Non-destructive method for detecting the angle of a steel cord of a tire belt

Abstract

This invention discloses a non-destructive method for detecting the angle of steel wires in a tire belt layer. The method includes: placing physical markers on the tread surface of the tire under test; performing an X-ray scan on the tire with the physical markers to obtain an X-ray image; dynamically adjusting the position of the physical markers on the tread surface based on the X-ray image until the projected image of the physical markers on the X-ray image is spatially aligned with the projected image of a target steel wire in the internal belt layer; determining the spatial orientation of the adjusted and aligned physical markers on the tread surface; and calculating the angle of the target steel wire based on this spatial orientation. This invention achieves direct imprinting and high-precision measurement of angles by adjusting the placement of the tread steel wires in real time to match the spatial trajectory of the belt layer steel wires.

Description

Technical Field

[0001] This invention relates to the field of tire testing technology, and in particular to a non-destructive testing method for the angle of the steel wires in the tire belt layer. Background Technology

[0002] As the core load-bearing skeleton of a tire, the belt layer bears more than 70% of the air pressure load on the tire crown. The laying angle of its steel cords directly affects key performance characteristics such as tire inflation pattern, rolling resistance, and durability. Therefore, accurately obtaining the actual angle of the belt layer in the finished tire is crucial—it can be used to verify whether the belt layer angle after vulcanization meets the design requirements, and it also helps to improve the accuracy of simulation analysis.

[0003] Traditional methods for measuring belt layer angles primarily employ the tire dissection method, which involves peeling off the rubber material above the belt layer to expose the steel cords and then directly measuring with a protractor. This method has the following drawbacks: firstly, the operation is time-consuming and labor-intensive, resulting in low efficiency; secondly, after being peeled off, the steel cords, no longer bound by the rubber material, are prone to changes in position and shape, leading to deviations in the measurement results from the actual angle when the tire is intact, thus affecting the accuracy of the test.

[0004] To address the aforementioned issues, several non-destructive testing methods have been developed in the existing technology.

[0005] Patent document CN114441563A discloses a "method for quality inspection of belt layers in engineering radial tires." This method employs a non-destructive approach combining "manufacturing marking + X-ray inspection + CAD measurement." The specific process is as follows: during belt layer bonding, the joints of each layer are marked; after tire blank pressing and vulcanization, the markings are transferred to the tire sidewall; the finished tire is marked with a metal reference and then subjected to X-ray inspection; the image is imported into CAD software, and the angle and width of the steel wires are measured and drawn accordingly. While this method achieves non-destructive testing, it has the following shortcomings: the operation process is cumbersome, relying on marking at multiple stages throughout the tire manufacturing process; the marking transfer process is easily affected by fluctuations in the production process; and its applicability is limited, mainly targeting semi-finished tires in the manufacturing process, and is difficult to apply to finished tires that have already undergone vulcanization.

[0006] Patent document CN118089610A discloses a "method, device, and computer program for measuring the angle of the belt layer of a radial tire." This method uses "reference calibration + X-ray scanning" to measure the angle. The steps are as follows: a slender reference object that cannot be penetrated by X-rays is attached to the tire tread, and its initial angle with the tire's circumference is recorded; after X-ray scanning, the image is imported into CAD software, the angle deviation of the reference object is calculated, and then the belt layer shadow is corrected based on the deviation to measure the angle, thus obtaining the actual angle. This method does not require intervention in the manufacturing process, but it still has the following technical drawbacks: First, the indirect calculation method of correcting the belt layer angle through the reference object angle deviation is prone to accumulated errors due to reference object attachment deviation and scanning imaging distortion; second, it requires a high level of operator skill, and the accuracy of the reference object attachment position and angle recording directly affects the measurement results.

[0007] In summary, there is currently a lack of a non-destructive testing method for the angle of the belt layer steel wires that can achieve high precision, high efficiency, applicability to finished tires, and ease of operation. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology. To achieve the above objective, a non-destructive testing method for the angle of the steel wires in the tire belt layer is adopted to solve the problems mentioned in the background technology.

[0009] A non-destructive testing method for the angle of steel wires in tire belt layers includes the following steps: Step S1: Set physical markers on the tread surface of the tire to be tested; Step S2: Perform an X-ray scan on the tire with the physical markers to obtain an X-ray image containing the internal belt layer steel wires and the physical markers; Step S3: Based on the X-ray image, dynamically adjust the position of the physical marker on the tread surface until the projection image of the physical marker on the X-ray image is spatially aligned with the projection image of a target wire in the internal belt layer steel wire. Step S4: Determine the spatial orientation of the physical marker on the tire tread surface after adjustment and spatial alignment in step S3, and calculate the angle of the target steel wire based on the spatial orientation.

[0010] As a further aspect of the present invention: step S3 further includes: The alignment deviation between the physical marker and the target wire is analyzed based on the current X-ray image. Adjust the position of the physical marker according to the alignment deviation; The adjusted tires are then subjected to another X-ray scan to verify the alignment effect until the alignment deviation is less than a preset threshold.

[0011] As a further aspect of the present invention: the physical marker is a thin metal wire with a diameter comparable to that of the steel wire in the belt layer.

[0012] As a further aspect of the present invention: the spatial alignment in step S3 means that the projection image of the physical marker on the X-ray image completely overlaps with the projection image of the target wire.

[0013] As a further aspect of the present invention: determining the spatial orientation of the physical marker in step S4 includes: The adjusted and fixed shape of the physical marker is transferred onto the recording medium by a physical imprinting method; The angle of the imprint on the recording medium is measured as the angle of the target steel wire.

[0014] As a further aspect of the present invention: the tire to be tested is a finished tire that has already undergone vulcanization.

[0015] As a further aspect of the present invention: before testing, the surface and interior of the tire to be tested do not contain any preset marks for angle measurement.

[0016] As a further aspect of the present invention, the preset threshold is ±0.3°.

[0017] As a further aspect of the present invention, it also includes fixing the adjusted physical markers to the tread surface using adhesive tape.

[0018] As a further aspect of the present invention, the physical imprinting method includes: applying pressure to the adjusted and fixed physical marker to imprint its shape onto the recording medium to form an indentation.

[0019] Compared with the prior art, the present invention has the following technical advantages: 1. High Precision: This invention employs a "physical alignment + direct imprinting" technical concept, physically replicating the angle of the internal belt layer steel wires onto the tread markings through spatial alignment. The angle value is then obtained by measuring the markings, representing a direct mapping measurement that effectively breaks the multi-step error chain in traditional indirect calculations. Actual measurements show that the method of this invention can achieve a measurement accuracy within ±0.3°, superior to existing technologies.

[0020] 2. Wide range of applications: This invention does not rely on any preset markings and can directly inspect finished tires that have completed vulcanization. It breaks through the limitation of existing technologies that are limited to semi-finished tires and can be widely used in various scenarios such as final inspection of production lines, random inspection of incoming goods, and random inspection of tires in the market.

[0021] 3. Simple operation and strong robustness: This invention simplifies the complex requirement of "one-time alignment" into high-precision alignment that can be achieved through simple iteration by using a closed-loop feedback process of "scan-analysis-adjustment-re-scan". This reduces the dependence on the operator's experience and improves the operability and repeatability of the method.

[0022] 4. Solid theoretical support: This invention proves through rigorous mathematical models that under point light source projection, the helix angle of the projection from one cylindrical surface to another coaxial cylindrical surface remains unchanged, providing a solid theoretical foundation for the "physical tracing" method and ensuring its scientific validity and accuracy. Attached Figure Description

[0023] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of an embodiment disclosed in this application; Figure 2 A schematic diagram illustrating the coordinate system establishment of the geometric model in an embodiment of this application; Figure 3 This is a structural block diagram of a tire belt layer steel wire angle detection device according to an embodiment of this application; Figure 4 An X-ray image of the steel wire after its position has been adjusted according to the embodiment disclosed in this application. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 Please refer to Figure 1 In this embodiment of the invention, a non-destructive testing method for the angle of steel wires in a tire belt layer includes the following steps: Step S1: Set physical markers on the tread surface of the tire to be tested; Select a thin, long metal wire as a physical marker. This wire is preferably steel wire, and its diameter should be approximately the same as the diameter of the steel wire in the belt layer of the tire being tested. Initially attach the wire to the tread surface of the tire being tested according to the designed angle of the belt layer (if no designed angle is specified, an X-ray scan can be used to observe the approximate angle first). This initial attachment is only for temporary fixation to ensure that adjustments can be made later.

[0026] like Figure 2 As shown, the diagram illustrates the establishment of the coordinate system for the geometric model; Step S2: Perform an X-ray scan on the tire with the physical markers to obtain an X-ray image containing the internal belt layer steel wires and the physical markers; Place the tire with the attached metal wires in the X-ray scanning equipment. Turn on the X-ray source and X-ray detector to perform a 360° or partial scan of the tire, obtaining X-ray images that include the internal belt layer steel wires and the tread metal wires.

[0027] Step S3: Based on the X-ray image, dynamically adjust the position of the physical marker on the tread surface until the projection image of the physical marker on the X-ray image is spatially aligned with the projection image of a target wire in the internal belt layer steel wire. In this embodiment, step S3 further includes: The alignment deviation between the physical marker and the target wire is analyzed based on the current X-ray image. Adjust the position of the physical marker according to the alignment deviation; The adjusted tires are then subjected to another X-ray scan to verify the alignment effect until the alignment deviation is less than a preset threshold.

[0028] In this embodiment, the physical marker is a thin metal wire with a diameter similar to that of the steel wire in the belt layer.

[0029] In this embodiment, spatial alignment in step S3 means that the projection image of the physical marker on the X-ray image completely overlaps with the projection image of the target wire.

[0030] The acquired X-ray images are displayed on a monitor. The operator observes the images, identifies a specific target steel wire in the belt layer, and observes the positional relationship between the projected image of the tread metal wire and the projected image of the target steel wire.

[0031] Based on the observed deviations, operators use non-metallic tools (such as plastic tweezers) to slightly adjust the position of the tire tread wires, gradually bringing their projection on the X-ray image closer to the projection of the target wire. Each adjustment is verified by a short X-ray scan, forming a closed-loop feedback process of "scan-analysis-adjustment-re-scan".

[0032] The above process is repeated until the deviation between the projected image of the tread metal wire and the projected image of the target steel wire on the X-ray image is less than a preset threshold. In this embodiment, the preset threshold is set to ±0.3°. When the deviation is less than this threshold, the two are considered to have achieved spatial alignment.

[0033] Step S4: Determine the spatial orientation of the physical marker on the tire tread surface after adjustment and spatial alignment in step S3, and calculate the angle of the target steel wire based on the spatial orientation.

[0034] In this embodiment, determining the spatial pose of the physical marker in step S4 includes: The adjusted and fixed shape of the physical marker is transferred onto the recording medium by a physical imprinting method; The angle of the imprint on the recording medium is measured as the angle of the target steel wire.

[0035] In this embodiment, the tire to be tested is a finished tire that has already undergone vulcanization.

[0036] In this embodiment, the tire under test does not contain any preset marks for angle measurement on its surface or inside before testing. The preset threshold is ±0.3°.

[0037] In this embodiment, the method further includes fixing the adjusted physical markers to the tread surface using adhesive tape.

[0038] In this embodiment, the physical imprinting method includes: applying pressure to the adjusted and fixed physical marker to imprint its shape onto the recording medium to form an indentation.

[0039] After confirming alignment, use tape to firmly fix the adjusted wire to the tire tread surface to prevent it from shifting during subsequent operations.

[0040] Use a sheet of white paper as the recording medium and place it over the tire tread area where the metal wire is fixed. Apply uniform pressure over the paper to transfer the shape of the metal wire onto the paper through an imprinting process, forming a clear imprint. This imprint is a physical record of the spatial orientation of the metal wire on the tire tread surface.

[0041] Angle calculation The angle between the rubbing on the recording medium and the circumferential direction of the tire is measured using a protractor; this angle is the actual angle of the target steel wire. To reduce measurement error, multiple measurements can be taken at different locations, and the average value taken.

[0042] Example 2 like Figure 3 The diagram shows a structural block diagram of a tire belt layer steel wire angle detection device. like Figure 4 As shown, the image is an X-ray image after the steel wire position has been adjusted. This embodiment is a specific implementation based on Embodiment 1, and the specific measuring tools and steps are as follows: Selection of measuring tools: X-ray equipment specifically designed for scanning car tires, steel wire, protractor, tape, etc.

[0043] Measurement steps: 1) Attaching steel wires to the tread: To accurately measure the angle of the actual tire belt layer, a thin steel wire with a diameter close to that of the actual belt layer steel wire is needed. Attach the wire to the tread according to the designed angle of the belt layer (if there is no designed angle for the belt layer, you can first scan the approximate position of the belt layer steel wire with an X-ray, and then attach the wire to the approximate position).

[0044] 2) X-ray scanning: The solid tire with the steel wire attached is placed under an X-ray and scanned. Based on the X-ray scan results, the position of the steel wire on the tire tread is adjusted in real time so that the position of the steel wire on the tire tread coincides with the position of a certain steel wire in the actual belt layer under the X-ray.

[0045] 3) Fixing the tread wires: Fix the adjusted tread wires with tape.

[0046] 4) Tread wire position tracing: Trace the fixed tread wires to obtain the tread wire angles and belt layer angles.

[0047] At this point, the angle of the fixed tread steel wire is basically equal to the angle of the actual belt layer.

[0048] The method of the present invention is based on the following geometric principle: under point light source projection conditions, the helix angle of the projection from one cylindrical surface to another coaxial cylindrical surface remains unchanged.

[0049] Assumption: The plane of the belt layer steel wires is parallel to the tread.

[0050] Proof: The angle of the parallel plane remains unchanged when it is projected through a point. In other words, when the belt layer steel wire is projected onto the tire surface during point projection, its projection angle is the same as the actual belt layer angle.

[0051] The proof is as follows: First, simplify the model: Let the X-ray source be a point source located at the origin O(0,0,0); the radius of the cylindrical surface (inner cylinder) where the belt layer is located is r, and the radius of the cylindrical surface (outer cylinder) where the tread is located is R, and R>r. The two cylinders are coaxial, and the axis is the Z-axis.

[0052] Question: When a point light source projects a steel wire onto an outer cylindrical surface (radius: R), what is the angle between the curve projected onto the outer cylindrical surface and the generatrix of the cylinder? (i.e., the spiral angle of the projection)? Establish a coordinate system: Let the axis of the cylinder be the Z-axis, and the point light source be located at the origin O (0,0,0).

[0053] Equation of the inner cylindrical surface:

[0054] Equation of the outer cylindrical surface:

[0055] Description of the steel wire on the inner cylinder: The inner cylinder can be used with parameters ( , , z) represents, where z is the axial coordinate.

[0056] The "generatrix" of a cylinder is a straight line parallel to the z-axis (θ is fixed on the cylinder surface).

[0057] The angle between the steel wire and the busbar is This means that on the unfolded diagram, the angle between the wire and the z-axis is... .

[0058] In the unfolded diagram, the cylindrical surface is cut along a generatrix and flattened into a rectangle, with the horizontal direction representing the arc length. The vertical direction is z.

[0059] The steel wire is a straight line on the unfolded diagram, and its slope is:

[0060] Right now:

[0061] so:

[0062] Integral result:

[0063] Under normal circumstances, take The parametric equation for the steel wire is (on the inner cylindrical surface):

[0064] When projected onto the outer cylindrical surface, the point light source is at the origin, and the projection line goes from O through a point P on the wire to the outer cylindrical surface.

[0065] Let Q be the projection point on the outer cylinder, then (Because it starts from the origin), and Q satisfies .

[0066] for ,have:

[0067] Requirements for the outer cylinder radius R:

[0068] so:

[0069] Parametric form of the outer cylinder (using the same θ coordinates):

[0070] here:

[0071] On the unfolded diagram of the outer cylinder, the horizontal coordinate is... The vertical coordinate is z.

[0072] so:

[0073] On the unfolded graph, this is a straight line with the following slope:

[0074] This shows that the angle between the projected curve and the generatrix of the outer cylinder is still... .

[0075] Conclusion: When projecting a point onto a plane, the angle of the steel wire projection onto any parallel plane remains unchanged. That is, the angle of the fixed tread steel wire is essentially equal to the actual belt layer angle.

[0076] The beneficial effects of this invention are: It overcomes the problems of existing technologies, such as reliance on preset markings, applicability only to semi-finished tires, complex operation, and limited accuracy. By adjusting the position of the tread steel wires in real time to match the spatial trajectory of the belt layer steel wires, it achieves direct tracing and high-precision measurement of angles. It has significant advantages such as no marking required, applicability to finished tires, simple process, small error, and low cost. It is especially suitable for quality control and after-sales inspection scenarios throughout the tire manufacturing process.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents, all of which should be included within the scope of protection of the invention.

Claims

1. A non-destructive testing method for the angle of steel wires in a tire belt layer, characterized in that, Includes the following steps: Step S1: Set physical markers on the tread surface of the tire to be tested; Step S2: Perform an X-ray scan on the tire with the physical markers to obtain an X-ray image containing the internal belt layer steel wires and the physical markers; Step S3: Based on the X-ray image, dynamically adjust the position of the physical marker on the tread surface until the projection image of the physical marker on the X-ray image is spatially aligned with the projection image of a target wire in the internal belt layer steel wire. Step S4: Determine the spatial orientation of the physical marker on the tire tread surface after adjustment and spatial alignment in step S3, and calculate the angle of the target steel wire based on the spatial orientation.

2. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1, characterized in that, Step S3 further includes: The alignment deviation between the physical marker and the target wire is analyzed based on the current X-ray image. Adjust the position of the physical marker according to the alignment deviation; The adjusted tires are then subjected to another X-ray scan to verify the alignment effect until the alignment deviation is less than a preset threshold.

3. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1 or 2, characterized in that, The physical marker is a thin, long metal wire with a diameter similar to that of the steel wire in the belt layer.

4. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1, characterized in that, The spatial alignment in step S3 means that the projection image of the physical marker on the X-ray image completely overlaps with the projection image of the target wire.

5. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1, characterized in that, Determining the spatial orientation of the physical marker in step S4 includes: The adjusted and fixed shape of the physical marker is transferred onto the recording medium by a physical imprinting method; The angle of the imprint on the recording medium is measured as the angle of the target steel wire.

6. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1, characterized in that, The tire to be tested is a finished tire that has already undergone vulcanization.

7. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 1, characterized in that, Before testing, the tire under test does not contain any preset markings on its surface or inside for angle measurement.

8. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 2, characterized in that, The preset threshold is ±0.3°.

9. The non-destructive testing method for the angle of steel wires in the tire belt layer according to claim 1, characterized in that, Also includes: The adjusted physical markers are fixed to the tread surface using tape.

10. The non-destructive testing method for the angle of the steel wires in the tire belt layer according to claim 5, characterized in that, The physical imprinting method includes: applying pressure to the adjusted and fixed physical marker to imprint its shape onto the recording medium to form an indentation.

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