Design and application of guide mechanism for linear bearings in composite material production

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Design and application of guide mechanism for linear bearings in composite material production

The application of composite materials in the aerospace field is becoming increasingly widespread, which puts forward higher requirements for the forming and processing technology of composite materials. Especially, the precision of process parameter control in forming technology directly affects the quality of its products. Among them, the precision of pressure control in composite material tape winding forming is one of the key factors affecting the quality of wrapped products. The precision and stability of pressure control depend not only on the control algorithm, but also on the precision and stability of the pressure application guiding mechanism, namely the linear bearing and linear rolling guide.

The main factors that affect the accuracy and stability of pressure transmission by the guiding mechanism include the performance of the transmission element, the friction force of the joint surface, and the installation accuracy. At present, linear bearings and linear rolling guide rails are mainly used as transmission components for composite material tape winding pressure application guidance mechanisms.

Linear bearings are a low-cost linear motion mechanism with low transmission friction resistance, high accuracy, and fast movement. However, due to the point contact between the load bearing ball and the quenched transmission shaft, the allowable load is small, and larger impact loads can damage the ball, resulting in a significant increase in the friction coefficient at the contact surface.

Linear bearings have poor ability to withstand bending moments. In addition, they are subjected to overturning moments under actual winding conditions, resulting in elastic deformation and uneven force distribution of the load ball. Load balls with larger elastic deformation are more prone to wear and damage when subjected to impact force, which will have a greater impact on the application of winding pressure. The linear rolling guide rail has simple lubrication, low friction resistance, high positioning accuracy, large bearing capacity, good stiffness, and can withstand forces and overturning moments in four directions. Moreover, the linear rolling guide rail can improve the stiffness of the joint surface by pre loading, and the load bearing balls are not easily worn and damaged.

The main forces acting on the pressure guiding mechanism based on linear bearings are:

The thrust F1 of the cylinder, the pressure Fn of the mold tire on the hot pressing roller, the force F2 applied by the connector on the transmission shaft, the support force T of the linear bearing sleeve on the transmission shaft, the friction force f1 of the linear bearing joint surface, and the tangential force f of the mold tire on the hot pressing roller τ， The self weight of the hot pressing roller is g1, and the self weight of the transmission shaft is g2. The transmission shaft also bears the force of f τ、 The overturning moment M generated by g1, g2, T, and F2 (as shown in Figure 1).

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