The post-processing (punching or trimming) of high-strength parts reinforced by hot stamping requires punch molds with improved mechanical properties in hardness, resistance to wear, and toughness. In this study, a semi-additive manufacturing (semi-AM) method of heterogeneous materials was proposed to strengthen these properties using high wear resistance steel (HWS) powder and directed energy deposition (DED) technology. To verify these mechanical properties as a material for the punch mold for cutting, specimens were prepared and tested by a semi-AM method of heterogeneous material. The test results of the HWS additive material by the semi-AM method proposed in this study are as follows: the hardness was 60.59–62.0 HRc, which was like the Bulk D2 specimen. The wear resistance was about 4.2 times compared to that of the D2 specimen; the toughness was about 4.0 times that of the bulk D2 specimen; the compressive strength was about 1.45 times that of the bulk D2 specimen; the true density showed 100% with no porosity. Moreover, the absorption energy was 59.0 J in a multi-semi-AM specimen of heterogeneous materials having an intermediate buffer layer (P21 powder material). The semi-AM method of heterogeneous materials presented in this study could be applied as a method to strengthen the punch mold for cutting. In addition, the multi-semi-AM method of heterogeneous materials will be able to control the mechanical properties of the additive material.

Hydraulic excavators is the representative field robot and has been used in various fields of construction. Since the excavator operates in the hazardous working circumstance, operators of excavator exposed in harmful environment. Therefore, hydraulic excavator automation and remote control system has been investigated to protect from the hazardous working environment. Remote control system of hydraulic excavator needs a various equipments which is EPPR(Electro Proportional Pressure Reducing) valve, electronical joystick, video camera and monitor for virtual environment displayer, communication equipment of between controller and the real activity. In this paper , the method to construct the remote control system is proposed. The remote control system is consisted of a manual and automatic mode. Manual mode controls a hydraulic cylinder as open loop control and auto mode controls the end effect of excavator using tracking control system. Because of interactions between links and various working conditions. MRAC (Model reference adaptive control) based on variable structure is designed in this paper. The efficiency of remote control system was evaluated through the field test.