Online surfacing welding repair method for large vertical mill grinding roller

Abstract

The invention belongs to the technical field of surfacing welding methods, in particular to an online surfacing welding repair method for a large vertical mill grinding roller. Compared with the priorart, the invention provides continuous, long-time heating effects for the large vertical mill grinding roller by the use of pre-heating air and cooling air and effectively solves the various problemsin the existing online surfacing welding repair. The weld bead is closely connected with the outer surface of the large vertical mill grinding roller to be repaired and does not fall off easily. In addition, the weld bead has no crack and is resistant to wear, which conforms to the repair requirements.

Description

technical field [0001] The invention belongs to the technical field of surfacing welding methods, and particularly relates to an on-line surfacing welding repair method for a large vertical grinding roller. Background technique [0002] During the operation of the large vertical grinding roller (hereinafter referred to as the grinding roller), the outer surface of the roller will inevitably be worn out due to the long-term extrusion of the material and the grinding disc. As the amount of wear increases, the output of the mill continues to decline until it needs to be stopped for maintenance. Grinding rollers with poor or unusable results can be repaired by surfacing welding. Since the grinding rollers are generally made of materials with high hardness and high wear resistance, they are not only expensive, but also need to be returned to the factory for repair and replacement. Complex, long cycle, high cost. [0003] In order to solve the above problems, the grinding roller...

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Problems solved by technology

[0004] However, in practice, there are many problems affecting the quality, safety and progress of surfacing welding that are easily overlooked, resulting in substandard surfacing welding quality, affected progress, many safety hazards, and affecting safe production and maintenance costs.

[0005] For example, the grinding roller has a relatively large size and thickness. When the traditional surfacing method is used for online repair, the welding part of the grinding roller cannot be preheated to a suitable temperature before the surfacing point, such as the Chinese patent with the publication number CN101433990B It discloses a method of covering the entire workpiece as a whole by covering the track heater and then preheating the track heater. The track heater can only preheat the grinding roller between the surfacing and repairing of the grinding roller, and the temperature of the grinding roller can only be determined by the position For a period of time, especially on the inner surface of the grinding roller, the temperature drops very quickly, which cannot guarantee the overall and continuous heating effect during the surfacing of the grinding roller, which leads to low strength or even failure of the connection between the weld bead and the grinding roller, and the surfacing The weld bead formed by welding is easy to fall off, the weld bead has cracks, and the weld bead is not wear-resistant. Phenomena occur from time to time. In the slightest, rework occurs, and in severe cases, the surfacing part is broken, affecting the repair progress, and increasing the repair cost.

[0006] The working place of the mill is generally open, and the air has a great influence on the temperature of the grinding roller, which makes it difficult for the patented preheating method to be applied to the online repair work of the grinding roller

For example, due to the long repairing time of the grinding roller, during the continuous repairing process, the welding points continue to heat the outer surface of the grinding roller, resulting in the continuous increase of the temperature of the outer surface, and the inner and outer surfaces of the grinding roller are formed. A large temperature difference can easily cause radial cracks or even bursting of the grinding roller; for example, when the air temperature is low, the weld bead welded by the grinding roller is subjected to sudden cooling, and the weld bead is prone to warping, fracture, embrittlement and other defects. As a result, the connection strength between the weld bead and the grinding roller, and between the weld bead and the weld bead becomes low, and the surfacing repair effect is not good or even impossible to complete

[0007] The existing on-line repair method for grinding rollers has defects such as long surfacing time, poor welding bead connection stability, and inapplicability to continuous and long-term surfacing repair work, making online repairing of grinding rollers only for some Can be used under certain circumstances, but cannot be promoted

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