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Selection and calculation of the spacing between elevator guide rails

7/27/2020 6:41:59 PM

 The force analysis of the car shows that the gravity generated by the car and its accessories and the pulling force of the car acting on the traction rope are not a pair of force and reaction force. Although the car runs on linear guide rails, due to the manufacturing and installation errors of the guide rails, absolute plumb weight cannot be achieved, and the car running in the hoistway will be affected by various airflows. In addition, due to the different geometric shapes and suspension modes of the car, the load will fluctuate in the car, and the load capacity and the pulling force on the traction rope cannot always be maintained in the plumb direction. The car will produce component forces in the horizontal direction. This horizontal component force is defined as the supporting reaction force. The supporting reaction force acts on the guide shoe through the guide rail, and then is transmitted to the car. The reaction force of the supporting reaction force on the guide shoe will cause the bending effect of the guide rail. The three important factors that affect the reaction force are: the suspension mode of the car and the balance weight; the position of the car and the balance weight on the guide rail; the uniformity of the load distribution in the car. Considering the force, when calculating the bending stress of the guide rail, in order to simplify the calculation, the following assumptions can be made: the guide rail is regarded as a continuous beam with flexible support; the combined force point is between two adjacent brackets, and the maximum bending moment acts on the rail transverse Neutral layer of cross section.

For low-speed and light-load elevators, only the geometric parameters of the guide rails need to be determined according to the bending stress. However, when the safety device acts on the guide rail, the combined effect of bending stress and compressive stress must be considered to determine the size of the guide rail. The bending stress is proportional to the distance between the guide rails, and the distance between the guide rails is inversely proportional to the modulus of the bending section. Therefore, the bending stress of the guide rail increases as the distance between the guide rail brackets increases. The spacing between the brackets cannot be too large. The modulus of the curved section W is determined by the material and model of the guide rail. Appropriately increasing W is also a way to increase the distance between brackets. If the role of safety devices is considered, the combined effect of bending stress and compressive stress must be considered at the same time.

There are two methods to obtain the impact load coefficient: the national standard method and the formula derivation method. Check the national standard for guide rails with low tensile strength: formula derivation Fac is used for tensile strength >370MPa,

To determine or check whether the guide rail selection is successful, its judgment method is: It can be seen that if the most commonly used guide rail with a tensile strength of 520MPa is selected, the allowable stress of the guide rail will not exceed 290MPa under the operation of the safety gear.

In short, in the design and installation of the elevator, the basic parameters of the elevator should be determined according to the actual situation, and the comprehensive analysis of various factors should be done. The selection of the guide rail and the measurement of the distance between the guide brackets should be done correctly. This not only ensures the quality of the elevator guide rails, but also reduces the construction and installation costs, and improves the safety performance of the elevator after it is put into use. The comprehensive stress of the guide rail increases with the increase of the distance between the supports. However, the excessive number of railway supports will lead to an increase in construction costs. It is usually selected in a backward way. According to the maximum bracket spacing, the corresponding maximum comprehensive stress is first calculated, and when the requirements of national standards are met, the selection can be used safely and can reduce production costs and installation guidelines. This is an optimization During the actual installation of the guide rail, the guide rail support spacing is greater than 2.5 cm can also be designed, but the material and cross-sectional shape of the guide rail must be improved, and the bending strength of the guide rail must be checked.