Solution of the inverse problem of creating a uniform magnetic field in coercimeters with partially closed magnetic systems

The use of a hybrid optimization technology by a swarm of particles with the evolutionary formation of swarm composition is considered together with the method of spatial integral equations in the synthesis of axially symmetric magnetic systems of coercimeters that contain ferromagnetic elements. The required uniformity of the magnetic field in the working volume is ensured by the optimal selection of the shape of pole pieces of a magnetizing device. A number of measures are proposed that allow acceleration of the synthesis process owing to shortening of the time spent for solving the problem of analyzing the distribution of the magnetic field in the working volume of the coercimeter.     

An attachable electromagnet of a coercimeter with an indicating system between the electromagnet’s poles

The dependence of the readings of a coercimeter on the gap width between an article and the poles of an attachable electromagnet (AEM) at different magnetizing and magnetization-reversing currents is studied in the case when the indicator of the magnetic state of an article is removed from the electromagnet’s magnetic circuit and placed between the electromagnet’s poles on the surface of the article. It is shown that, during coercive-force measurements, such an indicator cannot be used for determining the demagnetized state of the article in the case of substantial fluctuations of the gap between the AEM poles and the article, although it can be used for assessing the gap width.     

Calculation of the Reluctance of a Wedge-Like Air Gap of a Magnetic System

A method for the calculation of the reluctance of a wedge-like air gap between the face surface of the core of a magnetizing device and the surface of a magnetizing article is considered. A method for the transformation of a wedge-like air gap under a pole is described. The transformation is performed in a complex space by constructing an equivalent plane-parallel gap.     

The effect of a gap between the poles of an attachable electromagnet and a tested component on coercimeter readings and methods for decreasing it (Review)

The main drawback of a coercimeter with attachable electromagnets (AEM) is its sensitivity to a random gap between electromagnet poles and a tested article formed in the process of inspection. The causes of such sensitivity are analyzed and the methods for decreasing it are considered.     

The Magnetizing System of an In-Tube Flaw Detector with Transverse Magnetization

Results of calculations of the magnetizing system for a flaw detector are presented. The device is intended to determine longitudinal stress-corrosion cracks in pipes in underground trunk pipelines. The calculation results are compared to the experimental data obtained with a special model of the magnetizing device. The optimum parameters of magnetizing elements, as well as their mutual location that ensures the magnitude and direction of the magnetic flux in a pipeline's wall that are required for reliable identification of longitudinal defects, are determined. The obtained results were used as a basis for designing the magnetizing system's module, which is the main unit in each in-tube flaw detector.     

UNM-300/2000 Magnetizing Device and Its Use for Magnetic-Powder Testing Together with an MF-23IM Magnetic Meter

The destination, composition, and technical characteristics of a UNM-300/2000 magnetizing device are described and the domains of its use are presented. The question of the necessity of testing the magnetization and demagnetization processes is considered. The possibility and advantages of the mutual use of the UNM-300/2000 magnetizing device and an MF-23IM flaw-detection magnetic meter for carrying out magnetic-powder testing are analyzed.     

Permanent-Magnet Structuroscopes under Rotational Magnetization Reversal in a Material

Dependence of the readings of the sensor in a permanent-magnet structuroscope with a two-pole magnetizing device has been investigated for different directions of the magnetic-field transducer sensitivity axis with respect to the magnetization of a test article. The possibility for the devices to operate in a sensor rotation mode has been shown as applied to testing the mechanical properties of articles and the stressed-strained state of objects made of ferromagnetic materials.     

Study of arrangement efficiency of hall sensors of an attachable magnetic instrument used for recording the coercive force of a local area of an article

The use as a tested parameter of a coercimeter of the demagnetizing current that is measured at the moment of zero crossing of the magnetic flux in the magnet core by Hall sensors arranged under the electromagnet poles is shown to have an advantage over the use of the demagnetizing current measured at equal readings of Hall sensors placed in the neutral plane of the electromagnet in the leakage flux at different distances from an article.     

不锈钢单侧磁控电阻点焊工艺研究

为提高单侧焊接接头的质量,减少焊接缺陷,基于传统双侧轴向磁化装置,设计了一种适用于单侧电阻点焊设备的单侧径向充磁磁控装置。通过与传统电阻点焊进行对比性实验,研究了传统焊点与单侧磁控焊点随焊接电流的变化规律,揭示了单侧磁控电阻点焊装置对焊点熔核形貌、熔核尺寸、微观组织、力学性能等方面的作用机制及改善效果,验证了单侧磁控电阻点焊工艺的可行性。     

Magnetic inspection of the hardness of cast-iron milling rolls

The effects of the chemical composition and parameters of the cast-iron smelting and teeming process on the coercive force have been studied. It is shown that only chromium and carbon appreciably affect the coercive force. For rolls with cylindrical surfaces cast from ТПХН-60 iron, a reliable correlation has been established between the hardness and readings of a coercimeter with an attachable electromagnet. For flanges and blooming passes of sizing rolls made from ТШХН-50 cast iron, equations for the relation between the hardness and readings of a coercimeter have been obtained and analyzed. These equations can be used in nondestructive testing of hardness.     

Nondestructive Testing of Mechanical Properties of Rolled Steel (Review): 1. Tests of Strength and Plastic Properties

This review considers the creation and development of a nondestructive technique based on coercive-force measurements used to determine strength and plastic properties of industrial rolling products made from Russian-produced low-carbon and low-alloy steels. The operating principle for a coercimeter equipped with a field electromagnet is described briefly. Regression lines of mechanical properties versus coercimeter readings are presented for 20Κ- and 09Γ2-steel sheets produced by Nizhni Tagil Iron and Steel Works. Different methods for considering sheet thickness and tube dimensions are discussed.__________Translated from Defektoskopiya, Vol. 41, No. 5, 2005, pp. 39–52.Original Russian Text Copyright © 2005 by Bida.     

冲压零件尺寸合理标注的研究

通过对某冲压件厂生产中出现的冲压件废次品抽检结果进行分析,指出冲压零件尺寸标注不当是影响产品质量的一个重要原因,并提出了冲压零件尺寸合理标注的注意事项.     

Dynamic model of a continuity flaw during normal magnetization of a ferromagnetic article: II. Magnetostatic field of a continuity flaw during magnetization of the article with a finite-sized magnetizing instrument

A dynamic model of a finite-sized continuity flaw that is present in a ferromagnetic half-space during normal magnetization with a magnetic field produced by a bar magnetizing instrument is obtained. The model takes into account the relative position of the flaw and magnetizing system during the model’s motion along the surface of an article. During normal magnetization of the flaw with the field produced by the finite-sized bar magnet, the longitudinal component of the magnetizing field is shown to exist. The longitudinal component distorts the magnetic-field distribution of the continuity flaw and decreases its detectability.     

一种新颖的磁浮轴承电度表

本文介绍一种应用轴向磁浮轴承支承电度表转盘的新方法，其精确度和灵敏度高、而且不受温度变化及电度表位置倾斜等影响。     

钢棒纵向裂纹漏磁检测方法

介绍钢棒螺旋前进、励磁器和检测探头均固定不动的检测方法,避免旋转探头检测中,滑环的大电流和多通道信号传输问题,确保足够的励磁电流和更多通道的稳定信号。研究了不同规格钢棒需要的有效励磁强度和检测探头靴的设计要点,提出了高灵敏度和稳定性的探头靴设计方法。     

Magnetic testing of the inclination to crack formation when forming rolls from йQhQxX16QMQl white iron

The correlation between the coercive force and the hardness of roll sections (butt ends, ledges, and passes) with and without cracks is investigated. It is demonstrated that inclination to crack formation can be controlled by the spread in coercimeter readings on a specific roll surface.     

The modern features of equipment for magnetic structural analysis

The new MC-10 magnetic structure analyzer is intended for the determination of different characteristics of materials and products by measuring coercive force. The MC-10 structure analyzer is compared with its older analogues: the KPM-Ц-K2M magnetic structure analyzer and KИM-2M coercimeter.     

Evaluating the structure of a ferromagnetic material based on magnetic-field strength between the poles of an attached two-pole magnetizing device

The possibility for using a magnetic structoroscope with a two-pole permanent-magnet magnetizing device to test mechanical properties of stressed-deformed state of articles made of ferromagnetic materials has been investigated. Dependences of equipment readings on the geometrical dimensions of the structuroscope sensor and on the deformation of ferromagnetic material of a sample in tension in the elastic loading–unloading domain are presented for samples made of different ferromagnetic materials.     

Nonuniform magnetization of an article around a flaw during magnetic inspection

Measurements of the induction in a ferromagnetic article directly around a surface flaw in the form of a rectangular slot have shown that there is a substantial magnetization nonuniformity of the article owing to the discontinuity. The nonuniformity smooths out as magnetizing field H ₀ increases. The increase in magnetizing field H ₀ increases the nonuniformity of the field distribution over the article surface, thereby changing the topography of the flaw field. In particular, in low magnetizing fields, this change leads to the absence of negative extrema in the curve of the tangential component of the flaw field, H _x (x). The discrepancy between the calculated and experimental values of the fields of flaws characterized by different geometric parameters is indicative of a considerable effect of the flaw opening on calculated data. These data should be improved through proper corrections obtained experimentally.