Research And Development Of Auto E.c.t. System For The Roll

Roll is a very important manufacture part used in the strip mill plant. If we put the roll into use with some crack on its surface, the roll broken accident is very easily happened during production. So in order to avoid this accident, we must check every roll surface before it is put into the mill. Eddy current test is a universal N.D.T. method we use. In the roll shop of Baosteel hot strip mill plant, there are some automatic E.C.T. devices installed on the roll grinding machines for detecting the crack on the roll surface. These detectors were imported from ASKO, an America company in 1995. The operation software of the detector is running on DOS OP system. The function is very simple and the design of these E.C.T. devices also has some problem. For these reason, the E.C.T. device can not meet the requirement of the fast pace production. The purpose of this study is re-designing a new E.C.T. detect system in order to solving the problems in the E.C.T. detector we use now and to meet the requirement of the production.The 2nd chapter of the paper starts from the principle of the eddy current generation and the feature of the eddy current. With this basis, the paper uses the equivalent circuit method to makes a conclusion that the essence of eddy current test is measuring the variety of the resistance of the coil, and analyses the factors which cause the change of the resistance of the coil by the equivalent circuit. The chapter also introduces the principle of the measurement of the variety of the coil resistance and the process of the modulation and demodulation of the defect signal. The 3th chapter of the paper introduces the structure and the characteristic of the automatic eddy current detector which is installed on the grinding machine for the roll surface scanning, emphasizes the main factor due to the gap variety, and introduces the general method to eliminate this influence. Additionally, the paper introduces the other problems of the detector design in detail, and also offers the method to solving these problems.The 4th and 5th chapter of the paper introduces the hardware design and the software design of the new E.C.T. system. For the hardware design, the paper makes focus on the design of the test head system, the signal process unit, the circumferential and axial coordination collecting system. For the software, the paper introduces the design of the single chip system and the industrial PC system. The paper also discusses the communication between the detector and the grinding machine. Additionally, the paper introduces the design of the HMI.The 6th chapter estimates the stability and the accuracy performance of the new E.C.T. system based on the experimentation data. Finally, the paper prospects the future of the automatic eddy current detect system, makes the conclusion that in the future the combined testing technology will be used in the E.C.T. system. And with the increasing of the production scale, more and more E.C.T systems will be installed in the roll shop, at that time the central control technology and the network technology will also be used in the E.C.T. system.