Eddy current probe to detect longitudinal discontinuities such as seams of wires and bars has been discussed. Conventional encircling coil is hard to detect the longitudinal discontinuities because of the fundamental principal restriction. Moreover, a system using a rotating probe hardly has an ability to support high-speed inspection. Therefore, a probe with array sensors has been developed to detect the longitudinal discontinuities without mechanical rotor. The spin-valve type giant magnetoresistance (SV-GMR) sensor was used as the detection sensor. It has advantages in high sensitivity, high frequency response characteristic up to 100 MHz, and the integration of the sensor element compared with coil or other magnetic sensors. The probe is constructed from two excitation coils and 36 detection sensors. The excitation coils are encircling type such as the conventional encircling coils and excited by opposite phase each other. The detection sensors are arranged in the directions of surrounding a rod for examination between excitation coils. The probe has the capabilities to detect the longitudinal notches by sequential scanning with detection sensors. In addition, a correction method for eccentric effect is proposed by taking the addition of signals at position of opposed sensor pair. The present study showed that the probe has the ability to detect the longitudinal notch that depth of 0.3 mm with 5 mm air gap.
Various nondestructive testing have been applied for steel products in manufacturing processes. Ultrasonic inspection is an important method to evaluate inclusions in rolled billets. Conventional ultrasonic transducer with a flat piezoelectric element is used for the inspection. However, ability of inspection for a part of chromium stainless steel billets with coarse grain is insufficient with comparison to the ability for carbon steel billet. This paper describes a result of development of new ultrasonic transducers for the billets with coarse grain. Numerical analysis with finite element method was carried out to make sure a best frequency and wave shape. Two transducers are designed and confirmed advantages over the conventional transducers.
Over the past few decades nonlinear ultrasonic has been researched actively for the purpose of inspection technology for closed clacks or estimation of bonding quality of dissimilar materials. Nonlinear ultrasonic is a harmonic signal generated by a material’s nonlinear stress-strain relation or nonlinear reflection phenomena at a closed crack. Considering the practical application of the signal, it is indispensable to establish a calibration method. Reference reflectors, such as flat bottom holes or back wall, are used in the application of conventional pulse echo ultrasonic inspection. However, calibration methods of the nonlinear ultrasonic signal have not been established yet. This paper is intended to investigate calibration method of nonlinear ultrasonic signal. A convex Newton lens was utilized for the purpose of understanding acoustic signal response around a narrow gap. A new calibration test block made of stainless steel was designed to generate a harmonic signal. As a result, effectiveness of calibration of nonlinear ultrasound signal using the block was confirmed.
It is difficult for the application of the image processing technology for the processing metal surface inspection to get the satisfaction of the user by various kinds of fluctuation factors in the processing process. We developed an image filter processing to get resemblance degree distribution of every adjacent local domain that was near to algorithm of the human visual inspection. And this image filter was able to emphasize a defect part to the exclusion of various fluctuation factors. As a result, we are able to promote better automation of various processing metal surface inspection.
Non-contact three-dimensional measurement has been widely applied recently. This is because the measurement enabled a new type of shop-floor production (monodukuri) which increased the productivity and made it possible to measure free-form surface which had been impossible in the past. Triangulation 3D scanner is an equipment that realizes the three-dimensional measurement. Especially, the laser probe method is less subject to the color and the luster of the object, so it is a very worthwhile way to measure industrial instrumentation. Details of the scanner are described in this article.
Most all rolled steel produces such as wire rods or round bars are inspected its surface and internal quality by inline automatic flaw detector, whereas forged or caste products which rather have complicate shapes are inspected its surface quality by visual inspection. These days, machine vision technology has been made a great progress. Speed, accuracy and environment of developing applications were improved rapidly. Machine vision system became a subject of investment in plant and equipment for the purpose of taking over the visual inspection made by operators. This review summarizes subjects of inspection of steel products, overviews recent technical progress of machine vision system and introduces a state of conditions of application of the machine vision system to factories.
As one of the quality control for chemical composition of materials, spark test and Color Identification Test have been used at Shibukawa plant. However, both tests do not perfectly inspect chemical composition for all materials because the results of tests are not decided by actual data but rely on inspector’s skill. To improve it’s accuracy, a portable x-ray analysis machine was technically evaluated and has been introduced as a new test for chemical composition analysis. Chemical composition analysis in final inspection has been improved since the portable x-ray analysis machine is used at time. Identity management system has been improved by more accurate test, which can be realized with construction of EDP (Electronic Data Processing) system using x-ray test data. Whole system was improved in conjunction with the improvement of portable x-ray analysis machine. And 10 machines have been installed in places in the plant and contributed to improve the accuracy of the identity management. An outline of the system is described in this article.
DLCC (Daido Low pressure Cold box Casting) is applied for turbine housing manufacturing process in Daido Castings Co.,Ltd. In this method, molten metal is vacuumed up to the mold in reduced pressure and kept untill the metal is solidified. However, the molten metal is leaked out from the molds if there is a crack or a gap between the molds. As a result, hard labor and a great expense are needed as well as scrapping the products. For the puropose of preventing the disaster, an equipment for detecting cracks or gaps between the molds has been developed and installed just before the casting process. MEMS air flow sensing device is used to detect minute leak air from cracks or gaps between the molds. The aim of this paper is to give an outline of the development.
An automatic inside diameter gauge for arm vane has been developed. Arm vane is an important constituent part of a variable vane assembly that adjusts quantity of turbo-charger exhaust flowing. A hole is machined at the edge of the arm. It is necessary to manage the size of the hole strictly. In the gauge, two optical systems are used to measure the diameter of the hole from upper and lower sides. Diameter of a maximum inscribed and minimum circumscribed circle are calculated by an image processing to judge the quality of the hole. Part is inspected in 1.8 seconds with ±5 μm of repetition accuracy. Result of a performance test was 100 % detection of defective parts with 5 % over detection of good parts. Details are described in this article.