Application of Square Steel Bar Rail in Crane Design

Application of Square Steel Bar Rail in Crane Design

European-style crane is a kind of medium-to-high-end bridge gantry crane. It is based on European lightweight and modular design concept and advanced manufacturing process, which makes the whole crane compact, stable, self-weight, height reduction, energy saving. It greatly reduces the users’ construction cost of the crane operating plant and crane operating costs and improves the overall quality and running performance of the crane. European cranes will become the mainstream of crane development and market demand. Basically, hot rolled square steel bar rails are used for 80% of European-style cranes and the square steel rails are incorperated into the calculation of strength and stiffness of the main beam.

There are three types of crane running tracks, namely crane rails, P-type rails and square steel bar. The top of the crane rail has a convex shape, and the bottom is a flat plate with a certain width to increase the contact surface with the foundation. The commonly used models are QU70, QU80, QU100, QU120, and the commonly used crane rail material is U71Mn steel. The cross section of the railway rail is I-shaped and has good bending strength. It is divided into two types, light rail and heavy rail.

Square steel can be regarded as a flat-top rail. It is generally used on cranes with small lifting capacity, slow running speed and infrequent work. The main material is  SS400 square steel and flat steel or S45C square steel bar and flat steel bar. The choice of rail is related to the size of the wheel and the width of the rail contact. Crane rails are generally used on cranes with large wheel diameters and heavy loads. Railroad tracks and square steels are suitable for wheel diameters from 200mm to 900mm, but their track characteristics are inconsistent.

Considering the the weight of the meter, square steel bar is not applicable. Since the general wheel rim is 20mm to 25mm, most manufacturers apply flat steel bar instead of square steel, that is, the height is reduced between 50mm and 70mm. Both the QU70 and P43 rails are constructed with a pressure plate and cannot be calculated with the main beam. The square steel can be welded to the main beam, and the calculation of the main beam section can include square steel. However, the square steel has a small moment of inertia and insufficient rigidity, and is not suitable for normal or semi-offset locations. European-style cranes are basically all off-track structures, and the square steel is subjected to the main web.

In summary, square steel bar used as a square steel track has the following characteristics.

1.The square steel is low in height and can reduce the effective space on the rail.

2.The contact area between the square steel and the wheel is increased to withstand the increased pressure.

3.Square steel (flat steel) is relatively light in weight and easy to reduce the weight of the whole machine.

4.The square steel is welded to the main beam and can be calculated in the main beam section.