Jung Do Suh

Composite machine tool structures for high speed milling machines

Abstract To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to welded steel structures using adhesives. These composite structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ± 5μm per 300 mm of the slide displacement.

Manufacture of composite screw rotors for air compressors by RTM process

Abstract Screw rotors, the key parts of screw compressors, are widely used in compressing air and refrigerant due to their high productivity, compact size, low noise and easy maintenance. In general, a screw compressor unit is composed of female and male rotors of complex geometric shape. The manufacturing cost and time of the screw rotors are high because the complicated helical shapes of the screw rotors are manufactured usually by dedicated machine tools. In this study, to reduce the production cost and weight of screw rotors, the screw rotors for air compressors were manufactured with chopped carbon fiber epoxy composite materials by the RTM (resin transfer molding) process using separable four-piece molds for easy demolding of helical shape screw rotors.