Diagram of Fixture for Vibration Drilling of Holes in Composite Materials

Abstract

This paper discusses the use of vibration drilling method for hole making in composite materials. The special feature of advanced composite materials is the difficulty of machining by conventional methods. The occurrence of defects such as matrix cracking, delamination and fibers failure, thermal degradation of matrix obtained in the process of making holes requires the development of new technological solutions and special equipment and tooling. As an alternative, along with cutting and abrasive machining methods for composite materials, we can consider vibration drilling, laser, ultrasonic and abrasive blasting machining of holes. The Department of Engineering Technologies and Equipment of Southwest State University has made a device intended for vibration drilling of holes in composite materials. Using the proposed method allows us to reduce the vibrations along the drill axis, both in the low-frequency and high-frequency range (20 to 500 Hz). It also allows us to change the frequency of vibration without stopping the cutting process. The device is designed for metall cutting machines related to drilling-and-boring group of machines with a vertical spindle to increase performance and improve the quality of holes shaping. Technical specifications of the designed device provide the set tool advances, the required frequency of spindle rotation, giving the necessary cutting speed (they depend on technical features of the selected machine), as well as the necessary amplitude and high frequency axial oscillations of the tool. To convert electric oscillations into mechanical ones there has been adopted the scheme of two inductance coils, being placed one above the other. The proposed method of electro-impulse drilling will solve the problem of processing composite materials (matrix cracking, delamination and fiber failures) and improve the quality and productivity of making holes in composite materials.

Forming the geometric accuracy and roughness of holes when drilling aircraft structures made from polymeric composite materials

“…-an integrated approach to the quality of the hole in PCM, which is based on the primary analysis of the kinematics of the tool's movement in PCM. This could be used to refine the results of electric pulse drilling [15], especially for uncut fibers and stratification of PCM at the input and exit of the hole; -the use of classic types of drills such as F, S, and UCE and can be used for the standard SECO SD290A-7.963 drill bit and drill bits with the new operational STS [16].…”

“…Despite the positive results reported in [14], they are insufficient to assess the quality of a hole according to such important parameters as the roughness and accuracy of the hole in AS made from PCM. According to the authors of [15], the proposed technique of electrical pulse drilling could solve the task of PCM machining (matrix cracking, stratification, and fiber breaks) and improve the accuracy and roughness of holes in AS made from PCM. This technique can be regarded as a new STS for drilling holes in PCM but there are no data on the non-cutting of fibers and stratification of PCM at the input and output of the hole.…”

“…The process of chip formation with any blade treatment of the hole in PCM made of carbon fiber and fiberglass is largely different from the blade machining of holes in metals where mainly drain chips are formed [15]. To understand the complete pattern of chip formation during PCM blade machining, consider the kinematic scheme of PCM chip formation by a cutting wedge (Fig.…”