Aplicaciones
Application Notes
Thickness Testing of Reinforced Rubber Conveyor Belts
 Application: Measuring the depth of textile and steel reinforcements in rubber conveyor belts, and measuring the remaining rubber thickness of in-service belts.
Background: A wide variety of rubber conveyor belts for heavy-duty industrial and mining service such as ore and mineral transportation incorporate internal layers of woven fabric or steel cords for strength reinforcement. Conveyor belt manufacturers need to check the depth of the reinforcement layer across the belt in order to insure that the product meets specification. After installation, belt users need to periodically check the thickness of the remaining rubber as the belt wears down in order to estimate the remaining service life before replacement. Because large belts can be very expensive, accurate information on remaining rubber thickness is valuable to users. Our instruments and transducers have been successfully employed in this test for many years. Sound energy reflects off the first layer of reinforcement, and in the case of textile or fabric reinforced belts very little sound energy will penetrate deeper. Measurement of total belt thickness is normally possible only in the case of some steel-reinforced belts where there is sufficiently wide separation between the steel cords to permit sound energy to travel unobstructed the opposite side of the belt. However, the critical dimension for most users is the amount of rubber over the first reinforcement layer, not total thickness. This is usually a straightforward application for ultrasonic thickness gaging. Equipment: Rubber thicknesses under approximately 20 mm or 0.750 in. can usually be measured with thickness gage models 35, 35DL, and 38DL PLUS. For greater thicknesses, the high penetration version of these gages (models 35HP, 35DLHP, and 38DL PLUS with high penetration transducer option) should be used. Thickness measurements can also be made with any of the Epoch series flaw detectors. In the case of certain very large belts, with rubber thicknesses approaching 50 mm or 2 in., the Epoch 4 is the preferred instrument. The transducer selection will depend on the range of rubber thickness to be measured. For rubber layers between approximately 1 mm (0.040 in.) and 6.25 mm (0.250 in.), a 2.25 MHz delay line transducer (M207-RB) will usually be recommended. For measurement of rubber between approximately 2.5 mm (0.100 in.) and 25 mm (1 in.), a 2.25 MHz high penetration contact transducer (M1036) is commonly used. Other transducers are available for thinner and thicker rubber layers. As with any application involving attenuating materials, use of gel couplant or glycerin (Couplant B) is recommended in preference to less viscous fluids. In the case of severely worn in-service belts, any loose rubber or other debris should be removed from the surface before testing. Procedure: In the most common situation, using the M1036 transducer to measure the outer rubber layers on belts with textile or fabric reinforcement, start with the gage's M1036 default setup and increase maximum gain as necessary to measure the thickness range of interest. If necessary for measurement of thin belts, increase initial gain as well. In any of these setups, gain may usually be increased up to the point where the gage displays a constant false reading when the transducer is uncoupled, which indicates that gain is too high.  Typical conveyor belt measurement with M1036
To measure thin rubber layers over textile or fabric reinforcement with the M207 delay line transducer, use the M207 Mode 2 default setup and adjust gain and blanking as necessary based on the echoes from a reference standard.
Measurement of depth of braided steel cord reinforcements can be more challenging because their irregular contour presents a less optimum reflecting surface. Careful adjustment of instrument gain with the aid of a reference sample is recommended. Also note that echo polarity will be positive rather than negative because the steel represents a high impedance reflector.
Sound velocity in rubber compounds will typically be on the order of 1.650 mm/uS or 0.0650 in/uS. The Olympus NDT Applications Lab is always available to assist with gage setups for specific transducers and belt types. |
Products used for this application
35
El modelo 35 de bolsillo es un medidor de espesor por ultrasonidos portátil para realizar mediciones precisas sobre metal, plástico, caucho, vidrio y compuestos, utilizando palpadores de un elemento. Permite medir una amplia gama de espesores, de 0,08 mm a 635,0 mm. Cuenta con las funciones opcionales Forma de onda en tiempo real (Live Waveform) y Modo de ajuste (Adjust Mode).35DL
El modelo 35DL de bolsillo es un medidor de espesor por ultrasonidos portátil para realizar mediciones precisas sobre metal, plástico, caucho, vidrio y materiales compuestos, utilizando palpadores de un elemento. Tiene las mismas características que el modelo 35, pero incluye un registrador de datos interno.35DL-HP
El modelo 35DL-HP de bolsillo (alta penetración) es un medidor de espesor por ultrasonidos portátil para realizar mediciones en materiales espesos o con gran atenuación del sonido, como fibra de vidrio, fundición y caucho, utilizando palpadores de un elemento. Tiene las mismas características que el modelo 35, pero incluye un registrador de datos interno.38DL PLUS
El 38DL PLUS es un medidor de espesor por ultrasonidos de avanzada. Utiliza un palpador dual para la inspección de superficies internas corroídas e incluye las funciones THRU-COAT y eco a eco. También utiliza palpadores de un elemento para medir con precisión los espesores de materiales finos, muy espesos o de múltiples capas.EPOCH 1000 Series
El EPOCH 1000 es un detector de defectos por ultrasonidos convencional de avanzada al que se puede optimizar adicionando la creación de imágenes phased array en un centro de servicio autorizado de Olympus. Sus características claves son: la conformidad a norma EN12668-1, un juego de 37 filtros digitales en el receptor y una frecuencia de repetición de impulsos de 6 kHz para la inspección a alta velocidad.EPOCH 600NEW
El EPOCH 600 es un detector de defectos por ultrasonidos portátil de nivel intermedio. Su peso es de solamente 1,68 kg y su caja horizontal está construida para resistir a las exigencias de entornos extremadamente rigurosos. Responde a la norma EN12668-1 e incluye funciones como un emisor de ondas cuadradas ajustable de 400 V con tecnología PerfectSquare y el filtrado digital que mejora la relación señal-ruido.EPOCH LT
El EPOCH LT es un detector de defectos digital de base, portátil, de 38 mm de espesor, alojado en una caja vertical de 1 kg de peso, que ofrece una frecuencia de actualización de pantalla rápida de 60 Hz como mínimo, la calibración automatizada del palpador, un registrador de datos digital y muchas otras funciones de medición.EPOCH LTC
El EPOCH LTC es un detector de defectos por ultrasonidos portátil de nivel intermedio, de 0,96 kg de peso, alojado en una caja vertical compacta. Es un instrumento con todas las funcionalidades, conforme a la norma EN12668-1 y que ofrece una amplia variedad de características de serie y específicas en opción, para responder a sus necesidades de inspección.EPOCH XT
El EPOCH XT es un detector de defectos por ultrasonidos portátil de avanzada, que cuenta con numerosas funciones estándares de medición, incluyendo un emisor de ondas cuadradas ajustable, filtros digitales de banda estrecha y de banda ancha seleccionables, una gama de ganancias de 0 a 110 dB, las funciones de memoria y de mantenimiento de picos y una frecuencia de repetición de impulsos (PRF) ajustable.Inspection & Measurement Systems
