워터젯에 의한 난삭재 3D 형상 밀링가공 특성

Abstract

Recently, an attempt to use waterjet as a tool for abrasing of hard-to-machine materials, such as titanium and composites.

When abrasing those materials with the conventional tools, rapid tool wear and thermal deformation are generated. Since waterjet process does not produce such kind of problems, the waterjet process are adopted for various machining for the hard-to-machine materials.

In principle, water is pressurized with ultra high pressure with up to 3,000 bar or more with a high pressure pump for waterjet process and abrasive powder materials are mixed before injected to the target materials through an orifice and a nozzle for manufacturing.

In this study, the influences of the cutting conditions of the abrasive waterjet such as pump pressure, feed rate, abrasive mass flow rate, SOD, onto the machining characteristics of the target materials are investigated.

The cutting depths by the impact angle and by the overlap ratios have been measured for the materials, Ti6Al4V, SUS 304, and Inconel 600. From this, it has been verified that Ti6Al4V was the best machinability and Inconel 600 was the lowest machinability.

It has been found that the cutting depths of AWJ increase the pump pressure and the amount of abrasive increase. On the contrary, the cutting depth of AWJ decrease as the feed rate of the mixed waterjet and S.O.D increases.

It has been confirmed that the cutting depths increased by about 1.78 times as the overlapping ratio of the machining paths increased. It has been also confirmed that the surface roughness becomes less rough as the impact angle approaches 90°to the workpiece, since the water and the abrasive materials injected out from the nozzle become regular spreading.

It has been verified that the waterjet cutting depth error was 10% less than those results obtained by 3D machining simulation.

It is expected that the experimental results obtained through this study can be used as fundamental data for AWJ milling for various hard-to-machine materials.