Anti-touch eddy current detection method for precision part

Abstract

The invention relates to the technical field of non-contact eddy current detection, in particular to an anti-touch eddy current detection method for a precision part. A plurality of airflow channels are arranged on the periphery of the shell of the eddy current detection sensor, an air pump is adopted to convey airflow into the airflow channels during detection, and the distance between the sensor and a workpiece to be detected is adjusted by adjusting the air pressure, so that a stable air floating layer is formed between the eddy current detection sensor and the surface of the workpiece to be detected. The pneumatic principle is utilized, it is guaranteed that the sensor and the workpiece to be detected do not touch during dynamic detection, abrasion and influence caused by direct contact between the sensor and the workpiece to be detected are avoided, the detection precision is improved, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of non-contact eddy current detection, and in particular to an anti-contact eddy current detection method for precision components. Background Art

[0002] In the manufacturing field, there are many parts made of rare metal materials. In order to ensure the quality of metal components, non-contact non-destructive testing is required for the parts after manufacturing. Due to the high detection requirements, surface and near-surface micro-defects can be found as much as possible. Looking at the existing non-destructive testing methods, only the eddy current method can do it. However, in order to ensure the detection sensitivity, the eddy current method must use a detection frequency of several megahertz to meet the requirements. Due to the existence of the skin effect, the distance between the sensor and the measured surface is very small, generally less than 1mm. In theory, the smaller the gap between the sensor and the workpiece, the better, and the distance must be kept constant, otherwise it will cause fluctuations in sensitivity.

[0003] The existing detection method is to add a gap measurement sensor in front of the eddy current sensor or the eddy current detection sensor directly gives an absolute lift-off signal to provide it to the mechanical drive actuator to ensure that it does not touch the workpiece surface. Since the parts are usually non-standard products, there are certain tolerances in manufacturing. Therefore, this traditional actuator, when the detection efficiency is required, often produces a situation where the sensor cannot respond in time, causing the workpiece surface to be touched or even scratched. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an anti-touch eddy current detection method for precision parts, which is implemented as follows:

[0005] An anti-touch eddy current detection method for precision parts is used for non-contact detection of tiny defects on the surface and near the surface of special metal materials. The specific steps include:

[0006] 1) Eddy current detection sensor design: including sensor housing, eddy current detection coil assembly and air flotation assembly;

[0007] The eddy current detection sensor housing comprises an inner housing and an outer housing which are sleeved with each other, a plurality of air flow channels are formed between the inner housing and the outer housing, a detection port is provided on the lower end surface of the inner housing, and an air outlet of the air flow channel is flush with the detection port;

[0008] The eddy current detection coil assembly is arranged at the detection port of the inner shell;

[0009] The air flotation assembly is arranged at the upper end of the outer shell, and comprises a micro air pump, a multi-vent valve and an air inlet joint which are connected in sequence, and the air inlet joint is connected to the air inlet of the air flow channel;

[0010] 2) Non-contact eddy current detection: The micro air pump transmits gas with a certain air pressure into the air flow channel and forms an air floating layer on the surface of the eddy current detection sensor, so that the eddy current detection sensor is suspended on the surface of the workpiece to be tested and maintains a fixed distance from it; the eddy current detection signal of the surface of the workpiece to be tested is obtained through the eddy current detection coil assembly.

[0011] Furthermore, the step 2) also includes an automatic distance adjustment function, which realizes automatic adjustment of the distance between the eddy current detection sensor and the surface of the workpiece to be measured by applying airflows of different pressure values ​​in the airflow channel.

[0012] Furthermore, the eddy current detection sensor is a high-frequency eddy current detection sensor, and its detection frequency range is 1 MHz to 30 MHz, which can effectively detect micro cracks.

[0013] Compared with the existing technology, this application can obtain the following technical effects:

[0014] The present invention sets a plurality of air flow channels on the outer periphery of the eddy current detection sensor housing, and uses an air pump to convey air flow in the air flow channels during detection, so that the air pressure is kept constant, so that the eddy current detection sensor and the surface of the workpiece to be detected form an air floating layer whose gap can be quickly and automatically adjusted. In this way, the distance between the workpiece and the sensor can be adjusted by adjusting the air pressure. At the same time, the pneumatic principle is also used to ensure that there is no contact between the two during dynamic detection. The present invention achieves the effects of fast distance adjustment speed, high detection efficiency, high detection sensitivity, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the examples of the present invention or the technical solutions in the prior art or the drawings required for use in the description of the prior art, a brief introduction is given. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 Schematic diagram of the eddy current detection sensor and the workpiece to be tested.

[0017] Figure 2 This is a partial structural schematic diagram of an eddy current detection sensor.

[0018] In the figure:

[0019] 10- clamping mechanism;

[0020] 20-Metal workpiece to be tested;

[0021] 30 - eddy current detection sensor, 31 - inner shell, 32 - outer shell, 33 - air flow channel, 34 - detection coil, 35 - air floating layer. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but only represents selected embodiments of the present invention.

[0023] In the manufacturing field, the quality inspection of its parts, especially some parts made of special metals, has very strict inspection requirements and often requires non-contact inspection. In order to meet its inspection needs, eddy current inspection has become an ideal non-destructive inspection method. However, maintaining precise spacing is crucial to the sensitivity of eddy current sensors, especially in high-frequency detection.

[0024] Embodiment 1:

[0025] In order to solve the problems of insufficient follow-up and sensor touching the workpiece caused by traditional actuators, the present invention discloses an anti-touch eddy current detection method for precision parts, which is used for non-contact detection of tiny defects on the surface and near the surface of special metal materials. The specific steps include:

[0026] 1) Eddy current detection sensor design: including sensor housing, eddy current detection coil assembly and air flotation assembly.

[0027] Reference Figure 1-2 , an automated mechanical clamping mechanism 10 is used to clamp the eddy current detection sensor 30. The sensor housing includes an inner housing 31 and an outer housing 32 which are mutually nested. A plurality of airflow channels 33 are formed between the inner housing 31 and the outer housing 32. The lower end surface of the inner housing 31 has a detection port, and the air outlet of the airflow channel 33 is flush with the detection port. The inner and outer housings are both made of lightweight materials, such as aluminum alloy materials, to reduce the overall weight of the sensor and provide good mechanical protection. Multiple airflow channels are designed between the inner and outer housings to promote effective gas transportation and ensure the air flotation effect. The air outlet of the airflow channel is flush with the detection port to ensure that the airflow can flow out freely and form a stable air flotation layer 35.

[0028] The eddy current detection coil assembly is arranged at the detection port of the inner shell; the eddy current detection coil assembly is made of highly conductive material and can be wound into a planar spiral detection coil 34 in a circular, elliptical, racetrack, square or other shape.

[0029] The flotation component is arranged at the upper end of the outer shell, and includes a micro air pump, a multi-vent valve and an air inlet connector which are connected in sequence, and the air inlet connector is connected to the air inlet of the air flow channel; a high-efficiency micro air pump is selected to output adjustable air pressure to meet the flotation requirements of different workpiece surfaces; the multi-vent valve is used to adjust the flow rate of the air flow to ensure uniform gas distribution and can be flexibly adjusted according to detection requirements; the air inlet connector is connected to the air inlet of the air flow channel to ensure that the gas can flow in and out smoothly.

[0030] 2) Non-contact eddy current detection: The micro air pump transmits gas with a certain air pressure into the air flow channel and forms an air floating layer on the surface of the eddy current detection sensor, so that the eddy current detection sensor is suspended on the surface of the metal workpiece 20 to be tested and maintains a fixed distance therefrom; the eddy current detection signal of the surface of the workpiece to be tested is obtained through the eddy current detection coil assembly. The pneumatic principle is used to ensure that the eddy current detection sensor maintains a fixed distance from the workpiece surface during dynamic detection, avoiding wear and influence caused by direct contact, thereby improving detection accuracy and equipment life.

[0031] Embodiment 2:

[0032] On the basis of Example 1, the sensor housing of the eddy current detection sensor 30 designed in step 1) is designed with another implementation structure, wherein the sensor housing comprises an inner housing and an outer housing which are nested with each other, a complete airflow cavity is formed between the inner housing and the outer housing, the lower end face of the inner housing has a detection port, and the eddy current detection coil assembly is arranged at the detection port; a plurality of air outlets which can connect the airflow cavity with the outside of the housing are arranged in an array on the surface of the outer housing corresponding to the detection port, so as to ensure that the airflow can flow out freely and form a stable air floating layer.

[0033] Embodiment three:

[0034] Furthermore, the step 2) also includes an automatic distance adjustment function, which realizes automatic adjustment of the distance between the eddy current detection sensor and the surface of the workpiece to be measured by applying airflows of different pressure values ​​in the airflow channel.

[0035] In this embodiment, the application of different air pressure values ​​during automatic distance adjustment is performed by establishing a mathematical model between the air floating structure, load and buoyancy, analyzing the current air floating state and actual distance, and then performing air pressure compensation.

[0036] Specifically, real-time air flotation data is obtained by setting up an air flotation sensor component, and the distance is calculated and judged through a pre-established air flotation-distance measurement model. When the actual distance is smaller than the set distance, the corresponding compensation air pressure is applied. When the actual distance is larger than the set distance, the applied air pressure value is reduced accordingly.

[0037] The air flotation sensor assembly includes a plurality of micro buoyancy monitoring sensors, which are respectively embedded at the openings of the airflow channel, and each micro buoyancy monitoring sensor corresponds to an opening of the airflow channel.

[0038] Furthermore, the eddy current detection sensor is a high-frequency eddy current detection sensor. The high-frequency eddy current detection sensor has a detection frequency range of 1MHz to 30MHz, which can effectively detect micro cracks to adapt to different materials and detection requirements. The high-frequency eddy current detection sensor has high sensitivity and can monitor tiny defects on the surface of the workpiece to be tested.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A non-contact eddy current detection method for precision parts, used for non-contact detection of tiny defects on the surface and near the surface of special metal materials, characterized in that: The specific steps include: 1) Eddy current detection sensor design: including sensor housing, eddy current detection coil assembly and air flotation assembly; The eddy current detection sensor housing comprises an inner housing and an outer housing which are sleeved with each other, a plurality of air flow channels are formed between the inner housing and the outer housing, a detection port is provided on the lower end surface of the inner housing, and an air outlet of the air flow channel is flush with the detection port; The eddy current detection coil assembly is arranged at the detection port of the inner shell; The air flotation assembly is arranged at the upper end of the outer shell, and comprises a micro air pump, a multi-vent valve and an air inlet joint which are connected in sequence, and the air inlet joint is connected to the air inlet of the air flow channel; 2) Non-contact eddy current detection: The micro air pump transmits gas with a certain air pressure into the air flow channel and forms an air floating layer on the surface of the eddy current detection sensor, so that the eddy current detection sensor is suspended on the surface of the workpiece to be tested and maintains a fixed distance from it; the eddy current detection signal of the surface of the workpiece to be tested is obtained through the eddy current detection coil assembly.

2. The anti-touch eddy current detection method for precision parts according to claim 1, characterized in that: The step 2) also includes an automatic distance adjustment function, which realizes automatic adjustment of the distance between the eddy current detection sensor and the surface of the workpiece to be measured by applying airflows of different pressure values ​​in the airflow channel.

3. The anti-touch eddy current detection method for precision parts according to claim 1, characterized in that: The eddy current detection sensor is a high-frequency eddy current detection sensor, and its detection frequency range is 1 MHz to 30 MHz, which can effectively detect micro cracks.

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