JP2008292335A - Chilled structure evaluating method and device for cast part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chilled structure evaluating method and device for a cast part, simply and accurately measuring the presence/absence of a chilled structure of the cast part. <P>SOLUTION: This chilled structure evaluating device 100 for the cast part includes: an electromagnetic induction sensor 10; a sensor holding means 20; an alternating current power supply 30; a detecting circuit 40; a recording part 50; a display part 60; and a storage part 70, wherein the electromagnetic induction sensor 10 includes an exciting coil and an induction coil, which are coaxially formed integral, in inspecting on whether or not chilled structure exists in the cast part, an alternating current is applied to the exciting coil to form a magnetic field, and a change in the magnetic field formed by the exciting coil of the cast part 1 is detected by the induction coil, and between the amplitude and the phase of the induced electromotive force generated in the induction coil, for example, a change amount of at least one of them is measured to detect the presence/absence of chilled structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for evaluating a chilled structure of a cast part that can easily and accurately measure the presence or absence of a chilled structure (chill structure) of a cast part using an electromagnetic induction sensor.

  Cast parts such as gas pipes and reinforcing steel joints are made of cast iron, as are structural parts such as automobiles, ships and construction machinery. Cast iron is roughly divided into two types, gray cast iron and spheroidal graphite cast iron, based on the shape of graphite inside. The former contains a large number of flake graphite inside, which acts as an internal notch, and is generally a low-reliability material with low strength and varying strength. However, since it has good castability and balanced industrial properties, it is a general-purpose material widely used as a casting part. On the other hand, the latter is obtained by spheroidizing flake graphite and exhibits high strength and high toughness. In recent years, it has been required to reduce the thickness of spheroidal graphite cast iron parts as the weight and size of cast parts have been reduced.

The matrix structure of cast iron ranges from a complete pearlite base to a complete ferrite base, and the ratio of these bases varies depending on manufacturing conditions. The ferrite matrix has excellent ductility and improves the toughness of the cast iron material, but has the property of reducing the strength. On the other hand, pearlite base is hard and increases the strength of cast iron material, but has the property of decreasing toughness. Therefore, the area ratio of ferrite base and pearlite base in cast iron is an important parameter that determines the mechanical properties of cast iron. Further, in cast iron, a large cementite Fe ₃ C structure may be generated at a location that is further rapidly cooled in the production process. This cementite structure is the hardest, brittle and easy to break in the cast iron structure. Therefore, cast parts with high strength, such as joints for reinforcing bars, are thin, so that a chilled structure is likely to occur, and if there is a chilled structure, it is treated as a defective product.

  Regarding the cause of the occurrence of the chilled structure in the cast part, the solidification process of the cast iron melt starts with primary crystal solidification and is completed with eutectic solidification, but the generation state of the chilled structure is mainly determined at the time of eutectic solidification. There are two types of eutectic solidification: graphite eutectic solidification (stable solidification) and cementite eutectic solidification (metastable solidification). The metal structure that crystallizes by the latter solidification is called a chilled structure. .

  For example, in the case of a reinforcing steel joint, since it is thin, a chilled structure is likely to occur particularly at the end. There are various ways of thinking about this phenomenon. Here, the chill critical cooling rate (Rc) will be described.

  Rc is a boundary condition that is divided into graphite eutectic solidification (normal structure) and cementite eutectic solidification (chilled structure) at the cooling rate.

  In this case, the degree of influence of each element on the chilling tendency is evaluated as a change in Rc with respect to its content. For example, RcA of cast iron melt A with C content = 3.4% and Si content = 1.12% = 123.2 ° C./min, whereas RcB of cast iron melt B with C content = 2.29% and Si content = 2.04% = 160.6 Increased to ℃ / min. An increase in Rc means that chill is less likely to occur, and this change in value numerically represents the chill prevention effect by Si. FIG. 8 schematically shows the chill generation state when a thin casting is cast using these two types of cast iron melts.

  FIG. 8 shows an example of the cooling rate distribution from the casting end surface to the center, but the cooling rate is maximum at the casting end surface (170 ° C./min in this example), and decreases toward the casting center. In the case of casting A, since the cooling rate exceeds RcA (123.2 ° C./min) at all positions, the entire surface is a chilled structure. On the other hand, in the case of the casting B, the cooling rate in the range from the end surface to the point a exceeds RcB (160.6 ° C./min), so that it becomes a chilled structure, but at the center side, it becomes smaller than RcB. It becomes a normal tissue.

  Thus, as the value of Rc decreases, a chilled structure is more likely to be generated. First, the chilled structure generated on the end surface as in the case of casting B has a chilled region toward the center as Rc decreases. As the casting A expands, the entire surface becomes a chilled structure.

  From the above, when determining the presence or absence of a chilled structure for a thin cast part or the like such as a reinforcing steel joint, the chilled structure near the end may be determined. If the end is a normal tissue, it is not considered that a chilled tissue is generated in the center. Conversely, just confirming that there is no chilled structure in the center does not prove that there is no chill at the end face, so there is a problem in determining the overall chill presence or absence.

  That is, for joint members such as reinforcing steel joints, it is important to strictly control the manufacturing process and at the same time inspect the material and existence of defects. Therefore, a simple and reliable method for evaluating the chilled structure of a casting part such as a joint member is required.

  Conventionally, techniques for casting defect inspection and material evaluation have been developed mainly for ultrasonic cast iron evaluation, and it has become possible to evaluate the graphite spheroidization ratio related to tensile strength.

  However, evaluation of the structure of cast parts (for example, evaluation of the presence or absence of a chilled structure) has not been solved. Currently, no non-destructive evaluation method has been established for the evaluation of the structure, for example, the presence or absence of a chilled structure. In order to investigate the material and mechanical properties, a microscopic observation by cutting and polishing, a hardness test, a tensile test, etc. must be performed. Don't be.

  Therefore, the inspection technique using ultrasonic waves not only requires a lot of cost and labor, but also has a problem that it is impossible in principle to inspect all cast parts. On the other hand, if the distribution of the chilled structure of the cast part can be easily grasped in a non-destructive manner, the result of the cast part can be easily reflected in the design. At present, it is very difficult to control or improve the material in the casting part manufacturing process because the material evaluation cannot be performed easily. Simple nondestructive evaluation facilitates feedback to the manufacturing process, which has been difficult until now, and can optimize the manufacturing method. For example, this leads to higher performance and improved reliability of cast parts such as further reduction in thickness and weight.

  Therefore, in recent years, a nondestructive evaluation method for cast iron using magnetism has been proposed (for example, see Patent Document 1).

  As a nondestructive evaluation method for cast iron, a method called an eddy current method is conventionally known. This eddy current method is a method that uses eddy current generated in a test object by induced electromotive force when a coil to which an alternating current is applied is brought close to a conductive test object. Since the magnitude and distribution of the eddy current generated in the object to be inspected change depending on various conditions such as defects and shape dimensions of the object to be inspected, the inspected object can be obtained by extracting the change in magnetic flux due to the eddy current generation state It can be inspected for the presence or absence of defects, shape change, etc., and is widely used. The relationship shown by the following formula | equation is known between the frequency of the alternating current applied to a coil, and the induced electromotive force which generate | occur | produces in an electroconductive to-be-tested object.

但し、Ｅ：起電力、ｆ：周波数、Ａ：定数を示している。故に、一般的に渦電流法では検出感度を向上させるために、コイルの交流電流の周波数を高めて、被検査体に生じる誘導起電力（渦電流）を大きくする方法がとられている。

Here, E: electromotive force, f: frequency, A: constant. Therefore, in general, in order to improve detection sensitivity in the eddy current method, a method is adopted in which the frequency of the alternating current of the coil is increased to increase the induced electromotive force (eddy current) generated in the object to be inspected.

JP 2003-262618 A

  However, the above-described eddy current method has a problem that it is not suitable for detection of a deep portion of an inspection object. This is called the skin effect and is expressed by the following equation.

但し、δ：浸透深さ、ｆ：周波数、μ：透磁率、σ：導電率を示している。これは、被検査体に生じる電磁界が表面近くに集中し、深部になると急激に減衰することを表しており、周波数が高いほど減衰が大きいことを示している。そのため、高い周波数を印加する渦電流法では、表面近くの検出感度は高いが、被検査体の深部の検出には適していなかった。

Where δ: penetration depth, f: frequency, μ: magnetic permeability, σ: conductivity. This indicates that the electromagnetic field generated in the object to be inspected is concentrated near the surface and attenuates abruptly as it goes deeper, and the higher the frequency, the greater the attenuation. Therefore, the eddy current method in which a high frequency is applied has a high detection sensitivity near the surface, but is not suitable for detecting a deep portion of the object to be inspected.

  In the case of the eddy current method, the surface state of the inspection object greatly affects the detection sensitivity. Therefore, for example, when it is desired to detect a defect such as a welded sample or a cast sample having fine irregularities on the surface, a pretreatment such as smoothing the surface or removing the oxide film or coating film is required. Furthermore, in the eddy current method, since the distance (lift-off) between the coil and the surface of the sample greatly affects the detection sensitivity, there is also a problem that the shape of the sample that can be measured is limited.

  At present, in order to determine the presence or absence of a chilled structure of a cast part such as a joint for a reinforcing bar, for example, the end of the joint member, i.e., the part where the chilled structure is likely to occur, is squeezed to determine the presence or absence of the chilled structure to decide. Therefore, inspection of defective products is difficult and efficiency is low.

  The present invention has been made in consideration of such problems. An electromagnetic induction sensor that can detect not only the surface of a cast part but also the deep part or the inside thereof without pre-processing the cast part (inspected object). Is used to accurately measure the presence or absence of a chilled structure of a cast part, and to provide a chilled structure evaluation method and apparatus for a cast part that can solve the weaknesses of conventional nondestructive evaluation.

  In order to solve the above problems, a chilled structure evaluation method for a cast part according to the present invention includes an exciting coil that applies an alternating magnetic field to the cast part as a sensor that detects the presence or absence of a chilled structure of the cast part, An induction electromotive force generated in the induction coil due to a change in the alternating magnetic field by the casting part using an electromagnetic induction sensor having an induction coil for detecting the magnetic flux density of the alternating magnetic field applied to the casting part from the excitation coil It is characterized in that the presence or absence of the chilled tissue is detected by measuring the amount of change of at least one of the amplitude and the phase.

  For example, the electromagnetic induction sensor is inserted into the casting part, and the presence or absence of a chilled structure is detected with respect to the entire circumference of the electromagnetic induction sensor insertion portion of the casting part. Further, the frequency f of the current applied to the exciting coil is set to 10 kHz ≧ f ≧ 0.1 kHz, and the number N1 of the exciting coil and the number N2 of the induction coil are set such that 1000 ≧ N2 ≧ N1 ≧ 50. The casting part is a joint member for gas piping and reinforcing bars.

  Moreover, in order to solve said subject, the chilled structure evaluation apparatus of the cast component which concerns on this invention is an exciting coil which provides an alternating current magnetic field to the said cast component as a sensor which detects the presence or absence of the chilled structure of a cast component. And an induction coil for detecting the magnetic flux density of the alternating magnetic field applied to the casting part from the excitation coil, and a predetermined distance from the surface of the casting part as the measurement object. A sensor holding means for approaching and holding the position of the casting, and a casting component based on the amount of change of at least one of the amplitude and phase of the induced electromotive force generated in the induction coil due to the change of the alternating magnetic field by the casting component. A judging means for judging the presence or absence of a chilled structure, and an output means for outputting that when the judging means judges that there is a chilled structure of a cast part. The features.

  For example, in the electromagnetic induction sensor, the frequency f of the current applied to the excitation coil is set to 10 kHz ≧ f ≧ 0.1 kHz, and the number N1 of the excitation coil and the number N2 of the induction coil are set to 1000 ≧ N2 ≧ N1 ≧. 50 relationships.

  Further, for example, when the casting part is cylindrical, the sensor holding means holds the electromagnetic induction sensor inserted in the joint member on the central axis of the casting part.

  Further, the cast part is a joint member for gas piping and reinforcing bars.

  The present invention measures the change amount of at least one of the amplitude and phase of the induced electromotive force generated in the induction coil due to the change of the alternating magnetic field by the cast part, thereby chilling structure of the cast part, ferrite phase・ Accurately measure the presence or absence of a chilled structure in a cast part based on the difference in electromagnetic properties of the pearlite phase, and accurately and non-destructively evaluate the presence or absence of a chilled structure in a cast part that was previously impossible. Can be easily obtained. Further, the presence or absence of a chilled structure of the cast part can be measured without contact between the electromagnetic induction sensor and the cast part.

  In addition, there is no need for pre-treatment such as smoothing the surface of cast parts (measured products) for inspection or removing oxide films and coatings as in the past, saving costs and labor. it can. In addition, the sensory test for determining the presence or absence of the chilled structure by removing the portion where the chilled structure is likely to occur is abolished, and the total number of cast parts can be inspected. Furthermore, since the distribution of the chilled structure of the cast part can be easily grasped by nondestructive evaluation, the inspection result can be easily reflected in the design, and the manufacturing method can be optimized. Therefore, it has the effect of reducing the weight and performance of cast parts.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a cast part chilled structure evaluation apparatus and a cast part chilled structure evaluation method using the same according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a chilled structure evaluation apparatus for cast parts as an embodiment. FIG. 2 is a diagram illustrating a configuration of the electromagnetic induction sensor 10. FIG. 3 is an enlarged view of a portion where the electromagnetic induction sensor 10 of the casting part 1 is installed.

  As shown in FIG. 1, the cast part chilled structure evaluation apparatus 100 includes an electromagnetic induction sensor 10, a sensor holding unit 20, an AC power source 30, a detection circuit 40, a recording unit 50, a display unit 60, And a storage unit 70.

  The electromagnetic induction sensor 10 is held close to a predetermined distance from the surface of the casting part 1 by the sensor holding means 20 while being inserted to a predetermined position L (for example, L = 25 mm) at the end of the cylindrical casting part 1. Installed. In this case, measurement is performed on the entire circumference of the electromagnetic induction sensor insertion portion of the casting part 1 using the magnetic field around the tip of the electromagnetic induction sensor 10.

  Further, the cast part 1 is fixed by the support means 2. An AC power supply 30 and a detection circuit 40 are connected to the electromagnetic induction sensor 10.

  In this example, a reinforcing bar joint was used as the cast part 1. As described above, since the reinforcing steel joint is thin, a chilled structure is likely to occur particularly at the end. For example, part C in FIG. 3 is a part where a chilled structure is likely to occur. Therefore, when measuring a chilled structure, a chilled structure near the end may be determined.

  The electromagnetic induction sensor 10 includes an excitation coil 11 on the primary side that is excited by application of an alternating current to form a magnetic field, and an induction coil 12 on the secondary side that generates an electromotive force V by electromagnetic induction by excitation of the excitation coil 11. The exciting coil 11 and the induction coil 12 are coaxially wound to be integrally formed. In this case, the induction coil 12 is wound around the excitation coil 11. These coils can be realized by winding an insulation-coated wire around a long cylindrical object.

  The frequency f of the alternating current applied to the exciting coil 11 affects the penetration depth δ of the magnetic flux into the sample to be inspected, and also affects the electromotive force E generated in the sample to be inspected. In the case of this example, in order to inspect the casting part 1 around the electromagnetic induction sensor 10, the frequency f is lowered and the electromotive force E is increased at the same time to detect a subtle difference in the internal structure of the casting part 1 or the like. Is possible.

  In the electromagnetic induction sensor 10, the frequency f of the current applied to the excitation coil 11 is set to 10 kHz ≧ f ≧ 0.1 kHz depending on the type of casting part 1, the measurement range, and the like, and the number of turns N1 of the excitation coil 11 and the induction coil It is desirable that the 12 turns N2 have a relationship of 1000 ≧ N2 ≧ N1 ≧ 50. According to experimental results, the most ideal detection result is obtained when the current frequency f is 5 kHz (see FIG. 5 described later). Further, when the current frequency f is higher than 10 kHz, the measurement range is reduced, and the measurement accuracy may be lowered. When the current frequency f is lower than 0.1 kHz, the measurement accuracy may be lowered.

  The shape of the coil is not limited to a cylindrical shape. Further, the method for forming the coil is not limited to the method in which the induction coil 12 is directly wound around the exciting coil 11. For example, you may make it arrange | position coaxially, after forming the exciting coil 11 and the induction coil 12, respectively.

  The sensor holding means 20 is for holding the electromagnetic induction sensor 10 close to a predetermined distance from the surface of the casting part 1 as a measurement object. In addition, the shape of the sensor holding means 20 is not limited. For example, the sensor holding unit 20 may be configured by providing a mechanism that can move at a predetermined speed while holding the electromagnetic induction sensor 10.

  The AC power supply 30 includes a sine wave oscillator and a constant current amplifier, and the AC voltage of the angular frequency ω output from the sine wave oscillator becomes a constant current by the constant current amplifier and is supplied to the excitation coil 11 of the electromagnetic induction sensor 10. Is done.

  The detection circuit unit 40 receives the electromotive force V output from the induction coil 12 as an electric signal, and compares the detection circuit 41 to detect a change in the magnetic field. The detection circuit unit 40 determines the structure state of the casting part 1 based on the output of the comparison circuit 41. And a determination circuit 42 that performs the determination.

  In the comparison circuit 41, the output of the induction coil 12 by the casting part as the reference sample, that is, the reference value Vref is compared with the output measurement value Vout of the induction coil 12 by the casting part 1 as the sample to be inspected. Then, the amount of change in the measured value Vout with respect to the reference value Vref is detected separately as a phase change amount Δθ and an amplitude change amount ΔH, as shown in FIG. This phase change amount Δθ is an amount that depends on the magnetic characteristics of the casting part 1 as the specimen to be inspected, that is, the magnetic permeability, and the amplitude change amount ΔH is an amount that depends on the electrical characteristics of the casting part 1, that is, the electric conductivity. is there. Therefore, by distinguishing and detecting the magnetic characteristics and the electrical characteristics of the cast part 1, it is possible to detect subtle changes in the structural state of the cast part 1. That is, it is possible to detect a subtle difference in the internal structure of the cast part 1.

  In the determination circuit 42, it is determined whether or not the casting part 1 is in a steady state based on the output of the comparison circuit 41. If both the phase change amount Δθ and the amplitude change amount ΔH are zero, the casting part 1 is determined to be in a steady state. Further, if the above-described phase change amount Δθ and amplitude change amount ΔH are converted into data in association with the state of the cast part 1 in advance in the determination circuit 42, what is the state of the abnormality of the cast part 1, that is, the composition It is also possible to specifically identify and grasp the state of change, foreign matter or cracks.

  The recording unit 50 records a measurement state, a measurement result, and the like on a recording medium such as a recording sheet. The display unit 60 displays a measurement state, a measurement result, and the like. For example, the installation position of the electromagnetic induction sensor 10 is displayed or the measurement result is displayed. On the display unit 60, the measurement state, the measurement result, and the like can be displayed with graphics or numbers. The storage unit 70 stores the output of the electromagnetic induction sensor 10, the measurement state, the measurement result, and the like, and can read them out when necessary.

  Next, a cast part chilled structure evaluation method using the cast part chilled structure evaluation apparatus 100 will be described with reference to the drawings.

  When inspecting whether or not the cast part has a chilled structure, the cast part as a reference sample is measured in advance. The output of the induction coil 12 using a cast part as a reference sample is defined as a reference value Vref. Based on this, a threshold for determination is set.

  Next, the electromagnetic induction sensor 12 is brought close to the surface of the casting part 1 as the specimen to be inspected, and is inserted from the surface of the casting part 1 by the sensor holding means 20 in a state where it is inserted up to a predetermined position L at the end of the casting part 1, for example. It is installed close to a predetermined distance.

  In this state, when an alternating current is supplied to the exciting coil 11 of the electromagnetic induction sensor 10 and an alternating magnetic field is applied to the casting component 1, an induced electromotive force is generated in the induction coil 12 of the electromagnetic induction sensor 10. At this time, the induced electromotive force generated in the induction coil 12 of the electromagnetic induction sensor 10 changes according to the magnetic flux density of the AC magnetic field applied to the casting part 1, and the magnetic flux density of the AC magnetic field exists inside the casting part 1. Varies depending on the degree of chilled tissue.

  Therefore, a change amount of at least one of the amplitude and phase of the induced electromotive force generated in the induction coil 12 of the electromagnetic induction sensor 10 is detected, and the detected change amount is set based on a preset threshold value (based on the measurement result of the reference sample). Compared to stuff). Thereby, it can be accurately inspected whether or not the chilled structure exists inside the cast part 1. The measurement result is recorded in the recording unit 50 as necessary, displayed on the display unit 60, or stored in the storage unit 70.

  Further, by using the electromagnetic induction sensor 10 as a sensor for detecting whether or not a chilled structure is present in the cast part 1, it is estimated that a chilled structure of a cast part made of spheroidal graphite cast iron exists. Can do.

  FIG. 5 is a diagram illustrating an example of data measured by the cast part chilled structure evaluation apparatus 100. In the figure, 73U, 73V, 743, 744, and 745 are lot names of products used for measurement. There are 5 samples in each lot. In FIG. 5, the horizontal axis represents “LEVEL”, that is, changes in amplitude, and the vertical axis represents “FHASE”, that is, changes in phase. In this case, the frequency f of the current applied to the exciting coil was 5 kHz.

  As shown in FIG. 5, the electromagnetic induction sensor 10 is inserted into the casting part 1 and the FHASE signal is read. If the FHASE signal is between 50 and 200 (0.5V to 2.0V), it is acceptable and out of range (failed) ), The primary sorting can be easily performed by making it possible to visually check with a patrol lamp or the like.

  In this way, the amplitude and phase signal of a specific induced electromotive force is detected by the chemical composition and ferrite / pearlite ratio of each cast iron, and compared with the set threshold value (based on the measurement result of the reference sample). The chemical organization can be evaluated. In addition, these electromagnetic induction sensors can be appropriately designed and adopted according to the inspection or measurement of the shape, size (size), composition, structure, etc. of the casting part to be evaluated for nondestructive evaluation or evaluation conditions. .

  As described above, in the present embodiment, the cast component chilled structure evaluation apparatus 100 includes the electromagnetic induction sensor 10, the sensor holding means 20, the AC power supply 30, the detection circuit 40, the recording unit 50, and the display. A unit 60 and a storage unit 70 are included. The electromagnetic induction sensor 10 is formed by integrally forming an excitation coil 11 and an induction coil 12 coaxially. When inspecting whether or not the cast part 1 has a chilled structure, an alternating current is applied to the excitation coil 11 to generate a magnetic field. And the change of the magnetic field formed by the exciting coil by the coupling member 1 is detected by the induction coil 12, and for example, at least one of the amplitude and phase of the induced electromotive force generated in the induction coil is measured. Thus, the presence or absence of a chilled tissue is detected.

  As a result, the presence or absence of a chilled structure of a cast part, which has conventionally been impossible, can be accurately and easily obtained by nondestructive evaluation.

  Further, since the electromagnetic induction sensor 10 and the cast part 1 are not in contact with each other, the surface of the cast part (measured product) is smoothed for inspection as in the past, or the oxide film or coating film is removed. There is no need for pre-treatment, and cost and labor can be saved. In addition, the sensory test for determining the presence or absence of the chilled structure by removing the portion where the chilled structure is likely to occur is abolished, and the total number of cast parts can be inspected. Furthermore, since the distribution of the chilled structure of the cast part can be easily grasped by nondestructive evaluation, the inspection result can be easily reflected in the design, and the manufacturing method can be optimized. Therefore, it has the effect of reducing the weight and performance of cast parts.

  Further, the electromagnetic induction sensor 10 is inserted up to a predetermined position at the end of the casting part 1 and is placed close to a position at a predetermined distance from the surface of the casting part 1 by the sensor holding means 20, so that the electromagnetic induction of the casting part 1 is performed. The presence or absence of a chilled tissue can be detected with respect to the entire circumference of the insertion portion of the sensor 1, that is, the portion where the chilled tissue is likely to be generated can be measured in a lump, and the efficiency of measurement work can be improved.

  Further, the frequency f of the current applied to the exciting coil is set to 10 kHz ≧ f ≧ 0.1 kHz, and the number N1 of the exciting coil and the number N2 of the induction coil are set such that 1000 ≧ N2 ≧ N1 ≧ 50. Thus, the presence or absence of a chilled structure can be measured in a wider range.

  In the above-described embodiment, the electromagnetic induction sensor 10 is held close to a predetermined distance from the surface of the casting part 1 by the sensor holding means 20 in a state where the electromagnetic induction sensor 10 is inserted to the predetermined position L at the end of the casting part 1. Although the case where it installs was demonstrated, it is not limited to this. For example, as shown in FIGS. 6 and 7, the electromagnetic induction sensor 10 may be installed to be held close to a predetermined distance from the surface of the casting part 1 </ b> A outside the casting part 1 </ b> A. In this case, when measuring, the measurement may be performed while rotating the casting part 1A.

  FIG. 6 is a diagram illustrating another measurement example using the cast part chilled structure evaluation apparatus 100. FIG. 7 is a BB cross-sectional view of a portion where the electromagnetic induction sensor 10 of the cast part 1A is installed. As shown in FIG. 6, when evaluating a joint member for gas piping as a casting part 1A, the electromagnetic induction sensor 10 is held close to a predetermined distance from the surface of the casting part 1A outside the casting part 1A. It is designed to be installed. In this case, as shown in FIG. 7, the measurement is performed on the portion of the casting part 1A close to the tip of the electromagnetic induction sensor 10, and the other part is measured while rotating the casting part 1A or the electromagnetic induction sensor 10. Do. Such a measuring method is suitable for relatively large casting parts.

  Moreover, in the above-mentioned embodiment, although what performed the reference | standard setting using the casting component as a reference | standard sample previously was demonstrated, it is not limited to this. Measurement may be performed using a preset threshold value without using the reference sample.

  Further, in the above-described embodiment, the electromagnetic induction sensor 10 has been described as being held by the sensor holding means 20 in a state where the electromagnetic induction sensor 10 is inserted up to the predetermined position L at the end of the casting part 1, but is not limited thereto. Absent. For example, when a chilled structure is generated in the center depending on the type of casting part, an electromagnetic induction sensor may be inserted into the casting part for measurement. Alternatively, the electromagnetic induction sensor may be inserted into the casting part and measured while moving.

  Moreover, in the above-described embodiment, the reinforcing steel joint and the gas pipe joint are used as the casting parts, but the present invention is not limited to this. The present invention can be applied to all cast parts.

  The present invention can be applied mainly to chilled structure evaluation of casting parts such as gas pipes and reinforcing steel joint members, and can play a major role in improving the quality level of quality control of casting parts.

It is a figure which shows the structure of the chilled structure evaluation apparatus of the casting components of embodiment. 1 is a diagram illustrating a configuration of an electromagnetic induction sensor 10. FIG. It is an enlarged view of the part which installs the electromagnetic induction sensor 10 of the casting component 1. FIG. 3 is a model diagram of an electrical signal output from the electromagnetic induction sensor 10. FIG. It is a figure which shows an example of the data measured with the casting component chilled structure evaluation apparatus 100. FIG. It is a figure which shows the other example of a measurement using the casting component chilled structure evaluation apparatus. It is BB sectional drawing of the part which installs the electromagnetic induction sensor 10 of 1 A of casting components. It is a schematic diagram of the generation | occurrence | production state of a chilled structure | tissue.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Casting part 2 Support means 10 Electromagnetic induction sensor 11 Sine wave oscillator 12 Inductive coil 20 Sensor holding means 30 AC power supply 40 Detection circuit 41 Comparison circuit 42 Judgment circuit 50 Recording part 60 Display part 70 Storage part 100 Chilling of casting part Organization evaluation device

Claims (8)

  As a sensor for detecting the presence or absence of a chilled structure of a cast part, an excitation coil for applying an AC magnetic field to the cast part, and an induction coil for detecting the magnetic flux density of the AC magnetic field applied to the cast part from the excitation coil And measuring the amount of change of at least one of the amplitude and phase of the induced electromotive force generated in the induction coil due to the change of the alternating magnetic field by the casting part, and the chilled structure A method for evaluating a chilled structure of a cast part, characterized by detecting the presence or absence of a casting.   2. The casting part according to claim 1, wherein the electromagnetic induction sensor is inserted into the casting part to detect the presence or absence of a chilled structure with respect to the entire circumference of the electromagnetic induction sensor insertion portion of the casting part. Evaluation method of chilled structure.   The frequency f of the current applied to the exciting coil is set to 10 kHz ≧ f ≧ 0.1 kHz, and the number N1 of the exciting coil and the number N2 of the induction coil have a relationship of 1000 ≧ N2 ≧ N1 ≧ 50. The method for evaluating a chilled structure of a cast part according to claim 1 or 2.   The method for evaluating a chilled structure of a cast part according to any one of claims 1 to 3, wherein the cast part is a joint member for a gas pipe and a reinforcing bar. As a sensor for detecting the presence or absence of a chilled structure of a cast part, an excitation coil for applying an AC magnetic field to the cast part, and an induction coil for detecting the magnetic flux density of the AC magnetic field applied to the cast part from the excitation coil An electromagnetic induction sensor having
Sensor holding means for holding the electromagnetic induction sensor close to a predetermined distance from the surface of a casting part as a measurement object;
Judging means for judging the presence or absence of a chilled structure of the cast part based on the amount of change of at least one of the amplitude and phase of the induced electromotive force generated in the induction coil due to the change of the alternating magnetic field by the cast part; ,
An apparatus for evaluating a chilled structure of a cast part, comprising: output means for outputting a message to the effect that the determination means determines that there is a chilled structure of a cast part.   In the electromagnetic induction sensor, the frequency f of the current applied to the exciting coil is set to 10 kHz ≧ f ≧ 0.1 kHz, and the number N1 of the exciting coil and the number N2 of the induction coil are set to 1000 ≧ N2 ≧ N1 ≧ 50. 6. The cast part chilled structure evaluation apparatus according to claim 5, wherein the chilled structure evaluation apparatus is a relation.   The said holding | maintenance part hold | maintains the said electromagnetic induction sensor inserted in the inside of the said casting component on the center axis | shaft of the said casting component, when the said casting component is cylindrical shape. The cast structure evaluation apparatus for cast parts according to claim 6.   8. The cast part chilled structure evaluation apparatus according to claim 5, wherein the cast part is a joint member for a gas pipe and a reinforcing bar.

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