A non-contact wave shape evolution process testing method and device for precision ultra-thin strips

Abstract

The present invention discloses a non-contact wave shape evolution process testing method and device for precision ultra-thin strips, wherein the testing method comprises: obtaining an ultra-thin strip sample with wave shape defects, forming original speckles on the surface of the ultra-thin strip sample based on black and white spray paint; evaluating the original speckles, and if the quality of the original speckles meets the requirements, calibrating the original speckles based on a calibration plate; continuously applying tension to the ultra-thin strip sample, and when the surface of the ultra-thin strip sample changes from undulating to straight, maintaining the tension to keep the ultra-thin strip sample in a straight state, and recording the tension value in the straight state; stopping maintaining the tension, and obtaining the shape, displacement and strain data of the ultra-thin strip sample based on a high-speed camera. The present invention facilitates the study of elastic buckling theory by obtaining the wave shape evolution process and geometric characteristic parameters of the strip sample.

Description

Technical Field

[0001] The present invention belongs to the field of non-contact detection of wave shape of precision ultra-thin strips, and in particular relates to a method and device for testing the non-contact wave shape evolution process of precision ultra-thin strips. Background Art

[0002] The development of micro-manufacturing and microelectronics industries towards intelligence, mobility, high density and high reliability has led to a surge in demand for ultra-thin metal strips with thinner thickness and higher dimensional accuracy. In order to improve efficiency, the ultra-thin and wide-width production of precision ultra-thin strips has become a trend. While the thickness of the strip is reduced, the complex wave shape problem caused by the large residual stress generated by the uneven plastic deformation of the strip metal has become prominent. In other words, it is particularly important to clarify the corresponding relationship between the residual stress distribution and the complex wave shape.

[0003] During the cold rolling process of precision ultra-thin strips, due to the low bending stiffness, the strip becomes unstable and releases residual stress to produce complex wave shapes. The diversity and complexity of the wave shape manifestations make it difficult to study the plastic deformation of ultra-thin metal strips and the wave shape generation mechanism. Therefore, it is required to accurately measure the residual stress distribution of ultra-thin strips with plate shape problems and their wave shape after release. It is necessary to find different residual stress distributions and their corresponding wave shapes and then use the elastic buckling theory to study them. However, the strip thickness is small, the residual stress value is small, and the longitudinal fluctuation value is small. At present, there is no means to measure the corresponding relationship between the two. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for testing the wave shape evolution process of a precision ultra-thin strip in a non-contact manner, so as to solve the problems existing in the above-mentioned prior art.

[0005] On the one hand, to achieve the above-mentioned purpose, the present invention provides a non-contact wave shape evolution process testing method for a precision ultra-thin strip, comprising:

[0006] An ultra-thin strip sample with a wave-shaped defect is obtained, and original speckles are formed on the surface of the ultra-thin strip sample based on black and white spray paint;

[0007] evaluating the original speckle pattern, and if the quality of the original speckle pattern meets the requirement, calibrating the original speckle pattern based on a calibration plate;

[0008] Continuously applying tension to the ultra-thin strip sample, and when the surface of the ultra-thin strip sample changes from undulating to straight, maintaining the tension to keep the ultra-thin strip sample in a straight state, and recording the tension value in the straight state;

[0009] The tension is stopped and the shape, displacement and strain data of the ultra-thin strip sample are acquired based on a high-speed camera.

[0010] Optionally, the process of forming original speckles on the surface of the ultra-thin strip sample based on black and white spray paint includes:

[0011] Cleaning the surface oil stains of the ultra-thin strip sample;

[0012] The surface gloss of the extremely thin strip sample is covered by white spray paint, and irregular scattered spots are formed by black spray paint to obtain original speckles.

[0013] Optionally, the wave-shaped defects include simple wave-shaped defects and complex wave-shaped defects; in the process of cleaning the surface oil stains of the ultra-thin strip sample, the wave shape of the sample in a relaxed state is not affected.

[0014] Optionally, in the process of forming irregular scattered spots based on black spray paint, the white background and the spots of the scattered spots each account for 50% to avoid overlapping distribution of the spots.

[0015] Optionally, in the process of calibrating the original speckle based on the calibration plate, the calibration plate covers at least 80% of the entire field of view, and the calibration plate is placed in the clamping position of the ultra-thin strip sample and twisted at a small angle.

[0016] Optionally, the process of acquiring the shape, displacement and strain data of the ultra-thin strip sample based on a high-speed camera includes:

[0017] The high-speed camera records the wave shape evolution process of the ultra-thin strip sample in the process of the tension becoming zero, and obtains photographs; the photographs are no less than 25 groups;

[0018] The experimental records are saved, and based on the photographs, the wave shape evolution process and geometric characteristic parameters of the ultra-thin strip sample with wave defects from a straight state to zero tension are obtained, and the shape, displacement and strain data of the ultra-thin strip sample are obtained.

[0019] Optionally, in the process of recording the wave shape evolution of the ultra-thin strip sample, the photographing rate of the high-speed camera is at least twice the rate of applying tension.

[0020] On the other hand, to achieve the above-mentioned purpose, the present invention provides a non-contact wave shape evolution process testing device for precision ultra-thin strips, including a clamping mechanism, a stretching module, an image capturing unit, a fill light device, and an image processing module;

[0021] The clamping mechanism is used to clamp the extremely thin strip sample with wave-shaped defects to the stretching module;

[0022] The stretching module is used to apply tension to the ultra-thin strip sample;

[0023] The image capture unit is used to record the wave shape evolution process of the ultra-thin strip sample;

[0024] The fill light device is used to perform light compensation during the recording process of wave shape evolution;

[0025] The image processing module is used to obtain the geometric characteristic parameters, shape, displacement and strain data of the ultra-thin strip sample.

[0026] Optionally, the stretching module comprises a universal material testing machine, and the stretching module applies tension through the universal material testing machine;

[0027] The image capturing unit comprises a high-speed camera, and the photographing rate of the high-speed camera is twice the moving rate of the beam of the universal material testing machine.

[0028] The technical effects of the present invention are:

[0029] The present invention obtains the wave shape evolution process and geometric characteristic parameters by sampling and cleaning the surface of an extremely thin strip with wave-shaped defects, producing irregular surface speckles, clamping the strip samples, evaluating and calibrating the surface speckle quality of the samples, testing strain and displacement field data during uniform loading and unloading processes, and facilitating the study of elastic buckling theory. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 It is a structural diagram of a non-contact wave shape evolution process testing device for precision ultra-thin strips in an embodiment of the present invention;

[0032] Figure 2 The present invention is a flowchart of a non-contact wave shape evolution process testing method for a precision ultra-thin strip in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0035] Embodiment 1

[0036] like Figure 1-2As shown, in this embodiment, a non-contact wave shape evolution process testing device and method for a precision ultra-thin strip are provided, including:

[0037] Step 1: Cut a sample from any position on the ultra-thin strip with wave-shaped defects after rolling, and use anhydrous ethanol and acetone to clean the surface oil stains;

[0038] Step 2: First, use white matte spray paint to prime the surface of the extremely thin strip to cover the gloss of the metal strip surface, and then spray black matte spray paint to obtain irregular shaped scattered spots;

[0039] Step 3: Use a special fixture to clamp the ultra-thin strip sample to the universal material testing machine. The rolling direction of the strip is consistent with the tensile direction of the testing machine. After the position is determined, lock the fixture;

[0040] Step 4: Install a high-speed camera and fill light, build a Vic-3D full-field strain test system, ensure that the camera field of view completely covers the sample, open the software module to evaluate the quality of irregular speckles on the strip surface, if the speckle quality meets the requirements, click the Calibration Images option in Snap, and use a calibration plate of appropriate size to calibrate the original speckle. If the speckle is unqualified, repeat the second step to make the speckle;

[0041] Step 5: Apply tension to the strip sample by loading with a universal material testing machine until the surface of the ultra-thin strip sample changes from undulating to straight under a certain moderate tension condition, and then suspend the movement of the crossbeam of the testing machine to maintain the tension so that the ultra-thin strip sample remains straight;

[0042] Step 6: Set the shooting rate and the beam movement rate to match, and click the shooting start button and the beam movement button at the same time to unload the tension of the ultra-thin strip sample and record the strip wave shape evolution process until the test machine force value displays zero, stop shooting, and stop the test machine beam movement;

[0043] Step 7: Save the experimental records and post-process the photos taken to obtain the wave shape evolution process and geometric characteristic parameters of the ultra-thin strip sample with wave defects from a straight state to a state after complete tension unloading, and obtain the shape, displacement and strain data of the strip sample in the full field of view in three-dimensional space.

[0044] In some embodiments, the wave defects of the ultra-thin strip include simple wave shapes such as middle waves and side waves and compound wave shapes such as quarter waves and oblique cross waves; the surface cleaning process should be gentle so as not to affect the wave shape in the relaxed state. During the test and stretching of the strip sample, the tension must be kept in the elastic range so as not to destroy the residual stress field of the strip.

[0045] In some embodiments, the white background and black spots of the speckle each account for about 50%, and the black spray paint is held to evenly distribute the paint spots on the surface of the white primer to avoid overlapping distribution of the paint spots, and the paint bottle is slightly shaken to increase the irregularity of the black spots, so as to facilitate the image processing software to recognize the features of the speckle image. The production of speckle can also be hand-painted with a marker pen instead of spraying paint.

[0046] In some embodiments, when the ultra-thin strip sample is clamped into the universal material testing machine, attention should be paid to adjusting the relative position of the sample and the upper and lower clamps so that the length direction of the sample (strip rolling direction) is consistent with the tensile direction, that is, consistent with the force direction, and perpendicular to the width direction.

[0047] In some embodiments, the high-speed camera has an angle of about 15° to 60°, and the crosshairs are used to center the sample, and the sample is filled as much as possible within the entire field of view (retaining the deformation margin of the sample), and the fill light range is also the same; turn on the speckle quality assessment function, focus and adjust the lighting and exposure time, so that the color of the assessment cloud map is purple as a whole, and try 3 to 4 times to ensure that the result is credible; when selecting the calibration plate, pay attention to the size filling about 80% of the entire field of view. During calibration, hold the calibration plate in the sample clamping position and twist it slightly at different angles to allow the test system to recognize the calibration plate, take no less than 25 groups of photos to ensure that the result is credible, analyze the calibration results, and consider the calibration successful if the score is below 0.03, and the red result part can be deleted.

[0048] In some embodiments, a relatively small moving speed is set for the universal material testing machine to stretch the sample. When the surface of the extremely thin strip sample changes from undulating to straight, the crossbeam is stopped and maintained, and the tension value at this time is recorded to facilitate the calculation of the strip wave shape evolution in the data processing process.

[0049] In some embodiments, the matching of the photographing rate and the beam movement rate means that the former is twice the latter, that is, two photos can be taken for each movement step, and the beam movement button is clicked and photos are taken at the same time to record the wave shape evolution process of the strip.

[0050] In some embodiments, all the photographs taken are imported into the Vic-3D system for data processing, and a full-field strain cloud diagram of the wave shape changing with time during the wave shape evolution of the strip sample can be obtained.

[0051] The non-contact wave shape evolution process testing device for precision ultra-thin strips in this embodiment includes a clamping mechanism, a stretching module, an image capture unit, a fill light device, and an image processing module;

[0052] Among them, the clamping mechanism is used to clamp the ultra-thin strip sample with wave-shaped defects to the stretching module; the stretching module is used to apply tension to the ultra-thin strip sample; the image capture unit is used to record the wave shape evolution process of the ultra-thin strip sample; the fill light device is used to perform light compensation during the recording process of the wave shape evolution; the image processing module is used to obtain the geometric characteristic parameters, shape, displacement and strain data of the ultra-thin strip sample.

[0053] In some embodiments, the stretching module includes a universal material testing machine, through which tension is applied; the image capturing unit includes a high-speed camera, and a photographing rate of the high-speed camera is twice a movement rate of the beam of the universal material testing machine.

[0054] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A non-contact wave shape evolution process testing method for precision ultra-thin strips, characterized in that: The following steps are involved: Obtaining an ultra-thin strip sample with a wave-shaped defect, and forming an original speckle on the surface of the ultra-thin strip sample based on black and white spray paint; evaluating the original speckle pattern, and if the quality of the original speckle pattern meets the requirement, calibrating the original speckle pattern based on a calibration plate; Continuously applying tension to the ultra-thin strip sample, and when the surface of the ultra-thin strip sample changes from undulating to straight, maintaining the tension to keep the ultra-thin strip sample in a straight state, and recording the tension value in the straight state; Stop maintaining the tension, and obtain shape, displacement and strain data of the ultra-thin strip sample based on a high-speed camera; The process of forming the original speckle on the surface of the ultra-thin strip sample based on black and white spray paint includes: Cleaning the surface oil stains of the ultra-thin strip sample; The surface gloss of the ultra-thin strip sample is covered by white spray paint, and irregular scattered spots are formed by black spray paint to obtain original speckles; The wave-shaped defects include simple wave-shaped defects and complex wave-shaped defects; in the process of cleaning the surface oil stains of the ultra-thin strip sample, the wave shape of the sample in a relaxed state is not affected; In the process of calibrating the original speckle based on the calibration plate, the calibration plate covers at least 80% of the entire field of view, and the calibration plate is placed in the clamping position of the ultra-thin strip sample and twisted at a small angle; The process of obtaining the shape, displacement and strain data of the ultra-thin strip sample based on a high-speed camera includes: The high-speed camera records the wave shape evolution process of the ultra-thin strip sample in the process of the tension becoming zero, and obtains photographs; the photographs are no less than 25 groups; The experimental records are saved, and based on the photographs, the wave shape evolution process and geometric characteristic parameters of the ultra-thin strip sample with wave defects from a straight state to zero tension are obtained, and the shape, displacement and strain data of the ultra-thin strip sample are obtained.

2. The non-contact wave shape evolution process testing method for precision ultra-thin strip according to claim 1 is characterized in that: In the process of forming irregular scattered spots based on black spray paint, the white background and spots of the scattered spots each account for 50%, avoiding overlapping distribution of spots.

3. The non-contact wave shape evolution process testing method for precision ultra-thin strip according to claim 1 is characterized in that: In the process of recording the wave shape evolution of the ultra-thin strip sample, the photographing rate of the high-speed camera is at least twice the rate of applying tension.

4. A non-contact wave shape evolution process testing device for precision ultra-thin strips, characterized in that: Used to implement the method described in any one of claims 1 to 3, comprising a clamping mechanism, a stretching module, an image capturing unit, a fill light device, and an image processing module; The clamping mechanism is used to clamp the extremely thin strip sample with wave-shaped defects to the stretching module; The stretching module is used to apply tension to the ultra-thin strip sample; The image capture unit is used to record the wave shape evolution process of the ultra-thin strip sample; The fill light device is used to perform light compensation during the recording process of wave shape evolution; The image processing module is used to obtain the geometric characteristic parameters, shape, displacement and strain data of the ultra-thin strip sample.

5. The non-contact wave shape evolution process testing device for precision ultra-thin strips according to claim 4 is characterized in that: The stretching module includes a universal material testing machine, and the stretching module applies tension through the universal material testing machine; The image capturing unit comprises a high-speed camera, and the photographing rate of the high-speed camera is twice the moving rate of the beam of the universal material testing machine.

Images