Research On Online Nondestructive Testing For Crack Of Anvil Of The Cubic Synthetic Diamond Press

The crack of cubic synthetic diamond press anvil is a common accident which happens in the production of synthetic diamond. If not found in time, it is extremely easy to cause greater economic losses, and even casualties. At present, there is no related application products on the design of the real-time detection system for crack of anvil and the detection of crack of anvil realizes depending on the listen mode recognition by the experienced workers. Therefore the design of the real-time detection system for crack of anvil has very strong realistic significance, and also is a key issue of industrial automation development of synthetic diamond industry.This paper presents a real-time detection and process scheme based on the acoustic emission testing through the analysis of the cause of crack of anvil, combined of its working condition. Combined with the method of sound recognition by the experienced worker at present, audio segment signal is selected as AE signal detection, and then discusses its reasonableness in theory. Acquisition of signal realizes using IPC sound card.This paper accomplishes the design acoustic emission detection module, including the selection of piezoelectric transducer element, shell design, and the signal conditioning circuit design such as power supply module design, signal amplifying and filtering circuit and so on. Sample the working signal of anvil using the designed acoustic emission detection module. The collected signal can be divided into 3 categories: low energy noise, suspected signal(vibration signal, which is caused by contraction of the preloaded ring because of the heating temperature impact and the synthesis of pressure fluctuations), signal of crack of anvil.The paper studies the anvil crack signal characteristic. Adopt the method of FFT、STFT and EMD to analysis the signal what is sampled. It comes to the conclusion. The characteristic frequency of suspected signal and crack signal is 200~400Hz and 2 KHz ~ 4 KHz. And it is obvious to find that the fault characteristic frequency of crack signal is 13 KHz ~16 KHz with HHT marginal spectrum from EMD.Write system software with C++, including sampling signal with sound card, GUI and multi-thread signal analysis framework. Design the endpoint detection algorithm based on short-time energy and short-time average zero crossing rates to capture the suspected signal and crack signal. Then Call COM component that packaged by Matlab to the signal analysis thread to identify crack signal.Now the detection scheme designed in this paper is tested in industry field depended on the fault characteristic extracted based on the collected signal. Continue to sampling signal and analysis signal to improved signal identification algorithm.