Due to the anisotropy and special production process of the carbon fiber composite material itself, the matrix after molding should not be machined, otherwise the continuity of the matrix fiber will be damaged and the mechanical properties will be affected. In order to ensure the installation accuracy and performance requirements of carbon fiber composite materials, metal structural parts are usually placed on the carbon fiber composite material matrix in advance, and the precision of the components is guaranteed by processing the embedded parts.
Most of the embedded parts are made of titanium alloy materials, which have good specific strength and specific stiffness values. The types of embedded parts can be divided into surface contact embedded parts, pin embedded parts, screw embedded parts, etc. according to different functions.
(1) Surface contact embedded parts
Due to the poor processing performance of the fiber, the flatness of the 100mm×100mm area is only about 0.1mm, and the surface quality and dimensional tolerance cannot be well guaranteed. The direct processing of the fiber matrix generally cannot meet the requirements. This problem can be well solved by adding embedded parts during the production of the fiber matrix, and after molding, the embedded parts are finished to ensure proper positioning size and shape and position tolerance values.
(2) Pin embedded parts
The screw connection can only be tightened but not positioned. When precise positioning is required, a pin must be used to ensure it. The structural design of the embedded part of the pin and the embedded part of the thread is similar, and it is also necessary to prevent the embedded part from rotating and moving in the axial direction. In order to ensure the correct fit between the pin and the pin hole, the pin hole is generally processed after the embedded part is bonded to the fiber matrix.
(3) Screw embedded parts
Carbon fiber composite materials are unidirectional materials. The strength of the threaded holes directly processed on the fiber matrix is very low, and the thread teeth are easily damaged. For components that require screw fastening, screw embedded parts are necessary. The threads of screw embedded parts are generally pre-processed and then glued into the fiber matrix. In order to prevent radial rotation and axial play of the embedded parts during screw tightening, knurling can be made on the outer diameter to increase the bonding strength if necessary.
The shape of the embedded parts is determined by the different shapes of the fiber matrix and the different use occasions. By adopting measures such as knurling and positioning pins on the outer diameter of the square head flange, the embedded parts can generally be ensured that no displacement occurs in the matrix.
