As emission regulation of vehicles is being reinforced globally, the current requirement of the automobile industry are innovative green technologies that reduce the weight of the vehicle, thereby improving fuel consumption and the amount of exhaust gas emission. The application of ultra-high strength steel (UHSS) for vehicles has specifically been studied for light weight of vehicles. UHSS withstands greater loads than a general steel sheet of the same thickness. The spring-back and formability of the UHSS are also worse than general steel sheet due to their high elasticity and high yield strength. Various methods applied for processing UHSS include roll-forming and hot-press forming. However, these processes have not only high installation cost but also low productivity. This study therefore developed the cold-press forming method to overcome these disadvantages. The objective of this study is to determine the optimum conditions of the cold press required to form the upper seat track using UHSS. Forming analysis predicted the spring-back at each stage of the press forming. The prediction of spring-back was compared with the manufactured upper seat track by try-out, thereby reducing trial and error in the pressing process.

The shell body is the main exterior part of a compressor, and production of shell bodies has increased along with a growing demand for air conditioners, refrigerators, air compressors, and so on. Cracks frequently occur in the process of welding a shell body. In this study, a deep drawing process for creating a shell body from a blank is developed. The technique consists of a four-step deep drawing and a two-step trimming process. Analysis is performed by DEFORM software to examine the safety of the deep drawing and trimming processes. The deep drawing process for the shell body developed in this study would have wide application in many industrial fields.

Laser assisted machining (LAM) is an effective method with which to effectively process difficultto-cut materials. Simple machining processes, such as turning and linear tool paths, have been studied by many researchers. But, there are few research efforts on LAM workpieces using threedimensional shapes because of difficulties controlling the laser heat on workpieces with inclined angles or curved surfaces. Two methods for machining three-dimensional workpieces are proposed in this paper. The first is that the heat source shape and laser focal length are maintained using an index table. Second, a rotary type laser module is controlled using an algorithm to move the laser heat source in all directions. This algorithm was developed to control the rotary type laser module and the machine tool simultaneously. These methods are verified by a CATIA simulation.

LAM (Laser-Assisted Machining) is an effective method for processing difficult-to-cut workpieces. The focal length of a LAM system is changed by the change of the workpiece shape during laser preheating; this problem is solved by changing the lens of the laser module. Linear- and rotarytype lens changers were developed to change the laser lens of a LAM system. The linear-type lens changer is operated by a motor with a ball-screw, and the rotary type is operated by a stepping motor. The natural frequency and structural stability of the laser lens changers were confirmed by using a finite element analysis; in addition, the functions of the lens changers were verified by measuring the iterative accuracy. The measured results show that the rotary-type lens changer is more accurate than the linear-type changer.