.

9. The system according to claim 8, further comprising a means configured to determine a thickness of each layer of material through which the incident ray passes as a function of a difference between two peaks of the signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Further advantages and embodiments of the present disclosure will emerge from the description, which is non-limiting, of the various illustrative figures, in which:

[0047] FIG. 1 shows a system for implementing a method according to the disclosure,

[0048] FIG. 2 schematically shows the impact of terahertz radiation on a multilayer product,

[0049] FIG. 3 shows the raw and processed signal resulting from acquisition by a terahertz sensor implemented in the disclosure.

DESCRIPTION OF EMBODIMENTS

[0050] In an example of an embodiment of a method according to the disclosure, illustrated in FIG. 1, a multilayer product 101 is positioned on a support table 102. This table is provided with means allowing the product to advance in the direction X. The table is surmounted by a frame on which is arranged a terahertz sensor 103. The speed of advance of the product is set according to the acquisition speed of the terahertz sensor. It is preferably between 10 and 70 meters per minute.

[0051] FIG. 2 schematically shows a product 1 comprising two layers 11 and 12 respectively forming media having different refractive indices, n1 and n2. This product 1 is placed on a support 102 (corresponding to the table 102 in the previous figure) having a refractive index which is different again, and the upper surface of the layer 11 is in contact with the ambient air 13.

[0052] When the terahertz sensor emits radiation, an incident THz ray reaches the product 1. This product in fact has three interfaces: an interface between the air and the layer 11, an interface between the layer 11 and the layer 12, and an interface between the layer 12 and the support 102.

[0053] When the incident THz pulse 14 passes through an interface, a fraction of the pulse is reflected. Thus, when the THz pulse propagates in the multilayer product, a series of pulses 15 is reflected.

[0054] FIG. 3 shows the shape of the signal representing a series of pulses acquired on a product comprising two layers of rubber material.

[0055] The top curve shows the raw signal, and the bottom curve shows the signal after pre-processing, which is carried out to aid analysis.

[0056] It is known that the delay between two consecutive pulses is directly proportional to the thickness of material passed through. The calculation of the thickness of a layer on the basis of the delay between two consecutive pulses is performed using the real part of the refractive index. This number, which is characteristic of the material making up the layer, represents the speed of propagation of the THz pulse therein. Thus, on the processed signal shown in FIG. 3, the thickness of the layer 11 is determined by measuring the time lag between peak 1 and peak 2, and the thickness of the layer 12 is determined by measuring the time lag between peak 2 and peak 3.