With the development of railway transportation to high speed and heavy load, the requirements for the quality of rails are getting higher and higher. As the speed increases, the rail track life becomes shorter and shorter. Because the traditional process has inherent defects: asymmetry in geometric dimensions, rail height, bottom low and wide tolerance, etc. Surface scratches, decarburization, etc., appearance flatness and blind spots in internal quality inspection. All seriously hinder the improvement of rail quality.
The rail track produced by the traditional die casting process can no longer meet the requirements of the high-speed railway for the dimensional accuracy, internal quality and mechanical properties of the rails.
In order to meet the requirements of performance and life, the current production method of rails has gradually adopted forging or rolling instead of casting.
Typically, rails (or rail track) used in railways are formed by heating billets (or billets) and hot rolling them into a specific shape, and then, after heat treatment according to the desired mechanical properties, they are cooled to room temperature. Then, after rectification, certain inspections can be carried out and the rail becomes a finished product. The heat treatment is performed as necessary, and there are cases where these operations are omitted.
The hot rolling process is usually carried out with the rails lying transversely. Without heat treatment, the rails are transported with their sides to a cooling bed (or cooling bed), where they are cooled.
However, since the cross-sectional shape of the rail is asymmetric in the horizontal direction when in the upright state, during the cooling process after hot rolling, a curvature is generated in the height direction (here, we refer to as the height direction when the rail is in the upright state). curvature in the horizontal direction due to curvature in the direction, and curvature in the transverse direction due to curvature in the width direction). In conventional operating methods, due to the possible increase in bending in the height direction and the tendency of the rail to become unbalanced and toppled, this results in the normal transport of the rail, placement of the rail in the cooling bed, and withdrawal of the rail from the cooling bed Difficulties. Therefore, from the viewpoint of preventing such an unbalanced state as much as possible, in most of the above-mentioned manufacturing processes, the rails are handled and conveyed sideways. However, when the rail is rapidly cooled by air or water mist, this cooling operation is performed while the rail is in the upright state, but as described in Japanese Unexamined Patent Application Publication S62-13528, the heat treatment is usually performed while the rail is in the upright state proceed, and thus, the rails are arranged laterally until they reach the cooling bed.
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