Crimping forming and strain testing device for small-caliber thin plate and using method of curling forming and strain testing device

Abstract

The invention provides a small-caliber thin plate curling forming and strain testing device and a using method thereof.The small-caliber thin plate curling forming and strain testing device comprises a base, the base comprises an upper mounting part and a lower supporting part, two through holes are formed in the front-back direction of the mounting part, and the two through holes of the mounting part are connected with a first lower roller and a second lower roller correspondingly; a sliding groove is formed in the center line of the mounting part, the lower end of the sliding groove is higher than the upper ends of the two through holes of the mounting part, the sliding groove sequentially comprises a front groove, a middle groove and a rear groove from front to back, the sliding groove is slidably connected with the sliding block, and a gear structure is arranged at the rear end of the upper roller. The gear structure is meshed with a tooth-shaped structure arranged on a rack on the side face of the gear structure, the rack is arranged in a clamping groove, and the clamping groove is formed above the two through holes of the installation part. By adjusting the downward pressing amount of the upper roller, curling forming of different diameters is achieved, and the device is suitable for thin plates and ring parts with the wall thickness smaller than 4 mm and the curling diameter smaller than 100 mm.

Description

Technical Field

[0001] The present invention relates to the technical field of material forming and testing, and in particular to a small-caliber thin plate curling forming and strain testing device and a use method thereof. Background Art

[0002] In the field of material forming and performance testing, curling is one of the important means to study the bending properties, plastic deformation capacity and mechanical behavior of materials. Especially in the aerospace, automotive, construction and other industries, the bending forming ability of materials is crucial to the manufacturing quality and performance of products. For curling experiments on small-diameter thin plate materials, how to accurately measure the strain distribution of materials during the forming process is a key issue in material forming research. At present, there is an increasing demand for experiments on plates with thin walls and curling diameters less than 100 mm. This small-scale curling experiment helps to gain a deeper understanding of the mechanical properties of materials under extreme conditions and provide data support for the engineering application of materials.

[0003] At present, common plate rolling devices are mostly used for the rolling and forming of large-diameter and thick plate materials. Although the existing multi-roller plate rolling machine and the three-roller plate rolling machine with pre-bending function (such as application number CN202310471868) can realize the precise rolling of large-sized plates, their structural and functional designs have limitations when conducting small-diameter rolling experiments on thin plates, and cannot meet the precise control requirements of small-diameter plate rolling. On the other hand, although the plate bending performance testing device (such as application number CN201620734266) has the ability of adjustable span and precise measurement, it still faces the problems of complex operation, inconvenient adjustment, and large equipment size in the actual rolling and forming process, and is not suitable for small-scale test environments. In addition, the existing large-diameter plate rolling device (such as application number CN202410270069) is mainly used for the forming and testing of thick-walled cylindrical materials, and cannot be effectively applied to the rolling experiments of small-diameter thin plates.

[0004] In summary, the existing technology still has significant deficiencies in the precise rolling and strain testing of thin plate materials with a wall thickness of less than 4mm and a curling diameter of less than 100mm. Existing devices are mostly designed for large-sized plates and cannot meet the special needs of small-diameter curling experiments on thin plate materials. Summary of the invention

[0005] According to the above technical problem that the existing plate rolling device cannot be applied to small-diameter thin plates, a small-diameter thin plate rolling forming and strain testing device and its use method are provided. The present invention mainly utilizes the test plate rolling device, combines with a universal testing machine, simplifies the structure of the experimental equipment, and introduces DIC strain testing technology, which provides higher accuracy and convenience for the thin plate rolling forming experiment, filling the gap in the existing technology.

[0006] The technical means adopted by the present invention are as follows:

[0007] The cam is provided with a plurality of through holes, each of which is connected to a first lower roller and a second lower roller respectively; a slide groove is provided at the center line of the mounting portion, the lower end of the slide groove is higher than the upper end of the two through holes of the mounting portion, the slide groove is slidably connected to the slider; a gear structure is provided at the rear end of the upper roller, the gear structure is meshed with a toothed structure on a rack arranged on a side surface of the gear structure, the rack is arranged in a card slot, and the card slot is arranged above the two through holes of the mounting portion; a mounting block is connected to the vertical center line of the back side of the mounting portion, the mounting block is provided with a light hole in the vertical direction, an adjusting screw is installed in the threaded through hole of the adjusting screw connecting column and the light hole of the mounting block, and a DIC testing system is provided on the front side of the mounting portion between the first lower roller and the second lower roller.

[0008] Furthermore, the wall thickness of the small-diameter thin plate is less than 4 mm, and the curling diameter of the small-diameter thin plate is less than 100 mm; from a top view, the size of the small-diameter thin plate curling forming and strain testing device is less than or equal to the size of the lower wedge seat of the universal testing machine.

[0009] Furthermore, the lower end of the support portion is a wedge-shaped structure that matches the shape of the lower wedge-shaped seat of the universal testing machine.

[0010] Furthermore, the slide groove includes a front groove, a middle groove and a rear groove from front to back, and the slider includes an upper roller connecting column, a sliding block and an adjusting screw connecting column from front to back. The front end of the upper roller connecting column is connected to the upper roller, and the rear part of the adjusting screw connecting column is provided with a threaded through hole in the vertical direction; when the slider slides up and down in the slide groove, the rear part of the upper roller connecting column slides up and down in the front groove, the sliding block slides up and down in the middle groove, and the front part of the adjusting screw connecting column slides up and down in the rear groove.

[0011] Furthermore, the two through holes of the mounting portion are horizontally symmetrical with respect to a front vertical center line of the mounting portion.

[0012] Furthermore, the adjusting screw is provided with a scale.

[0013] Furthermore, the DIC testing system includes two high-resolution cameras.

[0014] The present invention also provides a method for using a small-diameter thin plate curling forming and strain testing device, which is implemented based on any one of the above-mentioned small-diameter thin plate curling forming and strain testing devices, and includes the following steps:

[0015] Install the support part of the base on the lower wedge seat of the universal testing machine to make the small-diameter sheet curling and strain testing device horizontal and stable; make the first lower roller and the second lower roller installed normally; connect the DIC test system;

[0016] Select a plate to be tested, the thickness of which is less than 4 mm; perform speckle spraying on the side of the plate to be tested that needs to be tested by DIC, place the plate to be tested on the first lower roller and the second lower roller, with the side of the plate to be tested sprayed with speckles facing the DIC camera, so that the plate to be tested is evenly contacted on the two rollers;

[0017] According to the target downward pressure amount, the rotation scale of the screw is adjusted to adjust the upper roller to press down;

[0018] Connect the upper chuck of the tensile testing machine to the upper part of the rack, start the tensile testing machine, and the rack drives the upper roller to rotate by moving up and down, so that the plate to be tested is curled under the action of the upper roller and the first lower roller and the second lower roller;

[0019] Under the pressure and rotation of the upper roller, the sheet gradually curls, and through the friction and the cooperation between the rollers, the sheet is rolled into shape;

[0020] After curling is completed, the DIC test system is used to monitor and record the forming status of the curled sheet in real time and collect relevant data during the curling process.

[0021] Furthermore, the speckle spraying is performed using matte white primer and matte black spray paint.

[0022] Furthermore, the target pressing amount of the upper roller is calculated as follows:

[0023]

[0024] Where: h is the target reduction, R is the target curling radius, r is the radius of the lower roller, o1o2 is the center distance of the lower roller, and t is the plate thickness.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The present invention provides a small-diameter thin plate curling and strain testing device and method, which can achieve curling of different diameters by adjusting the downward pressure of the upper roller, and is suitable for thin plates and ring parts with a wall thickness of less than 4mm and a curling diameter of less than 100mm. The device consists of a base, upper and lower rollers, a slider, an adjusting screw and a rack, etc., and is powered by a tensile testing machine to achieve pre-bending and rolling of the plate between the rollers. The device has the characteristics of simple operation, adjustable precision, and efficient testing, and is suitable for colleges and universities and research institutions to conduct relevant material performance tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 It is the front view of the present invention.

[0029] Figure 2 It is a side view of the present invention.

[0030] Figure 3 It is a stereogram of the present invention.

[0031] Figure 4 It is an exploded view of the present invention.

[0032] Figure 5 This is a slider diagram of the present invention.

[0033] Figure 6 This is the position diagram when the downward pressure of the roller of the present invention is zero.

[0034] Figure 7 This is the position diagram when the downward pressure of the roller of the present invention is h.

[0035] Figure 8 This is a schematic cross-sectional view of the Q235+TA1 titanium steel composite plate in Example 2 of the present invention.

[0036] In the figure: 1. base; 2. first lower roller; 3. second lower roller; 4. plate to be tested; 5. upper roller; 6. rack; 7. slider; 8. adjusting screw; 9. DIC test system; 10. mounting part; 11. supporting part; 12. slide groove; 13. card groove; 14. mounting block; 15. upper roller connecting column; 16. sliding block; 17. adjusting screw connecting column. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0041] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0042] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0043] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0044] like Figure 1-5 As shown, the present invention provides a small-diameter thin plate curling forming and strain testing device, wherein the wall thickness of the small-diameter thin plate is less than 4 mm, and the curling diameter of the small-diameter thin plate is less than 100 mm. The device comprises a base 1, wherein the base 1 comprises an upper mounting portion 10 and a lower support portion 11, wherein the lower end of the support portion 11 is a wedge-shaped structure adapted to the shape of the lower wedge-shaped seat of the universal testing machine. The mounting portion 10 has two through holes in the front and rear directions, and the two through holes of the mounting portion 10 are horizontally symmetrical with respect to the vertical center line of the front face of the mounting portion 10. The two through holes of the mounting part 10 are connected to the first lower roller 2 and the second lower roller 3 respectively. A slide groove 12 is provided at the center line of the mounting part 10. The lower end of the slide groove 12 is higher than the upper end of the two through holes of the mounting part 10. The slide groove 12 is slidably connected with the slider 7. A gear structure is provided at the rear end of the upper roller 5. The gear structure is meshed with the toothed structure on the rack 6 provided on the side of the gear structure. The rack 6 is provided in the slot 13. The slot 13 is provided above the two through holes of the mounting part 10. A mounting block 14 is connected to the vertical center line of the back of the mounting part 10. The upper part of the mounting block 14 is lower than the lower part of the slide groove 12. The mounting block 14 is provided with a light hole in the vertical direction. The adjusting screw 8 is installed in the threaded through hole of the adjusting screw connecting column 17 and the light hole of the mounting block 14. The adjusting screw 8 is provided with a scale. A DIC test system 9 is provided on the front of the mounting part 10 between the first lower roller 2 and the second lower roller 3.

[0045] The slide groove 12 includes a front groove, a middle groove and a rear groove from front to back, and the slider 7 includes an upper roller connecting column 15, a sliding block 16 and an adjusting screw connecting column 17 from front to back. The front end of the upper roller connecting column 15 is connected to the upper roller 5, and the rear part of the adjusting screw connecting column 17 is provided with a threaded through hole in the vertical direction; when the slider 7 slides up and down in the slide groove 12, the rear part of the upper roller connecting column 15 slides up and down in the front groove, the sliding block 16 slides up and down in the middle groove, and the front part of the adjusting screw connecting column 17 slides up and down in the rear groove.

[0046] Base 1: The base 1 is used to support the structure of the entire device to ensure stable operation of each component. The base 1 is fixedly connected to the first lower roller 2 and the second lower roller 3 to provide a stable plate rolling working platform. The lower end of the base 1 is a wedge-shaped structure that can be installed in conjunction with a universal testing machine; the upper end is the main structure, which is provided with mounting holes, mounting slots, etc. The back of the base 1 is provided with a mounting hole for the adjusting screw 8, which is a light hole; the upper end of the base is provided with a slide groove for installing the slider 7.

[0047] The first lower roller 2 and the second lower roller 3: The lower rollers are used to support the plate to be tested. The two lower rollers are fixedly installed in holes to ensure rigidity and have no power themselves.

[0048] Upper roller 5: The upper roller 5 is located above the plate 4 to be tested and is responsible for applying pressure and providing rotational power. The plate 4 to be tested is pre-bent between the two lower rollers and curled by the friction between the plate 4 to be tested and the three rollers. The upper roller 5 is mounted on the slider 7 and the downward pressure operation is achieved by the up and down movement of the slider 7. By adjusting the downward pressure of the upper roller 5, ring parts of different diameters (or different curling radii) can be rolled. A gear structure is provided on one side of the upper roller 5, which cooperates with the rack 6 during operation, and the rotation of the upper roller 5 is achieved by the linkage of the gear and rack.

[0049] Rack 6: The rack 6 is mainly used to convert power. The upper end is connected to the upper chuck of the tensile testing machine, and the lower end cooperates with the upper roller 5 to convert linear motion into rotational motion. The rack 6 is installed in the slot of the base 1 to ensure stable operation during its operation.

[0050] Slider 7: The slider 7 is used to drive the upper roller to move up and down in the vertical direction to ensure that the applied pressure is uniform and adjustable. The slider 7 is connected to the upper roller 5 and is controlled by the adjusting screw 8. The slider 7 is provided with a threaded hole, which cooperates with the adjusting screw 8 to achieve precise adjustment of the position of the upper roller.

[0051] Adjusting screw 8: The adjusting screw 8 is provided with a scale, and the downward pressing distance of the upper roller 5 can be accurately adjusted by rotating it to meet the curling requirements of thin plates of different specifications. The lower end of the adjusting screw 8 is fixedly installed in the circular hole B on the back of the base. The circular hole is a smooth hole, and this part of the screw is a smooth rod design (no thread) to ensure that it can move smoothly when rotating.

[0052] DIC test system 9: The DIC (digital image processing technology) test system is used to monitor and record the strain distribution on the surface of the sheet in real time during the curling process, and accurately measure the surface of the sheet through non-contact digital image correlation technology to obtain high-resolution strain data. The DIC test system is equipped with two high-resolution cameras that can collect image information at each curling deformation stage of the sheet.

[0053] The present invention also provides a working method of a small-caliber thin plate curling forming and strain testing device, comprising the following steps:

[0054] 1. Equipment installation and debugging: Install the base 1 on the lower wedge seat of the universal testing machine to ensure that the equipment is horizontal and stable. Check the installation status of the first lower roller 2 and the second lower roller 3 to ensure that they are in normal condition. Connect the DIC test system 9 and debug to ensure that all components work normally.

[0055] 2. Plate preparation: Select the plate 4 to be tested, which is required to be less than 4mm thick, and meet the test requirements in length and width. Speckle spray the side to be tested by DIC (using matte white primer + matte black spray paint for spraying), and place the plate 4 to be tested on the first lower roller 2 and the second lower roller 3, with the side sprayed with speckle facing the DIC camera, to ensure that the plate 4 to be tested is evenly contacted on the two rollers.

[0056] 3. Adjust the pressing distance of the upper roller 5: By adjusting the screw 8 to rotate the scale, accurately adjust the pressing distance of the upper roller 5, and adjust it according to the expected curling diameter to ensure that the pressure between the upper roller 5 and the sheet 4 to be tested is appropriate. (According to the target curling diameter, the pressing distance is obtained by theoretical calculation)

[0057] Theoretical calculation formula for the amount of pressure reduction:

[0058]

[0059] Where: h is the amount of reduction, R is the target curling radius, r is the radius of the lower roller, o1o2 is the center distance of the lower roller, and t is the plate thickness.

[0060] 4. Start the testing machine: connect the upper chuck of the tensile testing machine to the rack 6, start the testing machine, and the rack 6 drives the upper roller 5 to rotate by moving up and down, driving the plate to curl under the action of the upper roller 5 and the first lower roller 2 and the second lower roller 3.

[0061] 5. Curling process: The sheet 4 gradually curls under the pressure and rotation of the upper roller 5. The sheet is rolled into shape through friction and the cooperation between the rollers.

[0062] 6. Ring trial production: For ring parts with a width less than 50mm, the same steps can be used for rolling operations, adjusting the positions of the upper and lower rollers to ensure that they meet the parts processing requirements.

[0063] 7. Testing and data recording: After curling is completed, the DIC test system is used to monitor and record the forming state of the curled sheet in real time, and collect relevant data during the curling process, including deformation and other conditions.

[0064] 8. Equipment reset and maintenance: After completing the test, turn off the testing machine, reset the equipment, clean all components, and regularly check the status of the adjusting screw, rack and rollers to ensure normal use in the next test.

[0065] Example 1

[0066] The DC04 steel plate was rolled using the present invention and the curling deformation was tested:

[0067] Materials: DC04 deep-drawn cold-rolled steel plate with a thickness of 1.5mm is used. The steel plate is cut into 40mm wide and 251.2mm long, which is used to curl ring parts with an outer diameter of 80mm; one side of the plate is sprayed with speckle, first with white matte primer, and then with black matte spray paint.

[0068] Implementation steps:

[0069] (1) Equipment installation and commissioning: Fix the base 1 of the device on the platform of the universal testing machine to ensure that the base is horizontal and stable. Install the upper roller 5 and the first lower roller 2 and the second lower roller 3. The slider 7 is connected to the upper roller 5 and installed in the guide groove above the base 1. The adjusting screw 8 is installed in the light hole on the back of the base. The plate 4 to be tested is placed between the upper roller and the lower roller, and the adjusting screw 8 is rotated to adjust the initial position of the upper roller 5, that is, to the zero position state (such as Figure 6 shown).

[0070] (2) DIC preparation: Aim the two cameras of the DIC system at the side of the sample sprayed with speckles, and set the system-related triggering and recording parameters.

[0071] (3) Device parameter setting: Adjust the downward pressure distance h of the upper roller 5, such as Figure 7As shown in the figure, according to formula (1), the adjustment screw 8 is used to accurately adjust the downward pressure distance to 25.2 mm, which can ensure that the upper roller 5 can provide appropriate pressure for curling and obtain the product with the target curling diameter at the same time. Check the coordination between the rack 6 and the upper roller 5 to ensure smooth rotation between the rack 6 and the gear of the upper roller 5. Set the parameters of the testing machine, set the downward pressure speed and maximum compression force of the tensile testing machine, and ensure the stability of the equipment during the rolling process.

[0072] (4) Curling operation: As the upper chuck of the testing machine drives the rack 6 to move, the sheet 4 to be tested is gradually rolled into a ring with a diameter of 80 mm under the interaction of the upper and lower rollers. Preferably, the rack 6 moves linearly upward or downward, which can enable the upper roller 5 to achieve forward or reverse rotation, and can meet the requirements of multiple curling of the sheet 4 to be tested.

[0073] (5) Curling forming test: The entire curling process of the sheet 4 to be tested is recorded by a DIC (digital image correlation) test system installed on the device, and the curling deformation strain distribution and deformation behavior are analyzed by the test system.

[0074] (6) Finished product inspection: After rolling, the annular parts are taken out and the outer diameter and roundness of the parts are measured using calipers and other inspection equipment to ensure that they meet the set outer diameter requirement of 80 mm, and their surface quality and curling uniformity are inspected.

[0075] Example 2

[0076] The titanium steel composite plate was rolled by the present invention and the composite interface deformation behavior was tested:

[0077] Materials: Q235+TA1 titanium steel composite plate is selected, with a plate thickness of 4mm, of which the base material Q235 is 3mm thick and the composite material TA2 is 1mm thick. The composite plate is cut into 30mm wide and 314mm long, and is used to curl ring parts with an outer diameter of 100mm. At the same time, the deformation of its composite interface during the curling process is tested; on the plate section (such as Figure 8 As shown, for scattered spots spraying, first use white matte primer to prime, and then use black matte spray paint to spray the scattered spots.

[0078] Implementation steps: Same as those described in Example 1. The downward pressing distance of the upper roller 5 can be obtained by the formula (1), h is 17.4 mm. DIC collects images of the interface during the curling process, and through post-processing analysis, the interface deformation behavior is obtained, including the thickness change of the composite material and the substrate and the deformation of the composite interface.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A small-caliber sheet metal curling and strain testing device, characterized in that: The invention comprises a base (1), wherein the base (1) comprises an upper mounting portion (10) and a lower supporting portion (11), wherein two through holes are provided in the front-rear direction of the mounting portion (10), wherein the two through holes of the mounting portion (10) are respectively connected to a first lower roller (2) and a second lower roller (3), wherein a slide groove (12) is provided at the center line of the mounting portion (10), wherein the lower end of the slide groove (12) is higher than the upper end of the two through holes of the mounting portion (10), wherein the slide groove (12) is slidably connected to a slider (7), and a gear structure is provided at the rear end of the upper roller (5), wherein the gear structure is connected to a rack (6) provided on the side of the gear structure. The toothed structures are meshed with each other, the rack (6) is arranged in a slot (13), the slot (13) is arranged above the two through holes of the mounting portion (10), a mounting block (14) is connected to the vertical center line of the back side of the mounting portion (10), the upper part of the mounting block (14) is lower than the lower part of the slide groove (12), the mounting block (14) is provided with a light hole in the vertical direction, the adjusting screw (8) is installed in the threaded through hole of the adjusting screw connecting column (17) and the light hole of the mounting block (14), and a DIC test system (9) is arranged on the front side of the mounting portion (10) between the first lower roller (2) and the second lower roller (3).

2. The small-diameter sheet metal curling and strain testing device according to claim 1, characterized in that: The wall thickness of the small-diameter thin plate is less than 4 mm, and the curling diameter of the small-diameter thin plate is less than 100 mm; from a top view, the size of the small-diameter thin plate curling forming and strain testing device is less than or equal to the size of the lower wedge seat of the universal testing machine.

3. The small-caliber sheet metal curling and strain testing device according to claim 1, characterized in that: The lower end of the support portion (11) is a wedge-shaped structure that matches the shape of the lower wedge-shaped seat of the universal testing machine.

4. The small-caliber sheet metal curling and strain testing device according to claim 1, characterized in that: The slide groove (12) includes a front groove, a middle groove and a rear groove from front to back, and the slider (7) includes an upper roller connecting column (15), a sliding block (16) and an adjusting screw connecting column (17) from front to back. The front end of the upper roller connecting column (15) is connected to the upper roller (5), and the rear part of the adjusting screw connecting column (17) is provided with a threaded through hole in the vertical direction; when the slider (7) slides up and down in the slide groove (12), the rear part of the upper roller connecting column (15) slides up and down in the front groove, the sliding block (16) slides up and down in the middle groove, and the front part of the adjusting screw connecting column (17) slides up and down in the rear groove.

5. The small-caliber sheet metal curling and strain testing device according to claim 1, characterized in that: The two through holes of the mounting portion (10) are horizontally symmetrical with respect to a vertical center line of the front side of the mounting portion (10).

6. The small-caliber sheet metal curling and strain testing device according to claim 1, characterized in that: The adjusting screw (8) is provided with a scale.

7. The small-diameter sheet metal curling and strain testing device according to claim 1, characterized in that: The DIC testing system (9) includes two high-resolution cameras.

8. A method for using a small-diameter sheet metal curling and strain testing device, based on the small-diameter sheet metal curling and strain testing device according to any one of claims 1 to 7, characterized in that: The steps include: The support part (11) of the base (1) is installed on the lower wedge seat of the universal testing machine, so that the small-diameter thin plate curling forming and strain testing device is horizontal and stable; the first lower roller (2) and the second lower roller (3) are installed in a normal state; Connecting to the DIC test system (9); Selecting a plate (4) to be tested, wherein the thickness of the plate (4) to be tested is less than 4 mm; performing speckle spraying on the side of the plate (4) to be tested that needs to be tested by DIC, placing the plate (4) to be tested on a first lower roller (2) and a second lower roller (3), with the side to be tested on which the speckle spraying is to be tested facing the DIC camera, so that the plate (4) to be tested is evenly contacted on the two rollers; The upper roller (5) is adjusted to press downward by adjusting the rotation scale of the screw rod (8) according to the target downward pressure amount; The upper chuck of the tensile testing machine is connected to the upper part of the rack (6), and the tensile testing machine is started. The rack (6) drives the upper roller (5) to rotate by moving up and down, and drives the plate (4) to be tested to curl under the action of the upper roller (5) and the first lower roller (2) and the second lower roller (3); Under the pressure and rotation of the upper roller (5), the sheet gradually curls, and the sheet is rolled into shape through friction and the cooperation between the rollers. After curling is completed, the DIC test system (9) is used to monitor and record the forming state of the curled sheet in real time and collect relevant data during the curling process.

9. The small-diameter sheet curling and strain testing method according to claim 7, characterized in that: The speckle spray is applied using matte white primer and matte black spray paint.

10. The small-diameter sheet curling and strain testing method according to claim 7, characterized in that: The target pressing amount of the upper roller (5) is calculated as follows: Where: h is the target reduction, R is the target curling radius, r is the radius of the lower roller, o1o2 is the center distance of the lower roller, and t is the plate thickness.

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