CN108072700A - A kind of steel ball ultrasonic detection method and device based on point focusing probe - Google Patents

Abstract

The invention discloses a steel ball ultrasonic flaw detection method and device based on a point focusing probe. The method includes: according to the actual focal length and refraction law of the point focusing probe in the steel ball to be detected, combined with the diameter specification of the steel ball to be detected, select The model of the point-focusing probe, the thickness of the water layer and the eccentric distance between the axis of the sound source of the point-focusing probe and the center of the steel ball to be detected; the ultrasonic instrument generates a high-frequency pulse signal, which excites the point-focusing probe to generate ultrasonic waves, and the ultrasonic waves pass through the coupling medium water to be detected Defect detection is carried out in the steel ball; the steel ball to be tested is fully expanded spherically within the effective detection area of the point focusing probe, and the point focusing probe receives the ultrasonic echo signal, and judges whether the steel ball to be tested has a defect according to the ultrasonic echo signal. The invention is simple in structure, convenient in operation, safe in use, strong in versatility, low in cost, high in detection accuracy, easy to realize automatic flaw detection of steel balls, and has great significance for ensuring the quality of steel balls and improving the reliability of bearings.

Description

A steel ball ultrasonic flaw detection method and device based on a point focusing probe

technical field

The invention relates to the fields of ultrasonic detection technology and steel ball non-destructive flaw detection technology, in particular to a steel ball ultrasonic flaw detection method and device based on a point focusing probe.

Background technique

As the core components of the machinery industry, bearings are widely used in all walks of life in the national economy, and ball bearings are the most widely used in all types of bearings. As the key part of the ball bearing, the quality of the steel ball has an important impact on the accuracy, transmission performance and service life of the ball bearing. When the steel ball is working under high-speed and heavy-load conditions, if there are quality problems such as tiny pores or cracks on the surface or inside, it is easy to cause the defects to grow and extend, and eventually lead to bearing failure. In severe cases, it will cause major safety accidents and endanger life and health and property safety.

At present, the vast majority of domestic enterprises still use the manual detection method to detect steel ball quality defects. This detection method not only requires a large amount of labor, but the efficiency is extremely low, and the detection quality is greatly affected by the workers' emotions, sense of responsibility and technical level, which can easily cause false detection and missed detection, and affect the product quality and production efficiency of the enterprise. , In addition, workers working under the condition of strong light source for a long time can easily cause damage to the eyes. Although many experts and scholars at home and abroad have successfully applied the machine vision method, photoelectric detection method and eddy current detection method to detect the defects of steel balls, these technologies can only detect the defects on the surface and near the surface of the steel balls, and the air holes in the steel balls , inclusions and other internal defects powerless.

Contents of the invention

The object of the present invention is to solve the problems mentioned above in the background technology section through a steel ball ultrasonic flaw detection method and device based on a point focusing probe.

For reaching this purpose, the present invention adopts following technical scheme:

A steel ball ultrasonic flaw detection method based on a point-focused probe, comprising the steps of:

S101. According to the actual focal length and refraction law of the point-focusing probe in the steel ball to be detected, combined with the diameter specifications of the steel ball to be detected, select the model of the point-focusing probe, the thickness of the water layer, and the axis of the sound source of the point-focusing probe and the steel ball to be detected. The eccentricity of the center of the ball;

S102, the ultrasonic instrument generates a high-frequency pulse signal, the excitation point focusing probe generates ultrasonic waves, and the ultrasonic waves enter the steel ball to be detected through the coupling medium water for defect detection;

S103 , the steel ball to be detected is fully expanded spherically within the effective detection area of the point-focused probe, and the point-focused probe receives ultrasonic echo signals, and judges whether the steel ball to be detected has defects according to the ultrasonic echo signals.

In particular, the step S101 includes: adjusting the position of the point-focusing probe so that the axis of the sound source is collinear with the center of the steel ball to be detected, so as to realize the internal defect detection of the steel ball to be detected.

In particular, the step S101 includes: according to the actual focal length of the ultrasonic waves emitted by the point-focus probe in the steel ball to be detected, select the model of the point-focus probe and the thickness of the water layer, and adjust the actual focus area of the point-focus probe to the bottom of the steel ball, Wherein, the model of the point focusing probe includes wafer diameter and focal length.

In particular, the step S101 includes: adjusting the position of the point-focusing probe according to the refraction law and Snell's law of the ultrasonic waves emitted by the point-focusing probe at the interface between substances, so that the axis of the sound source deviates from the center of the steel ball to be detected to reach Set the distance so that the ultrasonic wave entering the steel ball to be detected is converted into a transverse wave, and the surface defect detection of the steel ball to be detected is realized.

In particular, the type of the point focusing probe used to detect the surface defect of the steel ball to be tested is the same as that used for the detection of the internal defect of the steel ball to be tested, but the relative position of the setting of the steel ball to be tested is different.

In particular, the step S103 specifically includes: the steel ball to be detected is fully expanded spherically within the effective detection area of the point focusing probe, the point focusing probe receives the ultrasonic echo signal and converts it into a voltage signal and outputs it to the ultrasonic instrument, and the ultrasonic The instrument performs data processing including amplification, filtering and A/D conversion on the received voltage signal, extracts the signal characteristics and presents them on the display in the form of waveform graphics, and judges whether the steel ball to be detected is Flawed.

The invention also discloses a steel ball ultrasonic flaw detection device for realizing the above-mentioned steel ball ultrasonic flaw detection method. and a display; the steel ball unfolding mechanism is used to fully expand the surface of the steel ball to be detected within the effective detection area range of the first point focusing probe and the second point focusing probe; the probe adjustment bracket is used to install the first Point focusing probe, the second point focusing probe, adjust the relative position of the first point focusing probe, the second point focusing probe and the steel ball center to be detected; the first point focusing probe, the second point focusing probe and the electric Connected, set in the water tank; the water tank is filled with coupling medium water; the ultrasonic instrument is electrically connected with the display, used to generate high-frequency pulse signals, and excite the first point focusing probe and the second point focusing probe to emit ultrasonic waves , the ultrasonic wave enters the steel ball to be detected through the coupling medium water for defect detection. The first point focusing probe and the second point focusing probe receive the ultrasonic echo signal and convert it into a voltage signal and output it to the ultrasonic instrument. The signal undergoes data processing including amplification, filtering, and A/D conversion, and the extracted signal features are presented on the display in the form of waveform graphics, and it is judged according to the waveform graphics whether there is a defect in the steel ball to be detected.

The steel ball ultrasonic flaw detection method and device based on the point focusing probe proposed by the present invention can not only detect the surface defect of the steel ball, but also detect the internal defect of the steel ball, and make up for the blind spot of the steel ball flaw detection in the prior art. In the present invention, by analyzing the actual focal length of the point-focusing probe in the steel ball and selecting the parameters of the point-focusing probe and the thickness of the water layer, the sensitivity of ultrasonic waves to internal defects of the steel ball is effectively improved, and the signal-to-noise ratio of defect echoes is improved. The invention can detect the defects of steel balls with different diameters and specifications, and has strong versatility and interchangeability. The steel ball ultrasonic flaw detection device based on the point focusing probe provided by the present invention is simple in structure, easy to operate, safe to use, strong in versatility, low in cost, high in detection accuracy, and easy to realize automatic flaw detection of steel balls, which is very important for ensuring the quality of steel balls and improving the quality of bearings. Reliability, etc. are of great significance, suitable for popularization and application, and have broad market application prospects.

Description of drawings

Fig. 1 is a structural schematic diagram of a steel ball ultrasonic flaw detection device based on a point focusing probe provided by the present invention;

Fig. 2 is the schematic diagram of the principle of detecting the internal defect of the steel ball by the point focusing probe provided by the present invention;

Fig. 3 is the schematic diagram of the transmission path and focusing situation of the ultrasonic waves emitted by the point focusing probe provided by the present invention in the steel ball;

Fig. 4A is a schematic diagram of steel ball flat-bottomed hole defects provided by the present invention; Fig. 4B to Fig. 4F are schematic diagrams of echo signals of steel ball flat-bottomed hole defects of different depths provided by the present invention;

Fig. 5 is the schematic diagram of the principle of the law of ultrasonic refraction provided by the present invention;

6A1 to 6A8 are schematic diagrams of echo signals of various surface defects of steel balls provided by the present invention.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be intervening elements at the same time. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Please refer to FIG. 1 , which is a structural schematic diagram of a steel ball ultrasonic flaw detection device based on a point focusing probe provided by the present invention.

In this embodiment, the steel ball ultrasonic flaw detection device based on the point focusing probe specifically includes: a steel ball expansion mechanism 2, a first point focusing probe 3, a second point focusing probe 3', a probe adjustment bracket 4, a water tank 5, an ultrasonic instrument 6 and monitor7. The steel ball unfolding mechanism 2 is used to fully expand the surface of the steel ball 1 to be detected within the effective detection area range of the first point focusing probe 3 and the second point focusing probe 3'. The probe adjustment bracket 4 is used to install the first point focusing probe 3 and the second point focusing probe 3', and adjust the relative position of the first point focusing probe 3, the second point focusing probe 3' and the center of the steel ball 1 to be detected . The first point-focusing probe 3 and the second point-focusing probe 3' are electrically connected to the ultrasonic instrument 6, and are arranged in the water tank 5. The coupling medium water 8 is contained in the water tank 5 . The ultrasonic instrument 6 is electrically connected with the display 7, and is used to generate a high-frequency pulse signal to excite the first point focusing probe 3 and the second point focusing probe 3' to emit ultrasonic waves, and the ultrasonic waves enter the steel ball 1 to be detected through the coupling medium water 8 for further processing. Defect detection, the first point focusing probe 3 and the second point focusing probe 3' receive the ultrasonic echo signal and convert it into a voltage signal and output it to the ultrasonic instrument 6, and the ultrasonic instrument 6 includes amplification, filtering, Data processing including A/D conversion extracts signal features and presents them on the display 7 in the form of waveform graphics, and judges whether the steel ball 1 to be detected has defects according to the waveform graphics.

Based on the above-mentioned device for implementing ultrasonic flaw detection of steel balls, this embodiment discloses a method for ultrasonic flaw detection of steel balls based on a point-focused probe. The method includes the following steps:

S101. According to the actual focal length and refraction law of the point focusing probe (3, 3') inside the steel ball 1 to be detected, and in combination with the diameter specification of the steel ball 1 to be detected, select the model of the point focusing probe (3, 3'), The thickness of the water layer and the eccentric distance between the axis of the sound source of the point focusing probe (3, 3') and the center of the steel ball 1 to be detected.

S102, the ultrasonic instrument 6 generates a high-frequency pulse signal, and the point-focusing probe (3, 3') is excited to generate ultrasonic waves, and the ultrasonic waves enter the steel ball 1 to be detected through the coupling medium water 8 for defect detection.

S103, the steel ball 1 to be detected is fully expanded spherically within the effective detection area of the point focusing probe (3, 3'), and the point focusing probe (3, 3') receives the ultrasonic echo signal, according to the ultrasonic echo signal It is judged whether there is a defect in the steel ball 1 to be detected. In this embodiment, the point focus probe (3, 3') receives the ultrasonic echo signal and converts it into a voltage signal and outputs it to the ultrasonic instrument 6, and the ultrasonic instrument 6 includes amplification, filtering, and A/D for the received voltage signal. The data processing including the conversion extracts the signal features and presents them on the display 7 in the form of waveform graphics, and judges whether the steel ball 1 to be detected has defects according to the waveform graphics.

Specifically, when detecting the internal defects of the steel ball 1 to be detected, the position of the first point focusing probe 3 is adjusted so that the axis of the sound source is collinear with the center of the steel ball 1 to be detected, and the accuracy of the steel ball 1 to be detected is realized. Internal defect detection. As shown in FIG. 2 , FIG. 2 is a schematic diagram of the principle of detecting internal defects of a steel ball by a point focusing probe provided by the present invention. Combined with the sound pressure distribution formula on the axis of the sound source:

P＝2P ₀ sin[π/2*B(1-X/F)]/(1-X/F)

Among them, P ₀ refers to the initial sound pressure of the sound source; F refers to the focal length; X refers to the distance from the measurement point to the axis of the sound source; B refers to the parameters related to the sharpness of the focus. It can be known that the position of the first point focusing probe 3 is adjusted so that the axis of the sound source is collinear with the center of the steel ball 1 to be detected. When the source is on the axis, the echo signal representing the defect 9 can be found before the bottom wave signal of the steel ball 1 to be detected. It is easy for those skilled in the art to understand: within the focus area of the first point focus probe 3, the detection sensitivity and signal-to-noise ratio are significantly higher than those of the non-focus probe, but outside the focus area, the detection sensitivity drops rapidly, and the detection effect Possibly even inferior to unfocused probes. Therefore, it is very necessary to analyze the actual focal length of the first point focusing probe 3 in the steel ball 1 to be tested to find out the actual focusing area.

According to the actual focal length of the ultrasonic waves emitted by the first point focusing probe 3 in the steel ball 1 to be tested, select the model of the first point focusing probe 3 and the thickness of the water layer, and adjust the actual focus area of the first point focusing probe 3 to the bottom of the steel ball , so as to improve the sensitivity of ultrasonic waves to internal defects of steel balls and improve the signal-to-noise ratio of defect echoes. Wherein, the model of the first point focusing probe 3 includes the wafer diameter and focal length. As shown in Figure 3, Figure 3 is a schematic diagram of the propagation path and focusing situation in the steel ball of the ultrasonic waves emitted by the point-focusing probe provided by the present invention, and F' is the actual focus of the first point-focusing probe 3 in the steel ball among the figures, F is the focal point of the first point focusing probe 3, a represents the thickness of the water layer, b represents the distance between the actual focal point F' and the steel ball surface, c represents the distance between the actual focal point F' and the focal point F, and d represents the distance between the focal point F' and the steel ball The distance between the center of the sphere, f represents the focal length, f' represents the actual focal length, R is the radius of curvature of the steel ball, and D represents the diameter of the first point focusing probe 3 chip.

Combined with the analysis of ultrasonic refraction law, the expression formula of the actual focal length can be obtained:

f'=f+dk/[(dC _work /RC _coupling ) sin ² γ-k], where

d=f-a-R, sinγ=D/2f.

This can be based on the expression formula of the above-mentioned actual focal length f' to select a reasonable first point focusing probe model 3 (chip diameter and focal length) and water layer thickness, and adjust the actual focusing area to the position at the bottom of the steel ball 1 to be detected, thereby improving the ultrasonic Sensitivity to internal defects of steel balls and improved signal-to-noise ratio of defect signals.

In the field of non-destructive testing, flat-bottomed holes are generally artificial standard defect patterns of internal defects in metals. Figure 4A is a schematic diagram of steel ball flat-bottomed hole defects, in which D represents the diameter of the steel ball, d represents the diameter of the flat-bottomed hole defect, and h represents the depth of the flat-bottomed hole defect; Fig. 4B to Fig. Wave signal schematic diagram; Waveform diagram shown in Fig. 4B to Fig. 4F is on the implementation device shown in Fig. 1, detects the flat-bottomed hole defect of the diameter φ0.5mm of different depths in the diameter φ54mm steel ball with the above-mentioned detection method that the present invention provides The obtained signal waveform diagram, the circled part of the waveform diagram in the figure is the waveform of the defect position. The model selected for the first point focusing probe 3 in the detection process is: the diameter of the wafer is 10mm, the focal length is 59.4mm, and the thickness of the water layer is 19.5mm. Analysis of the detection signal in the figure shows that the echo signal of the flat-bottomed hole defect is found before the bottom wave signal of the steel ball 1 to be detected, and the sound path difference between the defect signal and the bottom wave signal is basically consistent with the depth value of the flat-bottomed hole. It can be deduced that: when the sound source axis of the first point focusing probe 3 is collinear with the center of the steel ball 1 to be detected, the actual focus area can be adjusted by selecting reasonable probe parameters (chip diameter and focal length) and water layer thickness. To the bottom of the steel ball 1 to be detected, if the internal defect of the steel ball 1 to be detected is located on the sound source axis of the probe, the defect echo signal with a better signal-to-noise ratio can be found before the bottom wave signal of the steel ball 1 to be detected .

According to the law of refraction and Snell's law of the ultrasonic waves emitted by the second point focusing probe 3' at the interface between substances, the position of the second point focusing probe 3' is adjusted so that the axis of the sound source deviates from the center of the steel ball 1 to be detected. The distance is set so that the ultrasonic waves entering the steel ball 1 to be detected are converted into transverse waves, so as to realize the detection of surface defects of the steel ball 1 to be detected. As shown in Figure 5, Figure 5 is a schematic diagram of the principle of the ultrasonic refraction law provided by the present invention, in which α represents the ultrasonic incident angle, α _s ' represents the shear wave reflection angle, α _L ' represents the longitudinal wave reflection angle, and β _s represents the shear wave refraction angle , β _L represents the longitudinal wave refraction angle. According to the refraction law and Snell's law of ultrasonic waves at the liquid-solid interface (i.e., the interface with matter), adjust the eccentric distance between the sound source axis of the second point focusing probe 3' and the center of the steel ball 1 to be detected, so that the first The longitudinal wave emitted by the two-point focusing probe 3' is converted into a transverse wave at the interface and enters the steel ball 1 to be detected, thereby realizing the detection of surface defects of the steel ball 1 to be detected.

As shown in Figures 6A1 to 6A8, Figures 6A1 to 6A8 are schematic diagrams of echo signals of various surface defects of steel balls provided by the present invention, and the circled parts in the figures are waveform diagrams of the positions of steel ball defects; among them, Figure 6A1 is a waveform diagram without pit defects, Figure 6A2 is an echo signal waveform diagram with pit defects; Figure 6A3 is a waveform diagram without cluster point defects, and Figure 6A4 is an echo signal waveform diagram with cluster point defects; Figure 6A5 is a waveform diagram without scratch defects, Figure 6A6 is an echo signal waveform diagram with scratch defects; Figure 6A7 is a waveform diagram without dot defects, and Figure 6A8 is an echo signal waveform diagram with dot defects. The waveform diagrams shown in Fig. 6A1 to Fig. 6A8 are signal waveform diagrams obtained by using the above-mentioned detection method provided by the present invention to detect common surface defects in steel balls with a diameter of φ54mm on the implementation device shown in Fig. 1, the second point in the detection process The focus probe 3' is consistent with the probe type and water layer thickness of the first point focus probe 3, and the eccentric distance between the sound source axis of the second point focus probe 3' and the center of the steel ball 1 to be detected is 3 mm. It can be seen from the analysis of the detected signals that the detection method provided by the present invention can better detect defects such as pits, group spots, scratches, and dots that occur during the processing of steel balls.

The steel ball ultrasonic flaw detection method based on point focusing probes (3, 3') provided by the present invention is based on the principle that ultrasonic waves will reflect when encountering defects when propagating in a solid, and the reflected waves are received by the probe and then converted into electrical signals. After being amplified, filtered and A/D converted by the receiving circuit, the echo signal that can represent the defect is displayed on the computer data processing system. The principle of detecting the internal defect of the steel ball 1 to be detected in the present invention is: the sound pressure on the axis of the sound source of the first point focusing probe 3 is the strongest, when the internal defect of the steel ball 1 to be detected is on the axis of the sound source, not only can The defect echo with good signal-to-noise ratio is obtained, and the sensitivity to internal defects is also increased. The principle of detecting the surface defects of the steel ball 1 to be detected in the present invention is: by changing the incident angle of the ultrasonic wave emitted by the second point focusing probe 3', it is converted into a transverse wave after entering the steel ball 1 to be detected, and the transverse wave is converted into a transverse wave of the steel ball to be detected 1 Surface defects are more sensitive.

The technical scheme of the present invention can not only detect the surface defect of the steel ball 1 to be detected, but also detect the internal defect of the steel ball 1 to be detected, so as to make up for the blind spot of flaw detection of the steel ball in the prior art. In the present invention, by analyzing the actual focal length of the point-focusing probe (3, 3') in the steel ball 1 to be detected, the parameters of the point-focusing probe (3, 3') and the thickness of the water layer are selected, which effectively improves the impact of ultrasonic waves on the internal defects of the steel ball. sensitivity and improve the signal-to-noise ratio of defect echoes. The invention can detect the defects of steel balls with different diameters and specifications, and has strong versatility and interchangeability. The steel ball ultrasonic flaw detection device based on the point focusing probe provided by the present invention is simple in structure, easy to operate, safe to use, strong in versatility, low in cost, high in detection accuracy, and easy to realize automatic flaw detection of steel balls, which is very important for ensuring the quality of steel balls and improving the quality of bearings. Reliability, etc. are of great significance, suitable for popularization and application, and have broad market application prospects.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (7)

1. a kind of steel ball ultrasonic detection method based on point focusing probe, which is characterized in that include the following steps：

S101, according to point focusing probe in the in vivo real focal length of steel ball ball to be detected and the law of refraction, with reference to steel ball to be detected Diameter specifications, select model, water layer thickness and the point focusing probe sound source axis of point focusing probe and steel ball ball to be detected The eccentricity of the heart；

S102, Ultrasound Instrument generate high-frequency pulse signal, excitation point focusing probe generate ultrasonic wave, the coupled WATER AS FLOW MEDIUM of ultrasonic wave into Enter and defects detection is carried out in steel ball to be detected；

S103, steel ball to be detected carry out spherical surface in the range of effective detection zone of point focusing probe to be unfolded entirely, point focusing probe Ultrasound echo signal is received, judges that the steel ball to be detected whether there is defect according to the ultrasound echo signal.

2. the steel ball ultrasonic detection method according to claim 1 based on point focusing probe, which is characterized in that the step S101 includes：The position of point focusing probe is adjusted, makes its sound source axis conllinear with the centre of sphere of steel ball to be detected, realizes to be detected The Inner Defect Testing of steel ball.

3. the steel ball ultrasonic detection method according to claim 2 based on point focusing probe, which is characterized in that the step S101 includes：The ultrasonic wave emitted according to point focusing probe real focal length in steel ball to be detected selects the type of point focusing probe Number and water layer thickness, the actual focal zone of point focusing probe is adjusted to steel ball bottom, wherein, the type of the point focusing probe Number include wafer diameter and focal length.

4. the steel ball ultrasonic detection method according to claim 3 based on point focusing probe, which is characterized in that the step S101 includes：The law of refraction and Snell's law at matter interface are being handed over according to the ultrasonic wave that point focusing probe emits, point of adjustment is gathered The position of coke probe, makes the centre of sphere of its sound source axis runout steel ball to be detected reach setpoint distance, makes into steel ball to be detected Ultrasonic wave be converted to shear wave, realize the surface defects detection to steel ball to be detected.

5. the steel ball ultrasonic detection method according to claim 4 based on point focusing probe, which is characterized in that for be checked Survey the model of the point focusing probe and the point focusing probe for steel ball Inner Defect Testing to be detected of steel ball surface defect detection It is identical but different from the relative position of the setting of steel ball to be detected.

6. the steel ball ultrasonic detection method based on point focusing probe according to one of claim 1 to 5, which is characterized in that The step S103 is specifically included：Steel ball to be detected carries out spherical surface in the range of effective detection zone of point focusing probe and opens up entirely It opens, point focusing probe receives ultrasound echo signal and be converted into voltage signal and export to Ultrasound Instrument, and Ultrasound Instrument is to receiving Voltage signal carries out the data processing including amplification, filtering, A/D conversions, extracts the side of signal characteristic waveform graph Formula is presented over the display, judges that the steel ball to be detected whether there is defect according to the waveform graph.

7. a kind of steel ball reflectoscope based on point focusing probe, which is characterized in that the device includes：Steel ball unwinder Structure, the first point focusing probe, the second point focusing probe, probe adjusting bracket, water tank, Ultrasound Instrument and display；The steel ball Unfolding mechanism be used for by the surface of steel ball to be detected the first point focusing probe, the second point focusing probe effective detection zone model It encloses and interior is unfolded entirely；The probe adjusting bracket adjusts first for installing the first point focusing probe, the second point focusing probe Point focusing probe, the second point focusing probe and the relative position of the steel ball centre of sphere to be detected；First point focusing probe, second point Focusing probe is electrically connected with Ultrasound Instrument, is arranged in the water tank；Couplant water is held in the water tank；The Ultrasound Instrument with Display is electrically connected, for generating high-frequency pulse signal, the first point focusing probe of excitation, the second point focusing probe transmitting ultrasound Ripple, ultrasonic wave carry out defects detection by couplant water into steel ball to be detected, and the first point focusing probe, the second point focusing are visited Head receives ultrasound echo signal and is converted into voltage signal and exports to Ultrasound Instrument, and Ultrasound Instrument carries out the voltage signal received Including amplifying, filtering, the data processing including A/D conversions, extract signal characteristic and be presented on display with the mode of waveform graph On device, judge that the steel ball to be detected whether there is defect according to the waveform graph.