Turning spiral line suspension wire detection method

Abstract

The invention provides a turning spiral line suspension wire detection method, which is characterized in that the surface of a workpiece is preliminarily screened through a suspension wire, when the suspension wire axially displaces, a workpiece rotation angle and a specific point location corresponding to the displacement are recorded, a defect area is quickly locked, and global blind detection is avoided; then, a contact probe of the fine detection device is used for conducting axial scanning in the flaw section with constant contact force, and vibration signals and position information are synchronously collected; the vibration sensor at the contact probe captures the vibration difference caused by the defect, and the processor accurately determines the specific position of the defect and quantifies the severity through the filtering processing, peak acceleration or energy value calculation and frequency domain analysis of the vibration signal, and distinguishes the defect type according to the high-frequency and low-frequency characteristics. By adopting the technical scheme, the integrated detection from rapid screening to accurate analysis is realized, and the special detection requirements that the traditional suspension wire detection is short in function, high in detection efficiency, accurate in result, adaptive to the defects of turning spiral lines and the like are effectively made up.

Description

Technical Field

[0001] This invention relates to the field of spiral wire inspection equipment, and more specifically to a method for inspecting the suspension wire of machined spiral wires. Background Technology

[0002] The hanging wire method for detecting spiral lines is a common and rapid screening method used in machining sites. It is often used to inspect the surface of sealing components. For example, if the surface of a pump hub has micro-spiral lines due to reasons such as axial movement of the grinding machine spindle, improper dressing of the grinding wheel, or unstable lathe feed, the hanging wire method is needed for rapid detection.

[0003] Currently, the method for detecting helical lines using a suspension wire involves suspending a weighted wire over the surface of a rotating pump hub. If continuous microscopic helical lines exist on the surface, the wire will move axially along the helical direction. By measuring the displacement distance of the wire after a period of rotation and comparing it with a preset threshold, a qualitative judgment can be made as to whether the workpiece is qualified.

[0004] However, since the contact arc length between the suspension line and the workpiece is approximately two-thirds of the workpiece's cross-sectional perimeter, when the inspection fails, this method can only indicate the presence of a defect on the workpiece surface, but cannot pinpoint the exact location of the defect. This means that defective products cannot be repaired locally and must be scrapped entirely, resulting in significant waste of materials and costs. Furthermore, this method can only provide a binary conclusion of "qualified" or "unqualified," and cannot quantitatively assess the severity of the defect. In addition, this method cannot distinguish the type of defect based on the detection signal, thus limiting its guiding role when adjusting lathes and grinding machines. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned technologies by proposing a method for detecting the suspension wire of a machining spiral, aiming to solve the problem that the existing suspension wire detection methods cannot quickly determine the specific location, severity, and type of defects.

[0006] This invention provides a method for detecting the suspension wire of a machining spiral, characterized by comprising the following steps; S1: Initial screening of defects: The workpiece surface is inspected using the suspension line method. Based on the axial displacement change of the suspension line relative to the workpiece surface, the defect area is initially determined. S2: Use a sophisticated detection device to collect defect information in the defective area: The precision inspection device includes an annular body fitted onto the surface of the workpiece, a single contact probe that can contact the surface of the workpiece, and a vibration sensor for collecting vibration signals from the contact probe. The annular body is fitted onto the workpiece, and the single contact probe performs contact scanning in the defect area, simultaneously collecting vibration signals and recording position information. S3: Defect Analysis: Based on the vibration signals and location information collected in step S2, determine the precise location, degree, and type of micro-defects.

[0007] Preferably, S11: The workpiece is divided into multiple detection areas along its axial direction, and a suspension line is used to detect each detection area; S12: Suspend the suspension wire according to the preset contact arc length between the suspension wire and the workpiece surface and the set starting detection position; control the workpiece to rotate according to the preset number of rotations, detect each detection area, and measure the axial displacement distance and displacement direction of the suspension wire within the predetermined rotation time; during the measurement process, prioritize the detection of preset high-defect areas. If the axial displacement of the suspension line exceeds the preset displacement threshold, mark the two sides of the suspension line where the displacement occurs, and preliminarily divide and determine the defect area based on the marks, and trigger the execution step S2.

[0008] Preferably, in step S2, contact scanning is performed on the defective segment determined in S1, specifically as follows: S21: The precision inspection device is fitted onto the workpiece, and the contact probe 2 is located within the defect area; S22: Apply force to the contact probe to control the contact force between the contact probe and the workpiece to be constant; rotate the workpiece so that the probe part of the contact probe contacts the workpiece surface; Preferably, determining the precise location of the microscopic defect in step S3 specifically includes: S31: The vibration signal is filtered by the processing unit of the precision detection device, the amplitude of the vibration pulse in the filtered signal is identified and compared with the preset vibration pulse threshold; if the amplitude of the vibration pulse exceeds the preset vibration pulse threshold, the position corresponding to the vibration pulse is the precise position of the micro defect.

[0009] Preferably, the quantification step of defect degree in step S3 is as follows: S32: Calculate the peak acceleration or vibration energy value of the vibration pulse, and quantitatively evaluate the severity of the micro-defect based on the preset evaluation criteria.

[0010] The defect type classification steps in step S3: S33: Perform frequency domain analysis on vibration signals and classify the types of micro-defects.

[0011] The classification of microscopic defects in step S33 is as follows: S331: If the high-frequency component dominates the vibration signal, the micro-defect is determined to be a point defect; S332: If the low-frequency component dominates the vibration signal, the micro-defect is determined to be a long strip-shaped continuous defect.

[0012] Preferably, the precision detection device further includes: Force control mechanism; A ring-shaped body is fitted onto the surface of the workpiece; The force control mechanism is a counterweight block located below the annular main body, and the counterweight block is hollow. The cavity contains a processor and a power supply. The processor is electrically connected to the vibration sensor, and the power supply provides power to the processor and the vibration sensor. The inner wall of the ring-shaped body is coated with a friction coating.

[0013] Preferably, the contact probe is embedded with a ball bearing, which is in contact with the surface of the workpiece.

[0014] Compared with existing technologies, it has the following beneficial effects: This invention provides a method for inspecting the suspension wire on a machined spiral. The method quickly determines whether a workpiece has defects and identifies the approximate area of ​​the defect. A contact probe of a precision inspection device accurately detects the defective section, pinpointing its exact location. A vibration sensor is installed at the contact probe, and the vibration of the probe is used to determine the type and severity of the defect. The above technical solution offers the following advantages: 1. The suspension wire inspection method can quickly detect whether there are defects on the surface of the workpiece, and the area where the defects are located; 2. By using a contact probe to detect defective sections, the location of defects can be quickly determined; 3. The degree of defect is quantified by the peak acceleration or vibration energy value of the vibration pulse, replacing the qualitative judgment of the traditional suspension wire inspection, so that the severity of the defect can be quantified; 4. By analyzing the frequency domain of the vibration signal, and based on the dominant characteristics of the high-frequency and low-frequency components, point defects and continuous defects can be accurately distinguished. 5. The force control mechanism, mainly composed of counterweights, provides constant contact force. Combined with the friction coating on the inner wall of the annular body, it reduces scanning resistance, ensuring stable contact between the contact probe and the workpiece surface while reducing the probability of workpiece damage. At the same time, the counterweights also serve as a storage compartment for the processor, improving space utilization and the stability of the annular body. 6. By detecting the severity and shape of defects, we can better guide subsequent feed adjustments and grinding wheel adjustments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of a method for detecting the suspension wire of a machining spiral according to the present invention; Figure 2 This is a schematic diagram of step S1 of the present invention; Figure 3 This is a schematic diagram of step S2 of the present invention; Figure 4 This is a schematic diagram of step S3 of the present invention; Figure 5 This is a schematic diagram of the precision detection device of the present invention; Figure 6 This is a partially enlarged schematic diagram of part A of the present invention; Figure 7 This is a schematic diagram of the vibration sensor and processor of the present invention.

[0016] In the figure, the ring-shaped body is 1; the contact probe is 2; the ball is 21; the vibration sensor is 3; the force control mechanism is 4; the counterweight is 41; the cavity is 411; the processor is 5; the power supply is 6; and the friction coating is 7. Detailed Implementation

[0017] To better understand the structure, functional features, and advantages of the present invention, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings: Example: like Figures 1 to 7 As shown, this invention provides a method for detecting spiral lines on a machining process using a suspended wire. The suspended wire detection utilizes a flexible wire (suspended wire) tensioned by a suspended weight to contact the surface of a rotating workpiece. When defects such as protrusions, depressions, or spiral lines exist on the workpiece surface, the suspended wire will experience axial displacement. By detecting this displacement, the presence of defects on the workpiece surface can be determined. The suspended wire adheres to the workpiece with a relatively large contact arc length (e.g., two-thirds of a circle). As the workpiece rotates, once it comes into contact with a defect, the suspended wire will immediately displace. However, suspended wire detection can only roughly determine the area where the defect exists (the defect area, i.e., within the two-thirds circle where the suspended wire contacts the workpiece), but it cannot precisely determine the exact point within this two-thirds circle; it can only determine whether the defect is present or not.

[0018] Therefore, the method proposed in this application includes S1: Initial screening of defects: The workpiece surface is inspected using the suspension line method. Based on the axial displacement change of the suspension line relative to the workpiece surface, the defect area is initially determined. S2: Use a sophisticated detection device to collect defect information in the defective area: The precision inspection device includes an annular body 1 fitted onto the surface of the workpiece, a single contact probe 2 that can contact the surface of the workpiece, and a vibration sensor 3 for collecting vibration signals from the contact probe 2. The annular body 1 is fitted onto the workpiece, and the single contact probe 2 performs contact scanning in the defect area, simultaneously collecting vibration signals and recording position information. S3: Defect Analysis: Based on the vibration signals and location information collected in step S2, determine the precise location, degree, and type of micro-defects.

[0019] The sophisticated testing equipment also includes: An annular body 1 is fitted onto the surface of the workpiece. The annular body 1 is a ring formed by a belt or rope, and is fitted onto the surface of the workpiece after step S1. The annular body 1 is made of a flexible material such as polyurethane.

[0020] A contact probe 2 is positioned at the top of the annular body 1 where it contacts the workpiece surface, and a vibration sensor 3 is positioned between the contact probe 2 and the annular body 1. A ball bearing 21 is embedded in the contact probe 2, and the ball bearing 21 is in contact with the workpiece surface. The contact probe 2 is screwed onto the inner wall of the annular body 1, specifically the side closest to the workpiece surface. A hole is formed in the inner wall of the annular body 1, and a threaded cylinder is glued to the hole wall; the contact probe 2 is screwed into this threaded cylinder. The ball bearing 21 is similar to the tip of a ballpoint pen or gel pen. The ball bearing 21 reduces the probability of scratching the workpiece surface.

[0021] The force control mechanism 4 is a counterweight 41 set below the annular main body 1, and the counterweight 41 is set with a cavity 411; A processor 5 and a power supply 6 are installed inside the cavity 411. The processor 5 is electrically connected to the vibration sensor 3, and the power supply 6 supplies power to the processor 5 and the vibration sensor 3. The power supply lines and transmission lines are both integrated within the annular body 1.

[0022] The counterweight 41 can be a high-density metal block such as cast iron. The two ends of the annular body 1 are connected to the end caps used to fill the cavity 411. This connection can be achieved by gluing or by pressing the two ends of the annular body 11 against the edge of the end cap through an interference fit. This application uses an end cap pressing method, which reduces the probability of the annular body getting tangled and facilitates the disassembly and replacement of the power supply 6.

[0023] The inner wall of the annular body 1 is coated with a friction coating 7. The friction coating 7 is a polytetrafluoroethylene (PTFE) coating, used to reduce the friction between the inner wall of the annular body 1 and the surface of the workpiece. This reduces the probability that the annular body 1 will rotate with the workpiece due to high friction.

[0024] As another embodiment, such as Figure 1 and Figure 2 As shown, this application S11: The workpiece is divided into multiple inspection areas along its axial direction, and a plumb line inspects each area. Dividing the workpiece into multiple inspection areas can narrow down the defect location range, avoid blind inspection of the entire area, and improve the targeted accuracy of subsequent inspections; at the same time, it ensures that no inspection is missed and adapts to the inspection needs of different areas. The area division is based on the workpiece structure and defect distribution patterns (such as subdivision near key features), and uniform division is used when there are no special patterns; the area size is adjusted according to the positioning accuracy requirements, and the start and end positions of the area are preset by the inspection system.

[0025] S12: Suspend the suspension wire according to the preset contact arc length between the suspension wire and the workpiece surface and the set starting detection position; control the workpiece to rotate according to the preset number of rotations, detect each detection area, and measure the axial displacement distance and displacement direction of the suspension wire within the predetermined rotation time; during the measurement process, prioritize the detection of preset high-defect areas. If the axial displacement of the suspension line exceeds the preset displacement threshold, mark the two sides of the suspension line where the displacement occurs, and preliminarily divide and determine the defect area based on the marks, and trigger the execution step S2.

[0026] Areas with a high incidence of defects (such as parts that are difficult to process or have complex structures) have a higher probability of developing flaws. Prioritizing these areas for inspection can quickly identify problems and reduce wasted inspection time. The contact arc length between the suspension wire and the workpiece surface is typically about two-thirds of the workpiece surface area.

[0027] Multiple rotations in each detection area eliminate false displacements caused by impurities and vibrations, improving detection reliability. Displacement distance and direction can be determined based on the displacement of the counterweight below the suspension line, or by observing the different positions of the counterweight on the scale. Suspension line detection can experience false movements due to friction, so a preset displacement threshold is necessary; displacements exceeding this threshold are considered defects. This threshold is set differently for different workpieces.

[0028] Defective areas need to be marked on the workpiece surface with a marker. After the final inspection, the marked locations can be counted and then erased. Once a workpiece is determined to be defective, step S2 is required for further confirmation.

[0029] As another embodiment, such as Figure 1 and Figure 3 As shown, in step S2 of this application, a contact scan is performed on the defective area determined in S1, specifically as follows: S21: A precision inspection device is fitted onto the workpiece, with the contact probe 2 located within the defect area. Direct inspection within the defect area effectively reduces the time spent searching for defects.

[0030] S22: Apply force to the contact probe 2 to control the contact force between the contact probe 2 and the workpiece to be constant; rotate the workpiece so that the probe part of the contact probe 2 contacts the surface of the workpiece.

[0031] The force control mechanism 4, also known as the counterweight 41, can adjust the tension of the annular body 1 by adjusting the weight of the counterweight 41. This ensures that the contact probe 2 is in close contact with the workpiece surface and is not limited by the annular body 1 on both sides of the contact probe 2, and is not pressed too tightly to avoid excessive friction.

[0032] The contact probe requires point-by-point scanning and analysis of vibration signals, which is time-consuming for full-area detection and unsuitable for the rapid screening needs of mass production. Furthermore, its complex structure and high cost mean that full-area application would increase detection costs, equipment wear and tear, and time consumption. Therefore, it is necessary to first use a suspension wire for detection, followed by contact probe 2. The probe part of contact probe 2 is the ball bearing 21.

[0033] As another embodiment, such as Figure 1 and Figure 4 As shown, step S3 of this application, determining the precise location of the microscopic defect, specifically includes: S31: The processing unit of the precision detection device filters the vibration signal, identifies the amplitude of the vibration pulse in the filtered signal, and compares it with a preset vibration pulse threshold. If the amplitude of the vibration pulse exceeds the preset threshold, the location corresponding to the vibration pulse is the precise location of the microscopic defect. The vibration pulse threshold is determined through extensive experiments using standard specimens known to contain different types and sizes of defects for scanning and acquiring their vibration signals. The amplitude range of vibration pulses caused by defects is analyzed, and a second threshold is set at a level slightly higher than the signal amplitude caused by normal background noise and surface roughness, but still reliably capturing the minimum acceptable defect signal amplitude. This value needs to strike a balance between avoiding missed detections and reducing false detections. It serves as a benchmark for determining whether a signal is caused by a real defect. It is used to identify abnormal vibration signals caused by defects (such as protrusions, depressions, and cracks) from background noise and normal surface roughness signals. When the instantaneous amplitude (or peak value, RMS value) of the signal exceeds the preset vibration pulse threshold, the system considers that a potential defect event has been detected at that moment (or at that location) and marks it as a "vibration pulse".

[0034] Step S3 involves quantifying the degree of defect: S32: Calculate the peak acceleration or vibration energy value of the vibration pulse, and quantitatively evaluate the severity of the micro-defect based on preset evaluation criteria. The peak acceleration of the pulse is the maximum acceleration value in the vibration pulse waveform. The processing unit directly extracts the maximum instantaneous value of each identified vibration pulse from the filtered vibration acceleration signal. Generally, the larger and deeper the defect, or the more intense the interaction with the probe, the higher the peak acceleration. It is a relatively intuitive intensity indicator. The vibration energy value is the energy contained in the vibration pulse within a certain time window. The higher the energy value, the more severe the defect. In preliminary experiments, the severity of the defect was classified according to the peak acceleration or vibration energy value of the vibration pulse. In the detection process, the peak acceleration or vibration energy value of the vibration pulse corresponds to the defect level.

[0035] The defect type classification step described in step S3: S33: Perform frequency domain analysis on vibration signals and classify the types of micro-defects.

[0036] The classification of microscopic defects in step S33 is as follows: S331: If the high-frequency component dominates the vibration signal, the micro-defect is determined to be a point defect; S332: If the low-frequency component dominates the vibration signal, the micro-defect is determined to be a long strip-shaped continuous defect.

[0037] When different types of defects (such as dot-like bumps, fine scratches, and spiral deviations) interact with a contact probe, they excite vibrations of different frequencies due to their varying geometry and size. Time-domain signals (time-amplitude) cannot directly distinguish these differences, while frequency-domain analysis (frequency-amplitude / power) can decompose the signal into sinusoidal components of different frequencies, thus revealing its inherent frequency characteristics.

[0038] Extensive experimental testing is conducted beforehand on various known types of typical defects (such as pitting, scratches, cracks, protrusions, and spiral lead errors). Frequency domain analysis is performed on the vibration signal of each sample to extract its unique frequency characteristics (such as peak frequency and dominant frequency band), and these characteristics are correlated with the corresponding defect type to establish a "defect type-frequency characteristic" database or classification model. Step S3 extracts the precise location, quantified severity, and specific type of micro-defects from the original vibration signal, providing valuable data support for subsequent quality assessment and process improvement.

[0039] After processing the data such as defect location, severity, and type, processor 5 transmits it to a mobile phone or computer terminal connected to processor 5 via network or Bluetooth for visualization. Compared with existing detection facilities such as laser inspection, this application is more flexible, enabling defect judgment and timely adjustment of production equipment parameters at the first moment of production.

[0040] The working principle of the spiral wire detection method for machining described in this application is as follows: First, a rapid initial screening is performed using the suspension wire detection method: A flexible wire with a suspended counterweight is attached to the surface of the rotating workpiece at approximately two-thirds of its circumference. When defects such as protrusions, depressions, or spirals exist within this area, the suspension wire will generate an overall axial displacement. By monitoring whether the displacement exceeds a threshold, the "suspicious defect area" can be quickly identified. Subsequently, contact vibration detection is initiated for precise quantitative analysis: A flexible detection ring equipped with a ball bearing probe is placed over the suspicious area. Under the control of the counterweight, the probe contacts the surface with constant pressure. When the workpiece rotates, the ball bearing scans the defect, which excites characteristic vibrations. The vibration signal is processed in real time. The precise location is determined by amplitude comparison, the degree of defect is quantified by peak energy calculation, and the defect type is identified by spectrum analysis (high frequency predominates for point defects, low frequency predominates for strip defects). Finally, all data is wirelessly transmitted to a terminal to generate a visual report.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of the present invention without departing from the scope of the present invention are within the protection scope of the present invention.

Claims

1. A method for detecting the suspension wire of a machined spiral, characterized in that, Includes the following steps; S1: Initial screening of defects: The workpiece surface is inspected using the suspension line method. Based on the axial displacement change of the suspension line relative to the workpiece surface, the defect area is initially determined. S2: A precision detection device is used to collect defect information in the defective area. The precision inspection device includes an annular body (1) fitted onto the surface of the workpiece, a single contact probe (2) that can contact the surface of the workpiece, and a vibration sensor (3) for collecting vibration signals from the contact probe (2). The annular body (1) is fitted onto the workpiece, and the single contact probe (2) performs contact scanning in the defect area, simultaneously collecting vibration signals and recording position information. S3: Defect Analysis: Based on the vibration signals and location information collected in step S2, determine the precise location, degree, and type of micro-defects.

2. The method for detecting the suspension wire of a machining spiral as described in claim 1, characterized in that, S11: The workpiece is divided into multiple detection areas along its axial direction, and the suspension line detects each detection area; S12: Suspend the workpiece according to the preset contact arc length between the suspension line and the workpiece surface and the set starting detection position; control the workpiece to rotate according to the preset number of rotations, detect each detection area, and measure the axial displacement distance and displacement direction of the suspension line within a predetermined rotation time; during the measurement process, prioritize the detection of preset high-defect areas. If the axial displacement distance of the suspension line exceeds the preset displacement threshold, the two sides of the suspension line where the displacement occurs are marked, and the defect area is initially determined based on the marks, and step S2 is triggered.

3. The method for detecting the suspension wire of a machining spiral as described in claim 1, characterized in that, Step S2, which involves performing a contact scan on the defective area determined in S1, specifically includes: S21: The precision inspection device is fitted onto the workpiece, and the contact probe (2) is located within the defect area; S22: Apply force to the contact probe (2) to control the contact force between the contact probe (2) and the workpiece to be constant; rotate the workpiece so that the probe part of the contact probe (2) contacts the surface of the workpiece.

4. The method for detecting the suspension wire of a machining spiral as described in claim 1, characterized in that, Step S3, which involves determining the precise location of the microscopic defects, specifically includes: S31: The processing unit of the precision detection device filters the vibration signal, identifies the amplitude of the vibration pulse in the filtered signal, and compares it with a preset vibration pulse threshold; if the amplitude of the vibration pulse exceeds the preset vibration pulse threshold, the position corresponding to the vibration pulse is the precise position of the micro defect.

5. The method for detecting the suspension wire of a machining spiral as described in claim 4, characterized in that, The quantification step of the defect degree described in step S3: S32: Calculate the peak acceleration or vibration energy value of the vibration pulse, and quantitatively evaluate the severity of the micro-defect based on the preset evaluation criteria.

6. The method for detecting the suspension wire of a machining spiral as described in claim 5, characterized in that, The defect type classification step described in step S3: S33: Perform frequency domain analysis on the vibration signal and classify the types of micro-defects.

7. The method for detecting the suspension wire of a machining spiral as described in claim 6, characterized in that, The classification of microscopic defect types in step S33 specifically involves: S331: If the high-frequency component dominates the vibration signal, then the micro-defect is determined to be a point defect; S332: If the low-frequency component dominates the vibration signal, then the micro-defect is determined to be a long strip-shaped continuous defect.

8. The method for detecting the suspension wire of a machining spiral as described in claim 7, characterized in that, The precision detection device also includes: a force control mechanism (4); An annular body (1) is sleeved on the surface of the workpiece; The force control mechanism (4) is a counterweight (41) provided below the annular body (1), and the counterweight (41) is provided with a cavity (411); The cavity (411) is provided with a processor (5) and a power supply (6). The processor (5) is electrically connected to the vibration sensor (3), and the power supply (6) supplies power to the processor (5) and the vibration sensor (3). The inner wall of the annular body (1) is coated with a friction coating (7).

9. The precision detection device according to claim 8, characterized in that, The contact probe (2) is embedded with a ball (21), which is in contact with the surface of the workpiece.

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