# Real-Time Penetration Recognition Based on Voltage Signal in K-TIG Welding
## 2 Materials and Methods  
The experimental setup employed in this study is illustrated in Figure 1. It comprises four essential components: the K-TIG welding component, the programmable logic controller (PLC) motion component, the industrial personal computer (IPC) control system component, and the signal sensing component. The K-TIG welding component encompasses the control system and the control system. The K-TIG welding component encompasses the control system and the control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system and control system. The control system is designed to control system system and control system. The control system is designed to control system system and control system. The control system is designed to control system system and control system system. The control system is designed to control  
passes a DC welding power source, a cooling water supply system, and a specialized welding gun for K-TIG welding. The PLC motion component provides three degrees of freedom, facilitating control over the welding gun's movement. During the welding process, the current and voltage are measured by Hall sensors, which are protected by a protection circuit equipped with a differential amplifier. The IPC control system is responsible for acquiring data and adjusting welding parameters, while the National Instruments USB-6251-BNC acquisition card is employed to capture the current and voltage signals at a sampling frequency of 200 kHz. To attain different penetration states, two identical 304 austenitic stainless steel plates (300 \(\times\) 150 \(\times\) 10 mm) are assembled and utilized for the welding experiments. During the experiment, the two plates are brought together to create a gap of 0. Ar is used as the shielding gas with a flow rate of 20 L/min, while the CTWD was controlled at 3 mm, and the welding torch is facing the splicing part of the two plates. The power supply used in the current research is an efficient deep penetration arc welding machine produced by Guangdong Fuweide Welding Co., Ltd., with the model K-TIG1000 (Guangdong Fuweide Welding Co., Ltd., Huizhou, China); the signal acquisition card is the National Instruments USB-6251-BNC (National Instruments, Austin, TX, USA). The PLC control system, XYZ motion platform, and IPC control system are developed by Shanghai Lianqing Power Technology Co., Ltd. (Shanghai Lianqing Power Technology Co., Ltd., Shanghai, China). During the experiment, the gap between the welded plates is controlled to be zero, and the K-TIG welding technology is used to obtain a completely melted trial plate with a welding current of 525 A and a welding speed of 240 mm/min. To control variables and study different welding quality results, the researchers adjust another experimental parameter while keeping either the welding current or welding speed constant. The specific welding parameters are shown in Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Welding Parameters** & **Value (Speed)** & **Value (Current)** \\ \hline Welding current & 525 A & 450, 480, 500, 525, 550, 570, 600 A \\ Welding speed & 160, 180, 200, 220, 240, 280, 300, 320, 360 mm/min & 240 mm/min \\ Gap & 0 mm \\ CTWD & 3 mm \\ Flow rate & 20 L/min \\ Shielding gas & Pure argon (99.9\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Test parameters. Figure 1: Schematic diagram of the welding experiment system.