CUTTING SPEED AND FEEDRATE BASED ANALYSIS OF CUTTING FORCES IN THE ONE SHOT DRILLING (OSD) OF CFRC/AL HYBRID STACKS

摘要

Hybrid stacks structures Composite/Metallic Alloy are commonly applied for manufacturing of structural components in different industrial sectors. Particularly, they are increasingly widely used in the aerospace industry because of these materials combine light weight with a high mechanical resistance. This fact helps to increase the load without needing to increment -even diminishing- the energetic consumption. Carbon Fiber Reinforced Composites (CFRC) and light alloys, such as Aluminium or Titanium based alloys, are usually combined for performing those stacks. CFRC/Alloy stacks based airship structural elements commonly require drilling operations for the posterior assembly tasks. However, the machining processes of Non-Metal Matrix Composites (NMMC), and particularly CFRC, show significant differences with the machining processes of metallic materials. Because of this, it is very difficult to find a joint only one of cutting parameters for drilling these structures using One Shot Drilling (OSD) techniques. In this work, a study of the cutting forces developed in the dry-OSD of CFRC/UNS A92024 stacks has been achieved as a function of the cutting speed and feedrate parameters. Dry drilling tests have been performed using different parameters for drilling CFRC and alloy. A change of the parameters in the interface between CFRC and the alloy has been programmed through a CAM software. Higher cutting force values have been observed in the case of the Aluminium alloys. For both materials, obtained results have shown a strong increase of the cutting force with the increase of feedrate. However, only a slight increase with cutting speed has been observed. The evolution of the cutting force as a function of the holes number has shown a trend to increase only for highest feedrates when CFRC/Alloy is drilled. From the obtained results a F(f.v) model has been proposed.