Estudio para el mejoramiento de la resistencia al desgaste de los martillos desmenuzadores de los molinos de los centrales azucareros utilizando el electrodo UTP 711-B
Fecha
2019
Autores
Cárdenas Márquez, Jaime Ibrahin
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Editor
Universidad Central ‘‘Marta Abreu’’ de Las Villas. Facultad de Ingeniería Mecánica e Industrial. Departamento de Ingeniería Mecánica
Resumen
En el trabajo se dan a conocer las particularidades del funcionamiento de los molinos utilizados en la preparación de la caña y en particular los mecanismos de desgaste presente en los martillos desmenuzadores. En este caso por las condiciones de los suelos y de cultivo en Cuba, el desgaste abrasivo es el predominante. Asimismo se realiza una búsqueda en la literatura para conocer la composición química, microestructura, y dureza de depósitos de recargue, empleados de los consumibles recomendados por la industria azucarera para el blindaje de los martillos de los molinos desmenuzadores. De acuerdo a la revisión se determinó que en nuestro país, el electrodo empleado es el UTP 711-B, recomendado para piezas sometidas al desgaste abrasivo. En el trabajo se determinó que con el aumento de la temperatura en la superficie de los martillos durante el proceso de recargue aumenta considerablemente el coeficiente de dilución. Este fenómeno provoca que en el depósito no se obtenga una aleación con contenidos de C y Cr, cercanos a la que aporta el consumible y por lo tanto, la microestructura predominante sea la austenita y una red eutéctica interdendrítica. Debido a que en la microestructura, la zona eutéctica ocupa un área relativamente baja, el depósito alcanza solo una dureza de 525 HV, por debajo de la indicada para el consumible que es de 650 HV. Este resultado hace que la resistencia al desgaste abrasivo sea baja, causa fundamental del deterioro prematuro de los martillos desmenuzadores, al aplicar el procedimiento actual empleado en el recargue.
In the work the particularities of the operation of the mills used in the preparation of the cane and in particular the wear mechanisms present in the shredder hammers are made known. In this case, due to soil and crop conditions in Cuba, abrasive wear is predominant. Likewise, a search is made in the literature to know the chemical composition, microstructure, and hardness of recharge deposits, employees of the consumables recommended by the sugar industry for the shielding of the hammers of the crushing mills. According to the review it was determined that in our country, the electrode used is UTP 711-B, recommended for parts subject to abrasive wear. In the work it was determined that with the increase of the temperature on the surface of the hammers during the recharge process the dilution coefficient increases considerably. This phenomenon causes that the deposit does not obtain an alloy with contents of C and Cr, close to the one that contributes the consumable and therefore, the predominant microstructure is austenite and an interdendritic eutectic network. Because in the microstructure, the eutectic zone occupies a relatively low area, the deposit reaches only a hardness of 525 HV, below that indicated for the consumable which is 650 HV. This result means that the abrasive wear resistance is low, a fundamental cause of the premature deterioration of the shredder hammers, when applying the current procedure used in the recharge.
In the work the particularities of the operation of the mills used in the preparation of the cane and in particular the wear mechanisms present in the shredder hammers are made known. In this case, due to soil and crop conditions in Cuba, abrasive wear is predominant. Likewise, a search is made in the literature to know the chemical composition, microstructure, and hardness of recharge deposits, employees of the consumables recommended by the sugar industry for the shielding of the hammers of the crushing mills. According to the review it was determined that in our country, the electrode used is UTP 711-B, recommended for parts subject to abrasive wear. In the work it was determined that with the increase of the temperature on the surface of the hammers during the recharge process the dilution coefficient increases considerably. This phenomenon causes that the deposit does not obtain an alloy with contents of C and Cr, close to the one that contributes the consumable and therefore, the predominant microstructure is austenite and an interdendritic eutectic network. Because in the microstructure, the eutectic zone occupies a relatively low area, the deposit reaches only a hardness of 525 HV, below that indicated for the consumable which is 650 HV. This result means that the abrasive wear resistance is low, a fundamental cause of the premature deterioration of the shredder hammers, when applying the current procedure used in the recharge.
Descripción
Palabras clave
Centro de Investigaciones de Soldadura, Electrodo UTP 711-B, Metalografía