A micromagnetic sensor for synchronous detection of crankshaft journals and transition fillets

Abstract

The present invention discloses a micro-magnetic sensor for synchronous detection of crankshaft journals and transition fillets. The end of the magnetic core of the adopted U-shaped electromagnet is processed into an inner tangent surface, and the inner tangent surface contacts the journal surface to form a magnetic circuit. The alternating magnetic field provided by the U-shaped electromagnet is mainly distributed along the circumference of the journal to magnetize the journal surface material, and also partially passes through the transition fillet area to return to the main magnetic circuit. The passing magnetic field can magnetize the material in the transition fillet area. Two sets of independent detection elements are configured inside the U-shaped electromagnet to pick up multiple types of micro-magnetic signals (magnetic Barkhausen noise, tangential magnetic field intensity, incremental magnetic permeability and multi-frequency eddy current) on the journal surface and the fillet respectively. The sensor disclosed by the present invention can perform synchronous micro-magnetic detection on the crankshaft journal and transition fillet, and is used for non-destructive evaluation of the microstructure and residual stress uniformity of the crankshaft journal and transition fillet area.

Description

Technical Field

[0001] The present invention relates to a micromagnetic sensor for synchronous detection of crankshaft journals and transition fillets, belongs to the technical field of non-destructive testing, and aims to provide a sensor solution for detecting uniformity of mechanical properties of crankshaft surfaces. Background Art

[0002] Micromagnetic technology has the potential to perform non-destructive testing of the surface mechanical properties of ferromagnetic parts. The micromagnetic sensors currently developed are mainly for flat plates or parts with a large radius of curvature. There are few reports on special micromagnetic sensors for crankshafts with complex shapes. The patent (CN202110416558.8) discloses a surface detection micromagnetic sensor based on a conformal sliding shoe, which can perform micromagnetic detection on crankshaft fillets, but cannot be applied to journal detection. In order to achieve synchronous micromagnetic detection of complex surfaces such as crankshaft fillets and journals, two separate micromagnetic sensors are currently used for step-by-step detection, which reduces the detection efficiency. Since the two separate micromagnetic sensors have different magnetization parameters for the crankshaft, it is difficult to fuse and compare the data obtained by the two independent sensors in step-by-step detection, and it is not possible to perform synchronous micromagnetic evaluation of the mechanical properties of the crankshaft fillet and journal surface. To solve the above problems, the present invention discloses a micromagnetic sensor for the synchronous detection of crankshaft journals and transition fillets. It uses a single U-shaped electromagnet and two sets of detection elements arranged at an angle to achieve synchronous detection of multiple types of micromagnetic signals on the crankshaft fillet and journal surface. Summary of the Invention

[0003] The present invention aims to design a micromagnetic sensor for simultaneous detection of crankshaft journals and transition fillets. The ends of a U-shaped electromagnet's core are designed so that their inscribed planes contact the journal surface, forming a magnetic circuit. This allows for simultaneous magnetization of both the journal and transition fillet regions. Two sets of detection elements are positioned within the U-shaped electromagnet, their central axes forming a fixed angle, to detect four types of micromagnetic signals.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A micromagnetic sensor for simultaneous detection of crankshaft journals and transition fillets features an inscribed surface machined from the end face of a conventional U-shaped electromagnet core, which forms a magnetic circuit in contact with the journal surface. Under time-sharing excitation, two sets of detection elements detect four types of micromagnetic signals in the journal and transition fillet regions. The technical solution's implementation steps are as follows:

[0006] 1) Due to the geometric constraints of the crankshaft detection location, the end face of the electromagnet core is machined into an inscribed plane, improving the sensor's versatility. The electromagnet is constructed by spot-welding several sheets of 0.5mm thick non-oriented silicon steel. When the U-shaped electromagnet's excitation coil is subjected to multiple cycles of a low-frequency alternating signal, the generated alternating magnetic field simultaneously magnetizes the journal area and the transition fillet.

[0007] 2) During the low-frequency magnetization process only, the Hall element in the detection element measures the surface tangential magnetic field signal, the induction coil in the detection coil picks up the Barkhausen noise signal, and the output voltage signal is processed by filtering and amplifying and other conditioning methods; while the low-frequency magnetization is in progress, the excitation coil in the detection coil is applied with a high-frequency alternating signal, at which time the induction coil detects the incremental magnetic permeability signal; when only the excitation coil in the detection coil is fed with an alternating signal of multiple main frequencies, the signal output by the detection coil is a multi-frequency eddy current signal.

[0008] The present invention can achieve the following beneficial effects: the micromagnetic detection sensor realizes contact with the journal surface by processing the end face of the electromagnet core into an inner tangent surface, and simultaneously realizes magnetization of the journal and the transition fillet area, and realizes micromagnetic detection of the crankshaft journal and the transition fillet area through two sets of detection elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 : Overall schematic diagram of the sensor detecting at the crankshaft;

[0010] Figure 2 : Schematic diagram of the overall parts of the crankshaft micromagnetic sensor device;

[0011] Figure 3 : Schematic diagram of parts of crankshaft micromagnetic sensor detection device.

[0012] The figure numbers are as follows: 1-sensor upper side housing 2-sensor lower side housing 3-countersunk screw 4-countersunk screw 5-excitation coil fastening fixture 6-excitation coil fastening fixture 7-circuit board 8-circuit board 9-excitation coil 10-baffle 11-U-shaped magnetic yoke 12-spring 13-spring 14-spring 15-spring 16-Hall element 17-detection coil at the rounded corner 18-detection element fixing device at the rounded corner 19-detection element fixing device at the journal 20-Hall element 21-detection coil at the journal 22-crankshaft specimen 22_1-crankshaft crank 22_2-crankshaft journal 22_3-crankshaft transition fillet. DETAILED DESCRIPTION

[0013] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1The figure shows the overall schematic diagram of the sensor detecting at the crankshaft; Figure 2 The schematic diagram of the overall parts of the crankshaft micromagnetic sensor device is shown in FIG. Figure 3 The schematic diagram of the parts of the crankshaft micromagnetic sensor detection device is shown; based on the above invention content, a micromagnetic sensor for synchronous detection of crankshaft journal and transition fillet can provide the following implementation method.

[0015] After the sensor is placed close to the transition fillet, the electromagnet magnetizes the journal and the transition fillet simultaneously. The two sets of detection elements can realize the synchronous detection of four micro-magnetic signals, improve the efficiency of the circumferential scanning of the crankshaft, and at the same time, the data detected in the journal and transition fillet areas can be fused and compared.

[0016] The present invention will be further described below with reference to the accompanying drawings and the following embodiments. The specific implementation examples provided below are only illustrative and not restrictive, and cannot be used to limit the scope of protection of the present invention.

[0017] Figure 1 This is an overall schematic diagram of the micromagnetic detection sensor detecting at the crankshaft. The host computer can adjust the amplitude and frequency of the excitation coil and adjust the signal function generator through the control module. A low-frequency alternating current signal is passed through the excitation coil wound on the electromagnet core. An alternating magnetic field is generated internally, forming a circular magnetic circuit along the electromagnet and the crankshaft. The magnetic signals at the crankshaft journal and transition fillet are received through the detection coil and Hall element. The detection coil receives the magnetic Barkhausen noise signal, incremental magnetic permeability signal and eddy current signal through the instrument's time-sharing excitation method. The Hall element receives the surface tangential magnetic field signal, and the signal is displayed in real time on the host computer through the signal conditioning and receiving module.

[0018] Figure 2 A schematic diagram of the components of the micromagnetic sensor used for crankshaft detection. The sensor is used for simultaneous detection of the crankshaft journal and transition fillet. The end face of the electromagnet core is machined with an inscribed angle, and two sets of detection elements are used to detect multiple micromagnetic signals.

[0019] Figure 3Schematic diagram of the micromagnetic sensor detection element and fixture for detecting crankshaft journals and transition fillet areas. When the detection area is the crankshaft journal, the end face of the detection element fixture 19 is set to a plane, which can be used for crankshaft detection within a certain size range of the journal. The magnetic sensitive element is embedded inside and is in close contact with the detection surface through spring devices (14 and 15), ensuring that the sensor is well fitted with the surface of the test piece during each scanning experiment; when the detection area is the transition fillet of the crankshaft, the detection element fixture 18 is perpendicular to the cross-section of the transition fillet detection position point, and the curved surface of the fixture end face fits the fillet. At the same time, the other end of the detection element is assembled with the slot on the baffle 10 through springs (12 and 13), ensuring that the detection element and the crankshaft transition fillet maintain a constant posture to detect magnetic signals during the sensor detection process, thereby realizing the detection of the crankshaft transition fillet.

Claims

1. A micromagnetic sensor for synchronous detection of crankshaft journal and transition fillet, characterized in that: The end of the magnetic core of the U-shaped electromagnet is processed into an inscribed plane, which contacts the surface of the shaft neck to form a magnetic circuit. Inside the U-shaped electromagnet, two groups of detection elements are arranged in a plane perpendicular to the magnetic field direction. The central axes of the two groups of detection elements form a certain angle. The detection elements whose central axes are parallel to the shaft neck radial direction pick up the micromagnetic signals on the shaft neck surface, and the detection elements whose central axes intersect the shaft neck radially pick up the micromagnetic signals on the surface of the transition fillet area.

2. The micromagnetic sensor for synchronous detection of crankshaft journals and transition fillets according to claim 1, characterized in that: The detection elements are composed of Hall elements and detection coils.

3. The micromagnetic sensor for synchronous detection of crankshaft journals and transition fillets according to claim 2, characterized in that: The detection steps of the micromagnetic sensor are as follows: a. When the U-shaped electromagnet as a whole approaches the transition fillet area, a multi-cycle low-frequency sinusoidal current is passed through the excitation coil of the U-shaped electromagnet to provide an alternating magnetic field. The main magnetic circuit formed by the U-shaped electromagnet and the crankshaft is distributed along the circumference of the journal to magnetize the journal surface material. Part of the alternating magnetic field passes from the side of the U-shaped electromagnet through the transition fillet area and returns to the main magnetic circuit, magnetizing the material in the transition fillet area through the alternating magnetic field. b. During multi-cycle low-frequency magnetization, the Hall elements in both sets of detection elements measure the surface tangential magnetic field signal. The output voltage signal of the induction coil in the detection coil is bandpass filtered to obtain a magnetic Barkhausen noise signal. During the low-frequency magnetization process, a high-frequency current is simultaneously passed through the excitation coil in the detection coil, and the voltage signal output by the induction coil carries incremental magnetic permeability information. After the low-frequency magnetization is completed, a current with multiple main frequencies is passed through the excitation coil in the detection coil, and the voltage signal output by the induction coil is a multi-frequency eddy current signal.

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