Experimental study of rotary ultrasonic high-quality hole processing of Glass Fiber Reinforced Plastic with a new diamond trepanning bit

Glass Fiber Reinforced Plastic is widely used in manufacturing and other fields because of its high specific strength and high specific modulus. Since the workpiece requires secondary hole processing during assembly, machining defects are prone to occur during hole making, which seriously affects the service life of the workpiece. A novel type of thin-walled diamond trepanning bit was fabricated and combined with ultrasonic processing technology to conduct a pilot study on hole processing. Compared with conventional twist drill hole processing, the novel diamond trepanning bit grinding hole-making method can significantly reduce the axial force when drilling, and effectively reduce the delamination and tearing damage at the exit of the hole, so that the delamination ratio at the exit is reduced by 9.6%. Combined with ultrasonic machining technology, hole machining experiments were carried out, and the results showed that: spindle speed increase or feed rate reduction can make axial force, hole wall surface roughness, and exit delamination damage all show a decreasing trend. Compared with conventional machining, the rotary ultrasonic hole machining technology can effectively reduce the axial force by 20.1% and effectively reduce the exit delamination problem by 7.3% in the delamination ratio. At the same time, considering the hole-making quality and efficiency, rotary ultrasonic processing can better reflect the advantages of the process and obtain better hole-making quality at the speed of 3000–4000 r/min and the feed rate of 14–20 mm/min. The above research can provide theoretical and technical support for the hole processing problems of Fiber Reinforced Plastic, which has important engineering application value.