Design of rail connection bolts

- Oct 16, 2019-

Design of rail connection bolts

The guide rails are precision mechanical products. Its length and diameter are relatively large. It is not only a high-precision part, but also an elongated flexible shaft part. This requires precision grinding of the guide rails in accordance with the specified torque, torque and torsion conditions during machining.


In the design of the rail connecting bolts, the bolts on the machine frame need to be tightened with the same tightening torque during the machining to ensure the accuracy. If the bolt strength grade and torsion torque are selected improperly during processing or installation, it will directly affect the working accuracy of the guide rail. When subjected to vibration and shock, the guide rail may also be biased. Correct selection of the bolt strength and rated torque of the guide rail is a prerequisite for ensuring the processing and use of the precision guide rail and preventing the deviation of the guide rail.


In addition, if the guide rail is subjected to vibration and shock, the guide rail and the slider may deviate from the original position, and generally can be fixed by screws, baffles, and positioning pins according to different situations. In the case of low precision requirements, the number of bolts used to mount the rails can be reduced, and the remaining holes can be used as holes for the locating pins. To prevent the guide rail from moving, when installing the guide rail on the machine seat, use a wrench to tighten the guide rail with a certain tightening torque. Calculate the bolt tightening force per unit length or rail area:


(1) When the guide rail is a rigid body, the total tension axial force is divided by the total length of the guide rail or all the reference area values.

(2) When the guide rail is used as an elastic body, it is the total tightening axial force of the bolt within the deformation range of the guide rail itself, divided by the length of the deformed portion or the base area. It is suitable to calculate the tightening axial force per unit length, and when the tension per unit length is increased, the sliding load of the guide rail is also increased.


The guide rail has long service life, high mechanical stability and high pressure resistance, and is widely used in the machinery industry.